1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * kernel/workqueue.c - generic async execution with shared worker pool |
4 | * |
5 | * Copyright (C) 2002 Ingo Molnar |
6 | * |
7 | * Derived from the taskqueue/keventd code by: |
8 | * David Woodhouse <dwmw2@infradead.org> |
9 | * Andrew Morton |
10 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
11 | * Theodore Ts'o <tytso@mit.edu> |
12 | * |
13 | * Made to use alloc_percpu by Christoph Lameter. |
14 | * |
15 | * Copyright (C) 2010 SUSE Linux Products GmbH |
16 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> |
17 | * |
18 | * This is the generic async execution mechanism. Work items as are |
19 | * executed in process context. The worker pool is shared and |
20 | * automatically managed. There are two worker pools for each CPU (one for |
21 | * normal work items and the other for high priority ones) and some extra |
22 | * pools for workqueues which are not bound to any specific CPU - the |
23 | * number of these backing pools is dynamic. |
24 | * |
25 | * Please read Documentation/core-api/workqueue.rst for details. |
26 | */ |
27 | |
28 | #include <linux/export.h> |
29 | #include <linux/kernel.h> |
30 | #include <linux/sched.h> |
31 | #include <linux/init.h> |
32 | #include <linux/signal.h> |
33 | #include <linux/completion.h> |
34 | #include <linux/workqueue.h> |
35 | #include <linux/slab.h> |
36 | #include <linux/cpu.h> |
37 | #include <linux/notifier.h> |
38 | #include <linux/kthread.h> |
39 | #include <linux/hardirq.h> |
40 | #include <linux/mempolicy.h> |
41 | #include <linux/freezer.h> |
42 | #include <linux/debug_locks.h> |
43 | #include <linux/lockdep.h> |
44 | #include <linux/idr.h> |
45 | #include <linux/jhash.h> |
46 | #include <linux/hashtable.h> |
47 | #include <linux/rculist.h> |
48 | #include <linux/nodemask.h> |
49 | #include <linux/moduleparam.h> |
50 | #include <linux/uaccess.h> |
51 | #include <linux/sched/isolation.h> |
52 | #include <linux/sched/debug.h> |
53 | #include <linux/nmi.h> |
54 | #include <linux/kvm_para.h> |
55 | #include <linux/delay.h> |
56 | |
57 | #include "workqueue_internal.h" |
58 | |
59 | enum { |
60 | /* |
61 | * worker_pool flags |
62 | * |
63 | * A bound pool is either associated or disassociated with its CPU. |
64 | * While associated (!DISASSOCIATED), all workers are bound to the |
65 | * CPU and none has %WORKER_UNBOUND set and concurrency management |
66 | * is in effect. |
67 | * |
68 | * While DISASSOCIATED, the cpu may be offline and all workers have |
69 | * %WORKER_UNBOUND set and concurrency management disabled, and may |
70 | * be executing on any CPU. The pool behaves as an unbound one. |
71 | * |
72 | * Note that DISASSOCIATED should be flipped only while holding |
73 | * wq_pool_attach_mutex to avoid changing binding state while |
74 | * worker_attach_to_pool() is in progress. |
75 | */ |
76 | POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */ |
77 | POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ |
78 | |
79 | /* worker flags */ |
80 | WORKER_DIE = 1 << 1, /* die die die */ |
81 | WORKER_IDLE = 1 << 2, /* is idle */ |
82 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
83 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
84 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
85 | WORKER_REBOUND = 1 << 8, /* worker was rebound */ |
86 | |
87 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | |
88 | WORKER_UNBOUND | WORKER_REBOUND, |
89 | |
90 | NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ |
91 | |
92 | UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ |
93 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
94 | |
95 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
96 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ |
97 | |
98 | MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, |
99 | /* call for help after 10ms |
100 | (min two ticks) */ |
101 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
102 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ |
103 | |
104 | /* |
105 | * Rescue workers are used only on emergencies and shared by |
106 | * all cpus. Give MIN_NICE. |
107 | */ |
108 | RESCUER_NICE_LEVEL = MIN_NICE, |
109 | HIGHPRI_NICE_LEVEL = MIN_NICE, |
110 | |
111 | WQ_NAME_LEN = 24, |
112 | }; |
113 | |
114 | /* |
115 | * Structure fields follow one of the following exclusion rules. |
116 | * |
117 | * I: Modifiable by initialization/destruction paths and read-only for |
118 | * everyone else. |
119 | * |
120 | * P: Preemption protected. Disabling preemption is enough and should |
121 | * only be modified and accessed from the local cpu. |
122 | * |
123 | * L: pool->lock protected. Access with pool->lock held. |
124 | * |
125 | * K: Only modified by worker while holding pool->lock. Can be safely read by |
126 | * self, while holding pool->lock or from IRQ context if %current is the |
127 | * kworker. |
128 | * |
129 | * S: Only modified by worker self. |
130 | * |
131 | * A: wq_pool_attach_mutex protected. |
132 | * |
133 | * PL: wq_pool_mutex protected. |
134 | * |
135 | * PR: wq_pool_mutex protected for writes. RCU protected for reads. |
136 | * |
137 | * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads. |
138 | * |
139 | * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or |
140 | * RCU for reads. |
141 | * |
142 | * WQ: wq->mutex protected. |
143 | * |
144 | * WR: wq->mutex protected for writes. RCU protected for reads. |
145 | * |
146 | * MD: wq_mayday_lock protected. |
147 | * |
148 | * WD: Used internally by the watchdog. |
149 | */ |
150 | |
151 | /* struct worker is defined in workqueue_internal.h */ |
152 | |
153 | struct worker_pool { |
154 | raw_spinlock_t lock; /* the pool lock */ |
155 | int cpu; /* I: the associated cpu */ |
156 | int node; /* I: the associated node ID */ |
157 | int id; /* I: pool ID */ |
158 | unsigned int flags; /* L: flags */ |
159 | |
160 | unsigned long watchdog_ts; /* L: watchdog timestamp */ |
161 | bool cpu_stall; /* WD: stalled cpu bound pool */ |
162 | |
163 | /* |
164 | * The counter is incremented in a process context on the associated CPU |
165 | * w/ preemption disabled, and decremented or reset in the same context |
166 | * but w/ pool->lock held. The readers grab pool->lock and are |
167 | * guaranteed to see if the counter reached zero. |
168 | */ |
169 | int nr_running; |
170 | |
171 | struct list_head worklist; /* L: list of pending works */ |
172 | |
173 | int nr_workers; /* L: total number of workers */ |
174 | int nr_idle; /* L: currently idle workers */ |
175 | |
176 | struct list_head idle_list; /* L: list of idle workers */ |
177 | struct timer_list idle_timer; /* L: worker idle timeout */ |
178 | struct work_struct idle_cull_work; /* L: worker idle cleanup */ |
179 | |
180 | struct timer_list mayday_timer; /* L: SOS timer for workers */ |
181 | |
182 | /* a workers is either on busy_hash or idle_list, or the manager */ |
183 | DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); |
184 | /* L: hash of busy workers */ |
185 | |
186 | struct worker *manager; /* L: purely informational */ |
187 | struct list_head workers; /* A: attached workers */ |
188 | struct list_head dying_workers; /* A: workers about to die */ |
189 | struct completion *detach_completion; /* all workers detached */ |
190 | |
191 | struct ida worker_ida; /* worker IDs for task name */ |
192 | |
193 | struct workqueue_attrs *attrs; /* I: worker attributes */ |
194 | struct hlist_node hash_node; /* PL: unbound_pool_hash node */ |
195 | int refcnt; /* PL: refcnt for unbound pools */ |
196 | |
197 | /* |
198 | * Destruction of pool is RCU protected to allow dereferences |
199 | * from get_work_pool(). |
200 | */ |
201 | struct rcu_head rcu; |
202 | }; |
203 | |
204 | /* |
205 | * Per-pool_workqueue statistics. These can be monitored using |
206 | * tools/workqueue/wq_monitor.py. |
207 | */ |
208 | enum pool_workqueue_stats { |
209 | PWQ_STAT_STARTED, /* work items started execution */ |
210 | PWQ_STAT_COMPLETED, /* work items completed execution */ |
211 | PWQ_STAT_CPU_TIME, /* total CPU time consumed */ |
212 | PWQ_STAT_CPU_INTENSIVE, /* wq_cpu_intensive_thresh_us violations */ |
213 | PWQ_STAT_CM_WAKEUP, /* concurrency-management worker wakeups */ |
214 | PWQ_STAT_REPATRIATED, /* unbound workers brought back into scope */ |
215 | PWQ_STAT_MAYDAY, /* maydays to rescuer */ |
216 | PWQ_STAT_RESCUED, /* linked work items executed by rescuer */ |
217 | |
218 | PWQ_NR_STATS, |
219 | }; |
220 | |
221 | /* |
222 | * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS |
223 | * of work_struct->data are used for flags and the remaining high bits |
224 | * point to the pwq; thus, pwqs need to be aligned at two's power of the |
225 | * number of flag bits. |
226 | */ |
227 | struct pool_workqueue { |
228 | struct worker_pool *pool; /* I: the associated pool */ |
229 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
230 | int work_color; /* L: current color */ |
231 | int flush_color; /* L: flushing color */ |
232 | int refcnt; /* L: reference count */ |
233 | int nr_in_flight[WORK_NR_COLORS]; |
234 | /* L: nr of in_flight works */ |
235 | |
236 | /* |
237 | * nr_active management and WORK_STRUCT_INACTIVE: |
238 | * |
239 | * When pwq->nr_active >= max_active, new work item is queued to |
240 | * pwq->inactive_works instead of pool->worklist and marked with |
241 | * WORK_STRUCT_INACTIVE. |
242 | * |
243 | * All work items marked with WORK_STRUCT_INACTIVE do not participate |
244 | * in pwq->nr_active and all work items in pwq->inactive_works are |
245 | * marked with WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE |
246 | * work items are in pwq->inactive_works. Some of them are ready to |
247 | * run in pool->worklist or worker->scheduled. Those work itmes are |
248 | * only struct wq_barrier which is used for flush_work() and should |
249 | * not participate in pwq->nr_active. For non-barrier work item, it |
250 | * is marked with WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works. |
251 | */ |
252 | int nr_active; /* L: nr of active works */ |
253 | int max_active; /* L: max active works */ |
254 | struct list_head inactive_works; /* L: inactive works */ |
255 | struct list_head pwqs_node; /* WR: node on wq->pwqs */ |
256 | struct list_head mayday_node; /* MD: node on wq->maydays */ |
257 | |
258 | u64 stats[PWQ_NR_STATS]; |
259 | |
260 | /* |
261 | * Release of unbound pwq is punted to a kthread_worker. See put_pwq() |
262 | * and pwq_release_workfn() for details. pool_workqueue itself is also |
263 | * RCU protected so that the first pwq can be determined without |
264 | * grabbing wq->mutex. |
265 | */ |
266 | struct kthread_work release_work; |
267 | struct rcu_head rcu; |
268 | } __aligned(1 << WORK_STRUCT_FLAG_BITS); |
269 | |
270 | /* |
271 | * Structure used to wait for workqueue flush. |
272 | */ |
273 | struct wq_flusher { |
274 | struct list_head list; /* WQ: list of flushers */ |
275 | int flush_color; /* WQ: flush color waiting for */ |
276 | struct completion done; /* flush completion */ |
277 | }; |
278 | |
279 | struct wq_device; |
280 | |
281 | /* |
282 | * The externally visible workqueue. It relays the issued work items to |
283 | * the appropriate worker_pool through its pool_workqueues. |
284 | */ |
285 | struct workqueue_struct { |
286 | struct list_head pwqs; /* WR: all pwqs of this wq */ |
287 | struct list_head list; /* PR: list of all workqueues */ |
288 | |
289 | struct mutex mutex; /* protects this wq */ |
290 | int work_color; /* WQ: current work color */ |
291 | int flush_color; /* WQ: current flush color */ |
292 | atomic_t nr_pwqs_to_flush; /* flush in progress */ |
293 | struct wq_flusher *first_flusher; /* WQ: first flusher */ |
294 | struct list_head flusher_queue; /* WQ: flush waiters */ |
295 | struct list_head flusher_overflow; /* WQ: flush overflow list */ |
296 | |
297 | struct list_head maydays; /* MD: pwqs requesting rescue */ |
298 | struct worker *rescuer; /* MD: rescue worker */ |
299 | |
300 | int nr_drainers; /* WQ: drain in progress */ |
301 | int saved_max_active; /* WQ: saved pwq max_active */ |
302 | |
303 | struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ |
304 | struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */ |
305 | |
306 | #ifdef CONFIG_SYSFS |
307 | struct wq_device *wq_dev; /* I: for sysfs interface */ |
308 | #endif |
309 | #ifdef CONFIG_LOCKDEP |
310 | char *lock_name; |
311 | struct lock_class_key key; |
312 | struct lockdep_map lockdep_map; |
313 | #endif |
314 | char name[WQ_NAME_LEN]; /* I: workqueue name */ |
315 | |
316 | /* |
317 | * Destruction of workqueue_struct is RCU protected to allow walking |
318 | * the workqueues list without grabbing wq_pool_mutex. |
319 | * This is used to dump all workqueues from sysrq. |
320 | */ |
321 | struct rcu_head rcu; |
322 | |
323 | /* hot fields used during command issue, aligned to cacheline */ |
324 | unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ |
325 | struct pool_workqueue __percpu __rcu **cpu_pwq; /* I: per-cpu pwqs */ |
326 | }; |
327 | |
328 | static struct kmem_cache *pwq_cache; |
329 | |
330 | /* |
331 | * Each pod type describes how CPUs should be grouped for unbound workqueues. |
332 | * See the comment above workqueue_attrs->affn_scope. |
333 | */ |
334 | struct wq_pod_type { |
335 | int nr_pods; /* number of pods */ |
336 | cpumask_var_t *pod_cpus; /* pod -> cpus */ |
337 | int *pod_node; /* pod -> node */ |
338 | int *cpu_pod; /* cpu -> pod */ |
339 | }; |
340 | |
341 | static struct wq_pod_type wq_pod_types[WQ_AFFN_NR_TYPES]; |
342 | static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_CACHE; |
343 | |
344 | static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = { |
345 | [WQ_AFFN_DFL] = "default" , |
346 | [WQ_AFFN_CPU] = "cpu" , |
347 | [WQ_AFFN_SMT] = "smt" , |
348 | [WQ_AFFN_CACHE] = "cache" , |
349 | [WQ_AFFN_NUMA] = "numa" , |
350 | [WQ_AFFN_SYSTEM] = "system" , |
351 | }; |
352 | |
353 | /* |
354 | * Per-cpu work items which run for longer than the following threshold are |
355 | * automatically considered CPU intensive and excluded from concurrency |
356 | * management to prevent them from noticeably delaying other per-cpu work items. |
357 | * ULONG_MAX indicates that the user hasn't overridden it with a boot parameter. |
358 | * The actual value is initialized in wq_cpu_intensive_thresh_init(). |
359 | */ |
360 | static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX; |
361 | module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644); |
362 | |
363 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ |
364 | static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); |
365 | module_param_named(power_efficient, wq_power_efficient, bool, 0444); |
366 | |
367 | static bool wq_online; /* can kworkers be created yet? */ |
368 | |
369 | /* buf for wq_update_unbound_pod_attrs(), protected by CPU hotplug exclusion */ |
370 | static struct workqueue_attrs *wq_update_pod_attrs_buf; |
371 | |
372 | static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ |
373 | static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ |
374 | static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ |
375 | /* wait for manager to go away */ |
376 | static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait); |
377 | |
378 | static LIST_HEAD(workqueues); /* PR: list of all workqueues */ |
379 | static bool workqueue_freezing; /* PL: have wqs started freezing? */ |
380 | |
381 | /* PL&A: allowable cpus for unbound wqs and work items */ |
382 | static cpumask_var_t wq_unbound_cpumask; |
383 | |
384 | /* for further constrain wq_unbound_cpumask by cmdline parameter*/ |
385 | static struct cpumask wq_cmdline_cpumask __initdata; |
386 | |
387 | /* CPU where unbound work was last round robin scheduled from this CPU */ |
388 | static DEFINE_PER_CPU(int, wq_rr_cpu_last); |
389 | |
390 | /* |
391 | * Local execution of unbound work items is no longer guaranteed. The |
392 | * following always forces round-robin CPU selection on unbound work items |
393 | * to uncover usages which depend on it. |
394 | */ |
395 | #ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU |
396 | static bool wq_debug_force_rr_cpu = true; |
397 | #else |
398 | static bool wq_debug_force_rr_cpu = false; |
399 | #endif |
400 | module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644); |
401 | |
402 | /* the per-cpu worker pools */ |
403 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools); |
404 | |
405 | static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ |
406 | |
407 | /* PL: hash of all unbound pools keyed by pool->attrs */ |
408 | static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); |
409 | |
410 | /* I: attributes used when instantiating standard unbound pools on demand */ |
411 | static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; |
412 | |
413 | /* I: attributes used when instantiating ordered pools on demand */ |
414 | static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; |
415 | |
416 | /* |
417 | * I: kthread_worker to release pwq's. pwq release needs to be bounced to a |
418 | * process context while holding a pool lock. Bounce to a dedicated kthread |
419 | * worker to avoid A-A deadlocks. |
420 | */ |
421 | static struct kthread_worker *pwq_release_worker __ro_after_init; |
422 | |
423 | struct workqueue_struct *system_wq __ro_after_init; |
424 | EXPORT_SYMBOL(system_wq); |
425 | struct workqueue_struct *system_highpri_wq __ro_after_init; |
426 | EXPORT_SYMBOL_GPL(system_highpri_wq); |
427 | struct workqueue_struct *system_long_wq __ro_after_init; |
428 | EXPORT_SYMBOL_GPL(system_long_wq); |
429 | struct workqueue_struct *system_unbound_wq __ro_after_init; |
430 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
431 | struct workqueue_struct *system_freezable_wq __ro_after_init; |
432 | EXPORT_SYMBOL_GPL(system_freezable_wq); |
433 | struct workqueue_struct *system_power_efficient_wq __ro_after_init; |
434 | EXPORT_SYMBOL_GPL(system_power_efficient_wq); |
435 | struct workqueue_struct *system_freezable_power_efficient_wq __ro_after_init; |
436 | EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); |
437 | |
438 | static int worker_thread(void *__worker); |
439 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq); |
440 | static void show_pwq(struct pool_workqueue *pwq); |
441 | static void show_one_worker_pool(struct worker_pool *pool); |
442 | |
443 | #define CREATE_TRACE_POINTS |
444 | #include <trace/events/workqueue.h> |
445 | |
446 | #define assert_rcu_or_pool_mutex() \ |
447 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
448 | !lockdep_is_held(&wq_pool_mutex), \ |
449 | "RCU or wq_pool_mutex should be held") |
450 | |
451 | #define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \ |
452 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
453 | !lockdep_is_held(&wq->mutex) && \ |
454 | !lockdep_is_held(&wq_pool_mutex), \ |
455 | "RCU, wq->mutex or wq_pool_mutex should be held") |
456 | |
457 | #define for_each_cpu_worker_pool(pool, cpu) \ |
458 | for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ |
459 | (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ |
460 | (pool)++) |
461 | |
462 | /** |
463 | * for_each_pool - iterate through all worker_pools in the system |
464 | * @pool: iteration cursor |
465 | * @pi: integer used for iteration |
466 | * |
467 | * This must be called either with wq_pool_mutex held or RCU read |
468 | * locked. If the pool needs to be used beyond the locking in effect, the |
469 | * caller is responsible for guaranteeing that the pool stays online. |
470 | * |
471 | * The if/else clause exists only for the lockdep assertion and can be |
472 | * ignored. |
473 | */ |
474 | #define for_each_pool(pool, pi) \ |
475 | idr_for_each_entry(&worker_pool_idr, pool, pi) \ |
476 | if (({ assert_rcu_or_pool_mutex(); false; })) { } \ |
477 | else |
478 | |
479 | /** |
480 | * for_each_pool_worker - iterate through all workers of a worker_pool |
481 | * @worker: iteration cursor |
482 | * @pool: worker_pool to iterate workers of |
483 | * |
484 | * This must be called with wq_pool_attach_mutex. |
485 | * |
486 | * The if/else clause exists only for the lockdep assertion and can be |
487 | * ignored. |
488 | */ |
489 | #define for_each_pool_worker(worker, pool) \ |
490 | list_for_each_entry((worker), &(pool)->workers, node) \ |
491 | if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \ |
492 | else |
493 | |
494 | /** |
495 | * for_each_pwq - iterate through all pool_workqueues of the specified workqueue |
496 | * @pwq: iteration cursor |
497 | * @wq: the target workqueue |
498 | * |
499 | * This must be called either with wq->mutex held or RCU read locked. |
500 | * If the pwq needs to be used beyond the locking in effect, the caller is |
501 | * responsible for guaranteeing that the pwq stays online. |
502 | * |
503 | * The if/else clause exists only for the lockdep assertion and can be |
504 | * ignored. |
505 | */ |
506 | #define for_each_pwq(pwq, wq) \ |
507 | list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \ |
508 | lockdep_is_held(&(wq->mutex))) |
509 | |
510 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
511 | |
512 | static const struct debug_obj_descr work_debug_descr; |
513 | |
514 | static void *work_debug_hint(void *addr) |
515 | { |
516 | return ((struct work_struct *) addr)->func; |
517 | } |
518 | |
519 | static bool work_is_static_object(void *addr) |
520 | { |
521 | struct work_struct *work = addr; |
522 | |
523 | return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work)); |
524 | } |
525 | |
526 | /* |
527 | * fixup_init is called when: |
528 | * - an active object is initialized |
529 | */ |
530 | static bool work_fixup_init(void *addr, enum debug_obj_state state) |
531 | { |
532 | struct work_struct *work = addr; |
533 | |
534 | switch (state) { |
535 | case ODEBUG_STATE_ACTIVE: |
536 | cancel_work_sync(work); |
537 | debug_object_init(addr: work, descr: &work_debug_descr); |
538 | return true; |
539 | default: |
540 | return false; |
541 | } |
542 | } |
543 | |
544 | /* |
545 | * fixup_free is called when: |
546 | * - an active object is freed |
547 | */ |
548 | static bool work_fixup_free(void *addr, enum debug_obj_state state) |
549 | { |
550 | struct work_struct *work = addr; |
551 | |
552 | switch (state) { |
553 | case ODEBUG_STATE_ACTIVE: |
554 | cancel_work_sync(work); |
555 | debug_object_free(addr: work, descr: &work_debug_descr); |
556 | return true; |
557 | default: |
558 | return false; |
559 | } |
560 | } |
561 | |
562 | static const struct debug_obj_descr work_debug_descr = { |
563 | .name = "work_struct" , |
564 | .debug_hint = work_debug_hint, |
565 | .is_static_object = work_is_static_object, |
566 | .fixup_init = work_fixup_init, |
567 | .fixup_free = work_fixup_free, |
568 | }; |
569 | |
570 | static inline void debug_work_activate(struct work_struct *work) |
571 | { |
572 | debug_object_activate(addr: work, descr: &work_debug_descr); |
573 | } |
574 | |
575 | static inline void debug_work_deactivate(struct work_struct *work) |
576 | { |
577 | debug_object_deactivate(addr: work, descr: &work_debug_descr); |
578 | } |
579 | |
580 | void __init_work(struct work_struct *work, int onstack) |
581 | { |
582 | if (onstack) |
583 | debug_object_init_on_stack(addr: work, descr: &work_debug_descr); |
584 | else |
585 | debug_object_init(addr: work, descr: &work_debug_descr); |
586 | } |
587 | EXPORT_SYMBOL_GPL(__init_work); |
588 | |
589 | void destroy_work_on_stack(struct work_struct *work) |
590 | { |
591 | debug_object_free(addr: work, descr: &work_debug_descr); |
592 | } |
593 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
594 | |
595 | void destroy_delayed_work_on_stack(struct delayed_work *work) |
596 | { |
597 | destroy_timer_on_stack(timer: &work->timer); |
598 | debug_object_free(addr: &work->work, descr: &work_debug_descr); |
599 | } |
600 | EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); |
601 | |
602 | #else |
603 | static inline void debug_work_activate(struct work_struct *work) { } |
604 | static inline void debug_work_deactivate(struct work_struct *work) { } |
605 | #endif |
606 | |
607 | /** |
608 | * worker_pool_assign_id - allocate ID and assign it to @pool |
609 | * @pool: the pool pointer of interest |
610 | * |
611 | * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned |
612 | * successfully, -errno on failure. |
613 | */ |
614 | static int worker_pool_assign_id(struct worker_pool *pool) |
615 | { |
616 | int ret; |
617 | |
618 | lockdep_assert_held(&wq_pool_mutex); |
619 | |
620 | ret = idr_alloc(&worker_pool_idr, ptr: pool, start: 0, WORK_OFFQ_POOL_NONE, |
621 | GFP_KERNEL); |
622 | if (ret >= 0) { |
623 | pool->id = ret; |
624 | return 0; |
625 | } |
626 | return ret; |
627 | } |
628 | |
629 | static unsigned int work_color_to_flags(int color) |
630 | { |
631 | return color << WORK_STRUCT_COLOR_SHIFT; |
632 | } |
633 | |
634 | static int get_work_color(unsigned long work_data) |
635 | { |
636 | return (work_data >> WORK_STRUCT_COLOR_SHIFT) & |
637 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); |
638 | } |
639 | |
640 | static int work_next_color(int color) |
641 | { |
642 | return (color + 1) % WORK_NR_COLORS; |
643 | } |
644 | |
645 | /* |
646 | * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data |
647 | * contain the pointer to the queued pwq. Once execution starts, the flag |
648 | * is cleared and the high bits contain OFFQ flags and pool ID. |
649 | * |
650 | * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() |
651 | * and clear_work_data() can be used to set the pwq, pool or clear |
652 | * work->data. These functions should only be called while the work is |
653 | * owned - ie. while the PENDING bit is set. |
654 | * |
655 | * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq |
656 | * corresponding to a work. Pool is available once the work has been |
657 | * queued anywhere after initialization until it is sync canceled. pwq is |
658 | * available only while the work item is queued. |
659 | * |
660 | * %WORK_OFFQ_CANCELING is used to mark a work item which is being |
661 | * canceled. While being canceled, a work item may have its PENDING set |
662 | * but stay off timer and worklist for arbitrarily long and nobody should |
663 | * try to steal the PENDING bit. |
664 | */ |
665 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
666 | unsigned long flags) |
667 | { |
668 | WARN_ON_ONCE(!work_pending(work)); |
669 | atomic_long_set(v: &work->data, i: data | flags | work_static(work)); |
670 | } |
671 | |
672 | static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, |
673 | unsigned long ) |
674 | { |
675 | set_work_data(work, data: (unsigned long)pwq, |
676 | flags: WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); |
677 | } |
678 | |
679 | static void set_work_pool_and_keep_pending(struct work_struct *work, |
680 | int pool_id) |
681 | { |
682 | set_work_data(work, data: (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, |
683 | flags: WORK_STRUCT_PENDING); |
684 | } |
685 | |
686 | static void set_work_pool_and_clear_pending(struct work_struct *work, |
687 | int pool_id) |
688 | { |
689 | /* |
690 | * The following wmb is paired with the implied mb in |
691 | * test_and_set_bit(PENDING) and ensures all updates to @work made |
692 | * here are visible to and precede any updates by the next PENDING |
693 | * owner. |
694 | */ |
695 | smp_wmb(); |
696 | set_work_data(work, data: (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, flags: 0); |
697 | /* |
698 | * The following mb guarantees that previous clear of a PENDING bit |
699 | * will not be reordered with any speculative LOADS or STORES from |
700 | * work->current_func, which is executed afterwards. This possible |
701 | * reordering can lead to a missed execution on attempt to queue |
702 | * the same @work. E.g. consider this case: |
703 | * |
704 | * CPU#0 CPU#1 |
705 | * ---------------------------- -------------------------------- |
706 | * |
707 | * 1 STORE event_indicated |
708 | * 2 queue_work_on() { |
709 | * 3 test_and_set_bit(PENDING) |
710 | * 4 } set_..._and_clear_pending() { |
711 | * 5 set_work_data() # clear bit |
712 | * 6 smp_mb() |
713 | * 7 work->current_func() { |
714 | * 8 LOAD event_indicated |
715 | * } |
716 | * |
717 | * Without an explicit full barrier speculative LOAD on line 8 can |
718 | * be executed before CPU#0 does STORE on line 1. If that happens, |
719 | * CPU#0 observes the PENDING bit is still set and new execution of |
720 | * a @work is not queued in a hope, that CPU#1 will eventually |
721 | * finish the queued @work. Meanwhile CPU#1 does not see |
722 | * event_indicated is set, because speculative LOAD was executed |
723 | * before actual STORE. |
724 | */ |
725 | smp_mb(); |
726 | } |
727 | |
728 | static void clear_work_data(struct work_struct *work) |
729 | { |
730 | smp_wmb(); /* see set_work_pool_and_clear_pending() */ |
731 | set_work_data(work, WORK_STRUCT_NO_POOL, flags: 0); |
732 | } |
733 | |
734 | static inline struct pool_workqueue *work_struct_pwq(unsigned long data) |
735 | { |
736 | return (struct pool_workqueue *)(data & WORK_STRUCT_WQ_DATA_MASK); |
737 | } |
738 | |
739 | static struct pool_workqueue *get_work_pwq(struct work_struct *work) |
740 | { |
741 | unsigned long data = atomic_long_read(v: &work->data); |
742 | |
743 | if (data & WORK_STRUCT_PWQ) |
744 | return work_struct_pwq(data); |
745 | else |
746 | return NULL; |
747 | } |
748 | |
749 | /** |
750 | * get_work_pool - return the worker_pool a given work was associated with |
751 | * @work: the work item of interest |
752 | * |
753 | * Pools are created and destroyed under wq_pool_mutex, and allows read |
754 | * access under RCU read lock. As such, this function should be |
755 | * called under wq_pool_mutex or inside of a rcu_read_lock() region. |
756 | * |
757 | * All fields of the returned pool are accessible as long as the above |
758 | * mentioned locking is in effect. If the returned pool needs to be used |
759 | * beyond the critical section, the caller is responsible for ensuring the |
760 | * returned pool is and stays online. |
761 | * |
762 | * Return: The worker_pool @work was last associated with. %NULL if none. |
763 | */ |
764 | static struct worker_pool *get_work_pool(struct work_struct *work) |
765 | { |
766 | unsigned long data = atomic_long_read(v: &work->data); |
767 | int pool_id; |
768 | |
769 | assert_rcu_or_pool_mutex(); |
770 | |
771 | if (data & WORK_STRUCT_PWQ) |
772 | return work_struct_pwq(data)->pool; |
773 | |
774 | pool_id = data >> WORK_OFFQ_POOL_SHIFT; |
775 | if (pool_id == WORK_OFFQ_POOL_NONE) |
776 | return NULL; |
777 | |
778 | return idr_find(&worker_pool_idr, id: pool_id); |
779 | } |
780 | |
781 | /** |
782 | * get_work_pool_id - return the worker pool ID a given work is associated with |
783 | * @work: the work item of interest |
784 | * |
785 | * Return: The worker_pool ID @work was last associated with. |
786 | * %WORK_OFFQ_POOL_NONE if none. |
787 | */ |
788 | static int get_work_pool_id(struct work_struct *work) |
789 | { |
790 | unsigned long data = atomic_long_read(v: &work->data); |
791 | |
792 | if (data & WORK_STRUCT_PWQ) |
793 | return work_struct_pwq(data)->pool->id; |
794 | |
795 | return data >> WORK_OFFQ_POOL_SHIFT; |
796 | } |
797 | |
798 | static void mark_work_canceling(struct work_struct *work) |
799 | { |
800 | unsigned long pool_id = get_work_pool_id(work); |
801 | |
802 | pool_id <<= WORK_OFFQ_POOL_SHIFT; |
803 | set_work_data(work, data: pool_id | WORK_OFFQ_CANCELING, flags: WORK_STRUCT_PENDING); |
804 | } |
805 | |
806 | static bool work_is_canceling(struct work_struct *work) |
807 | { |
808 | unsigned long data = atomic_long_read(v: &work->data); |
809 | |
810 | return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); |
811 | } |
812 | |
813 | /* |
814 | * Policy functions. These define the policies on how the global worker |
815 | * pools are managed. Unless noted otherwise, these functions assume that |
816 | * they're being called with pool->lock held. |
817 | */ |
818 | |
819 | /* |
820 | * Need to wake up a worker? Called from anything but currently |
821 | * running workers. |
822 | * |
823 | * Note that, because unbound workers never contribute to nr_running, this |
824 | * function will always return %true for unbound pools as long as the |
825 | * worklist isn't empty. |
826 | */ |
827 | static bool need_more_worker(struct worker_pool *pool) |
828 | { |
829 | return !list_empty(head: &pool->worklist) && !pool->nr_running; |
830 | } |
831 | |
832 | /* Can I start working? Called from busy but !running workers. */ |
833 | static bool may_start_working(struct worker_pool *pool) |
834 | { |
835 | return pool->nr_idle; |
836 | } |
837 | |
838 | /* Do I need to keep working? Called from currently running workers. */ |
839 | static bool keep_working(struct worker_pool *pool) |
840 | { |
841 | return !list_empty(head: &pool->worklist) && (pool->nr_running <= 1); |
842 | } |
843 | |
844 | /* Do we need a new worker? Called from manager. */ |
845 | static bool need_to_create_worker(struct worker_pool *pool) |
846 | { |
847 | return need_more_worker(pool) && !may_start_working(pool); |
848 | } |
849 | |
850 | /* Do we have too many workers and should some go away? */ |
851 | static bool too_many_workers(struct worker_pool *pool) |
852 | { |
853 | bool managing = pool->flags & POOL_MANAGER_ACTIVE; |
854 | int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ |
855 | int nr_busy = pool->nr_workers - nr_idle; |
856 | |
857 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
858 | } |
859 | |
860 | /** |
861 | * worker_set_flags - set worker flags and adjust nr_running accordingly |
862 | * @worker: self |
863 | * @flags: flags to set |
864 | * |
865 | * Set @flags in @worker->flags and adjust nr_running accordingly. |
866 | */ |
867 | static inline void worker_set_flags(struct worker *worker, unsigned int flags) |
868 | { |
869 | struct worker_pool *pool = worker->pool; |
870 | |
871 | lockdep_assert_held(&pool->lock); |
872 | |
873 | /* If transitioning into NOT_RUNNING, adjust nr_running. */ |
874 | if ((flags & WORKER_NOT_RUNNING) && |
875 | !(worker->flags & WORKER_NOT_RUNNING)) { |
876 | pool->nr_running--; |
877 | } |
878 | |
879 | worker->flags |= flags; |
880 | } |
881 | |
882 | /** |
883 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
884 | * @worker: self |
885 | * @flags: flags to clear |
886 | * |
887 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
888 | */ |
889 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) |
890 | { |
891 | struct worker_pool *pool = worker->pool; |
892 | unsigned int oflags = worker->flags; |
893 | |
894 | lockdep_assert_held(&pool->lock); |
895 | |
896 | worker->flags &= ~flags; |
897 | |
898 | /* |
899 | * If transitioning out of NOT_RUNNING, increment nr_running. Note |
900 | * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask |
901 | * of multiple flags, not a single flag. |
902 | */ |
903 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
904 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
905 | pool->nr_running++; |
906 | } |
907 | |
908 | /* Return the first idle worker. Called with pool->lock held. */ |
909 | static struct worker *first_idle_worker(struct worker_pool *pool) |
910 | { |
911 | if (unlikely(list_empty(&pool->idle_list))) |
912 | return NULL; |
913 | |
914 | return list_first_entry(&pool->idle_list, struct worker, entry); |
915 | } |
916 | |
917 | /** |
918 | * worker_enter_idle - enter idle state |
919 | * @worker: worker which is entering idle state |
920 | * |
921 | * @worker is entering idle state. Update stats and idle timer if |
922 | * necessary. |
923 | * |
924 | * LOCKING: |
925 | * raw_spin_lock_irq(pool->lock). |
926 | */ |
927 | static void worker_enter_idle(struct worker *worker) |
928 | { |
929 | struct worker_pool *pool = worker->pool; |
930 | |
931 | if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || |
932 | WARN_ON_ONCE(!list_empty(&worker->entry) && |
933 | (worker->hentry.next || worker->hentry.pprev))) |
934 | return; |
935 | |
936 | /* can't use worker_set_flags(), also called from create_worker() */ |
937 | worker->flags |= WORKER_IDLE; |
938 | pool->nr_idle++; |
939 | worker->last_active = jiffies; |
940 | |
941 | /* idle_list is LIFO */ |
942 | list_add(new: &worker->entry, head: &pool->idle_list); |
943 | |
944 | if (too_many_workers(pool) && !timer_pending(timer: &pool->idle_timer)) |
945 | mod_timer(timer: &pool->idle_timer, expires: jiffies + IDLE_WORKER_TIMEOUT); |
946 | |
947 | /* Sanity check nr_running. */ |
948 | WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running); |
949 | } |
950 | |
951 | /** |
952 | * worker_leave_idle - leave idle state |
953 | * @worker: worker which is leaving idle state |
954 | * |
955 | * @worker is leaving idle state. Update stats. |
956 | * |
957 | * LOCKING: |
958 | * raw_spin_lock_irq(pool->lock). |
959 | */ |
960 | static void worker_leave_idle(struct worker *worker) |
961 | { |
962 | struct worker_pool *pool = worker->pool; |
963 | |
964 | if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) |
965 | return; |
966 | worker_clr_flags(worker, flags: WORKER_IDLE); |
967 | pool->nr_idle--; |
968 | list_del_init(entry: &worker->entry); |
969 | } |
970 | |
971 | /** |
972 | * find_worker_executing_work - find worker which is executing a work |
973 | * @pool: pool of interest |
974 | * @work: work to find worker for |
975 | * |
976 | * Find a worker which is executing @work on @pool by searching |
977 | * @pool->busy_hash which is keyed by the address of @work. For a worker |
978 | * to match, its current execution should match the address of @work and |
979 | * its work function. This is to avoid unwanted dependency between |
980 | * unrelated work executions through a work item being recycled while still |
981 | * being executed. |
982 | * |
983 | * This is a bit tricky. A work item may be freed once its execution |
984 | * starts and nothing prevents the freed area from being recycled for |
985 | * another work item. If the same work item address ends up being reused |
986 | * before the original execution finishes, workqueue will identify the |
987 | * recycled work item as currently executing and make it wait until the |
988 | * current execution finishes, introducing an unwanted dependency. |
989 | * |
990 | * This function checks the work item address and work function to avoid |
991 | * false positives. Note that this isn't complete as one may construct a |
992 | * work function which can introduce dependency onto itself through a |
993 | * recycled work item. Well, if somebody wants to shoot oneself in the |
994 | * foot that badly, there's only so much we can do, and if such deadlock |
995 | * actually occurs, it should be easy to locate the culprit work function. |
996 | * |
997 | * CONTEXT: |
998 | * raw_spin_lock_irq(pool->lock). |
999 | * |
1000 | * Return: |
1001 | * Pointer to worker which is executing @work if found, %NULL |
1002 | * otherwise. |
1003 | */ |
1004 | static struct worker *find_worker_executing_work(struct worker_pool *pool, |
1005 | struct work_struct *work) |
1006 | { |
1007 | struct worker *worker; |
1008 | |
1009 | hash_for_each_possible(pool->busy_hash, worker, hentry, |
1010 | (unsigned long)work) |
1011 | if (worker->current_work == work && |
1012 | worker->current_func == work->func) |
1013 | return worker; |
1014 | |
1015 | return NULL; |
1016 | } |
1017 | |
1018 | /** |
1019 | * move_linked_works - move linked works to a list |
1020 | * @work: start of series of works to be scheduled |
1021 | * @head: target list to append @work to |
1022 | * @nextp: out parameter for nested worklist walking |
1023 | * |
1024 | * Schedule linked works starting from @work to @head. Work series to be |
1025 | * scheduled starts at @work and includes any consecutive work with |
1026 | * WORK_STRUCT_LINKED set in its predecessor. See assign_work() for details on |
1027 | * @nextp. |
1028 | * |
1029 | * CONTEXT: |
1030 | * raw_spin_lock_irq(pool->lock). |
1031 | */ |
1032 | static void move_linked_works(struct work_struct *work, struct list_head *head, |
1033 | struct work_struct **nextp) |
1034 | { |
1035 | struct work_struct *n; |
1036 | |
1037 | /* |
1038 | * Linked worklist will always end before the end of the list, |
1039 | * use NULL for list head. |
1040 | */ |
1041 | list_for_each_entry_safe_from(work, n, NULL, entry) { |
1042 | list_move_tail(list: &work->entry, head); |
1043 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) |
1044 | break; |
1045 | } |
1046 | |
1047 | /* |
1048 | * If we're already inside safe list traversal and have moved |
1049 | * multiple works to the scheduled queue, the next position |
1050 | * needs to be updated. |
1051 | */ |
1052 | if (nextp) |
1053 | *nextp = n; |
1054 | } |
1055 | |
1056 | /** |
1057 | * assign_work - assign a work item and its linked work items to a worker |
1058 | * @work: work to assign |
1059 | * @worker: worker to assign to |
1060 | * @nextp: out parameter for nested worklist walking |
1061 | * |
1062 | * Assign @work and its linked work items to @worker. If @work is already being |
1063 | * executed by another worker in the same pool, it'll be punted there. |
1064 | * |
1065 | * If @nextp is not NULL, it's updated to point to the next work of the last |
1066 | * scheduled work. This allows assign_work() to be nested inside |
1067 | * list_for_each_entry_safe(). |
1068 | * |
1069 | * Returns %true if @work was successfully assigned to @worker. %false if @work |
1070 | * was punted to another worker already executing it. |
1071 | */ |
1072 | static bool assign_work(struct work_struct *work, struct worker *worker, |
1073 | struct work_struct **nextp) |
1074 | { |
1075 | struct worker_pool *pool = worker->pool; |
1076 | struct worker *collision; |
1077 | |
1078 | lockdep_assert_held(&pool->lock); |
1079 | |
1080 | /* |
1081 | * A single work shouldn't be executed concurrently by multiple workers. |
1082 | * __queue_work() ensures that @work doesn't jump to a different pool |
1083 | * while still running in the previous pool. Here, we should ensure that |
1084 | * @work is not executed concurrently by multiple workers from the same |
1085 | * pool. Check whether anyone is already processing the work. If so, |
1086 | * defer the work to the currently executing one. |
1087 | */ |
1088 | collision = find_worker_executing_work(pool, work); |
1089 | if (unlikely(collision)) { |
1090 | move_linked_works(work, head: &collision->scheduled, nextp); |
1091 | return false; |
1092 | } |
1093 | |
1094 | move_linked_works(work, head: &worker->scheduled, nextp); |
1095 | return true; |
1096 | } |
1097 | |
1098 | /** |
1099 | * kick_pool - wake up an idle worker if necessary |
1100 | * @pool: pool to kick |
1101 | * |
1102 | * @pool may have pending work items. Wake up worker if necessary. Returns |
1103 | * whether a worker was woken up. |
1104 | */ |
1105 | static bool kick_pool(struct worker_pool *pool) |
1106 | { |
1107 | struct worker *worker = first_idle_worker(pool); |
1108 | struct task_struct *p; |
1109 | |
1110 | lockdep_assert_held(&pool->lock); |
1111 | |
1112 | if (!need_more_worker(pool) || !worker) |
1113 | return false; |
1114 | |
1115 | p = worker->task; |
1116 | |
1117 | #ifdef CONFIG_SMP |
1118 | /* |
1119 | * Idle @worker is about to execute @work and waking up provides an |
1120 | * opportunity to migrate @worker at a lower cost by setting the task's |
1121 | * wake_cpu field. Let's see if we want to move @worker to improve |
1122 | * execution locality. |
1123 | * |
1124 | * We're waking the worker that went idle the latest and there's some |
1125 | * chance that @worker is marked idle but hasn't gone off CPU yet. If |
1126 | * so, setting the wake_cpu won't do anything. As this is a best-effort |
1127 | * optimization and the race window is narrow, let's leave as-is for |
1128 | * now. If this becomes pronounced, we can skip over workers which are |
1129 | * still on cpu when picking an idle worker. |
1130 | * |
1131 | * If @pool has non-strict affinity, @worker might have ended up outside |
1132 | * its affinity scope. Repatriate. |
1133 | */ |
1134 | if (!pool->attrs->affn_strict && |
1135 | !cpumask_test_cpu(cpu: p->wake_cpu, cpumask: pool->attrs->__pod_cpumask)) { |
1136 | struct work_struct *work = list_first_entry(&pool->worklist, |
1137 | struct work_struct, entry); |
1138 | p->wake_cpu = cpumask_any_distribute(srcp: pool->attrs->__pod_cpumask); |
1139 | get_work_pwq(work)->stats[PWQ_STAT_REPATRIATED]++; |
1140 | } |
1141 | #endif |
1142 | wake_up_process(tsk: p); |
1143 | return true; |
1144 | } |
1145 | |
1146 | #ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT |
1147 | |
1148 | /* |
1149 | * Concurrency-managed per-cpu work items that hog CPU for longer than |
1150 | * wq_cpu_intensive_thresh_us trigger the automatic CPU_INTENSIVE mechanism, |
1151 | * which prevents them from stalling other concurrency-managed work items. If a |
1152 | * work function keeps triggering this mechanism, it's likely that the work item |
1153 | * should be using an unbound workqueue instead. |
1154 | * |
1155 | * wq_cpu_intensive_report() tracks work functions which trigger such conditions |
1156 | * and report them so that they can be examined and converted to use unbound |
1157 | * workqueues as appropriate. To avoid flooding the console, each violating work |
1158 | * function is tracked and reported with exponential backoff. |
1159 | */ |
1160 | #define WCI_MAX_ENTS 128 |
1161 | |
1162 | struct wci_ent { |
1163 | work_func_t func; |
1164 | atomic64_t cnt; |
1165 | struct hlist_node hash_node; |
1166 | }; |
1167 | |
1168 | static struct wci_ent wci_ents[WCI_MAX_ENTS]; |
1169 | static int wci_nr_ents; |
1170 | static DEFINE_RAW_SPINLOCK(wci_lock); |
1171 | static DEFINE_HASHTABLE(wci_hash, ilog2(WCI_MAX_ENTS)); |
1172 | |
1173 | static struct wci_ent *wci_find_ent(work_func_t func) |
1174 | { |
1175 | struct wci_ent *ent; |
1176 | |
1177 | hash_for_each_possible_rcu(wci_hash, ent, hash_node, |
1178 | (unsigned long)func) { |
1179 | if (ent->func == func) |
1180 | return ent; |
1181 | } |
1182 | return NULL; |
1183 | } |
1184 | |
1185 | static void wq_cpu_intensive_report(work_func_t func) |
1186 | { |
1187 | struct wci_ent *ent; |
1188 | |
1189 | restart: |
1190 | ent = wci_find_ent(func); |
1191 | if (ent) { |
1192 | u64 cnt; |
1193 | |
1194 | /* |
1195 | * Start reporting from the fourth time and back off |
1196 | * exponentially. |
1197 | */ |
1198 | cnt = atomic64_inc_return_relaxed(v: &ent->cnt); |
1199 | if (cnt >= 4 && is_power_of_2(n: cnt)) |
1200 | printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching to WQ_UNBOUND\n" , |
1201 | ent->func, wq_cpu_intensive_thresh_us, |
1202 | atomic64_read(&ent->cnt)); |
1203 | return; |
1204 | } |
1205 | |
1206 | /* |
1207 | * @func is a new violation. Allocate a new entry for it. If wcn_ents[] |
1208 | * is exhausted, something went really wrong and we probably made enough |
1209 | * noise already. |
1210 | */ |
1211 | if (wci_nr_ents >= WCI_MAX_ENTS) |
1212 | return; |
1213 | |
1214 | raw_spin_lock(&wci_lock); |
1215 | |
1216 | if (wci_nr_ents >= WCI_MAX_ENTS) { |
1217 | raw_spin_unlock(&wci_lock); |
1218 | return; |
1219 | } |
1220 | |
1221 | if (wci_find_ent(func)) { |
1222 | raw_spin_unlock(&wci_lock); |
1223 | goto restart; |
1224 | } |
1225 | |
1226 | ent = &wci_ents[wci_nr_ents++]; |
1227 | ent->func = func; |
1228 | atomic64_set(v: &ent->cnt, i: 1); |
1229 | hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func); |
1230 | |
1231 | raw_spin_unlock(&wci_lock); |
1232 | } |
1233 | |
1234 | #else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ |
1235 | static void wq_cpu_intensive_report(work_func_t func) {} |
1236 | #endif /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ |
1237 | |
1238 | /** |
1239 | * wq_worker_running - a worker is running again |
1240 | * @task: task waking up |
1241 | * |
1242 | * This function is called when a worker returns from schedule() |
1243 | */ |
1244 | void wq_worker_running(struct task_struct *task) |
1245 | { |
1246 | struct worker *worker = kthread_data(k: task); |
1247 | |
1248 | if (!READ_ONCE(worker->sleeping)) |
1249 | return; |
1250 | |
1251 | /* |
1252 | * If preempted by unbind_workers() between the WORKER_NOT_RUNNING check |
1253 | * and the nr_running increment below, we may ruin the nr_running reset |
1254 | * and leave with an unexpected pool->nr_running == 1 on the newly unbound |
1255 | * pool. Protect against such race. |
1256 | */ |
1257 | preempt_disable(); |
1258 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
1259 | worker->pool->nr_running++; |
1260 | preempt_enable(); |
1261 | |
1262 | /* |
1263 | * CPU intensive auto-detection cares about how long a work item hogged |
1264 | * CPU without sleeping. Reset the starting timestamp on wakeup. |
1265 | */ |
1266 | worker->current_at = worker->task->se.sum_exec_runtime; |
1267 | |
1268 | WRITE_ONCE(worker->sleeping, 0); |
1269 | } |
1270 | |
1271 | /** |
1272 | * wq_worker_sleeping - a worker is going to sleep |
1273 | * @task: task going to sleep |
1274 | * |
1275 | * This function is called from schedule() when a busy worker is |
1276 | * going to sleep. |
1277 | */ |
1278 | void wq_worker_sleeping(struct task_struct *task) |
1279 | { |
1280 | struct worker *worker = kthread_data(k: task); |
1281 | struct worker_pool *pool; |
1282 | |
1283 | /* |
1284 | * Rescuers, which may not have all the fields set up like normal |
1285 | * workers, also reach here, let's not access anything before |
1286 | * checking NOT_RUNNING. |
1287 | */ |
1288 | if (worker->flags & WORKER_NOT_RUNNING) |
1289 | return; |
1290 | |
1291 | pool = worker->pool; |
1292 | |
1293 | /* Return if preempted before wq_worker_running() was reached */ |
1294 | if (READ_ONCE(worker->sleeping)) |
1295 | return; |
1296 | |
1297 | WRITE_ONCE(worker->sleeping, 1); |
1298 | raw_spin_lock_irq(&pool->lock); |
1299 | |
1300 | /* |
1301 | * Recheck in case unbind_workers() preempted us. We don't |
1302 | * want to decrement nr_running after the worker is unbound |
1303 | * and nr_running has been reset. |
1304 | */ |
1305 | if (worker->flags & WORKER_NOT_RUNNING) { |
1306 | raw_spin_unlock_irq(&pool->lock); |
1307 | return; |
1308 | } |
1309 | |
1310 | pool->nr_running--; |
1311 | if (kick_pool(pool)) |
1312 | worker->current_pwq->stats[PWQ_STAT_CM_WAKEUP]++; |
1313 | |
1314 | raw_spin_unlock_irq(&pool->lock); |
1315 | } |
1316 | |
1317 | /** |
1318 | * wq_worker_tick - a scheduler tick occurred while a kworker is running |
1319 | * @task: task currently running |
1320 | * |
1321 | * Called from scheduler_tick(). We're in the IRQ context and the current |
1322 | * worker's fields which follow the 'K' locking rule can be accessed safely. |
1323 | */ |
1324 | void wq_worker_tick(struct task_struct *task) |
1325 | { |
1326 | struct worker *worker = kthread_data(k: task); |
1327 | struct pool_workqueue *pwq = worker->current_pwq; |
1328 | struct worker_pool *pool = worker->pool; |
1329 | |
1330 | if (!pwq) |
1331 | return; |
1332 | |
1333 | pwq->stats[PWQ_STAT_CPU_TIME] += TICK_USEC; |
1334 | |
1335 | if (!wq_cpu_intensive_thresh_us) |
1336 | return; |
1337 | |
1338 | /* |
1339 | * If the current worker is concurrency managed and hogged the CPU for |
1340 | * longer than wq_cpu_intensive_thresh_us, it's automatically marked |
1341 | * CPU_INTENSIVE to avoid stalling other concurrency-managed work items. |
1342 | * |
1343 | * Set @worker->sleeping means that @worker is in the process of |
1344 | * switching out voluntarily and won't be contributing to |
1345 | * @pool->nr_running until it wakes up. As wq_worker_sleeping() also |
1346 | * decrements ->nr_running, setting CPU_INTENSIVE here can lead to |
1347 | * double decrements. The task is releasing the CPU anyway. Let's skip. |
1348 | * We probably want to make this prettier in the future. |
1349 | */ |
1350 | if ((worker->flags & WORKER_NOT_RUNNING) || READ_ONCE(worker->sleeping) || |
1351 | worker->task->se.sum_exec_runtime - worker->current_at < |
1352 | wq_cpu_intensive_thresh_us * NSEC_PER_USEC) |
1353 | return; |
1354 | |
1355 | raw_spin_lock(&pool->lock); |
1356 | |
1357 | worker_set_flags(worker, flags: WORKER_CPU_INTENSIVE); |
1358 | wq_cpu_intensive_report(func: worker->current_func); |
1359 | pwq->stats[PWQ_STAT_CPU_INTENSIVE]++; |
1360 | |
1361 | if (kick_pool(pool)) |
1362 | pwq->stats[PWQ_STAT_CM_WAKEUP]++; |
1363 | |
1364 | raw_spin_unlock(&pool->lock); |
1365 | } |
1366 | |
1367 | /** |
1368 | * wq_worker_last_func - retrieve worker's last work function |
1369 | * @task: Task to retrieve last work function of. |
1370 | * |
1371 | * Determine the last function a worker executed. This is called from |
1372 | * the scheduler to get a worker's last known identity. |
1373 | * |
1374 | * CONTEXT: |
1375 | * raw_spin_lock_irq(rq->lock) |
1376 | * |
1377 | * This function is called during schedule() when a kworker is going |
1378 | * to sleep. It's used by psi to identify aggregation workers during |
1379 | * dequeuing, to allow periodic aggregation to shut-off when that |
1380 | * worker is the last task in the system or cgroup to go to sleep. |
1381 | * |
1382 | * As this function doesn't involve any workqueue-related locking, it |
1383 | * only returns stable values when called from inside the scheduler's |
1384 | * queuing and dequeuing paths, when @task, which must be a kworker, |
1385 | * is guaranteed to not be processing any works. |
1386 | * |
1387 | * Return: |
1388 | * The last work function %current executed as a worker, NULL if it |
1389 | * hasn't executed any work yet. |
1390 | */ |
1391 | work_func_t wq_worker_last_func(struct task_struct *task) |
1392 | { |
1393 | struct worker *worker = kthread_data(k: task); |
1394 | |
1395 | return worker->last_func; |
1396 | } |
1397 | |
1398 | /** |
1399 | * get_pwq - get an extra reference on the specified pool_workqueue |
1400 | * @pwq: pool_workqueue to get |
1401 | * |
1402 | * Obtain an extra reference on @pwq. The caller should guarantee that |
1403 | * @pwq has positive refcnt and be holding the matching pool->lock. |
1404 | */ |
1405 | static void get_pwq(struct pool_workqueue *pwq) |
1406 | { |
1407 | lockdep_assert_held(&pwq->pool->lock); |
1408 | WARN_ON_ONCE(pwq->refcnt <= 0); |
1409 | pwq->refcnt++; |
1410 | } |
1411 | |
1412 | /** |
1413 | * put_pwq - put a pool_workqueue reference |
1414 | * @pwq: pool_workqueue to put |
1415 | * |
1416 | * Drop a reference of @pwq. If its refcnt reaches zero, schedule its |
1417 | * destruction. The caller should be holding the matching pool->lock. |
1418 | */ |
1419 | static void put_pwq(struct pool_workqueue *pwq) |
1420 | { |
1421 | lockdep_assert_held(&pwq->pool->lock); |
1422 | if (likely(--pwq->refcnt)) |
1423 | return; |
1424 | /* |
1425 | * @pwq can't be released under pool->lock, bounce to a dedicated |
1426 | * kthread_worker to avoid A-A deadlocks. |
1427 | */ |
1428 | kthread_queue_work(worker: pwq_release_worker, work: &pwq->release_work); |
1429 | } |
1430 | |
1431 | /** |
1432 | * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock |
1433 | * @pwq: pool_workqueue to put (can be %NULL) |
1434 | * |
1435 | * put_pwq() with locking. This function also allows %NULL @pwq. |
1436 | */ |
1437 | static void put_pwq_unlocked(struct pool_workqueue *pwq) |
1438 | { |
1439 | if (pwq) { |
1440 | /* |
1441 | * As both pwqs and pools are RCU protected, the |
1442 | * following lock operations are safe. |
1443 | */ |
1444 | raw_spin_lock_irq(&pwq->pool->lock); |
1445 | put_pwq(pwq); |
1446 | raw_spin_unlock_irq(&pwq->pool->lock); |
1447 | } |
1448 | } |
1449 | |
1450 | static void pwq_activate_inactive_work(struct work_struct *work) |
1451 | { |
1452 | struct pool_workqueue *pwq = get_work_pwq(work); |
1453 | |
1454 | trace_workqueue_activate_work(work); |
1455 | if (list_empty(head: &pwq->pool->worklist)) |
1456 | pwq->pool->watchdog_ts = jiffies; |
1457 | move_linked_works(work, head: &pwq->pool->worklist, NULL); |
1458 | __clear_bit(WORK_STRUCT_INACTIVE_BIT, work_data_bits(work)); |
1459 | pwq->nr_active++; |
1460 | } |
1461 | |
1462 | static void pwq_activate_first_inactive(struct pool_workqueue *pwq) |
1463 | { |
1464 | struct work_struct *work = list_first_entry(&pwq->inactive_works, |
1465 | struct work_struct, entry); |
1466 | |
1467 | pwq_activate_inactive_work(work); |
1468 | } |
1469 | |
1470 | /** |
1471 | * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight |
1472 | * @pwq: pwq of interest |
1473 | * @work_data: work_data of work which left the queue |
1474 | * |
1475 | * A work either has completed or is removed from pending queue, |
1476 | * decrement nr_in_flight of its pwq and handle workqueue flushing. |
1477 | * |
1478 | * CONTEXT: |
1479 | * raw_spin_lock_irq(pool->lock). |
1480 | */ |
1481 | static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data) |
1482 | { |
1483 | int color = get_work_color(work_data); |
1484 | |
1485 | if (!(work_data & WORK_STRUCT_INACTIVE)) { |
1486 | pwq->nr_active--; |
1487 | if (!list_empty(head: &pwq->inactive_works)) { |
1488 | /* one down, submit an inactive one */ |
1489 | if (pwq->nr_active < pwq->max_active) |
1490 | pwq_activate_first_inactive(pwq); |
1491 | } |
1492 | } |
1493 | |
1494 | pwq->nr_in_flight[color]--; |
1495 | |
1496 | /* is flush in progress and are we at the flushing tip? */ |
1497 | if (likely(pwq->flush_color != color)) |
1498 | goto out_put; |
1499 | |
1500 | /* are there still in-flight works? */ |
1501 | if (pwq->nr_in_flight[color]) |
1502 | goto out_put; |
1503 | |
1504 | /* this pwq is done, clear flush_color */ |
1505 | pwq->flush_color = -1; |
1506 | |
1507 | /* |
1508 | * If this was the last pwq, wake up the first flusher. It |
1509 | * will handle the rest. |
1510 | */ |
1511 | if (atomic_dec_and_test(v: &pwq->wq->nr_pwqs_to_flush)) |
1512 | complete(&pwq->wq->first_flusher->done); |
1513 | out_put: |
1514 | put_pwq(pwq); |
1515 | } |
1516 | |
1517 | /** |
1518 | * try_to_grab_pending - steal work item from worklist and disable irq |
1519 | * @work: work item to steal |
1520 | * @is_dwork: @work is a delayed_work |
1521 | * @flags: place to store irq state |
1522 | * |
1523 | * Try to grab PENDING bit of @work. This function can handle @work in any |
1524 | * stable state - idle, on timer or on worklist. |
1525 | * |
1526 | * Return: |
1527 | * |
1528 | * ======== ================================================================ |
1529 | * 1 if @work was pending and we successfully stole PENDING |
1530 | * 0 if @work was idle and we claimed PENDING |
1531 | * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry |
1532 | * -ENOENT if someone else is canceling @work, this state may persist |
1533 | * for arbitrarily long |
1534 | * ======== ================================================================ |
1535 | * |
1536 | * Note: |
1537 | * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting |
1538 | * interrupted while holding PENDING and @work off queue, irq must be |
1539 | * disabled on entry. This, combined with delayed_work->timer being |
1540 | * irqsafe, ensures that we return -EAGAIN for finite short period of time. |
1541 | * |
1542 | * On successful return, >= 0, irq is disabled and the caller is |
1543 | * responsible for releasing it using local_irq_restore(*@flags). |
1544 | * |
1545 | * This function is safe to call from any context including IRQ handler. |
1546 | */ |
1547 | static int try_to_grab_pending(struct work_struct *work, bool is_dwork, |
1548 | unsigned long *flags) |
1549 | { |
1550 | struct worker_pool *pool; |
1551 | struct pool_workqueue *pwq; |
1552 | |
1553 | local_irq_save(*flags); |
1554 | |
1555 | /* try to steal the timer if it exists */ |
1556 | if (is_dwork) { |
1557 | struct delayed_work *dwork = to_delayed_work(work); |
1558 | |
1559 | /* |
1560 | * dwork->timer is irqsafe. If del_timer() fails, it's |
1561 | * guaranteed that the timer is not queued anywhere and not |
1562 | * running on the local CPU. |
1563 | */ |
1564 | if (likely(del_timer(&dwork->timer))) |
1565 | return 1; |
1566 | } |
1567 | |
1568 | /* try to claim PENDING the normal way */ |
1569 | if (!test_and_set_bit(nr: WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
1570 | return 0; |
1571 | |
1572 | rcu_read_lock(); |
1573 | /* |
1574 | * The queueing is in progress, or it is already queued. Try to |
1575 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. |
1576 | */ |
1577 | pool = get_work_pool(work); |
1578 | if (!pool) |
1579 | goto fail; |
1580 | |
1581 | raw_spin_lock(&pool->lock); |
1582 | /* |
1583 | * work->data is guaranteed to point to pwq only while the work |
1584 | * item is queued on pwq->wq, and both updating work->data to point |
1585 | * to pwq on queueing and to pool on dequeueing are done under |
1586 | * pwq->pool->lock. This in turn guarantees that, if work->data |
1587 | * points to pwq which is associated with a locked pool, the work |
1588 | * item is currently queued on that pool. |
1589 | */ |
1590 | pwq = get_work_pwq(work); |
1591 | if (pwq && pwq->pool == pool) { |
1592 | debug_work_deactivate(work); |
1593 | |
1594 | /* |
1595 | * A cancelable inactive work item must be in the |
1596 | * pwq->inactive_works since a queued barrier can't be |
1597 | * canceled (see the comments in insert_wq_barrier()). |
1598 | * |
1599 | * An inactive work item cannot be grabbed directly because |
1600 | * it might have linked barrier work items which, if left |
1601 | * on the inactive_works list, will confuse pwq->nr_active |
1602 | * management later on and cause stall. Make sure the work |
1603 | * item is activated before grabbing. |
1604 | */ |
1605 | if (*work_data_bits(work) & WORK_STRUCT_INACTIVE) |
1606 | pwq_activate_inactive_work(work); |
1607 | |
1608 | list_del_init(entry: &work->entry); |
1609 | pwq_dec_nr_in_flight(pwq, work_data: *work_data_bits(work)); |
1610 | |
1611 | /* work->data points to pwq iff queued, point to pool */ |
1612 | set_work_pool_and_keep_pending(work, pool_id: pool->id); |
1613 | |
1614 | raw_spin_unlock(&pool->lock); |
1615 | rcu_read_unlock(); |
1616 | return 1; |
1617 | } |
1618 | raw_spin_unlock(&pool->lock); |
1619 | fail: |
1620 | rcu_read_unlock(); |
1621 | local_irq_restore(*flags); |
1622 | if (work_is_canceling(work)) |
1623 | return -ENOENT; |
1624 | cpu_relax(); |
1625 | return -EAGAIN; |
1626 | } |
1627 | |
1628 | /** |
1629 | * insert_work - insert a work into a pool |
1630 | * @pwq: pwq @work belongs to |
1631 | * @work: work to insert |
1632 | * @head: insertion point |
1633 | * @extra_flags: extra WORK_STRUCT_* flags to set |
1634 | * |
1635 | * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to |
1636 | * work_struct flags. |
1637 | * |
1638 | * CONTEXT: |
1639 | * raw_spin_lock_irq(pool->lock). |
1640 | */ |
1641 | static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, |
1642 | struct list_head *head, unsigned int ) |
1643 | { |
1644 | debug_work_activate(work); |
1645 | |
1646 | /* record the work call stack in order to print it in KASAN reports */ |
1647 | kasan_record_aux_stack_noalloc(ptr: work); |
1648 | |
1649 | /* we own @work, set data and link */ |
1650 | set_work_pwq(work, pwq, extra_flags); |
1651 | list_add_tail(new: &work->entry, head); |
1652 | get_pwq(pwq); |
1653 | } |
1654 | |
1655 | /* |
1656 | * Test whether @work is being queued from another work executing on the |
1657 | * same workqueue. |
1658 | */ |
1659 | static bool is_chained_work(struct workqueue_struct *wq) |
1660 | { |
1661 | struct worker *worker; |
1662 | |
1663 | worker = current_wq_worker(); |
1664 | /* |
1665 | * Return %true iff I'm a worker executing a work item on @wq. If |
1666 | * I'm @worker, it's safe to dereference it without locking. |
1667 | */ |
1668 | return worker && worker->current_pwq->wq == wq; |
1669 | } |
1670 | |
1671 | /* |
1672 | * When queueing an unbound work item to a wq, prefer local CPU if allowed |
1673 | * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to |
1674 | * avoid perturbing sensitive tasks. |
1675 | */ |
1676 | static int wq_select_unbound_cpu(int cpu) |
1677 | { |
1678 | int new_cpu; |
1679 | |
1680 | if (likely(!wq_debug_force_rr_cpu)) { |
1681 | if (cpumask_test_cpu(cpu, cpumask: wq_unbound_cpumask)) |
1682 | return cpu; |
1683 | } else { |
1684 | pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n" ); |
1685 | } |
1686 | |
1687 | if (cpumask_empty(srcp: wq_unbound_cpumask)) |
1688 | return cpu; |
1689 | |
1690 | new_cpu = __this_cpu_read(wq_rr_cpu_last); |
1691 | new_cpu = cpumask_next_and(n: new_cpu, src1p: wq_unbound_cpumask, cpu_online_mask); |
1692 | if (unlikely(new_cpu >= nr_cpu_ids)) { |
1693 | new_cpu = cpumask_first_and(srcp1: wq_unbound_cpumask, cpu_online_mask); |
1694 | if (unlikely(new_cpu >= nr_cpu_ids)) |
1695 | return cpu; |
1696 | } |
1697 | __this_cpu_write(wq_rr_cpu_last, new_cpu); |
1698 | |
1699 | return new_cpu; |
1700 | } |
1701 | |
1702 | static void __queue_work(int cpu, struct workqueue_struct *wq, |
1703 | struct work_struct *work) |
1704 | { |
1705 | struct pool_workqueue *pwq; |
1706 | struct worker_pool *last_pool, *pool; |
1707 | unsigned int work_flags; |
1708 | unsigned int req_cpu = cpu; |
1709 | |
1710 | /* |
1711 | * While a work item is PENDING && off queue, a task trying to |
1712 | * steal the PENDING will busy-loop waiting for it to either get |
1713 | * queued or lose PENDING. Grabbing PENDING and queueing should |
1714 | * happen with IRQ disabled. |
1715 | */ |
1716 | lockdep_assert_irqs_disabled(); |
1717 | |
1718 | |
1719 | /* |
1720 | * For a draining wq, only works from the same workqueue are |
1721 | * allowed. The __WQ_DESTROYING helps to spot the issue that |
1722 | * queues a new work item to a wq after destroy_workqueue(wq). |
1723 | */ |
1724 | if (unlikely(wq->flags & (__WQ_DESTROYING | __WQ_DRAINING) && |
1725 | WARN_ON_ONCE(!is_chained_work(wq)))) |
1726 | return; |
1727 | rcu_read_lock(); |
1728 | retry: |
1729 | /* pwq which will be used unless @work is executing elsewhere */ |
1730 | if (req_cpu == WORK_CPU_UNBOUND) { |
1731 | if (wq->flags & WQ_UNBOUND) |
1732 | cpu = wq_select_unbound_cpu(raw_smp_processor_id()); |
1733 | else |
1734 | cpu = raw_smp_processor_id(); |
1735 | } |
1736 | |
1737 | pwq = rcu_dereference(*per_cpu_ptr(wq->cpu_pwq, cpu)); |
1738 | pool = pwq->pool; |
1739 | |
1740 | /* |
1741 | * If @work was previously on a different pool, it might still be |
1742 | * running there, in which case the work needs to be queued on that |
1743 | * pool to guarantee non-reentrancy. |
1744 | */ |
1745 | last_pool = get_work_pool(work); |
1746 | if (last_pool && last_pool != pool) { |
1747 | struct worker *worker; |
1748 | |
1749 | raw_spin_lock(&last_pool->lock); |
1750 | |
1751 | worker = find_worker_executing_work(pool: last_pool, work); |
1752 | |
1753 | if (worker && worker->current_pwq->wq == wq) { |
1754 | pwq = worker->current_pwq; |
1755 | pool = pwq->pool; |
1756 | WARN_ON_ONCE(pool != last_pool); |
1757 | } else { |
1758 | /* meh... not running there, queue here */ |
1759 | raw_spin_unlock(&last_pool->lock); |
1760 | raw_spin_lock(&pool->lock); |
1761 | } |
1762 | } else { |
1763 | raw_spin_lock(&pool->lock); |
1764 | } |
1765 | |
1766 | /* |
1767 | * pwq is determined and locked. For unbound pools, we could have raced |
1768 | * with pwq release and it could already be dead. If its refcnt is zero, |
1769 | * repeat pwq selection. Note that unbound pwqs never die without |
1770 | * another pwq replacing it in cpu_pwq or while work items are executing |
1771 | * on it, so the retrying is guaranteed to make forward-progress. |
1772 | */ |
1773 | if (unlikely(!pwq->refcnt)) { |
1774 | if (wq->flags & WQ_UNBOUND) { |
1775 | raw_spin_unlock(&pool->lock); |
1776 | cpu_relax(); |
1777 | goto retry; |
1778 | } |
1779 | /* oops */ |
1780 | WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt" , |
1781 | wq->name, cpu); |
1782 | } |
1783 | |
1784 | /* pwq determined, queue */ |
1785 | trace_workqueue_queue_work(req_cpu, pwq, work); |
1786 | |
1787 | if (WARN_ON(!list_empty(&work->entry))) |
1788 | goto out; |
1789 | |
1790 | pwq->nr_in_flight[pwq->work_color]++; |
1791 | work_flags = work_color_to_flags(color: pwq->work_color); |
1792 | |
1793 | if (likely(pwq->nr_active < pwq->max_active)) { |
1794 | if (list_empty(head: &pool->worklist)) |
1795 | pool->watchdog_ts = jiffies; |
1796 | |
1797 | trace_workqueue_activate_work(work); |
1798 | pwq->nr_active++; |
1799 | insert_work(pwq, work, head: &pool->worklist, extra_flags: work_flags); |
1800 | kick_pool(pool); |
1801 | } else { |
1802 | work_flags |= WORK_STRUCT_INACTIVE; |
1803 | insert_work(pwq, work, head: &pwq->inactive_works, extra_flags: work_flags); |
1804 | } |
1805 | |
1806 | out: |
1807 | raw_spin_unlock(&pool->lock); |
1808 | rcu_read_unlock(); |
1809 | } |
1810 | |
1811 | /** |
1812 | * queue_work_on - queue work on specific cpu |
1813 | * @cpu: CPU number to execute work on |
1814 | * @wq: workqueue to use |
1815 | * @work: work to queue |
1816 | * |
1817 | * We queue the work to a specific CPU, the caller must ensure it |
1818 | * can't go away. Callers that fail to ensure that the specified |
1819 | * CPU cannot go away will execute on a randomly chosen CPU. |
1820 | * But note well that callers specifying a CPU that never has been |
1821 | * online will get a splat. |
1822 | * |
1823 | * Return: %false if @work was already on a queue, %true otherwise. |
1824 | */ |
1825 | bool queue_work_on(int cpu, struct workqueue_struct *wq, |
1826 | struct work_struct *work) |
1827 | { |
1828 | bool ret = false; |
1829 | unsigned long flags; |
1830 | |
1831 | local_irq_save(flags); |
1832 | |
1833 | if (!test_and_set_bit(nr: WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1834 | __queue_work(cpu, wq, work); |
1835 | ret = true; |
1836 | } |
1837 | |
1838 | local_irq_restore(flags); |
1839 | return ret; |
1840 | } |
1841 | EXPORT_SYMBOL(queue_work_on); |
1842 | |
1843 | /** |
1844 | * select_numa_node_cpu - Select a CPU based on NUMA node |
1845 | * @node: NUMA node ID that we want to select a CPU from |
1846 | * |
1847 | * This function will attempt to find a "random" cpu available on a given |
1848 | * node. If there are no CPUs available on the given node it will return |
1849 | * WORK_CPU_UNBOUND indicating that we should just schedule to any |
1850 | * available CPU if we need to schedule this work. |
1851 | */ |
1852 | static int select_numa_node_cpu(int node) |
1853 | { |
1854 | int cpu; |
1855 | |
1856 | /* Delay binding to CPU if node is not valid or online */ |
1857 | if (node < 0 || node >= MAX_NUMNODES || !node_online(node)) |
1858 | return WORK_CPU_UNBOUND; |
1859 | |
1860 | /* Use local node/cpu if we are already there */ |
1861 | cpu = raw_smp_processor_id(); |
1862 | if (node == cpu_to_node(cpu)) |
1863 | return cpu; |
1864 | |
1865 | /* Use "random" otherwise know as "first" online CPU of node */ |
1866 | cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask); |
1867 | |
1868 | /* If CPU is valid return that, otherwise just defer */ |
1869 | return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND; |
1870 | } |
1871 | |
1872 | /** |
1873 | * queue_work_node - queue work on a "random" cpu for a given NUMA node |
1874 | * @node: NUMA node that we are targeting the work for |
1875 | * @wq: workqueue to use |
1876 | * @work: work to queue |
1877 | * |
1878 | * We queue the work to a "random" CPU within a given NUMA node. The basic |
1879 | * idea here is to provide a way to somehow associate work with a given |
1880 | * NUMA node. |
1881 | * |
1882 | * This function will only make a best effort attempt at getting this onto |
1883 | * the right NUMA node. If no node is requested or the requested node is |
1884 | * offline then we just fall back to standard queue_work behavior. |
1885 | * |
1886 | * Currently the "random" CPU ends up being the first available CPU in the |
1887 | * intersection of cpu_online_mask and the cpumask of the node, unless we |
1888 | * are running on the node. In that case we just use the current CPU. |
1889 | * |
1890 | * Return: %false if @work was already on a queue, %true otherwise. |
1891 | */ |
1892 | bool queue_work_node(int node, struct workqueue_struct *wq, |
1893 | struct work_struct *work) |
1894 | { |
1895 | unsigned long flags; |
1896 | bool ret = false; |
1897 | |
1898 | /* |
1899 | * This current implementation is specific to unbound workqueues. |
1900 | * Specifically we only return the first available CPU for a given |
1901 | * node instead of cycling through individual CPUs within the node. |
1902 | * |
1903 | * If this is used with a per-cpu workqueue then the logic in |
1904 | * workqueue_select_cpu_near would need to be updated to allow for |
1905 | * some round robin type logic. |
1906 | */ |
1907 | WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)); |
1908 | |
1909 | local_irq_save(flags); |
1910 | |
1911 | if (!test_and_set_bit(nr: WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1912 | int cpu = select_numa_node_cpu(node); |
1913 | |
1914 | __queue_work(cpu, wq, work); |
1915 | ret = true; |
1916 | } |
1917 | |
1918 | local_irq_restore(flags); |
1919 | return ret; |
1920 | } |
1921 | EXPORT_SYMBOL_GPL(queue_work_node); |
1922 | |
1923 | void delayed_work_timer_fn(struct timer_list *t) |
1924 | { |
1925 | struct delayed_work *dwork = from_timer(dwork, t, timer); |
1926 | |
1927 | /* should have been called from irqsafe timer with irq already off */ |
1928 | __queue_work(cpu: dwork->cpu, wq: dwork->wq, work: &dwork->work); |
1929 | } |
1930 | EXPORT_SYMBOL(delayed_work_timer_fn); |
1931 | |
1932 | static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, |
1933 | struct delayed_work *dwork, unsigned long delay) |
1934 | { |
1935 | struct timer_list *timer = &dwork->timer; |
1936 | struct work_struct *work = &dwork->work; |
1937 | |
1938 | WARN_ON_ONCE(!wq); |
1939 | WARN_ON_ONCE(timer->function != delayed_work_timer_fn); |
1940 | WARN_ON_ONCE(timer_pending(timer)); |
1941 | WARN_ON_ONCE(!list_empty(&work->entry)); |
1942 | |
1943 | /* |
1944 | * If @delay is 0, queue @dwork->work immediately. This is for |
1945 | * both optimization and correctness. The earliest @timer can |
1946 | * expire is on the closest next tick and delayed_work users depend |
1947 | * on that there's no such delay when @delay is 0. |
1948 | */ |
1949 | if (!delay) { |
1950 | __queue_work(cpu, wq, work: &dwork->work); |
1951 | return; |
1952 | } |
1953 | |
1954 | dwork->wq = wq; |
1955 | dwork->cpu = cpu; |
1956 | timer->expires = jiffies + delay; |
1957 | |
1958 | if (unlikely(cpu != WORK_CPU_UNBOUND)) |
1959 | add_timer_on(timer, cpu); |
1960 | else |
1961 | add_timer(timer); |
1962 | } |
1963 | |
1964 | /** |
1965 | * queue_delayed_work_on - queue work on specific CPU after delay |
1966 | * @cpu: CPU number to execute work on |
1967 | * @wq: workqueue to use |
1968 | * @dwork: work to queue |
1969 | * @delay: number of jiffies to wait before queueing |
1970 | * |
1971 | * Return: %false if @work was already on a queue, %true otherwise. If |
1972 | * @delay is zero and @dwork is idle, it will be scheduled for immediate |
1973 | * execution. |
1974 | */ |
1975 | bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1976 | struct delayed_work *dwork, unsigned long delay) |
1977 | { |
1978 | struct work_struct *work = &dwork->work; |
1979 | bool ret = false; |
1980 | unsigned long flags; |
1981 | |
1982 | /* read the comment in __queue_work() */ |
1983 | local_irq_save(flags); |
1984 | |
1985 | if (!test_and_set_bit(nr: WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1986 | __queue_delayed_work(cpu, wq, dwork, delay); |
1987 | ret = true; |
1988 | } |
1989 | |
1990 | local_irq_restore(flags); |
1991 | return ret; |
1992 | } |
1993 | EXPORT_SYMBOL(queue_delayed_work_on); |
1994 | |
1995 | /** |
1996 | * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU |
1997 | * @cpu: CPU number to execute work on |
1998 | * @wq: workqueue to use |
1999 | * @dwork: work to queue |
2000 | * @delay: number of jiffies to wait before queueing |
2001 | * |
2002 | * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, |
2003 | * modify @dwork's timer so that it expires after @delay. If @delay is |
2004 | * zero, @work is guaranteed to be scheduled immediately regardless of its |
2005 | * current state. |
2006 | * |
2007 | * Return: %false if @dwork was idle and queued, %true if @dwork was |
2008 | * pending and its timer was modified. |
2009 | * |
2010 | * This function is safe to call from any context including IRQ handler. |
2011 | * See try_to_grab_pending() for details. |
2012 | */ |
2013 | bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, |
2014 | struct delayed_work *dwork, unsigned long delay) |
2015 | { |
2016 | unsigned long flags; |
2017 | int ret; |
2018 | |
2019 | do { |
2020 | ret = try_to_grab_pending(work: &dwork->work, is_dwork: true, flags: &flags); |
2021 | } while (unlikely(ret == -EAGAIN)); |
2022 | |
2023 | if (likely(ret >= 0)) { |
2024 | __queue_delayed_work(cpu, wq, dwork, delay); |
2025 | local_irq_restore(flags); |
2026 | } |
2027 | |
2028 | /* -ENOENT from try_to_grab_pending() becomes %true */ |
2029 | return ret; |
2030 | } |
2031 | EXPORT_SYMBOL_GPL(mod_delayed_work_on); |
2032 | |
2033 | static void rcu_work_rcufn(struct rcu_head *rcu) |
2034 | { |
2035 | struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu); |
2036 | |
2037 | /* read the comment in __queue_work() */ |
2038 | local_irq_disable(); |
2039 | __queue_work(cpu: WORK_CPU_UNBOUND, wq: rwork->wq, work: &rwork->work); |
2040 | local_irq_enable(); |
2041 | } |
2042 | |
2043 | /** |
2044 | * queue_rcu_work - queue work after a RCU grace period |
2045 | * @wq: workqueue to use |
2046 | * @rwork: work to queue |
2047 | * |
2048 | * Return: %false if @rwork was already pending, %true otherwise. Note |
2049 | * that a full RCU grace period is guaranteed only after a %true return. |
2050 | * While @rwork is guaranteed to be executed after a %false return, the |
2051 | * execution may happen before a full RCU grace period has passed. |
2052 | */ |
2053 | bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork) |
2054 | { |
2055 | struct work_struct *work = &rwork->work; |
2056 | |
2057 | if (!test_and_set_bit(nr: WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
2058 | rwork->wq = wq; |
2059 | call_rcu_hurry(head: &rwork->rcu, func: rcu_work_rcufn); |
2060 | return true; |
2061 | } |
2062 | |
2063 | return false; |
2064 | } |
2065 | EXPORT_SYMBOL(queue_rcu_work); |
2066 | |
2067 | static struct worker *alloc_worker(int node) |
2068 | { |
2069 | struct worker *worker; |
2070 | |
2071 | worker = kzalloc_node(size: sizeof(*worker), GFP_KERNEL, node); |
2072 | if (worker) { |
2073 | INIT_LIST_HEAD(list: &worker->entry); |
2074 | INIT_LIST_HEAD(list: &worker->scheduled); |
2075 | INIT_LIST_HEAD(list: &worker->node); |
2076 | /* on creation a worker is in !idle && prep state */ |
2077 | worker->flags = WORKER_PREP; |
2078 | } |
2079 | return worker; |
2080 | } |
2081 | |
2082 | static cpumask_t *pool_allowed_cpus(struct worker_pool *pool) |
2083 | { |
2084 | if (pool->cpu < 0 && pool->attrs->affn_strict) |
2085 | return pool->attrs->__pod_cpumask; |
2086 | else |
2087 | return pool->attrs->cpumask; |
2088 | } |
2089 | |
2090 | /** |
2091 | * worker_attach_to_pool() - attach a worker to a pool |
2092 | * @worker: worker to be attached |
2093 | * @pool: the target pool |
2094 | * |
2095 | * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and |
2096 | * cpu-binding of @worker are kept coordinated with the pool across |
2097 | * cpu-[un]hotplugs. |
2098 | */ |
2099 | static void worker_attach_to_pool(struct worker *worker, |
2100 | struct worker_pool *pool) |
2101 | { |
2102 | mutex_lock(&wq_pool_attach_mutex); |
2103 | |
2104 | /* |
2105 | * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains |
2106 | * stable across this function. See the comments above the flag |
2107 | * definition for details. |
2108 | */ |
2109 | if (pool->flags & POOL_DISASSOCIATED) |
2110 | worker->flags |= WORKER_UNBOUND; |
2111 | else |
2112 | kthread_set_per_cpu(k: worker->task, cpu: pool->cpu); |
2113 | |
2114 | if (worker->rescue_wq) |
2115 | set_cpus_allowed_ptr(p: worker->task, new_mask: pool_allowed_cpus(pool)); |
2116 | |
2117 | list_add_tail(new: &worker->node, head: &pool->workers); |
2118 | worker->pool = pool; |
2119 | |
2120 | mutex_unlock(lock: &wq_pool_attach_mutex); |
2121 | } |
2122 | |
2123 | /** |
2124 | * worker_detach_from_pool() - detach a worker from its pool |
2125 | * @worker: worker which is attached to its pool |
2126 | * |
2127 | * Undo the attaching which had been done in worker_attach_to_pool(). The |
2128 | * caller worker shouldn't access to the pool after detached except it has |
2129 | * other reference to the pool. |
2130 | */ |
2131 | static void worker_detach_from_pool(struct worker *worker) |
2132 | { |
2133 | struct worker_pool *pool = worker->pool; |
2134 | struct completion *detach_completion = NULL; |
2135 | |
2136 | mutex_lock(&wq_pool_attach_mutex); |
2137 | |
2138 | kthread_set_per_cpu(k: worker->task, cpu: -1); |
2139 | list_del(entry: &worker->node); |
2140 | worker->pool = NULL; |
2141 | |
2142 | if (list_empty(head: &pool->workers) && list_empty(head: &pool->dying_workers)) |
2143 | detach_completion = pool->detach_completion; |
2144 | mutex_unlock(lock: &wq_pool_attach_mutex); |
2145 | |
2146 | /* clear leftover flags without pool->lock after it is detached */ |
2147 | worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND); |
2148 | |
2149 | if (detach_completion) |
2150 | complete(detach_completion); |
2151 | } |
2152 | |
2153 | /** |
2154 | * create_worker - create a new workqueue worker |
2155 | * @pool: pool the new worker will belong to |
2156 | * |
2157 | * Create and start a new worker which is attached to @pool. |
2158 | * |
2159 | * CONTEXT: |
2160 | * Might sleep. Does GFP_KERNEL allocations. |
2161 | * |
2162 | * Return: |
2163 | * Pointer to the newly created worker. |
2164 | */ |
2165 | static struct worker *create_worker(struct worker_pool *pool) |
2166 | { |
2167 | struct worker *worker; |
2168 | int id; |
2169 | char id_buf[23]; |
2170 | |
2171 | /* ID is needed to determine kthread name */ |
2172 | id = ida_alloc(ida: &pool->worker_ida, GFP_KERNEL); |
2173 | if (id < 0) { |
2174 | pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n" , |
2175 | ERR_PTR(id)); |
2176 | return NULL; |
2177 | } |
2178 | |
2179 | worker = alloc_worker(node: pool->node); |
2180 | if (!worker) { |
2181 | pr_err_once("workqueue: Failed to allocate a worker\n" ); |
2182 | goto fail; |
2183 | } |
2184 | |
2185 | worker->id = id; |
2186 | |
2187 | if (pool->cpu >= 0) |
2188 | snprintf(buf: id_buf, size: sizeof(id_buf), fmt: "%d:%d%s" , pool->cpu, id, |
2189 | pool->attrs->nice < 0 ? "H" : "" ); |
2190 | else |
2191 | snprintf(buf: id_buf, size: sizeof(id_buf), fmt: "u%d:%d" , pool->id, id); |
2192 | |
2193 | worker->task = kthread_create_on_node(threadfn: worker_thread, data: worker, node: pool->node, |
2194 | namefmt: "kworker/%s" , id_buf); |
2195 | if (IS_ERR(ptr: worker->task)) { |
2196 | if (PTR_ERR(ptr: worker->task) == -EINTR) { |
2197 | pr_err("workqueue: Interrupted when creating a worker thread \"kworker/%s\"\n" , |
2198 | id_buf); |
2199 | } else { |
2200 | pr_err_once("workqueue: Failed to create a worker thread: %pe" , |
2201 | worker->task); |
2202 | } |
2203 | goto fail; |
2204 | } |
2205 | |
2206 | set_user_nice(p: worker->task, nice: pool->attrs->nice); |
2207 | kthread_bind_mask(k: worker->task, mask: pool_allowed_cpus(pool)); |
2208 | |
2209 | /* successful, attach the worker to the pool */ |
2210 | worker_attach_to_pool(worker, pool); |
2211 | |
2212 | /* start the newly created worker */ |
2213 | raw_spin_lock_irq(&pool->lock); |
2214 | |
2215 | worker->pool->nr_workers++; |
2216 | worker_enter_idle(worker); |
2217 | kick_pool(pool); |
2218 | |
2219 | /* |
2220 | * @worker is waiting on a completion in kthread() and will trigger hung |
2221 | * check if not woken up soon. As kick_pool() might not have waken it |
2222 | * up, wake it up explicitly once more. |
2223 | */ |
2224 | wake_up_process(tsk: worker->task); |
2225 | |
2226 | raw_spin_unlock_irq(&pool->lock); |
2227 | |
2228 | return worker; |
2229 | |
2230 | fail: |
2231 | ida_free(&pool->worker_ida, id); |
2232 | kfree(objp: worker); |
2233 | return NULL; |
2234 | } |
2235 | |
2236 | static void unbind_worker(struct worker *worker) |
2237 | { |
2238 | lockdep_assert_held(&wq_pool_attach_mutex); |
2239 | |
2240 | kthread_set_per_cpu(k: worker->task, cpu: -1); |
2241 | if (cpumask_intersects(src1p: wq_unbound_cpumask, cpu_active_mask)) |
2242 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0); |
2243 | else |
2244 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); |
2245 | } |
2246 | |
2247 | static void wake_dying_workers(struct list_head *cull_list) |
2248 | { |
2249 | struct worker *worker, *tmp; |
2250 | |
2251 | list_for_each_entry_safe(worker, tmp, cull_list, entry) { |
2252 | list_del_init(entry: &worker->entry); |
2253 | unbind_worker(worker); |
2254 | /* |
2255 | * If the worker was somehow already running, then it had to be |
2256 | * in pool->idle_list when set_worker_dying() happened or we |
2257 | * wouldn't have gotten here. |
2258 | * |
2259 | * Thus, the worker must either have observed the WORKER_DIE |
2260 | * flag, or have set its state to TASK_IDLE. Either way, the |
2261 | * below will be observed by the worker and is safe to do |
2262 | * outside of pool->lock. |
2263 | */ |
2264 | wake_up_process(tsk: worker->task); |
2265 | } |
2266 | } |
2267 | |
2268 | /** |
2269 | * set_worker_dying - Tag a worker for destruction |
2270 | * @worker: worker to be destroyed |
2271 | * @list: transfer worker away from its pool->idle_list and into list |
2272 | * |
2273 | * Tag @worker for destruction and adjust @pool stats accordingly. The worker |
2274 | * should be idle. |
2275 | * |
2276 | * CONTEXT: |
2277 | * raw_spin_lock_irq(pool->lock). |
2278 | */ |
2279 | static void set_worker_dying(struct worker *worker, struct list_head *list) |
2280 | { |
2281 | struct worker_pool *pool = worker->pool; |
2282 | |
2283 | lockdep_assert_held(&pool->lock); |
2284 | lockdep_assert_held(&wq_pool_attach_mutex); |
2285 | |
2286 | /* sanity check frenzy */ |
2287 | if (WARN_ON(worker->current_work) || |
2288 | WARN_ON(!list_empty(&worker->scheduled)) || |
2289 | WARN_ON(!(worker->flags & WORKER_IDLE))) |
2290 | return; |
2291 | |
2292 | pool->nr_workers--; |
2293 | pool->nr_idle--; |
2294 | |
2295 | worker->flags |= WORKER_DIE; |
2296 | |
2297 | list_move(list: &worker->entry, head: list); |
2298 | list_move(list: &worker->node, head: &pool->dying_workers); |
2299 | } |
2300 | |
2301 | /** |
2302 | * idle_worker_timeout - check if some idle workers can now be deleted. |
2303 | * @t: The pool's idle_timer that just expired |
2304 | * |
2305 | * The timer is armed in worker_enter_idle(). Note that it isn't disarmed in |
2306 | * worker_leave_idle(), as a worker flicking between idle and active while its |
2307 | * pool is at the too_many_workers() tipping point would cause too much timer |
2308 | * housekeeping overhead. Since IDLE_WORKER_TIMEOUT is long enough, we just let |
2309 | * it expire and re-evaluate things from there. |
2310 | */ |
2311 | static void idle_worker_timeout(struct timer_list *t) |
2312 | { |
2313 | struct worker_pool *pool = from_timer(pool, t, idle_timer); |
2314 | bool do_cull = false; |
2315 | |
2316 | if (work_pending(&pool->idle_cull_work)) |
2317 | return; |
2318 | |
2319 | raw_spin_lock_irq(&pool->lock); |
2320 | |
2321 | if (too_many_workers(pool)) { |
2322 | struct worker *worker; |
2323 | unsigned long expires; |
2324 | |
2325 | /* idle_list is kept in LIFO order, check the last one */ |
2326 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
2327 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
2328 | do_cull = !time_before(jiffies, expires); |
2329 | |
2330 | if (!do_cull) |
2331 | mod_timer(timer: &pool->idle_timer, expires); |
2332 | } |
2333 | raw_spin_unlock_irq(&pool->lock); |
2334 | |
2335 | if (do_cull) |
2336 | queue_work(wq: system_unbound_wq, work: &pool->idle_cull_work); |
2337 | } |
2338 | |
2339 | /** |
2340 | * idle_cull_fn - cull workers that have been idle for too long. |
2341 | * @work: the pool's work for handling these idle workers |
2342 | * |
2343 | * This goes through a pool's idle workers and gets rid of those that have been |
2344 | * idle for at least IDLE_WORKER_TIMEOUT seconds. |
2345 | * |
2346 | * We don't want to disturb isolated CPUs because of a pcpu kworker being |
2347 | * culled, so this also resets worker affinity. This requires a sleepable |
2348 | * context, hence the split between timer callback and work item. |
2349 | */ |
2350 | static void idle_cull_fn(struct work_struct *work) |
2351 | { |
2352 | struct worker_pool *pool = container_of(work, struct worker_pool, idle_cull_work); |
2353 | LIST_HEAD(cull_list); |
2354 | |
2355 | /* |
2356 | * Grabbing wq_pool_attach_mutex here ensures an already-running worker |
2357 | * cannot proceed beyong worker_detach_from_pool() in its self-destruct |
2358 | * path. This is required as a previously-preempted worker could run after |
2359 | * set_worker_dying() has happened but before wake_dying_workers() did. |
2360 | */ |
2361 | mutex_lock(&wq_pool_attach_mutex); |
2362 | raw_spin_lock_irq(&pool->lock); |
2363 | |
2364 | while (too_many_workers(pool)) { |
2365 | struct worker *worker; |
2366 | unsigned long expires; |
2367 | |
2368 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
2369 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
2370 | |
2371 | if (time_before(jiffies, expires)) { |
2372 | mod_timer(timer: &pool->idle_timer, expires); |
2373 | break; |
2374 | } |
2375 | |
2376 | set_worker_dying(worker, list: &cull_list); |
2377 | } |
2378 | |
2379 | raw_spin_unlock_irq(&pool->lock); |
2380 | wake_dying_workers(cull_list: &cull_list); |
2381 | mutex_unlock(lock: &wq_pool_attach_mutex); |
2382 | } |
2383 | |
2384 | static void send_mayday(struct work_struct *work) |
2385 | { |
2386 | struct pool_workqueue *pwq = get_work_pwq(work); |
2387 | struct workqueue_struct *wq = pwq->wq; |
2388 | |
2389 | lockdep_assert_held(&wq_mayday_lock); |
2390 | |
2391 | if (!wq->rescuer) |
2392 | return; |
2393 | |
2394 | /* mayday mayday mayday */ |
2395 | if (list_empty(head: &pwq->mayday_node)) { |
2396 | /* |
2397 | * If @pwq is for an unbound wq, its base ref may be put at |
2398 | * any time due to an attribute change. Pin @pwq until the |
2399 | * rescuer is done with it. |
2400 | */ |
2401 | get_pwq(pwq); |
2402 | list_add_tail(new: &pwq->mayday_node, head: &wq->maydays); |
2403 | wake_up_process(tsk: wq->rescuer->task); |
2404 | pwq->stats[PWQ_STAT_MAYDAY]++; |
2405 | } |
2406 | } |
2407 | |
2408 | static void pool_mayday_timeout(struct timer_list *t) |
2409 | { |
2410 | struct worker_pool *pool = from_timer(pool, t, mayday_timer); |
2411 | struct work_struct *work; |
2412 | |
2413 | raw_spin_lock_irq(&pool->lock); |
2414 | raw_spin_lock(&wq_mayday_lock); /* for wq->maydays */ |
2415 | |
2416 | if (need_to_create_worker(pool)) { |
2417 | /* |
2418 | * We've been trying to create a new worker but |
2419 | * haven't been successful. We might be hitting an |
2420 | * allocation deadlock. Send distress signals to |
2421 | * rescuers. |
2422 | */ |
2423 | list_for_each_entry(work, &pool->worklist, entry) |
2424 | send_mayday(work); |
2425 | } |
2426 | |
2427 | raw_spin_unlock(&wq_mayday_lock); |
2428 | raw_spin_unlock_irq(&pool->lock); |
2429 | |
2430 | mod_timer(timer: &pool->mayday_timer, expires: jiffies + MAYDAY_INTERVAL); |
2431 | } |
2432 | |
2433 | /** |
2434 | * maybe_create_worker - create a new worker if necessary |
2435 | * @pool: pool to create a new worker for |
2436 | * |
2437 | * Create a new worker for @pool if necessary. @pool is guaranteed to |
2438 | * have at least one idle worker on return from this function. If |
2439 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is |
2440 | * sent to all rescuers with works scheduled on @pool to resolve |
2441 | * possible allocation deadlock. |
2442 | * |
2443 | * On return, need_to_create_worker() is guaranteed to be %false and |
2444 | * may_start_working() %true. |
2445 | * |
2446 | * LOCKING: |
2447 | * raw_spin_lock_irq(pool->lock) which may be released and regrabbed |
2448 | * multiple times. Does GFP_KERNEL allocations. Called only from |
2449 | * manager. |
2450 | */ |
2451 | static void maybe_create_worker(struct worker_pool *pool) |
2452 | __releases(&pool->lock) |
2453 | __acquires(&pool->lock) |
2454 | { |
2455 | restart: |
2456 | raw_spin_unlock_irq(&pool->lock); |
2457 | |
2458 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
2459 | mod_timer(timer: &pool->mayday_timer, expires: jiffies + MAYDAY_INITIAL_TIMEOUT); |
2460 | |
2461 | while (true) { |
2462 | if (create_worker(pool) || !need_to_create_worker(pool)) |
2463 | break; |
2464 | |
2465 | schedule_timeout_interruptible(timeout: CREATE_COOLDOWN); |
2466 | |
2467 | if (!need_to_create_worker(pool)) |
2468 | break; |
2469 | } |
2470 | |
2471 | del_timer_sync(timer: &pool->mayday_timer); |
2472 | raw_spin_lock_irq(&pool->lock); |
2473 | /* |
2474 | * This is necessary even after a new worker was just successfully |
2475 | * created as @pool->lock was dropped and the new worker might have |
2476 | * already become busy. |
2477 | */ |
2478 | if (need_to_create_worker(pool)) |
2479 | goto restart; |
2480 | } |
2481 | |
2482 | /** |
2483 | * manage_workers - manage worker pool |
2484 | * @worker: self |
2485 | * |
2486 | * Assume the manager role and manage the worker pool @worker belongs |
2487 | * to. At any given time, there can be only zero or one manager per |
2488 | * pool. The exclusion is handled automatically by this function. |
2489 | * |
2490 | * The caller can safely start processing works on false return. On |
2491 | * true return, it's guaranteed that need_to_create_worker() is false |
2492 | * and may_start_working() is true. |
2493 | * |
2494 | * CONTEXT: |
2495 | * raw_spin_lock_irq(pool->lock) which may be released and regrabbed |
2496 | * multiple times. Does GFP_KERNEL allocations. |
2497 | * |
2498 | * Return: |
2499 | * %false if the pool doesn't need management and the caller can safely |
2500 | * start processing works, %true if management function was performed and |
2501 | * the conditions that the caller verified before calling the function may |
2502 | * no longer be true. |
2503 | */ |
2504 | static bool manage_workers(struct worker *worker) |
2505 | { |
2506 | struct worker_pool *pool = worker->pool; |
2507 | |
2508 | if (pool->flags & POOL_MANAGER_ACTIVE) |
2509 | return false; |
2510 | |
2511 | pool->flags |= POOL_MANAGER_ACTIVE; |
2512 | pool->manager = worker; |
2513 | |
2514 | maybe_create_worker(pool); |
2515 | |
2516 | pool->manager = NULL; |
2517 | pool->flags &= ~POOL_MANAGER_ACTIVE; |
2518 | rcuwait_wake_up(w: &manager_wait); |
2519 | return true; |
2520 | } |
2521 | |
2522 | /** |
2523 | * process_one_work - process single work |
2524 | * @worker: self |
2525 | * @work: work to process |
2526 | * |
2527 | * Process @work. This function contains all the logics necessary to |
2528 | * process a single work including synchronization against and |
2529 | * interaction with other workers on the same cpu, queueing and |
2530 | * flushing. As long as context requirement is met, any worker can |
2531 | * call this function to process a work. |
2532 | * |
2533 | * CONTEXT: |
2534 | * raw_spin_lock_irq(pool->lock) which is released and regrabbed. |
2535 | */ |
2536 | static void process_one_work(struct worker *worker, struct work_struct *work) |
2537 | __releases(&pool->lock) |
2538 | __acquires(&pool->lock) |
2539 | { |
2540 | struct pool_workqueue *pwq = get_work_pwq(work); |
2541 | struct worker_pool *pool = worker->pool; |
2542 | unsigned long work_data; |
2543 | #ifdef CONFIG_LOCKDEP |
2544 | /* |
2545 | * It is permissible to free the struct work_struct from |
2546 | * inside the function that is called from it, this we need to |
2547 | * take into account for lockdep too. To avoid bogus "held |
2548 | * lock freed" warnings as well as problems when looking into |
2549 | * work->lockdep_map, make a copy and use that here. |
2550 | */ |
2551 | struct lockdep_map lockdep_map; |
2552 | |
2553 | lockdep_copy_map(to: &lockdep_map, from: &work->lockdep_map); |
2554 | #endif |
2555 | /* ensure we're on the correct CPU */ |
2556 | WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && |
2557 | raw_smp_processor_id() != pool->cpu); |
2558 | |
2559 | /* claim and dequeue */ |
2560 | debug_work_deactivate(work); |
2561 | hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); |
2562 | worker->current_work = work; |
2563 | worker->current_func = work->func; |
2564 | worker->current_pwq = pwq; |
2565 | worker->current_at = worker->task->se.sum_exec_runtime; |
2566 | work_data = *work_data_bits(work); |
2567 | worker->current_color = get_work_color(work_data); |
2568 | |
2569 | /* |
2570 | * Record wq name for cmdline and debug reporting, may get |
2571 | * overridden through set_worker_desc(). |
2572 | */ |
2573 | strscpy(p: worker->desc, q: pwq->wq->name, size: WORKER_DESC_LEN); |
2574 | |
2575 | list_del_init(entry: &work->entry); |
2576 | |
2577 | /* |
2578 | * CPU intensive works don't participate in concurrency management. |
2579 | * They're the scheduler's responsibility. This takes @worker out |
2580 | * of concurrency management and the next code block will chain |
2581 | * execution of the pending work items. |
2582 | */ |
2583 | if (unlikely(pwq->wq->flags & WQ_CPU_INTENSIVE)) |
2584 | worker_set_flags(worker, flags: WORKER_CPU_INTENSIVE); |
2585 | |
2586 | /* |
2587 | * Kick @pool if necessary. It's always noop for per-cpu worker pools |
2588 | * since nr_running would always be >= 1 at this point. This is used to |
2589 | * chain execution of the pending work items for WORKER_NOT_RUNNING |
2590 | * workers such as the UNBOUND and CPU_INTENSIVE ones. |
2591 | */ |
2592 | kick_pool(pool); |
2593 | |
2594 | /* |
2595 | * Record the last pool and clear PENDING which should be the last |
2596 | * update to @work. Also, do this inside @pool->lock so that |
2597 | * PENDING and queued state changes happen together while IRQ is |
2598 | * disabled. |
2599 | */ |
2600 | set_work_pool_and_clear_pending(work, pool_id: pool->id); |
2601 | |
2602 | pwq->stats[PWQ_STAT_STARTED]++; |
2603 | raw_spin_unlock_irq(&pool->lock); |
2604 | |
2605 | lock_map_acquire(&pwq->wq->lockdep_map); |
2606 | lock_map_acquire(&lockdep_map); |
2607 | /* |
2608 | * Strictly speaking we should mark the invariant state without holding |
2609 | * any locks, that is, before these two lock_map_acquire()'s. |
2610 | * |
2611 | * However, that would result in: |
2612 | * |
2613 | * A(W1) |
2614 | * WFC(C) |
2615 | * A(W1) |
2616 | * C(C) |
2617 | * |
2618 | * Which would create W1->C->W1 dependencies, even though there is no |
2619 | * actual deadlock possible. There are two solutions, using a |
2620 | * read-recursive acquire on the work(queue) 'locks', but this will then |
2621 | * hit the lockdep limitation on recursive locks, or simply discard |
2622 | * these locks. |
2623 | * |
2624 | * AFAICT there is no possible deadlock scenario between the |
2625 | * flush_work() and complete() primitives (except for single-threaded |
2626 | * workqueues), so hiding them isn't a problem. |
2627 | */ |
2628 | lockdep_invariant_state(force: true); |
2629 | trace_workqueue_execute_start(work); |
2630 | worker->current_func(work); |
2631 | /* |
2632 | * While we must be careful to not use "work" after this, the trace |
2633 | * point will only record its address. |
2634 | */ |
2635 | trace_workqueue_execute_end(work, function: worker->current_func); |
2636 | pwq->stats[PWQ_STAT_COMPLETED]++; |
2637 | lock_map_release(&lockdep_map); |
2638 | lock_map_release(&pwq->wq->lockdep_map); |
2639 | |
2640 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
2641 | pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" |
2642 | " last function: %ps\n" , |
2643 | current->comm, preempt_count(), task_pid_nr(current), |
2644 | worker->current_func); |
2645 | debug_show_held_locks(current); |
2646 | dump_stack(); |
2647 | } |
2648 | |
2649 | /* |
2650 | * The following prevents a kworker from hogging CPU on !PREEMPTION |
2651 | * kernels, where a requeueing work item waiting for something to |
2652 | * happen could deadlock with stop_machine as such work item could |
2653 | * indefinitely requeue itself while all other CPUs are trapped in |
2654 | * stop_machine. At the same time, report a quiescent RCU state so |
2655 | * the same condition doesn't freeze RCU. |
2656 | */ |
2657 | cond_resched(); |
2658 | |
2659 | raw_spin_lock_irq(&pool->lock); |
2660 | |
2661 | /* |
2662 | * In addition to %WQ_CPU_INTENSIVE, @worker may also have been marked |
2663 | * CPU intensive by wq_worker_tick() if @work hogged CPU longer than |
2664 | * wq_cpu_intensive_thresh_us. Clear it. |
2665 | */ |
2666 | worker_clr_flags(worker, flags: WORKER_CPU_INTENSIVE); |
2667 | |
2668 | /* tag the worker for identification in schedule() */ |
2669 | worker->last_func = worker->current_func; |
2670 | |
2671 | /* we're done with it, release */ |
2672 | hash_del(node: &worker->hentry); |
2673 | worker->current_work = NULL; |
2674 | worker->current_func = NULL; |
2675 | worker->current_pwq = NULL; |
2676 | worker->current_color = INT_MAX; |
2677 | pwq_dec_nr_in_flight(pwq, work_data); |
2678 | } |
2679 | |
2680 | /** |
2681 | * process_scheduled_works - process scheduled works |
2682 | * @worker: self |
2683 | * |
2684 | * Process all scheduled works. Please note that the scheduled list |
2685 | * may change while processing a work, so this function repeatedly |
2686 | * fetches a work from the top and executes it. |
2687 | * |
2688 | * CONTEXT: |
2689 | * raw_spin_lock_irq(pool->lock) which may be released and regrabbed |
2690 | * multiple times. |
2691 | */ |
2692 | static void process_scheduled_works(struct worker *worker) |
2693 | { |
2694 | struct work_struct *work; |
2695 | bool first = true; |
2696 | |
2697 | while ((work = list_first_entry_or_null(&worker->scheduled, |
2698 | struct work_struct, entry))) { |
2699 | if (first) { |
2700 | worker->pool->watchdog_ts = jiffies; |
2701 | first = false; |
2702 | } |
2703 | process_one_work(worker, work); |
2704 | } |
2705 | } |
2706 | |
2707 | static void set_pf_worker(bool val) |
2708 | { |
2709 | mutex_lock(&wq_pool_attach_mutex); |
2710 | if (val) |
2711 | current->flags |= PF_WQ_WORKER; |
2712 | else |
2713 | current->flags &= ~PF_WQ_WORKER; |
2714 | mutex_unlock(lock: &wq_pool_attach_mutex); |
2715 | } |
2716 | |
2717 | /** |
2718 | * worker_thread - the worker thread function |
2719 | * @__worker: self |
2720 | * |
2721 | * The worker thread function. All workers belong to a worker_pool - |
2722 | * either a per-cpu one or dynamic unbound one. These workers process all |
2723 | * work items regardless of their specific target workqueue. The only |
2724 | * exception is work items which belong to workqueues with a rescuer which |
2725 | * will be explained in rescuer_thread(). |
2726 | * |
2727 | * Return: 0 |
2728 | */ |
2729 | static int worker_thread(void *__worker) |
2730 | { |
2731 | struct worker *worker = __worker; |
2732 | struct worker_pool *pool = worker->pool; |
2733 | |
2734 | /* tell the scheduler that this is a workqueue worker */ |
2735 | set_pf_worker(true); |
2736 | woke_up: |
2737 | raw_spin_lock_irq(&pool->lock); |
2738 | |
2739 | /* am I supposed to die? */ |
2740 | if (unlikely(worker->flags & WORKER_DIE)) { |
2741 | raw_spin_unlock_irq(&pool->lock); |
2742 | set_pf_worker(false); |
2743 | |
2744 | set_task_comm(tsk: worker->task, from: "kworker/dying" ); |
2745 | ida_free(&pool->worker_ida, id: worker->id); |
2746 | worker_detach_from_pool(worker); |
2747 | WARN_ON_ONCE(!list_empty(&worker->entry)); |
2748 | kfree(objp: worker); |
2749 | return 0; |
2750 | } |
2751 | |
2752 | worker_leave_idle(worker); |
2753 | recheck: |
2754 | /* no more worker necessary? */ |
2755 | if (!need_more_worker(pool)) |
2756 | goto sleep; |
2757 | |
2758 | /* do we need to manage? */ |
2759 | if (unlikely(!may_start_working(pool)) && manage_workers(worker)) |
2760 | goto recheck; |
2761 | |
2762 | /* |
2763 | * ->scheduled list can only be filled while a worker is |
2764 | * preparing to process a work or actually processing it. |
2765 | * Make sure nobody diddled with it while I was sleeping. |
2766 | */ |
2767 | WARN_ON_ONCE(!list_empty(&worker->scheduled)); |
2768 | |
2769 | /* |
2770 | * Finish PREP stage. We're guaranteed to have at least one idle |
2771 | * worker or that someone else has already assumed the manager |
2772 | * role. This is where @worker starts participating in concurrency |
2773 | * management if applicable and concurrency management is restored |
2774 | * after being rebound. See rebind_workers() for details. |
2775 | */ |
2776 | worker_clr_flags(worker, flags: WORKER_PREP | WORKER_REBOUND); |
2777 | |
2778 | do { |
2779 | struct work_struct *work = |
2780 | list_first_entry(&pool->worklist, |
2781 | struct work_struct, entry); |
2782 | |
2783 | if (assign_work(work, worker, NULL)) |
2784 | process_scheduled_works(worker); |
2785 | } while (keep_working(pool)); |
2786 | |
2787 | worker_set_flags(worker, flags: WORKER_PREP); |
2788 | sleep: |
2789 | /* |
2790 | * pool->lock is held and there's no work to process and no need to |
2791 | * manage, sleep. Workers are woken up only while holding |
2792 | * pool->lock or from local cpu, so setting the current state |
2793 | * before releasing pool->lock is enough to prevent losing any |
2794 | * event. |
2795 | */ |
2796 | worker_enter_idle(worker); |
2797 | __set_current_state(TASK_IDLE); |
2798 | raw_spin_unlock_irq(&pool->lock); |
2799 | schedule(); |
2800 | goto woke_up; |
2801 | } |
2802 | |
2803 | /** |
2804 | * rescuer_thread - the rescuer thread function |
2805 | * @__rescuer: self |
2806 | * |
2807 | * Workqueue rescuer thread function. There's one rescuer for each |
2808 | * workqueue which has WQ_MEM_RECLAIM set. |
2809 | * |
2810 | * Regular work processing on a pool may block trying to create a new |
2811 | * worker which uses GFP_KERNEL allocation which has slight chance of |
2812 | * developing into deadlock if some works currently on the same queue |
2813 | * need to be processed to satisfy the GFP_KERNEL allocation. This is |
2814 | * the problem rescuer solves. |
2815 | * |
2816 | * When such condition is possible, the pool summons rescuers of all |
2817 | * workqueues which have works queued on the pool and let them process |
2818 | * those works so that forward progress can be guaranteed. |
2819 | * |
2820 | * This should happen rarely. |
2821 | * |
2822 | * Return: 0 |
2823 | */ |
2824 | static int rescuer_thread(void *__rescuer) |
2825 | { |
2826 | struct worker *rescuer = __rescuer; |
2827 | struct workqueue_struct *wq = rescuer->rescue_wq; |
2828 | bool should_stop; |
2829 | |
2830 | set_user_nice(current, nice: RESCUER_NICE_LEVEL); |
2831 | |
2832 | /* |
2833 | * Mark rescuer as worker too. As WORKER_PREP is never cleared, it |
2834 | * doesn't participate in concurrency management. |
2835 | */ |
2836 | set_pf_worker(true); |
2837 | repeat: |
2838 | set_current_state(TASK_IDLE); |
2839 | |
2840 | /* |
2841 | * By the time the rescuer is requested to stop, the workqueue |
2842 | * shouldn't have any work pending, but @wq->maydays may still have |
2843 | * pwq(s) queued. This can happen by non-rescuer workers consuming |
2844 | * all the work items before the rescuer got to them. Go through |
2845 | * @wq->maydays processing before acting on should_stop so that the |
2846 | * list is always empty on exit. |
2847 | */ |
2848 | should_stop = kthread_should_stop(); |
2849 | |
2850 | /* see whether any pwq is asking for help */ |
2851 | raw_spin_lock_irq(&wq_mayday_lock); |
2852 | |
2853 | while (!list_empty(head: &wq->maydays)) { |
2854 | struct pool_workqueue *pwq = list_first_entry(&wq->maydays, |
2855 | struct pool_workqueue, mayday_node); |
2856 | struct worker_pool *pool = pwq->pool; |
2857 | struct work_struct *work, *n; |
2858 | |
2859 | __set_current_state(TASK_RUNNING); |
2860 | list_del_init(entry: &pwq->mayday_node); |
2861 | |
2862 | raw_spin_unlock_irq(&wq_mayday_lock); |
2863 | |
2864 | worker_attach_to_pool(worker: rescuer, pool); |
2865 | |
2866 | raw_spin_lock_irq(&pool->lock); |
2867 | |
2868 | /* |
2869 | * Slurp in all works issued via this workqueue and |
2870 | * process'em. |
2871 | */ |
2872 | WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); |
2873 | list_for_each_entry_safe(work, n, &pool->worklist, entry) { |
2874 | if (get_work_pwq(work) == pwq && |
2875 | assign_work(work, worker: rescuer, nextp: &n)) |
2876 | pwq->stats[PWQ_STAT_RESCUED]++; |
2877 | } |
2878 | |
2879 | if (!list_empty(head: &rescuer->scheduled)) { |
2880 | process_scheduled_works(worker: rescuer); |
2881 | |
2882 | /* |
2883 | * The above execution of rescued work items could |
2884 | * have created more to rescue through |
2885 | * pwq_activate_first_inactive() or chained |
2886 | * queueing. Let's put @pwq back on mayday list so |
2887 | * that such back-to-back work items, which may be |
2888 | * being used to relieve memory pressure, don't |
2889 | * incur MAYDAY_INTERVAL delay inbetween. |
2890 | */ |
2891 | if (pwq->nr_active && need_to_create_worker(pool)) { |
2892 | raw_spin_lock(&wq_mayday_lock); |
2893 | /* |
2894 | * Queue iff we aren't racing destruction |
2895 | * and somebody else hasn't queued it already. |
2896 | */ |
2897 | if (wq->rescuer && list_empty(head: &pwq->mayday_node)) { |
2898 | get_pwq(pwq); |
2899 | list_add_tail(new: &pwq->mayday_node, head: &wq->maydays); |
2900 | } |
2901 | raw_spin_unlock(&wq_mayday_lock); |
2902 | } |
2903 | } |
2904 | |
2905 | /* |
2906 | * Put the reference grabbed by send_mayday(). @pool won't |
2907 | * go away while we're still attached to it. |
2908 | */ |
2909 | put_pwq(pwq); |
2910 | |
2911 | /* |
2912 | * Leave this pool. Notify regular workers; otherwise, we end up |
2913 | * with 0 concurrency and stalling the execution. |
2914 | */ |
2915 | kick_pool(pool); |
2916 | |
2917 | raw_spin_unlock_irq(&pool->lock); |
2918 | |
2919 | worker_detach_from_pool(worker: rescuer); |
2920 | |
2921 | raw_spin_lock_irq(&wq_mayday_lock); |
2922 | } |
2923 | |
2924 | raw_spin_unlock_irq(&wq_mayday_lock); |
2925 | |
2926 | if (should_stop) { |
2927 | __set_current_state(TASK_RUNNING); |
2928 | set_pf_worker(false); |
2929 | return 0; |
2930 | } |
2931 | |
2932 | /* rescuers should never participate in concurrency management */ |
2933 | WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); |
2934 | schedule(); |
2935 | goto repeat; |
2936 | } |
2937 | |
2938 | /** |
2939 | * check_flush_dependency - check for flush dependency sanity |
2940 | * @target_wq: workqueue being flushed |
2941 | * @target_work: work item being flushed (NULL for workqueue flushes) |
2942 | * |
2943 | * %current is trying to flush the whole @target_wq or @target_work on it. |
2944 | * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not |
2945 | * reclaiming memory or running on a workqueue which doesn't have |
2946 | * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to |
2947 | * a deadlock. |
2948 | */ |
2949 | static void check_flush_dependency(struct workqueue_struct *target_wq, |
2950 | struct work_struct *target_work) |
2951 | { |
2952 | work_func_t target_func = target_work ? target_work->func : NULL; |
2953 | struct worker *worker; |
2954 | |
2955 | if (target_wq->flags & WQ_MEM_RECLAIM) |
2956 | return; |
2957 | |
2958 | worker = current_wq_worker(); |
2959 | |
2960 | WARN_ONCE(current->flags & PF_MEMALLOC, |
2961 | "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps" , |
2962 | current->pid, current->comm, target_wq->name, target_func); |
2963 | WARN_ONCE(worker && ((worker->current_pwq->wq->flags & |
2964 | (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), |
2965 | "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps" , |
2966 | worker->current_pwq->wq->name, worker->current_func, |
2967 | target_wq->name, target_func); |
2968 | } |
2969 | |
2970 | struct wq_barrier { |
2971 | struct work_struct work; |
2972 | struct completion done; |
2973 | struct task_struct *task; /* purely informational */ |
2974 | }; |
2975 | |
2976 | static void wq_barrier_func(struct work_struct *work) |
2977 | { |
2978 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
2979 | complete(&barr->done); |
2980 | } |
2981 | |
2982 | /** |
2983 | * insert_wq_barrier - insert a barrier work |
2984 | * @pwq: pwq to insert barrier into |
2985 | * @barr: wq_barrier to insert |
2986 | * @target: target work to attach @barr to |
2987 | * @worker: worker currently executing @target, NULL if @target is not executing |
2988 | * |
2989 | * @barr is linked to @target such that @barr is completed only after |
2990 | * @target finishes execution. Please note that the ordering |
2991 | * guarantee is observed only with respect to @target and on the local |
2992 | * cpu. |
2993 | * |
2994 | * Currently, a queued barrier can't be canceled. This is because |
2995 | * try_to_grab_pending() can't determine whether the work to be |
2996 | * grabbed is at the head of the queue and thus can't clear LINKED |
2997 | * flag of the previous work while there must be a valid next work |
2998 | * after a work with LINKED flag set. |
2999 | * |
3000 | * Note that when @worker is non-NULL, @target may be modified |
3001 | * underneath us, so we can't reliably determine pwq from @target. |
3002 | * |
3003 | * CONTEXT: |
3004 | * raw_spin_lock_irq(pool->lock). |
3005 | */ |
3006 | static void insert_wq_barrier(struct pool_workqueue *pwq, |
3007 | struct wq_barrier *barr, |
3008 | struct work_struct *target, struct worker *worker) |
3009 | { |
3010 | unsigned int work_flags = 0; |
3011 | unsigned int work_color; |
3012 | struct list_head *head; |
3013 | |
3014 | /* |
3015 | * debugobject calls are safe here even with pool->lock locked |
3016 | * as we know for sure that this will not trigger any of the |
3017 | * checks and call back into the fixup functions where we |
3018 | * might deadlock. |
3019 | */ |
3020 | INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
3021 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
3022 | |
3023 | init_completion_map(&barr->done, &target->lockdep_map); |
3024 | |
3025 | barr->task = current; |
3026 | |
3027 | /* The barrier work item does not participate in pwq->nr_active. */ |
3028 | work_flags |= WORK_STRUCT_INACTIVE; |
3029 | |
3030 | /* |
3031 | * If @target is currently being executed, schedule the |
3032 | * barrier to the worker; otherwise, put it after @target. |
3033 | */ |
3034 | if (worker) { |
3035 | head = worker->scheduled.next; |
3036 | work_color = worker->current_color; |
3037 | } else { |
3038 | unsigned long *bits = work_data_bits(target); |
3039 | |
3040 | head = target->entry.next; |
3041 | /* there can already be other linked works, inherit and set */ |
3042 | work_flags |= *bits & WORK_STRUCT_LINKED; |
3043 | work_color = get_work_color(work_data: *bits); |
3044 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); |
3045 | } |
3046 | |
3047 | pwq->nr_in_flight[work_color]++; |
3048 | work_flags |= work_color_to_flags(color: work_color); |
3049 | |
3050 | insert_work(pwq, work: &barr->work, head, extra_flags: work_flags); |
3051 | } |
3052 | |
3053 | /** |
3054 | * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing |
3055 | * @wq: workqueue being flushed |
3056 | * @flush_color: new flush color, < 0 for no-op |
3057 | * @work_color: new work color, < 0 for no-op |
3058 | * |
3059 | * Prepare pwqs for workqueue flushing. |
3060 | * |
3061 | * If @flush_color is non-negative, flush_color on all pwqs should be |
3062 | * -1. If no pwq has in-flight commands at the specified color, all |
3063 | * pwq->flush_color's stay at -1 and %false is returned. If any pwq |
3064 | * has in flight commands, its pwq->flush_color is set to |
3065 | * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq |
3066 | * wakeup logic is armed and %true is returned. |
3067 | * |
3068 | * The caller should have initialized @wq->first_flusher prior to |
3069 | * calling this function with non-negative @flush_color. If |
3070 | * @flush_color is negative, no flush color update is done and %false |
3071 | * is returned. |
3072 | * |
3073 | * If @work_color is non-negative, all pwqs should have the same |
3074 | * work_color which is previous to @work_color and all will be |
3075 | * advanced to @work_color. |
3076 | * |
3077 | * CONTEXT: |
3078 | * mutex_lock(wq->mutex). |
3079 | * |
3080 | * Return: |
3081 | * %true if @flush_color >= 0 and there's something to flush. %false |
3082 | * otherwise. |
3083 | */ |
3084 | static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, |
3085 | int flush_color, int work_color) |
3086 | { |
3087 | bool wait = false; |
3088 | struct pool_workqueue *pwq; |
3089 | |
3090 | if (flush_color >= 0) { |
3091 | WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); |
3092 | atomic_set(v: &wq->nr_pwqs_to_flush, i: 1); |
3093 | } |
3094 | |
3095 | for_each_pwq(pwq, wq) { |
3096 | struct worker_pool *pool = pwq->pool; |
3097 | |
3098 | raw_spin_lock_irq(&pool->lock); |
3099 | |
3100 | if (flush_color >= 0) { |
3101 | WARN_ON_ONCE(pwq->flush_color != -1); |
3102 | |
3103 | if (pwq->nr_in_flight[flush_color]) { |
3104 | pwq->flush_color = flush_color; |
3105 | atomic_inc(v: &wq->nr_pwqs_to_flush); |
3106 | wait = true; |
3107 | } |
3108 | } |
3109 | |
3110 | if (work_color >= 0) { |
3111 | WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); |
3112 | pwq->work_color = work_color; |
3113 | } |
3114 | |
3115 | raw_spin_unlock_irq(&pool->lock); |
3116 | } |
3117 | |
3118 | if (flush_color >= 0 && atomic_dec_and_test(v: &wq->nr_pwqs_to_flush)) |
3119 | complete(&wq->first_flusher->done); |
3120 | |
3121 | return wait; |
3122 | } |
3123 | |
3124 | /** |
3125 | * __flush_workqueue - ensure that any scheduled work has run to completion. |
3126 | * @wq: workqueue to flush |
3127 | * |
3128 | * This function sleeps until all work items which were queued on entry |
3129 | * have finished execution, but it is not livelocked by new incoming ones. |
3130 | */ |
3131 | void __flush_workqueue(struct workqueue_struct *wq) |
3132 | { |
3133 | struct wq_flusher this_flusher = { |
3134 | .list = LIST_HEAD_INIT(this_flusher.list), |
3135 | .flush_color = -1, |
3136 | .done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, wq->lockdep_map), |
3137 | }; |
3138 | int next_color; |
3139 | |
3140 | if (WARN_ON(!wq_online)) |
3141 | return; |
3142 | |
3143 | lock_map_acquire(&wq->lockdep_map); |
3144 | lock_map_release(&wq->lockdep_map); |
3145 | |
3146 | mutex_lock(&wq->mutex); |
3147 | |
3148 | /* |
3149 | * Start-to-wait phase |
3150 | */ |
3151 | next_color = work_next_color(color: wq->work_color); |
3152 | |
3153 | if (next_color != wq->flush_color) { |
3154 | /* |
3155 | * Color space is not full. The current work_color |
3156 | * becomes our flush_color and work_color is advanced |
3157 | * by one. |
3158 | */ |
3159 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); |
3160 | this_flusher.flush_color = wq->work_color; |
3161 | wq->work_color = next_color; |
3162 | |
3163 | if (!wq->first_flusher) { |
3164 | /* no flush in progress, become the first flusher */ |
3165 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); |
3166 | |
3167 | wq->first_flusher = &this_flusher; |
3168 | |
3169 | if (!flush_workqueue_prep_pwqs(wq, flush_color: wq->flush_color, |
3170 | work_color: wq->work_color)) { |
3171 | /* nothing to flush, done */ |
3172 | wq->flush_color = next_color; |
3173 | wq->first_flusher = NULL; |
3174 | goto out_unlock; |
3175 | } |
3176 | } else { |
3177 | /* wait in queue */ |
3178 | WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); |
3179 | list_add_tail(new: &this_flusher.list, head: &wq->flusher_queue); |
3180 | flush_workqueue_prep_pwqs(wq, flush_color: -1, work_color: wq->work_color); |
3181 | } |
3182 | } else { |
3183 | /* |
3184 | * Oops, color space is full, wait on overflow queue. |
3185 | * The next flush completion will assign us |
3186 | * flush_color and transfer to flusher_queue. |
3187 | */ |
3188 | list_add_tail(new: &this_flusher.list, head: &wq->flusher_overflow); |
3189 | } |
3190 | |
3191 | check_flush_dependency(target_wq: wq, NULL); |
3192 | |
3193 | mutex_unlock(lock: &wq->mutex); |
3194 | |
3195 | wait_for_completion(&this_flusher.done); |
3196 | |
3197 | /* |
3198 | * Wake-up-and-cascade phase |
3199 | * |
3200 | * First flushers are responsible for cascading flushes and |
3201 | * handling overflow. Non-first flushers can simply return. |
3202 | */ |
3203 | if (READ_ONCE(wq->first_flusher) != &this_flusher) |
3204 | return; |
3205 | |
3206 | mutex_lock(&wq->mutex); |
3207 | |
3208 | /* we might have raced, check again with mutex held */ |
3209 | if (wq->first_flusher != &this_flusher) |
3210 | goto out_unlock; |
3211 | |
3212 | WRITE_ONCE(wq->first_flusher, NULL); |
3213 | |
3214 | WARN_ON_ONCE(!list_empty(&this_flusher.list)); |
3215 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); |
3216 | |
3217 | while (true) { |
3218 | struct wq_flusher *next, *tmp; |
3219 | |
3220 | /* complete all the flushers sharing the current flush color */ |
3221 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
3222 | if (next->flush_color != wq->flush_color) |
3223 | break; |
3224 | list_del_init(entry: &next->list); |
3225 | complete(&next->done); |
3226 | } |
3227 | |
3228 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && |
3229 | wq->flush_color != work_next_color(wq->work_color)); |
3230 | |
3231 | /* this flush_color is finished, advance by one */ |
3232 | wq->flush_color = work_next_color(color: wq->flush_color); |
3233 | |
3234 | /* one color has been freed, handle overflow queue */ |
3235 | if (!list_empty(head: &wq->flusher_overflow)) { |
3236 | /* |
3237 | * Assign the same color to all overflowed |
3238 | * flushers, advance work_color and append to |
3239 | * flusher_queue. This is the start-to-wait |
3240 | * phase for these overflowed flushers. |
3241 | */ |
3242 | list_for_each_entry(tmp, &wq->flusher_overflow, list) |
3243 | tmp->flush_color = wq->work_color; |
3244 | |
3245 | wq->work_color = work_next_color(color: wq->work_color); |
3246 | |
3247 | list_splice_tail_init(list: &wq->flusher_overflow, |
3248 | head: &wq->flusher_queue); |
3249 | flush_workqueue_prep_pwqs(wq, flush_color: -1, work_color: wq->work_color); |
3250 | } |
3251 | |
3252 | if (list_empty(head: &wq->flusher_queue)) { |
3253 | WARN_ON_ONCE(wq->flush_color != wq->work_color); |
3254 | break; |
3255 | } |
3256 | |
3257 | /* |
3258 | * Need to flush more colors. Make the next flusher |
3259 | * the new first flusher and arm pwqs. |
3260 | */ |
3261 | WARN_ON_ONCE(wq->flush_color == wq->work_color); |
3262 | WARN_ON_ONCE(wq->flush_color != next->flush_color); |
3263 | |
3264 | list_del_init(entry: &next->list); |
3265 | wq->first_flusher = next; |
3266 | |
3267 | if (flush_workqueue_prep_pwqs(wq, flush_color: wq->flush_color, work_color: -1)) |
3268 | break; |
3269 | |
3270 | /* |
3271 | * Meh... this color is already done, clear first |
3272 | * flusher and repeat cascading. |
3273 | */ |
3274 | wq->first_flusher = NULL; |
3275 | } |
3276 | |
3277 | out_unlock: |
3278 | mutex_unlock(lock: &wq->mutex); |
3279 | } |
3280 | EXPORT_SYMBOL(__flush_workqueue); |
3281 | |
3282 | /** |
3283 | * drain_workqueue - drain a workqueue |
3284 | * @wq: workqueue to drain |
3285 | * |
3286 | * Wait until the workqueue becomes empty. While draining is in progress, |
3287 | * only chain queueing is allowed. IOW, only currently pending or running |
3288 | * work items on @wq can queue further work items on it. @wq is flushed |
3289 | * repeatedly until it becomes empty. The number of flushing is determined |
3290 | * by the depth of chaining and should be relatively short. Whine if it |
3291 | * takes too long. |
3292 | */ |
3293 | void drain_workqueue(struct workqueue_struct *wq) |
3294 | { |
3295 | unsigned int flush_cnt = 0; |
3296 | struct pool_workqueue *pwq; |
3297 | |
3298 | /* |
3299 | * __queue_work() needs to test whether there are drainers, is much |
3300 | * hotter than drain_workqueue() and already looks at @wq->flags. |
3301 | * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. |
3302 | */ |
3303 | mutex_lock(&wq->mutex); |
3304 | if (!wq->nr_drainers++) |
3305 | wq->flags |= __WQ_DRAINING; |
3306 | mutex_unlock(lock: &wq->mutex); |
3307 | reflush: |
3308 | __flush_workqueue(wq); |
3309 | |
3310 | mutex_lock(&wq->mutex); |
3311 | |
3312 | for_each_pwq(pwq, wq) { |
3313 | bool drained; |
3314 | |
3315 | raw_spin_lock_irq(&pwq->pool->lock); |
3316 | drained = !pwq->nr_active && list_empty(head: &pwq->inactive_works); |
3317 | raw_spin_unlock_irq(&pwq->pool->lock); |
3318 | |
3319 | if (drained) |
3320 | continue; |
3321 | |
3322 | if (++flush_cnt == 10 || |
3323 | (flush_cnt % 100 == 0 && flush_cnt <= 1000)) |
3324 | pr_warn("workqueue %s: %s() isn't complete after %u tries\n" , |
3325 | wq->name, __func__, flush_cnt); |
3326 | |
3327 | mutex_unlock(lock: &wq->mutex); |
3328 | goto reflush; |
3329 | } |
3330 | |
3331 | if (!--wq->nr_drainers) |
3332 | wq->flags &= ~__WQ_DRAINING; |
3333 | mutex_unlock(lock: &wq->mutex); |
3334 | } |
3335 | EXPORT_SYMBOL_GPL(drain_workqueue); |
3336 | |
3337 | static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, |
3338 | bool from_cancel) |
3339 | { |
3340 | struct worker *worker = NULL; |
3341 | struct worker_pool *pool; |
3342 | struct pool_workqueue *pwq; |
3343 | |
3344 | might_sleep(); |
3345 | |
3346 | rcu_read_lock(); |
3347 | pool = get_work_pool(work); |
3348 | if (!pool) { |
3349 | rcu_read_unlock(); |
3350 | return false; |
3351 | } |
3352 | |
3353 | raw_spin_lock_irq(&pool->lock); |
3354 | /* see the comment in try_to_grab_pending() with the same code */ |
3355 | pwq = get_work_pwq(work); |
3356 | if (pwq) { |
3357 | if (unlikely(pwq->pool != pool)) |
3358 | goto already_gone; |
3359 | } else { |
3360 | worker = find_worker_executing_work(pool, work); |
3361 | if (!worker) |
3362 | goto already_gone; |
3363 | pwq = worker->current_pwq; |
3364 | } |
3365 | |
3366 | check_flush_dependency(target_wq: pwq->wq, target_work: work); |
3367 | |
3368 | insert_wq_barrier(pwq, barr, target: work, worker); |
3369 | raw_spin_unlock_irq(&pool->lock); |
3370 | |
3371 | /* |
3372 | * Force a lock recursion deadlock when using flush_work() inside a |
3373 | * single-threaded or rescuer equipped workqueue. |
3374 | * |
3375 | * For single threaded workqueues the deadlock happens when the work |
3376 | * is after the work issuing the flush_work(). For rescuer equipped |
3377 | * workqueues the deadlock happens when the rescuer stalls, blocking |
3378 | * forward progress. |
3379 | */ |
3380 | if (!from_cancel && |
3381 | (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)) { |
3382 | lock_map_acquire(&pwq->wq->lockdep_map); |
3383 | lock_map_release(&pwq->wq->lockdep_map); |
3384 | } |
3385 | rcu_read_unlock(); |
3386 | return true; |
3387 | already_gone: |
3388 | raw_spin_unlock_irq(&pool->lock); |
3389 | rcu_read_unlock(); |
3390 | return false; |
3391 | } |
3392 | |
3393 | static bool __flush_work(struct work_struct *work, bool from_cancel) |
3394 | { |
3395 | struct wq_barrier barr; |
3396 | |
3397 | if (WARN_ON(!wq_online)) |
3398 | return false; |
3399 | |
3400 | if (WARN_ON(!work->func)) |
3401 | return false; |
3402 | |
3403 | lock_map_acquire(&work->lockdep_map); |
3404 | lock_map_release(&work->lockdep_map); |
3405 | |
3406 | if (start_flush_work(work, barr: &barr, from_cancel)) { |
3407 | wait_for_completion(&barr.done); |
3408 | destroy_work_on_stack(&barr.work); |
3409 | return true; |
3410 | } else { |
3411 | return false; |
3412 | } |
3413 | } |
3414 | |
3415 | /** |
3416 | * flush_work - wait for a work to finish executing the last queueing instance |
3417 | * @work: the work to flush |
3418 | * |
3419 | * Wait until @work has finished execution. @work is guaranteed to be idle |
3420 | * on return if it hasn't been requeued since flush started. |
3421 | * |
3422 | * Return: |
3423 | * %true if flush_work() waited for the work to finish execution, |
3424 | * %false if it was already idle. |
3425 | */ |
3426 | bool flush_work(struct work_struct *work) |
3427 | { |
3428 | return __flush_work(work, from_cancel: false); |
3429 | } |
3430 | EXPORT_SYMBOL_GPL(flush_work); |
3431 | |
3432 | struct cwt_wait { |
3433 | wait_queue_entry_t wait; |
3434 | struct work_struct *work; |
3435 | }; |
3436 | |
3437 | static int cwt_wakefn(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) |
3438 | { |
3439 | struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait); |
3440 | |
3441 | if (cwait->work != key) |
3442 | return 0; |
3443 | return autoremove_wake_function(wq_entry: wait, mode, sync, key); |
3444 | } |
3445 | |
3446 | static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) |
3447 | { |
3448 | static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq); |
3449 | unsigned long flags; |
3450 | int ret; |
3451 | |
3452 | do { |
3453 | ret = try_to_grab_pending(work, is_dwork, flags: &flags); |
3454 | /* |
3455 | * If someone else is already canceling, wait for it to |
3456 | * finish. flush_work() doesn't work for PREEMPT_NONE |
3457 | * because we may get scheduled between @work's completion |
3458 | * and the other canceling task resuming and clearing |
3459 | * CANCELING - flush_work() will return false immediately |
3460 | * as @work is no longer busy, try_to_grab_pending() will |
3461 | * return -ENOENT as @work is still being canceled and the |
3462 | * other canceling task won't be able to clear CANCELING as |
3463 | * we're hogging the CPU. |
3464 | * |
3465 | * Let's wait for completion using a waitqueue. As this |
3466 | * may lead to the thundering herd problem, use a custom |
3467 | * wake function which matches @work along with exclusive |
3468 | * wait and wakeup. |
3469 | */ |
3470 | if (unlikely(ret == -ENOENT)) { |
3471 | struct cwt_wait cwait; |
3472 | |
3473 | init_wait(&cwait.wait); |
3474 | cwait.wait.func = cwt_wakefn; |
3475 | cwait.work = work; |
3476 | |
3477 | prepare_to_wait_exclusive(wq_head: &cancel_waitq, wq_entry: &cwait.wait, |
3478 | TASK_UNINTERRUPTIBLE); |
3479 | if (work_is_canceling(work)) |
3480 | schedule(); |
3481 | finish_wait(wq_head: &cancel_waitq, wq_entry: &cwait.wait); |
3482 | } |
3483 | } while (unlikely(ret < 0)); |
3484 | |
3485 | /* tell other tasks trying to grab @work to back off */ |
3486 | mark_work_canceling(work); |
3487 | local_irq_restore(flags); |
3488 | |
3489 | /* |
3490 | * This allows canceling during early boot. We know that @work |
3491 | * isn't executing. |
3492 | */ |
3493 | if (wq_online) |
3494 | __flush_work(work, from_cancel: true); |
3495 | |
3496 | clear_work_data(work); |
3497 | |
3498 | /* |
3499 | * Paired with prepare_to_wait() above so that either |
3500 | * waitqueue_active() is visible here or !work_is_canceling() is |
3501 | * visible there. |
3502 | */ |
3503 | smp_mb(); |
3504 | if (waitqueue_active(wq_head: &cancel_waitq)) |
3505 | __wake_up(wq_head: &cancel_waitq, TASK_NORMAL, nr: 1, key: work); |
3506 | |
3507 | return ret; |
3508 | } |
3509 | |
3510 | /** |
3511 | * cancel_work_sync - cancel a work and wait for it to finish |
3512 | * @work: the work to cancel |
3513 | * |
3514 | * Cancel @work and wait for its execution to finish. This function |
3515 | * can be used even if the work re-queues itself or migrates to |
3516 | * another workqueue. On return from this function, @work is |
3517 | * guaranteed to be not pending or executing on any CPU. |
3518 | * |
3519 | * cancel_work_sync(&delayed_work->work) must not be used for |
3520 | * delayed_work's. Use cancel_delayed_work_sync() instead. |
3521 | * |
3522 | * The caller must ensure that the workqueue on which @work was last |
3523 | * queued can't be destroyed before this function returns. |
3524 | * |
3525 | * Return: |
3526 | * %true if @work was pending, %false otherwise. |
3527 | */ |
3528 | bool cancel_work_sync(struct work_struct *work) |
3529 | { |
3530 | return __cancel_work_timer(work, is_dwork: false); |
3531 | } |
3532 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
3533 | |
3534 | /** |
3535 | * flush_delayed_work - wait for a dwork to finish executing the last queueing |
3536 | * @dwork: the delayed work to flush |
3537 | * |
3538 | * Delayed timer is cancelled and the pending work is queued for |
3539 | * immediate execution. Like flush_work(), this function only |
3540 | * considers the last queueing instance of @dwork. |
3541 | * |
3542 | * Return: |
3543 | * %true if flush_work() waited for the work to finish execution, |
3544 | * %false if it was already idle. |
3545 | */ |
3546 | bool flush_delayed_work(struct delayed_work *dwork) |
3547 | { |
3548 | local_irq_disable(); |
3549 | if (del_timer_sync(timer: &dwork->timer)) |
3550 | __queue_work(cpu: dwork->cpu, wq: dwork->wq, work: &dwork->work); |
3551 | local_irq_enable(); |
3552 | return flush_work(&dwork->work); |
3553 | } |
3554 | EXPORT_SYMBOL(flush_delayed_work); |
3555 | |
3556 | /** |
3557 | * flush_rcu_work - wait for a rwork to finish executing the last queueing |
3558 | * @rwork: the rcu work to flush |
3559 | * |
3560 | * Return: |
3561 | * %true if flush_rcu_work() waited for the work to finish execution, |
3562 | * %false if it was already idle. |
3563 | */ |
3564 | bool flush_rcu_work(struct rcu_work *rwork) |
3565 | { |
3566 | if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) { |
3567 | rcu_barrier(); |
3568 | flush_work(&rwork->work); |
3569 | return true; |
3570 | } else { |
3571 | return flush_work(&rwork->work); |
3572 | } |
3573 | } |
3574 | EXPORT_SYMBOL(flush_rcu_work); |
3575 | |
3576 | static bool __cancel_work(struct work_struct *work, bool is_dwork) |
3577 | { |
3578 | unsigned long flags; |
3579 | int ret; |
3580 | |
3581 | do { |
3582 | ret = try_to_grab_pending(work, is_dwork, flags: &flags); |
3583 | } while (unlikely(ret == -EAGAIN)); |
3584 | |
3585 | if (unlikely(ret < 0)) |
3586 | return false; |
3587 | |
3588 | set_work_pool_and_clear_pending(work, pool_id: get_work_pool_id(work)); |
3589 | local_irq_restore(flags); |
3590 | return ret; |
3591 | } |
3592 | |
3593 | /* |
3594 | * See cancel_delayed_work() |
3595 | */ |
3596 | bool cancel_work(struct work_struct *work) |
3597 | { |
3598 | return __cancel_work(work, is_dwork: false); |
3599 | } |
3600 | EXPORT_SYMBOL(cancel_work); |
3601 | |
3602 | /** |
3603 | * cancel_delayed_work - cancel a delayed work |
3604 | * @dwork: delayed_work to cancel |
3605 | * |
3606 | * Kill off a pending delayed_work. |
3607 | * |
3608 | * Return: %true if @dwork was pending and canceled; %false if it wasn't |
3609 | * pending. |
3610 | * |
3611 | * Note: |
3612 | * The work callback function may still be running on return, unless |
3613 | * it returns %true and the work doesn't re-arm itself. Explicitly flush or |
3614 | * use cancel_delayed_work_sync() to wait on it. |
3615 | * |
3616 | * This function is safe to call from any context including IRQ handler. |
3617 | */ |
3618 | bool cancel_delayed_work(struct delayed_work *dwork) |
3619 | { |
3620 | return __cancel_work(work: &dwork->work, is_dwork: true); |
3621 | } |
3622 | EXPORT_SYMBOL(cancel_delayed_work); |
3623 | |
3624 | /** |
3625 | * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish |
3626 | * @dwork: the delayed work cancel |
3627 | * |
3628 | * This is cancel_work_sync() for delayed works. |
3629 | * |
3630 | * Return: |
3631 | * %true if @dwork was pending, %false otherwise. |
3632 | */ |
3633 | bool cancel_delayed_work_sync(struct delayed_work *dwork) |
3634 | { |
3635 | return __cancel_work_timer(work: &dwork->work, is_dwork: true); |
3636 | } |
3637 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
3638 | |
3639 | /** |
3640 | * schedule_on_each_cpu - execute a function synchronously on each online CPU |
3641 | * @func: the function to call |
3642 | * |
3643 | * schedule_on_each_cpu() executes @func on each online CPU using the |
3644 | * system workqueue and blocks until all CPUs have completed. |
3645 | * schedule_on_each_cpu() is very slow. |
3646 | * |
3647 | * Return: |
3648 | * 0 on success, -errno on failure. |
3649 | */ |
3650 | int schedule_on_each_cpu(work_func_t func) |
3651 | { |
3652 | int cpu; |
3653 | struct work_struct __percpu *works; |
3654 | |
3655 | works = alloc_percpu(struct work_struct); |
3656 | if (!works) |
3657 | return -ENOMEM; |
3658 | |
3659 | cpus_read_lock(); |
3660 | |
3661 | for_each_online_cpu(cpu) { |
3662 | struct work_struct *work = per_cpu_ptr(works, cpu); |
3663 | |
3664 | INIT_WORK(work, func); |
3665 | schedule_work_on(cpu, work); |
3666 | } |
3667 | |
3668 | for_each_online_cpu(cpu) |
3669 | flush_work(per_cpu_ptr(works, cpu)); |
3670 | |
3671 | cpus_read_unlock(); |
3672 | free_percpu(pdata: works); |
3673 | return 0; |
3674 | } |
3675 | |
3676 | /** |
3677 | * execute_in_process_context - reliably execute the routine with user context |
3678 | * @fn: the function to execute |
3679 | * @ew: guaranteed storage for the execute work structure (must |
3680 | * be available when the work executes) |
3681 | * |
3682 | * Executes the function immediately if process context is available, |
3683 | * otherwise schedules the function for delayed execution. |
3684 | * |
3685 | * Return: 0 - function was executed |
3686 | * 1 - function was scheduled for execution |
3687 | */ |
3688 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
3689 | { |
3690 | if (!in_interrupt()) { |
3691 | fn(&ew->work); |
3692 | return 0; |
3693 | } |
3694 | |
3695 | INIT_WORK(&ew->work, fn); |
3696 | schedule_work(work: &ew->work); |
3697 | |
3698 | return 1; |
3699 | } |
3700 | EXPORT_SYMBOL_GPL(execute_in_process_context); |
3701 | |
3702 | /** |
3703 | * free_workqueue_attrs - free a workqueue_attrs |
3704 | * @attrs: workqueue_attrs to free |
3705 | * |
3706 | * Undo alloc_workqueue_attrs(). |
3707 | */ |
3708 | void free_workqueue_attrs(struct workqueue_attrs *attrs) |
3709 | { |
3710 | if (attrs) { |
3711 | free_cpumask_var(mask: attrs->cpumask); |
3712 | free_cpumask_var(mask: attrs->__pod_cpumask); |
3713 | kfree(objp: attrs); |
3714 | } |
3715 | } |
3716 | |
3717 | /** |
3718 | * alloc_workqueue_attrs - allocate a workqueue_attrs |
3719 | * |
3720 | * Allocate a new workqueue_attrs, initialize with default settings and |
3721 | * return it. |
3722 | * |
3723 | * Return: The allocated new workqueue_attr on success. %NULL on failure. |
3724 | */ |
3725 | struct workqueue_attrs *alloc_workqueue_attrs(void) |
3726 | { |
3727 | struct workqueue_attrs *attrs; |
3728 | |
3729 | attrs = kzalloc(size: sizeof(*attrs), GFP_KERNEL); |
3730 | if (!attrs) |
3731 | goto fail; |
3732 | if (!alloc_cpumask_var(mask: &attrs->cpumask, GFP_KERNEL)) |
3733 | goto fail; |
3734 | if (!alloc_cpumask_var(mask: &attrs->__pod_cpumask, GFP_KERNEL)) |
3735 | goto fail; |
3736 | |
3737 | cpumask_copy(dstp: attrs->cpumask, cpu_possible_mask); |
3738 | attrs->affn_scope = WQ_AFFN_DFL; |
3739 | return attrs; |
3740 | fail: |
3741 | free_workqueue_attrs(attrs); |
3742 | return NULL; |
3743 | } |
3744 | |
3745 | static void copy_workqueue_attrs(struct workqueue_attrs *to, |
3746 | const struct workqueue_attrs *from) |
3747 | { |
3748 | to->nice = from->nice; |
3749 | cpumask_copy(dstp: to->cpumask, srcp: from->cpumask); |
3750 | cpumask_copy(dstp: to->__pod_cpumask, srcp: from->__pod_cpumask); |
3751 | to->affn_strict = from->affn_strict; |
3752 | |
3753 | /* |
3754 | * Unlike hash and equality test, copying shouldn't ignore wq-only |
3755 | * fields as copying is used for both pool and wq attrs. Instead, |
3756 | * get_unbound_pool() explicitly clears the fields. |
3757 | */ |
3758 | to->affn_scope = from->affn_scope; |
3759 | to->ordered = from->ordered; |
3760 | } |
3761 | |
3762 | /* |
3763 | * Some attrs fields are workqueue-only. Clear them for worker_pool's. See the |
3764 | * comments in 'struct workqueue_attrs' definition. |
3765 | */ |
3766 | static void wqattrs_clear_for_pool(struct workqueue_attrs *attrs) |
3767 | { |
3768 | attrs->affn_scope = WQ_AFFN_NR_TYPES; |
3769 | attrs->ordered = false; |
3770 | } |
3771 | |
3772 | /* hash value of the content of @attr */ |
3773 | static u32 wqattrs_hash(const struct workqueue_attrs *attrs) |
3774 | { |
3775 | u32 hash = 0; |
3776 | |
3777 | hash = jhash_1word(a: attrs->nice, initval: hash); |
3778 | hash = jhash(cpumask_bits(attrs->cpumask), |
3779 | BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), initval: hash); |
3780 | hash = jhash(cpumask_bits(attrs->__pod_cpumask), |
3781 | BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), initval: hash); |
3782 | hash = jhash_1word(a: attrs->affn_strict, initval: hash); |
3783 | return hash; |
3784 | } |
3785 | |
3786 | /* content equality test */ |
3787 | static bool wqattrs_equal(const struct workqueue_attrs *a, |
3788 | const struct workqueue_attrs *b) |
3789 | { |
3790 | if (a->nice != b->nice) |
3791 | return false; |
3792 | if (!cpumask_equal(src1p: a->cpumask, src2p: b->cpumask)) |
3793 | return false; |
3794 | if (!cpumask_equal(src1p: a->__pod_cpumask, src2p: b->__pod_cpumask)) |
3795 | return false; |
3796 | if (a->affn_strict != b->affn_strict) |
3797 | return false; |
3798 | return true; |
3799 | } |
3800 | |
3801 | /* Update @attrs with actually available CPUs */ |
3802 | static void wqattrs_actualize_cpumask(struct workqueue_attrs *attrs, |
3803 | const cpumask_t *unbound_cpumask) |
3804 | { |
3805 | /* |
3806 | * Calculate the effective CPU mask of @attrs given @unbound_cpumask. If |
3807 | * @attrs->cpumask doesn't overlap with @unbound_cpumask, we fallback to |
3808 | * @unbound_cpumask. |
3809 | */ |
3810 | cpumask_and(dstp: attrs->cpumask, src1p: attrs->cpumask, src2p: unbound_cpumask); |
3811 | if (unlikely(cpumask_empty(attrs->cpumask))) |
3812 | cpumask_copy(dstp: attrs->cpumask, srcp: unbound_cpumask); |
3813 | } |
3814 | |
3815 | /* find wq_pod_type to use for @attrs */ |
3816 | static const struct wq_pod_type * |
3817 | wqattrs_pod_type(const struct workqueue_attrs *attrs) |
3818 | { |
3819 | enum wq_affn_scope scope; |
3820 | struct wq_pod_type *pt; |
3821 | |
3822 | /* to synchronize access to wq_affn_dfl */ |
3823 | lockdep_assert_held(&wq_pool_mutex); |
3824 | |
3825 | if (attrs->affn_scope == WQ_AFFN_DFL) |
3826 | scope = wq_affn_dfl; |
3827 | else |
3828 | scope = attrs->affn_scope; |
3829 | |
3830 | pt = &wq_pod_types[scope]; |
3831 | |
3832 | if (!WARN_ON_ONCE(attrs->affn_scope == WQ_AFFN_NR_TYPES) && |
3833 | likely(pt->nr_pods)) |
3834 | return pt; |
3835 | |
3836 | /* |
3837 | * Before workqueue_init_topology(), only SYSTEM is available which is |
3838 | * initialized in workqueue_init_early(). |
3839 | */ |
3840 | pt = &wq_pod_types[WQ_AFFN_SYSTEM]; |
3841 | BUG_ON(!pt->nr_pods); |
3842 | return pt; |
3843 | } |
3844 | |
3845 | /** |
3846 | * init_worker_pool - initialize a newly zalloc'd worker_pool |
3847 | * @pool: worker_pool to initialize |
3848 | * |
3849 | * Initialize a newly zalloc'd @pool. It also allocates @pool->attrs. |
3850 | * |
3851 | * Return: 0 on success, -errno on failure. Even on failure, all fields |
3852 | * inside @pool proper are initialized and put_unbound_pool() can be called |
3853 | * on @pool safely to release it. |
3854 | */ |
3855 | static int init_worker_pool(struct worker_pool *pool) |
3856 | { |
3857 | raw_spin_lock_init(&pool->lock); |
3858 | pool->id = -1; |
3859 | pool->cpu = -1; |
3860 | pool->node = NUMA_NO_NODE; |
3861 | pool->flags |= POOL_DISASSOCIATED; |
3862 | pool->watchdog_ts = jiffies; |
3863 | INIT_LIST_HEAD(list: &pool->worklist); |
3864 | INIT_LIST_HEAD(list: &pool->idle_list); |
3865 | hash_init(pool->busy_hash); |
3866 | |
3867 | timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE); |
3868 | INIT_WORK(&pool->idle_cull_work, idle_cull_fn); |
3869 | |
3870 | timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0); |
3871 | |
3872 | INIT_LIST_HEAD(list: &pool->workers); |
3873 | INIT_LIST_HEAD(list: &pool->dying_workers); |
3874 | |
3875 | ida_init(ida: &pool->worker_ida); |
3876 | INIT_HLIST_NODE(h: &pool->hash_node); |
3877 | pool->refcnt = 1; |
3878 | |
3879 | /* shouldn't fail above this point */ |
3880 | pool->attrs = alloc_workqueue_attrs(); |
3881 | if (!pool->attrs) |
3882 | return -ENOMEM; |
3883 | |
3884 | wqattrs_clear_for_pool(attrs: pool->attrs); |
3885 | |
3886 | return 0; |
3887 | } |
3888 | |
3889 | #ifdef CONFIG_LOCKDEP |
3890 | static void wq_init_lockdep(struct workqueue_struct *wq) |
3891 | { |
3892 | char *lock_name; |
3893 | |
3894 | lockdep_register_key(key: &wq->key); |
3895 | lock_name = kasprintf(GFP_KERNEL, fmt: "%s%s" , "(wq_completion)" , wq->name); |
3896 | if (!lock_name) |
3897 | lock_name = wq->name; |
3898 | |
3899 | wq->lock_name = lock_name; |
3900 | lockdep_init_map(lock: &wq->lockdep_map, name: lock_name, key: &wq->key, subclass: 0); |
3901 | } |
3902 | |
3903 | static void wq_unregister_lockdep(struct workqueue_struct *wq) |
3904 | { |
3905 | lockdep_unregister_key(key: &wq->key); |
3906 | } |
3907 | |
3908 | static void wq_free_lockdep(struct workqueue_struct *wq) |
3909 | { |
3910 | if (wq->lock_name != wq->name) |
3911 | kfree(objp: wq->lock_name); |
3912 | } |
3913 | #else |
3914 | static void wq_init_lockdep(struct workqueue_struct *wq) |
3915 | { |
3916 | } |
3917 | |
3918 | static void wq_unregister_lockdep(struct workqueue_struct *wq) |
3919 | { |
3920 | } |
3921 | |
3922 | static void wq_free_lockdep(struct workqueue_struct *wq) |
3923 | { |
3924 | } |
3925 | #endif |
3926 | |
3927 | static void rcu_free_wq(struct rcu_head *rcu) |
3928 | { |
3929 | struct workqueue_struct *wq = |
3930 | container_of(rcu, struct workqueue_struct, rcu); |
3931 | |
3932 | wq_free_lockdep(wq); |
3933 | free_percpu(pdata: wq->cpu_pwq); |
3934 | free_workqueue_attrs(attrs: wq->unbound_attrs); |
3935 | kfree(objp: wq); |
3936 | } |
3937 | |
3938 | static void rcu_free_pool(struct rcu_head *rcu) |
3939 | { |
3940 | struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); |
3941 | |
3942 | ida_destroy(ida: &pool->worker_ida); |
3943 | free_workqueue_attrs(attrs: pool->attrs); |
3944 | kfree(objp: pool); |
3945 | } |
3946 | |
3947 | /** |
3948 | * put_unbound_pool - put a worker_pool |
3949 | * @pool: worker_pool to put |
3950 | * |
3951 | * Put @pool. If its refcnt reaches zero, it gets destroyed in RCU |
3952 | * safe manner. get_unbound_pool() calls this function on its failure path |
3953 | * and this function should be able to release pools which went through, |
3954 | * successfully or not, init_worker_pool(). |
3955 | * |
3956 | * Should be called with wq_pool_mutex held. |
3957 | */ |
3958 | static void put_unbound_pool(struct worker_pool *pool) |
3959 | { |
3960 | DECLARE_COMPLETION_ONSTACK(detach_completion); |
3961 | struct worker *worker; |
3962 | LIST_HEAD(cull_list); |
3963 | |
3964 | lockdep_assert_held(&wq_pool_mutex); |
3965 | |
3966 | if (--pool->refcnt) |
3967 | return; |
3968 | |
3969 | /* sanity checks */ |
3970 | if (WARN_ON(!(pool->cpu < 0)) || |
3971 | WARN_ON(!list_empty(&pool->worklist))) |
3972 | return; |
3973 | |
3974 | /* release id and unhash */ |
3975 | if (pool->id >= 0) |
3976 | idr_remove(&worker_pool_idr, id: pool->id); |
3977 | hash_del(node: &pool->hash_node); |
3978 | |
3979 | /* |
3980 | * Become the manager and destroy all workers. This prevents |
3981 | * @pool's workers from blocking on attach_mutex. We're the last |
3982 | * manager and @pool gets freed with the flag set. |
3983 | * |
3984 | * Having a concurrent manager is quite unlikely to happen as we can |
3985 | * only get here with |
3986 | * pwq->refcnt == pool->refcnt == 0 |
3987 | * which implies no work queued to the pool, which implies no worker can |
3988 | * become the manager. However a worker could have taken the role of |
3989 | * manager before the refcnts dropped to 0, since maybe_create_worker() |
3990 | * drops pool->lock |
3991 | */ |
3992 | while (true) { |
3993 | rcuwait_wait_event(&manager_wait, |
3994 | !(pool->flags & POOL_MANAGER_ACTIVE), |
3995 | TASK_UNINTERRUPTIBLE); |
3996 | |
3997 | mutex_lock(&wq_pool_attach_mutex); |
3998 | raw_spin_lock_irq(&pool->lock); |
3999 | if (!(pool->flags & POOL_MANAGER_ACTIVE)) { |
4000 | pool->flags |= POOL_MANAGER_ACTIVE; |
4001 | break; |
4002 | } |
4003 | raw_spin_unlock_irq(&pool->lock); |
4004 | mutex_unlock(lock: &wq_pool_attach_mutex); |
4005 | } |
4006 | |
4007 | while ((worker = first_idle_worker(pool))) |
4008 | set_worker_dying(worker, list: &cull_list); |
4009 | WARN_ON(pool->nr_workers || pool->nr_idle); |
4010 | raw_spin_unlock_irq(&pool->lock); |
4011 | |
4012 | wake_dying_workers(cull_list: &cull_list); |
4013 | |
4014 | if (!list_empty(head: &pool->workers) || !list_empty(head: &pool->dying_workers)) |
4015 | pool->detach_completion = &detach_completion; |
4016 | mutex_unlock(lock: &wq_pool_attach_mutex); |
4017 | |
4018 | if (pool->detach_completion) |
4019 | wait_for_completion(pool->detach_completion); |
4020 | |
4021 | /* shut down the timers */ |
4022 | del_timer_sync(timer: &pool->idle_timer); |
4023 | cancel_work_sync(&pool->idle_cull_work); |
4024 | del_timer_sync(timer: &pool->mayday_timer); |
4025 | |
4026 | /* RCU protected to allow dereferences from get_work_pool() */ |
4027 | call_rcu(head: &pool->rcu, func: rcu_free_pool); |
4028 | } |
4029 | |
4030 | /** |
4031 | * get_unbound_pool - get a worker_pool with the specified attributes |
4032 | * @attrs: the attributes of the worker_pool to get |
4033 | * |
4034 | * Obtain a worker_pool which has the same attributes as @attrs, bump the |
4035 | * reference count and return it. If there already is a matching |
4036 | * worker_pool, it will be used; otherwise, this function attempts to |
4037 | * create a new one. |
4038 | * |
4039 | * Should be called with wq_pool_mutex held. |
4040 | * |
4041 | * Return: On success, a worker_pool with the same attributes as @attrs. |
4042 | * On failure, %NULL. |
4043 | */ |
4044 | static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) |
4045 | { |
4046 | struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_NUMA]; |
4047 | u32 hash = wqattrs_hash(attrs); |
4048 | struct worker_pool *pool; |
4049 | int pod, node = NUMA_NO_NODE; |
4050 | |
4051 | lockdep_assert_held(&wq_pool_mutex); |
4052 | |
4053 | /* do we already have a matching pool? */ |
4054 | hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { |
4055 | if (wqattrs_equal(a: pool->attrs, b: attrs)) { |
4056 | pool->refcnt++; |
4057 | return pool; |
4058 | } |
4059 | } |
4060 | |
4061 | /* If __pod_cpumask is contained inside a NUMA pod, that's our node */ |
4062 | for (pod = 0; pod < pt->nr_pods; pod++) { |
4063 | if (cpumask_subset(src1p: attrs->__pod_cpumask, src2p: pt->pod_cpus[pod])) { |
4064 | node = pt->pod_node[pod]; |
4065 | break; |
4066 | } |
4067 | } |
4068 | |
4069 | /* nope, create a new one */ |
4070 | pool = kzalloc_node(size: sizeof(*pool), GFP_KERNEL, node); |
4071 | if (!pool || init_worker_pool(pool) < 0) |
4072 | goto fail; |
4073 | |
4074 | pool->node = node; |
4075 | copy_workqueue_attrs(to: pool->attrs, from: attrs); |
4076 | wqattrs_clear_for_pool(attrs: pool->attrs); |
4077 | |
4078 | if (worker_pool_assign_id(pool) < 0) |
4079 | goto fail; |
4080 | |
4081 | /* create and start the initial worker */ |
4082 | if (wq_online && !create_worker(pool)) |
4083 | goto fail; |
4084 | |
4085 | /* install */ |
4086 | hash_add(unbound_pool_hash, &pool->hash_node, hash); |
4087 | |
4088 | return pool; |
4089 | fail: |
4090 | if (pool) |
4091 | put_unbound_pool(pool); |
4092 | return NULL; |
4093 | } |
4094 | |
4095 | static void rcu_free_pwq(struct rcu_head *rcu) |
4096 | { |
4097 | kmem_cache_free(s: pwq_cache, |
4098 | container_of(rcu, struct pool_workqueue, rcu)); |
4099 | } |
4100 | |
4101 | /* |
4102 | * Scheduled on pwq_release_worker by put_pwq() when an unbound pwq hits zero |
4103 | * refcnt and needs to be destroyed. |
4104 | */ |
4105 | static void pwq_release_workfn(struct kthread_work *work) |
4106 | { |
4107 | struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, |
4108 | release_work); |
4109 | struct workqueue_struct *wq = pwq->wq; |
4110 | struct worker_pool *pool = pwq->pool; |
4111 | bool is_last = false; |
4112 | |
4113 | /* |
4114 | * When @pwq is not linked, it doesn't hold any reference to the |
4115 | * @wq, and @wq is invalid to access. |
4116 | */ |
4117 | if (!list_empty(head: &pwq->pwqs_node)) { |
4118 | mutex_lock(&wq->mutex); |
4119 | list_del_rcu(entry: &pwq->pwqs_node); |
4120 | is_last = list_empty(head: &wq->pwqs); |
4121 | mutex_unlock(lock: &wq->mutex); |
4122 | } |
4123 | |
4124 | if (wq->flags & WQ_UNBOUND) { |
4125 | mutex_lock(&wq_pool_mutex); |
4126 | put_unbound_pool(pool); |
4127 | mutex_unlock(lock: &wq_pool_mutex); |
4128 | } |
4129 | |
4130 | call_rcu(head: &pwq->rcu, func: rcu_free_pwq); |
4131 | |
4132 | /* |
4133 | * If we're the last pwq going away, @wq is already dead and no one |
4134 | * is gonna access it anymore. Schedule RCU free. |
4135 | */ |
4136 | if (is_last) { |
4137 | wq_unregister_lockdep(wq); |
4138 | call_rcu(head: &wq->rcu, func: rcu_free_wq); |
4139 | } |
4140 | } |
4141 | |
4142 | /** |
4143 | * pwq_adjust_max_active - update a pwq's max_active to the current setting |
4144 | * @pwq: target pool_workqueue |
4145 | * |
4146 | * If @pwq isn't freezing, set @pwq->max_active to the associated |
4147 | * workqueue's saved_max_active and activate inactive work items |
4148 | * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. |
4149 | */ |
4150 | static void pwq_adjust_max_active(struct pool_workqueue *pwq) |
4151 | { |
4152 | struct workqueue_struct *wq = pwq->wq; |
4153 | bool freezable = wq->flags & WQ_FREEZABLE; |
4154 | unsigned long flags; |
4155 | |
4156 | /* for @wq->saved_max_active */ |
4157 | lockdep_assert_held(&wq->mutex); |
4158 | |
4159 | /* fast exit for non-freezable wqs */ |
4160 | if (!freezable && pwq->max_active == wq->saved_max_active) |
4161 | return; |
4162 | |
4163 | /* this function can be called during early boot w/ irq disabled */ |
4164 | raw_spin_lock_irqsave(&pwq->pool->lock, flags); |
4165 | |
4166 | /* |
4167 | * During [un]freezing, the caller is responsible for ensuring that |
4168 | * this function is called at least once after @workqueue_freezing |
4169 | * is updated and visible. |
4170 | */ |
4171 | if (!freezable || !workqueue_freezing) { |
4172 | pwq->max_active = wq->saved_max_active; |
4173 | |
4174 | while (!list_empty(head: &pwq->inactive_works) && |
4175 | pwq->nr_active < pwq->max_active) |
4176 | pwq_activate_first_inactive(pwq); |
4177 | |
4178 | kick_pool(pool: pwq->pool); |
4179 | } else { |
4180 | pwq->max_active = 0; |
4181 | } |
4182 | |
4183 | raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); |
4184 | } |
4185 | |
4186 | /* initialize newly allocated @pwq which is associated with @wq and @pool */ |
4187 | static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, |
4188 | struct worker_pool *pool) |
4189 | { |
4190 | BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); |
4191 | |
4192 | memset(pwq, 0, sizeof(*pwq)); |
4193 | |
4194 | pwq->pool = pool; |
4195 | pwq->wq = wq; |
4196 | pwq->flush_color = -1; |
4197 | pwq->refcnt = 1; |
4198 | INIT_LIST_HEAD(list: &pwq->inactive_works); |
4199 | INIT_LIST_HEAD(list: &pwq->pwqs_node); |
4200 | INIT_LIST_HEAD(list: &pwq->mayday_node); |
4201 | kthread_init_work(&pwq->release_work, pwq_release_workfn); |
4202 | } |
4203 | |
4204 | /* sync @pwq with the current state of its associated wq and link it */ |
4205 | static void link_pwq(struct pool_workqueue *pwq) |
4206 | { |
4207 | struct workqueue_struct *wq = pwq->wq; |
4208 | |
4209 | lockdep_assert_held(&wq->mutex); |
4210 | |
4211 | /* may be called multiple times, ignore if already linked */ |
4212 | if (!list_empty(head: &pwq->pwqs_node)) |
4213 | return; |
4214 | |
4215 | /* set the matching work_color */ |
4216 | pwq->work_color = wq->work_color; |
4217 | |
4218 | /* sync max_active to the current setting */ |
4219 | pwq_adjust_max_active(pwq); |
4220 | |
4221 | /* link in @pwq */ |
4222 | list_add_rcu(new: &pwq->pwqs_node, head: &wq->pwqs); |
4223 | } |
4224 | |
4225 | /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ |
4226 | static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, |
4227 | const struct workqueue_attrs *attrs) |
4228 | { |
4229 | struct worker_pool *pool; |
4230 | struct pool_workqueue *pwq; |
4231 | |
4232 | lockdep_assert_held(&wq_pool_mutex); |
4233 | |
4234 | pool = get_unbound_pool(attrs); |
4235 | if (!pool) |
4236 | return NULL; |
4237 | |
4238 | pwq = kmem_cache_alloc_node(s: pwq_cache, GFP_KERNEL, node: pool->node); |
4239 | if (!pwq) { |
4240 | put_unbound_pool(pool); |
4241 | return NULL; |
4242 | } |
4243 | |
4244 | init_pwq(pwq, wq, pool); |
4245 | return pwq; |
4246 | } |
4247 | |
4248 | /** |
4249 | * wq_calc_pod_cpumask - calculate a wq_attrs' cpumask for a pod |
4250 | * @attrs: the wq_attrs of the default pwq of the target workqueue |
4251 | * @cpu: the target CPU |
4252 | * @cpu_going_down: if >= 0, the CPU to consider as offline |
4253 | * |
4254 | * Calculate the cpumask a workqueue with @attrs should use on @pod. If |
4255 | * @cpu_going_down is >= 0, that cpu is considered offline during calculation. |
4256 | * The result is stored in @attrs->__pod_cpumask. |
4257 | * |
4258 | * If pod affinity is not enabled, @attrs->cpumask is always used. If enabled |
4259 | * and @pod has online CPUs requested by @attrs, the returned cpumask is the |
4260 | * intersection of the possible CPUs of @pod and @attrs->cpumask. |
4261 | * |
4262 | * The caller is responsible for ensuring that the cpumask of @pod stays stable. |
4263 | */ |
4264 | static void wq_calc_pod_cpumask(struct workqueue_attrs *attrs, int cpu, |
4265 | int cpu_going_down) |
4266 | { |
4267 | const struct wq_pod_type *pt = wqattrs_pod_type(attrs); |
4268 | int pod = pt->cpu_pod[cpu]; |
4269 | |
4270 | /* does @pod have any online CPUs @attrs wants? */ |
4271 | cpumask_and(dstp: attrs->__pod_cpumask, src1p: pt->pod_cpus[pod], src2p: attrs->cpumask); |
4272 | cpumask_and(dstp: attrs->__pod_cpumask, src1p: attrs->__pod_cpumask, cpu_online_mask); |
4273 | if (cpu_going_down >= 0) |
4274 | cpumask_clear_cpu(cpu: cpu_going_down, dstp: attrs->__pod_cpumask); |
4275 | |
4276 | if (cpumask_empty(srcp: attrs->__pod_cpumask)) { |
4277 | cpumask_copy(dstp: attrs->__pod_cpumask, srcp: attrs->cpumask); |
4278 | return; |
4279 | } |
4280 | |
4281 | /* yeap, return possible CPUs in @pod that @attrs wants */ |
4282 | cpumask_and(dstp: attrs->__pod_cpumask, src1p: attrs->cpumask, src2p: pt->pod_cpus[pod]); |
4283 | |
4284 | if (cpumask_empty(srcp: attrs->__pod_cpumask)) |
4285 | pr_warn_once("WARNING: workqueue cpumask: online intersect > " |
4286 | "possible intersect\n" ); |
4287 | } |
4288 | |
4289 | /* install @pwq into @wq's cpu_pwq and return the old pwq */ |
4290 | static struct pool_workqueue *install_unbound_pwq(struct workqueue_struct *wq, |
4291 | int cpu, struct pool_workqueue *pwq) |
4292 | { |
4293 | struct pool_workqueue *old_pwq; |
4294 | |
4295 | lockdep_assert_held(&wq_pool_mutex); |
4296 | lockdep_assert_held(&wq->mutex); |
4297 | |
4298 | /* link_pwq() can handle duplicate calls */ |
4299 | link_pwq(pwq); |
4300 | |
4301 | old_pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu)); |
4302 | rcu_assign_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu), pwq); |
4303 | return old_pwq; |
4304 | } |
4305 | |
4306 | /* context to store the prepared attrs & pwqs before applying */ |
4307 | struct apply_wqattrs_ctx { |
4308 | struct workqueue_struct *wq; /* target workqueue */ |
4309 | struct workqueue_attrs *attrs; /* attrs to apply */ |
4310 | struct list_head list; /* queued for batching commit */ |
4311 | struct pool_workqueue *dfl_pwq; |
4312 | struct pool_workqueue *pwq_tbl[]; |
4313 | }; |
4314 | |
4315 | /* free the resources after success or abort */ |
4316 | static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx) |
4317 | { |
4318 | if (ctx) { |
4319 | int cpu; |
4320 | |
4321 | for_each_possible_cpu(cpu) |
4322 | put_pwq_unlocked(pwq: ctx->pwq_tbl[cpu]); |
4323 | put_pwq_unlocked(pwq: ctx->dfl_pwq); |
4324 | |
4325 | free_workqueue_attrs(attrs: ctx->attrs); |
4326 | |
4327 | kfree(objp: ctx); |
4328 | } |
4329 | } |
4330 | |
4331 | /* allocate the attrs and pwqs for later installation */ |
4332 | static struct apply_wqattrs_ctx * |
4333 | apply_wqattrs_prepare(struct workqueue_struct *wq, |
4334 | const struct workqueue_attrs *attrs, |
4335 | const cpumask_var_t unbound_cpumask) |
4336 | { |
4337 | struct apply_wqattrs_ctx *ctx; |
4338 | struct workqueue_attrs *new_attrs; |
4339 | int cpu; |
4340 | |
4341 | lockdep_assert_held(&wq_pool_mutex); |
4342 | |
4343 | if (WARN_ON(attrs->affn_scope < 0 || |
4344 | attrs->affn_scope >= WQ_AFFN_NR_TYPES)) |
4345 | return ERR_PTR(error: -EINVAL); |
4346 | |
4347 | ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_cpu_ids), GFP_KERNEL); |
4348 | |
4349 | new_attrs = alloc_workqueue_attrs(); |
4350 | if (!ctx || !new_attrs) |
4351 | goto out_free; |
4352 | |
4353 | /* |
4354 | * If something goes wrong during CPU up/down, we'll fall back to |
4355 | * the default pwq covering whole @attrs->cpumask. Always create |
4356 | * it even if we don't use it immediately. |
4357 | */ |
4358 | copy_workqueue_attrs(to: new_attrs, from: attrs); |
4359 | wqattrs_actualize_cpumask(attrs: new_attrs, unbound_cpumask); |
4360 | cpumask_copy(dstp: new_attrs->__pod_cpumask, srcp: new_attrs->cpumask); |
4361 | ctx->dfl_pwq = alloc_unbound_pwq(wq, attrs: new_attrs); |
4362 | if (!ctx->dfl_pwq) |
4363 | goto out_free; |
4364 | |
4365 | for_each_possible_cpu(cpu) { |
4366 | if (new_attrs->ordered) { |
4367 | ctx->dfl_pwq->refcnt++; |
4368 | ctx->pwq_tbl[cpu] = ctx->dfl_pwq; |
4369 | } else { |
4370 | wq_calc_pod_cpumask(attrs: new_attrs, cpu, cpu_going_down: -1); |
4371 | ctx->pwq_tbl[cpu] = alloc_unbound_pwq(wq, attrs: new_attrs); |
4372 | if (!ctx->pwq_tbl[cpu]) |
4373 | goto out_free; |
4374 | } |
4375 | } |
4376 | |
4377 | /* save the user configured attrs and sanitize it. */ |
4378 | copy_workqueue_attrs(to: new_attrs, from: attrs); |
4379 | cpumask_and(dstp: new_attrs->cpumask, src1p: new_attrs->cpumask, cpu_possible_mask); |
4380 | cpumask_copy(dstp: new_attrs->__pod_cpumask, srcp: new_attrs->cpumask); |
4381 | ctx->attrs = new_attrs; |
4382 | |
4383 | ctx->wq = wq; |
4384 | return ctx; |
4385 | |
4386 | out_free: |
4387 | free_workqueue_attrs(attrs: new_attrs); |
4388 | apply_wqattrs_cleanup(ctx); |
4389 | return ERR_PTR(error: -ENOMEM); |
4390 | } |
4391 | |
4392 | /* set attrs and install prepared pwqs, @ctx points to old pwqs on return */ |
4393 | static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) |
4394 | { |
4395 | int cpu; |
4396 | |
4397 | /* all pwqs have been created successfully, let's install'em */ |
4398 | mutex_lock(&ctx->wq->mutex); |
4399 | |
4400 | copy_workqueue_attrs(to: ctx->wq->unbound_attrs, from: ctx->attrs); |
4401 | |
4402 | /* save the previous pwq and install the new one */ |
4403 | for_each_possible_cpu(cpu) |
4404 | ctx->pwq_tbl[cpu] = install_unbound_pwq(wq: ctx->wq, cpu, |
4405 | pwq: ctx->pwq_tbl[cpu]); |
4406 | |
4407 | /* @dfl_pwq might not have been used, ensure it's linked */ |
4408 | link_pwq(pwq: ctx->dfl_pwq); |
4409 | swap(ctx->wq->dfl_pwq, ctx->dfl_pwq); |
4410 | |
4411 | mutex_unlock(lock: &ctx->wq->mutex); |
4412 | } |
4413 | |
4414 | static void apply_wqattrs_lock(void) |
4415 | { |
4416 | /* CPUs should stay stable across pwq creations and installations */ |
4417 | cpus_read_lock(); |
4418 | mutex_lock(&wq_pool_mutex); |
4419 | } |
4420 | |
4421 | static void apply_wqattrs_unlock(void) |
4422 | { |
4423 | mutex_unlock(lock: &wq_pool_mutex); |
4424 | cpus_read_unlock(); |
4425 | } |
4426 | |
4427 | static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, |
4428 | const struct workqueue_attrs *attrs) |
4429 | { |
4430 | struct apply_wqattrs_ctx *ctx; |
4431 | |
4432 | /* only unbound workqueues can change attributes */ |
4433 | if (WARN_ON(!(wq->flags & WQ_UNBOUND))) |
4434 | return -EINVAL; |
4435 | |
4436 | /* creating multiple pwqs breaks ordering guarantee */ |
4437 | if (!list_empty(head: &wq->pwqs)) { |
4438 | if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) |
4439 | return -EINVAL; |
4440 | |
4441 | wq->flags &= ~__WQ_ORDERED; |
4442 | } |
4443 | |
4444 | ctx = apply_wqattrs_prepare(wq, attrs, unbound_cpumask: wq_unbound_cpumask); |
4445 | if (IS_ERR(ptr: ctx)) |
4446 | return PTR_ERR(ptr: ctx); |
4447 | |
4448 | /* the ctx has been prepared successfully, let's commit it */ |
4449 | apply_wqattrs_commit(ctx); |
4450 | apply_wqattrs_cleanup(ctx); |
4451 | |
4452 | return 0; |
4453 | } |
4454 | |
4455 | /** |
4456 | * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue |
4457 | * @wq: the target workqueue |
4458 | * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() |
4459 | * |
4460 | * Apply @attrs to an unbound workqueue @wq. Unless disabled, this function maps |
4461 | * a separate pwq to each CPU pod with possibles CPUs in @attrs->cpumask so that |
4462 | * work items are affine to the pod it was issued on. Older pwqs are released as |
4463 | * in-flight work items finish. Note that a work item which repeatedly requeues |
4464 | * itself back-to-back will stay on its current pwq. |
4465 | * |
4466 | * Performs GFP_KERNEL allocations. |
4467 | * |
4468 | * Assumes caller has CPU hotplug read exclusion, i.e. cpus_read_lock(). |
4469 | * |
4470 | * Return: 0 on success and -errno on failure. |
4471 | */ |
4472 | int apply_workqueue_attrs(struct workqueue_struct *wq, |
4473 | const struct workqueue_attrs *attrs) |
4474 | { |
4475 | int ret; |
4476 | |
4477 | lockdep_assert_cpus_held(); |
4478 | |
4479 | mutex_lock(&wq_pool_mutex); |
4480 | ret = apply_workqueue_attrs_locked(wq, attrs); |
4481 | mutex_unlock(lock: &wq_pool_mutex); |
4482 | |
4483 | return ret; |
4484 | } |
4485 | |
4486 | /** |
4487 | * wq_update_pod - update pod affinity of a wq for CPU hot[un]plug |
4488 | * @wq: the target workqueue |
4489 | * @cpu: the CPU to update pool association for |
4490 | * @hotplug_cpu: the CPU coming up or going down |
4491 | * @online: whether @cpu is coming up or going down |
4492 | * |
4493 | * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and |
4494 | * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update pod affinity of |
4495 | * @wq accordingly. |
4496 | * |
4497 | * |
4498 | * If pod affinity can't be adjusted due to memory allocation failure, it falls |
4499 | * back to @wq->dfl_pwq which may not be optimal but is always correct. |
4500 | * |
4501 | * Note that when the last allowed CPU of a pod goes offline for a workqueue |
4502 | * with a cpumask spanning multiple pods, the workers which were already |
4503 | * executing the work items for the workqueue will lose their CPU affinity and |
4504 | * may execute on any CPU. This is similar to how per-cpu workqueues behave on |
4505 | * CPU_DOWN. If a workqueue user wants strict affinity, it's the user's |
4506 | * responsibility to flush the work item from CPU_DOWN_PREPARE. |
4507 | */ |
4508 | static void wq_update_pod(struct workqueue_struct *wq, int cpu, |
4509 | int hotplug_cpu, bool online) |
4510 | { |
4511 | int off_cpu = online ? -1 : hotplug_cpu; |
4512 | struct pool_workqueue *old_pwq = NULL, *pwq; |
4513 | struct workqueue_attrs *target_attrs; |
4514 | |
4515 | lockdep_assert_held(&wq_pool_mutex); |
4516 | |
4517 | if (!(wq->flags & WQ_UNBOUND) || wq->unbound_attrs->ordered) |
4518 | return; |
4519 | |
4520 | /* |
4521 | * We don't wanna alloc/free wq_attrs for each wq for each CPU. |
4522 | * Let's use a preallocated one. The following buf is protected by |
4523 | * CPU hotplug exclusion. |
4524 | */ |
4525 | target_attrs = wq_update_pod_attrs_buf; |
4526 | |
4527 | copy_workqueue_attrs(to: target_attrs, from: wq->unbound_attrs); |
4528 | wqattrs_actualize_cpumask(attrs: target_attrs, unbound_cpumask: wq_unbound_cpumask); |
4529 | |
4530 | /* nothing to do if the target cpumask matches the current pwq */ |
4531 | wq_calc_pod_cpumask(attrs: target_attrs, cpu, cpu_going_down: off_cpu); |
4532 | pwq = rcu_dereference_protected(*per_cpu_ptr(wq->cpu_pwq, cpu), |
4533 | lockdep_is_held(&wq_pool_mutex)); |
4534 | if (wqattrs_equal(a: target_attrs, b: pwq->pool->attrs)) |
4535 | return; |
4536 | |
4537 | /* create a new pwq */ |
4538 | pwq = alloc_unbound_pwq(wq, attrs: target_attrs); |
4539 | if (!pwq) { |
4540 | pr_warn("workqueue: allocation failed while updating CPU pod affinity of \"%s\"\n" , |
4541 | wq->name); |
4542 | goto use_dfl_pwq; |
4543 | } |
4544 | |
4545 | /* Install the new pwq. */ |
4546 | mutex_lock(&wq->mutex); |
4547 | old_pwq = install_unbound_pwq(wq, cpu, pwq); |
4548 | goto out_unlock; |
4549 | |
4550 | use_dfl_pwq: |
4551 | mutex_lock(&wq->mutex); |
4552 | raw_spin_lock_irq(&wq->dfl_pwq->pool->lock); |
4553 | get_pwq(pwq: wq->dfl_pwq); |
4554 | raw_spin_unlock_irq(&wq->dfl_pwq->pool->lock); |
4555 | old_pwq = install_unbound_pwq(wq, cpu, pwq: wq->dfl_pwq); |
4556 | out_unlock: |
4557 | mutex_unlock(lock: &wq->mutex); |
4558 | put_pwq_unlocked(pwq: old_pwq); |
4559 | } |
4560 | |
4561 | static int alloc_and_link_pwqs(struct workqueue_struct *wq) |
4562 | { |
4563 | bool highpri = wq->flags & WQ_HIGHPRI; |
4564 | int cpu, ret; |
4565 | |
4566 | wq->cpu_pwq = alloc_percpu(struct pool_workqueue *); |
4567 | if (!wq->cpu_pwq) |
4568 | goto enomem; |
4569 | |
4570 | if (!(wq->flags & WQ_UNBOUND)) { |
4571 | for_each_possible_cpu(cpu) { |
4572 | struct pool_workqueue **pwq_p = |
4573 | per_cpu_ptr(wq->cpu_pwq, cpu); |
4574 | struct worker_pool *pool = |
4575 | &(per_cpu_ptr(cpu_worker_pools, cpu)[highpri]); |
4576 | |
4577 | *pwq_p = kmem_cache_alloc_node(s: pwq_cache, GFP_KERNEL, |
4578 | node: pool->node); |
4579 | if (!*pwq_p) |
4580 | goto enomem; |
4581 | |
4582 | init_pwq(pwq: *pwq_p, wq, pool); |
4583 | |
4584 | mutex_lock(&wq->mutex); |
4585 | link_pwq(pwq: *pwq_p); |
4586 | mutex_unlock(lock: &wq->mutex); |
4587 | } |
4588 | return 0; |
4589 | } |
4590 | |
4591 | cpus_read_lock(); |
4592 | if (wq->flags & __WQ_ORDERED) { |
4593 | ret = apply_workqueue_attrs(wq, attrs: ordered_wq_attrs[highpri]); |
4594 | /* there should only be single pwq for ordering guarantee */ |
4595 | WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || |
4596 | wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), |
4597 | "ordering guarantee broken for workqueue %s\n" , wq->name); |
4598 | } else { |
4599 | ret = apply_workqueue_attrs(wq, attrs: unbound_std_wq_attrs[highpri]); |
4600 | } |
4601 | cpus_read_unlock(); |
4602 | |
4603 | /* for unbound pwq, flush the pwq_release_worker ensures that the |
4604 | * pwq_release_workfn() completes before calling kfree(wq). |
4605 | */ |
4606 | if (ret) |
4607 | kthread_flush_worker(worker: pwq_release_worker); |
4608 | |
4609 | return ret; |
4610 | |
4611 | enomem: |
4612 | if (wq->cpu_pwq) { |
4613 | for_each_possible_cpu(cpu) { |
4614 | struct pool_workqueue *pwq = *per_cpu_ptr(wq->cpu_pwq, cpu); |
4615 | |
4616 | if (pwq) |
4617 | kmem_cache_free(s: pwq_cache, objp: pwq); |
4618 | } |
4619 | free_percpu(pdata: wq->cpu_pwq); |
4620 | wq->cpu_pwq = NULL; |
4621 | } |
4622 | return -ENOMEM; |
4623 | } |
4624 | |
4625 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
4626 | const char *name) |
4627 | { |
4628 | if (max_active < 1 || max_active > WQ_MAX_ACTIVE) |
4629 | pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n" , |
4630 | max_active, name, 1, WQ_MAX_ACTIVE); |
4631 | |
4632 | return clamp_val(max_active, 1, WQ_MAX_ACTIVE); |
4633 | } |
4634 | |
4635 | /* |
4636 | * Workqueues which may be used during memory reclaim should have a rescuer |
4637 | * to guarantee forward progress. |
4638 | */ |
4639 | static int init_rescuer(struct workqueue_struct *wq) |
4640 | { |
4641 | struct worker *rescuer; |
4642 | int ret; |
4643 | |
4644 | if (!(wq->flags & WQ_MEM_RECLAIM)) |
4645 | return 0; |
4646 | |
4647 | rescuer = alloc_worker(NUMA_NO_NODE); |
4648 | if (!rescuer) { |
4649 | pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n" , |
4650 | wq->name); |
4651 | return -ENOMEM; |
4652 | } |
4653 | |
4654 | rescuer->rescue_wq = wq; |
4655 | rescuer->task = kthread_create(rescuer_thread, rescuer, "kworker/R-%s" , wq->name); |
4656 | if (IS_ERR(ptr: rescuer->task)) { |
4657 | ret = PTR_ERR(ptr: rescuer->task); |
4658 | pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe" , |
4659 | wq->name, ERR_PTR(ret)); |
4660 | kfree(objp: rescuer); |
4661 | return ret; |
4662 | } |
4663 | |
4664 | wq->rescuer = rescuer; |
4665 | kthread_bind_mask(k: rescuer->task, cpu_possible_mask); |
4666 | wake_up_process(tsk: rescuer->task); |
4667 | |
4668 | return 0; |
4669 | } |
4670 | |
4671 | __printf(1, 4) |
4672 | struct workqueue_struct *alloc_workqueue(const char *fmt, |
4673 | unsigned int flags, |
4674 | int max_active, ...) |
4675 | { |
4676 | va_list args; |
4677 | struct workqueue_struct *wq; |
4678 | struct pool_workqueue *pwq; |
4679 | |
4680 | /* |
4681 | * Unbound && max_active == 1 used to imply ordered, which is no longer |
4682 | * the case on many machines due to per-pod pools. While |
4683 | * alloc_ordered_workqueue() is the right way to create an ordered |
4684 | * workqueue, keep the previous behavior to avoid subtle breakages. |
4685 | */ |
4686 | if ((flags & WQ_UNBOUND) && max_active == 1) |
4687 | flags |= __WQ_ORDERED; |
4688 | |
4689 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ |
4690 | if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) |
4691 | flags |= WQ_UNBOUND; |
4692 | |
4693 | /* allocate wq and format name */ |
4694 | wq = kzalloc(size: sizeof(*wq), GFP_KERNEL); |
4695 | if (!wq) |
4696 | return NULL; |
4697 | |
4698 | if (flags & WQ_UNBOUND) { |
4699 | wq->unbound_attrs = alloc_workqueue_attrs(); |
4700 | if (!wq->unbound_attrs) |
4701 | goto err_free_wq; |
4702 | } |
4703 | |
4704 | va_start(args, max_active); |
4705 | vsnprintf(buf: wq->name, size: sizeof(wq->name), fmt, args); |
4706 | va_end(args); |
4707 | |
4708 | max_active = max_active ?: WQ_DFL_ACTIVE; |
4709 | max_active = wq_clamp_max_active(max_active, flags, name: wq->name); |
4710 | |
4711 | /* init wq */ |
4712 | wq->flags = flags; |
4713 | wq->saved_max_active = max_active; |
4714 | mutex_init(&wq->mutex); |
4715 | atomic_set(v: &wq->nr_pwqs_to_flush, i: 0); |
4716 | INIT_LIST_HEAD(list: &wq->pwqs); |
4717 | INIT_LIST_HEAD(list: &wq->flusher_queue); |
4718 | INIT_LIST_HEAD(list: &wq->flusher_overflow); |
4719 | INIT_LIST_HEAD(list: &wq->maydays); |
4720 | |
4721 | wq_init_lockdep(wq); |
4722 | INIT_LIST_HEAD(list: &wq->list); |
4723 | |
4724 | if (alloc_and_link_pwqs(wq) < 0) |
4725 | goto err_unreg_lockdep; |
4726 | |
4727 | if (wq_online && init_rescuer(wq) < 0) |
4728 | goto err_destroy; |
4729 | |
4730 | if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) |
4731 | goto err_destroy; |
4732 | |
4733 | /* |
4734 | * wq_pool_mutex protects global freeze state and workqueues list. |
4735 | * Grab it, adjust max_active and add the new @wq to workqueues |
4736 | * list. |
4737 | */ |
4738 | mutex_lock(&wq_pool_mutex); |
4739 | |
4740 | mutex_lock(&wq->mutex); |
4741 | for_each_pwq(pwq, wq) |
4742 | pwq_adjust_max_active(pwq); |
4743 | mutex_unlock(lock: &wq->mutex); |
4744 | |
4745 | list_add_tail_rcu(new: &wq->list, head: &workqueues); |
4746 | |
4747 | mutex_unlock(lock: &wq_pool_mutex); |
4748 | |
4749 | return wq; |
4750 | |
4751 | err_unreg_lockdep: |
4752 | wq_unregister_lockdep(wq); |
4753 | wq_free_lockdep(wq); |
4754 | err_free_wq: |
4755 | free_workqueue_attrs(attrs: wq->unbound_attrs); |
4756 | kfree(objp: wq); |
4757 | return NULL; |
4758 | err_destroy: |
4759 | destroy_workqueue(wq); |
4760 | return NULL; |
4761 | } |
4762 | EXPORT_SYMBOL_GPL(alloc_workqueue); |
4763 | |
4764 | static bool pwq_busy(struct pool_workqueue *pwq) |
4765 | { |
4766 | int i; |
4767 | |
4768 | for (i = 0; i < WORK_NR_COLORS; i++) |
4769 | if (pwq->nr_in_flight[i]) |
4770 | return true; |
4771 | |
4772 | if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1)) |
4773 | return true; |
4774 | if (pwq->nr_active || !list_empty(head: &pwq->inactive_works)) |
4775 | return true; |
4776 | |
4777 | return false; |
4778 | } |
4779 | |
4780 | /** |
4781 | * destroy_workqueue - safely terminate a workqueue |
4782 | * @wq: target workqueue |
4783 | * |
4784 | * Safely destroy a workqueue. All work currently pending will be done first. |
4785 | */ |
4786 | void destroy_workqueue(struct workqueue_struct *wq) |
4787 | { |
4788 | struct pool_workqueue *pwq; |
4789 | int cpu; |
4790 | |
4791 | /* |
4792 | * Remove it from sysfs first so that sanity check failure doesn't |
4793 | * lead to sysfs name conflicts. |
4794 | */ |
4795 | workqueue_sysfs_unregister(wq); |
4796 | |
4797 | /* mark the workqueue destruction is in progress */ |
4798 | mutex_lock(&wq->mutex); |
4799 | wq->flags |= __WQ_DESTROYING; |
4800 | mutex_unlock(lock: &wq->mutex); |
4801 | |
4802 | /* drain it before proceeding with destruction */ |
4803 | drain_workqueue(wq); |
4804 | |
4805 | /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ |
4806 | if (wq->rescuer) { |
4807 | struct worker *rescuer = wq->rescuer; |
4808 | |
4809 | /* this prevents new queueing */ |
4810 | raw_spin_lock_irq(&wq_mayday_lock); |
4811 | wq->rescuer = NULL; |
4812 | raw_spin_unlock_irq(&wq_mayday_lock); |
4813 | |
4814 | /* rescuer will empty maydays list before exiting */ |
4815 | kthread_stop(k: rescuer->task); |
4816 | kfree(objp: rescuer); |
4817 | } |
4818 | |
4819 | /* |
4820 | * Sanity checks - grab all the locks so that we wait for all |
4821 | * in-flight operations which may do put_pwq(). |
4822 | */ |
4823 | mutex_lock(&wq_pool_mutex); |
4824 | mutex_lock(&wq->mutex); |
4825 | for_each_pwq(pwq, wq) { |
4826 | raw_spin_lock_irq(&pwq->pool->lock); |
4827 | if (WARN_ON(pwq_busy(pwq))) { |
4828 | pr_warn("%s: %s has the following busy pwq\n" , |
4829 | __func__, wq->name); |
4830 | show_pwq(pwq); |
4831 | raw_spin_unlock_irq(&pwq->pool->lock); |
4832 | mutex_unlock(lock: &wq->mutex); |
4833 | mutex_unlock(lock: &wq_pool_mutex); |
4834 | show_one_workqueue(wq); |
4835 | return; |
4836 | } |
4837 | raw_spin_unlock_irq(&pwq->pool->lock); |
4838 | } |
4839 | mutex_unlock(lock: &wq->mutex); |
4840 | |
4841 | /* |
4842 | * wq list is used to freeze wq, remove from list after |
4843 | * flushing is complete in case freeze races us. |
4844 | */ |
4845 | list_del_rcu(entry: &wq->list); |
4846 | mutex_unlock(lock: &wq_pool_mutex); |
4847 | |
4848 | /* |
4849 | * We're the sole accessor of @wq. Directly access cpu_pwq and dfl_pwq |
4850 | * to put the base refs. @wq will be auto-destroyed from the last |
4851 | * pwq_put. RCU read lock prevents @wq from going away from under us. |
4852 | */ |
4853 | rcu_read_lock(); |
4854 | |
4855 | for_each_possible_cpu(cpu) { |
4856 | pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu)); |
4857 | RCU_INIT_POINTER(*per_cpu_ptr(wq->cpu_pwq, cpu), NULL); |
4858 | put_pwq_unlocked(pwq); |
4859 | } |
4860 | |
4861 | put_pwq_unlocked(pwq: wq->dfl_pwq); |
4862 | wq->dfl_pwq = NULL; |
4863 | |
4864 | rcu_read_unlock(); |
4865 | } |
4866 | EXPORT_SYMBOL_GPL(destroy_workqueue); |
4867 | |
4868 | /** |
4869 | * workqueue_set_max_active - adjust max_active of a workqueue |
4870 | * @wq: target workqueue |
4871 | * @max_active: new max_active value. |
4872 | * |
4873 | * Set max_active of @wq to @max_active. |
4874 | * |
4875 | * CONTEXT: |
4876 | * Don't call from IRQ context. |
4877 | */ |
4878 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) |
4879 | { |
4880 | struct pool_workqueue *pwq; |
4881 | |
4882 | /* disallow meddling with max_active for ordered workqueues */ |
4883 | if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) |
4884 | return; |
4885 | |
4886 | max_active = wq_clamp_max_active(max_active, flags: wq->flags, name: wq->name); |
4887 | |
4888 | mutex_lock(&wq->mutex); |
4889 | |
4890 | wq->flags &= ~__WQ_ORDERED; |
4891 | wq->saved_max_active = max_active; |
4892 | |
4893 | for_each_pwq(pwq, wq) |
4894 | pwq_adjust_max_active(pwq); |
4895 | |
4896 | mutex_unlock(lock: &wq->mutex); |
4897 | } |
4898 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
4899 | |
4900 | /** |
4901 | * current_work - retrieve %current task's work struct |
4902 | * |
4903 | * Determine if %current task is a workqueue worker and what it's working on. |
4904 | * Useful to find out the context that the %current task is running in. |
4905 | * |
4906 | * Return: work struct if %current task is a workqueue worker, %NULL otherwise. |
4907 | */ |
4908 | struct work_struct *current_work(void) |
4909 | { |
4910 | struct worker *worker = current_wq_worker(); |
4911 | |
4912 | return worker ? worker->current_work : NULL; |
4913 | } |
4914 | EXPORT_SYMBOL(current_work); |
4915 | |
4916 | /** |
4917 | * current_is_workqueue_rescuer - is %current workqueue rescuer? |
4918 | * |
4919 | * Determine whether %current is a workqueue rescuer. Can be used from |
4920 | * work functions to determine whether it's being run off the rescuer task. |
4921 | * |
4922 | * Return: %true if %current is a workqueue rescuer. %false otherwise. |
4923 | */ |
4924 | bool current_is_workqueue_rescuer(void) |
4925 | { |
4926 | struct worker *worker = current_wq_worker(); |
4927 | |
4928 | return worker && worker->rescue_wq; |
4929 | } |
4930 | |
4931 | /** |
4932 | * workqueue_congested - test whether a workqueue is congested |
4933 | * @cpu: CPU in question |
4934 | * @wq: target workqueue |
4935 | * |
4936 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
4937 | * no synchronization around this function and the test result is |
4938 | * unreliable and only useful as advisory hints or for debugging. |
4939 | * |
4940 | * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. |
4941 | * |
4942 | * With the exception of ordered workqueues, all workqueues have per-cpu |
4943 | * pool_workqueues, each with its own congested state. A workqueue being |
4944 | * congested on one CPU doesn't mean that the workqueue is contested on any |
4945 | * other CPUs. |
4946 | * |
4947 | * Return: |
4948 | * %true if congested, %false otherwise. |
4949 | */ |
4950 | bool workqueue_congested(int cpu, struct workqueue_struct *wq) |
4951 | { |
4952 | struct pool_workqueue *pwq; |
4953 | bool ret; |
4954 | |
4955 | rcu_read_lock(); |
4956 | preempt_disable(); |
4957 | |
4958 | if (cpu == WORK_CPU_UNBOUND) |
4959 | cpu = smp_processor_id(); |
4960 | |
4961 | pwq = *per_cpu_ptr(wq->cpu_pwq, cpu); |
4962 | ret = !list_empty(head: &pwq->inactive_works); |
4963 | |
4964 | preempt_enable(); |
4965 | rcu_read_unlock(); |
4966 | |
4967 | return ret; |
4968 | } |
4969 | EXPORT_SYMBOL_GPL(workqueue_congested); |
4970 | |
4971 | /** |
4972 | * work_busy - test whether a work is currently pending or running |
4973 | * @work: the work to be tested |
4974 | * |
4975 | * Test whether @work is currently pending or running. There is no |
4976 | * synchronization around this function and the test result is |
4977 | * unreliable and only useful as advisory hints or for debugging. |
4978 | * |
4979 | * Return: |
4980 | * OR'd bitmask of WORK_BUSY_* bits. |
4981 | */ |
4982 | unsigned int work_busy(struct work_struct *work) |
4983 | { |
4984 | struct worker_pool *pool; |
4985 | unsigned long flags; |
4986 | unsigned int ret = 0; |
4987 | |
4988 | if (work_pending(work)) |
4989 | ret |= WORK_BUSY_PENDING; |
4990 | |
4991 | rcu_read_lock(); |
4992 | pool = get_work_pool(work); |
4993 | if (pool) { |
4994 | raw_spin_lock_irqsave(&pool->lock, flags); |
4995 | if (find_worker_executing_work(pool, work)) |
4996 | ret |= WORK_BUSY_RUNNING; |
4997 | raw_spin_unlock_irqrestore(&pool->lock, flags); |
4998 | } |
4999 | rcu_read_unlock(); |
5000 | |
5001 | return ret; |
5002 | } |
5003 | EXPORT_SYMBOL_GPL(work_busy); |
5004 | |
5005 | /** |
5006 | * set_worker_desc - set description for the current work item |
5007 | * @fmt: printf-style format string |
5008 | * @...: arguments for the format string |
5009 | * |
5010 | * This function can be called by a running work function to describe what |
5011 | * the work item is about. If the worker task gets dumped, this |
5012 | * information will be printed out together to help debugging. The |
5013 | * description can be at most WORKER_DESC_LEN including the trailing '\0'. |
5014 | */ |
5015 | void set_worker_desc(const char *fmt, ...) |
5016 | { |
5017 | struct worker *worker = current_wq_worker(); |
5018 | va_list args; |
5019 | |
5020 | if (worker) { |
5021 | va_start(args, fmt); |
5022 | vsnprintf(buf: worker->desc, size: sizeof(worker->desc), fmt, args); |
5023 | va_end(args); |
5024 | } |
5025 | } |
5026 | EXPORT_SYMBOL_GPL(set_worker_desc); |
5027 | |
5028 | /** |
5029 | * print_worker_info - print out worker information and description |
5030 | * @log_lvl: the log level to use when printing |
5031 | * @task: target task |
5032 | * |
5033 | * If @task is a worker and currently executing a work item, print out the |
5034 | * name of the workqueue being serviced and worker description set with |
5035 | * set_worker_desc() by the currently executing work item. |
5036 | * |
5037 | * This function can be safely called on any task as long as the |
5038 | * task_struct itself is accessible. While safe, this function isn't |
5039 | * synchronized and may print out mixups or garbages of limited length. |
5040 | */ |
5041 | void print_worker_info(const char *log_lvl, struct task_struct *task) |
5042 | { |
5043 | work_func_t *fn = NULL; |
5044 | char name[WQ_NAME_LEN] = { }; |
5045 | char desc[WORKER_DESC_LEN] = { }; |
5046 | struct pool_workqueue *pwq = NULL; |
5047 | struct workqueue_struct *wq = NULL; |
5048 | struct worker *worker; |
5049 | |
5050 | if (!(task->flags & PF_WQ_WORKER)) |
5051 | return; |
5052 | |
5053 | /* |
5054 | * This function is called without any synchronization and @task |
5055 | * could be in any state. Be careful with dereferences. |
5056 | */ |
5057 | worker = kthread_probe_data(k: task); |
5058 | |
5059 | /* |
5060 | * Carefully copy the associated workqueue's workfn, name and desc. |
5061 | * Keep the original last '\0' in case the original is garbage. |
5062 | */ |
5063 | copy_from_kernel_nofault(dst: &fn, src: &worker->current_func, size: sizeof(fn)); |
5064 | copy_from_kernel_nofault(dst: &pwq, src: &worker->current_pwq, size: sizeof(pwq)); |
5065 | copy_from_kernel_nofault(dst: &wq, src: &pwq->wq, size: sizeof(wq)); |
5066 | copy_from_kernel_nofault(dst: name, src: wq->name, size: sizeof(name) - 1); |
5067 | copy_from_kernel_nofault(dst: desc, src: worker->desc, size: sizeof(desc) - 1); |
5068 | |
5069 | if (fn || name[0] || desc[0]) { |
5070 | printk("%sWorkqueue: %s %ps" , log_lvl, name, fn); |
5071 | if (strcmp(name, desc)) |
5072 | pr_cont(" (%s)" , desc); |
5073 | pr_cont("\n" ); |
5074 | } |
5075 | } |
5076 | |
5077 | static void pr_cont_pool_info(struct worker_pool *pool) |
5078 | { |
5079 | pr_cont(" cpus=%*pbl" , nr_cpumask_bits, pool->attrs->cpumask); |
5080 | if (pool->node != NUMA_NO_NODE) |
5081 | pr_cont(" node=%d" , pool->node); |
5082 | pr_cont(" flags=0x%x nice=%d" , pool->flags, pool->attrs->nice); |
5083 | } |
5084 | |
5085 | struct pr_cont_work_struct { |
5086 | bool comma; |
5087 | work_func_t func; |
5088 | long ctr; |
5089 | }; |
5090 | |
5091 | static void pr_cont_work_flush(bool comma, work_func_t func, struct pr_cont_work_struct *pcwsp) |
5092 | { |
5093 | if (!pcwsp->ctr) |
5094 | goto out_record; |
5095 | if (func == pcwsp->func) { |
5096 | pcwsp->ctr++; |
5097 | return; |
5098 | } |
5099 | if (pcwsp->ctr == 1) |
5100 | pr_cont("%s %ps" , pcwsp->comma ? "," : "" , pcwsp->func); |
5101 | else |
5102 | pr_cont("%s %ld*%ps" , pcwsp->comma ? "," : "" , pcwsp->ctr, pcwsp->func); |
5103 | pcwsp->ctr = 0; |
5104 | out_record: |
5105 | if ((long)func == -1L) |
5106 | return; |
5107 | pcwsp->comma = comma; |
5108 | pcwsp->func = func; |
5109 | pcwsp->ctr = 1; |
5110 | } |
5111 | |
5112 | static void pr_cont_work(bool comma, struct work_struct *work, struct pr_cont_work_struct *pcwsp) |
5113 | { |
5114 | if (work->func == wq_barrier_func) { |
5115 | struct wq_barrier *barr; |
5116 | |
5117 | barr = container_of(work, struct wq_barrier, work); |
5118 | |
5119 | pr_cont_work_flush(comma, func: (work_func_t)-1, pcwsp); |
5120 | pr_cont("%s BAR(%d)" , comma ? "," : "" , |
5121 | task_pid_nr(barr->task)); |
5122 | } else { |
5123 | if (!comma) |
5124 | pr_cont_work_flush(comma, func: (work_func_t)-1, pcwsp); |
5125 | pr_cont_work_flush(comma, func: work->func, pcwsp); |
5126 | } |
5127 | } |
5128 | |
5129 | static void show_pwq(struct pool_workqueue *pwq) |
5130 | { |
5131 | struct pr_cont_work_struct pcws = { .ctr = 0, }; |
5132 | struct worker_pool *pool = pwq->pool; |
5133 | struct work_struct *work; |
5134 | struct worker *worker; |
5135 | bool has_in_flight = false, has_pending = false; |
5136 | int bkt; |
5137 | |
5138 | pr_info(" pwq %d:" , pool->id); |
5139 | pr_cont_pool_info(pool); |
5140 | |
5141 | pr_cont(" active=%d/%d refcnt=%d%s\n" , |
5142 | pwq->nr_active, pwq->max_active, pwq->refcnt, |
5143 | !list_empty(&pwq->mayday_node) ? " MAYDAY" : "" ); |
5144 | |
5145 | hash_for_each(pool->busy_hash, bkt, worker, hentry) { |
5146 | if (worker->current_pwq == pwq) { |
5147 | has_in_flight = true; |
5148 | break; |
5149 | } |
5150 | } |
5151 | if (has_in_flight) { |
5152 | bool comma = false; |
5153 | |
5154 | pr_info(" in-flight:" ); |
5155 | hash_for_each(pool->busy_hash, bkt, worker, hentry) { |
5156 | if (worker->current_pwq != pwq) |
5157 | continue; |
5158 | |
5159 | pr_cont("%s %d%s:%ps" , comma ? "," : "" , |
5160 | task_pid_nr(worker->task), |
5161 | worker->rescue_wq ? "(RESCUER)" : "" , |
5162 | worker->current_func); |
5163 | list_for_each_entry(work, &worker->scheduled, entry) |
5164 | pr_cont_work(comma: false, work, pcwsp: &pcws); |
5165 | pr_cont_work_flush(comma, func: (work_func_t)-1L, pcwsp: &pcws); |
5166 | comma = true; |
5167 | } |
5168 | pr_cont("\n" ); |
5169 | } |
5170 | |
5171 | list_for_each_entry(work, &pool->worklist, entry) { |
5172 | if (get_work_pwq(work) == pwq) { |
5173 | has_pending = true; |
5174 | break; |
5175 | } |
5176 | } |
5177 | if (has_pending) { |
5178 | bool comma = false; |
5179 | |
5180 | pr_info(" pending:" ); |
5181 | list_for_each_entry(work, &pool->worklist, entry) { |
5182 | if (get_work_pwq(work) != pwq) |
5183 | continue; |
5184 | |
5185 | pr_cont_work(comma, work, pcwsp: &pcws); |
5186 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); |
5187 | } |
5188 | pr_cont_work_flush(comma, func: (work_func_t)-1L, pcwsp: &pcws); |
5189 | pr_cont("\n" ); |
5190 | } |
5191 | |
5192 | if (!list_empty(head: &pwq->inactive_works)) { |
5193 | bool comma = false; |
5194 | |
5195 | pr_info(" inactive:" ); |
5196 | list_for_each_entry(work, &pwq->inactive_works, entry) { |
5197 | pr_cont_work(comma, work, pcwsp: &pcws); |
5198 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); |
5199 | } |
5200 | pr_cont_work_flush(comma, func: (work_func_t)-1L, pcwsp: &pcws); |
5201 | pr_cont("\n" ); |
5202 | } |
5203 | } |
5204 | |
5205 | /** |
5206 | * show_one_workqueue - dump state of specified workqueue |
5207 | * @wq: workqueue whose state will be printed |
5208 | */ |
5209 | void show_one_workqueue(struct workqueue_struct *wq) |
5210 | { |
5211 | struct pool_workqueue *pwq; |
5212 | bool idle = true; |
5213 | unsigned long flags; |
5214 | |
5215 | for_each_pwq(pwq, wq) { |
5216 | if (pwq->nr_active || !list_empty(head: &pwq->inactive_works)) { |
5217 | idle = false; |
5218 | break; |
5219 | } |
5220 | } |
5221 | if (idle) /* Nothing to print for idle workqueue */ |
5222 | return; |
5223 | |
5224 | pr_info("workqueue %s: flags=0x%x\n" , wq->name, wq->flags); |
5225 | |
5226 | for_each_pwq(pwq, wq) { |
5227 | raw_spin_lock_irqsave(&pwq->pool->lock, flags); |
5228 | if (pwq->nr_active || !list_empty(head: &pwq->inactive_works)) { |
5229 | /* |
5230 | * Defer printing to avoid deadlocks in console |
5231 | * drivers that queue work while holding locks |
5232 | * also taken in their write paths. |
5233 | */ |
5234 | printk_deferred_enter(); |
5235 | show_pwq(pwq); |
5236 | printk_deferred_exit(); |
5237 | } |
5238 | raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); |
5239 | /* |
5240 | * We could be printing a lot from atomic context, e.g. |
5241 | * sysrq-t -> show_all_workqueues(). Avoid triggering |
5242 | * hard lockup. |
5243 | */ |
5244 | touch_nmi_watchdog(); |
5245 | } |
5246 | |
5247 | } |
5248 | |
5249 | /** |
5250 | * show_one_worker_pool - dump state of specified worker pool |
5251 | * @pool: worker pool whose state will be printed |
5252 | */ |
5253 | static void show_one_worker_pool(struct worker_pool *pool) |
5254 | { |
5255 | struct worker *worker; |
5256 | bool first = true; |
5257 | unsigned long flags; |
5258 | unsigned long hung = 0; |
5259 | |
5260 | raw_spin_lock_irqsave(&pool->lock, flags); |
5261 | if (pool->nr_workers == pool->nr_idle) |
5262 | goto next_pool; |
5263 | |
5264 | /* How long the first pending work is waiting for a worker. */ |
5265 | if (!list_empty(head: &pool->worklist)) |
5266 | hung = jiffies_to_msecs(j: jiffies - pool->watchdog_ts) / 1000; |
5267 | |
5268 | /* |
5269 | * Defer printing to avoid deadlocks in console drivers that |
5270 | * queue work while holding locks also taken in their write |
5271 | * paths. |
5272 | */ |
5273 | printk_deferred_enter(); |
5274 | pr_info("pool %d:" , pool->id); |
5275 | pr_cont_pool_info(pool); |
5276 | pr_cont(" hung=%lus workers=%d" , hung, pool->nr_workers); |
5277 | if (pool->manager) |
5278 | pr_cont(" manager: %d" , |
5279 | task_pid_nr(pool->manager->task)); |
5280 | list_for_each_entry(worker, &pool->idle_list, entry) { |
5281 | pr_cont(" %s%d" , first ? "idle: " : "" , |
5282 | task_pid_nr(worker->task)); |
5283 | first = false; |
5284 | } |
5285 | pr_cont("\n" ); |
5286 | printk_deferred_exit(); |
5287 | next_pool: |
5288 | raw_spin_unlock_irqrestore(&pool->lock, flags); |
5289 | /* |
5290 | * We could be printing a lot from atomic context, e.g. |
5291 | * sysrq-t -> show_all_workqueues(). Avoid triggering |
5292 | * hard lockup. |
5293 | */ |
5294 | touch_nmi_watchdog(); |
5295 | |
5296 | } |
5297 | |
5298 | /** |
5299 | * show_all_workqueues - dump workqueue state |
5300 | * |
5301 | * Called from a sysrq handler and prints out all busy workqueues and pools. |
5302 | */ |
5303 | void show_all_workqueues(void) |
5304 | { |
5305 | struct workqueue_struct *wq; |
5306 | struct worker_pool *pool; |
5307 | int pi; |
5308 | |
5309 | rcu_read_lock(); |
5310 | |
5311 | pr_info("Showing busy workqueues and worker pools:\n" ); |
5312 | |
5313 | list_for_each_entry_rcu(wq, &workqueues, list) |
5314 | show_one_workqueue(wq); |
5315 | |
5316 | for_each_pool(pool, pi) |
5317 | show_one_worker_pool(pool); |
5318 | |
5319 | rcu_read_unlock(); |
5320 | } |
5321 | |
5322 | /** |
5323 | * show_freezable_workqueues - dump freezable workqueue state |
5324 | * |
5325 | * Called from try_to_freeze_tasks() and prints out all freezable workqueues |
5326 | * still busy. |
5327 | */ |
5328 | void show_freezable_workqueues(void) |
5329 | { |
5330 | struct workqueue_struct *wq; |
5331 | |
5332 | rcu_read_lock(); |
5333 | |
5334 | pr_info("Showing freezable workqueues that are still busy:\n" ); |
5335 | |
5336 | list_for_each_entry_rcu(wq, &workqueues, list) { |
5337 | if (!(wq->flags & WQ_FREEZABLE)) |
5338 | continue; |
5339 | show_one_workqueue(wq); |
5340 | } |
5341 | |
5342 | rcu_read_unlock(); |
5343 | } |
5344 | |
5345 | /* used to show worker information through /proc/PID/{comm,stat,status} */ |
5346 | void wq_worker_comm(char *buf, size_t size, struct task_struct *task) |
5347 | { |
5348 | int off; |
5349 | |
5350 | /* always show the actual comm */ |
5351 | off = strscpy(p: buf, q: task->comm, size); |
5352 | if (off < 0) |
5353 | return; |
5354 | |
5355 | /* stabilize PF_WQ_WORKER and worker pool association */ |
5356 | mutex_lock(&wq_pool_attach_mutex); |
5357 | |
5358 | if (task->flags & PF_WQ_WORKER) { |
5359 | struct worker *worker = kthread_data(k: task); |
5360 | struct worker_pool *pool = worker->pool; |
5361 | |
5362 | if (pool) { |
5363 | raw_spin_lock_irq(&pool->lock); |
5364 | /* |
5365 | * ->desc tracks information (wq name or |
5366 | * set_worker_desc()) for the latest execution. If |
5367 | * current, prepend '+', otherwise '-'. |
5368 | */ |
5369 | if (worker->desc[0] != '\0') { |
5370 | if (worker->current_work) |
5371 | scnprintf(buf: buf + off, size: size - off, fmt: "+%s" , |
5372 | worker->desc); |
5373 | else |
5374 | scnprintf(buf: buf + off, size: size - off, fmt: "-%s" , |
5375 | worker->desc); |
5376 | } |
5377 | raw_spin_unlock_irq(&pool->lock); |
5378 | } |
5379 | } |
5380 | |
5381 | mutex_unlock(lock: &wq_pool_attach_mutex); |
5382 | } |
5383 | |
5384 | #ifdef CONFIG_SMP |
5385 | |
5386 | /* |
5387 | * CPU hotplug. |
5388 | * |
5389 | * There are two challenges in supporting CPU hotplug. Firstly, there |
5390 | * are a lot of assumptions on strong associations among work, pwq and |
5391 | * pool which make migrating pending and scheduled works very |
5392 | * difficult to implement without impacting hot paths. Secondly, |
5393 | * worker pools serve mix of short, long and very long running works making |
5394 | * blocked draining impractical. |
5395 | * |
5396 | * This is solved by allowing the pools to be disassociated from the CPU |
5397 | * running as an unbound one and allowing it to be reattached later if the |
5398 | * cpu comes back online. |
5399 | */ |
5400 | |
5401 | static void unbind_workers(int cpu) |
5402 | { |
5403 | struct worker_pool *pool; |
5404 | struct worker *worker; |
5405 | |
5406 | for_each_cpu_worker_pool(pool, cpu) { |
5407 | mutex_lock(&wq_pool_attach_mutex); |
5408 | raw_spin_lock_irq(&pool->lock); |
5409 | |
5410 | /* |
5411 | * We've blocked all attach/detach operations. Make all workers |
5412 | * unbound and set DISASSOCIATED. Before this, all workers |
5413 | * must be on the cpu. After this, they may become diasporas. |
5414 | * And the preemption disabled section in their sched callbacks |
5415 | * are guaranteed to see WORKER_UNBOUND since the code here |
5416 | * is on the same cpu. |
5417 | */ |
5418 | for_each_pool_worker(worker, pool) |
5419 | worker->flags |= WORKER_UNBOUND; |
5420 | |
5421 | pool->flags |= POOL_DISASSOCIATED; |
5422 | |
5423 | /* |
5424 | * The handling of nr_running in sched callbacks are disabled |
5425 | * now. Zap nr_running. After this, nr_running stays zero and |
5426 | * need_more_worker() and keep_working() are always true as |
5427 | * long as the worklist is not empty. This pool now behaves as |
5428 | * an unbound (in terms of concurrency management) pool which |
5429 | * are served by workers tied to the pool. |
5430 | */ |
5431 | pool->nr_running = 0; |
5432 | |
5433 | /* |
5434 | * With concurrency management just turned off, a busy |
5435 | * worker blocking could lead to lengthy stalls. Kick off |
5436 | * unbound chain execution of currently pending work items. |
5437 | */ |
5438 | kick_pool(pool); |
5439 | |
5440 | raw_spin_unlock_irq(&pool->lock); |
5441 | |
5442 | for_each_pool_worker(worker, pool) |
5443 | unbind_worker(worker); |
5444 | |
5445 | mutex_unlock(lock: &wq_pool_attach_mutex); |
5446 | } |
5447 | } |
5448 | |
5449 | /** |
5450 | * rebind_workers - rebind all workers of a pool to the associated CPU |
5451 | * @pool: pool of interest |
5452 | * |
5453 | * @pool->cpu is coming online. Rebind all workers to the CPU. |
5454 | */ |
5455 | static void rebind_workers(struct worker_pool *pool) |
5456 | { |
5457 | struct worker *worker; |
5458 | |
5459 | lockdep_assert_held(&wq_pool_attach_mutex); |
5460 | |
5461 | /* |
5462 | * Restore CPU affinity of all workers. As all idle workers should |
5463 | * be on the run-queue of the associated CPU before any local |
5464 | * wake-ups for concurrency management happen, restore CPU affinity |
5465 | * of all workers first and then clear UNBOUND. As we're called |
5466 | * from CPU_ONLINE, the following shouldn't fail. |
5467 | */ |
5468 | for_each_pool_worker(worker, pool) { |
5469 | kthread_set_per_cpu(k: worker->task, cpu: pool->cpu); |
5470 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, |
5471 | pool_allowed_cpus(pool)) < 0); |
5472 | } |
5473 | |
5474 | raw_spin_lock_irq(&pool->lock); |
5475 | |
5476 | pool->flags &= ~POOL_DISASSOCIATED; |
5477 | |
5478 | for_each_pool_worker(worker, pool) { |
5479 | unsigned int worker_flags = worker->flags; |
5480 | |
5481 | /* |
5482 | * We want to clear UNBOUND but can't directly call |
5483 | * worker_clr_flags() or adjust nr_running. Atomically |
5484 | * replace UNBOUND with another NOT_RUNNING flag REBOUND. |
5485 | * @worker will clear REBOUND using worker_clr_flags() when |
5486 | * it initiates the next execution cycle thus restoring |
5487 | * concurrency management. Note that when or whether |
5488 | * @worker clears REBOUND doesn't affect correctness. |
5489 | * |
5490 | * WRITE_ONCE() is necessary because @worker->flags may be |
5491 | * tested without holding any lock in |
5492 | * wq_worker_running(). Without it, NOT_RUNNING test may |
5493 | * fail incorrectly leading to premature concurrency |
5494 | * management operations. |
5495 | */ |
5496 | WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); |
5497 | worker_flags |= WORKER_REBOUND; |
5498 | worker_flags &= ~WORKER_UNBOUND; |
5499 | WRITE_ONCE(worker->flags, worker_flags); |
5500 | } |
5501 | |
5502 | raw_spin_unlock_irq(&pool->lock); |
5503 | } |
5504 | |
5505 | /** |
5506 | * restore_unbound_workers_cpumask - restore cpumask of unbound workers |
5507 | * @pool: unbound pool of interest |
5508 | * @cpu: the CPU which is coming up |
5509 | * |
5510 | * An unbound pool may end up with a cpumask which doesn't have any online |
5511 | * CPUs. When a worker of such pool get scheduled, the scheduler resets |
5512 | * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any |
5513 | * online CPU before, cpus_allowed of all its workers should be restored. |
5514 | */ |
5515 | static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) |
5516 | { |
5517 | static cpumask_t cpumask; |
5518 | struct worker *worker; |
5519 | |
5520 | lockdep_assert_held(&wq_pool_attach_mutex); |
5521 | |
5522 | /* is @cpu allowed for @pool? */ |
5523 | if (!cpumask_test_cpu(cpu, cpumask: pool->attrs->cpumask)) |
5524 | return; |
5525 | |
5526 | cpumask_and(dstp: &cpumask, src1p: pool->attrs->cpumask, cpu_online_mask); |
5527 | |
5528 | /* as we're called from CPU_ONLINE, the following shouldn't fail */ |
5529 | for_each_pool_worker(worker, pool) |
5530 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0); |
5531 | } |
5532 | |
5533 | int workqueue_prepare_cpu(unsigned int cpu) |
5534 | { |
5535 | struct worker_pool *pool; |
5536 | |
5537 | for_each_cpu_worker_pool(pool, cpu) { |
5538 | if (pool->nr_workers) |
5539 | continue; |
5540 | if (!create_worker(pool)) |
5541 | return -ENOMEM; |
5542 | } |
5543 | return 0; |
5544 | } |
5545 | |
5546 | int workqueue_online_cpu(unsigned int cpu) |
5547 | { |
5548 | struct worker_pool *pool; |
5549 | struct workqueue_struct *wq; |
5550 | int pi; |
5551 | |
5552 | mutex_lock(&wq_pool_mutex); |
5553 | |
5554 | for_each_pool(pool, pi) { |
5555 | mutex_lock(&wq_pool_attach_mutex); |
5556 | |
5557 | if (pool->cpu == cpu) |
5558 | rebind_workers(pool); |
5559 | else if (pool->cpu < 0) |
5560 | restore_unbound_workers_cpumask(pool, cpu); |
5561 | |
5562 | mutex_unlock(lock: &wq_pool_attach_mutex); |
5563 | } |
5564 | |
5565 | /* update pod affinity of unbound workqueues */ |
5566 | list_for_each_entry(wq, &workqueues, list) { |
5567 | struct workqueue_attrs *attrs = wq->unbound_attrs; |
5568 | |
5569 | if (attrs) { |
5570 | const struct wq_pod_type *pt = wqattrs_pod_type(attrs); |
5571 | int tcpu; |
5572 | |
5573 | for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) |
5574 | wq_update_pod(wq, cpu: tcpu, hotplug_cpu: cpu, online: true); |
5575 | } |
5576 | } |
5577 | |
5578 | mutex_unlock(lock: &wq_pool_mutex); |
5579 | return 0; |
5580 | } |
5581 | |
5582 | int workqueue_offline_cpu(unsigned int cpu) |
5583 | { |
5584 | struct workqueue_struct *wq; |
5585 | |
5586 | /* unbinding per-cpu workers should happen on the local CPU */ |
5587 | if (WARN_ON(cpu != smp_processor_id())) |
5588 | return -1; |
5589 | |
5590 | unbind_workers(cpu); |
5591 | |
5592 | /* update pod affinity of unbound workqueues */ |
5593 | mutex_lock(&wq_pool_mutex); |
5594 | list_for_each_entry(wq, &workqueues, list) { |
5595 | struct workqueue_attrs *attrs = wq->unbound_attrs; |
5596 | |
5597 | if (attrs) { |
5598 | const struct wq_pod_type *pt = wqattrs_pod_type(attrs); |
5599 | int tcpu; |
5600 | |
5601 | for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) |
5602 | wq_update_pod(wq, cpu: tcpu, hotplug_cpu: cpu, online: false); |
5603 | } |
5604 | } |
5605 | mutex_unlock(lock: &wq_pool_mutex); |
5606 | |
5607 | return 0; |
5608 | } |
5609 | |
5610 | struct work_for_cpu { |
5611 | struct work_struct work; |
5612 | long (*fn)(void *); |
5613 | void *arg; |
5614 | long ret; |
5615 | }; |
5616 | |
5617 | static void work_for_cpu_fn(struct work_struct *work) |
5618 | { |
5619 | struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); |
5620 | |
5621 | wfc->ret = wfc->fn(wfc->arg); |
5622 | } |
5623 | |
5624 | /** |
5625 | * work_on_cpu_key - run a function in thread context on a particular cpu |
5626 | * @cpu: the cpu to run on |
5627 | * @fn: the function to run |
5628 | * @arg: the function arg |
5629 | * @key: The lock class key for lock debugging purposes |
5630 | * |
5631 | * It is up to the caller to ensure that the cpu doesn't go offline. |
5632 | * The caller must not hold any locks which would prevent @fn from completing. |
5633 | * |
5634 | * Return: The value @fn returns. |
5635 | */ |
5636 | long work_on_cpu_key(int cpu, long (*fn)(void *), |
5637 | void *arg, struct lock_class_key *key) |
5638 | { |
5639 | struct work_for_cpu wfc = { .fn = fn, .arg = arg }; |
5640 | |
5641 | INIT_WORK_ONSTACK_KEY(&wfc.work, work_for_cpu_fn, key); |
5642 | schedule_work_on(cpu, work: &wfc.work); |
5643 | flush_work(&wfc.work); |
5644 | destroy_work_on_stack(&wfc.work); |
5645 | return wfc.ret; |
5646 | } |
5647 | EXPORT_SYMBOL_GPL(work_on_cpu_key); |
5648 | |
5649 | /** |
5650 | * work_on_cpu_safe_key - run a function in thread context on a particular cpu |
5651 | * @cpu: the cpu to run on |
5652 | * @fn: the function to run |
5653 | * @arg: the function argument |
5654 | * @key: The lock class key for lock debugging purposes |
5655 | * |
5656 | * Disables CPU hotplug and calls work_on_cpu(). The caller must not hold |
5657 | * any locks which would prevent @fn from completing. |
5658 | * |
5659 | * Return: The value @fn returns. |
5660 | */ |
5661 | long work_on_cpu_safe_key(int cpu, long (*fn)(void *), |
5662 | void *arg, struct lock_class_key *key) |
5663 | { |
5664 | long ret = -ENODEV; |
5665 | |
5666 | cpus_read_lock(); |
5667 | if (cpu_online(cpu)) |
5668 | ret = work_on_cpu_key(cpu, fn, arg, key); |
5669 | cpus_read_unlock(); |
5670 | return ret; |
5671 | } |
5672 | EXPORT_SYMBOL_GPL(work_on_cpu_safe_key); |
5673 | #endif /* CONFIG_SMP */ |
5674 | |
5675 | #ifdef CONFIG_FREEZER |
5676 | |
5677 | /** |
5678 | * freeze_workqueues_begin - begin freezing workqueues |
5679 | * |
5680 | * Start freezing workqueues. After this function returns, all freezable |
5681 | * workqueues will queue new works to their inactive_works list instead of |
5682 | * pool->worklist. |
5683 | * |
5684 | * CONTEXT: |
5685 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. |
5686 | */ |
5687 | void freeze_workqueues_begin(void) |
5688 | { |
5689 | struct workqueue_struct *wq; |
5690 | struct pool_workqueue *pwq; |
5691 | |
5692 | mutex_lock(&wq_pool_mutex); |
5693 | |
5694 | WARN_ON_ONCE(workqueue_freezing); |
5695 | workqueue_freezing = true; |
5696 | |
5697 | list_for_each_entry(wq, &workqueues, list) { |
5698 | mutex_lock(&wq->mutex); |
5699 | for_each_pwq(pwq, wq) |
5700 | pwq_adjust_max_active(pwq); |
5701 | mutex_unlock(lock: &wq->mutex); |
5702 | } |
5703 | |
5704 | mutex_unlock(lock: &wq_pool_mutex); |
5705 | } |
5706 | |
5707 | /** |
5708 | * freeze_workqueues_busy - are freezable workqueues still busy? |
5709 | * |
5710 | * Check whether freezing is complete. This function must be called |
5711 | * between freeze_workqueues_begin() and thaw_workqueues(). |
5712 | * |
5713 | * CONTEXT: |
5714 | * Grabs and releases wq_pool_mutex. |
5715 | * |
5716 | * Return: |
5717 | * %true if some freezable workqueues are still busy. %false if freezing |
5718 | * is complete. |
5719 | */ |
5720 | bool freeze_workqueues_busy(void) |
5721 | { |
5722 | bool busy = false; |
5723 | struct workqueue_struct *wq; |
5724 | struct pool_workqueue *pwq; |
5725 | |
5726 | mutex_lock(&wq_pool_mutex); |
5727 | |
5728 | WARN_ON_ONCE(!workqueue_freezing); |
5729 | |
5730 | list_for_each_entry(wq, &workqueues, list) { |
5731 | if (!(wq->flags & WQ_FREEZABLE)) |
5732 | continue; |
5733 | /* |
5734 | * nr_active is monotonically decreasing. It's safe |
5735 | * to peek without lock. |
5736 | */ |
5737 | rcu_read_lock(); |
5738 | for_each_pwq(pwq, wq) { |
5739 | WARN_ON_ONCE(pwq->nr_active < 0); |
5740 | if (pwq->nr_active) { |
5741 | busy = true; |
5742 | rcu_read_unlock(); |
5743 | goto out_unlock; |
5744 | } |
5745 | } |
5746 | rcu_read_unlock(); |
5747 | } |
5748 | out_unlock: |
5749 | mutex_unlock(lock: &wq_pool_mutex); |
5750 | return busy; |
5751 | } |
5752 | |
5753 | /** |
5754 | * thaw_workqueues - thaw workqueues |
5755 | * |
5756 | * Thaw workqueues. Normal queueing is restored and all collected |
5757 | * frozen works are transferred to their respective pool worklists. |
5758 | * |
5759 | * CONTEXT: |
5760 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. |
5761 | */ |
5762 | void thaw_workqueues(void) |
5763 | { |
5764 | struct workqueue_struct *wq; |
5765 | struct pool_workqueue *pwq; |
5766 | |
5767 | mutex_lock(&wq_pool_mutex); |
5768 | |
5769 | if (!workqueue_freezing) |
5770 | goto out_unlock; |
5771 | |
5772 | workqueue_freezing = false; |
5773 | |
5774 | /* restore max_active and repopulate worklist */ |
5775 | list_for_each_entry(wq, &workqueues, list) { |
5776 | mutex_lock(&wq->mutex); |
5777 | for_each_pwq(pwq, wq) |
5778 | pwq_adjust_max_active(pwq); |
5779 | mutex_unlock(lock: &wq->mutex); |
5780 | } |
5781 | |
5782 | out_unlock: |
5783 | mutex_unlock(lock: &wq_pool_mutex); |
5784 | } |
5785 | #endif /* CONFIG_FREEZER */ |
5786 | |
5787 | static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask) |
5788 | { |
5789 | LIST_HEAD(ctxs); |
5790 | int ret = 0; |
5791 | struct workqueue_struct *wq; |
5792 | struct apply_wqattrs_ctx *ctx, *n; |
5793 | |
5794 | lockdep_assert_held(&wq_pool_mutex); |
5795 | |
5796 | list_for_each_entry(wq, &workqueues, list) { |
5797 | if (!(wq->flags & WQ_UNBOUND)) |
5798 | continue; |
5799 | |
5800 | /* creating multiple pwqs breaks ordering guarantee */ |
5801 | if (!list_empty(head: &wq->pwqs)) { |
5802 | if (wq->flags & __WQ_ORDERED_EXPLICIT) |
5803 | continue; |
5804 | wq->flags &= ~__WQ_ORDERED; |
5805 | } |
5806 | |
5807 | ctx = apply_wqattrs_prepare(wq, attrs: wq->unbound_attrs, unbound_cpumask); |
5808 | if (IS_ERR(ptr: ctx)) { |
5809 | ret = PTR_ERR(ptr: ctx); |
5810 | break; |
5811 | } |
5812 | |
5813 | list_add_tail(new: &ctx->list, head: &ctxs); |
5814 | } |
5815 | |
5816 | list_for_each_entry_safe(ctx, n, &ctxs, list) { |
5817 | if (!ret) |
5818 | apply_wqattrs_commit(ctx); |
5819 | apply_wqattrs_cleanup(ctx); |
5820 | } |
5821 | |
5822 | if (!ret) { |
5823 | mutex_lock(&wq_pool_attach_mutex); |
5824 | cpumask_copy(dstp: wq_unbound_cpumask, srcp: unbound_cpumask); |
5825 | mutex_unlock(lock: &wq_pool_attach_mutex); |
5826 | } |
5827 | return ret; |
5828 | } |
5829 | |
5830 | /** |
5831 | * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask |
5832 | * @cpumask: the cpumask to set |
5833 | * |
5834 | * The low-level workqueues cpumask is a global cpumask that limits |
5835 | * the affinity of all unbound workqueues. This function check the @cpumask |
5836 | * and apply it to all unbound workqueues and updates all pwqs of them. |
5837 | * |
5838 | * Return: 0 - Success |
5839 | * -EINVAL - Invalid @cpumask |
5840 | * -ENOMEM - Failed to allocate memory for attrs or pwqs. |
5841 | */ |
5842 | int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) |
5843 | { |
5844 | int ret = -EINVAL; |
5845 | |
5846 | /* |
5847 | * Not excluding isolated cpus on purpose. |
5848 | * If the user wishes to include them, we allow that. |
5849 | */ |
5850 | cpumask_and(dstp: cpumask, src1p: cpumask, cpu_possible_mask); |
5851 | if (!cpumask_empty(srcp: cpumask)) { |
5852 | apply_wqattrs_lock(); |
5853 | if (cpumask_equal(src1p: cpumask, src2p: wq_unbound_cpumask)) { |
5854 | ret = 0; |
5855 | goto out_unlock; |
5856 | } |
5857 | |
5858 | ret = workqueue_apply_unbound_cpumask(unbound_cpumask: cpumask); |
5859 | |
5860 | out_unlock: |
5861 | apply_wqattrs_unlock(); |
5862 | } |
5863 | |
5864 | return ret; |
5865 | } |
5866 | |
5867 | static int parse_affn_scope(const char *val) |
5868 | { |
5869 | int i; |
5870 | |
5871 | for (i = 0; i < ARRAY_SIZE(wq_affn_names); i++) { |
5872 | if (!strncasecmp(s1: val, s2: wq_affn_names[i], strlen(wq_affn_names[i]))) |
5873 | return i; |
5874 | } |
5875 | return -EINVAL; |
5876 | } |
5877 | |
5878 | static int wq_affn_dfl_set(const char *val, const struct kernel_param *kp) |
5879 | { |
5880 | struct workqueue_struct *wq; |
5881 | int affn, cpu; |
5882 | |
5883 | affn = parse_affn_scope(val); |
5884 | if (affn < 0) |
5885 | return affn; |
5886 | if (affn == WQ_AFFN_DFL) |
5887 | return -EINVAL; |
5888 | |
5889 | cpus_read_lock(); |
5890 | mutex_lock(&wq_pool_mutex); |
5891 | |
5892 | wq_affn_dfl = affn; |
5893 | |
5894 | list_for_each_entry(wq, &workqueues, list) { |
5895 | for_each_online_cpu(cpu) { |
5896 | wq_update_pod(wq, cpu, hotplug_cpu: cpu, online: true); |
5897 | } |
5898 | } |
5899 | |
5900 | mutex_unlock(lock: &wq_pool_mutex); |
5901 | cpus_read_unlock(); |
5902 | |
5903 | return 0; |
5904 | } |
5905 | |
5906 | static int wq_affn_dfl_get(char *buffer, const struct kernel_param *kp) |
5907 | { |
5908 | return scnprintf(buf: buffer, PAGE_SIZE, fmt: "%s\n" , wq_affn_names[wq_affn_dfl]); |
5909 | } |
5910 | |
5911 | static const struct kernel_param_ops wq_affn_dfl_ops = { |
5912 | .set = wq_affn_dfl_set, |
5913 | .get = wq_affn_dfl_get, |
5914 | }; |
5915 | |
5916 | module_param_cb(default_affinity_scope, &wq_affn_dfl_ops, NULL, 0644); |
5917 | |
5918 | #ifdef CONFIG_SYSFS |
5919 | /* |
5920 | * Workqueues with WQ_SYSFS flag set is visible to userland via |
5921 | * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the |
5922 | * following attributes. |
5923 | * |
5924 | * per_cpu RO bool : whether the workqueue is per-cpu or unbound |
5925 | * max_active RW int : maximum number of in-flight work items |
5926 | * |
5927 | * Unbound workqueues have the following extra attributes. |
5928 | * |
5929 | * nice RW int : nice value of the workers |
5930 | * cpumask RW mask : bitmask of allowed CPUs for the workers |
5931 | * affinity_scope RW str : worker CPU affinity scope (cache, numa, none) |
5932 | * affinity_strict RW bool : worker CPU affinity is strict |
5933 | */ |
5934 | struct wq_device { |
5935 | struct workqueue_struct *wq; |
5936 | struct device dev; |
5937 | }; |
5938 | |
5939 | static struct workqueue_struct *dev_to_wq(struct device *dev) |
5940 | { |
5941 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); |
5942 | |
5943 | return wq_dev->wq; |
5944 | } |
5945 | |
5946 | static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, |
5947 | char *buf) |
5948 | { |
5949 | struct workqueue_struct *wq = dev_to_wq(dev); |
5950 | |
5951 | return scnprintf(buf, PAGE_SIZE, fmt: "%d\n" , (bool)!(wq->flags & WQ_UNBOUND)); |
5952 | } |
5953 | static DEVICE_ATTR_RO(per_cpu); |
5954 | |
5955 | static ssize_t max_active_show(struct device *dev, |
5956 | struct device_attribute *attr, char *buf) |
5957 | { |
5958 | struct workqueue_struct *wq = dev_to_wq(dev); |
5959 | |
5960 | return scnprintf(buf, PAGE_SIZE, fmt: "%d\n" , wq->saved_max_active); |
5961 | } |
5962 | |
5963 | static ssize_t max_active_store(struct device *dev, |
5964 | struct device_attribute *attr, const char *buf, |
5965 | size_t count) |
5966 | { |
5967 | struct workqueue_struct *wq = dev_to_wq(dev); |
5968 | int val; |
5969 | |
5970 | if (sscanf(buf, "%d" , &val) != 1 || val <= 0) |
5971 | return -EINVAL; |
5972 | |
5973 | workqueue_set_max_active(wq, val); |
5974 | return count; |
5975 | } |
5976 | static DEVICE_ATTR_RW(max_active); |
5977 | |
5978 | static struct attribute *wq_sysfs_attrs[] = { |
5979 | &dev_attr_per_cpu.attr, |
5980 | &dev_attr_max_active.attr, |
5981 | NULL, |
5982 | }; |
5983 | ATTRIBUTE_GROUPS(wq_sysfs); |
5984 | |
5985 | static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, |
5986 | char *buf) |
5987 | { |
5988 | struct workqueue_struct *wq = dev_to_wq(dev); |
5989 | int written; |
5990 | |
5991 | mutex_lock(&wq->mutex); |
5992 | written = scnprintf(buf, PAGE_SIZE, fmt: "%d\n" , wq->unbound_attrs->nice); |
5993 | mutex_unlock(lock: &wq->mutex); |
5994 | |
5995 | return written; |
5996 | } |
5997 | |
5998 | /* prepare workqueue_attrs for sysfs store operations */ |
5999 | static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) |
6000 | { |
6001 | struct workqueue_attrs *attrs; |
6002 | |
6003 | lockdep_assert_held(&wq_pool_mutex); |
6004 | |
6005 | attrs = alloc_workqueue_attrs(); |
6006 | if (!attrs) |
6007 | return NULL; |
6008 | |
6009 | copy_workqueue_attrs(to: attrs, from: wq->unbound_attrs); |
6010 | return attrs; |
6011 | } |
6012 | |
6013 | static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, |
6014 | const char *buf, size_t count) |
6015 | { |
6016 | struct workqueue_struct *wq = dev_to_wq(dev); |
6017 | struct workqueue_attrs *attrs; |
6018 | int ret = -ENOMEM; |
6019 | |
6020 | apply_wqattrs_lock(); |
6021 | |
6022 | attrs = wq_sysfs_prep_attrs(wq); |
6023 | if (!attrs) |
6024 | goto out_unlock; |
6025 | |
6026 | if (sscanf(buf, "%d" , &attrs->nice) == 1 && |
6027 | attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) |
6028 | ret = apply_workqueue_attrs_locked(wq, attrs); |
6029 | else |
6030 | ret = -EINVAL; |
6031 | |
6032 | out_unlock: |
6033 | apply_wqattrs_unlock(); |
6034 | free_workqueue_attrs(attrs); |
6035 | return ret ?: count; |
6036 | } |
6037 | |
6038 | static ssize_t wq_cpumask_show(struct device *dev, |
6039 | struct device_attribute *attr, char *buf) |
6040 | { |
6041 | struct workqueue_struct *wq = dev_to_wq(dev); |
6042 | int written; |
6043 | |
6044 | mutex_lock(&wq->mutex); |
6045 | written = scnprintf(buf, PAGE_SIZE, fmt: "%*pb\n" , |
6046 | cpumask_pr_args(wq->unbound_attrs->cpumask)); |
6047 | mutex_unlock(lock: &wq->mutex); |
6048 | return written; |
6049 | } |
6050 | |
6051 | static ssize_t wq_cpumask_store(struct device *dev, |
6052 | struct device_attribute *attr, |
6053 | const char *buf, size_t count) |
6054 | { |
6055 | struct workqueue_struct *wq = dev_to_wq(dev); |
6056 | struct workqueue_attrs *attrs; |
6057 | int ret = -ENOMEM; |
6058 | |
6059 | apply_wqattrs_lock(); |
6060 | |
6061 | attrs = wq_sysfs_prep_attrs(wq); |
6062 | if (!attrs) |
6063 | goto out_unlock; |
6064 | |
6065 | ret = cpumask_parse(buf, dstp: attrs->cpumask); |
6066 | if (!ret) |
6067 | ret = apply_workqueue_attrs_locked(wq, attrs); |
6068 | |
6069 | out_unlock: |
6070 | apply_wqattrs_unlock(); |
6071 | free_workqueue_attrs(attrs); |
6072 | return ret ?: count; |
6073 | } |
6074 | |
6075 | static ssize_t wq_affn_scope_show(struct device *dev, |
6076 | struct device_attribute *attr, char *buf) |
6077 | { |
6078 | struct workqueue_struct *wq = dev_to_wq(dev); |
6079 | int written; |
6080 | |
6081 | mutex_lock(&wq->mutex); |
6082 | if (wq->unbound_attrs->affn_scope == WQ_AFFN_DFL) |
6083 | written = scnprintf(buf, PAGE_SIZE, fmt: "%s (%s)\n" , |
6084 | wq_affn_names[WQ_AFFN_DFL], |
6085 | wq_affn_names[wq_affn_dfl]); |
6086 | else |
6087 | written = scnprintf(buf, PAGE_SIZE, fmt: "%s\n" , |
6088 | wq_affn_names[wq->unbound_attrs->affn_scope]); |
6089 | mutex_unlock(lock: &wq->mutex); |
6090 | |
6091 | return written; |
6092 | } |
6093 | |
6094 | static ssize_t wq_affn_scope_store(struct device *dev, |
6095 | struct device_attribute *attr, |
6096 | const char *buf, size_t count) |
6097 | { |
6098 | struct workqueue_struct *wq = dev_to_wq(dev); |
6099 | struct workqueue_attrs *attrs; |
6100 | int affn, ret = -ENOMEM; |
6101 | |
6102 | affn = parse_affn_scope(val: buf); |
6103 | if (affn < 0) |
6104 | return affn; |
6105 | |
6106 | apply_wqattrs_lock(); |
6107 | attrs = wq_sysfs_prep_attrs(wq); |
6108 | if (attrs) { |
6109 | attrs->affn_scope = affn; |
6110 | ret = apply_workqueue_attrs_locked(wq, attrs); |
6111 | } |
6112 | apply_wqattrs_unlock(); |
6113 | free_workqueue_attrs(attrs); |
6114 | return ret ?: count; |
6115 | } |
6116 | |
6117 | static ssize_t wq_affinity_strict_show(struct device *dev, |
6118 | struct device_attribute *attr, char *buf) |
6119 | { |
6120 | struct workqueue_struct *wq = dev_to_wq(dev); |
6121 | |
6122 | return scnprintf(buf, PAGE_SIZE, fmt: "%d\n" , |
6123 | wq->unbound_attrs->affn_strict); |
6124 | } |
6125 | |
6126 | static ssize_t wq_affinity_strict_store(struct device *dev, |
6127 | struct device_attribute *attr, |
6128 | const char *buf, size_t count) |
6129 | { |
6130 | struct workqueue_struct *wq = dev_to_wq(dev); |
6131 | struct workqueue_attrs *attrs; |
6132 | int v, ret = -ENOMEM; |
6133 | |
6134 | if (sscanf(buf, "%d" , &v) != 1) |
6135 | return -EINVAL; |
6136 | |
6137 | apply_wqattrs_lock(); |
6138 | attrs = wq_sysfs_prep_attrs(wq); |
6139 | if (attrs) { |
6140 | attrs->affn_strict = (bool)v; |
6141 | ret = apply_workqueue_attrs_locked(wq, attrs); |
6142 | } |
6143 | apply_wqattrs_unlock(); |
6144 | free_workqueue_attrs(attrs); |
6145 | return ret ?: count; |
6146 | } |
6147 | |
6148 | static struct device_attribute wq_sysfs_unbound_attrs[] = { |
6149 | __ATTR(nice, 0644, wq_nice_show, wq_nice_store), |
6150 | __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), |
6151 | __ATTR(affinity_scope, 0644, wq_affn_scope_show, wq_affn_scope_store), |
6152 | __ATTR(affinity_strict, 0644, wq_affinity_strict_show, wq_affinity_strict_store), |
6153 | __ATTR_NULL, |
6154 | }; |
6155 | |
6156 | static struct bus_type wq_subsys = { |
6157 | .name = "workqueue" , |
6158 | .dev_groups = wq_sysfs_groups, |
6159 | }; |
6160 | |
6161 | static ssize_t wq_unbound_cpumask_show(struct device *dev, |
6162 | struct device_attribute *attr, char *buf) |
6163 | { |
6164 | int written; |
6165 | |
6166 | mutex_lock(&wq_pool_mutex); |
6167 | written = scnprintf(buf, PAGE_SIZE, fmt: "%*pb\n" , |
6168 | cpumask_pr_args(wq_unbound_cpumask)); |
6169 | mutex_unlock(lock: &wq_pool_mutex); |
6170 | |
6171 | return written; |
6172 | } |
6173 | |
6174 | static ssize_t wq_unbound_cpumask_store(struct device *dev, |
6175 | struct device_attribute *attr, const char *buf, size_t count) |
6176 | { |
6177 | cpumask_var_t cpumask; |
6178 | int ret; |
6179 | |
6180 | if (!zalloc_cpumask_var(mask: &cpumask, GFP_KERNEL)) |
6181 | return -ENOMEM; |
6182 | |
6183 | ret = cpumask_parse(buf, dstp: cpumask); |
6184 | if (!ret) |
6185 | ret = workqueue_set_unbound_cpumask(cpumask); |
6186 | |
6187 | free_cpumask_var(mask: cpumask); |
6188 | return ret ? ret : count; |
6189 | } |
6190 | |
6191 | static struct device_attribute wq_sysfs_cpumask_attr = |
6192 | __ATTR(cpumask, 0644, wq_unbound_cpumask_show, |
6193 | wq_unbound_cpumask_store); |
6194 | |
6195 | static int __init wq_sysfs_init(void) |
6196 | { |
6197 | struct device *dev_root; |
6198 | int err; |
6199 | |
6200 | err = subsys_virtual_register(subsys: &wq_subsys, NULL); |
6201 | if (err) |
6202 | return err; |
6203 | |
6204 | dev_root = bus_get_dev_root(bus: &wq_subsys); |
6205 | if (dev_root) { |
6206 | err = device_create_file(device: dev_root, entry: &wq_sysfs_cpumask_attr); |
6207 | put_device(dev: dev_root); |
6208 | } |
6209 | return err; |
6210 | } |
6211 | core_initcall(wq_sysfs_init); |
6212 | |
6213 | static void wq_device_release(struct device *dev) |
6214 | { |
6215 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); |
6216 | |
6217 | kfree(objp: wq_dev); |
6218 | } |
6219 | |
6220 | /** |
6221 | * workqueue_sysfs_register - make a workqueue visible in sysfs |
6222 | * @wq: the workqueue to register |
6223 | * |
6224 | * Expose @wq in sysfs under /sys/bus/workqueue/devices. |
6225 | * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set |
6226 | * which is the preferred method. |
6227 | * |
6228 | * Workqueue user should use this function directly iff it wants to apply |
6229 | * workqueue_attrs before making the workqueue visible in sysfs; otherwise, |
6230 | * apply_workqueue_attrs() may race against userland updating the |
6231 | * attributes. |
6232 | * |
6233 | * Return: 0 on success, -errno on failure. |
6234 | */ |
6235 | int workqueue_sysfs_register(struct workqueue_struct *wq) |
6236 | { |
6237 | struct wq_device *wq_dev; |
6238 | int ret; |
6239 | |
6240 | /* |
6241 | * Adjusting max_active or creating new pwqs by applying |
6242 | * attributes breaks ordering guarantee. Disallow exposing ordered |
6243 | * workqueues. |
6244 | */ |
6245 | if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) |
6246 | return -EINVAL; |
6247 | |
6248 | wq->wq_dev = wq_dev = kzalloc(size: sizeof(*wq_dev), GFP_KERNEL); |
6249 | if (!wq_dev) |
6250 | return -ENOMEM; |
6251 | |
6252 | wq_dev->wq = wq; |
6253 | wq_dev->dev.bus = &wq_subsys; |
6254 | wq_dev->dev.release = wq_device_release; |
6255 | dev_set_name(dev: &wq_dev->dev, name: "%s" , wq->name); |
6256 | |
6257 | /* |
6258 | * unbound_attrs are created separately. Suppress uevent until |
6259 | * everything is ready. |
6260 | */ |
6261 | dev_set_uevent_suppress(dev: &wq_dev->dev, val: true); |
6262 | |
6263 | ret = device_register(dev: &wq_dev->dev); |
6264 | if (ret) { |
6265 | put_device(dev: &wq_dev->dev); |
6266 | wq->wq_dev = NULL; |
6267 | return ret; |
6268 | } |
6269 | |
6270 | if (wq->flags & WQ_UNBOUND) { |
6271 | struct device_attribute *attr; |
6272 | |
6273 | for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { |
6274 | ret = device_create_file(device: &wq_dev->dev, entry: attr); |
6275 | if (ret) { |
6276 | device_unregister(dev: &wq_dev->dev); |
6277 | wq->wq_dev = NULL; |
6278 | return ret; |
6279 | } |
6280 | } |
6281 | } |
6282 | |
6283 | dev_set_uevent_suppress(dev: &wq_dev->dev, val: false); |
6284 | kobject_uevent(kobj: &wq_dev->dev.kobj, action: KOBJ_ADD); |
6285 | return 0; |
6286 | } |
6287 | |
6288 | /** |
6289 | * workqueue_sysfs_unregister - undo workqueue_sysfs_register() |
6290 | * @wq: the workqueue to unregister |
6291 | * |
6292 | * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. |
6293 | */ |
6294 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) |
6295 | { |
6296 | struct wq_device *wq_dev = wq->wq_dev; |
6297 | |
6298 | if (!wq->wq_dev) |
6299 | return; |
6300 | |
6301 | wq->wq_dev = NULL; |
6302 | device_unregister(dev: &wq_dev->dev); |
6303 | } |
6304 | #else /* CONFIG_SYSFS */ |
6305 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } |
6306 | #endif /* CONFIG_SYSFS */ |
6307 | |
6308 | /* |
6309 | * Workqueue watchdog. |
6310 | * |
6311 | * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal |
6312 | * flush dependency, a concurrency managed work item which stays RUNNING |
6313 | * indefinitely. Workqueue stalls can be very difficult to debug as the |
6314 | * usual warning mechanisms don't trigger and internal workqueue state is |
6315 | * largely opaque. |
6316 | * |
6317 | * Workqueue watchdog monitors all worker pools periodically and dumps |
6318 | * state if some pools failed to make forward progress for a while where |
6319 | * forward progress is defined as the first item on ->worklist changing. |
6320 | * |
6321 | * This mechanism is controlled through the kernel parameter |
6322 | * "workqueue.watchdog_thresh" which can be updated at runtime through the |
6323 | * corresponding sysfs parameter file. |
6324 | */ |
6325 | #ifdef CONFIG_WQ_WATCHDOG |
6326 | |
6327 | static unsigned long wq_watchdog_thresh = 30; |
6328 | static struct timer_list wq_watchdog_timer; |
6329 | |
6330 | static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; |
6331 | static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; |
6332 | |
6333 | /* |
6334 | * Show workers that might prevent the processing of pending work items. |
6335 | * The only candidates are CPU-bound workers in the running state. |
6336 | * Pending work items should be handled by another idle worker |
6337 | * in all other situations. |
6338 | */ |
6339 | static void show_cpu_pool_hog(struct worker_pool *pool) |
6340 | { |
6341 | struct worker *worker; |
6342 | unsigned long flags; |
6343 | int bkt; |
6344 | |
6345 | raw_spin_lock_irqsave(&pool->lock, flags); |
6346 | |
6347 | hash_for_each(pool->busy_hash, bkt, worker, hentry) { |
6348 | if (task_is_running(worker->task)) { |
6349 | /* |
6350 | * Defer printing to avoid deadlocks in console |
6351 | * drivers that queue work while holding locks |
6352 | * also taken in their write paths. |
6353 | */ |
6354 | printk_deferred_enter(); |
6355 | |
6356 | pr_info("pool %d:\n" , pool->id); |
6357 | sched_show_task(p: worker->task); |
6358 | |
6359 | printk_deferred_exit(); |
6360 | } |
6361 | } |
6362 | |
6363 | raw_spin_unlock_irqrestore(&pool->lock, flags); |
6364 | } |
6365 | |
6366 | static void show_cpu_pools_hogs(void) |
6367 | { |
6368 | struct worker_pool *pool; |
6369 | int pi; |
6370 | |
6371 | pr_info("Showing backtraces of running workers in stalled CPU-bound worker pools:\n" ); |
6372 | |
6373 | rcu_read_lock(); |
6374 | |
6375 | for_each_pool(pool, pi) { |
6376 | if (pool->cpu_stall) |
6377 | show_cpu_pool_hog(pool); |
6378 | |
6379 | } |
6380 | |
6381 | rcu_read_unlock(); |
6382 | } |
6383 | |
6384 | static void wq_watchdog_reset_touched(void) |
6385 | { |
6386 | int cpu; |
6387 | |
6388 | wq_watchdog_touched = jiffies; |
6389 | for_each_possible_cpu(cpu) |
6390 | per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; |
6391 | } |
6392 | |
6393 | static void wq_watchdog_timer_fn(struct timer_list *unused) |
6394 | { |
6395 | unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; |
6396 | bool lockup_detected = false; |
6397 | bool cpu_pool_stall = false; |
6398 | unsigned long now = jiffies; |
6399 | struct worker_pool *pool; |
6400 | int pi; |
6401 | |
6402 | if (!thresh) |
6403 | return; |
6404 | |
6405 | rcu_read_lock(); |
6406 | |
6407 | for_each_pool(pool, pi) { |
6408 | unsigned long pool_ts, touched, ts; |
6409 | |
6410 | pool->cpu_stall = false; |
6411 | if (list_empty(head: &pool->worklist)) |
6412 | continue; |
6413 | |
6414 | /* |
6415 | * If a virtual machine is stopped by the host it can look to |
6416 | * the watchdog like a stall. |
6417 | */ |
6418 | kvm_check_and_clear_guest_paused(); |
6419 | |
6420 | /* get the latest of pool and touched timestamps */ |
6421 | if (pool->cpu >= 0) |
6422 | touched = READ_ONCE(per_cpu(wq_watchdog_touched_cpu, pool->cpu)); |
6423 | else |
6424 | touched = READ_ONCE(wq_watchdog_touched); |
6425 | pool_ts = READ_ONCE(pool->watchdog_ts); |
6426 | |
6427 | if (time_after(pool_ts, touched)) |
6428 | ts = pool_ts; |
6429 | else |
6430 | ts = touched; |
6431 | |
6432 | /* did we stall? */ |
6433 | if (time_after(now, ts + thresh)) { |
6434 | lockup_detected = true; |
6435 | if (pool->cpu >= 0) { |
6436 | pool->cpu_stall = true; |
6437 | cpu_pool_stall = true; |
6438 | } |
6439 | pr_emerg("BUG: workqueue lockup - pool" ); |
6440 | pr_cont_pool_info(pool); |
6441 | pr_cont(" stuck for %us!\n" , |
6442 | jiffies_to_msecs(now - pool_ts) / 1000); |
6443 | } |
6444 | |
6445 | |
6446 | } |
6447 | |
6448 | rcu_read_unlock(); |
6449 | |
6450 | if (lockup_detected) |
6451 | show_all_workqueues(); |
6452 | |
6453 | if (cpu_pool_stall) |
6454 | show_cpu_pools_hogs(); |
6455 | |
6456 | wq_watchdog_reset_touched(); |
6457 | mod_timer(timer: &wq_watchdog_timer, expires: jiffies + thresh); |
6458 | } |
6459 | |
6460 | notrace void wq_watchdog_touch(int cpu) |
6461 | { |
6462 | if (cpu >= 0) |
6463 | per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; |
6464 | |
6465 | wq_watchdog_touched = jiffies; |
6466 | } |
6467 | |
6468 | static void wq_watchdog_set_thresh(unsigned long thresh) |
6469 | { |
6470 | wq_watchdog_thresh = 0; |
6471 | del_timer_sync(timer: &wq_watchdog_timer); |
6472 | |
6473 | if (thresh) { |
6474 | wq_watchdog_thresh = thresh; |
6475 | wq_watchdog_reset_touched(); |
6476 | mod_timer(timer: &wq_watchdog_timer, expires: jiffies + thresh * HZ); |
6477 | } |
6478 | } |
6479 | |
6480 | static int wq_watchdog_param_set_thresh(const char *val, |
6481 | const struct kernel_param *kp) |
6482 | { |
6483 | unsigned long thresh; |
6484 | int ret; |
6485 | |
6486 | ret = kstrtoul(s: val, base: 0, res: &thresh); |
6487 | if (ret) |
6488 | return ret; |
6489 | |
6490 | if (system_wq) |
6491 | wq_watchdog_set_thresh(thresh); |
6492 | else |
6493 | wq_watchdog_thresh = thresh; |
6494 | |
6495 | return 0; |
6496 | } |
6497 | |
6498 | static const struct kernel_param_ops wq_watchdog_thresh_ops = { |
6499 | .set = wq_watchdog_param_set_thresh, |
6500 | .get = param_get_ulong, |
6501 | }; |
6502 | |
6503 | module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh, |
6504 | 0644); |
6505 | |
6506 | static void wq_watchdog_init(void) |
6507 | { |
6508 | timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE); |
6509 | wq_watchdog_set_thresh(thresh: wq_watchdog_thresh); |
6510 | } |
6511 | |
6512 | #else /* CONFIG_WQ_WATCHDOG */ |
6513 | |
6514 | static inline void wq_watchdog_init(void) { } |
6515 | |
6516 | #endif /* CONFIG_WQ_WATCHDOG */ |
6517 | |
6518 | /** |
6519 | * workqueue_init_early - early init for workqueue subsystem |
6520 | * |
6521 | * This is the first step of three-staged workqueue subsystem initialization and |
6522 | * invoked as soon as the bare basics - memory allocation, cpumasks and idr are |
6523 | * up. It sets up all the data structures and system workqueues and allows early |
6524 | * boot code to create workqueues and queue/cancel work items. Actual work item |
6525 | * execution starts only after kthreads can be created and scheduled right |
6526 | * before early initcalls. |
6527 | */ |
6528 | void __init workqueue_init_early(void) |
6529 | { |
6530 | struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_SYSTEM]; |
6531 | int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; |
6532 | int i, cpu; |
6533 | |
6534 | BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); |
6535 | |
6536 | BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL)); |
6537 | cpumask_copy(dstp: wq_unbound_cpumask, srcp: housekeeping_cpumask(type: HK_TYPE_WQ)); |
6538 | cpumask_and(dstp: wq_unbound_cpumask, src1p: wq_unbound_cpumask, src2p: housekeeping_cpumask(type: HK_TYPE_DOMAIN)); |
6539 | |
6540 | if (!cpumask_empty(srcp: &wq_cmdline_cpumask)) |
6541 | cpumask_and(dstp: wq_unbound_cpumask, src1p: wq_unbound_cpumask, src2p: &wq_cmdline_cpumask); |
6542 | |
6543 | pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); |
6544 | |
6545 | wq_update_pod_attrs_buf = alloc_workqueue_attrs(); |
6546 | BUG_ON(!wq_update_pod_attrs_buf); |
6547 | |
6548 | /* initialize WQ_AFFN_SYSTEM pods */ |
6549 | pt->pod_cpus = kcalloc(n: 1, size: sizeof(pt->pod_cpus[0]), GFP_KERNEL); |
6550 | pt->pod_node = kcalloc(n: 1, size: sizeof(pt->pod_node[0]), GFP_KERNEL); |
6551 | pt->cpu_pod = kcalloc(n: nr_cpu_ids, size: sizeof(pt->cpu_pod[0]), GFP_KERNEL); |
6552 | BUG_ON(!pt->pod_cpus || !pt->pod_node || !pt->cpu_pod); |
6553 | |
6554 | BUG_ON(!zalloc_cpumask_var_node(&pt->pod_cpus[0], GFP_KERNEL, NUMA_NO_NODE)); |
6555 | |
6556 | pt->nr_pods = 1; |
6557 | cpumask_copy(dstp: pt->pod_cpus[0], cpu_possible_mask); |
6558 | pt->pod_node[0] = NUMA_NO_NODE; |
6559 | pt->cpu_pod[0] = 0; |
6560 | |
6561 | /* initialize CPU pools */ |
6562 | for_each_possible_cpu(cpu) { |
6563 | struct worker_pool *pool; |
6564 | |
6565 | i = 0; |
6566 | for_each_cpu_worker_pool(pool, cpu) { |
6567 | BUG_ON(init_worker_pool(pool)); |
6568 | pool->cpu = cpu; |
6569 | cpumask_copy(dstp: pool->attrs->cpumask, cpumask_of(cpu)); |
6570 | cpumask_copy(dstp: pool->attrs->__pod_cpumask, cpumask_of(cpu)); |
6571 | pool->attrs->nice = std_nice[i++]; |
6572 | pool->attrs->affn_strict = true; |
6573 | pool->node = cpu_to_node(cpu); |
6574 | |
6575 | /* alloc pool ID */ |
6576 | mutex_lock(&wq_pool_mutex); |
6577 | BUG_ON(worker_pool_assign_id(pool)); |
6578 | mutex_unlock(lock: &wq_pool_mutex); |
6579 | } |
6580 | } |
6581 | |
6582 | /* create default unbound and ordered wq attrs */ |
6583 | for (i = 0; i < NR_STD_WORKER_POOLS; i++) { |
6584 | struct workqueue_attrs *attrs; |
6585 | |
6586 | BUG_ON(!(attrs = alloc_workqueue_attrs())); |
6587 | attrs->nice = std_nice[i]; |
6588 | unbound_std_wq_attrs[i] = attrs; |
6589 | |
6590 | /* |
6591 | * An ordered wq should have only one pwq as ordering is |
6592 | * guaranteed by max_active which is enforced by pwqs. |
6593 | */ |
6594 | BUG_ON(!(attrs = alloc_workqueue_attrs())); |
6595 | attrs->nice = std_nice[i]; |
6596 | attrs->ordered = true; |
6597 | ordered_wq_attrs[i] = attrs; |
6598 | } |
6599 | |
6600 | system_wq = alloc_workqueue("events" , 0, 0); |
6601 | system_highpri_wq = alloc_workqueue("events_highpri" , WQ_HIGHPRI, 0); |
6602 | system_long_wq = alloc_workqueue("events_long" , 0, 0); |
6603 | system_unbound_wq = alloc_workqueue("events_unbound" , WQ_UNBOUND, |
6604 | WQ_MAX_ACTIVE); |
6605 | system_freezable_wq = alloc_workqueue("events_freezable" , |
6606 | WQ_FREEZABLE, 0); |
6607 | system_power_efficient_wq = alloc_workqueue("events_power_efficient" , |
6608 | WQ_POWER_EFFICIENT, 0); |
6609 | system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient" , |
6610 | WQ_FREEZABLE | WQ_POWER_EFFICIENT, |
6611 | 0); |
6612 | BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || |
6613 | !system_unbound_wq || !system_freezable_wq || |
6614 | !system_power_efficient_wq || |
6615 | !system_freezable_power_efficient_wq); |
6616 | } |
6617 | |
6618 | static void __init wq_cpu_intensive_thresh_init(void) |
6619 | { |
6620 | unsigned long thresh; |
6621 | unsigned long bogo; |
6622 | |
6623 | pwq_release_worker = kthread_create_worker(flags: 0, namefmt: "pool_workqueue_release" ); |
6624 | BUG_ON(IS_ERR(pwq_release_worker)); |
6625 | |
6626 | /* if the user set it to a specific value, keep it */ |
6627 | if (wq_cpu_intensive_thresh_us != ULONG_MAX) |
6628 | return; |
6629 | |
6630 | /* |
6631 | * The default of 10ms is derived from the fact that most modern (as of |
6632 | * 2023) processors can do a lot in 10ms and that it's just below what |
6633 | * most consider human-perceivable. However, the kernel also runs on a |
6634 | * lot slower CPUs including microcontrollers where the threshold is way |
6635 | * too low. |
6636 | * |
6637 | * Let's scale up the threshold upto 1 second if BogoMips is below 4000. |
6638 | * This is by no means accurate but it doesn't have to be. The mechanism |
6639 | * is still useful even when the threshold is fully scaled up. Also, as |
6640 | * the reports would usually be applicable to everyone, some machines |
6641 | * operating on longer thresholds won't significantly diminish their |
6642 | * usefulness. |
6643 | */ |
6644 | thresh = 10 * USEC_PER_MSEC; |
6645 | |
6646 | /* see init/calibrate.c for lpj -> BogoMIPS calculation */ |
6647 | bogo = max_t(unsigned long, loops_per_jiffy / 500000 * HZ, 1); |
6648 | if (bogo < 4000) |
6649 | thresh = min_t(unsigned long, thresh * 4000 / bogo, USEC_PER_SEC); |
6650 | |
6651 | pr_debug("wq_cpu_intensive_thresh: lpj=%lu BogoMIPS=%lu thresh_us=%lu\n" , |
6652 | loops_per_jiffy, bogo, thresh); |
6653 | |
6654 | wq_cpu_intensive_thresh_us = thresh; |
6655 | } |
6656 | |
6657 | /** |
6658 | * workqueue_init - bring workqueue subsystem fully online |
6659 | * |
6660 | * This is the second step of three-staged workqueue subsystem initialization |
6661 | * and invoked as soon as kthreads can be created and scheduled. Workqueues have |
6662 | * been created and work items queued on them, but there are no kworkers |
6663 | * executing the work items yet. Populate the worker pools with the initial |
6664 | * workers and enable future kworker creations. |
6665 | */ |
6666 | void __init workqueue_init(void) |
6667 | { |
6668 | struct workqueue_struct *wq; |
6669 | struct worker_pool *pool; |
6670 | int cpu, bkt; |
6671 | |
6672 | wq_cpu_intensive_thresh_init(); |
6673 | |
6674 | mutex_lock(&wq_pool_mutex); |
6675 | |
6676 | /* |
6677 | * Per-cpu pools created earlier could be missing node hint. Fix them |
6678 | * up. Also, create a rescuer for workqueues that requested it. |
6679 | */ |
6680 | for_each_possible_cpu(cpu) { |
6681 | for_each_cpu_worker_pool(pool, cpu) { |
6682 | pool->node = cpu_to_node(cpu); |
6683 | } |
6684 | } |
6685 | |
6686 | list_for_each_entry(wq, &workqueues, list) { |
6687 | WARN(init_rescuer(wq), |
6688 | "workqueue: failed to create early rescuer for %s" , |
6689 | wq->name); |
6690 | } |
6691 | |
6692 | mutex_unlock(lock: &wq_pool_mutex); |
6693 | |
6694 | /* create the initial workers */ |
6695 | for_each_online_cpu(cpu) { |
6696 | for_each_cpu_worker_pool(pool, cpu) { |
6697 | pool->flags &= ~POOL_DISASSOCIATED; |
6698 | BUG_ON(!create_worker(pool)); |
6699 | } |
6700 | } |
6701 | |
6702 | hash_for_each(unbound_pool_hash, bkt, pool, hash_node) |
6703 | BUG_ON(!create_worker(pool)); |
6704 | |
6705 | wq_online = true; |
6706 | wq_watchdog_init(); |
6707 | } |
6708 | |
6709 | /* |
6710 | * Initialize @pt by first initializing @pt->cpu_pod[] with pod IDs according to |
6711 | * @cpu_shares_pod(). Each subset of CPUs that share a pod is assigned a unique |
6712 | * and consecutive pod ID. The rest of @pt is initialized accordingly. |
6713 | */ |
6714 | static void __init init_pod_type(struct wq_pod_type *pt, |
6715 | bool (*cpus_share_pod)(int, int)) |
6716 | { |
6717 | int cur, pre, cpu, pod; |
6718 | |
6719 | pt->nr_pods = 0; |
6720 | |
6721 | /* init @pt->cpu_pod[] according to @cpus_share_pod() */ |
6722 | pt->cpu_pod = kcalloc(n: nr_cpu_ids, size: sizeof(pt->cpu_pod[0]), GFP_KERNEL); |
6723 | BUG_ON(!pt->cpu_pod); |
6724 | |
6725 | for_each_possible_cpu(cur) { |
6726 | for_each_possible_cpu(pre) { |
6727 | if (pre >= cur) { |
6728 | pt->cpu_pod[cur] = pt->nr_pods++; |
6729 | break; |
6730 | } |
6731 | if (cpus_share_pod(cur, pre)) { |
6732 | pt->cpu_pod[cur] = pt->cpu_pod[pre]; |
6733 | break; |
6734 | } |
6735 | } |
6736 | } |
6737 | |
6738 | /* init the rest to match @pt->cpu_pod[] */ |
6739 | pt->pod_cpus = kcalloc(n: pt->nr_pods, size: sizeof(pt->pod_cpus[0]), GFP_KERNEL); |
6740 | pt->pod_node = kcalloc(n: pt->nr_pods, size: sizeof(pt->pod_node[0]), GFP_KERNEL); |
6741 | BUG_ON(!pt->pod_cpus || !pt->pod_node); |
6742 | |
6743 | for (pod = 0; pod < pt->nr_pods; pod++) |
6744 | BUG_ON(!zalloc_cpumask_var(&pt->pod_cpus[pod], GFP_KERNEL)); |
6745 | |
6746 | for_each_possible_cpu(cpu) { |
6747 | cpumask_set_cpu(cpu, dstp: pt->pod_cpus[pt->cpu_pod[cpu]]); |
6748 | pt->pod_node[pt->cpu_pod[cpu]] = cpu_to_node(cpu); |
6749 | } |
6750 | } |
6751 | |
6752 | static bool __init cpus_dont_share(int cpu0, int cpu1) |
6753 | { |
6754 | return false; |
6755 | } |
6756 | |
6757 | static bool __init cpus_share_smt(int cpu0, int cpu1) |
6758 | { |
6759 | #ifdef CONFIG_SCHED_SMT |
6760 | return cpumask_test_cpu(cpu: cpu0, cpumask: cpu_smt_mask(cpu: cpu1)); |
6761 | #else |
6762 | return false; |
6763 | #endif |
6764 | } |
6765 | |
6766 | static bool __init cpus_share_numa(int cpu0, int cpu1) |
6767 | { |
6768 | return cpu_to_node(cpu: cpu0) == cpu_to_node(cpu: cpu1); |
6769 | } |
6770 | |
6771 | /** |
6772 | * workqueue_init_topology - initialize CPU pods for unbound workqueues |
6773 | * |
6774 | * This is the third step of there-staged workqueue subsystem initialization and |
6775 | * invoked after SMP and topology information are fully initialized. It |
6776 | * initializes the unbound CPU pods accordingly. |
6777 | */ |
6778 | void __init workqueue_init_topology(void) |
6779 | { |
6780 | struct workqueue_struct *wq; |
6781 | int cpu; |
6782 | |
6783 | init_pod_type(pt: &wq_pod_types[WQ_AFFN_CPU], cpus_share_pod: cpus_dont_share); |
6784 | init_pod_type(pt: &wq_pod_types[WQ_AFFN_SMT], cpus_share_pod: cpus_share_smt); |
6785 | init_pod_type(pt: &wq_pod_types[WQ_AFFN_CACHE], cpus_share_pod: cpus_share_cache); |
6786 | init_pod_type(pt: &wq_pod_types[WQ_AFFN_NUMA], cpus_share_pod: cpus_share_numa); |
6787 | |
6788 | mutex_lock(&wq_pool_mutex); |
6789 | |
6790 | /* |
6791 | * Workqueues allocated earlier would have all CPUs sharing the default |
6792 | * worker pool. Explicitly call wq_update_pod() on all workqueue and CPU |
6793 | * combinations to apply per-pod sharing. |
6794 | */ |
6795 | list_for_each_entry(wq, &workqueues, list) { |
6796 | for_each_online_cpu(cpu) { |
6797 | wq_update_pod(wq, cpu, hotplug_cpu: cpu, online: true); |
6798 | } |
6799 | } |
6800 | |
6801 | mutex_unlock(lock: &wq_pool_mutex); |
6802 | } |
6803 | |
6804 | void __warn_flushing_systemwide_wq(void) |
6805 | { |
6806 | pr_warn("WARNING: Flushing system-wide workqueues will be prohibited in near future.\n" ); |
6807 | dump_stack(); |
6808 | } |
6809 | EXPORT_SYMBOL(__warn_flushing_systemwide_wq); |
6810 | |
6811 | static int __init workqueue_unbound_cpus_setup(char *str) |
6812 | { |
6813 | if (cpulist_parse(buf: str, dstp: &wq_cmdline_cpumask) < 0) { |
6814 | cpumask_clear(dstp: &wq_cmdline_cpumask); |
6815 | pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n" ); |
6816 | } |
6817 | |
6818 | return 1; |
6819 | } |
6820 | __setup("workqueue.unbound_cpus=" , workqueue_unbound_cpus_setup); |
6821 | |