1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | /* |
3 | * linux/cgroup-defs.h - basic definitions for cgroup |
4 | * |
5 | * This file provides basic type and interface. Include this file directly |
6 | * only if necessary to avoid cyclic dependencies. |
7 | */ |
8 | #ifndef _LINUX_CGROUP_DEFS_H |
9 | #define _LINUX_CGROUP_DEFS_H |
10 | |
11 | #include <linux/limits.h> |
12 | #include <linux/list.h> |
13 | #include <linux/idr.h> |
14 | #include <linux/wait.h> |
15 | #include <linux/mutex.h> |
16 | #include <linux/rcupdate.h> |
17 | #include <linux/refcount.h> |
18 | #include <linux/percpu-refcount.h> |
19 | #include <linux/percpu-rwsem.h> |
20 | #include <linux/u64_stats_sync.h> |
21 | #include <linux/workqueue.h> |
22 | #include <linux/bpf-cgroup.h> |
23 | #include <linux/psi_types.h> |
24 | |
25 | #ifdef CONFIG_CGROUPS |
26 | |
27 | struct cgroup; |
28 | struct cgroup_root; |
29 | struct cgroup_subsys; |
30 | struct cgroup_taskset; |
31 | struct kernfs_node; |
32 | struct kernfs_ops; |
33 | struct kernfs_open_file; |
34 | struct seq_file; |
35 | struct poll_table_struct; |
36 | |
37 | #define MAX_CGROUP_TYPE_NAMELEN 32 |
38 | #define MAX_CGROUP_ROOT_NAMELEN 64 |
39 | #define MAX_CFTYPE_NAME 64 |
40 | |
41 | /* define the enumeration of all cgroup subsystems */ |
42 | #define SUBSYS(_x) _x ## _cgrp_id, |
43 | enum cgroup_subsys_id { |
44 | #include <linux/cgroup_subsys.h> |
45 | CGROUP_SUBSYS_COUNT, |
46 | }; |
47 | #undef SUBSYS |
48 | |
49 | /* bits in struct cgroup_subsys_state flags field */ |
50 | enum { |
51 | CSS_NO_REF = (1 << 0), /* no reference counting for this css */ |
52 | CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */ |
53 | CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */ |
54 | CSS_VISIBLE = (1 << 3), /* css is visible to userland */ |
55 | CSS_DYING = (1 << 4), /* css is dying */ |
56 | }; |
57 | |
58 | /* bits in struct cgroup flags field */ |
59 | enum { |
60 | /* Control Group requires release notifications to userspace */ |
61 | CGRP_NOTIFY_ON_RELEASE, |
62 | /* |
63 | * Clone the parent's configuration when creating a new child |
64 | * cpuset cgroup. For historical reasons, this option can be |
65 | * specified at mount time and thus is implemented here. |
66 | */ |
67 | CGRP_CPUSET_CLONE_CHILDREN, |
68 | }; |
69 | |
70 | /* cgroup_root->flags */ |
71 | enum { |
72 | CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */ |
73 | CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */ |
74 | |
75 | /* |
76 | * Consider namespaces as delegation boundaries. If this flag is |
77 | * set, controller specific interface files in a namespace root |
78 | * aren't writeable from inside the namespace. |
79 | */ |
80 | CGRP_ROOT_NS_DELEGATE = (1 << 3), |
81 | |
82 | /* |
83 | * Enable cpuset controller in v1 cgroup to use v2 behavior. |
84 | */ |
85 | CGRP_ROOT_CPUSET_V2_MODE = (1 << 4), |
86 | }; |
87 | |
88 | /* cftype->flags */ |
89 | enum { |
90 | CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */ |
91 | CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */ |
92 | CFTYPE_NS_DELEGATABLE = (1 << 2), /* writeable beyond delegation boundaries */ |
93 | |
94 | CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */ |
95 | CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */ |
96 | CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */ |
97 | |
98 | /* internal flags, do not use outside cgroup core proper */ |
99 | __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */ |
100 | __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */ |
101 | }; |
102 | |
103 | /* |
104 | * cgroup_file is the handle for a file instance created in a cgroup which |
105 | * is used, for example, to generate file changed notifications. This can |
106 | * be obtained by setting cftype->file_offset. |
107 | */ |
108 | struct cgroup_file { |
109 | /* do not access any fields from outside cgroup core */ |
110 | struct kernfs_node *kn; |
111 | unsigned long notified_at; |
112 | struct timer_list notify_timer; |
113 | }; |
114 | |
115 | /* |
116 | * Per-subsystem/per-cgroup state maintained by the system. This is the |
117 | * fundamental structural building block that controllers deal with. |
118 | * |
119 | * Fields marked with "PI:" are public and immutable and may be accessed |
120 | * directly without synchronization. |
121 | */ |
122 | struct cgroup_subsys_state { |
123 | /* PI: the cgroup that this css is attached to */ |
124 | struct cgroup *cgroup; |
125 | |
126 | /* PI: the cgroup subsystem that this css is attached to */ |
127 | struct cgroup_subsys *ss; |
128 | |
129 | /* reference count - access via css_[try]get() and css_put() */ |
130 | struct percpu_ref refcnt; |
131 | |
132 | /* siblings list anchored at the parent's ->children */ |
133 | struct list_head sibling; |
134 | struct list_head children; |
135 | |
136 | /* flush target list anchored at cgrp->rstat_css_list */ |
137 | struct list_head rstat_css_node; |
138 | |
139 | /* |
140 | * PI: Subsys-unique ID. 0 is unused and root is always 1. The |
141 | * matching css can be looked up using css_from_id(). |
142 | */ |
143 | int id; |
144 | |
145 | unsigned int flags; |
146 | |
147 | /* |
148 | * Monotonically increasing unique serial number which defines a |
149 | * uniform order among all csses. It's guaranteed that all |
150 | * ->children lists are in the ascending order of ->serial_nr and |
151 | * used to allow interrupting and resuming iterations. |
152 | */ |
153 | u64 serial_nr; |
154 | |
155 | /* |
156 | * Incremented by online self and children. Used to guarantee that |
157 | * parents are not offlined before their children. |
158 | */ |
159 | atomic_t online_cnt; |
160 | |
161 | /* percpu_ref killing and RCU release */ |
162 | struct work_struct destroy_work; |
163 | struct rcu_work destroy_rwork; |
164 | |
165 | /* |
166 | * PI: the parent css. Placed here for cache proximity to following |
167 | * fields of the containing structure. |
168 | */ |
169 | struct cgroup_subsys_state *parent; |
170 | }; |
171 | |
172 | /* |
173 | * A css_set is a structure holding pointers to a set of |
174 | * cgroup_subsys_state objects. This saves space in the task struct |
175 | * object and speeds up fork()/exit(), since a single inc/dec and a |
176 | * list_add()/del() can bump the reference count on the entire cgroup |
177 | * set for a task. |
178 | */ |
179 | struct css_set { |
180 | /* |
181 | * Set of subsystem states, one for each subsystem. This array is |
182 | * immutable after creation apart from the init_css_set during |
183 | * subsystem registration (at boot time). |
184 | */ |
185 | struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; |
186 | |
187 | /* reference count */ |
188 | refcount_t refcount; |
189 | |
190 | /* |
191 | * For a domain cgroup, the following points to self. If threaded, |
192 | * to the matching cset of the nearest domain ancestor. The |
193 | * dom_cset provides access to the domain cgroup and its csses to |
194 | * which domain level resource consumptions should be charged. |
195 | */ |
196 | struct css_set *dom_cset; |
197 | |
198 | /* the default cgroup associated with this css_set */ |
199 | struct cgroup *dfl_cgrp; |
200 | |
201 | /* internal task count, protected by css_set_lock */ |
202 | int nr_tasks; |
203 | |
204 | /* |
205 | * Lists running through all tasks using this cgroup group. |
206 | * mg_tasks lists tasks which belong to this cset but are in the |
207 | * process of being migrated out or in. Protected by |
208 | * css_set_rwsem, but, during migration, once tasks are moved to |
209 | * mg_tasks, it can be read safely while holding cgroup_mutex. |
210 | */ |
211 | struct list_head tasks; |
212 | struct list_head mg_tasks; |
213 | |
214 | /* all css_task_iters currently walking this cset */ |
215 | struct list_head task_iters; |
216 | |
217 | /* |
218 | * On the default hierarhcy, ->subsys[ssid] may point to a css |
219 | * attached to an ancestor instead of the cgroup this css_set is |
220 | * associated with. The following node is anchored at |
221 | * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to |
222 | * iterate through all css's attached to a given cgroup. |
223 | */ |
224 | struct list_head e_cset_node[CGROUP_SUBSYS_COUNT]; |
225 | |
226 | /* all threaded csets whose ->dom_cset points to this cset */ |
227 | struct list_head threaded_csets; |
228 | struct list_head threaded_csets_node; |
229 | |
230 | /* |
231 | * List running through all cgroup groups in the same hash |
232 | * slot. Protected by css_set_lock |
233 | */ |
234 | struct hlist_node hlist; |
235 | |
236 | /* |
237 | * List of cgrp_cset_links pointing at cgroups referenced from this |
238 | * css_set. Protected by css_set_lock. |
239 | */ |
240 | struct list_head cgrp_links; |
241 | |
242 | /* |
243 | * List of csets participating in the on-going migration either as |
244 | * source or destination. Protected by cgroup_mutex. |
245 | */ |
246 | struct list_head mg_preload_node; |
247 | struct list_head mg_node; |
248 | |
249 | /* |
250 | * If this cset is acting as the source of migration the following |
251 | * two fields are set. mg_src_cgrp and mg_dst_cgrp are |
252 | * respectively the source and destination cgroups of the on-going |
253 | * migration. mg_dst_cset is the destination cset the target tasks |
254 | * on this cset should be migrated to. Protected by cgroup_mutex. |
255 | */ |
256 | struct cgroup *mg_src_cgrp; |
257 | struct cgroup *mg_dst_cgrp; |
258 | struct css_set *mg_dst_cset; |
259 | |
260 | /* dead and being drained, ignore for migration */ |
261 | bool dead; |
262 | |
263 | /* For RCU-protected deletion */ |
264 | struct rcu_head rcu_head; |
265 | }; |
266 | |
267 | struct cgroup_base_stat { |
268 | struct task_cputime cputime; |
269 | }; |
270 | |
271 | /* |
272 | * rstat - cgroup scalable recursive statistics. Accounting is done |
273 | * per-cpu in cgroup_rstat_cpu which is then lazily propagated up the |
274 | * hierarchy on reads. |
275 | * |
276 | * When a stat gets updated, the cgroup_rstat_cpu and its ancestors are |
277 | * linked into the updated tree. On the following read, propagation only |
278 | * considers and consumes the updated tree. This makes reading O(the |
279 | * number of descendants which have been active since last read) instead of |
280 | * O(the total number of descendants). |
281 | * |
282 | * This is important because there can be a lot of (draining) cgroups which |
283 | * aren't active and stat may be read frequently. The combination can |
284 | * become very expensive. By propagating selectively, increasing reading |
285 | * frequency decreases the cost of each read. |
286 | * |
287 | * This struct hosts both the fields which implement the above - |
288 | * updated_children and updated_next - and the fields which track basic |
289 | * resource statistics on top of it - bsync, bstat and last_bstat. |
290 | */ |
291 | struct cgroup_rstat_cpu { |
292 | /* |
293 | * ->bsync protects ->bstat. These are the only fields which get |
294 | * updated in the hot path. |
295 | */ |
296 | struct u64_stats_sync bsync; |
297 | struct cgroup_base_stat bstat; |
298 | |
299 | /* |
300 | * Snapshots at the last reading. These are used to calculate the |
301 | * deltas to propagate to the global counters. |
302 | */ |
303 | struct cgroup_base_stat last_bstat; |
304 | |
305 | /* |
306 | * Child cgroups with stat updates on this cpu since the last read |
307 | * are linked on the parent's ->updated_children through |
308 | * ->updated_next. |
309 | * |
310 | * In addition to being more compact, singly-linked list pointing |
311 | * to the cgroup makes it unnecessary for each per-cpu struct to |
312 | * point back to the associated cgroup. |
313 | * |
314 | * Protected by per-cpu cgroup_rstat_cpu_lock. |
315 | */ |
316 | struct cgroup *updated_children; /* terminated by self cgroup */ |
317 | struct cgroup *updated_next; /* NULL iff not on the list */ |
318 | }; |
319 | |
320 | struct cgroup { |
321 | /* self css with NULL ->ss, points back to this cgroup */ |
322 | struct cgroup_subsys_state self; |
323 | |
324 | unsigned long flags; /* "unsigned long" so bitops work */ |
325 | |
326 | /* |
327 | * idr allocated in-hierarchy ID. |
328 | * |
329 | * ID 0 is not used, the ID of the root cgroup is always 1, and a |
330 | * new cgroup will be assigned with a smallest available ID. |
331 | * |
332 | * Allocating/Removing ID must be protected by cgroup_mutex. |
333 | */ |
334 | int id; |
335 | |
336 | /* |
337 | * The depth this cgroup is at. The root is at depth zero and each |
338 | * step down the hierarchy increments the level. This along with |
339 | * ancestor_ids[] can determine whether a given cgroup is a |
340 | * descendant of another without traversing the hierarchy. |
341 | */ |
342 | int level; |
343 | |
344 | /* Maximum allowed descent tree depth */ |
345 | int max_depth; |
346 | |
347 | /* |
348 | * Keep track of total numbers of visible and dying descent cgroups. |
349 | * Dying cgroups are cgroups which were deleted by a user, |
350 | * but are still existing because someone else is holding a reference. |
351 | * max_descendants is a maximum allowed number of descent cgroups. |
352 | */ |
353 | int nr_descendants; |
354 | int nr_dying_descendants; |
355 | int max_descendants; |
356 | |
357 | /* |
358 | * Each non-empty css_set associated with this cgroup contributes |
359 | * one to nr_populated_csets. The counter is zero iff this cgroup |
360 | * doesn't have any tasks. |
361 | * |
362 | * All children which have non-zero nr_populated_csets and/or |
363 | * nr_populated_children of their own contribute one to either |
364 | * nr_populated_domain_children or nr_populated_threaded_children |
365 | * depending on their type. Each counter is zero iff all cgroups |
366 | * of the type in the subtree proper don't have any tasks. |
367 | */ |
368 | int nr_populated_csets; |
369 | int nr_populated_domain_children; |
370 | int nr_populated_threaded_children; |
371 | |
372 | int nr_threaded_children; /* # of live threaded child cgroups */ |
373 | |
374 | struct kernfs_node *kn; /* cgroup kernfs entry */ |
375 | struct cgroup_file procs_file; /* handle for "cgroup.procs" */ |
376 | struct cgroup_file events_file; /* handle for "cgroup.events" */ |
377 | |
378 | /* |
379 | * The bitmask of subsystems enabled on the child cgroups. |
380 | * ->subtree_control is the one configured through |
381 | * "cgroup.subtree_control" while ->child_ss_mask is the effective |
382 | * one which may have more subsystems enabled. Controller knobs |
383 | * are made available iff it's enabled in ->subtree_control. |
384 | */ |
385 | u16 subtree_control; |
386 | u16 subtree_ss_mask; |
387 | u16 old_subtree_control; |
388 | u16 old_subtree_ss_mask; |
389 | |
390 | /* Private pointers for each registered subsystem */ |
391 | struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT]; |
392 | |
393 | struct cgroup_root *root; |
394 | |
395 | /* |
396 | * List of cgrp_cset_links pointing at css_sets with tasks in this |
397 | * cgroup. Protected by css_set_lock. |
398 | */ |
399 | struct list_head cset_links; |
400 | |
401 | /* |
402 | * On the default hierarchy, a css_set for a cgroup with some |
403 | * susbsys disabled will point to css's which are associated with |
404 | * the closest ancestor which has the subsys enabled. The |
405 | * following lists all css_sets which point to this cgroup's css |
406 | * for the given subsystem. |
407 | */ |
408 | struct list_head e_csets[CGROUP_SUBSYS_COUNT]; |
409 | |
410 | /* |
411 | * If !threaded, self. If threaded, it points to the nearest |
412 | * domain ancestor. Inside a threaded subtree, cgroups are exempt |
413 | * from process granularity and no-internal-task constraint. |
414 | * Domain level resource consumptions which aren't tied to a |
415 | * specific task are charged to the dom_cgrp. |
416 | */ |
417 | struct cgroup *dom_cgrp; |
418 | struct cgroup *old_dom_cgrp; /* used while enabling threaded */ |
419 | |
420 | /* per-cpu recursive resource statistics */ |
421 | struct cgroup_rstat_cpu __percpu *rstat_cpu; |
422 | struct list_head rstat_css_list; |
423 | |
424 | /* cgroup basic resource statistics */ |
425 | struct cgroup_base_stat pending_bstat; /* pending from children */ |
426 | struct cgroup_base_stat bstat; |
427 | struct prev_cputime prev_cputime; /* for printing out cputime */ |
428 | |
429 | /* |
430 | * list of pidlists, up to two for each namespace (one for procs, one |
431 | * for tasks); created on demand. |
432 | */ |
433 | struct list_head pidlists; |
434 | struct mutex pidlist_mutex; |
435 | |
436 | /* used to wait for offlining of csses */ |
437 | wait_queue_head_t offline_waitq; |
438 | |
439 | /* used to schedule release agent */ |
440 | struct work_struct release_agent_work; |
441 | |
442 | /* used to track pressure stalls */ |
443 | struct psi_group psi; |
444 | |
445 | /* used to store eBPF programs */ |
446 | struct cgroup_bpf bpf; |
447 | |
448 | /* If there is block congestion on this cgroup. */ |
449 | atomic_t congestion_count; |
450 | |
451 | /* ids of the ancestors at each level including self */ |
452 | int ancestor_ids[]; |
453 | }; |
454 | |
455 | /* |
456 | * A cgroup_root represents the root of a cgroup hierarchy, and may be |
457 | * associated with a kernfs_root to form an active hierarchy. This is |
458 | * internal to cgroup core. Don't access directly from controllers. |
459 | */ |
460 | struct cgroup_root { |
461 | struct kernfs_root *kf_root; |
462 | |
463 | /* The bitmask of subsystems attached to this hierarchy */ |
464 | unsigned int subsys_mask; |
465 | |
466 | /* Unique id for this hierarchy. */ |
467 | int hierarchy_id; |
468 | |
469 | /* The root cgroup. Root is destroyed on its release. */ |
470 | struct cgroup cgrp; |
471 | |
472 | /* for cgrp->ancestor_ids[0] */ |
473 | int cgrp_ancestor_id_storage; |
474 | |
475 | /* Number of cgroups in the hierarchy, used only for /proc/cgroups */ |
476 | atomic_t nr_cgrps; |
477 | |
478 | /* A list running through the active hierarchies */ |
479 | struct list_head root_list; |
480 | |
481 | /* Hierarchy-specific flags */ |
482 | unsigned int flags; |
483 | |
484 | /* IDs for cgroups in this hierarchy */ |
485 | struct idr cgroup_idr; |
486 | |
487 | /* The path to use for release notifications. */ |
488 | char release_agent_path[PATH_MAX]; |
489 | |
490 | /* The name for this hierarchy - may be empty */ |
491 | char name[MAX_CGROUP_ROOT_NAMELEN]; |
492 | }; |
493 | |
494 | /* |
495 | * struct cftype: handler definitions for cgroup control files |
496 | * |
497 | * When reading/writing to a file: |
498 | * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata |
499 | * - the 'cftype' of the file is file->f_path.dentry->d_fsdata |
500 | */ |
501 | struct cftype { |
502 | /* |
503 | * By convention, the name should begin with the name of the |
504 | * subsystem, followed by a period. Zero length string indicates |
505 | * end of cftype array. |
506 | */ |
507 | char name[MAX_CFTYPE_NAME]; |
508 | unsigned long private; |
509 | |
510 | /* |
511 | * The maximum length of string, excluding trailing nul, that can |
512 | * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed. |
513 | */ |
514 | size_t max_write_len; |
515 | |
516 | /* CFTYPE_* flags */ |
517 | unsigned int flags; |
518 | |
519 | /* |
520 | * If non-zero, should contain the offset from the start of css to |
521 | * a struct cgroup_file field. cgroup will record the handle of |
522 | * the created file into it. The recorded handle can be used as |
523 | * long as the containing css remains accessible. |
524 | */ |
525 | unsigned int file_offset; |
526 | |
527 | /* |
528 | * Fields used for internal bookkeeping. Initialized automatically |
529 | * during registration. |
530 | */ |
531 | struct cgroup_subsys *ss; /* NULL for cgroup core files */ |
532 | struct list_head node; /* anchored at ss->cfts */ |
533 | struct kernfs_ops *kf_ops; |
534 | |
535 | int (*open)(struct kernfs_open_file *of); |
536 | void (*release)(struct kernfs_open_file *of); |
537 | |
538 | /* |
539 | * read_u64() is a shortcut for the common case of returning a |
540 | * single integer. Use it in place of read() |
541 | */ |
542 | u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft); |
543 | /* |
544 | * read_s64() is a signed version of read_u64() |
545 | */ |
546 | s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft); |
547 | |
548 | /* generic seq_file read interface */ |
549 | int (*seq_show)(struct seq_file *sf, void *v); |
550 | |
551 | /* optional ops, implement all or none */ |
552 | void *(*seq_start)(struct seq_file *sf, loff_t *ppos); |
553 | void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); |
554 | void (*seq_stop)(struct seq_file *sf, void *v); |
555 | |
556 | /* |
557 | * write_u64() is a shortcut for the common case of accepting |
558 | * a single integer (as parsed by simple_strtoull) from |
559 | * userspace. Use in place of write(); return 0 or error. |
560 | */ |
561 | int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft, |
562 | u64 val); |
563 | /* |
564 | * write_s64() is a signed version of write_u64() |
565 | */ |
566 | int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft, |
567 | s64 val); |
568 | |
569 | /* |
570 | * write() is the generic write callback which maps directly to |
571 | * kernfs write operation and overrides all other operations. |
572 | * Maximum write size is determined by ->max_write_len. Use |
573 | * of_css/cft() to access the associated css and cft. |
574 | */ |
575 | ssize_t (*write)(struct kernfs_open_file *of, |
576 | char *buf, size_t nbytes, loff_t off); |
577 | |
578 | __poll_t (*poll)(struct kernfs_open_file *of, |
579 | struct poll_table_struct *pt); |
580 | |
581 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
582 | struct lock_class_key lockdep_key; |
583 | #endif |
584 | }; |
585 | |
586 | /* |
587 | * Control Group subsystem type. |
588 | * See Documentation/cgroup-v1/cgroups.txt for details |
589 | */ |
590 | struct cgroup_subsys { |
591 | struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css); |
592 | int (*css_online)(struct cgroup_subsys_state *css); |
593 | void (*css_offline)(struct cgroup_subsys_state *css); |
594 | void (*css_released)(struct cgroup_subsys_state *css); |
595 | void (*css_free)(struct cgroup_subsys_state *css); |
596 | void (*css_reset)(struct cgroup_subsys_state *css); |
597 | void (*css_rstat_flush)(struct cgroup_subsys_state *css, int cpu); |
598 | int (*)(struct seq_file *seq, |
599 | struct cgroup_subsys_state *css); |
600 | |
601 | int (*can_attach)(struct cgroup_taskset *tset); |
602 | void (*cancel_attach)(struct cgroup_taskset *tset); |
603 | void (*attach)(struct cgroup_taskset *tset); |
604 | void (*post_attach)(void); |
605 | int (*can_fork)(struct task_struct *task); |
606 | void (*cancel_fork)(struct task_struct *task); |
607 | void (*fork)(struct task_struct *task); |
608 | void (*exit)(struct task_struct *task); |
609 | void (*release)(struct task_struct *task); |
610 | void (*bind)(struct cgroup_subsys_state *root_css); |
611 | |
612 | bool early_init:1; |
613 | |
614 | /* |
615 | * If %true, the controller, on the default hierarchy, doesn't show |
616 | * up in "cgroup.controllers" or "cgroup.subtree_control", is |
617 | * implicitly enabled on all cgroups on the default hierarchy, and |
618 | * bypasses the "no internal process" constraint. This is for |
619 | * utility type controllers which is transparent to userland. |
620 | * |
621 | * An implicit controller can be stolen from the default hierarchy |
622 | * anytime and thus must be okay with offline csses from previous |
623 | * hierarchies coexisting with csses for the current one. |
624 | */ |
625 | bool implicit_on_dfl:1; |
626 | |
627 | /* |
628 | * If %true, the controller, supports threaded mode on the default |
629 | * hierarchy. In a threaded subtree, both process granularity and |
630 | * no-internal-process constraint are ignored and a threaded |
631 | * controllers should be able to handle that. |
632 | * |
633 | * Note that as an implicit controller is automatically enabled on |
634 | * all cgroups on the default hierarchy, it should also be |
635 | * threaded. implicit && !threaded is not supported. |
636 | */ |
637 | bool threaded:1; |
638 | |
639 | /* |
640 | * If %false, this subsystem is properly hierarchical - |
641 | * configuration, resource accounting and restriction on a parent |
642 | * cgroup cover those of its children. If %true, hierarchy support |
643 | * is broken in some ways - some subsystems ignore hierarchy |
644 | * completely while others are only implemented half-way. |
645 | * |
646 | * It's now disallowed to create nested cgroups if the subsystem is |
647 | * broken and cgroup core will emit a warning message on such |
648 | * cases. Eventually, all subsystems will be made properly |
649 | * hierarchical and this will go away. |
650 | */ |
651 | bool broken_hierarchy:1; |
652 | bool warned_broken_hierarchy:1; |
653 | |
654 | /* the following two fields are initialized automtically during boot */ |
655 | int id; |
656 | const char *name; |
657 | |
658 | /* optional, initialized automatically during boot if not set */ |
659 | const char *legacy_name; |
660 | |
661 | /* link to parent, protected by cgroup_lock() */ |
662 | struct cgroup_root *root; |
663 | |
664 | /* idr for css->id */ |
665 | struct idr css_idr; |
666 | |
667 | /* |
668 | * List of cftypes. Each entry is the first entry of an array |
669 | * terminated by zero length name. |
670 | */ |
671 | struct list_head cfts; |
672 | |
673 | /* |
674 | * Base cftypes which are automatically registered. The two can |
675 | * point to the same array. |
676 | */ |
677 | struct cftype *dfl_cftypes; /* for the default hierarchy */ |
678 | struct cftype *legacy_cftypes; /* for the legacy hierarchies */ |
679 | |
680 | /* |
681 | * A subsystem may depend on other subsystems. When such subsystem |
682 | * is enabled on a cgroup, the depended-upon subsystems are enabled |
683 | * together if available. Subsystems enabled due to dependency are |
684 | * not visible to userland until explicitly enabled. The following |
685 | * specifies the mask of subsystems that this one depends on. |
686 | */ |
687 | unsigned int depends_on; |
688 | }; |
689 | |
690 | extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
691 | |
692 | /** |
693 | * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups |
694 | * @tsk: target task |
695 | * |
696 | * Allows cgroup operations to synchronize against threadgroup changes |
697 | * using a percpu_rw_semaphore. |
698 | */ |
699 | static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) |
700 | { |
701 | percpu_down_read(&cgroup_threadgroup_rwsem); |
702 | } |
703 | |
704 | /** |
705 | * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups |
706 | * @tsk: target task |
707 | * |
708 | * Counterpart of cgroup_threadcgroup_change_begin(). |
709 | */ |
710 | static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) |
711 | { |
712 | percpu_up_read(&cgroup_threadgroup_rwsem); |
713 | } |
714 | |
715 | #else /* CONFIG_CGROUPS */ |
716 | |
717 | #define CGROUP_SUBSYS_COUNT 0 |
718 | |
719 | static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) |
720 | { |
721 | might_sleep(); |
722 | } |
723 | |
724 | static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {} |
725 | |
726 | #endif /* CONFIG_CGROUPS */ |
727 | |
728 | #ifdef CONFIG_SOCK_CGROUP_DATA |
729 | |
730 | /* |
731 | * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains |
732 | * per-socket cgroup information except for memcg association. |
733 | * |
734 | * On legacy hierarchies, net_prio and net_cls controllers directly set |
735 | * attributes on each sock which can then be tested by the network layer. |
736 | * On the default hierarchy, each sock is associated with the cgroup it was |
737 | * created in and the networking layer can match the cgroup directly. |
738 | * |
739 | * To avoid carrying all three cgroup related fields separately in sock, |
740 | * sock_cgroup_data overloads (prioidx, classid) and the cgroup pointer. |
741 | * On boot, sock_cgroup_data records the cgroup that the sock was created |
742 | * in so that cgroup2 matches can be made; however, once either net_prio or |
743 | * net_cls starts being used, the area is overriden to carry prioidx and/or |
744 | * classid. The two modes are distinguished by whether the lowest bit is |
745 | * set. Clear bit indicates cgroup pointer while set bit prioidx and |
746 | * classid. |
747 | * |
748 | * While userland may start using net_prio or net_cls at any time, once |
749 | * either is used, cgroup2 matching no longer works. There is no reason to |
750 | * mix the two and this is in line with how legacy and v2 compatibility is |
751 | * handled. On mode switch, cgroup references which are already being |
752 | * pointed to by socks may be leaked. While this can be remedied by adding |
753 | * synchronization around sock_cgroup_data, given that the number of leaked |
754 | * cgroups is bound and highly unlikely to be high, this seems to be the |
755 | * better trade-off. |
756 | */ |
757 | struct sock_cgroup_data { |
758 | union { |
759 | #ifdef __LITTLE_ENDIAN |
760 | struct { |
761 | u8 is_data; |
762 | u8 padding; |
763 | u16 prioidx; |
764 | u32 classid; |
765 | } __packed; |
766 | #else |
767 | struct { |
768 | u32 classid; |
769 | u16 prioidx; |
770 | u8 padding; |
771 | u8 is_data; |
772 | } __packed; |
773 | #endif |
774 | u64 val; |
775 | }; |
776 | }; |
777 | |
778 | /* |
779 | * There's a theoretical window where the following accessors race with |
780 | * updaters and return part of the previous pointer as the prioidx or |
781 | * classid. Such races are short-lived and the result isn't critical. |
782 | */ |
783 | static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd) |
784 | { |
785 | /* fallback to 1 which is always the ID of the root cgroup */ |
786 | return (skcd->is_data & 1) ? skcd->prioidx : 1; |
787 | } |
788 | |
789 | static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd) |
790 | { |
791 | /* fallback to 0 which is the unconfigured default classid */ |
792 | return (skcd->is_data & 1) ? skcd->classid : 0; |
793 | } |
794 | |
795 | /* |
796 | * If invoked concurrently, the updaters may clobber each other. The |
797 | * caller is responsible for synchronization. |
798 | */ |
799 | static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd, |
800 | u16 prioidx) |
801 | { |
802 | struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; |
803 | |
804 | if (sock_cgroup_prioidx(&skcd_buf) == prioidx) |
805 | return; |
806 | |
807 | if (!(skcd_buf.is_data & 1)) { |
808 | skcd_buf.val = 0; |
809 | skcd_buf.is_data = 1; |
810 | } |
811 | |
812 | skcd_buf.prioidx = prioidx; |
813 | WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ |
814 | } |
815 | |
816 | static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd, |
817 | u32 classid) |
818 | { |
819 | struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; |
820 | |
821 | if (sock_cgroup_classid(&skcd_buf) == classid) |
822 | return; |
823 | |
824 | if (!(skcd_buf.is_data & 1)) { |
825 | skcd_buf.val = 0; |
826 | skcd_buf.is_data = 1; |
827 | } |
828 | |
829 | skcd_buf.classid = classid; |
830 | WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ |
831 | } |
832 | |
833 | #else /* CONFIG_SOCK_CGROUP_DATA */ |
834 | |
835 | struct sock_cgroup_data { |
836 | }; |
837 | |
838 | #endif /* CONFIG_SOCK_CGROUP_DATA */ |
839 | |
840 | #endif /* _LINUX_CGROUP_DEFS_H */ |
841 | |