1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Generic helpers for smp ipi calls |
4 | * |
5 | * (C) Jens Axboe <jens.axboe@oracle.com> 2008 |
6 | */ |
7 | |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | |
10 | #include <linux/irq_work.h> |
11 | #include <linux/rcupdate.h> |
12 | #include <linux/rculist.h> |
13 | #include <linux/kernel.h> |
14 | #include <linux/export.h> |
15 | #include <linux/percpu.h> |
16 | #include <linux/init.h> |
17 | #include <linux/interrupt.h> |
18 | #include <linux/gfp.h> |
19 | #include <linux/smp.h> |
20 | #include <linux/cpu.h> |
21 | #include <linux/sched.h> |
22 | #include <linux/sched/idle.h> |
23 | #include <linux/hypervisor.h> |
24 | #include <linux/sched/clock.h> |
25 | #include <linux/nmi.h> |
26 | #include <linux/sched/debug.h> |
27 | #include <linux/jump_label.h> |
28 | |
29 | #include <trace/events/ipi.h> |
30 | #define CREATE_TRACE_POINTS |
31 | #include <trace/events/csd.h> |
32 | #undef CREATE_TRACE_POINTS |
33 | |
34 | #include "smpboot.h" |
35 | #include "sched/smp.h" |
36 | |
37 | #define CSD_TYPE(_csd) ((_csd)->node.u_flags & CSD_FLAG_TYPE_MASK) |
38 | |
39 | struct call_function_data { |
40 | call_single_data_t __percpu *csd; |
41 | cpumask_var_t cpumask; |
42 | cpumask_var_t cpumask_ipi; |
43 | }; |
44 | |
45 | static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data); |
46 | |
47 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); |
48 | |
49 | static DEFINE_PER_CPU(atomic_t, trigger_backtrace) = ATOMIC_INIT(1); |
50 | |
51 | static void __flush_smp_call_function_queue(bool warn_cpu_offline); |
52 | |
53 | int smpcfd_prepare_cpu(unsigned int cpu) |
54 | { |
55 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); |
56 | |
57 | if (!zalloc_cpumask_var_node(mask: &cfd->cpumask, GFP_KERNEL, |
58 | cpu_to_node(cpu))) |
59 | return -ENOMEM; |
60 | if (!zalloc_cpumask_var_node(mask: &cfd->cpumask_ipi, GFP_KERNEL, |
61 | cpu_to_node(cpu))) { |
62 | free_cpumask_var(mask: cfd->cpumask); |
63 | return -ENOMEM; |
64 | } |
65 | cfd->csd = alloc_percpu(call_single_data_t); |
66 | if (!cfd->csd) { |
67 | free_cpumask_var(mask: cfd->cpumask); |
68 | free_cpumask_var(mask: cfd->cpumask_ipi); |
69 | return -ENOMEM; |
70 | } |
71 | |
72 | return 0; |
73 | } |
74 | |
75 | int smpcfd_dead_cpu(unsigned int cpu) |
76 | { |
77 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); |
78 | |
79 | free_cpumask_var(mask: cfd->cpumask); |
80 | free_cpumask_var(mask: cfd->cpumask_ipi); |
81 | free_percpu(pdata: cfd->csd); |
82 | return 0; |
83 | } |
84 | |
85 | int smpcfd_dying_cpu(unsigned int cpu) |
86 | { |
87 | /* |
88 | * The IPIs for the smp-call-function callbacks queued by other |
89 | * CPUs might arrive late, either due to hardware latencies or |
90 | * because this CPU disabled interrupts (inside stop-machine) |
91 | * before the IPIs were sent. So flush out any pending callbacks |
92 | * explicitly (without waiting for the IPIs to arrive), to |
93 | * ensure that the outgoing CPU doesn't go offline with work |
94 | * still pending. |
95 | */ |
96 | __flush_smp_call_function_queue(warn_cpu_offline: false); |
97 | irq_work_run(); |
98 | return 0; |
99 | } |
100 | |
101 | void __init call_function_init(void) |
102 | { |
103 | int i; |
104 | |
105 | for_each_possible_cpu(i) |
106 | init_llist_head(list: &per_cpu(call_single_queue, i)); |
107 | |
108 | smpcfd_prepare_cpu(smp_processor_id()); |
109 | } |
110 | |
111 | static __always_inline void |
112 | send_call_function_single_ipi(int cpu) |
113 | { |
114 | if (call_function_single_prep_ipi(cpu)) { |
115 | trace_ipi_send_cpu(cpu, _RET_IP_, |
116 | callback: generic_smp_call_function_single_interrupt); |
117 | arch_send_call_function_single_ipi(cpu); |
118 | } |
119 | } |
120 | |
121 | static __always_inline void |
122 | send_call_function_ipi_mask(struct cpumask *mask) |
123 | { |
124 | trace_ipi_send_cpumask(cpumask: mask, _RET_IP_, |
125 | callback: generic_smp_call_function_single_interrupt); |
126 | arch_send_call_function_ipi_mask(mask); |
127 | } |
128 | |
129 | static __always_inline void |
130 | csd_do_func(smp_call_func_t func, void *info, call_single_data_t *csd) |
131 | { |
132 | trace_csd_function_entry(func, csd); |
133 | func(info); |
134 | trace_csd_function_exit(func, csd); |
135 | } |
136 | |
137 | #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG |
138 | |
139 | static DEFINE_STATIC_KEY_MAYBE(CONFIG_CSD_LOCK_WAIT_DEBUG_DEFAULT, csdlock_debug_enabled); |
140 | |
141 | /* |
142 | * Parse the csdlock_debug= kernel boot parameter. |
143 | * |
144 | * If you need to restore the old "ext" value that once provided |
145 | * additional debugging information, reapply the following commits: |
146 | * |
147 | * de7b09ef658d ("locking/csd_lock: Prepare more CSD lock debugging") |
148 | * a5aabace5fb8 ("locking/csd_lock: Add more data to CSD lock debugging") |
149 | */ |
150 | static int __init csdlock_debug(char *str) |
151 | { |
152 | int ret; |
153 | unsigned int val = 0; |
154 | |
155 | ret = get_option(str: &str, pint: &val); |
156 | if (ret) { |
157 | if (val) |
158 | static_branch_enable(&csdlock_debug_enabled); |
159 | else |
160 | static_branch_disable(&csdlock_debug_enabled); |
161 | } |
162 | |
163 | return 1; |
164 | } |
165 | __setup("csdlock_debug=" , csdlock_debug); |
166 | |
167 | static DEFINE_PER_CPU(call_single_data_t *, cur_csd); |
168 | static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func); |
169 | static DEFINE_PER_CPU(void *, cur_csd_info); |
170 | |
171 | static ulong csd_lock_timeout = 5000; /* CSD lock timeout in milliseconds. */ |
172 | module_param(csd_lock_timeout, ulong, 0444); |
173 | static int panic_on_ipistall; /* CSD panic timeout in milliseconds, 300000 for five minutes. */ |
174 | module_param(panic_on_ipistall, int, 0444); |
175 | |
176 | static atomic_t csd_bug_count = ATOMIC_INIT(0); |
177 | |
178 | /* Record current CSD work for current CPU, NULL to erase. */ |
179 | static void __csd_lock_record(call_single_data_t *csd) |
180 | { |
181 | if (!csd) { |
182 | smp_mb(); /* NULL cur_csd after unlock. */ |
183 | __this_cpu_write(cur_csd, NULL); |
184 | return; |
185 | } |
186 | __this_cpu_write(cur_csd_func, csd->func); |
187 | __this_cpu_write(cur_csd_info, csd->info); |
188 | smp_wmb(); /* func and info before csd. */ |
189 | __this_cpu_write(cur_csd, csd); |
190 | smp_mb(); /* Update cur_csd before function call. */ |
191 | /* Or before unlock, as the case may be. */ |
192 | } |
193 | |
194 | static __always_inline void csd_lock_record(call_single_data_t *csd) |
195 | { |
196 | if (static_branch_unlikely(&csdlock_debug_enabled)) |
197 | __csd_lock_record(csd); |
198 | } |
199 | |
200 | static int csd_lock_wait_getcpu(call_single_data_t *csd) |
201 | { |
202 | unsigned int csd_type; |
203 | |
204 | csd_type = CSD_TYPE(csd); |
205 | if (csd_type == CSD_TYPE_ASYNC || csd_type == CSD_TYPE_SYNC) |
206 | return csd->node.dst; /* Other CSD_TYPE_ values might not have ->dst. */ |
207 | return -1; |
208 | } |
209 | |
210 | /* |
211 | * Complain if too much time spent waiting. Note that only |
212 | * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU, |
213 | * so waiting on other types gets much less information. |
214 | */ |
215 | static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id) |
216 | { |
217 | int cpu = -1; |
218 | int cpux; |
219 | bool firsttime; |
220 | u64 ts2, ts_delta; |
221 | call_single_data_t *cpu_cur_csd; |
222 | unsigned int flags = READ_ONCE(csd->node.u_flags); |
223 | unsigned long long csd_lock_timeout_ns = csd_lock_timeout * NSEC_PER_MSEC; |
224 | |
225 | if (!(flags & CSD_FLAG_LOCK)) { |
226 | if (!unlikely(*bug_id)) |
227 | return true; |
228 | cpu = csd_lock_wait_getcpu(csd); |
229 | pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n" , |
230 | *bug_id, raw_smp_processor_id(), cpu); |
231 | return true; |
232 | } |
233 | |
234 | ts2 = sched_clock(); |
235 | /* How long since we last checked for a stuck CSD lock.*/ |
236 | ts_delta = ts2 - *ts1; |
237 | if (likely(ts_delta <= csd_lock_timeout_ns || csd_lock_timeout_ns == 0)) |
238 | return false; |
239 | |
240 | firsttime = !*bug_id; |
241 | if (firsttime) |
242 | *bug_id = atomic_inc_return(v: &csd_bug_count); |
243 | cpu = csd_lock_wait_getcpu(csd); |
244 | if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n" , __func__, cpu)) |
245 | cpux = 0; |
246 | else |
247 | cpux = cpu; |
248 | cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */ |
249 | /* How long since this CSD lock was stuck. */ |
250 | ts_delta = ts2 - ts0; |
251 | pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %llu ns for CPU#%02d %pS(%ps).\n" , |
252 | firsttime ? "Detected" : "Continued" , *bug_id, raw_smp_processor_id(), ts_delta, |
253 | cpu, csd->func, csd->info); |
254 | /* |
255 | * If the CSD lock is still stuck after 5 minutes, it is unlikely |
256 | * to become unstuck. Use a signed comparison to avoid triggering |
257 | * on underflows when the TSC is out of sync between sockets. |
258 | */ |
259 | BUG_ON(panic_on_ipistall > 0 && (s64)ts_delta > ((s64)panic_on_ipistall * NSEC_PER_MSEC)); |
260 | if (cpu_cur_csd && csd != cpu_cur_csd) { |
261 | pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n" , |
262 | *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)), |
263 | READ_ONCE(per_cpu(cur_csd_info, cpux))); |
264 | } else { |
265 | pr_alert("\tcsd: CSD lock (#%d) %s.\n" , |
266 | *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request" ); |
267 | } |
268 | if (cpu >= 0) { |
269 | if (atomic_cmpxchg_acquire(v: &per_cpu(trigger_backtrace, cpu), old: 1, new: 0)) |
270 | dump_cpu_task(cpu); |
271 | if (!cpu_cur_csd) { |
272 | pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n" , *bug_id, raw_smp_processor_id(), cpu); |
273 | arch_send_call_function_single_ipi(cpu); |
274 | } |
275 | } |
276 | if (firsttime) |
277 | dump_stack(); |
278 | *ts1 = ts2; |
279 | |
280 | return false; |
281 | } |
282 | |
283 | /* |
284 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources |
285 | * |
286 | * For non-synchronous ipi calls the csd can still be in use by the |
287 | * previous function call. For multi-cpu calls its even more interesting |
288 | * as we'll have to ensure no other cpu is observing our csd. |
289 | */ |
290 | static void __csd_lock_wait(call_single_data_t *csd) |
291 | { |
292 | int bug_id = 0; |
293 | u64 ts0, ts1; |
294 | |
295 | ts1 = ts0 = sched_clock(); |
296 | for (;;) { |
297 | if (csd_lock_wait_toolong(csd, ts0, ts1: &ts1, bug_id: &bug_id)) |
298 | break; |
299 | cpu_relax(); |
300 | } |
301 | smp_acquire__after_ctrl_dep(); |
302 | } |
303 | |
304 | static __always_inline void csd_lock_wait(call_single_data_t *csd) |
305 | { |
306 | if (static_branch_unlikely(&csdlock_debug_enabled)) { |
307 | __csd_lock_wait(csd); |
308 | return; |
309 | } |
310 | |
311 | smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK)); |
312 | } |
313 | #else |
314 | static void csd_lock_record(call_single_data_t *csd) |
315 | { |
316 | } |
317 | |
318 | static __always_inline void csd_lock_wait(call_single_data_t *csd) |
319 | { |
320 | smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK)); |
321 | } |
322 | #endif |
323 | |
324 | static __always_inline void csd_lock(call_single_data_t *csd) |
325 | { |
326 | csd_lock_wait(csd); |
327 | csd->node.u_flags |= CSD_FLAG_LOCK; |
328 | |
329 | /* |
330 | * prevent CPU from reordering the above assignment |
331 | * to ->flags with any subsequent assignments to other |
332 | * fields of the specified call_single_data_t structure: |
333 | */ |
334 | smp_wmb(); |
335 | } |
336 | |
337 | static __always_inline void csd_unlock(call_single_data_t *csd) |
338 | { |
339 | WARN_ON(!(csd->node.u_flags & CSD_FLAG_LOCK)); |
340 | |
341 | /* |
342 | * ensure we're all done before releasing data: |
343 | */ |
344 | smp_store_release(&csd->node.u_flags, 0); |
345 | } |
346 | |
347 | static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data); |
348 | |
349 | void __smp_call_single_queue(int cpu, struct llist_node *node) |
350 | { |
351 | /* |
352 | * We have to check the type of the CSD before queueing it, because |
353 | * once queued it can have its flags cleared by |
354 | * flush_smp_call_function_queue() |
355 | * even if we haven't sent the smp_call IPI yet (e.g. the stopper |
356 | * executes migration_cpu_stop() on the remote CPU). |
357 | */ |
358 | if (trace_csd_queue_cpu_enabled()) { |
359 | call_single_data_t *csd; |
360 | smp_call_func_t func; |
361 | |
362 | csd = container_of(node, call_single_data_t, node.llist); |
363 | func = CSD_TYPE(csd) == CSD_TYPE_TTWU ? |
364 | sched_ttwu_pending : csd->func; |
365 | |
366 | trace_csd_queue_cpu(cpu, _RET_IP_, func, csd); |
367 | } |
368 | |
369 | /* |
370 | * The list addition should be visible to the target CPU when it pops |
371 | * the head of the list to pull the entry off it in the IPI handler |
372 | * because of normal cache coherency rules implied by the underlying |
373 | * llist ops. |
374 | * |
375 | * If IPIs can go out of order to the cache coherency protocol |
376 | * in an architecture, sufficient synchronisation should be added |
377 | * to arch code to make it appear to obey cache coherency WRT |
378 | * locking and barrier primitives. Generic code isn't really |
379 | * equipped to do the right thing... |
380 | */ |
381 | if (llist_add(new: node, head: &per_cpu(call_single_queue, cpu))) |
382 | send_call_function_single_ipi(cpu); |
383 | } |
384 | |
385 | /* |
386 | * Insert a previously allocated call_single_data_t element |
387 | * for execution on the given CPU. data must already have |
388 | * ->func, ->info, and ->flags set. |
389 | */ |
390 | static int generic_exec_single(int cpu, call_single_data_t *csd) |
391 | { |
392 | if (cpu == smp_processor_id()) { |
393 | smp_call_func_t func = csd->func; |
394 | void *info = csd->info; |
395 | unsigned long flags; |
396 | |
397 | /* |
398 | * We can unlock early even for the synchronous on-stack case, |
399 | * since we're doing this from the same CPU.. |
400 | */ |
401 | csd_lock_record(csd); |
402 | csd_unlock(csd); |
403 | local_irq_save(flags); |
404 | csd_do_func(func, info, NULL); |
405 | csd_lock_record(NULL); |
406 | local_irq_restore(flags); |
407 | return 0; |
408 | } |
409 | |
410 | if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) { |
411 | csd_unlock(csd); |
412 | return -ENXIO; |
413 | } |
414 | |
415 | __smp_call_single_queue(cpu, node: &csd->node.llist); |
416 | |
417 | return 0; |
418 | } |
419 | |
420 | /** |
421 | * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks |
422 | * |
423 | * Invoked by arch to handle an IPI for call function single. |
424 | * Must be called with interrupts disabled. |
425 | */ |
426 | void generic_smp_call_function_single_interrupt(void) |
427 | { |
428 | __flush_smp_call_function_queue(warn_cpu_offline: true); |
429 | } |
430 | |
431 | /** |
432 | * __flush_smp_call_function_queue - Flush pending smp-call-function callbacks |
433 | * |
434 | * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an |
435 | * offline CPU. Skip this check if set to 'false'. |
436 | * |
437 | * Flush any pending smp-call-function callbacks queued on this CPU. This is |
438 | * invoked by the generic IPI handler, as well as by a CPU about to go offline, |
439 | * to ensure that all pending IPI callbacks are run before it goes completely |
440 | * offline. |
441 | * |
442 | * Loop through the call_single_queue and run all the queued callbacks. |
443 | * Must be called with interrupts disabled. |
444 | */ |
445 | static void __flush_smp_call_function_queue(bool warn_cpu_offline) |
446 | { |
447 | call_single_data_t *csd, *csd_next; |
448 | struct llist_node *entry, *prev; |
449 | struct llist_head *head; |
450 | static bool warned; |
451 | atomic_t *tbt; |
452 | |
453 | lockdep_assert_irqs_disabled(); |
454 | |
455 | /* Allow waiters to send backtrace NMI from here onwards */ |
456 | tbt = this_cpu_ptr(&trigger_backtrace); |
457 | atomic_set_release(v: tbt, i: 1); |
458 | |
459 | head = this_cpu_ptr(&call_single_queue); |
460 | entry = llist_del_all(head); |
461 | entry = llist_reverse_order(head: entry); |
462 | |
463 | /* There shouldn't be any pending callbacks on an offline CPU. */ |
464 | if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) && |
465 | !warned && entry != NULL)) { |
466 | warned = true; |
467 | WARN(1, "IPI on offline CPU %d\n" , smp_processor_id()); |
468 | |
469 | /* |
470 | * We don't have to use the _safe() variant here |
471 | * because we are not invoking the IPI handlers yet. |
472 | */ |
473 | llist_for_each_entry(csd, entry, node.llist) { |
474 | switch (CSD_TYPE(csd)) { |
475 | case CSD_TYPE_ASYNC: |
476 | case CSD_TYPE_SYNC: |
477 | case CSD_TYPE_IRQ_WORK: |
478 | pr_warn("IPI callback %pS sent to offline CPU\n" , |
479 | csd->func); |
480 | break; |
481 | |
482 | case CSD_TYPE_TTWU: |
483 | pr_warn("IPI task-wakeup sent to offline CPU\n" ); |
484 | break; |
485 | |
486 | default: |
487 | pr_warn("IPI callback, unknown type %d, sent to offline CPU\n" , |
488 | CSD_TYPE(csd)); |
489 | break; |
490 | } |
491 | } |
492 | } |
493 | |
494 | /* |
495 | * First; run all SYNC callbacks, people are waiting for us. |
496 | */ |
497 | prev = NULL; |
498 | llist_for_each_entry_safe(csd, csd_next, entry, node.llist) { |
499 | /* Do we wait until *after* callback? */ |
500 | if (CSD_TYPE(csd) == CSD_TYPE_SYNC) { |
501 | smp_call_func_t func = csd->func; |
502 | void *info = csd->info; |
503 | |
504 | if (prev) { |
505 | prev->next = &csd_next->node.llist; |
506 | } else { |
507 | entry = &csd_next->node.llist; |
508 | } |
509 | |
510 | csd_lock_record(csd); |
511 | csd_do_func(func, info, csd); |
512 | csd_unlock(csd); |
513 | csd_lock_record(NULL); |
514 | } else { |
515 | prev = &csd->node.llist; |
516 | } |
517 | } |
518 | |
519 | if (!entry) |
520 | return; |
521 | |
522 | /* |
523 | * Second; run all !SYNC callbacks. |
524 | */ |
525 | prev = NULL; |
526 | llist_for_each_entry_safe(csd, csd_next, entry, node.llist) { |
527 | int type = CSD_TYPE(csd); |
528 | |
529 | if (type != CSD_TYPE_TTWU) { |
530 | if (prev) { |
531 | prev->next = &csd_next->node.llist; |
532 | } else { |
533 | entry = &csd_next->node.llist; |
534 | } |
535 | |
536 | if (type == CSD_TYPE_ASYNC) { |
537 | smp_call_func_t func = csd->func; |
538 | void *info = csd->info; |
539 | |
540 | csd_lock_record(csd); |
541 | csd_unlock(csd); |
542 | csd_do_func(func, info, csd); |
543 | csd_lock_record(NULL); |
544 | } else if (type == CSD_TYPE_IRQ_WORK) { |
545 | irq_work_single(arg: csd); |
546 | } |
547 | |
548 | } else { |
549 | prev = &csd->node.llist; |
550 | } |
551 | } |
552 | |
553 | /* |
554 | * Third; only CSD_TYPE_TTWU is left, issue those. |
555 | */ |
556 | if (entry) { |
557 | csd = llist_entry(entry, typeof(*csd), node.llist); |
558 | csd_do_func(func: sched_ttwu_pending, info: entry, csd); |
559 | } |
560 | } |
561 | |
562 | |
563 | /** |
564 | * flush_smp_call_function_queue - Flush pending smp-call-function callbacks |
565 | * from task context (idle, migration thread) |
566 | * |
567 | * When TIF_POLLING_NRFLAG is supported and a CPU is in idle and has it |
568 | * set, then remote CPUs can avoid sending IPIs and wake the idle CPU by |
569 | * setting TIF_NEED_RESCHED. The idle task on the woken up CPU has to |
570 | * handle queued SMP function calls before scheduling. |
571 | * |
572 | * The migration thread has to ensure that an eventually pending wakeup has |
573 | * been handled before it migrates a task. |
574 | */ |
575 | void flush_smp_call_function_queue(void) |
576 | { |
577 | unsigned int was_pending; |
578 | unsigned long flags; |
579 | |
580 | if (llist_empty(this_cpu_ptr(&call_single_queue))) |
581 | return; |
582 | |
583 | local_irq_save(flags); |
584 | /* Get the already pending soft interrupts for RT enabled kernels */ |
585 | was_pending = local_softirq_pending(); |
586 | __flush_smp_call_function_queue(warn_cpu_offline: true); |
587 | if (local_softirq_pending()) |
588 | do_softirq_post_smp_call_flush(unused: was_pending); |
589 | |
590 | local_irq_restore(flags); |
591 | } |
592 | |
593 | /* |
594 | * smp_call_function_single - Run a function on a specific CPU |
595 | * @func: The function to run. This must be fast and non-blocking. |
596 | * @info: An arbitrary pointer to pass to the function. |
597 | * @wait: If true, wait until function has completed on other CPUs. |
598 | * |
599 | * Returns 0 on success, else a negative status code. |
600 | */ |
601 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info, |
602 | int wait) |
603 | { |
604 | call_single_data_t *csd; |
605 | call_single_data_t csd_stack = { |
606 | .node = { .u_flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC, }, |
607 | }; |
608 | int this_cpu; |
609 | int err; |
610 | |
611 | /* |
612 | * prevent preemption and reschedule on another processor, |
613 | * as well as CPU removal |
614 | */ |
615 | this_cpu = get_cpu(); |
616 | |
617 | /* |
618 | * Can deadlock when called with interrupts disabled. |
619 | * We allow cpu's that are not yet online though, as no one else can |
620 | * send smp call function interrupt to this cpu and as such deadlocks |
621 | * can't happen. |
622 | */ |
623 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() |
624 | && !oops_in_progress); |
625 | |
626 | /* |
627 | * When @wait we can deadlock when we interrupt between llist_add() and |
628 | * arch_send_call_function_ipi*(); when !@wait we can deadlock due to |
629 | * csd_lock() on because the interrupt context uses the same csd |
630 | * storage. |
631 | */ |
632 | WARN_ON_ONCE(!in_task()); |
633 | |
634 | csd = &csd_stack; |
635 | if (!wait) { |
636 | csd = this_cpu_ptr(&csd_data); |
637 | csd_lock(csd); |
638 | } |
639 | |
640 | csd->func = func; |
641 | csd->info = info; |
642 | #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG |
643 | csd->node.src = smp_processor_id(); |
644 | csd->node.dst = cpu; |
645 | #endif |
646 | |
647 | err = generic_exec_single(cpu, csd); |
648 | |
649 | if (wait) |
650 | csd_lock_wait(csd); |
651 | |
652 | put_cpu(); |
653 | |
654 | return err; |
655 | } |
656 | EXPORT_SYMBOL(smp_call_function_single); |
657 | |
658 | /** |
659 | * smp_call_function_single_async() - Run an asynchronous function on a |
660 | * specific CPU. |
661 | * @cpu: The CPU to run on. |
662 | * @csd: Pre-allocated and setup data structure |
663 | * |
664 | * Like smp_call_function_single(), but the call is asynchonous and |
665 | * can thus be done from contexts with disabled interrupts. |
666 | * |
667 | * The caller passes his own pre-allocated data structure |
668 | * (ie: embedded in an object) and is responsible for synchronizing it |
669 | * such that the IPIs performed on the @csd are strictly serialized. |
670 | * |
671 | * If the function is called with one csd which has not yet been |
672 | * processed by previous call to smp_call_function_single_async(), the |
673 | * function will return immediately with -EBUSY showing that the csd |
674 | * object is still in progress. |
675 | * |
676 | * NOTE: Be careful, there is unfortunately no current debugging facility to |
677 | * validate the correctness of this serialization. |
678 | * |
679 | * Return: %0 on success or negative errno value on error |
680 | */ |
681 | int smp_call_function_single_async(int cpu, call_single_data_t *csd) |
682 | { |
683 | int err = 0; |
684 | |
685 | preempt_disable(); |
686 | |
687 | if (csd->node.u_flags & CSD_FLAG_LOCK) { |
688 | err = -EBUSY; |
689 | goto out; |
690 | } |
691 | |
692 | csd->node.u_flags = CSD_FLAG_LOCK; |
693 | smp_wmb(); |
694 | |
695 | err = generic_exec_single(cpu, csd); |
696 | |
697 | out: |
698 | preempt_enable(); |
699 | |
700 | return err; |
701 | } |
702 | EXPORT_SYMBOL_GPL(smp_call_function_single_async); |
703 | |
704 | /* |
705 | * smp_call_function_any - Run a function on any of the given cpus |
706 | * @mask: The mask of cpus it can run on. |
707 | * @func: The function to run. This must be fast and non-blocking. |
708 | * @info: An arbitrary pointer to pass to the function. |
709 | * @wait: If true, wait until function has completed. |
710 | * |
711 | * Returns 0 on success, else a negative status code (if no cpus were online). |
712 | * |
713 | * Selection preference: |
714 | * 1) current cpu if in @mask |
715 | * 2) any cpu of current node if in @mask |
716 | * 3) any other online cpu in @mask |
717 | */ |
718 | int smp_call_function_any(const struct cpumask *mask, |
719 | smp_call_func_t func, void *info, int wait) |
720 | { |
721 | unsigned int cpu; |
722 | const struct cpumask *nodemask; |
723 | int ret; |
724 | |
725 | /* Try for same CPU (cheapest) */ |
726 | cpu = get_cpu(); |
727 | if (cpumask_test_cpu(cpu, cpumask: mask)) |
728 | goto call; |
729 | |
730 | /* Try for same node. */ |
731 | nodemask = cpumask_of_node(cpu_to_node(cpu)); |
732 | for (cpu = cpumask_first_and(srcp1: nodemask, srcp2: mask); cpu < nr_cpu_ids; |
733 | cpu = cpumask_next_and(n: cpu, src1p: nodemask, src2p: mask)) { |
734 | if (cpu_online(cpu)) |
735 | goto call; |
736 | } |
737 | |
738 | /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ |
739 | cpu = cpumask_any_and(mask, cpu_online_mask); |
740 | call: |
741 | ret = smp_call_function_single(cpu, func, info, wait); |
742 | put_cpu(); |
743 | return ret; |
744 | } |
745 | EXPORT_SYMBOL_GPL(smp_call_function_any); |
746 | |
747 | /* |
748 | * Flags to be used as scf_flags argument of smp_call_function_many_cond(). |
749 | * |
750 | * %SCF_WAIT: Wait until function execution is completed |
751 | * %SCF_RUN_LOCAL: Run also locally if local cpu is set in cpumask |
752 | */ |
753 | #define SCF_WAIT (1U << 0) |
754 | #define SCF_RUN_LOCAL (1U << 1) |
755 | |
756 | static void smp_call_function_many_cond(const struct cpumask *mask, |
757 | smp_call_func_t func, void *info, |
758 | unsigned int scf_flags, |
759 | smp_cond_func_t cond_func) |
760 | { |
761 | int cpu, last_cpu, this_cpu = smp_processor_id(); |
762 | struct call_function_data *cfd; |
763 | bool wait = scf_flags & SCF_WAIT; |
764 | int nr_cpus = 0; |
765 | bool run_remote = false; |
766 | bool run_local = false; |
767 | |
768 | lockdep_assert_preemption_disabled(); |
769 | |
770 | /* |
771 | * Can deadlock when called with interrupts disabled. |
772 | * We allow cpu's that are not yet online though, as no one else can |
773 | * send smp call function interrupt to this cpu and as such deadlocks |
774 | * can't happen. |
775 | */ |
776 | if (cpu_online(cpu: this_cpu) && !oops_in_progress && |
777 | !early_boot_irqs_disabled) |
778 | lockdep_assert_irqs_enabled(); |
779 | |
780 | /* |
781 | * When @wait we can deadlock when we interrupt between llist_add() and |
782 | * arch_send_call_function_ipi*(); when !@wait we can deadlock due to |
783 | * csd_lock() on because the interrupt context uses the same csd |
784 | * storage. |
785 | */ |
786 | WARN_ON_ONCE(!in_task()); |
787 | |
788 | /* Check if we need local execution. */ |
789 | if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(cpu: this_cpu, cpumask: mask)) |
790 | run_local = true; |
791 | |
792 | /* Check if we need remote execution, i.e., any CPU excluding this one. */ |
793 | cpu = cpumask_first_and(srcp1: mask, cpu_online_mask); |
794 | if (cpu == this_cpu) |
795 | cpu = cpumask_next_and(n: cpu, src1p: mask, cpu_online_mask); |
796 | if (cpu < nr_cpu_ids) |
797 | run_remote = true; |
798 | |
799 | if (run_remote) { |
800 | cfd = this_cpu_ptr(&cfd_data); |
801 | cpumask_and(dstp: cfd->cpumask, src1p: mask, cpu_online_mask); |
802 | __cpumask_clear_cpu(cpu: this_cpu, dstp: cfd->cpumask); |
803 | |
804 | cpumask_clear(dstp: cfd->cpumask_ipi); |
805 | for_each_cpu(cpu, cfd->cpumask) { |
806 | call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu); |
807 | |
808 | if (cond_func && !cond_func(cpu, info)) { |
809 | __cpumask_clear_cpu(cpu, dstp: cfd->cpumask); |
810 | continue; |
811 | } |
812 | |
813 | csd_lock(csd); |
814 | if (wait) |
815 | csd->node.u_flags |= CSD_TYPE_SYNC; |
816 | csd->func = func; |
817 | csd->info = info; |
818 | #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG |
819 | csd->node.src = smp_processor_id(); |
820 | csd->node.dst = cpu; |
821 | #endif |
822 | trace_csd_queue_cpu(cpu, _RET_IP_, func, csd); |
823 | |
824 | if (llist_add(new: &csd->node.llist, head: &per_cpu(call_single_queue, cpu))) { |
825 | __cpumask_set_cpu(cpu, dstp: cfd->cpumask_ipi); |
826 | nr_cpus++; |
827 | last_cpu = cpu; |
828 | } |
829 | } |
830 | |
831 | /* |
832 | * Choose the most efficient way to send an IPI. Note that the |
833 | * number of CPUs might be zero due to concurrent changes to the |
834 | * provided mask. |
835 | */ |
836 | if (nr_cpus == 1) |
837 | send_call_function_single_ipi(cpu: last_cpu); |
838 | else if (likely(nr_cpus > 1)) |
839 | send_call_function_ipi_mask(mask: cfd->cpumask_ipi); |
840 | } |
841 | |
842 | if (run_local && (!cond_func || cond_func(this_cpu, info))) { |
843 | unsigned long flags; |
844 | |
845 | local_irq_save(flags); |
846 | csd_do_func(func, info, NULL); |
847 | local_irq_restore(flags); |
848 | } |
849 | |
850 | if (run_remote && wait) { |
851 | for_each_cpu(cpu, cfd->cpumask) { |
852 | call_single_data_t *csd; |
853 | |
854 | csd = per_cpu_ptr(cfd->csd, cpu); |
855 | csd_lock_wait(csd); |
856 | } |
857 | } |
858 | } |
859 | |
860 | /** |
861 | * smp_call_function_many(): Run a function on a set of CPUs. |
862 | * @mask: The set of cpus to run on (only runs on online subset). |
863 | * @func: The function to run. This must be fast and non-blocking. |
864 | * @info: An arbitrary pointer to pass to the function. |
865 | * @wait: Bitmask that controls the operation. If %SCF_WAIT is set, wait |
866 | * (atomically) until function has completed on other CPUs. If |
867 | * %SCF_RUN_LOCAL is set, the function will also be run locally |
868 | * if the local CPU is set in the @cpumask. |
869 | * |
870 | * If @wait is true, then returns once @func has returned. |
871 | * |
872 | * You must not call this function with disabled interrupts or from a |
873 | * hardware interrupt handler or from a bottom half handler. Preemption |
874 | * must be disabled when calling this function. |
875 | */ |
876 | void smp_call_function_many(const struct cpumask *mask, |
877 | smp_call_func_t func, void *info, bool wait) |
878 | { |
879 | smp_call_function_many_cond(mask, func, info, scf_flags: wait * SCF_WAIT, NULL); |
880 | } |
881 | EXPORT_SYMBOL(smp_call_function_many); |
882 | |
883 | /** |
884 | * smp_call_function(): Run a function on all other CPUs. |
885 | * @func: The function to run. This must be fast and non-blocking. |
886 | * @info: An arbitrary pointer to pass to the function. |
887 | * @wait: If true, wait (atomically) until function has completed |
888 | * on other CPUs. |
889 | * |
890 | * Returns 0. |
891 | * |
892 | * If @wait is true, then returns once @func has returned; otherwise |
893 | * it returns just before the target cpu calls @func. |
894 | * |
895 | * You must not call this function with disabled interrupts or from a |
896 | * hardware interrupt handler or from a bottom half handler. |
897 | */ |
898 | void smp_call_function(smp_call_func_t func, void *info, int wait) |
899 | { |
900 | preempt_disable(); |
901 | smp_call_function_many(cpu_online_mask, func, info, wait); |
902 | preempt_enable(); |
903 | } |
904 | EXPORT_SYMBOL(smp_call_function); |
905 | |
906 | /* Setup configured maximum number of CPUs to activate */ |
907 | unsigned int setup_max_cpus = NR_CPUS; |
908 | EXPORT_SYMBOL(setup_max_cpus); |
909 | |
910 | |
911 | /* |
912 | * Setup routine for controlling SMP activation |
913 | * |
914 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP |
915 | * activation entirely (the MPS table probe still happens, though). |
916 | * |
917 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer |
918 | * greater than 0, limits the maximum number of CPUs activated in |
919 | * SMP mode to <NUM>. |
920 | */ |
921 | |
922 | void __weak __init arch_disable_smp_support(void) { } |
923 | |
924 | static int __init nosmp(char *str) |
925 | { |
926 | setup_max_cpus = 0; |
927 | arch_disable_smp_support(); |
928 | |
929 | return 0; |
930 | } |
931 | |
932 | early_param("nosmp" , nosmp); |
933 | |
934 | /* this is hard limit */ |
935 | static int __init nrcpus(char *str) |
936 | { |
937 | int nr_cpus; |
938 | |
939 | if (get_option(str: &str, pint: &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids) |
940 | set_nr_cpu_ids(nr_cpus); |
941 | |
942 | return 0; |
943 | } |
944 | |
945 | early_param("nr_cpus" , nrcpus); |
946 | |
947 | static int __init maxcpus(char *str) |
948 | { |
949 | get_option(str: &str, pint: &setup_max_cpus); |
950 | if (setup_max_cpus == 0) |
951 | arch_disable_smp_support(); |
952 | |
953 | return 0; |
954 | } |
955 | |
956 | early_param("maxcpus" , maxcpus); |
957 | |
958 | #if (NR_CPUS > 1) && !defined(CONFIG_FORCE_NR_CPUS) |
959 | /* Setup number of possible processor ids */ |
960 | unsigned int nr_cpu_ids __read_mostly = NR_CPUS; |
961 | EXPORT_SYMBOL(nr_cpu_ids); |
962 | #endif |
963 | |
964 | /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ |
965 | void __init setup_nr_cpu_ids(void) |
966 | { |
967 | set_nr_cpu_ids(find_last_bit(cpumask_bits(cpu_possible_mask), NR_CPUS) + 1); |
968 | } |
969 | |
970 | /* Called by boot processor to activate the rest. */ |
971 | void __init smp_init(void) |
972 | { |
973 | int num_nodes, num_cpus; |
974 | |
975 | idle_threads_init(); |
976 | cpuhp_threads_init(); |
977 | |
978 | pr_info("Bringing up secondary CPUs ...\n" ); |
979 | |
980 | bringup_nonboot_cpus(setup_max_cpus); |
981 | |
982 | num_nodes = num_online_nodes(); |
983 | num_cpus = num_online_cpus(); |
984 | pr_info("Brought up %d node%s, %d CPU%s\n" , |
985 | num_nodes, (num_nodes > 1 ? "s" : "" ), |
986 | num_cpus, (num_cpus > 1 ? "s" : "" )); |
987 | |
988 | /* Any cleanup work */ |
989 | smp_cpus_done(max_cpus: setup_max_cpus); |
990 | } |
991 | |
992 | /* |
993 | * on_each_cpu_cond(): Call a function on each processor for which |
994 | * the supplied function cond_func returns true, optionally waiting |
995 | * for all the required CPUs to finish. This may include the local |
996 | * processor. |
997 | * @cond_func: A callback function that is passed a cpu id and |
998 | * the info parameter. The function is called |
999 | * with preemption disabled. The function should |
1000 | * return a blooean value indicating whether to IPI |
1001 | * the specified CPU. |
1002 | * @func: The function to run on all applicable CPUs. |
1003 | * This must be fast and non-blocking. |
1004 | * @info: An arbitrary pointer to pass to both functions. |
1005 | * @wait: If true, wait (atomically) until function has |
1006 | * completed on other CPUs. |
1007 | * |
1008 | * Preemption is disabled to protect against CPUs going offline but not online. |
1009 | * CPUs going online during the call will not be seen or sent an IPI. |
1010 | * |
1011 | * You must not call this function with disabled interrupts or |
1012 | * from a hardware interrupt handler or from a bottom half handler. |
1013 | */ |
1014 | void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func, |
1015 | void *info, bool wait, const struct cpumask *mask) |
1016 | { |
1017 | unsigned int scf_flags = SCF_RUN_LOCAL; |
1018 | |
1019 | if (wait) |
1020 | scf_flags |= SCF_WAIT; |
1021 | |
1022 | preempt_disable(); |
1023 | smp_call_function_many_cond(mask, func, info, scf_flags, cond_func); |
1024 | preempt_enable(); |
1025 | } |
1026 | EXPORT_SYMBOL(on_each_cpu_cond_mask); |
1027 | |
1028 | static void do_nothing(void *unused) |
1029 | { |
1030 | } |
1031 | |
1032 | /** |
1033 | * kick_all_cpus_sync - Force all cpus out of idle |
1034 | * |
1035 | * Used to synchronize the update of pm_idle function pointer. It's |
1036 | * called after the pointer is updated and returns after the dummy |
1037 | * callback function has been executed on all cpus. The execution of |
1038 | * the function can only happen on the remote cpus after they have |
1039 | * left the idle function which had been called via pm_idle function |
1040 | * pointer. So it's guaranteed that nothing uses the previous pointer |
1041 | * anymore. |
1042 | */ |
1043 | void kick_all_cpus_sync(void) |
1044 | { |
1045 | /* Make sure the change is visible before we kick the cpus */ |
1046 | smp_mb(); |
1047 | smp_call_function(do_nothing, NULL, 1); |
1048 | } |
1049 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync); |
1050 | |
1051 | /** |
1052 | * wake_up_all_idle_cpus - break all cpus out of idle |
1053 | * wake_up_all_idle_cpus try to break all cpus which is in idle state even |
1054 | * including idle polling cpus, for non-idle cpus, we will do nothing |
1055 | * for them. |
1056 | */ |
1057 | void wake_up_all_idle_cpus(void) |
1058 | { |
1059 | int cpu; |
1060 | |
1061 | for_each_possible_cpu(cpu) { |
1062 | preempt_disable(); |
1063 | if (cpu != smp_processor_id() && cpu_online(cpu)) |
1064 | wake_up_if_idle(cpu); |
1065 | preempt_enable(); |
1066 | } |
1067 | } |
1068 | EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus); |
1069 | |
1070 | /** |
1071 | * struct smp_call_on_cpu_struct - Call a function on a specific CPU |
1072 | * @work: &work_struct |
1073 | * @done: &completion to signal |
1074 | * @func: function to call |
1075 | * @data: function's data argument |
1076 | * @ret: return value from @func |
1077 | * @cpu: target CPU (%-1 for any CPU) |
1078 | * |
1079 | * Used to call a function on a specific cpu and wait for it to return. |
1080 | * Optionally make sure the call is done on a specified physical cpu via vcpu |
1081 | * pinning in order to support virtualized environments. |
1082 | */ |
1083 | struct smp_call_on_cpu_struct { |
1084 | struct work_struct work; |
1085 | struct completion done; |
1086 | int (*func)(void *); |
1087 | void *data; |
1088 | int ret; |
1089 | int cpu; |
1090 | }; |
1091 | |
1092 | static void smp_call_on_cpu_callback(struct work_struct *work) |
1093 | { |
1094 | struct smp_call_on_cpu_struct *sscs; |
1095 | |
1096 | sscs = container_of(work, struct smp_call_on_cpu_struct, work); |
1097 | if (sscs->cpu >= 0) |
1098 | hypervisor_pin_vcpu(cpu: sscs->cpu); |
1099 | sscs->ret = sscs->func(sscs->data); |
1100 | if (sscs->cpu >= 0) |
1101 | hypervisor_pin_vcpu(cpu: -1); |
1102 | |
1103 | complete(&sscs->done); |
1104 | } |
1105 | |
1106 | int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys) |
1107 | { |
1108 | struct smp_call_on_cpu_struct sscs = { |
1109 | .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done), |
1110 | .func = func, |
1111 | .data = par, |
1112 | .cpu = phys ? cpu : -1, |
1113 | }; |
1114 | |
1115 | INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback); |
1116 | |
1117 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
1118 | return -ENXIO; |
1119 | |
1120 | queue_work_on(cpu, wq: system_wq, work: &sscs.work); |
1121 | wait_for_completion(&sscs.done); |
1122 | |
1123 | return sscs.ret; |
1124 | } |
1125 | EXPORT_SYMBOL_GPL(smp_call_on_cpu); |
1126 | |