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1/*
2 * Generic helpers for smp ipi calls
3 *
4 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/irq_work.h>
10#include <linux/rcupdate.h>
11#include <linux/rculist.h>
12#include <linux/kernel.h>
13#include <linux/export.h>
14#include <linux/percpu.h>
15#include <linux/init.h>
16#include <linux/gfp.h>
17#include <linux/smp.h>
18#include <linux/cpu.h>
19#include <linux/sched.h>
20#include <linux/hypervisor.h>
21
22#include "smpboot.h"
23
24enum {
25 CSD_FLAG_LOCK = 0x01,
26 CSD_FLAG_SYNCHRONOUS = 0x02,
27};
28
29struct call_function_data {
30 struct call_single_data __percpu *csd;
31 cpumask_var_t cpumask;
32};
33
34static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data);
35
36static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
37
38static void flush_smp_call_function_queue(bool warn_cpu_offline);
39
40int smpcfd_prepare_cpu(unsigned int cpu)
41{
42 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
43
44 if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
45 cpu_to_node(cpu)))
46 return -ENOMEM;
47 cfd->csd = alloc_percpu(struct call_single_data);
48 if (!cfd->csd) {
49 free_cpumask_var(cfd->cpumask);
50 return -ENOMEM;
51 }
52
53 return 0;
54}
55
56int smpcfd_dead_cpu(unsigned int cpu)
57{
58 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
59
60 free_cpumask_var(cfd->cpumask);
61 free_percpu(cfd->csd);
62 return 0;
63}
64
65int smpcfd_dying_cpu(unsigned int cpu)
66{
67 /*
68 * The IPIs for the smp-call-function callbacks queued by other
69 * CPUs might arrive late, either due to hardware latencies or
70 * because this CPU disabled interrupts (inside stop-machine)
71 * before the IPIs were sent. So flush out any pending callbacks
72 * explicitly (without waiting for the IPIs to arrive), to
73 * ensure that the outgoing CPU doesn't go offline with work
74 * still pending.
75 */
76 flush_smp_call_function_queue(false);
77 return 0;
78}
79
80void __init call_function_init(void)
81{
82 int i;
83
84 for_each_possible_cpu(i)
85 init_llist_head(&per_cpu(call_single_queue, i));
86
87 smpcfd_prepare_cpu(smp_processor_id());
88}
89
90/*
91 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
92 *
93 * For non-synchronous ipi calls the csd can still be in use by the
94 * previous function call. For multi-cpu calls its even more interesting
95 * as we'll have to ensure no other cpu is observing our csd.
96 */
97static __always_inline void csd_lock_wait(struct call_single_data *csd)
98{
99 smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
100}
101
102static __always_inline void csd_lock(struct call_single_data *csd)
103{
104 csd_lock_wait(csd);
105 csd->flags |= CSD_FLAG_LOCK;
106
107 /*
108 * prevent CPU from reordering the above assignment
109 * to ->flags with any subsequent assignments to other
110 * fields of the specified call_single_data structure:
111 */
112 smp_wmb();
113}
114
115static __always_inline void csd_unlock(struct call_single_data *csd)
116{
117 WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
118
119 /*
120 * ensure we're all done before releasing data:
121 */
122 smp_store_release(&csd->flags, 0);
123}
124
125static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
126
127/*
128 * Insert a previously allocated call_single_data element
129 * for execution on the given CPU. data must already have
130 * ->func, ->info, and ->flags set.
131 */
132static int generic_exec_single(int cpu, struct call_single_data *csd,
133 smp_call_func_t func, void *info)
134{
135 if (cpu == smp_processor_id()) {
136 unsigned long flags;
137
138 /*
139 * We can unlock early even for the synchronous on-stack case,
140 * since we're doing this from the same CPU..
141 */
142 csd_unlock(csd);
143 local_irq_save(flags);
144 func(info);
145 local_irq_restore(flags);
146 return 0;
147 }
148
149
150 if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
151 csd_unlock(csd);
152 return -ENXIO;
153 }
154
155 csd->func = func;
156 csd->info = info;
157
158 /*
159 * The list addition should be visible before sending the IPI
160 * handler locks the list to pull the entry off it because of
161 * normal cache coherency rules implied by spinlocks.
162 *
163 * If IPIs can go out of order to the cache coherency protocol
164 * in an architecture, sufficient synchronisation should be added
165 * to arch code to make it appear to obey cache coherency WRT
166 * locking and barrier primitives. Generic code isn't really
167 * equipped to do the right thing...
168 */
169 if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
170 arch_send_call_function_single_ipi(cpu);
171
172 return 0;
173}
174
175/**
176 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
177 *
178 * Invoked by arch to handle an IPI for call function single.
179 * Must be called with interrupts disabled.
180 */
181void generic_smp_call_function_single_interrupt(void)
182{
183 flush_smp_call_function_queue(true);
184}
185
186/**
187 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
188 *
189 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
190 * offline CPU. Skip this check if set to 'false'.
191 *
192 * Flush any pending smp-call-function callbacks queued on this CPU. This is
193 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
194 * to ensure that all pending IPI callbacks are run before it goes completely
195 * offline.
196 *
197 * Loop through the call_single_queue and run all the queued callbacks.
198 * Must be called with interrupts disabled.
199 */
200static void flush_smp_call_function_queue(bool warn_cpu_offline)
201{
202 struct llist_head *head;
203 struct llist_node *entry;
204 struct call_single_data *csd, *csd_next;
205 static bool warned;
206
207 WARN_ON(!irqs_disabled());
208
209 head = this_cpu_ptr(&call_single_queue);
210 entry = llist_del_all(head);
211 entry = llist_reverse_order(entry);
212
213 /* There shouldn't be any pending callbacks on an offline CPU. */
214 if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
215 !warned && !llist_empty(head))) {
216 warned = true;
217 WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
218
219 /*
220 * We don't have to use the _safe() variant here
221 * because we are not invoking the IPI handlers yet.
222 */
223 llist_for_each_entry(csd, entry, llist)
224 pr_warn("IPI callback %pS sent to offline CPU\n",
225 csd->func);
226 }
227
228 llist_for_each_entry_safe(csd, csd_next, entry, llist) {
229 smp_call_func_t func = csd->func;
230 void *info = csd->info;
231
232 /* Do we wait until *after* callback? */
233 if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
234 func(info);
235 csd_unlock(csd);
236 } else {
237 csd_unlock(csd);
238 func(info);
239 }
240 }
241
242 /*
243 * Handle irq works queued remotely by irq_work_queue_on().
244 * Smp functions above are typically synchronous so they
245 * better run first since some other CPUs may be busy waiting
246 * for them.
247 */
248 irq_work_run();
249}
250
251/*
252 * smp_call_function_single - Run a function on a specific CPU
253 * @func: The function to run. This must be fast and non-blocking.
254 * @info: An arbitrary pointer to pass to the function.
255 * @wait: If true, wait until function has completed on other CPUs.
256 *
257 * Returns 0 on success, else a negative status code.
258 */
259int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
260 int wait)
261{
262 struct call_single_data *csd;
263 struct call_single_data csd_stack = { .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS };
264 int this_cpu;
265 int err;
266
267 /*
268 * prevent preemption and reschedule on another processor,
269 * as well as CPU removal
270 */
271 this_cpu = get_cpu();
272
273 /*
274 * Can deadlock when called with interrupts disabled.
275 * We allow cpu's that are not yet online though, as no one else can
276 * send smp call function interrupt to this cpu and as such deadlocks
277 * can't happen.
278 */
279 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
280 && !oops_in_progress);
281
282 csd = &csd_stack;
283 if (!wait) {
284 csd = this_cpu_ptr(&csd_data);
285 csd_lock(csd);
286 }
287
288 err = generic_exec_single(cpu, csd, func, info);
289
290 if (wait)
291 csd_lock_wait(csd);
292
293 put_cpu();
294
295 return err;
296}
297EXPORT_SYMBOL(smp_call_function_single);
298
299/**
300 * smp_call_function_single_async(): Run an asynchronous function on a
301 * specific CPU.
302 * @cpu: The CPU to run on.
303 * @csd: Pre-allocated and setup data structure
304 *
305 * Like smp_call_function_single(), but the call is asynchonous and
306 * can thus be done from contexts with disabled interrupts.
307 *
308 * The caller passes his own pre-allocated data structure
309 * (ie: embedded in an object) and is responsible for synchronizing it
310 * such that the IPIs performed on the @csd are strictly serialized.
311 *
312 * NOTE: Be careful, there is unfortunately no current debugging facility to
313 * validate the correctness of this serialization.
314 */
315int smp_call_function_single_async(int cpu, struct call_single_data *csd)
316{
317 int err = 0;
318
319 preempt_disable();
320
321 /* We could deadlock if we have to wait here with interrupts disabled! */
322 if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
323 csd_lock_wait(csd);
324
325 csd->flags = CSD_FLAG_LOCK;
326 smp_wmb();
327
328 err = generic_exec_single(cpu, csd, csd->func, csd->info);
329 preempt_enable();
330
331 return err;
332}
333EXPORT_SYMBOL_GPL(smp_call_function_single_async);
334
335/*
336 * smp_call_function_any - Run a function on any of the given cpus
337 * @mask: The mask of cpus it can run on.
338 * @func: The function to run. This must be fast and non-blocking.
339 * @info: An arbitrary pointer to pass to the function.
340 * @wait: If true, wait until function has completed.
341 *
342 * Returns 0 on success, else a negative status code (if no cpus were online).
343 *
344 * Selection preference:
345 * 1) current cpu if in @mask
346 * 2) any cpu of current node if in @mask
347 * 3) any other online cpu in @mask
348 */
349int smp_call_function_any(const struct cpumask *mask,
350 smp_call_func_t func, void *info, int wait)
351{
352 unsigned int cpu;
353 const struct cpumask *nodemask;
354 int ret;
355
356 /* Try for same CPU (cheapest) */
357 cpu = get_cpu();
358 if (cpumask_test_cpu(cpu, mask))
359 goto call;
360
361 /* Try for same node. */
362 nodemask = cpumask_of_node(cpu_to_node(cpu));
363 for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
364 cpu = cpumask_next_and(cpu, nodemask, mask)) {
365 if (cpu_online(cpu))
366 goto call;
367 }
368
369 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
370 cpu = cpumask_any_and(mask, cpu_online_mask);
371call:
372 ret = smp_call_function_single(cpu, func, info, wait);
373 put_cpu();
374 return ret;
375}
376EXPORT_SYMBOL_GPL(smp_call_function_any);
377
378/**
379 * smp_call_function_many(): Run a function on a set of other CPUs.
380 * @mask: The set of cpus to run on (only runs on online subset).
381 * @func: The function to run. This must be fast and non-blocking.
382 * @info: An arbitrary pointer to pass to the function.
383 * @wait: If true, wait (atomically) until function has completed
384 * on other CPUs.
385 *
386 * If @wait is true, then returns once @func has returned.
387 *
388 * You must not call this function with disabled interrupts or from a
389 * hardware interrupt handler or from a bottom half handler. Preemption
390 * must be disabled when calling this function.
391 */
392void smp_call_function_many(const struct cpumask *mask,
393 smp_call_func_t func, void *info, bool wait)
394{
395 struct call_function_data *cfd;
396 int cpu, next_cpu, this_cpu = smp_processor_id();
397
398 /*
399 * Can deadlock when called with interrupts disabled.
400 * We allow cpu's that are not yet online though, as no one else can
401 * send smp call function interrupt to this cpu and as such deadlocks
402 * can't happen.
403 */
404 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
405 && !oops_in_progress && !early_boot_irqs_disabled);
406
407 /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
408 cpu = cpumask_first_and(mask, cpu_online_mask);
409 if (cpu == this_cpu)
410 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
411
412 /* No online cpus? We're done. */
413 if (cpu >= nr_cpu_ids)
414 return;
415
416 /* Do we have another CPU which isn't us? */
417 next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
418 if (next_cpu == this_cpu)
419 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
420
421 /* Fastpath: do that cpu by itself. */
422 if (next_cpu >= nr_cpu_ids) {
423 smp_call_function_single(cpu, func, info, wait);
424 return;
425 }
426
427 cfd = this_cpu_ptr(&cfd_data);
428
429 cpumask_and(cfd->cpumask, mask, cpu_online_mask);
430 cpumask_clear_cpu(this_cpu, cfd->cpumask);
431
432 /* Some callers race with other cpus changing the passed mask */
433 if (unlikely(!cpumask_weight(cfd->cpumask)))
434 return;
435
436 for_each_cpu(cpu, cfd->cpumask) {
437 struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu);
438
439 csd_lock(csd);
440 if (wait)
441 csd->flags |= CSD_FLAG_SYNCHRONOUS;
442 csd->func = func;
443 csd->info = info;
444 llist_add(&csd->llist, &per_cpu(call_single_queue, cpu));
445 }
446
447 /* Send a message to all CPUs in the map */
448 arch_send_call_function_ipi_mask(cfd->cpumask);
449
450 if (wait) {
451 for_each_cpu(cpu, cfd->cpumask) {
452 struct call_single_data *csd;
453
454 csd = per_cpu_ptr(cfd->csd, cpu);
455 csd_lock_wait(csd);
456 }
457 }
458}
459EXPORT_SYMBOL(smp_call_function_many);
460
461/**
462 * smp_call_function(): Run a function on all other CPUs.
463 * @func: The function to run. This must be fast and non-blocking.
464 * @info: An arbitrary pointer to pass to the function.
465 * @wait: If true, wait (atomically) until function has completed
466 * on other CPUs.
467 *
468 * Returns 0.
469 *
470 * If @wait is true, then returns once @func has returned; otherwise
471 * it returns just before the target cpu calls @func.
472 *
473 * You must not call this function with disabled interrupts or from a
474 * hardware interrupt handler or from a bottom half handler.
475 */
476int smp_call_function(smp_call_func_t func, void *info, int wait)
477{
478 preempt_disable();
479 smp_call_function_many(cpu_online_mask, func, info, wait);
480 preempt_enable();
481
482 return 0;
483}
484EXPORT_SYMBOL(smp_call_function);
485
486/* Setup configured maximum number of CPUs to activate */
487unsigned int setup_max_cpus = NR_CPUS;
488EXPORT_SYMBOL(setup_max_cpus);
489
490
491/*
492 * Setup routine for controlling SMP activation
493 *
494 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
495 * activation entirely (the MPS table probe still happens, though).
496 *
497 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
498 * greater than 0, limits the maximum number of CPUs activated in
499 * SMP mode to <NUM>.
500 */
501
502void __weak arch_disable_smp_support(void) { }
503
504static int __init nosmp(char *str)
505{
506 setup_max_cpus = 0;
507 arch_disable_smp_support();
508
509 return 0;
510}
511
512early_param("nosmp", nosmp);
513
514/* this is hard limit */
515static int __init nrcpus(char *str)
516{
517 int nr_cpus;
518
519 get_option(&str, &nr_cpus);
520 if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
521 nr_cpu_ids = nr_cpus;
522
523 return 0;
524}
525
526early_param("nr_cpus", nrcpus);
527
528static int __init maxcpus(char *str)
529{
530 get_option(&str, &setup_max_cpus);
531 if (setup_max_cpus == 0)
532 arch_disable_smp_support();
533
534 return 0;
535}
536
537early_param("maxcpus", maxcpus);
538
539/* Setup number of possible processor ids */
540int nr_cpu_ids __read_mostly = NR_CPUS;
541EXPORT_SYMBOL(nr_cpu_ids);
542
543/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
544void __init setup_nr_cpu_ids(void)
545{
546 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
547}
548
549/* Called by boot processor to activate the rest. */
550void __init smp_init(void)
551{
552 int num_nodes, num_cpus;
553 unsigned int cpu;
554
555 idle_threads_init();
556 cpuhp_threads_init();
557
558 pr_info("Bringing up secondary CPUs ...\n");
559
560 /* FIXME: This should be done in userspace --RR */
561 for_each_present_cpu(cpu) {
562 if (num_online_cpus() >= setup_max_cpus)
563 break;
564 if (!cpu_online(cpu))
565 cpu_up(cpu);
566 }
567
568 num_nodes = num_online_nodes();
569 num_cpus = num_online_cpus();
570 pr_info("Brought up %d node%s, %d CPU%s\n",
571 num_nodes, (num_nodes > 1 ? "s" : ""),
572 num_cpus, (num_cpus > 1 ? "s" : ""));
573
574 /* Any cleanup work */
575 smp_cpus_done(setup_max_cpus);
576}
577
578/*
579 * Call a function on all processors. May be used during early boot while
580 * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
581 * of local_irq_disable/enable().
582 */
583int on_each_cpu(void (*func) (void *info), void *info, int wait)
584{
585 unsigned long flags;
586 int ret = 0;
587
588 preempt_disable();
589 ret = smp_call_function(func, info, wait);
590 local_irq_save(flags);
591 func(info);
592 local_irq_restore(flags);
593 preempt_enable();
594 return ret;
595}
596EXPORT_SYMBOL(on_each_cpu);
597
598/**
599 * on_each_cpu_mask(): Run a function on processors specified by
600 * cpumask, which may include the local processor.
601 * @mask: The set of cpus to run on (only runs on online subset).
602 * @func: The function to run. This must be fast and non-blocking.
603 * @info: An arbitrary pointer to pass to the function.
604 * @wait: If true, wait (atomically) until function has completed
605 * on other CPUs.
606 *
607 * If @wait is true, then returns once @func has returned.
608 *
609 * You must not call this function with disabled interrupts or from a
610 * hardware interrupt handler or from a bottom half handler. The
611 * exception is that it may be used during early boot while
612 * early_boot_irqs_disabled is set.
613 */
614void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
615 void *info, bool wait)
616{
617 int cpu = get_cpu();
618
619 smp_call_function_many(mask, func, info, wait);
620 if (cpumask_test_cpu(cpu, mask)) {
621 unsigned long flags;
622 local_irq_save(flags);
623 func(info);
624 local_irq_restore(flags);
625 }
626 put_cpu();
627}
628EXPORT_SYMBOL(on_each_cpu_mask);
629
630/*
631 * on_each_cpu_cond(): Call a function on each processor for which
632 * the supplied function cond_func returns true, optionally waiting
633 * for all the required CPUs to finish. This may include the local
634 * processor.
635 * @cond_func: A callback function that is passed a cpu id and
636 * the the info parameter. The function is called
637 * with preemption disabled. The function should
638 * return a blooean value indicating whether to IPI
639 * the specified CPU.
640 * @func: The function to run on all applicable CPUs.
641 * This must be fast and non-blocking.
642 * @info: An arbitrary pointer to pass to both functions.
643 * @wait: If true, wait (atomically) until function has
644 * completed on other CPUs.
645 * @gfp_flags: GFP flags to use when allocating the cpumask
646 * used internally by the function.
647 *
648 * The function might sleep if the GFP flags indicates a non
649 * atomic allocation is allowed.
650 *
651 * Preemption is disabled to protect against CPUs going offline but not online.
652 * CPUs going online during the call will not be seen or sent an IPI.
653 *
654 * You must not call this function with disabled interrupts or
655 * from a hardware interrupt handler or from a bottom half handler.
656 */
657void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
658 smp_call_func_t func, void *info, bool wait,
659 gfp_t gfp_flags)
660{
661 cpumask_var_t cpus;
662 int cpu, ret;
663
664 might_sleep_if(gfpflags_allow_blocking(gfp_flags));
665
666 if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
667 preempt_disable();
668 for_each_online_cpu(cpu)
669 if (cond_func(cpu, info))
670 cpumask_set_cpu(cpu, cpus);
671 on_each_cpu_mask(cpus, func, info, wait);
672 preempt_enable();
673 free_cpumask_var(cpus);
674 } else {
675 /*
676 * No free cpumask, bother. No matter, we'll
677 * just have to IPI them one by one.
678 */
679 preempt_disable();
680 for_each_online_cpu(cpu)
681 if (cond_func(cpu, info)) {
682 ret = smp_call_function_single(cpu, func,
683 info, wait);
684 WARN_ON_ONCE(ret);
685 }
686 preempt_enable();
687 }
688}
689EXPORT_SYMBOL(on_each_cpu_cond);
690
691static void do_nothing(void *unused)
692{
693}
694
695/**
696 * kick_all_cpus_sync - Force all cpus out of idle
697 *
698 * Used to synchronize the update of pm_idle function pointer. It's
699 * called after the pointer is updated and returns after the dummy
700 * callback function has been executed on all cpus. The execution of
701 * the function can only happen on the remote cpus after they have
702 * left the idle function which had been called via pm_idle function
703 * pointer. So it's guaranteed that nothing uses the previous pointer
704 * anymore.
705 */
706void kick_all_cpus_sync(void)
707{
708 /* Make sure the change is visible before we kick the cpus */
709 smp_mb();
710 smp_call_function(do_nothing, NULL, 1);
711}
712EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
713
714/**
715 * wake_up_all_idle_cpus - break all cpus out of idle
716 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
717 * including idle polling cpus, for non-idle cpus, we will do nothing
718 * for them.
719 */
720void wake_up_all_idle_cpus(void)
721{
722 int cpu;
723
724 preempt_disable();
725 for_each_online_cpu(cpu) {
726 if (cpu == smp_processor_id())
727 continue;
728
729 wake_up_if_idle(cpu);
730 }
731 preempt_enable();
732}
733EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
734
735/**
736 * smp_call_on_cpu - Call a function on a specific cpu
737 *
738 * Used to call a function on a specific cpu and wait for it to return.
739 * Optionally make sure the call is done on a specified physical cpu via vcpu
740 * pinning in order to support virtualized environments.
741 */
742struct smp_call_on_cpu_struct {
743 struct work_struct work;
744 struct completion done;
745 int (*func)(void *);
746 void *data;
747 int ret;
748 int cpu;
749};
750
751static void smp_call_on_cpu_callback(struct work_struct *work)
752{
753 struct smp_call_on_cpu_struct *sscs;
754
755 sscs = container_of(work, struct smp_call_on_cpu_struct, work);
756 if (sscs->cpu >= 0)
757 hypervisor_pin_vcpu(sscs->cpu);
758 sscs->ret = sscs->func(sscs->data);
759 if (sscs->cpu >= 0)
760 hypervisor_pin_vcpu(-1);
761
762 complete(&sscs->done);
763}
764
765int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
766{
767 struct smp_call_on_cpu_struct sscs = {
768 .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
769 .func = func,
770 .data = par,
771 .cpu = phys ? cpu : -1,
772 };
773
774 INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
775
776 if (cpu >= nr_cpu_ids || !cpu_online(cpu))
777 return -ENXIO;
778
779 queue_work_on(cpu, system_wq, &sscs.work);
780 wait_for_completion(&sscs.done);
781
782 return sscs.ret;
783}
784EXPORT_SYMBOL_GPL(smp_call_on_cpu);
1/*
2 * Generic helpers for smp ipi calls
3 *
4 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
5 */
6#include <linux/irq_work.h>
7#include <linux/rcupdate.h>
8#include <linux/rculist.h>
9#include <linux/kernel.h>
10#include <linux/export.h>
11#include <linux/percpu.h>
12#include <linux/init.h>
13#include <linux/gfp.h>
14#include <linux/smp.h>
15#include <linux/cpu.h>
16#include <linux/sched.h>
17
18#include "smpboot.h"
19
20enum {
21 CSD_FLAG_LOCK = 0x01,
22 CSD_FLAG_SYNCHRONOUS = 0x02,
23};
24
25struct call_function_data {
26 struct call_single_data __percpu *csd;
27 cpumask_var_t cpumask;
28};
29
30static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data);
31
32static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
33
34static void flush_smp_call_function_queue(bool warn_cpu_offline);
35
36static int
37hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
38{
39 long cpu = (long)hcpu;
40 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
41
42 switch (action) {
43 case CPU_UP_PREPARE:
44 case CPU_UP_PREPARE_FROZEN:
45 if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
46 cpu_to_node(cpu)))
47 return notifier_from_errno(-ENOMEM);
48 cfd->csd = alloc_percpu(struct call_single_data);
49 if (!cfd->csd) {
50 free_cpumask_var(cfd->cpumask);
51 return notifier_from_errno(-ENOMEM);
52 }
53 break;
54
55#ifdef CONFIG_HOTPLUG_CPU
56 case CPU_UP_CANCELED:
57 case CPU_UP_CANCELED_FROZEN:
58 /* Fall-through to the CPU_DEAD[_FROZEN] case. */
59
60 case CPU_DEAD:
61 case CPU_DEAD_FROZEN:
62 free_cpumask_var(cfd->cpumask);
63 free_percpu(cfd->csd);
64 break;
65
66 case CPU_DYING:
67 case CPU_DYING_FROZEN:
68 /*
69 * The IPIs for the smp-call-function callbacks queued by other
70 * CPUs might arrive late, either due to hardware latencies or
71 * because this CPU disabled interrupts (inside stop-machine)
72 * before the IPIs were sent. So flush out any pending callbacks
73 * explicitly (without waiting for the IPIs to arrive), to
74 * ensure that the outgoing CPU doesn't go offline with work
75 * still pending.
76 */
77 flush_smp_call_function_queue(false);
78 break;
79#endif
80 };
81
82 return NOTIFY_OK;
83}
84
85static struct notifier_block hotplug_cfd_notifier = {
86 .notifier_call = hotplug_cfd,
87};
88
89void __init call_function_init(void)
90{
91 void *cpu = (void *)(long)smp_processor_id();
92 int i;
93
94 for_each_possible_cpu(i)
95 init_llist_head(&per_cpu(call_single_queue, i));
96
97 hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
98 register_cpu_notifier(&hotplug_cfd_notifier);
99}
100
101/*
102 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
103 *
104 * For non-synchronous ipi calls the csd can still be in use by the
105 * previous function call. For multi-cpu calls its even more interesting
106 * as we'll have to ensure no other cpu is observing our csd.
107 */
108static __always_inline void csd_lock_wait(struct call_single_data *csd)
109{
110 smp_cond_acquire(!(csd->flags & CSD_FLAG_LOCK));
111}
112
113static __always_inline void csd_lock(struct call_single_data *csd)
114{
115 csd_lock_wait(csd);
116 csd->flags |= CSD_FLAG_LOCK;
117
118 /*
119 * prevent CPU from reordering the above assignment
120 * to ->flags with any subsequent assignments to other
121 * fields of the specified call_single_data structure:
122 */
123 smp_wmb();
124}
125
126static __always_inline void csd_unlock(struct call_single_data *csd)
127{
128 WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
129
130 /*
131 * ensure we're all done before releasing data:
132 */
133 smp_store_release(&csd->flags, 0);
134}
135
136static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
137
138/*
139 * Insert a previously allocated call_single_data element
140 * for execution on the given CPU. data must already have
141 * ->func, ->info, and ->flags set.
142 */
143static int generic_exec_single(int cpu, struct call_single_data *csd,
144 smp_call_func_t func, void *info)
145{
146 if (cpu == smp_processor_id()) {
147 unsigned long flags;
148
149 /*
150 * We can unlock early even for the synchronous on-stack case,
151 * since we're doing this from the same CPU..
152 */
153 csd_unlock(csd);
154 local_irq_save(flags);
155 func(info);
156 local_irq_restore(flags);
157 return 0;
158 }
159
160
161 if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
162 csd_unlock(csd);
163 return -ENXIO;
164 }
165
166 csd->func = func;
167 csd->info = info;
168
169 /*
170 * The list addition should be visible before sending the IPI
171 * handler locks the list to pull the entry off it because of
172 * normal cache coherency rules implied by spinlocks.
173 *
174 * If IPIs can go out of order to the cache coherency protocol
175 * in an architecture, sufficient synchronisation should be added
176 * to arch code to make it appear to obey cache coherency WRT
177 * locking and barrier primitives. Generic code isn't really
178 * equipped to do the right thing...
179 */
180 if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
181 arch_send_call_function_single_ipi(cpu);
182
183 return 0;
184}
185
186/**
187 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
188 *
189 * Invoked by arch to handle an IPI for call function single.
190 * Must be called with interrupts disabled.
191 */
192void generic_smp_call_function_single_interrupt(void)
193{
194 flush_smp_call_function_queue(true);
195}
196
197/**
198 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
199 *
200 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
201 * offline CPU. Skip this check if set to 'false'.
202 *
203 * Flush any pending smp-call-function callbacks queued on this CPU. This is
204 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
205 * to ensure that all pending IPI callbacks are run before it goes completely
206 * offline.
207 *
208 * Loop through the call_single_queue and run all the queued callbacks.
209 * Must be called with interrupts disabled.
210 */
211static void flush_smp_call_function_queue(bool warn_cpu_offline)
212{
213 struct llist_head *head;
214 struct llist_node *entry;
215 struct call_single_data *csd, *csd_next;
216 static bool warned;
217
218 WARN_ON(!irqs_disabled());
219
220 head = this_cpu_ptr(&call_single_queue);
221 entry = llist_del_all(head);
222 entry = llist_reverse_order(entry);
223
224 /* There shouldn't be any pending callbacks on an offline CPU. */
225 if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
226 !warned && !llist_empty(head))) {
227 warned = true;
228 WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
229
230 /*
231 * We don't have to use the _safe() variant here
232 * because we are not invoking the IPI handlers yet.
233 */
234 llist_for_each_entry(csd, entry, llist)
235 pr_warn("IPI callback %pS sent to offline CPU\n",
236 csd->func);
237 }
238
239 llist_for_each_entry_safe(csd, csd_next, entry, llist) {
240 smp_call_func_t func = csd->func;
241 void *info = csd->info;
242
243 /* Do we wait until *after* callback? */
244 if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
245 func(info);
246 csd_unlock(csd);
247 } else {
248 csd_unlock(csd);
249 func(info);
250 }
251 }
252
253 /*
254 * Handle irq works queued remotely by irq_work_queue_on().
255 * Smp functions above are typically synchronous so they
256 * better run first since some other CPUs may be busy waiting
257 * for them.
258 */
259 irq_work_run();
260}
261
262/*
263 * smp_call_function_single - Run a function on a specific CPU
264 * @func: The function to run. This must be fast and non-blocking.
265 * @info: An arbitrary pointer to pass to the function.
266 * @wait: If true, wait until function has completed on other CPUs.
267 *
268 * Returns 0 on success, else a negative status code.
269 */
270int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
271 int wait)
272{
273 struct call_single_data *csd;
274 struct call_single_data csd_stack = { .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS };
275 int this_cpu;
276 int err;
277
278 /*
279 * prevent preemption and reschedule on another processor,
280 * as well as CPU removal
281 */
282 this_cpu = get_cpu();
283
284 /*
285 * Can deadlock when called with interrupts disabled.
286 * We allow cpu's that are not yet online though, as no one else can
287 * send smp call function interrupt to this cpu and as such deadlocks
288 * can't happen.
289 */
290 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
291 && !oops_in_progress);
292
293 csd = &csd_stack;
294 if (!wait) {
295 csd = this_cpu_ptr(&csd_data);
296 csd_lock(csd);
297 }
298
299 err = generic_exec_single(cpu, csd, func, info);
300
301 if (wait)
302 csd_lock_wait(csd);
303
304 put_cpu();
305
306 return err;
307}
308EXPORT_SYMBOL(smp_call_function_single);
309
310/**
311 * smp_call_function_single_async(): Run an asynchronous function on a
312 * specific CPU.
313 * @cpu: The CPU to run on.
314 * @csd: Pre-allocated and setup data structure
315 *
316 * Like smp_call_function_single(), but the call is asynchonous and
317 * can thus be done from contexts with disabled interrupts.
318 *
319 * The caller passes his own pre-allocated data structure
320 * (ie: embedded in an object) and is responsible for synchronizing it
321 * such that the IPIs performed on the @csd are strictly serialized.
322 *
323 * NOTE: Be careful, there is unfortunately no current debugging facility to
324 * validate the correctness of this serialization.
325 */
326int smp_call_function_single_async(int cpu, struct call_single_data *csd)
327{
328 int err = 0;
329
330 preempt_disable();
331
332 /* We could deadlock if we have to wait here with interrupts disabled! */
333 if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
334 csd_lock_wait(csd);
335
336 csd->flags = CSD_FLAG_LOCK;
337 smp_wmb();
338
339 err = generic_exec_single(cpu, csd, csd->func, csd->info);
340 preempt_enable();
341
342 return err;
343}
344EXPORT_SYMBOL_GPL(smp_call_function_single_async);
345
346/*
347 * smp_call_function_any - Run a function on any of the given cpus
348 * @mask: The mask of cpus it can run on.
349 * @func: The function to run. This must be fast and non-blocking.
350 * @info: An arbitrary pointer to pass to the function.
351 * @wait: If true, wait until function has completed.
352 *
353 * Returns 0 on success, else a negative status code (if no cpus were online).
354 *
355 * Selection preference:
356 * 1) current cpu if in @mask
357 * 2) any cpu of current node if in @mask
358 * 3) any other online cpu in @mask
359 */
360int smp_call_function_any(const struct cpumask *mask,
361 smp_call_func_t func, void *info, int wait)
362{
363 unsigned int cpu;
364 const struct cpumask *nodemask;
365 int ret;
366
367 /* Try for same CPU (cheapest) */
368 cpu = get_cpu();
369 if (cpumask_test_cpu(cpu, mask))
370 goto call;
371
372 /* Try for same node. */
373 nodemask = cpumask_of_node(cpu_to_node(cpu));
374 for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
375 cpu = cpumask_next_and(cpu, nodemask, mask)) {
376 if (cpu_online(cpu))
377 goto call;
378 }
379
380 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
381 cpu = cpumask_any_and(mask, cpu_online_mask);
382call:
383 ret = smp_call_function_single(cpu, func, info, wait);
384 put_cpu();
385 return ret;
386}
387EXPORT_SYMBOL_GPL(smp_call_function_any);
388
389/**
390 * smp_call_function_many(): Run a function on a set of other CPUs.
391 * @mask: The set of cpus to run on (only runs on online subset).
392 * @func: The function to run. This must be fast and non-blocking.
393 * @info: An arbitrary pointer to pass to the function.
394 * @wait: If true, wait (atomically) until function has completed
395 * on other CPUs.
396 *
397 * If @wait is true, then returns once @func has returned.
398 *
399 * You must not call this function with disabled interrupts or from a
400 * hardware interrupt handler or from a bottom half handler. Preemption
401 * must be disabled when calling this function.
402 */
403void smp_call_function_many(const struct cpumask *mask,
404 smp_call_func_t func, void *info, bool wait)
405{
406 struct call_function_data *cfd;
407 int cpu, next_cpu, this_cpu = smp_processor_id();
408
409 /*
410 * Can deadlock when called with interrupts disabled.
411 * We allow cpu's that are not yet online though, as no one else can
412 * send smp call function interrupt to this cpu and as such deadlocks
413 * can't happen.
414 */
415 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
416 && !oops_in_progress && !early_boot_irqs_disabled);
417
418 /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
419 cpu = cpumask_first_and(mask, cpu_online_mask);
420 if (cpu == this_cpu)
421 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
422
423 /* No online cpus? We're done. */
424 if (cpu >= nr_cpu_ids)
425 return;
426
427 /* Do we have another CPU which isn't us? */
428 next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
429 if (next_cpu == this_cpu)
430 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
431
432 /* Fastpath: do that cpu by itself. */
433 if (next_cpu >= nr_cpu_ids) {
434 smp_call_function_single(cpu, func, info, wait);
435 return;
436 }
437
438 cfd = this_cpu_ptr(&cfd_data);
439
440 cpumask_and(cfd->cpumask, mask, cpu_online_mask);
441 cpumask_clear_cpu(this_cpu, cfd->cpumask);
442
443 /* Some callers race with other cpus changing the passed mask */
444 if (unlikely(!cpumask_weight(cfd->cpumask)))
445 return;
446
447 for_each_cpu(cpu, cfd->cpumask) {
448 struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu);
449
450 csd_lock(csd);
451 if (wait)
452 csd->flags |= CSD_FLAG_SYNCHRONOUS;
453 csd->func = func;
454 csd->info = info;
455 llist_add(&csd->llist, &per_cpu(call_single_queue, cpu));
456 }
457
458 /* Send a message to all CPUs in the map */
459 arch_send_call_function_ipi_mask(cfd->cpumask);
460
461 if (wait) {
462 for_each_cpu(cpu, cfd->cpumask) {
463 struct call_single_data *csd;
464
465 csd = per_cpu_ptr(cfd->csd, cpu);
466 csd_lock_wait(csd);
467 }
468 }
469}
470EXPORT_SYMBOL(smp_call_function_many);
471
472/**
473 * smp_call_function(): Run a function on all other CPUs.
474 * @func: The function to run. This must be fast and non-blocking.
475 * @info: An arbitrary pointer to pass to the function.
476 * @wait: If true, wait (atomically) until function has completed
477 * on other CPUs.
478 *
479 * Returns 0.
480 *
481 * If @wait is true, then returns once @func has returned; otherwise
482 * it returns just before the target cpu calls @func.
483 *
484 * You must not call this function with disabled interrupts or from a
485 * hardware interrupt handler or from a bottom half handler.
486 */
487int smp_call_function(smp_call_func_t func, void *info, int wait)
488{
489 preempt_disable();
490 smp_call_function_many(cpu_online_mask, func, info, wait);
491 preempt_enable();
492
493 return 0;
494}
495EXPORT_SYMBOL(smp_call_function);
496
497/* Setup configured maximum number of CPUs to activate */
498unsigned int setup_max_cpus = NR_CPUS;
499EXPORT_SYMBOL(setup_max_cpus);
500
501
502/*
503 * Setup routine for controlling SMP activation
504 *
505 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
506 * activation entirely (the MPS table probe still happens, though).
507 *
508 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
509 * greater than 0, limits the maximum number of CPUs activated in
510 * SMP mode to <NUM>.
511 */
512
513void __weak arch_disable_smp_support(void) { }
514
515static int __init nosmp(char *str)
516{
517 setup_max_cpus = 0;
518 arch_disable_smp_support();
519
520 return 0;
521}
522
523early_param("nosmp", nosmp);
524
525/* this is hard limit */
526static int __init nrcpus(char *str)
527{
528 int nr_cpus;
529
530 get_option(&str, &nr_cpus);
531 if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
532 nr_cpu_ids = nr_cpus;
533
534 return 0;
535}
536
537early_param("nr_cpus", nrcpus);
538
539static int __init maxcpus(char *str)
540{
541 get_option(&str, &setup_max_cpus);
542 if (setup_max_cpus == 0)
543 arch_disable_smp_support();
544
545 return 0;
546}
547
548early_param("maxcpus", maxcpus);
549
550/* Setup number of possible processor ids */
551int nr_cpu_ids __read_mostly = NR_CPUS;
552EXPORT_SYMBOL(nr_cpu_ids);
553
554/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
555void __init setup_nr_cpu_ids(void)
556{
557 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
558}
559
560void __weak smp_announce(void)
561{
562 printk(KERN_INFO "Brought up %d CPUs\n", num_online_cpus());
563}
564
565/* Called by boot processor to activate the rest. */
566void __init smp_init(void)
567{
568 unsigned int cpu;
569
570 idle_threads_init();
571 cpuhp_threads_init();
572
573 /* FIXME: This should be done in userspace --RR */
574 for_each_present_cpu(cpu) {
575 if (num_online_cpus() >= setup_max_cpus)
576 break;
577 if (!cpu_online(cpu))
578 cpu_up(cpu);
579 }
580
581 /* Any cleanup work */
582 smp_announce();
583 smp_cpus_done(setup_max_cpus);
584}
585
586/*
587 * Call a function on all processors. May be used during early boot while
588 * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
589 * of local_irq_disable/enable().
590 */
591int on_each_cpu(void (*func) (void *info), void *info, int wait)
592{
593 unsigned long flags;
594 int ret = 0;
595
596 preempt_disable();
597 ret = smp_call_function(func, info, wait);
598 local_irq_save(flags);
599 func(info);
600 local_irq_restore(flags);
601 preempt_enable();
602 return ret;
603}
604EXPORT_SYMBOL(on_each_cpu);
605
606/**
607 * on_each_cpu_mask(): Run a function on processors specified by
608 * cpumask, which may include the local processor.
609 * @mask: The set of cpus to run on (only runs on online subset).
610 * @func: The function to run. This must be fast and non-blocking.
611 * @info: An arbitrary pointer to pass to the function.
612 * @wait: If true, wait (atomically) until function has completed
613 * on other CPUs.
614 *
615 * If @wait is true, then returns once @func has returned.
616 *
617 * You must not call this function with disabled interrupts or from a
618 * hardware interrupt handler or from a bottom half handler. The
619 * exception is that it may be used during early boot while
620 * early_boot_irqs_disabled is set.
621 */
622void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
623 void *info, bool wait)
624{
625 int cpu = get_cpu();
626
627 smp_call_function_many(mask, func, info, wait);
628 if (cpumask_test_cpu(cpu, mask)) {
629 unsigned long flags;
630 local_irq_save(flags);
631 func(info);
632 local_irq_restore(flags);
633 }
634 put_cpu();
635}
636EXPORT_SYMBOL(on_each_cpu_mask);
637
638/*
639 * on_each_cpu_cond(): Call a function on each processor for which
640 * the supplied function cond_func returns true, optionally waiting
641 * for all the required CPUs to finish. This may include the local
642 * processor.
643 * @cond_func: A callback function that is passed a cpu id and
644 * the the info parameter. The function is called
645 * with preemption disabled. The function should
646 * return a blooean value indicating whether to IPI
647 * the specified CPU.
648 * @func: The function to run on all applicable CPUs.
649 * This must be fast and non-blocking.
650 * @info: An arbitrary pointer to pass to both functions.
651 * @wait: If true, wait (atomically) until function has
652 * completed on other CPUs.
653 * @gfp_flags: GFP flags to use when allocating the cpumask
654 * used internally by the function.
655 *
656 * The function might sleep if the GFP flags indicates a non
657 * atomic allocation is allowed.
658 *
659 * Preemption is disabled to protect against CPUs going offline but not online.
660 * CPUs going online during the call will not be seen or sent an IPI.
661 *
662 * You must not call this function with disabled interrupts or
663 * from a hardware interrupt handler or from a bottom half handler.
664 */
665void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
666 smp_call_func_t func, void *info, bool wait,
667 gfp_t gfp_flags)
668{
669 cpumask_var_t cpus;
670 int cpu, ret;
671
672 might_sleep_if(gfpflags_allow_blocking(gfp_flags));
673
674 if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
675 preempt_disable();
676 for_each_online_cpu(cpu)
677 if (cond_func(cpu, info))
678 cpumask_set_cpu(cpu, cpus);
679 on_each_cpu_mask(cpus, func, info, wait);
680 preempt_enable();
681 free_cpumask_var(cpus);
682 } else {
683 /*
684 * No free cpumask, bother. No matter, we'll
685 * just have to IPI them one by one.
686 */
687 preempt_disable();
688 for_each_online_cpu(cpu)
689 if (cond_func(cpu, info)) {
690 ret = smp_call_function_single(cpu, func,
691 info, wait);
692 WARN_ON_ONCE(ret);
693 }
694 preempt_enable();
695 }
696}
697EXPORT_SYMBOL(on_each_cpu_cond);
698
699static void do_nothing(void *unused)
700{
701}
702
703/**
704 * kick_all_cpus_sync - Force all cpus out of idle
705 *
706 * Used to synchronize the update of pm_idle function pointer. It's
707 * called after the pointer is updated and returns after the dummy
708 * callback function has been executed on all cpus. The execution of
709 * the function can only happen on the remote cpus after they have
710 * left the idle function which had been called via pm_idle function
711 * pointer. So it's guaranteed that nothing uses the previous pointer
712 * anymore.
713 */
714void kick_all_cpus_sync(void)
715{
716 /* Make sure the change is visible before we kick the cpus */
717 smp_mb();
718 smp_call_function(do_nothing, NULL, 1);
719}
720EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
721
722/**
723 * wake_up_all_idle_cpus - break all cpus out of idle
724 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
725 * including idle polling cpus, for non-idle cpus, we will do nothing
726 * for them.
727 */
728void wake_up_all_idle_cpus(void)
729{
730 int cpu;
731
732 preempt_disable();
733 for_each_online_cpu(cpu) {
734 if (cpu == smp_processor_id())
735 continue;
736
737 wake_up_if_idle(cpu);
738 }
739 preempt_enable();
740}
741EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);