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1/*
2 * Generic helpers for smp ipi calls
3 *
4 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
5 */
6#include <linux/rcupdate.h>
7#include <linux/rculist.h>
8#include <linux/kernel.h>
9#include <linux/export.h>
10#include <linux/percpu.h>
11#include <linux/init.h>
12#include <linux/gfp.h>
13#include <linux/smp.h>
14#include <linux/cpu.h>
15
16#include "smpboot.h"
17
18#ifdef CONFIG_USE_GENERIC_SMP_HELPERS
19static struct {
20 struct list_head queue;
21 raw_spinlock_t lock;
22} call_function __cacheline_aligned_in_smp =
23 {
24 .queue = LIST_HEAD_INIT(call_function.queue),
25 .lock = __RAW_SPIN_LOCK_UNLOCKED(call_function.lock),
26 };
27
28enum {
29 CSD_FLAG_LOCK = 0x01,
30};
31
32struct call_function_data {
33 struct call_single_data csd;
34 atomic_t refs;
35 cpumask_var_t cpumask;
36};
37
38static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data);
39
40struct call_single_queue {
41 struct list_head list;
42 raw_spinlock_t lock;
43};
44
45static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_queue, call_single_queue);
46
47static int
48hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
49{
50 long cpu = (long)hcpu;
51 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
52
53 switch (action) {
54 case CPU_UP_PREPARE:
55 case CPU_UP_PREPARE_FROZEN:
56 if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
57 cpu_to_node(cpu)))
58 return notifier_from_errno(-ENOMEM);
59 break;
60
61#ifdef CONFIG_HOTPLUG_CPU
62 case CPU_UP_CANCELED:
63 case CPU_UP_CANCELED_FROZEN:
64
65 case CPU_DEAD:
66 case CPU_DEAD_FROZEN:
67 free_cpumask_var(cfd->cpumask);
68 break;
69#endif
70 };
71
72 return NOTIFY_OK;
73}
74
75static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
76 .notifier_call = hotplug_cfd,
77};
78
79void __init call_function_init(void)
80{
81 void *cpu = (void *)(long)smp_processor_id();
82 int i;
83
84 for_each_possible_cpu(i) {
85 struct call_single_queue *q = &per_cpu(call_single_queue, i);
86
87 raw_spin_lock_init(&q->lock);
88 INIT_LIST_HEAD(&q->list);
89 }
90
91 hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
92 register_cpu_notifier(&hotplug_cfd_notifier);
93}
94
95/*
96 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
97 *
98 * For non-synchronous ipi calls the csd can still be in use by the
99 * previous function call. For multi-cpu calls its even more interesting
100 * as we'll have to ensure no other cpu is observing our csd.
101 */
102static void csd_lock_wait(struct call_single_data *data)
103{
104 while (data->flags & CSD_FLAG_LOCK)
105 cpu_relax();
106}
107
108static void csd_lock(struct call_single_data *data)
109{
110 csd_lock_wait(data);
111 data->flags = CSD_FLAG_LOCK;
112
113 /*
114 * prevent CPU from reordering the above assignment
115 * to ->flags with any subsequent assignments to other
116 * fields of the specified call_single_data structure:
117 */
118 smp_mb();
119}
120
121static void csd_unlock(struct call_single_data *data)
122{
123 WARN_ON(!(data->flags & CSD_FLAG_LOCK));
124
125 /*
126 * ensure we're all done before releasing data:
127 */
128 smp_mb();
129
130 data->flags &= ~CSD_FLAG_LOCK;
131}
132
133/*
134 * Insert a previously allocated call_single_data element
135 * for execution on the given CPU. data must already have
136 * ->func, ->info, and ->flags set.
137 */
138static
139void generic_exec_single(int cpu, struct call_single_data *data, int wait)
140{
141 struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
142 unsigned long flags;
143 int ipi;
144
145 raw_spin_lock_irqsave(&dst->lock, flags);
146 ipi = list_empty(&dst->list);
147 list_add_tail(&data->list, &dst->list);
148 raw_spin_unlock_irqrestore(&dst->lock, flags);
149
150 /*
151 * The list addition should be visible before sending the IPI
152 * handler locks the list to pull the entry off it because of
153 * normal cache coherency rules implied by spinlocks.
154 *
155 * If IPIs can go out of order to the cache coherency protocol
156 * in an architecture, sufficient synchronisation should be added
157 * to arch code to make it appear to obey cache coherency WRT
158 * locking and barrier primitives. Generic code isn't really
159 * equipped to do the right thing...
160 */
161 if (ipi)
162 arch_send_call_function_single_ipi(cpu);
163
164 if (wait)
165 csd_lock_wait(data);
166}
167
168/*
169 * Invoked by arch to handle an IPI for call function. Must be called with
170 * interrupts disabled.
171 */
172void generic_smp_call_function_interrupt(void)
173{
174 struct call_function_data *data;
175 int cpu = smp_processor_id();
176
177 /*
178 * Shouldn't receive this interrupt on a cpu that is not yet online.
179 */
180 WARN_ON_ONCE(!cpu_online(cpu));
181
182 /*
183 * Ensure entry is visible on call_function_queue after we have
184 * entered the IPI. See comment in smp_call_function_many.
185 * If we don't have this, then we may miss an entry on the list
186 * and never get another IPI to process it.
187 */
188 smp_mb();
189
190 /*
191 * It's ok to use list_for_each_rcu() here even though we may
192 * delete 'pos', since list_del_rcu() doesn't clear ->next
193 */
194 list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
195 int refs;
196 smp_call_func_t func;
197
198 /*
199 * Since we walk the list without any locks, we might
200 * see an entry that was completed, removed from the
201 * list and is in the process of being reused.
202 *
203 * We must check that the cpu is in the cpumask before
204 * checking the refs, and both must be set before
205 * executing the callback on this cpu.
206 */
207
208 if (!cpumask_test_cpu(cpu, data->cpumask))
209 continue;
210
211 smp_rmb();
212
213 if (atomic_read(&data->refs) == 0)
214 continue;
215
216 func = data->csd.func; /* save for later warn */
217 func(data->csd.info);
218
219 /*
220 * If the cpu mask is not still set then func enabled
221 * interrupts (BUG), and this cpu took another smp call
222 * function interrupt and executed func(info) twice
223 * on this cpu. That nested execution decremented refs.
224 */
225 if (!cpumask_test_and_clear_cpu(cpu, data->cpumask)) {
226 WARN(1, "%pf enabled interrupts and double executed\n", func);
227 continue;
228 }
229
230 refs = atomic_dec_return(&data->refs);
231 WARN_ON(refs < 0);
232
233 if (refs)
234 continue;
235
236 WARN_ON(!cpumask_empty(data->cpumask));
237
238 raw_spin_lock(&call_function.lock);
239 list_del_rcu(&data->csd.list);
240 raw_spin_unlock(&call_function.lock);
241
242 csd_unlock(&data->csd);
243 }
244
245}
246
247/*
248 * Invoked by arch to handle an IPI for call function single. Must be
249 * called from the arch with interrupts disabled.
250 */
251void generic_smp_call_function_single_interrupt(void)
252{
253 struct call_single_queue *q = &__get_cpu_var(call_single_queue);
254 unsigned int data_flags;
255 LIST_HEAD(list);
256
257 /*
258 * Shouldn't receive this interrupt on a cpu that is not yet online.
259 */
260 WARN_ON_ONCE(!cpu_online(smp_processor_id()));
261
262 raw_spin_lock(&q->lock);
263 list_replace_init(&q->list, &list);
264 raw_spin_unlock(&q->lock);
265
266 while (!list_empty(&list)) {
267 struct call_single_data *data;
268
269 data = list_entry(list.next, struct call_single_data, list);
270 list_del(&data->list);
271
272 /*
273 * 'data' can be invalid after this call if flags == 0
274 * (when called through generic_exec_single()),
275 * so save them away before making the call:
276 */
277 data_flags = data->flags;
278
279 data->func(data->info);
280
281 /*
282 * Unlocked CSDs are valid through generic_exec_single():
283 */
284 if (data_flags & CSD_FLAG_LOCK)
285 csd_unlock(data);
286 }
287}
288
289static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
290
291/*
292 * smp_call_function_single - Run a function on a specific CPU
293 * @func: The function to run. This must be fast and non-blocking.
294 * @info: An arbitrary pointer to pass to the function.
295 * @wait: If true, wait until function has completed on other CPUs.
296 *
297 * Returns 0 on success, else a negative status code.
298 */
299int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
300 int wait)
301{
302 struct call_single_data d = {
303 .flags = 0,
304 };
305 unsigned long flags;
306 int this_cpu;
307 int err = 0;
308
309 /*
310 * prevent preemption and reschedule on another processor,
311 * as well as CPU removal
312 */
313 this_cpu = get_cpu();
314
315 /*
316 * Can deadlock when called with interrupts disabled.
317 * We allow cpu's that are not yet online though, as no one else can
318 * send smp call function interrupt to this cpu and as such deadlocks
319 * can't happen.
320 */
321 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
322 && !oops_in_progress);
323
324 if (cpu == this_cpu) {
325 local_irq_save(flags);
326 func(info);
327 local_irq_restore(flags);
328 } else {
329 if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
330 struct call_single_data *data = &d;
331
332 if (!wait)
333 data = &__get_cpu_var(csd_data);
334
335 csd_lock(data);
336
337 data->func = func;
338 data->info = info;
339 generic_exec_single(cpu, data, wait);
340 } else {
341 err = -ENXIO; /* CPU not online */
342 }
343 }
344
345 put_cpu();
346
347 return err;
348}
349EXPORT_SYMBOL(smp_call_function_single);
350
351/*
352 * smp_call_function_any - Run a function on any of the given cpus
353 * @mask: The mask of cpus it can run on.
354 * @func: The function to run. This must be fast and non-blocking.
355 * @info: An arbitrary pointer to pass to the function.
356 * @wait: If true, wait until function has completed.
357 *
358 * Returns 0 on success, else a negative status code (if no cpus were online).
359 * Note that @wait will be implicitly turned on in case of allocation failures,
360 * since we fall back to on-stack allocation.
361 *
362 * Selection preference:
363 * 1) current cpu if in @mask
364 * 2) any cpu of current node if in @mask
365 * 3) any other online cpu in @mask
366 */
367int smp_call_function_any(const struct cpumask *mask,
368 smp_call_func_t func, void *info, int wait)
369{
370 unsigned int cpu;
371 const struct cpumask *nodemask;
372 int ret;
373
374 /* Try for same CPU (cheapest) */
375 cpu = get_cpu();
376 if (cpumask_test_cpu(cpu, mask))
377 goto call;
378
379 /* Try for same node. */
380 nodemask = cpumask_of_node(cpu_to_node(cpu));
381 for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
382 cpu = cpumask_next_and(cpu, nodemask, mask)) {
383 if (cpu_online(cpu))
384 goto call;
385 }
386
387 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
388 cpu = cpumask_any_and(mask, cpu_online_mask);
389call:
390 ret = smp_call_function_single(cpu, func, info, wait);
391 put_cpu();
392 return ret;
393}
394EXPORT_SYMBOL_GPL(smp_call_function_any);
395
396/**
397 * __smp_call_function_single(): Run a function on a specific CPU
398 * @cpu: The CPU to run on.
399 * @data: Pre-allocated and setup data structure
400 * @wait: If true, wait until function has completed on specified CPU.
401 *
402 * Like smp_call_function_single(), but allow caller to pass in a
403 * pre-allocated data structure. Useful for embedding @data inside
404 * other structures, for instance.
405 */
406void __smp_call_function_single(int cpu, struct call_single_data *data,
407 int wait)
408{
409 unsigned int this_cpu;
410 unsigned long flags;
411
412 this_cpu = get_cpu();
413 /*
414 * Can deadlock when called with interrupts disabled.
415 * We allow cpu's that are not yet online though, as no one else can
416 * send smp call function interrupt to this cpu and as such deadlocks
417 * can't happen.
418 */
419 WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
420 && !oops_in_progress);
421
422 if (cpu == this_cpu) {
423 local_irq_save(flags);
424 data->func(data->info);
425 local_irq_restore(flags);
426 } else {
427 csd_lock(data);
428 generic_exec_single(cpu, data, wait);
429 }
430 put_cpu();
431}
432
433/**
434 * smp_call_function_many(): Run a function on a set of other CPUs.
435 * @mask: The set of cpus to run on (only runs on online subset).
436 * @func: The function to run. This must be fast and non-blocking.
437 * @info: An arbitrary pointer to pass to the function.
438 * @wait: If true, wait (atomically) until function has completed
439 * on other CPUs.
440 *
441 * If @wait is true, then returns once @func has returned.
442 *
443 * You must not call this function with disabled interrupts or from a
444 * hardware interrupt handler or from a bottom half handler. Preemption
445 * must be disabled when calling this function.
446 */
447void smp_call_function_many(const struct cpumask *mask,
448 smp_call_func_t func, void *info, bool wait)
449{
450 struct call_function_data *data;
451 unsigned long flags;
452 int refs, cpu, next_cpu, this_cpu = smp_processor_id();
453
454 /*
455 * Can deadlock when called with interrupts disabled.
456 * We allow cpu's that are not yet online though, as no one else can
457 * send smp call function interrupt to this cpu and as such deadlocks
458 * can't happen.
459 */
460 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
461 && !oops_in_progress && !early_boot_irqs_disabled);
462
463 /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
464 cpu = cpumask_first_and(mask, cpu_online_mask);
465 if (cpu == this_cpu)
466 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
467
468 /* No online cpus? We're done. */
469 if (cpu >= nr_cpu_ids)
470 return;
471
472 /* Do we have another CPU which isn't us? */
473 next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
474 if (next_cpu == this_cpu)
475 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
476
477 /* Fastpath: do that cpu by itself. */
478 if (next_cpu >= nr_cpu_ids) {
479 smp_call_function_single(cpu, func, info, wait);
480 return;
481 }
482
483 data = &__get_cpu_var(cfd_data);
484 csd_lock(&data->csd);
485
486 /* This BUG_ON verifies our reuse assertions and can be removed */
487 BUG_ON(atomic_read(&data->refs) || !cpumask_empty(data->cpumask));
488
489 /*
490 * The global call function queue list add and delete are protected
491 * by a lock, but the list is traversed without any lock, relying
492 * on the rcu list add and delete to allow safe concurrent traversal.
493 * We reuse the call function data without waiting for any grace
494 * period after some other cpu removes it from the global queue.
495 * This means a cpu might find our data block as it is being
496 * filled out.
497 *
498 * We hold off the interrupt handler on the other cpu by
499 * ordering our writes to the cpu mask vs our setting of the
500 * refs counter. We assert only the cpu owning the data block
501 * will set a bit in cpumask, and each bit will only be cleared
502 * by the subject cpu. Each cpu must first find its bit is
503 * set and then check that refs is set indicating the element is
504 * ready to be processed, otherwise it must skip the entry.
505 *
506 * On the previous iteration refs was set to 0 by another cpu.
507 * To avoid the use of transitivity, set the counter to 0 here
508 * so the wmb will pair with the rmb in the interrupt handler.
509 */
510 atomic_set(&data->refs, 0); /* convert 3rd to 1st party write */
511
512 data->csd.func = func;
513 data->csd.info = info;
514
515 /* Ensure 0 refs is visible before mask. Also orders func and info */
516 smp_wmb();
517
518 /* We rely on the "and" being processed before the store */
519 cpumask_and(data->cpumask, mask, cpu_online_mask);
520 cpumask_clear_cpu(this_cpu, data->cpumask);
521 refs = cpumask_weight(data->cpumask);
522
523 /* Some callers race with other cpus changing the passed mask */
524 if (unlikely(!refs)) {
525 csd_unlock(&data->csd);
526 return;
527 }
528
529 raw_spin_lock_irqsave(&call_function.lock, flags);
530 /*
531 * Place entry at the _HEAD_ of the list, so that any cpu still
532 * observing the entry in generic_smp_call_function_interrupt()
533 * will not miss any other list entries:
534 */
535 list_add_rcu(&data->csd.list, &call_function.queue);
536 /*
537 * We rely on the wmb() in list_add_rcu to complete our writes
538 * to the cpumask before this write to refs, which indicates
539 * data is on the list and is ready to be processed.
540 */
541 atomic_set(&data->refs, refs);
542 raw_spin_unlock_irqrestore(&call_function.lock, flags);
543
544 /*
545 * Make the list addition visible before sending the ipi.
546 * (IPIs must obey or appear to obey normal Linux cache
547 * coherency rules -- see comment in generic_exec_single).
548 */
549 smp_mb();
550
551 /* Send a message to all CPUs in the map */
552 arch_send_call_function_ipi_mask(data->cpumask);
553
554 /* Optionally wait for the CPUs to complete */
555 if (wait)
556 csd_lock_wait(&data->csd);
557}
558EXPORT_SYMBOL(smp_call_function_many);
559
560/**
561 * smp_call_function(): Run a function on all other CPUs.
562 * @func: The function to run. This must be fast and non-blocking.
563 * @info: An arbitrary pointer to pass to the function.
564 * @wait: If true, wait (atomically) until function has completed
565 * on other CPUs.
566 *
567 * Returns 0.
568 *
569 * If @wait is true, then returns once @func has returned; otherwise
570 * it returns just before the target cpu calls @func.
571 *
572 * You must not call this function with disabled interrupts or from a
573 * hardware interrupt handler or from a bottom half handler.
574 */
575int smp_call_function(smp_call_func_t func, void *info, int wait)
576{
577 preempt_disable();
578 smp_call_function_many(cpu_online_mask, func, info, wait);
579 preempt_enable();
580
581 return 0;
582}
583EXPORT_SYMBOL(smp_call_function);
584
585void ipi_call_lock(void)
586{
587 raw_spin_lock(&call_function.lock);
588}
589
590void ipi_call_unlock(void)
591{
592 raw_spin_unlock(&call_function.lock);
593}
594
595void ipi_call_lock_irq(void)
596{
597 raw_spin_lock_irq(&call_function.lock);
598}
599
600void ipi_call_unlock_irq(void)
601{
602 raw_spin_unlock_irq(&call_function.lock);
603}
604#endif /* USE_GENERIC_SMP_HELPERS */
605
606/* Setup configured maximum number of CPUs to activate */
607unsigned int setup_max_cpus = NR_CPUS;
608EXPORT_SYMBOL(setup_max_cpus);
609
610
611/*
612 * Setup routine for controlling SMP activation
613 *
614 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
615 * activation entirely (the MPS table probe still happens, though).
616 *
617 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
618 * greater than 0, limits the maximum number of CPUs activated in
619 * SMP mode to <NUM>.
620 */
621
622void __weak arch_disable_smp_support(void) { }
623
624static int __init nosmp(char *str)
625{
626 setup_max_cpus = 0;
627 arch_disable_smp_support();
628
629 return 0;
630}
631
632early_param("nosmp", nosmp);
633
634/* this is hard limit */
635static int __init nrcpus(char *str)
636{
637 int nr_cpus;
638
639 get_option(&str, &nr_cpus);
640 if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
641 nr_cpu_ids = nr_cpus;
642
643 return 0;
644}
645
646early_param("nr_cpus", nrcpus);
647
648static int __init maxcpus(char *str)
649{
650 get_option(&str, &setup_max_cpus);
651 if (setup_max_cpus == 0)
652 arch_disable_smp_support();
653
654 return 0;
655}
656
657early_param("maxcpus", maxcpus);
658
659/* Setup number of possible processor ids */
660int nr_cpu_ids __read_mostly = NR_CPUS;
661EXPORT_SYMBOL(nr_cpu_ids);
662
663/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
664void __init setup_nr_cpu_ids(void)
665{
666 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
667}
668
669/* Called by boot processor to activate the rest. */
670void __init smp_init(void)
671{
672 unsigned int cpu;
673
674 idle_threads_init();
675
676 /* FIXME: This should be done in userspace --RR */
677 for_each_present_cpu(cpu) {
678 if (num_online_cpus() >= setup_max_cpus)
679 break;
680 if (!cpu_online(cpu))
681 cpu_up(cpu);
682 }
683
684 /* Any cleanup work */
685 printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
686 smp_cpus_done(setup_max_cpus);
687}
688
689/*
690 * Call a function on all processors. May be used during early boot while
691 * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
692 * of local_irq_disable/enable().
693 */
694int on_each_cpu(void (*func) (void *info), void *info, int wait)
695{
696 unsigned long flags;
697 int ret = 0;
698
699 preempt_disable();
700 ret = smp_call_function(func, info, wait);
701 local_irq_save(flags);
702 func(info);
703 local_irq_restore(flags);
704 preempt_enable();
705 return ret;
706}
707EXPORT_SYMBOL(on_each_cpu);
708
709/**
710 * on_each_cpu_mask(): Run a function on processors specified by
711 * cpumask, which may include the local processor.
712 * @mask: The set of cpus to run on (only runs on online subset).
713 * @func: The function to run. This must be fast and non-blocking.
714 * @info: An arbitrary pointer to pass to the function.
715 * @wait: If true, wait (atomically) until function has completed
716 * on other CPUs.
717 *
718 * If @wait is true, then returns once @func has returned.
719 *
720 * You must not call this function with disabled interrupts or
721 * from a hardware interrupt handler or from a bottom half handler.
722 */
723void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
724 void *info, bool wait)
725{
726 int cpu = get_cpu();
727
728 smp_call_function_many(mask, func, info, wait);
729 if (cpumask_test_cpu(cpu, mask)) {
730 local_irq_disable();
731 func(info);
732 local_irq_enable();
733 }
734 put_cpu();
735}
736EXPORT_SYMBOL(on_each_cpu_mask);
737
738/*
739 * on_each_cpu_cond(): Call a function on each processor for which
740 * the supplied function cond_func returns true, optionally waiting
741 * for all the required CPUs to finish. This may include the local
742 * processor.
743 * @cond_func: A callback function that is passed a cpu id and
744 * the the info parameter. The function is called
745 * with preemption disabled. The function should
746 * return a blooean value indicating whether to IPI
747 * the specified CPU.
748 * @func: The function to run on all applicable CPUs.
749 * This must be fast and non-blocking.
750 * @info: An arbitrary pointer to pass to both functions.
751 * @wait: If true, wait (atomically) until function has
752 * completed on other CPUs.
753 * @gfp_flags: GFP flags to use when allocating the cpumask
754 * used internally by the function.
755 *
756 * The function might sleep if the GFP flags indicates a non
757 * atomic allocation is allowed.
758 *
759 * Preemption is disabled to protect against CPUs going offline but not online.
760 * CPUs going online during the call will not be seen or sent an IPI.
761 *
762 * You must not call this function with disabled interrupts or
763 * from a hardware interrupt handler or from a bottom half handler.
764 */
765void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
766 smp_call_func_t func, void *info, bool wait,
767 gfp_t gfp_flags)
768{
769 cpumask_var_t cpus;
770 int cpu, ret;
771
772 might_sleep_if(gfp_flags & __GFP_WAIT);
773
774 if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
775 preempt_disable();
776 for_each_online_cpu(cpu)
777 if (cond_func(cpu, info))
778 cpumask_set_cpu(cpu, cpus);
779 on_each_cpu_mask(cpus, func, info, wait);
780 preempt_enable();
781 free_cpumask_var(cpus);
782 } else {
783 /*
784 * No free cpumask, bother. No matter, we'll
785 * just have to IPI them one by one.
786 */
787 preempt_disable();
788 for_each_online_cpu(cpu)
789 if (cond_func(cpu, info)) {
790 ret = smp_call_function_single(cpu, func,
791 info, wait);
792 WARN_ON_ONCE(!ret);
793 }
794 preempt_enable();
795 }
796}
797EXPORT_SYMBOL(on_each_cpu_cond);
798
799static void do_nothing(void *unused)
800{
801}
802
803/**
804 * kick_all_cpus_sync - Force all cpus out of idle
805 *
806 * Used to synchronize the update of pm_idle function pointer. It's
807 * called after the pointer is updated and returns after the dummy
808 * callback function has been executed on all cpus. The execution of
809 * the function can only happen on the remote cpus after they have
810 * left the idle function which had been called via pm_idle function
811 * pointer. So it's guaranteed that nothing uses the previous pointer
812 * anymore.
813 */
814void kick_all_cpus_sync(void)
815{
816 /* Make sure the change is visible before we kick the cpus */
817 smp_mb();
818 smp_call_function(do_nothing, NULL, 1);
819}
820EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
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);