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3d442233
JA
1/*
2 * Generic helpers for smp ipi calls
3 *
4 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
3d442233 5 */
3d442233 6#include <linux/rcupdate.h>
59190f42 7#include <linux/rculist.h>
641cd4cf 8#include <linux/kernel.h>
9984de1a 9#include <linux/export.h>
0b13fda1
IM
10#include <linux/percpu.h>
11#include <linux/init.h>
5a0e3ad6 12#include <linux/gfp.h>
3d442233 13#include <linux/smp.h>
8969a5ed 14#include <linux/cpu.h>
3d442233 15
3bb5d2ee
SS
16#include "smpboot.h"
17
351f8f8e 18#ifdef CONFIG_USE_GENERIC_SMP_HELPERS
3d442233 19enum {
6e275637 20 CSD_FLAG_LOCK = 0x01,
3d442233
JA
21};
22
23struct call_function_data {
9a46ad6d 24 struct call_single_data __percpu *csd;
0b13fda1 25 cpumask_var_t cpumask;
f44310b9 26 cpumask_var_t cpumask_ipi;
3d442233
JA
27};
28
e03bcb68
MM
29static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data);
30
3d442233 31struct call_single_queue {
0b13fda1 32 struct list_head list;
9f5a5621 33 raw_spinlock_t lock;
3d442233
JA
34};
35
e03bcb68 36static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_queue, call_single_queue);
8969a5ed
PZ
37
38static int
39hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
40{
41 long cpu = (long)hcpu;
42 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
43
44 switch (action) {
45 case CPU_UP_PREPARE:
46 case CPU_UP_PREPARE_FROZEN:
eaa95840 47 if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
8969a5ed 48 cpu_to_node(cpu)))
80b5184c 49 return notifier_from_errno(-ENOMEM);
f44310b9
WY
50 if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
51 cpu_to_node(cpu)))
52 return notifier_from_errno(-ENOMEM);
9a46ad6d
SL
53 cfd->csd = alloc_percpu(struct call_single_data);
54 if (!cfd->csd) {
55 free_cpumask_var(cfd->cpumask);
56 return notifier_from_errno(-ENOMEM);
57 }
8969a5ed
PZ
58 break;
59
69dd647f 60#ifdef CONFIG_HOTPLUG_CPU
8969a5ed
PZ
61 case CPU_UP_CANCELED:
62 case CPU_UP_CANCELED_FROZEN:
63
64 case CPU_DEAD:
65 case CPU_DEAD_FROZEN:
66 free_cpumask_var(cfd->cpumask);
f44310b9 67 free_cpumask_var(cfd->cpumask_ipi);
9a46ad6d 68 free_percpu(cfd->csd);
8969a5ed
PZ
69 break;
70#endif
71 };
72
73 return NOTIFY_OK;
74}
75
76static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
0b13fda1 77 .notifier_call = hotplug_cfd,
8969a5ed
PZ
78};
79
d8ad7d11 80void __init call_function_init(void)
3d442233 81{
8969a5ed 82 void *cpu = (void *)(long)smp_processor_id();
3d442233
JA
83 int i;
84
85 for_each_possible_cpu(i) {
86 struct call_single_queue *q = &per_cpu(call_single_queue, i);
87
9f5a5621 88 raw_spin_lock_init(&q->lock);
3d442233
JA
89 INIT_LIST_HEAD(&q->list);
90 }
8969a5ed
PZ
91
92 hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
93 register_cpu_notifier(&hotplug_cfd_notifier);
3d442233
JA
94}
95
8969a5ed
PZ
96/*
97 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
98 *
0b13fda1
IM
99 * For non-synchronous ipi calls the csd can still be in use by the
100 * previous function call. For multi-cpu calls its even more interesting
101 * as we'll have to ensure no other cpu is observing our csd.
8969a5ed 102 */
e1d12f32 103static void csd_lock_wait(struct call_single_data *csd)
8969a5ed 104{
e1d12f32 105 while (csd->flags & CSD_FLAG_LOCK)
8969a5ed 106 cpu_relax();
6e275637
PZ
107}
108
e1d12f32 109static void csd_lock(struct call_single_data *csd)
6e275637 110{
e1d12f32
AM
111 csd_lock_wait(csd);
112 csd->flags |= CSD_FLAG_LOCK;
8969a5ed
PZ
113
114 /*
0b13fda1
IM
115 * prevent CPU from reordering the above assignment
116 * to ->flags with any subsequent assignments to other
117 * fields of the specified call_single_data structure:
8969a5ed 118 */
8969a5ed
PZ
119 smp_mb();
120}
121
e1d12f32 122static void csd_unlock(struct call_single_data *csd)
8969a5ed 123{
e1d12f32 124 WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
0b13fda1 125
8969a5ed 126 /*
0b13fda1 127 * ensure we're all done before releasing data:
8969a5ed
PZ
128 */
129 smp_mb();
0b13fda1 130
e1d12f32 131 csd->flags &= ~CSD_FLAG_LOCK;
3d442233
JA
132}
133
134/*
0b13fda1
IM
135 * Insert a previously allocated call_single_data element
136 * for execution on the given CPU. data must already have
137 * ->func, ->info, and ->flags set.
3d442233 138 */
6e275637 139static
e1d12f32 140void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
3d442233
JA
141{
142 struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
3d442233 143 unsigned long flags;
6e275637 144 int ipi;
3d442233 145
9f5a5621 146 raw_spin_lock_irqsave(&dst->lock, flags);
3d442233 147 ipi = list_empty(&dst->list);
e1d12f32 148 list_add_tail(&csd->list, &dst->list);
9f5a5621 149 raw_spin_unlock_irqrestore(&dst->lock, flags);
3d442233 150
561920a0 151 /*
15d0d3b3
NP
152 * The list addition should be visible before sending the IPI
153 * handler locks the list to pull the entry off it because of
154 * normal cache coherency rules implied by spinlocks.
155 *
156 * If IPIs can go out of order to the cache coherency protocol
157 * in an architecture, sufficient synchronisation should be added
158 * to arch code to make it appear to obey cache coherency WRT
0b13fda1
IM
159 * locking and barrier primitives. Generic code isn't really
160 * equipped to do the right thing...
561920a0 161 */
3d442233
JA
162 if (ipi)
163 arch_send_call_function_single_ipi(cpu);
164
165 if (wait)
e1d12f32 166 csd_lock_wait(csd);
3d442233
JA
167}
168
3d442233 169/*
0b13fda1
IM
170 * Invoked by arch to handle an IPI for call function single. Must be
171 * called from the arch with interrupts disabled.
3d442233
JA
172 */
173void generic_smp_call_function_single_interrupt(void)
174{
175 struct call_single_queue *q = &__get_cpu_var(call_single_queue);
0b13fda1 176 LIST_HEAD(list);
3d442233 177
269c861b
SS
178 /*
179 * Shouldn't receive this interrupt on a cpu that is not yet online.
180 */
181 WARN_ON_ONCE(!cpu_online(smp_processor_id()));
182
9f5a5621 183 raw_spin_lock(&q->lock);
15d0d3b3 184 list_replace_init(&q->list, &list);
9f5a5621 185 raw_spin_unlock(&q->lock);
3d442233 186
15d0d3b3 187 while (!list_empty(&list)) {
e1d12f32
AM
188 struct call_single_data *csd;
189 unsigned int csd_flags;
3d442233 190
e1d12f32
AM
191 csd = list_entry(list.next, struct call_single_data, list);
192 list_del(&csd->list);
3d442233 193
3d442233 194 /*
e1d12f32 195 * 'csd' can be invalid after this call if flags == 0
0b13fda1
IM
196 * (when called through generic_exec_single()),
197 * so save them away before making the call:
3d442233 198 */
e1d12f32 199 csd_flags = csd->flags;
15d0d3b3 200
e1d12f32 201 csd->func(csd->info);
15d0d3b3 202
8969a5ed 203 /*
0b13fda1 204 * Unlocked CSDs are valid through generic_exec_single():
8969a5ed 205 */
e1d12f32
AM
206 if (csd_flags & CSD_FLAG_LOCK)
207 csd_unlock(csd);
3d442233
JA
208 }
209}
210
e03bcb68 211static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
d7240b98 212
3d442233
JA
213/*
214 * smp_call_function_single - Run a function on a specific CPU
215 * @func: The function to run. This must be fast and non-blocking.
216 * @info: An arbitrary pointer to pass to the function.
3d442233
JA
217 * @wait: If true, wait until function has completed on other CPUs.
218 *
72f279b2 219 * Returns 0 on success, else a negative status code.
3d442233 220 */
3a5f65df 221int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
8691e5a8 222 int wait)
3d442233 223{
8969a5ed
PZ
224 struct call_single_data d = {
225 .flags = 0,
226 };
3d442233 227 unsigned long flags;
0b13fda1 228 int this_cpu;
f73be6de 229 int err = 0;
3d442233 230
0b13fda1
IM
231 /*
232 * prevent preemption and reschedule on another processor,
233 * as well as CPU removal
234 */
235 this_cpu = get_cpu();
236
269c861b
SS
237 /*
238 * Can deadlock when called with interrupts disabled.
239 * We allow cpu's that are not yet online though, as no one else can
240 * send smp call function interrupt to this cpu and as such deadlocks
241 * can't happen.
242 */
243 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
244 && !oops_in_progress);
3d442233 245
0b13fda1 246 if (cpu == this_cpu) {
3d442233
JA
247 local_irq_save(flags);
248 func(info);
249 local_irq_restore(flags);
0b13fda1
IM
250 } else {
251 if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
e1d12f32 252 struct call_single_data *csd = &d;
3d442233 253
0b13fda1 254 if (!wait)
e1d12f32 255 csd = &__get_cpu_var(csd_data);
6e275637 256
e1d12f32 257 csd_lock(csd);
3d442233 258
e1d12f32
AM
259 csd->func = func;
260 csd->info = info;
261 generic_exec_single(cpu, csd, wait);
0b13fda1
IM
262 } else {
263 err = -ENXIO; /* CPU not online */
264 }
3d442233
JA
265 }
266
267 put_cpu();
0b13fda1 268
f73be6de 269 return err;
3d442233
JA
270}
271EXPORT_SYMBOL(smp_call_function_single);
272
2ea6dec4
RR
273/*
274 * smp_call_function_any - Run a function on any of the given cpus
275 * @mask: The mask of cpus it can run on.
276 * @func: The function to run. This must be fast and non-blocking.
277 * @info: An arbitrary pointer to pass to the function.
278 * @wait: If true, wait until function has completed.
279 *
280 * Returns 0 on success, else a negative status code (if no cpus were online).
281 * Note that @wait will be implicitly turned on in case of allocation failures,
282 * since we fall back to on-stack allocation.
283 *
284 * Selection preference:
285 * 1) current cpu if in @mask
286 * 2) any cpu of current node if in @mask
287 * 3) any other online cpu in @mask
288 */
289int smp_call_function_any(const struct cpumask *mask,
3a5f65df 290 smp_call_func_t func, void *info, int wait)
2ea6dec4
RR
291{
292 unsigned int cpu;
293 const struct cpumask *nodemask;
294 int ret;
295
296 /* Try for same CPU (cheapest) */
297 cpu = get_cpu();
298 if (cpumask_test_cpu(cpu, mask))
299 goto call;
300
301 /* Try for same node. */
af2422c4 302 nodemask = cpumask_of_node(cpu_to_node(cpu));
2ea6dec4
RR
303 for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
304 cpu = cpumask_next_and(cpu, nodemask, mask)) {
305 if (cpu_online(cpu))
306 goto call;
307 }
308
309 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
310 cpu = cpumask_any_and(mask, cpu_online_mask);
311call:
312 ret = smp_call_function_single(cpu, func, info, wait);
313 put_cpu();
314 return ret;
315}
316EXPORT_SYMBOL_GPL(smp_call_function_any);
317
3d442233 318/**
27c379f7 319 * __smp_call_function_single(): Run a function on a specific CPU
3d442233
JA
320 * @cpu: The CPU to run on.
321 * @data: Pre-allocated and setup data structure
27c379f7 322 * @wait: If true, wait until function has completed on specified CPU.
3d442233 323 *
0b13fda1
IM
324 * Like smp_call_function_single(), but allow caller to pass in a
325 * pre-allocated data structure. Useful for embedding @data inside
326 * other structures, for instance.
3d442233 327 */
e1d12f32 328void __smp_call_function_single(int cpu, struct call_single_data *csd,
6e275637 329 int wait)
3d442233 330{
27c379f7
HC
331 unsigned int this_cpu;
332 unsigned long flags;
6e275637 333
27c379f7 334 this_cpu = get_cpu();
269c861b
SS
335 /*
336 * Can deadlock when called with interrupts disabled.
337 * We allow cpu's that are not yet online though, as no one else can
338 * send smp call function interrupt to this cpu and as such deadlocks
339 * can't happen.
340 */
341 WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
342 && !oops_in_progress);
3d442233 343
27c379f7
HC
344 if (cpu == this_cpu) {
345 local_irq_save(flags);
e1d12f32 346 csd->func(csd->info);
27c379f7
HC
347 local_irq_restore(flags);
348 } else {
e1d12f32
AM
349 csd_lock(csd);
350 generic_exec_single(cpu, csd, wait);
27c379f7
HC
351 }
352 put_cpu();
3d442233
JA
353}
354
355/**
54b11e6d
RR
356 * smp_call_function_many(): Run a function on a set of other CPUs.
357 * @mask: The set of cpus to run on (only runs on online subset).
3d442233
JA
358 * @func: The function to run. This must be fast and non-blocking.
359 * @info: An arbitrary pointer to pass to the function.
0b13fda1
IM
360 * @wait: If true, wait (atomically) until function has completed
361 * on other CPUs.
3d442233 362 *
72f279b2 363 * If @wait is true, then returns once @func has returned.
3d442233
JA
364 *
365 * You must not call this function with disabled interrupts or from a
366 * hardware interrupt handler or from a bottom half handler. Preemption
367 * must be disabled when calling this function.
368 */
54b11e6d 369void smp_call_function_many(const struct cpumask *mask,
3a5f65df 370 smp_call_func_t func, void *info, bool wait)
3d442233 371{
e1d12f32 372 struct call_function_data *cfd;
9a46ad6d 373 int cpu, next_cpu, this_cpu = smp_processor_id();
3d442233 374
269c861b
SS
375 /*
376 * Can deadlock when called with interrupts disabled.
377 * We allow cpu's that are not yet online though, as no one else can
378 * send smp call function interrupt to this cpu and as such deadlocks
379 * can't happen.
380 */
381 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
bd924e8c 382 && !oops_in_progress && !early_boot_irqs_disabled);
3d442233 383
723aae25 384 /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
54b11e6d 385 cpu = cpumask_first_and(mask, cpu_online_mask);
0b13fda1 386 if (cpu == this_cpu)
54b11e6d 387 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
0b13fda1 388
54b11e6d
RR
389 /* No online cpus? We're done. */
390 if (cpu >= nr_cpu_ids)
391 return;
392
393 /* Do we have another CPU which isn't us? */
394 next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
0b13fda1 395 if (next_cpu == this_cpu)
54b11e6d
RR
396 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
397
398 /* Fastpath: do that cpu by itself. */
399 if (next_cpu >= nr_cpu_ids) {
400 smp_call_function_single(cpu, func, info, wait);
401 return;
3d442233
JA
402 }
403
e1d12f32 404 cfd = &__get_cpu_var(cfd_data);
45a57919 405
e1d12f32
AM
406 cpumask_and(cfd->cpumask, mask, cpu_online_mask);
407 cpumask_clear_cpu(this_cpu, cfd->cpumask);
723aae25
MM
408
409 /* Some callers race with other cpus changing the passed mask */
e1d12f32 410 if (unlikely(!cpumask_weight(cfd->cpumask)))
723aae25 411 return;
3d442233 412
f44310b9 413 /*
e1d12f32
AM
414 * After we put an entry into the list, cfd->cpumask may be cleared
415 * again when another CPU sends another IPI for a SMP function call, so
416 * cfd->cpumask will be zero.
f44310b9 417 */
e1d12f32 418 cpumask_copy(cfd->cpumask_ipi, cfd->cpumask);
3d442233 419
e1d12f32
AM
420 for_each_cpu(cpu, cfd->cpumask) {
421 struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu);
9a46ad6d
SL
422 struct call_single_queue *dst =
423 &per_cpu(call_single_queue, cpu);
424 unsigned long flags;
425
426 csd_lock(csd);
427 csd->func = func;
428 csd->info = info;
429
430 raw_spin_lock_irqsave(&dst->lock, flags);
431 list_add_tail(&csd->list, &dst->list);
432 raw_spin_unlock_irqrestore(&dst->lock, flags);
433 }
561920a0 434
3d442233 435 /* Send a message to all CPUs in the map */
e1d12f32 436 arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
3d442233 437
9a46ad6d 438 if (wait) {
e1d12f32
AM
439 for_each_cpu(cpu, cfd->cpumask) {
440 struct call_single_data *csd;
441
442 csd = per_cpu_ptr(cfd->csd, cpu);
9a46ad6d
SL
443 csd_lock_wait(csd);
444 }
445 }
3d442233 446}
54b11e6d 447EXPORT_SYMBOL(smp_call_function_many);
3d442233
JA
448
449/**
450 * smp_call_function(): Run a function on all other CPUs.
451 * @func: The function to run. This must be fast and non-blocking.
452 * @info: An arbitrary pointer to pass to the function.
0b13fda1
IM
453 * @wait: If true, wait (atomically) until function has completed
454 * on other CPUs.
3d442233 455 *
54b11e6d 456 * Returns 0.
3d442233
JA
457 *
458 * If @wait is true, then returns once @func has returned; otherwise
72f279b2 459 * it returns just before the target cpu calls @func.
3d442233
JA
460 *
461 * You must not call this function with disabled interrupts or from a
462 * hardware interrupt handler or from a bottom half handler.
463 */
3a5f65df 464int smp_call_function(smp_call_func_t func, void *info, int wait)
3d442233 465{
3d442233 466 preempt_disable();
54b11e6d 467 smp_call_function_many(cpu_online_mask, func, info, wait);
3d442233 468 preempt_enable();
0b13fda1 469
54b11e6d 470 return 0;
3d442233
JA
471}
472EXPORT_SYMBOL(smp_call_function);
351f8f8e
AW
473#endif /* USE_GENERIC_SMP_HELPERS */
474
34db18a0
AW
475/* Setup configured maximum number of CPUs to activate */
476unsigned int setup_max_cpus = NR_CPUS;
477EXPORT_SYMBOL(setup_max_cpus);
478
479
480/*
481 * Setup routine for controlling SMP activation
482 *
483 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
484 * activation entirely (the MPS table probe still happens, though).
485 *
486 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
487 * greater than 0, limits the maximum number of CPUs activated in
488 * SMP mode to <NUM>.
489 */
490
491void __weak arch_disable_smp_support(void) { }
492
493static int __init nosmp(char *str)
494{
495 setup_max_cpus = 0;
496 arch_disable_smp_support();
497
498 return 0;
499}
500
501early_param("nosmp", nosmp);
502
503/* this is hard limit */
504static int __init nrcpus(char *str)
505{
506 int nr_cpus;
507
508 get_option(&str, &nr_cpus);
509 if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
510 nr_cpu_ids = nr_cpus;
511
512 return 0;
513}
514
515early_param("nr_cpus", nrcpus);
516
517static int __init maxcpus(char *str)
518{
519 get_option(&str, &setup_max_cpus);
520 if (setup_max_cpus == 0)
521 arch_disable_smp_support();
522
523 return 0;
524}
525
526early_param("maxcpus", maxcpus);
527
528/* Setup number of possible processor ids */
529int nr_cpu_ids __read_mostly = NR_CPUS;
530EXPORT_SYMBOL(nr_cpu_ids);
531
532/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
533void __init setup_nr_cpu_ids(void)
534{
535 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
536}
537
538/* Called by boot processor to activate the rest. */
539void __init smp_init(void)
540{
541 unsigned int cpu;
542
3bb5d2ee
SS
543 idle_threads_init();
544
34db18a0
AW
545 /* FIXME: This should be done in userspace --RR */
546 for_each_present_cpu(cpu) {
547 if (num_online_cpus() >= setup_max_cpus)
548 break;
549 if (!cpu_online(cpu))
550 cpu_up(cpu);
551 }
552
553 /* Any cleanup work */
554 printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
555 smp_cpus_done(setup_max_cpus);
556}
557
351f8f8e 558/*
bd924e8c
TH
559 * Call a function on all processors. May be used during early boot while
560 * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
561 * of local_irq_disable/enable().
351f8f8e
AW
562 */
563int on_each_cpu(void (*func) (void *info), void *info, int wait)
564{
bd924e8c 565 unsigned long flags;
351f8f8e
AW
566 int ret = 0;
567
568 preempt_disable();
569 ret = smp_call_function(func, info, wait);
bd924e8c 570 local_irq_save(flags);
351f8f8e 571 func(info);
bd924e8c 572 local_irq_restore(flags);
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573 preempt_enable();
574 return ret;
575}
576EXPORT_SYMBOL(on_each_cpu);
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577
578/**
579 * on_each_cpu_mask(): Run a function on processors specified by
580 * cpumask, which may include the local processor.
581 * @mask: The set of cpus to run on (only runs on online subset).
582 * @func: The function to run. This must be fast and non-blocking.
583 * @info: An arbitrary pointer to pass to the function.
584 * @wait: If true, wait (atomically) until function has completed
585 * on other CPUs.
586 *
587 * If @wait is true, then returns once @func has returned.
588 *
589 * You must not call this function with disabled interrupts or
590 * from a hardware interrupt handler or from a bottom half handler.
591 */
592void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
593 void *info, bool wait)
594{
595 int cpu = get_cpu();
596
597 smp_call_function_many(mask, func, info, wait);
598 if (cpumask_test_cpu(cpu, mask)) {
599 local_irq_disable();
600 func(info);
601 local_irq_enable();
602 }
603 put_cpu();
604}
605EXPORT_SYMBOL(on_each_cpu_mask);
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606
607/*
608 * on_each_cpu_cond(): Call a function on each processor for which
609 * the supplied function cond_func returns true, optionally waiting
610 * for all the required CPUs to finish. This may include the local
611 * processor.
612 * @cond_func: A callback function that is passed a cpu id and
613 * the the info parameter. The function is called
614 * with preemption disabled. The function should
615 * return a blooean value indicating whether to IPI
616 * the specified CPU.
617 * @func: The function to run on all applicable CPUs.
618 * This must be fast and non-blocking.
619 * @info: An arbitrary pointer to pass to both functions.
620 * @wait: If true, wait (atomically) until function has
621 * completed on other CPUs.
622 * @gfp_flags: GFP flags to use when allocating the cpumask
623 * used internally by the function.
624 *
625 * The function might sleep if the GFP flags indicates a non
626 * atomic allocation is allowed.
627 *
628 * Preemption is disabled to protect against CPUs going offline but not online.
629 * CPUs going online during the call will not be seen or sent an IPI.
630 *
631 * You must not call this function with disabled interrupts or
632 * from a hardware interrupt handler or from a bottom half handler.
633 */
634void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
635 smp_call_func_t func, void *info, bool wait,
636 gfp_t gfp_flags)
637{
638 cpumask_var_t cpus;
639 int cpu, ret;
640
641 might_sleep_if(gfp_flags & __GFP_WAIT);
642
643 if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
644 preempt_disable();
645 for_each_online_cpu(cpu)
646 if (cond_func(cpu, info))
647 cpumask_set_cpu(cpu, cpus);
648 on_each_cpu_mask(cpus, func, info, wait);
649 preempt_enable();
650 free_cpumask_var(cpus);
651 } else {
652 /*
653 * No free cpumask, bother. No matter, we'll
654 * just have to IPI them one by one.
655 */
656 preempt_disable();
657 for_each_online_cpu(cpu)
658 if (cond_func(cpu, info)) {
659 ret = smp_call_function_single(cpu, func,
660 info, wait);
661 WARN_ON_ONCE(!ret);
662 }
663 preempt_enable();
664 }
665}
666EXPORT_SYMBOL(on_each_cpu_cond);
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667
668static void do_nothing(void *unused)
669{
670}
671
672/**
673 * kick_all_cpus_sync - Force all cpus out of idle
674 *
675 * Used to synchronize the update of pm_idle function pointer. It's
676 * called after the pointer is updated and returns after the dummy
677 * callback function has been executed on all cpus. The execution of
678 * the function can only happen on the remote cpus after they have
679 * left the idle function which had been called via pm_idle function
680 * pointer. So it's guaranteed that nothing uses the previous pointer
681 * anymore.
682 */
683void kick_all_cpus_sync(void)
684{
685 /* Make sure the change is visible before we kick the cpus */
686 smp_mb();
687 smp_call_function(do_nothing, NULL, 1);
688}
689EXPORT_SYMBOL_GPL(kick_all_cpus_sync);