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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 |
19 | enum { |
20 | CSD_FLAG_LOCK = 0x01, |
21 | }; |
22 | |
23 | struct call_function_data { |
24 | struct call_single_data __percpu *csd; |
25 | cpumask_var_t cpumask; |
26 | cpumask_var_t cpumask_ipi; |
27 | }; |
28 | |
29 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data); |
30 | |
31 | struct call_single_queue { |
32 | struct list_head list; |
33 | raw_spinlock_t lock; |
34 | }; |
35 | |
36 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_queue, call_single_queue); |
37 | |
38 | static int |
39 | hotplug_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: |
47 | if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, |
48 | cpu_to_node(cpu))) |
49 | return notifier_from_errno(-ENOMEM); |
50 | if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL, |
51 | cpu_to_node(cpu))) |
52 | return notifier_from_errno(-ENOMEM); |
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 | } |
58 | break; |
59 | |
60 | #ifdef CONFIG_HOTPLUG_CPU |
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); |
67 | free_cpumask_var(cfd->cpumask_ipi); |
68 | free_percpu(cfd->csd); |
69 | break; |
70 | #endif |
71 | }; |
72 | |
73 | return NOTIFY_OK; |
74 | } |
75 | |
76 | static struct notifier_block __cpuinitdata hotplug_cfd_notifier = { |
77 | .notifier_call = hotplug_cfd, |
78 | }; |
79 | |
80 | void __init call_function_init(void) |
81 | { |
82 | void *cpu = (void *)(long)smp_processor_id(); |
83 | int i; |
84 | |
85 | for_each_possible_cpu(i) { |
86 | struct call_single_queue *q = &per_cpu(call_single_queue, i); |
87 | |
88 | raw_spin_lock_init(&q->lock); |
89 | INIT_LIST_HEAD(&q->list); |
90 | } |
91 | |
92 | hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu); |
93 | register_cpu_notifier(&hotplug_cfd_notifier); |
94 | } |
95 | |
96 | /* |
97 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources |
98 | * |
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. |
102 | */ |
103 | static void csd_lock_wait(struct call_single_data *data) |
104 | { |
105 | while (data->flags & CSD_FLAG_LOCK) |
106 | cpu_relax(); |
107 | } |
108 | |
109 | static void csd_lock(struct call_single_data *data) |
110 | { |
111 | csd_lock_wait(data); |
112 | data->flags = CSD_FLAG_LOCK; |
113 | |
114 | /* |
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: |
118 | */ |
119 | smp_mb(); |
120 | } |
121 | |
122 | static void csd_unlock(struct call_single_data *data) |
123 | { |
124 | WARN_ON(!(data->flags & CSD_FLAG_LOCK)); |
125 | |
126 | /* |
127 | * ensure we're all done before releasing data: |
128 | */ |
129 | smp_mb(); |
130 | |
131 | data->flags &= ~CSD_FLAG_LOCK; |
132 | } |
133 | |
134 | /* |
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. |
138 | */ |
139 | static |
140 | void generic_exec_single(int cpu, struct call_single_data *data, int wait) |
141 | { |
142 | struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); |
143 | unsigned long flags; |
144 | int ipi; |
145 | |
146 | raw_spin_lock_irqsave(&dst->lock, flags); |
147 | ipi = list_empty(&dst->list); |
148 | list_add_tail(&data->list, &dst->list); |
149 | raw_spin_unlock_irqrestore(&dst->lock, flags); |
150 | |
151 | /* |
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 |
159 | * locking and barrier primitives. Generic code isn't really |
160 | * equipped to do the right thing... |
161 | */ |
162 | if (ipi) |
163 | arch_send_call_function_single_ipi(cpu); |
164 | |
165 | if (wait) |
166 | csd_lock_wait(data); |
167 | } |
168 | |
169 | /* |
170 | * Invoked by arch to handle an IPI for call function single. Must be |
171 | * called from the arch with interrupts disabled. |
172 | */ |
173 | void generic_smp_call_function_single_interrupt(void) |
174 | { |
175 | struct call_single_queue *q = &__get_cpu_var(call_single_queue); |
176 | unsigned int data_flags; |
177 | LIST_HEAD(list); |
178 | |
179 | /* |
180 | * Shouldn't receive this interrupt on a cpu that is not yet online. |
181 | */ |
182 | WARN_ON_ONCE(!cpu_online(smp_processor_id())); |
183 | |
184 | raw_spin_lock(&q->lock); |
185 | list_replace_init(&q->list, &list); |
186 | raw_spin_unlock(&q->lock); |
187 | |
188 | while (!list_empty(&list)) { |
189 | struct call_single_data *data; |
190 | |
191 | data = list_entry(list.next, struct call_single_data, list); |
192 | list_del(&data->list); |
193 | |
194 | /* |
195 | * 'data' can be invalid after this call if flags == 0 |
196 | * (when called through generic_exec_single()), |
197 | * so save them away before making the call: |
198 | */ |
199 | data_flags = data->flags; |
200 | |
201 | data->func(data->info); |
202 | |
203 | /* |
204 | * Unlocked CSDs are valid through generic_exec_single(): |
205 | */ |
206 | if (data_flags & CSD_FLAG_LOCK) |
207 | csd_unlock(data); |
208 | } |
209 | } |
210 | |
211 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data); |
212 | |
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. |
217 | * @wait: If true, wait until function has completed on other CPUs. |
218 | * |
219 | * Returns 0 on success, else a negative status code. |
220 | */ |
221 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info, |
222 | int wait) |
223 | { |
224 | struct call_single_data d = { |
225 | .flags = 0, |
226 | }; |
227 | unsigned long flags; |
228 | int this_cpu; |
229 | int err = 0; |
230 | |
231 | /* |
232 | * prevent preemption and reschedule on another processor, |
233 | * as well as CPU removal |
234 | */ |
235 | this_cpu = get_cpu(); |
236 | |
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); |
245 | |
246 | if (cpu == this_cpu) { |
247 | local_irq_save(flags); |
248 | func(info); |
249 | local_irq_restore(flags); |
250 | } else { |
251 | if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { |
252 | struct call_single_data *data = &d; |
253 | |
254 | if (!wait) |
255 | data = &__get_cpu_var(csd_data); |
256 | |
257 | csd_lock(data); |
258 | |
259 | data->func = func; |
260 | data->info = info; |
261 | generic_exec_single(cpu, data, wait); |
262 | } else { |
263 | err = -ENXIO; /* CPU not online */ |
264 | } |
265 | } |
266 | |
267 | put_cpu(); |
268 | |
269 | return err; |
270 | } |
271 | EXPORT_SYMBOL(smp_call_function_single); |
272 | |
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 | */ |
289 | int smp_call_function_any(const struct cpumask *mask, |
290 | smp_call_func_t func, void *info, int wait) |
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. */ |
302 | nodemask = cpumask_of_node(cpu_to_node(cpu)); |
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); |
311 | call: |
312 | ret = smp_call_function_single(cpu, func, info, wait); |
313 | put_cpu(); |
314 | return ret; |
315 | } |
316 | EXPORT_SYMBOL_GPL(smp_call_function_any); |
317 | |
318 | /** |
319 | * __smp_call_function_single(): Run a function on a specific CPU |
320 | * @cpu: The CPU to run on. |
321 | * @data: Pre-allocated and setup data structure |
322 | * @wait: If true, wait until function has completed on specified CPU. |
323 | * |
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. |
327 | */ |
328 | void __smp_call_function_single(int cpu, struct call_single_data *data, |
329 | int wait) |
330 | { |
331 | unsigned int this_cpu; |
332 | unsigned long flags; |
333 | |
334 | this_cpu = get_cpu(); |
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); |
343 | |
344 | if (cpu == this_cpu) { |
345 | local_irq_save(flags); |
346 | data->func(data->info); |
347 | local_irq_restore(flags); |
348 | } else { |
349 | csd_lock(data); |
350 | generic_exec_single(cpu, data, wait); |
351 | } |
352 | put_cpu(); |
353 | } |
354 | |
355 | /** |
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). |
358 | * @func: The function to run. This must be fast and non-blocking. |
359 | * @info: An arbitrary pointer to pass to the function. |
360 | * @wait: If true, wait (atomically) until function has completed |
361 | * on other CPUs. |
362 | * |
363 | * If @wait is true, then returns once @func has returned. |
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 | */ |
369 | void smp_call_function_many(const struct cpumask *mask, |
370 | smp_call_func_t func, void *info, bool wait) |
371 | { |
372 | struct call_function_data *data; |
373 | int cpu, next_cpu, this_cpu = smp_processor_id(); |
374 | |
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() |
382 | && !oops_in_progress && !early_boot_irqs_disabled); |
383 | |
384 | /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ |
385 | cpu = cpumask_first_and(mask, cpu_online_mask); |
386 | if (cpu == this_cpu) |
387 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask); |
388 | |
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); |
395 | if (next_cpu == this_cpu) |
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; |
402 | } |
403 | |
404 | data = &__get_cpu_var(cfd_data); |
405 | |
406 | cpumask_and(data->cpumask, mask, cpu_online_mask); |
407 | cpumask_clear_cpu(this_cpu, data->cpumask); |
408 | |
409 | /* Some callers race with other cpus changing the passed mask */ |
410 | if (unlikely(!cpumask_weight(data->cpumask))) |
411 | return; |
412 | |
413 | /* |
414 | * After we put an entry into the list, data->cpumask |
415 | * may be cleared again when another CPU sends another IPI for |
416 | * a SMP function call, so data->cpumask will be zero. |
417 | */ |
418 | cpumask_copy(data->cpumask_ipi, data->cpumask); |
419 | |
420 | for_each_cpu(cpu, data->cpumask) { |
421 | struct call_single_data *csd = per_cpu_ptr(data->csd, cpu); |
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 | } |
434 | |
435 | /* Send a message to all CPUs in the map */ |
436 | arch_send_call_function_ipi_mask(data->cpumask_ipi); |
437 | |
438 | if (wait) { |
439 | for_each_cpu(cpu, data->cpumask) { |
440 | struct call_single_data *csd = |
441 | per_cpu_ptr(data->csd, cpu); |
442 | csd_lock_wait(csd); |
443 | } |
444 | } |
445 | } |
446 | EXPORT_SYMBOL(smp_call_function_many); |
447 | |
448 | /** |
449 | * smp_call_function(): Run a function on all other CPUs. |
450 | * @func: The function to run. This must be fast and non-blocking. |
451 | * @info: An arbitrary pointer to pass to the function. |
452 | * @wait: If true, wait (atomically) until function has completed |
453 | * on other CPUs. |
454 | * |
455 | * Returns 0. |
456 | * |
457 | * If @wait is true, then returns once @func has returned; otherwise |
458 | * it returns just before the target cpu calls @func. |
459 | * |
460 | * You must not call this function with disabled interrupts or from a |
461 | * hardware interrupt handler or from a bottom half handler. |
462 | */ |
463 | int smp_call_function(smp_call_func_t func, void *info, int wait) |
464 | { |
465 | preempt_disable(); |
466 | smp_call_function_many(cpu_online_mask, func, info, wait); |
467 | preempt_enable(); |
468 | |
469 | return 0; |
470 | } |
471 | EXPORT_SYMBOL(smp_call_function); |
472 | #endif /* USE_GENERIC_SMP_HELPERS */ |
473 | |
474 | /* Setup configured maximum number of CPUs to activate */ |
475 | unsigned int setup_max_cpus = NR_CPUS; |
476 | EXPORT_SYMBOL(setup_max_cpus); |
477 | |
478 | |
479 | /* |
480 | * Setup routine for controlling SMP activation |
481 | * |
482 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP |
483 | * activation entirely (the MPS table probe still happens, though). |
484 | * |
485 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer |
486 | * greater than 0, limits the maximum number of CPUs activated in |
487 | * SMP mode to <NUM>. |
488 | */ |
489 | |
490 | void __weak arch_disable_smp_support(void) { } |
491 | |
492 | static int __init nosmp(char *str) |
493 | { |
494 | setup_max_cpus = 0; |
495 | arch_disable_smp_support(); |
496 | |
497 | return 0; |
498 | } |
499 | |
500 | early_param("nosmp", nosmp); |
501 | |
502 | /* this is hard limit */ |
503 | static int __init nrcpus(char *str) |
504 | { |
505 | int nr_cpus; |
506 | |
507 | get_option(&str, &nr_cpus); |
508 | if (nr_cpus > 0 && nr_cpus < nr_cpu_ids) |
509 | nr_cpu_ids = nr_cpus; |
510 | |
511 | return 0; |
512 | } |
513 | |
514 | early_param("nr_cpus", nrcpus); |
515 | |
516 | static int __init maxcpus(char *str) |
517 | { |
518 | get_option(&str, &setup_max_cpus); |
519 | if (setup_max_cpus == 0) |
520 | arch_disable_smp_support(); |
521 | |
522 | return 0; |
523 | } |
524 | |
525 | early_param("maxcpus", maxcpus); |
526 | |
527 | /* Setup number of possible processor ids */ |
528 | int nr_cpu_ids __read_mostly = NR_CPUS; |
529 | EXPORT_SYMBOL(nr_cpu_ids); |
530 | |
531 | /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ |
532 | void __init setup_nr_cpu_ids(void) |
533 | { |
534 | nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1; |
535 | } |
536 | |
537 | /* Called by boot processor to activate the rest. */ |
538 | void __init smp_init(void) |
539 | { |
540 | unsigned int cpu; |
541 | |
542 | idle_threads_init(); |
543 | |
544 | /* FIXME: This should be done in userspace --RR */ |
545 | for_each_present_cpu(cpu) { |
546 | if (num_online_cpus() >= setup_max_cpus) |
547 | break; |
548 | if (!cpu_online(cpu)) |
549 | cpu_up(cpu); |
550 | } |
551 | |
552 | /* Any cleanup work */ |
553 | printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus()); |
554 | smp_cpus_done(setup_max_cpus); |
555 | } |
556 | |
557 | /* |
558 | * Call a function on all processors. May be used during early boot while |
559 | * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead |
560 | * of local_irq_disable/enable(). |
561 | */ |
562 | int on_each_cpu(void (*func) (void *info), void *info, int wait) |
563 | { |
564 | unsigned long flags; |
565 | int ret = 0; |
566 | |
567 | preempt_disable(); |
568 | ret = smp_call_function(func, info, wait); |
569 | local_irq_save(flags); |
570 | func(info); |
571 | local_irq_restore(flags); |
572 | preempt_enable(); |
573 | return ret; |
574 | } |
575 | EXPORT_SYMBOL(on_each_cpu); |
576 | |
577 | /** |
578 | * on_each_cpu_mask(): Run a function on processors specified by |
579 | * cpumask, which may include the local processor. |
580 | * @mask: The set of cpus to run on (only runs on online subset). |
581 | * @func: The function to run. This must be fast and non-blocking. |
582 | * @info: An arbitrary pointer to pass to the function. |
583 | * @wait: If true, wait (atomically) until function has completed |
584 | * on other CPUs. |
585 | * |
586 | * If @wait is true, then returns once @func has returned. |
587 | * |
588 | * You must not call this function with disabled interrupts or |
589 | * from a hardware interrupt handler or from a bottom half handler. |
590 | */ |
591 | void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, |
592 | void *info, bool wait) |
593 | { |
594 | int cpu = get_cpu(); |
595 | |
596 | smp_call_function_many(mask, func, info, wait); |
597 | if (cpumask_test_cpu(cpu, mask)) { |
598 | local_irq_disable(); |
599 | func(info); |
600 | local_irq_enable(); |
601 | } |
602 | put_cpu(); |
603 | } |
604 | EXPORT_SYMBOL(on_each_cpu_mask); |
605 | |
606 | /* |
607 | * on_each_cpu_cond(): Call a function on each processor for which |
608 | * the supplied function cond_func returns true, optionally waiting |
609 | * for all the required CPUs to finish. This may include the local |
610 | * processor. |
611 | * @cond_func: A callback function that is passed a cpu id and |
612 | * the the info parameter. The function is called |
613 | * with preemption disabled. The function should |
614 | * return a blooean value indicating whether to IPI |
615 | * the specified CPU. |
616 | * @func: The function to run on all applicable CPUs. |
617 | * This must be fast and non-blocking. |
618 | * @info: An arbitrary pointer to pass to both functions. |
619 | * @wait: If true, wait (atomically) until function has |
620 | * completed on other CPUs. |
621 | * @gfp_flags: GFP flags to use when allocating the cpumask |
622 | * used internally by the function. |
623 | * |
624 | * The function might sleep if the GFP flags indicates a non |
625 | * atomic allocation is allowed. |
626 | * |
627 | * Preemption is disabled to protect against CPUs going offline but not online. |
628 | * CPUs going online during the call will not be seen or sent an IPI. |
629 | * |
630 | * You must not call this function with disabled interrupts or |
631 | * from a hardware interrupt handler or from a bottom half handler. |
632 | */ |
633 | void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), |
634 | smp_call_func_t func, void *info, bool wait, |
635 | gfp_t gfp_flags) |
636 | { |
637 | cpumask_var_t cpus; |
638 | int cpu, ret; |
639 | |
640 | might_sleep_if(gfp_flags & __GFP_WAIT); |
641 | |
642 | if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) { |
643 | preempt_disable(); |
644 | for_each_online_cpu(cpu) |
645 | if (cond_func(cpu, info)) |
646 | cpumask_set_cpu(cpu, cpus); |
647 | on_each_cpu_mask(cpus, func, info, wait); |
648 | preempt_enable(); |
649 | free_cpumask_var(cpus); |
650 | } else { |
651 | /* |
652 | * No free cpumask, bother. No matter, we'll |
653 | * just have to IPI them one by one. |
654 | */ |
655 | preempt_disable(); |
656 | for_each_online_cpu(cpu) |
657 | if (cond_func(cpu, info)) { |
658 | ret = smp_call_function_single(cpu, func, |
659 | info, wait); |
660 | WARN_ON_ONCE(!ret); |
661 | } |
662 | preempt_enable(); |
663 | } |
664 | } |
665 | EXPORT_SYMBOL(on_each_cpu_cond); |
666 | |
667 | static void do_nothing(void *unused) |
668 | { |
669 | } |
670 | |
671 | /** |
672 | * kick_all_cpus_sync - Force all cpus out of idle |
673 | * |
674 | * Used to synchronize the update of pm_idle function pointer. It's |
675 | * called after the pointer is updated and returns after the dummy |
676 | * callback function has been executed on all cpus. The execution of |
677 | * the function can only happen on the remote cpus after they have |
678 | * left the idle function which had been called via pm_idle function |
679 | * pointer. So it's guaranteed that nothing uses the previous pointer |
680 | * anymore. |
681 | */ |
682 | void kick_all_cpus_sync(void) |
683 | { |
684 | /* Make sure the change is visible before we kick the cpus */ |
685 | smp_mb(); |
686 | smp_call_function(do_nothing, NULL, 1); |
687 | } |
688 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync); |
689 |
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v2.6.34-rc5
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