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