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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Generic helpers for smp ipi calls
4 *
5 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/irq_work.h>
11#include <linux/rcupdate.h>
12#include <linux/rculist.h>
13#include <linux/kernel.h>
14#include <linux/export.h>
15#include <linux/percpu.h>
16#include <linux/init.h>
17#include <linux/gfp.h>
18#include <linux/smp.h>
19#include <linux/cpu.h>
20#include <linux/sched.h>
21#include <linux/sched/idle.h>
22#include <linux/hypervisor.h>
23
24#include "smpboot.h"
25
26enum {
27 CSD_FLAG_LOCK = 0x01,
28 CSD_FLAG_SYNCHRONOUS = 0x02,
29};
30
31struct call_function_data {
32 call_single_data_t __percpu *csd;
33 cpumask_var_t cpumask;
34 cpumask_var_t cpumask_ipi;
35};
36
37static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data);
38
39static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
40
41static void flush_smp_call_function_queue(bool warn_cpu_offline);
42
43int smpcfd_prepare_cpu(unsigned int cpu)
44{
45 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
46
47 if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
48 cpu_to_node(cpu)))
49 return -ENOMEM;
50 if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
51 cpu_to_node(cpu))) {
52 free_cpumask_var(cfd->cpumask);
53 return -ENOMEM;
54 }
55 cfd->csd = alloc_percpu(call_single_data_t);
56 if (!cfd->csd) {
57 free_cpumask_var(cfd->cpumask);
58 free_cpumask_var(cfd->cpumask_ipi);
59 return -ENOMEM;
60 }
61
62 return 0;
63}
64
65int smpcfd_dead_cpu(unsigned int cpu)
66{
67 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
68
69 free_cpumask_var(cfd->cpumask);
70 free_cpumask_var(cfd->cpumask_ipi);
71 free_percpu(cfd->csd);
72 return 0;
73}
74
75int smpcfd_dying_cpu(unsigned int cpu)
76{
77 /*
78 * The IPIs for the smp-call-function callbacks queued by other
79 * CPUs might arrive late, either due to hardware latencies or
80 * because this CPU disabled interrupts (inside stop-machine)
81 * before the IPIs were sent. So flush out any pending callbacks
82 * explicitly (without waiting for the IPIs to arrive), to
83 * ensure that the outgoing CPU doesn't go offline with work
84 * still pending.
85 */
86 flush_smp_call_function_queue(false);
87 return 0;
88}
89
90void __init call_function_init(void)
91{
92 int i;
93
94 for_each_possible_cpu(i)
95 init_llist_head(&per_cpu(call_single_queue, i));
96
97 smpcfd_prepare_cpu(smp_processor_id());
98}
99
100/*
101 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
102 *
103 * For non-synchronous ipi calls the csd can still be in use by the
104 * previous function call. For multi-cpu calls its even more interesting
105 * as we'll have to ensure no other cpu is observing our csd.
106 */
107static __always_inline void csd_lock_wait(call_single_data_t *csd)
108{
109 smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
110}
111
112static __always_inline void csd_lock(call_single_data_t *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_t structure:
121 */
122 smp_wmb();
123}
124
125static __always_inline void csd_unlock(call_single_data_t *csd)
126{
127 WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
128
129 /*
130 * ensure we're all done before releasing data:
131 */
132 smp_store_release(&csd->flags, 0);
133}
134
135static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
136
137/*
138 * Insert a previously allocated call_single_data_t element
139 * for execution on the given CPU. data must already have
140 * ->func, ->info, and ->flags set.
141 */
142static int generic_exec_single(int cpu, call_single_data_t *csd,
143 smp_call_func_t func, void *info)
144{
145 if (cpu == smp_processor_id()) {
146 unsigned long flags;
147
148 /*
149 * We can unlock early even for the synchronous on-stack case,
150 * since we're doing this from the same CPU..
151 */
152 csd_unlock(csd);
153 local_irq_save(flags);
154 func(info);
155 local_irq_restore(flags);
156 return 0;
157 }
158
159
160 if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
161 csd_unlock(csd);
162 return -ENXIO;
163 }
164
165 csd->func = func;
166 csd->info = info;
167
168 /*
169 * The list addition should be visible before sending the IPI
170 * handler locks the list to pull the entry off it because of
171 * normal cache coherency rules implied by spinlocks.
172 *
173 * If IPIs can go out of order to the cache coherency protocol
174 * in an architecture, sufficient synchronisation should be added
175 * to arch code to make it appear to obey cache coherency WRT
176 * locking and barrier primitives. Generic code isn't really
177 * equipped to do the right thing...
178 */
179 if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
180 arch_send_call_function_single_ipi(cpu);
181
182 return 0;
183}
184
185/**
186 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
187 *
188 * Invoked by arch to handle an IPI for call function single.
189 * Must be called with interrupts disabled.
190 */
191void generic_smp_call_function_single_interrupt(void)
192{
193 flush_smp_call_function_queue(true);
194}
195
196/**
197 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
198 *
199 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
200 * offline CPU. Skip this check if set to 'false'.
201 *
202 * Flush any pending smp-call-function callbacks queued on this CPU. This is
203 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
204 * to ensure that all pending IPI callbacks are run before it goes completely
205 * offline.
206 *
207 * Loop through the call_single_queue and run all the queued callbacks.
208 * Must be called with interrupts disabled.
209 */
210static void flush_smp_call_function_queue(bool warn_cpu_offline)
211{
212 struct llist_head *head;
213 struct llist_node *entry;
214 call_single_data_t *csd, *csd_next;
215 static bool warned;
216
217 lockdep_assert_irqs_disabled();
218
219 head = this_cpu_ptr(&call_single_queue);
220 entry = llist_del_all(head);
221 entry = llist_reverse_order(entry);
222
223 /* There shouldn't be any pending callbacks on an offline CPU. */
224 if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
225 !warned && !llist_empty(head))) {
226 warned = true;
227 WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
228
229 /*
230 * We don't have to use the _safe() variant here
231 * because we are not invoking the IPI handlers yet.
232 */
233 llist_for_each_entry(csd, entry, llist)
234 pr_warn("IPI callback %pS sent to offline CPU\n",
235 csd->func);
236 }
237
238 llist_for_each_entry_safe(csd, csd_next, entry, llist) {
239 smp_call_func_t func = csd->func;
240 void *info = csd->info;
241
242 /* Do we wait until *after* callback? */
243 if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
244 func(info);
245 csd_unlock(csd);
246 } else {
247 csd_unlock(csd);
248 func(info);
249 }
250 }
251
252 /*
253 * Handle irq works queued remotely by irq_work_queue_on().
254 * Smp functions above are typically synchronous so they
255 * better run first since some other CPUs may be busy waiting
256 * for them.
257 */
258 irq_work_run();
259}
260
261/*
262 * smp_call_function_single - Run a function on a specific CPU
263 * @func: The function to run. This must be fast and non-blocking.
264 * @info: An arbitrary pointer to pass to the function.
265 * @wait: If true, wait until function has completed on other CPUs.
266 *
267 * Returns 0 on success, else a negative status code.
268 */
269int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
270 int wait)
271{
272 call_single_data_t *csd;
273 call_single_data_t csd_stack = {
274 .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS,
275 };
276 int this_cpu;
277 int err;
278
279 /*
280 * prevent preemption and reschedule on another processor,
281 * as well as CPU removal
282 */
283 this_cpu = get_cpu();
284
285 /*
286 * Can deadlock when called with interrupts disabled.
287 * We allow cpu's that are not yet online though, as no one else can
288 * send smp call function interrupt to this cpu and as such deadlocks
289 * can't happen.
290 */
291 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
292 && !oops_in_progress);
293
294 /*
295 * When @wait we can deadlock when we interrupt between llist_add() and
296 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
297 * csd_lock() on because the interrupt context uses the same csd
298 * storage.
299 */
300 WARN_ON_ONCE(!in_task());
301
302 csd = &csd_stack;
303 if (!wait) {
304 csd = this_cpu_ptr(&csd_data);
305 csd_lock(csd);
306 }
307
308 err = generic_exec_single(cpu, csd, func, info);
309
310 if (wait)
311 csd_lock_wait(csd);
312
313 put_cpu();
314
315 return err;
316}
317EXPORT_SYMBOL(smp_call_function_single);
318
319/**
320 * smp_call_function_single_async(): Run an asynchronous function on a
321 * specific CPU.
322 * @cpu: The CPU to run on.
323 * @csd: Pre-allocated and setup data structure
324 *
325 * Like smp_call_function_single(), but the call is asynchonous and
326 * can thus be done from contexts with disabled interrupts.
327 *
328 * The caller passes his own pre-allocated data structure
329 * (ie: embedded in an object) and is responsible for synchronizing it
330 * such that the IPIs performed on the @csd are strictly serialized.
331 *
332 * NOTE: Be careful, there is unfortunately no current debugging facility to
333 * validate the correctness of this serialization.
334 */
335int smp_call_function_single_async(int cpu, call_single_data_t *csd)
336{
337 int err = 0;
338
339 preempt_disable();
340
341 /* We could deadlock if we have to wait here with interrupts disabled! */
342 if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
343 csd_lock_wait(csd);
344
345 csd->flags = CSD_FLAG_LOCK;
346 smp_wmb();
347
348 err = generic_exec_single(cpu, csd, csd->func, csd->info);
349 preempt_enable();
350
351 return err;
352}
353EXPORT_SYMBOL_GPL(smp_call_function_single_async);
354
355/*
356 * smp_call_function_any - Run a function on any of the given cpus
357 * @mask: The mask of cpus it can run on.
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 until function has completed.
361 *
362 * Returns 0 on success, else a negative status code (if no cpus were online).
363 *
364 * Selection preference:
365 * 1) current cpu if in @mask
366 * 2) any cpu of current node if in @mask
367 * 3) any other online cpu in @mask
368 */
369int smp_call_function_any(const struct cpumask *mask,
370 smp_call_func_t func, void *info, int wait)
371{
372 unsigned int cpu;
373 const struct cpumask *nodemask;
374 int ret;
375
376 /* Try for same CPU (cheapest) */
377 cpu = get_cpu();
378 if (cpumask_test_cpu(cpu, mask))
379 goto call;
380
381 /* Try for same node. */
382 nodemask = cpumask_of_node(cpu_to_node(cpu));
383 for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
384 cpu = cpumask_next_and(cpu, nodemask, mask)) {
385 if (cpu_online(cpu))
386 goto call;
387 }
388
389 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
390 cpu = cpumask_any_and(mask, cpu_online_mask);
391call:
392 ret = smp_call_function_single(cpu, func, info, wait);
393 put_cpu();
394 return ret;
395}
396EXPORT_SYMBOL_GPL(smp_call_function_any);
397
398/**
399 * smp_call_function_many(): Run a function on a set of other CPUs.
400 * @mask: The set of cpus to run on (only runs on online subset).
401 * @func: The function to run. This must be fast and non-blocking.
402 * @info: An arbitrary pointer to pass to the function.
403 * @wait: If true, wait (atomically) until function has completed
404 * on other CPUs.
405 *
406 * If @wait is true, then returns once @func has returned.
407 *
408 * You must not call this function with disabled interrupts or from a
409 * hardware interrupt handler or from a bottom half handler. Preemption
410 * must be disabled when calling this function.
411 */
412void smp_call_function_many(const struct cpumask *mask,
413 smp_call_func_t func, void *info, bool wait)
414{
415 struct call_function_data *cfd;
416 int cpu, next_cpu, this_cpu = smp_processor_id();
417
418 /*
419 * Can deadlock when called with interrupts disabled.
420 * We allow cpu's that are not yet online though, as no one else can
421 * send smp call function interrupt to this cpu and as such deadlocks
422 * can't happen.
423 */
424 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
425 && !oops_in_progress && !early_boot_irqs_disabled);
426
427 /*
428 * When @wait we can deadlock when we interrupt between llist_add() and
429 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
430 * csd_lock() on because the interrupt context uses the same csd
431 * storage.
432 */
433 WARN_ON_ONCE(!in_task());
434
435 /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
436 cpu = cpumask_first_and(mask, cpu_online_mask);
437 if (cpu == this_cpu)
438 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
439
440 /* No online cpus? We're done. */
441 if (cpu >= nr_cpu_ids)
442 return;
443
444 /* Do we have another CPU which isn't us? */
445 next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
446 if (next_cpu == this_cpu)
447 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
448
449 /* Fastpath: do that cpu by itself. */
450 if (next_cpu >= nr_cpu_ids) {
451 smp_call_function_single(cpu, func, info, wait);
452 return;
453 }
454
455 cfd = this_cpu_ptr(&cfd_data);
456
457 cpumask_and(cfd->cpumask, mask, cpu_online_mask);
458 __cpumask_clear_cpu(this_cpu, cfd->cpumask);
459
460 /* Some callers race with other cpus changing the passed mask */
461 if (unlikely(!cpumask_weight(cfd->cpumask)))
462 return;
463
464 cpumask_clear(cfd->cpumask_ipi);
465 for_each_cpu(cpu, cfd->cpumask) {
466 call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
467
468 csd_lock(csd);
469 if (wait)
470 csd->flags |= CSD_FLAG_SYNCHRONOUS;
471 csd->func = func;
472 csd->info = info;
473 if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
474 __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
475 }
476
477 /* Send a message to all CPUs in the map */
478 arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
479
480 if (wait) {
481 for_each_cpu(cpu, cfd->cpumask) {
482 call_single_data_t *csd;
483
484 csd = per_cpu_ptr(cfd->csd, cpu);
485 csd_lock_wait(csd);
486 }
487 }
488}
489EXPORT_SYMBOL(smp_call_function_many);
490
491/**
492 * smp_call_function(): Run a function on all other CPUs.
493 * @func: The function to run. This must be fast and non-blocking.
494 * @info: An arbitrary pointer to pass to the function.
495 * @wait: If true, wait (atomically) until function has completed
496 * on other CPUs.
497 *
498 * Returns 0.
499 *
500 * If @wait is true, then returns once @func has returned; otherwise
501 * it returns just before the target cpu calls @func.
502 *
503 * You must not call this function with disabled interrupts or from a
504 * hardware interrupt handler or from a bottom half handler.
505 */
506void smp_call_function(smp_call_func_t func, void *info, int wait)
507{
508 preempt_disable();
509 smp_call_function_many(cpu_online_mask, func, info, wait);
510 preempt_enable();
511}
512EXPORT_SYMBOL(smp_call_function);
513
514/* Setup configured maximum number of CPUs to activate */
515unsigned int setup_max_cpus = NR_CPUS;
516EXPORT_SYMBOL(setup_max_cpus);
517
518
519/*
520 * Setup routine for controlling SMP activation
521 *
522 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
523 * activation entirely (the MPS table probe still happens, though).
524 *
525 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
526 * greater than 0, limits the maximum number of CPUs activated in
527 * SMP mode to <NUM>.
528 */
529
530void __weak arch_disable_smp_support(void) { }
531
532static int __init nosmp(char *str)
533{
534 setup_max_cpus = 0;
535 arch_disable_smp_support();
536
537 return 0;
538}
539
540early_param("nosmp", nosmp);
541
542/* this is hard limit */
543static int __init nrcpus(char *str)
544{
545 int nr_cpus;
546
547 get_option(&str, &nr_cpus);
548 if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
549 nr_cpu_ids = nr_cpus;
550
551 return 0;
552}
553
554early_param("nr_cpus", nrcpus);
555
556static int __init maxcpus(char *str)
557{
558 get_option(&str, &setup_max_cpus);
559 if (setup_max_cpus == 0)
560 arch_disable_smp_support();
561
562 return 0;
563}
564
565early_param("maxcpus", maxcpus);
566
567/* Setup number of possible processor ids */
568unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
569EXPORT_SYMBOL(nr_cpu_ids);
570
571/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
572void __init setup_nr_cpu_ids(void)
573{
574 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
575}
576
577/* Called by boot processor to activate the rest. */
578void __init smp_init(void)
579{
580 int num_nodes, num_cpus;
581 unsigned int cpu;
582
583 idle_threads_init();
584 cpuhp_threads_init();
585
586 pr_info("Bringing up secondary CPUs ...\n");
587
588 /* FIXME: This should be done in userspace --RR */
589 for_each_present_cpu(cpu) {
590 if (num_online_cpus() >= setup_max_cpus)
591 break;
592 if (!cpu_online(cpu))
593 cpu_up(cpu);
594 }
595
596 num_nodes = num_online_nodes();
597 num_cpus = num_online_cpus();
598 pr_info("Brought up %d node%s, %d CPU%s\n",
599 num_nodes, (num_nodes > 1 ? "s" : ""),
600 num_cpus, (num_cpus > 1 ? "s" : ""));
601
602 /* Any cleanup work */
603 smp_cpus_done(setup_max_cpus);
604}
605
606/*
607 * Call a function on all processors. May be used during early boot while
608 * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
609 * of local_irq_disable/enable().
610 */
611void on_each_cpu(void (*func) (void *info), void *info, int wait)
612{
613 unsigned long flags;
614
615 preempt_disable();
616 smp_call_function(func, info, wait);
617 local_irq_save(flags);
618 func(info);
619 local_irq_restore(flags);
620 preempt_enable();
621}
622EXPORT_SYMBOL(on_each_cpu);
623
624/**
625 * on_each_cpu_mask(): Run a function on processors specified by
626 * cpumask, which may include the local processor.
627 * @mask: The set of cpus to run on (only runs on online subset).
628 * @func: The function to run. This must be fast and non-blocking.
629 * @info: An arbitrary pointer to pass to the function.
630 * @wait: If true, wait (atomically) until function has completed
631 * on other CPUs.
632 *
633 * If @wait is true, then returns once @func has returned.
634 *
635 * You must not call this function with disabled interrupts or from a
636 * hardware interrupt handler or from a bottom half handler. The
637 * exception is that it may be used during early boot while
638 * early_boot_irqs_disabled is set.
639 */
640void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
641 void *info, bool wait)
642{
643 int cpu = get_cpu();
644
645 smp_call_function_many(mask, func, info, wait);
646 if (cpumask_test_cpu(cpu, mask)) {
647 unsigned long flags;
648 local_irq_save(flags);
649 func(info);
650 local_irq_restore(flags);
651 }
652 put_cpu();
653}
654EXPORT_SYMBOL(on_each_cpu_mask);
655
656/*
657 * on_each_cpu_cond(): Call a function on each processor for which
658 * the supplied function cond_func returns true, optionally waiting
659 * for all the required CPUs to finish. This may include the local
660 * processor.
661 * @cond_func: A callback function that is passed a cpu id and
662 * the the info parameter. The function is called
663 * with preemption disabled. The function should
664 * return a blooean value indicating whether to IPI
665 * the specified CPU.
666 * @func: The function to run on all applicable CPUs.
667 * This must be fast and non-blocking.
668 * @info: An arbitrary pointer to pass to both functions.
669 * @wait: If true, wait (atomically) until function has
670 * completed on other CPUs.
671 * @gfp_flags: GFP flags to use when allocating the cpumask
672 * used internally by the function.
673 *
674 * The function might sleep if the GFP flags indicates a non
675 * atomic allocation is allowed.
676 *
677 * Preemption is disabled to protect against CPUs going offline but not online.
678 * CPUs going online during the call will not be seen or sent an IPI.
679 *
680 * You must not call this function with disabled interrupts or
681 * from a hardware interrupt handler or from a bottom half handler.
682 */
683void on_each_cpu_cond_mask(bool (*cond_func)(int cpu, void *info),
684 smp_call_func_t func, void *info, bool wait,
685 gfp_t gfp_flags, const struct cpumask *mask)
686{
687 cpumask_var_t cpus;
688 int cpu, ret;
689
690 might_sleep_if(gfpflags_allow_blocking(gfp_flags));
691
692 if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
693 preempt_disable();
694 for_each_cpu(cpu, mask)
695 if (cond_func(cpu, info))
696 __cpumask_set_cpu(cpu, cpus);
697 on_each_cpu_mask(cpus, func, info, wait);
698 preempt_enable();
699 free_cpumask_var(cpus);
700 } else {
701 /*
702 * No free cpumask, bother. No matter, we'll
703 * just have to IPI them one by one.
704 */
705 preempt_disable();
706 for_each_cpu(cpu, mask)
707 if (cond_func(cpu, info)) {
708 ret = smp_call_function_single(cpu, func,
709 info, wait);
710 WARN_ON_ONCE(ret);
711 }
712 preempt_enable();
713 }
714}
715EXPORT_SYMBOL(on_each_cpu_cond_mask);
716
717void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
718 smp_call_func_t func, void *info, bool wait,
719 gfp_t gfp_flags)
720{
721 on_each_cpu_cond_mask(cond_func, func, info, wait, gfp_flags,
722 cpu_online_mask);
723}
724EXPORT_SYMBOL(on_each_cpu_cond);
725
726static void do_nothing(void *unused)
727{
728}
729
730/**
731 * kick_all_cpus_sync - Force all cpus out of idle
732 *
733 * Used to synchronize the update of pm_idle function pointer. It's
734 * called after the pointer is updated and returns after the dummy
735 * callback function has been executed on all cpus. The execution of
736 * the function can only happen on the remote cpus after they have
737 * left the idle function which had been called via pm_idle function
738 * pointer. So it's guaranteed that nothing uses the previous pointer
739 * anymore.
740 */
741void kick_all_cpus_sync(void)
742{
743 /* Make sure the change is visible before we kick the cpus */
744 smp_mb();
745 smp_call_function(do_nothing, NULL, 1);
746}
747EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
748
749/**
750 * wake_up_all_idle_cpus - break all cpus out of idle
751 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
752 * including idle polling cpus, for non-idle cpus, we will do nothing
753 * for them.
754 */
755void wake_up_all_idle_cpus(void)
756{
757 int cpu;
758
759 preempt_disable();
760 for_each_online_cpu(cpu) {
761 if (cpu == smp_processor_id())
762 continue;
763
764 wake_up_if_idle(cpu);
765 }
766 preempt_enable();
767}
768EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
769
770/**
771 * smp_call_on_cpu - Call a function on a specific cpu
772 *
773 * Used to call a function on a specific cpu and wait for it to return.
774 * Optionally make sure the call is done on a specified physical cpu via vcpu
775 * pinning in order to support virtualized environments.
776 */
777struct smp_call_on_cpu_struct {
778 struct work_struct work;
779 struct completion done;
780 int (*func)(void *);
781 void *data;
782 int ret;
783 int cpu;
784};
785
786static void smp_call_on_cpu_callback(struct work_struct *work)
787{
788 struct smp_call_on_cpu_struct *sscs;
789
790 sscs = container_of(work, struct smp_call_on_cpu_struct, work);
791 if (sscs->cpu >= 0)
792 hypervisor_pin_vcpu(sscs->cpu);
793 sscs->ret = sscs->func(sscs->data);
794 if (sscs->cpu >= 0)
795 hypervisor_pin_vcpu(-1);
796
797 complete(&sscs->done);
798}
799
800int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
801{
802 struct smp_call_on_cpu_struct sscs = {
803 .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
804 .func = func,
805 .data = par,
806 .cpu = phys ? cpu : -1,
807 };
808
809 INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
810
811 if (cpu >= nr_cpu_ids || !cpu_online(cpu))
812 return -ENXIO;
813
814 queue_work_on(cpu, system_wq, &sscs.work);
815 wait_for_completion(&sscs.done);
816
817 return sscs.ret;
818}
819EXPORT_SYMBOL_GPL(smp_call_on_cpu);
1/*
2 * Generic helpers for smp ipi calls
3 *
4 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
5 */
6#include <linux/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);