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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 <[email protected]> 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/interrupt.h>
18#include <linux/gfp.h>
19#include <linux/smp.h>
20#include <linux/cpu.h>
21#include <linux/sched.h>
22#include <linux/sched/idle.h>
23#include <linux/hypervisor.h>
24#include <linux/sched/clock.h>
25#include <linux/nmi.h>
26#include <linux/sched/debug.h>
27#include <linux/jump_label.h>
28
29#include <trace/events/ipi.h>
30#define CREATE_TRACE_POINTS
31#include <trace/events/csd.h>
32#undef CREATE_TRACE_POINTS
33
34#include "smpboot.h"
35#include "sched/smp.h"
36
37#define CSD_TYPE(_csd) ((_csd)->node.u_flags & CSD_FLAG_TYPE_MASK)
38
39struct call_function_data {
40 call_single_data_t __percpu *csd;
41 cpumask_var_t cpumask;
42 cpumask_var_t cpumask_ipi;
43};
44
45static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data);
46
47static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
48
49static void __flush_smp_call_function_queue(bool warn_cpu_offline);
50
51int smpcfd_prepare_cpu(unsigned int cpu)
52{
53 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
54
55 if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
56 cpu_to_node(cpu)))
57 return -ENOMEM;
58 if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
59 cpu_to_node(cpu))) {
60 free_cpumask_var(cfd->cpumask);
61 return -ENOMEM;
62 }
63 cfd->csd = alloc_percpu(call_single_data_t);
64 if (!cfd->csd) {
65 free_cpumask_var(cfd->cpumask);
66 free_cpumask_var(cfd->cpumask_ipi);
67 return -ENOMEM;
68 }
69
70 return 0;
71}
72
73int smpcfd_dead_cpu(unsigned int cpu)
74{
75 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
76
77 free_cpumask_var(cfd->cpumask);
78 free_cpumask_var(cfd->cpumask_ipi);
79 free_percpu(cfd->csd);
80 return 0;
81}
82
83int smpcfd_dying_cpu(unsigned int cpu)
84{
85 /*
86 * The IPIs for the smp-call-function callbacks queued by other
87 * CPUs might arrive late, either due to hardware latencies or
88 * because this CPU disabled interrupts (inside stop-machine)
89 * before the IPIs were sent. So flush out any pending callbacks
90 * explicitly (without waiting for the IPIs to arrive), to
91 * ensure that the outgoing CPU doesn't go offline with work
92 * still pending.
93 */
94 __flush_smp_call_function_queue(false);
95 irq_work_run();
96 return 0;
97}
98
99void __init call_function_init(void)
100{
101 int i;
102
103 for_each_possible_cpu(i)
104 init_llist_head(&per_cpu(call_single_queue, i));
105
106 smpcfd_prepare_cpu(smp_processor_id());
107}
108
109static __always_inline void
110send_call_function_single_ipi(int cpu)
111{
112 if (call_function_single_prep_ipi(cpu)) {
113 trace_ipi_send_cpu(cpu, _RET_IP_,
114 generic_smp_call_function_single_interrupt);
115 arch_send_call_function_single_ipi(cpu);
116 }
117}
118
119static __always_inline void
120send_call_function_ipi_mask(struct cpumask *mask)
121{
122 trace_ipi_send_cpumask(mask, _RET_IP_,
123 generic_smp_call_function_single_interrupt);
124 arch_send_call_function_ipi_mask(mask);
125}
126
127static __always_inline void
128csd_do_func(smp_call_func_t func, void *info, struct __call_single_data *csd)
129{
130 trace_csd_function_entry(func, csd);
131 func(info);
132 trace_csd_function_exit(func, csd);
133}
134
135#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
136
137static DEFINE_STATIC_KEY_MAYBE(CONFIG_CSD_LOCK_WAIT_DEBUG_DEFAULT, csdlock_debug_enabled);
138
139/*
140 * Parse the csdlock_debug= kernel boot parameter.
141 *
142 * If you need to restore the old "ext" value that once provided
143 * additional debugging information, reapply the following commits:
144 *
145 * de7b09ef658d ("locking/csd_lock: Prepare more CSD lock debugging")
146 * a5aabace5fb8 ("locking/csd_lock: Add more data to CSD lock debugging")
147 */
148static int __init csdlock_debug(char *str)
149{
150 int ret;
151 unsigned int val = 0;
152
153 ret = get_option(&str, &val);
154 if (ret) {
155 if (val)
156 static_branch_enable(&csdlock_debug_enabled);
157 else
158 static_branch_disable(&csdlock_debug_enabled);
159 }
160
161 return 1;
162}
163__setup("csdlock_debug=", csdlock_debug);
164
165static DEFINE_PER_CPU(call_single_data_t *, cur_csd);
166static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);
167static DEFINE_PER_CPU(void *, cur_csd_info);
168
169static ulong csd_lock_timeout = 5000; /* CSD lock timeout in milliseconds. */
170module_param(csd_lock_timeout, ulong, 0444);
171
172static atomic_t csd_bug_count = ATOMIC_INIT(0);
173
174/* Record current CSD work for current CPU, NULL to erase. */
175static void __csd_lock_record(struct __call_single_data *csd)
176{
177 if (!csd) {
178 smp_mb(); /* NULL cur_csd after unlock. */
179 __this_cpu_write(cur_csd, NULL);
180 return;
181 }
182 __this_cpu_write(cur_csd_func, csd->func);
183 __this_cpu_write(cur_csd_info, csd->info);
184 smp_wmb(); /* func and info before csd. */
185 __this_cpu_write(cur_csd, csd);
186 smp_mb(); /* Update cur_csd before function call. */
187 /* Or before unlock, as the case may be. */
188}
189
190static __always_inline void csd_lock_record(struct __call_single_data *csd)
191{
192 if (static_branch_unlikely(&csdlock_debug_enabled))
193 __csd_lock_record(csd);
194}
195
196static int csd_lock_wait_getcpu(struct __call_single_data *csd)
197{
198 unsigned int csd_type;
199
200 csd_type = CSD_TYPE(csd);
201 if (csd_type == CSD_TYPE_ASYNC || csd_type == CSD_TYPE_SYNC)
202 return csd->node.dst; /* Other CSD_TYPE_ values might not have ->dst. */
203 return -1;
204}
205
206/*
207 * Complain if too much time spent waiting. Note that only
208 * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
209 * so waiting on other types gets much less information.
210 */
211static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 *ts1, int *bug_id)
212{
213 int cpu = -1;
214 int cpux;
215 bool firsttime;
216 u64 ts2, ts_delta;
217 call_single_data_t *cpu_cur_csd;
218 unsigned int flags = READ_ONCE(csd->node.u_flags);
219 unsigned long long csd_lock_timeout_ns = csd_lock_timeout * NSEC_PER_MSEC;
220
221 if (!(flags & CSD_FLAG_LOCK)) {
222 if (!unlikely(*bug_id))
223 return true;
224 cpu = csd_lock_wait_getcpu(csd);
225 pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
226 *bug_id, raw_smp_processor_id(), cpu);
227 return true;
228 }
229
230 ts2 = sched_clock();
231 ts_delta = ts2 - *ts1;
232 if (likely(ts_delta <= csd_lock_timeout_ns || csd_lock_timeout_ns == 0))
233 return false;
234
235 firsttime = !*bug_id;
236 if (firsttime)
237 *bug_id = atomic_inc_return(&csd_bug_count);
238 cpu = csd_lock_wait_getcpu(csd);
239 if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu))
240 cpux = 0;
241 else
242 cpux = cpu;
243 cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */
244 pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %llu ns for CPU#%02d %pS(%ps).\n",
245 firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), ts2 - ts0,
246 cpu, csd->func, csd->info);
247 if (cpu_cur_csd && csd != cpu_cur_csd) {
248 pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
249 *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)),
250 READ_ONCE(per_cpu(cur_csd_info, cpux)));
251 } else {
252 pr_alert("\tcsd: CSD lock (#%d) %s.\n",
253 *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
254 }
255 if (cpu >= 0) {
256 dump_cpu_task(cpu);
257 if (!cpu_cur_csd) {
258 pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
259 arch_send_call_function_single_ipi(cpu);
260 }
261 }
262 dump_stack();
263 *ts1 = ts2;
264
265 return false;
266}
267
268/*
269 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
270 *
271 * For non-synchronous ipi calls the csd can still be in use by the
272 * previous function call. For multi-cpu calls its even more interesting
273 * as we'll have to ensure no other cpu is observing our csd.
274 */
275static void __csd_lock_wait(struct __call_single_data *csd)
276{
277 int bug_id = 0;
278 u64 ts0, ts1;
279
280 ts1 = ts0 = sched_clock();
281 for (;;) {
282 if (csd_lock_wait_toolong(csd, ts0, &ts1, &bug_id))
283 break;
284 cpu_relax();
285 }
286 smp_acquire__after_ctrl_dep();
287}
288
289static __always_inline void csd_lock_wait(struct __call_single_data *csd)
290{
291 if (static_branch_unlikely(&csdlock_debug_enabled)) {
292 __csd_lock_wait(csd);
293 return;
294 }
295
296 smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
297}
298#else
299static void csd_lock_record(struct __call_single_data *csd)
300{
301}
302
303static __always_inline void csd_lock_wait(struct __call_single_data *csd)
304{
305 smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
306}
307#endif
308
309static __always_inline void csd_lock(struct __call_single_data *csd)
310{
311 csd_lock_wait(csd);
312 csd->node.u_flags |= CSD_FLAG_LOCK;
313
314 /*
315 * prevent CPU from reordering the above assignment
316 * to ->flags with any subsequent assignments to other
317 * fields of the specified call_single_data_t structure:
318 */
319 smp_wmb();
320}
321
322static __always_inline void csd_unlock(struct __call_single_data *csd)
323{
324 WARN_ON(!(csd->node.u_flags & CSD_FLAG_LOCK));
325
326 /*
327 * ensure we're all done before releasing data:
328 */
329 smp_store_release(&csd->node.u_flags, 0);
330}
331
332static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
333
334void __smp_call_single_queue(int cpu, struct llist_node *node)
335{
336 /*
337 * We have to check the type of the CSD before queueing it, because
338 * once queued it can have its flags cleared by
339 * flush_smp_call_function_queue()
340 * even if we haven't sent the smp_call IPI yet (e.g. the stopper
341 * executes migration_cpu_stop() on the remote CPU).
342 */
343 if (trace_csd_queue_cpu_enabled()) {
344 call_single_data_t *csd;
345 smp_call_func_t func;
346
347 csd = container_of(node, call_single_data_t, node.llist);
348 func = CSD_TYPE(csd) == CSD_TYPE_TTWU ?
349 sched_ttwu_pending : csd->func;
350
351 trace_csd_queue_cpu(cpu, _RET_IP_, func, csd);
352 }
353
354 /*
355 * The list addition should be visible to the target CPU when it pops
356 * the head of the list to pull the entry off it in the IPI handler
357 * because of normal cache coherency rules implied by the underlying
358 * llist ops.
359 *
360 * If IPIs can go out of order to the cache coherency protocol
361 * in an architecture, sufficient synchronisation should be added
362 * to arch code to make it appear to obey cache coherency WRT
363 * locking and barrier primitives. Generic code isn't really
364 * equipped to do the right thing...
365 */
366 if (llist_add(node, &per_cpu(call_single_queue, cpu)))
367 send_call_function_single_ipi(cpu);
368}
369
370/*
371 * Insert a previously allocated call_single_data_t element
372 * for execution on the given CPU. data must already have
373 * ->func, ->info, and ->flags set.
374 */
375static int generic_exec_single(int cpu, struct __call_single_data *csd)
376{
377 if (cpu == smp_processor_id()) {
378 smp_call_func_t func = csd->func;
379 void *info = csd->info;
380 unsigned long flags;
381
382 /*
383 * We can unlock early even for the synchronous on-stack case,
384 * since we're doing this from the same CPU..
385 */
386 csd_lock_record(csd);
387 csd_unlock(csd);
388 local_irq_save(flags);
389 csd_do_func(func, info, NULL);
390 csd_lock_record(NULL);
391 local_irq_restore(flags);
392 return 0;
393 }
394
395 if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
396 csd_unlock(csd);
397 return -ENXIO;
398 }
399
400 __smp_call_single_queue(cpu, &csd->node.llist);
401
402 return 0;
403}
404
405/**
406 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
407 *
408 * Invoked by arch to handle an IPI for call function single.
409 * Must be called with interrupts disabled.
410 */
411void generic_smp_call_function_single_interrupt(void)
412{
413 __flush_smp_call_function_queue(true);
414}
415
416/**
417 * __flush_smp_call_function_queue - Flush pending smp-call-function callbacks
418 *
419 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
420 * offline CPU. Skip this check if set to 'false'.
421 *
422 * Flush any pending smp-call-function callbacks queued on this CPU. This is
423 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
424 * to ensure that all pending IPI callbacks are run before it goes completely
425 * offline.
426 *
427 * Loop through the call_single_queue and run all the queued callbacks.
428 * Must be called with interrupts disabled.
429 */
430static void __flush_smp_call_function_queue(bool warn_cpu_offline)
431{
432 call_single_data_t *csd, *csd_next;
433 struct llist_node *entry, *prev;
434 struct llist_head *head;
435 static bool warned;
436
437 lockdep_assert_irqs_disabled();
438
439 head = this_cpu_ptr(&call_single_queue);
440 entry = llist_del_all(head);
441 entry = llist_reverse_order(entry);
442
443 /* There shouldn't be any pending callbacks on an offline CPU. */
444 if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
445 !warned && entry != NULL)) {
446 warned = true;
447 WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
448
449 /*
450 * We don't have to use the _safe() variant here
451 * because we are not invoking the IPI handlers yet.
452 */
453 llist_for_each_entry(csd, entry, node.llist) {
454 switch (CSD_TYPE(csd)) {
455 case CSD_TYPE_ASYNC:
456 case CSD_TYPE_SYNC:
457 case CSD_TYPE_IRQ_WORK:
458 pr_warn("IPI callback %pS sent to offline CPU\n",
459 csd->func);
460 break;
461
462 case CSD_TYPE_TTWU:
463 pr_warn("IPI task-wakeup sent to offline CPU\n");
464 break;
465
466 default:
467 pr_warn("IPI callback, unknown type %d, sent to offline CPU\n",
468 CSD_TYPE(csd));
469 break;
470 }
471 }
472 }
473
474 /*
475 * First; run all SYNC callbacks, people are waiting for us.
476 */
477 prev = NULL;
478 llist_for_each_entry_safe(csd, csd_next, entry, node.llist) {
479 /* Do we wait until *after* callback? */
480 if (CSD_TYPE(csd) == CSD_TYPE_SYNC) {
481 smp_call_func_t func = csd->func;
482 void *info = csd->info;
483
484 if (prev) {
485 prev->next = &csd_next->node.llist;
486 } else {
487 entry = &csd_next->node.llist;
488 }
489
490 csd_lock_record(csd);
491 csd_do_func(func, info, csd);
492 csd_unlock(csd);
493 csd_lock_record(NULL);
494 } else {
495 prev = &csd->node.llist;
496 }
497 }
498
499 if (!entry)
500 return;
501
502 /*
503 * Second; run all !SYNC callbacks.
504 */
505 prev = NULL;
506 llist_for_each_entry_safe(csd, csd_next, entry, node.llist) {
507 int type = CSD_TYPE(csd);
508
509 if (type != CSD_TYPE_TTWU) {
510 if (prev) {
511 prev->next = &csd_next->node.llist;
512 } else {
513 entry = &csd_next->node.llist;
514 }
515
516 if (type == CSD_TYPE_ASYNC) {
517 smp_call_func_t func = csd->func;
518 void *info = csd->info;
519
520 csd_lock_record(csd);
521 csd_unlock(csd);
522 csd_do_func(func, info, csd);
523 csd_lock_record(NULL);
524 } else if (type == CSD_TYPE_IRQ_WORK) {
525 irq_work_single(csd);
526 }
527
528 } else {
529 prev = &csd->node.llist;
530 }
531 }
532
533 /*
534 * Third; only CSD_TYPE_TTWU is left, issue those.
535 */
536 if (entry) {
537 csd = llist_entry(entry, typeof(*csd), node.llist);
538 csd_do_func(sched_ttwu_pending, entry, csd);
539 }
540}
541
542
543/**
544 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
545 * from task context (idle, migration thread)
546 *
547 * When TIF_POLLING_NRFLAG is supported and a CPU is in idle and has it
548 * set, then remote CPUs can avoid sending IPIs and wake the idle CPU by
549 * setting TIF_NEED_RESCHED. The idle task on the woken up CPU has to
550 * handle queued SMP function calls before scheduling.
551 *
552 * The migration thread has to ensure that an eventually pending wakeup has
553 * been handled before it migrates a task.
554 */
555void flush_smp_call_function_queue(void)
556{
557 unsigned int was_pending;
558 unsigned long flags;
559
560 if (llist_empty(this_cpu_ptr(&call_single_queue)))
561 return;
562
563 local_irq_save(flags);
564 /* Get the already pending soft interrupts for RT enabled kernels */
565 was_pending = local_softirq_pending();
566 __flush_smp_call_function_queue(true);
567 if (local_softirq_pending())
568 do_softirq_post_smp_call_flush(was_pending);
569
570 local_irq_restore(flags);
571}
572
573/*
574 * smp_call_function_single - Run a function on a specific CPU
575 * @func: The function to run. This must be fast and non-blocking.
576 * @info: An arbitrary pointer to pass to the function.
577 * @wait: If true, wait until function has completed on other CPUs.
578 *
579 * Returns 0 on success, else a negative status code.
580 */
581int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
582 int wait)
583{
584 call_single_data_t *csd;
585 call_single_data_t csd_stack = {
586 .node = { .u_flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC, },
587 };
588 int this_cpu;
589 int err;
590
591 /*
592 * prevent preemption and reschedule on another processor,
593 * as well as CPU removal
594 */
595 this_cpu = get_cpu();
596
597 /*
598 * Can deadlock when called with interrupts disabled.
599 * We allow cpu's that are not yet online though, as no one else can
600 * send smp call function interrupt to this cpu and as such deadlocks
601 * can't happen.
602 */
603 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
604 && !oops_in_progress);
605
606 /*
607 * When @wait we can deadlock when we interrupt between llist_add() and
608 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
609 * csd_lock() on because the interrupt context uses the same csd
610 * storage.
611 */
612 WARN_ON_ONCE(!in_task());
613
614 csd = &csd_stack;
615 if (!wait) {
616 csd = this_cpu_ptr(&csd_data);
617 csd_lock(csd);
618 }
619
620 csd->func = func;
621 csd->info = info;
622#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
623 csd->node.src = smp_processor_id();
624 csd->node.dst = cpu;
625#endif
626
627 err = generic_exec_single(cpu, csd);
628
629 if (wait)
630 csd_lock_wait(csd);
631
632 put_cpu();
633
634 return err;
635}
636EXPORT_SYMBOL(smp_call_function_single);
637
638/**
639 * smp_call_function_single_async() - Run an asynchronous function on a
640 * specific CPU.
641 * @cpu: The CPU to run on.
642 * @csd: Pre-allocated and setup data structure
643 *
644 * Like smp_call_function_single(), but the call is asynchonous and
645 * can thus be done from contexts with disabled interrupts.
646 *
647 * The caller passes his own pre-allocated data structure
648 * (ie: embedded in an object) and is responsible for synchronizing it
649 * such that the IPIs performed on the @csd are strictly serialized.
650 *
651 * If the function is called with one csd which has not yet been
652 * processed by previous call to smp_call_function_single_async(), the
653 * function will return immediately with -EBUSY showing that the csd
654 * object is still in progress.
655 *
656 * NOTE: Be careful, there is unfortunately no current debugging facility to
657 * validate the correctness of this serialization.
658 *
659 * Return: %0 on success or negative errno value on error
660 */
661int smp_call_function_single_async(int cpu, struct __call_single_data *csd)
662{
663 int err = 0;
664
665 preempt_disable();
666
667 if (csd->node.u_flags & CSD_FLAG_LOCK) {
668 err = -EBUSY;
669 goto out;
670 }
671
672 csd->node.u_flags = CSD_FLAG_LOCK;
673 smp_wmb();
674
675 err = generic_exec_single(cpu, csd);
676
677out:
678 preempt_enable();
679
680 return err;
681}
682EXPORT_SYMBOL_GPL(smp_call_function_single_async);
683
684/*
685 * smp_call_function_any - Run a function on any of the given cpus
686 * @mask: The mask of cpus it can run on.
687 * @func: The function to run. This must be fast and non-blocking.
688 * @info: An arbitrary pointer to pass to the function.
689 * @wait: If true, wait until function has completed.
690 *
691 * Returns 0 on success, else a negative status code (if no cpus were online).
692 *
693 * Selection preference:
694 * 1) current cpu if in @mask
695 * 2) any cpu of current node if in @mask
696 * 3) any other online cpu in @mask
697 */
698int smp_call_function_any(const struct cpumask *mask,
699 smp_call_func_t func, void *info, int wait)
700{
701 unsigned int cpu;
702 const struct cpumask *nodemask;
703 int ret;
704
705 /* Try for same CPU (cheapest) */
706 cpu = get_cpu();
707 if (cpumask_test_cpu(cpu, mask))
708 goto call;
709
710 /* Try for same node. */
711 nodemask = cpumask_of_node(cpu_to_node(cpu));
712 for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
713 cpu = cpumask_next_and(cpu, nodemask, mask)) {
714 if (cpu_online(cpu))
715 goto call;
716 }
717
718 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
719 cpu = cpumask_any_and(mask, cpu_online_mask);
720call:
721 ret = smp_call_function_single(cpu, func, info, wait);
722 put_cpu();
723 return ret;
724}
725EXPORT_SYMBOL_GPL(smp_call_function_any);
726
727/*
728 * Flags to be used as scf_flags argument of smp_call_function_many_cond().
729 *
730 * %SCF_WAIT: Wait until function execution is completed
731 * %SCF_RUN_LOCAL: Run also locally if local cpu is set in cpumask
732 */
733#define SCF_WAIT (1U << 0)
734#define SCF_RUN_LOCAL (1U << 1)
735
736static void smp_call_function_many_cond(const struct cpumask *mask,
737 smp_call_func_t func, void *info,
738 unsigned int scf_flags,
739 smp_cond_func_t cond_func)
740{
741 int cpu, last_cpu, this_cpu = smp_processor_id();
742 struct call_function_data *cfd;
743 bool wait = scf_flags & SCF_WAIT;
744 int nr_cpus = 0;
745 bool run_remote = false;
746 bool run_local = false;
747
748 lockdep_assert_preemption_disabled();
749
750 /*
751 * Can deadlock when called with interrupts disabled.
752 * We allow cpu's that are not yet online though, as no one else can
753 * send smp call function interrupt to this cpu and as such deadlocks
754 * can't happen.
755 */
756 if (cpu_online(this_cpu) && !oops_in_progress &&
757 !early_boot_irqs_disabled)
758 lockdep_assert_irqs_enabled();
759
760 /*
761 * When @wait we can deadlock when we interrupt between llist_add() and
762 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
763 * csd_lock() on because the interrupt context uses the same csd
764 * storage.
765 */
766 WARN_ON_ONCE(!in_task());
767
768 /* Check if we need local execution. */
769 if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask))
770 run_local = true;
771
772 /* Check if we need remote execution, i.e., any CPU excluding this one. */
773 cpu = cpumask_first_and(mask, cpu_online_mask);
774 if (cpu == this_cpu)
775 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
776 if (cpu < nr_cpu_ids)
777 run_remote = true;
778
779 if (run_remote) {
780 cfd = this_cpu_ptr(&cfd_data);
781 cpumask_and(cfd->cpumask, mask, cpu_online_mask);
782 __cpumask_clear_cpu(this_cpu, cfd->cpumask);
783
784 cpumask_clear(cfd->cpumask_ipi);
785 for_each_cpu(cpu, cfd->cpumask) {
786 call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
787
788 if (cond_func && !cond_func(cpu, info)) {
789 __cpumask_clear_cpu(cpu, cfd->cpumask);
790 continue;
791 }
792
793 csd_lock(csd);
794 if (wait)
795 csd->node.u_flags |= CSD_TYPE_SYNC;
796 csd->func = func;
797 csd->info = info;
798#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
799 csd->node.src = smp_processor_id();
800 csd->node.dst = cpu;
801#endif
802 trace_csd_queue_cpu(cpu, _RET_IP_, func, csd);
803
804 if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
805 __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
806 nr_cpus++;
807 last_cpu = cpu;
808 }
809 }
810
811 /*
812 * Choose the most efficient way to send an IPI. Note that the
813 * number of CPUs might be zero due to concurrent changes to the
814 * provided mask.
815 */
816 if (nr_cpus == 1)
817 send_call_function_single_ipi(last_cpu);
818 else if (likely(nr_cpus > 1))
819 send_call_function_ipi_mask(cfd->cpumask_ipi);
820 }
821
822 if (run_local && (!cond_func || cond_func(this_cpu, info))) {
823 unsigned long flags;
824
825 local_irq_save(flags);
826 csd_do_func(func, info, NULL);
827 local_irq_restore(flags);
828 }
829
830 if (run_remote && wait) {
831 for_each_cpu(cpu, cfd->cpumask) {
832 call_single_data_t *csd;
833
834 csd = per_cpu_ptr(cfd->csd, cpu);
835 csd_lock_wait(csd);
836 }
837 }
838}
839
840/**
841 * smp_call_function_many(): Run a function on a set of CPUs.
842 * @mask: The set of cpus to run on (only runs on online subset).
843 * @func: The function to run. This must be fast and non-blocking.
844 * @info: An arbitrary pointer to pass to the function.
845 * @wait: Bitmask that controls the operation. If %SCF_WAIT is set, wait
846 * (atomically) until function has completed on other CPUs. If
847 * %SCF_RUN_LOCAL is set, the function will also be run locally
848 * if the local CPU is set in the @cpumask.
849 *
850 * If @wait is true, then returns once @func has returned.
851 *
852 * You must not call this function with disabled interrupts or from a
853 * hardware interrupt handler or from a bottom half handler. Preemption
854 * must be disabled when calling this function.
855 */
856void smp_call_function_many(const struct cpumask *mask,
857 smp_call_func_t func, void *info, bool wait)
858{
859 smp_call_function_many_cond(mask, func, info, wait * SCF_WAIT, NULL);
860}
861EXPORT_SYMBOL(smp_call_function_many);
862
863/**
864 * smp_call_function(): Run a function on all other CPUs.
865 * @func: The function to run. This must be fast and non-blocking.
866 * @info: An arbitrary pointer to pass to the function.
867 * @wait: If true, wait (atomically) until function has completed
868 * on other CPUs.
869 *
870 * Returns 0.
871 *
872 * If @wait is true, then returns once @func has returned; otherwise
873 * it returns just before the target cpu calls @func.
874 *
875 * You must not call this function with disabled interrupts or from a
876 * hardware interrupt handler or from a bottom half handler.
877 */
878void smp_call_function(smp_call_func_t func, void *info, int wait)
879{
880 preempt_disable();
881 smp_call_function_many(cpu_online_mask, func, info, wait);
882 preempt_enable();
883}
884EXPORT_SYMBOL(smp_call_function);
885
886/* Setup configured maximum number of CPUs to activate */
887unsigned int setup_max_cpus = NR_CPUS;
888EXPORT_SYMBOL(setup_max_cpus);
889
890
891/*
892 * Setup routine for controlling SMP activation
893 *
894 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
895 * activation entirely (the MPS table probe still happens, though).
896 *
897 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
898 * greater than 0, limits the maximum number of CPUs activated in
899 * SMP mode to <NUM>.
900 */
901
902void __weak __init arch_disable_smp_support(void) { }
903
904static int __init nosmp(char *str)
905{
906 setup_max_cpus = 0;
907 arch_disable_smp_support();
908
909 return 0;
910}
911
912early_param("nosmp", nosmp);
913
914/* this is hard limit */
915static int __init nrcpus(char *str)
916{
917 int nr_cpus;
918
919 if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids)
920 set_nr_cpu_ids(nr_cpus);
921
922 return 0;
923}
924
925early_param("nr_cpus", nrcpus);
926
927static int __init maxcpus(char *str)
928{
929 get_option(&str, &setup_max_cpus);
930 if (setup_max_cpus == 0)
931 arch_disable_smp_support();
932
933 return 0;
934}
935
936early_param("maxcpus", maxcpus);
937
938#if (NR_CPUS > 1) && !defined(CONFIG_FORCE_NR_CPUS)
939/* Setup number of possible processor ids */
940unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
941EXPORT_SYMBOL(nr_cpu_ids);
942#endif
943
944/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
945void __init setup_nr_cpu_ids(void)
946{
947 set_nr_cpu_ids(find_last_bit(cpumask_bits(cpu_possible_mask), NR_CPUS) + 1);
948}
949
950/* Called by boot processor to activate the rest. */
951void __init smp_init(void)
952{
953 int num_nodes, num_cpus;
954
955 idle_threads_init();
956 cpuhp_threads_init();
957
958 pr_info("Bringing up secondary CPUs ...\n");
959
960 bringup_nonboot_cpus(setup_max_cpus);
961
962 num_nodes = num_online_nodes();
963 num_cpus = num_online_cpus();
964 pr_info("Brought up %d node%s, %d CPU%s\n",
965 num_nodes, (num_nodes > 1 ? "s" : ""),
966 num_cpus, (num_cpus > 1 ? "s" : ""));
967
968 /* Any cleanup work */
969 smp_cpus_done(setup_max_cpus);
970}
971
972/*
973 * on_each_cpu_cond(): Call a function on each processor for which
974 * the supplied function cond_func returns true, optionally waiting
975 * for all the required CPUs to finish. This may include the local
976 * processor.
977 * @cond_func: A callback function that is passed a cpu id and
978 * the info parameter. The function is called
979 * with preemption disabled. The function should
980 * return a blooean value indicating whether to IPI
981 * the specified CPU.
982 * @func: The function to run on all applicable CPUs.
983 * This must be fast and non-blocking.
984 * @info: An arbitrary pointer to pass to both functions.
985 * @wait: If true, wait (atomically) until function has
986 * completed on other CPUs.
987 *
988 * Preemption is disabled to protect against CPUs going offline but not online.
989 * CPUs going online during the call will not be seen or sent an IPI.
990 *
991 * You must not call this function with disabled interrupts or
992 * from a hardware interrupt handler or from a bottom half handler.
993 */
994void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
995 void *info, bool wait, const struct cpumask *mask)
996{
997 unsigned int scf_flags = SCF_RUN_LOCAL;
998
999 if (wait)
1000 scf_flags |= SCF_WAIT;
1001
1002 preempt_disable();
1003 smp_call_function_many_cond(mask, func, info, scf_flags, cond_func);
1004 preempt_enable();
1005}
1006EXPORT_SYMBOL(on_each_cpu_cond_mask);
1007
1008static void do_nothing(void *unused)
1009{
1010}
1011
1012/**
1013 * kick_all_cpus_sync - Force all cpus out of idle
1014 *
1015 * Used to synchronize the update of pm_idle function pointer. It's
1016 * called after the pointer is updated and returns after the dummy
1017 * callback function has been executed on all cpus. The execution of
1018 * the function can only happen on the remote cpus after they have
1019 * left the idle function which had been called via pm_idle function
1020 * pointer. So it's guaranteed that nothing uses the previous pointer
1021 * anymore.
1022 */
1023void kick_all_cpus_sync(void)
1024{
1025 /* Make sure the change is visible before we kick the cpus */
1026 smp_mb();
1027 smp_call_function(do_nothing, NULL, 1);
1028}
1029EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
1030
1031/**
1032 * wake_up_all_idle_cpus - break all cpus out of idle
1033 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
1034 * including idle polling cpus, for non-idle cpus, we will do nothing
1035 * for them.
1036 */
1037void wake_up_all_idle_cpus(void)
1038{
1039 int cpu;
1040
1041 for_each_possible_cpu(cpu) {
1042 preempt_disable();
1043 if (cpu != smp_processor_id() && cpu_online(cpu))
1044 wake_up_if_idle(cpu);
1045 preempt_enable();
1046 }
1047}
1048EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
1049
1050/**
1051 * struct smp_call_on_cpu_struct - Call a function on a specific CPU
1052 * @work: &work_struct
1053 * @done: &completion to signal
1054 * @func: function to call
1055 * @data: function's data argument
1056 * @ret: return value from @func
1057 * @cpu: target CPU (%-1 for any CPU)
1058 *
1059 * Used to call a function on a specific cpu and wait for it to return.
1060 * Optionally make sure the call is done on a specified physical cpu via vcpu
1061 * pinning in order to support virtualized environments.
1062 */
1063struct smp_call_on_cpu_struct {
1064 struct work_struct work;
1065 struct completion done;
1066 int (*func)(void *);
1067 void *data;
1068 int ret;
1069 int cpu;
1070};
1071
1072static void smp_call_on_cpu_callback(struct work_struct *work)
1073{
1074 struct smp_call_on_cpu_struct *sscs;
1075
1076 sscs = container_of(work, struct smp_call_on_cpu_struct, work);
1077 if (sscs->cpu >= 0)
1078 hypervisor_pin_vcpu(sscs->cpu);
1079 sscs->ret = sscs->func(sscs->data);
1080 if (sscs->cpu >= 0)
1081 hypervisor_pin_vcpu(-1);
1082
1083 complete(&sscs->done);
1084}
1085
1086int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
1087{
1088 struct smp_call_on_cpu_struct sscs = {
1089 .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
1090 .func = func,
1091 .data = par,
1092 .cpu = phys ? cpu : -1,
1093 };
1094
1095 INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
1096
1097 if (cpu >= nr_cpu_ids || !cpu_online(cpu))
1098 return -ENXIO;
1099
1100 queue_work_on(cpu, system_wq, &sscs.work);
1101 wait_for_completion(&sscs.done);
1102
1103 return sscs.ret;
1104}
1105EXPORT_SYMBOL_GPL(smp_call_on_cpu);