Line data Source code
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/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 :
28 : #include "smpboot.h"
29 : #include "sched/smp.h"
30 :
31 : #define CSD_TYPE(_csd) ((_csd)->node.u_flags & CSD_FLAG_TYPE_MASK)
32 :
33 : struct call_function_data {
34 : call_single_data_t __percpu *csd;
35 : cpumask_var_t cpumask;
36 : cpumask_var_t cpumask_ipi;
37 : };
38 :
39 : static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data);
40 :
41 : static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
42 :
43 : static void flush_smp_call_function_queue(bool warn_cpu_offline);
44 :
45 4 : int smpcfd_prepare_cpu(unsigned int cpu)
46 : {
47 4 : struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
48 :
49 4 : if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
50 : cpu_to_node(cpu)))
51 : return -ENOMEM;
52 4 : if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
53 : cpu_to_node(cpu))) {
54 : free_cpumask_var(cfd->cpumask);
55 : return -ENOMEM;
56 : }
57 4 : cfd->csd = alloc_percpu(call_single_data_t);
58 4 : if (!cfd->csd) {
59 0 : free_cpumask_var(cfd->cpumask);
60 0 : free_cpumask_var(cfd->cpumask_ipi);
61 0 : return -ENOMEM;
62 : }
63 :
64 : return 0;
65 : }
66 :
67 0 : int smpcfd_dead_cpu(unsigned int cpu)
68 : {
69 0 : struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
70 :
71 0 : free_cpumask_var(cfd->cpumask);
72 0 : free_cpumask_var(cfd->cpumask_ipi);
73 0 : free_percpu(cfd->csd);
74 0 : return 0;
75 : }
76 :
77 0 : int smpcfd_dying_cpu(unsigned int cpu)
78 : {
79 : /*
80 : * The IPIs for the smp-call-function callbacks queued by other
81 : * CPUs might arrive late, either due to hardware latencies or
82 : * because this CPU disabled interrupts (inside stop-machine)
83 : * before the IPIs were sent. So flush out any pending callbacks
84 : * explicitly (without waiting for the IPIs to arrive), to
85 : * ensure that the outgoing CPU doesn't go offline with work
86 : * still pending.
87 : */
88 0 : flush_smp_call_function_queue(false);
89 0 : irq_work_run();
90 0 : return 0;
91 : }
92 :
93 1 : void __init call_function_init(void)
94 : {
95 1 : int i;
96 :
97 6 : for_each_possible_cpu(i)
98 5 : init_llist_head(&per_cpu(call_single_queue, i));
99 :
100 1 : smpcfd_prepare_cpu(smp_processor_id());
101 1 : }
102 :
103 : #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
104 :
105 : static DEFINE_PER_CPU(call_single_data_t *, cur_csd);
106 : static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);
107 : static DEFINE_PER_CPU(void *, cur_csd_info);
108 :
109 : #define CSD_LOCK_TIMEOUT (5ULL * NSEC_PER_SEC)
110 : static atomic_t csd_bug_count = ATOMIC_INIT(0);
111 :
112 : /* Record current CSD work for current CPU, NULL to erase. */
113 : static void csd_lock_record(call_single_data_t *csd)
114 : {
115 : if (!csd) {
116 : smp_mb(); /* NULL cur_csd after unlock. */
117 : __this_cpu_write(cur_csd, NULL);
118 : return;
119 : }
120 : __this_cpu_write(cur_csd_func, csd->func);
121 : __this_cpu_write(cur_csd_info, csd->info);
122 : smp_wmb(); /* func and info before csd. */
123 : __this_cpu_write(cur_csd, csd);
124 : smp_mb(); /* Update cur_csd before function call. */
125 : /* Or before unlock, as the case may be. */
126 : }
127 :
128 : static __always_inline int csd_lock_wait_getcpu(call_single_data_t *csd)
129 : {
130 : unsigned int csd_type;
131 :
132 : csd_type = CSD_TYPE(csd);
133 : if (csd_type == CSD_TYPE_ASYNC || csd_type == CSD_TYPE_SYNC)
134 : return csd->node.dst; /* Other CSD_TYPE_ values might not have ->dst. */
135 : return -1;
136 : }
137 :
138 : /*
139 : * Complain if too much time spent waiting. Note that only
140 : * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
141 : * so waiting on other types gets much less information.
142 : */
143 : static __always_inline bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id)
144 : {
145 : int cpu = -1;
146 : int cpux;
147 : bool firsttime;
148 : u64 ts2, ts_delta;
149 : call_single_data_t *cpu_cur_csd;
150 : unsigned int flags = READ_ONCE(csd->node.u_flags);
151 :
152 : if (!(flags & CSD_FLAG_LOCK)) {
153 : if (!unlikely(*bug_id))
154 : return true;
155 : cpu = csd_lock_wait_getcpu(csd);
156 : pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
157 : *bug_id, raw_smp_processor_id(), cpu);
158 : return true;
159 : }
160 :
161 : ts2 = sched_clock();
162 : ts_delta = ts2 - *ts1;
163 : if (likely(ts_delta <= CSD_LOCK_TIMEOUT))
164 : return false;
165 :
166 : firsttime = !*bug_id;
167 : if (firsttime)
168 : *bug_id = atomic_inc_return(&csd_bug_count);
169 : cpu = csd_lock_wait_getcpu(csd);
170 : if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu))
171 : cpux = 0;
172 : else
173 : cpux = cpu;
174 : cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */
175 : pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %llu ns for CPU#%02d %pS(%ps).\n",
176 : firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), ts2 - ts0,
177 : cpu, csd->func, csd->info);
178 : if (cpu_cur_csd && csd != cpu_cur_csd) {
179 : pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
180 : *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)),
181 : READ_ONCE(per_cpu(cur_csd_info, cpux)));
182 : } else {
183 : pr_alert("\tcsd: CSD lock (#%d) %s.\n",
184 : *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
185 : }
186 : if (cpu >= 0) {
187 : if (!trigger_single_cpu_backtrace(cpu))
188 : dump_cpu_task(cpu);
189 : if (!cpu_cur_csd) {
190 : pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
191 : arch_send_call_function_single_ipi(cpu);
192 : }
193 : }
194 : dump_stack();
195 : *ts1 = ts2;
196 :
197 : return false;
198 : }
199 :
200 : /*
201 : * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
202 : *
203 : * For non-synchronous ipi calls the csd can still be in use by the
204 : * previous function call. For multi-cpu calls its even more interesting
205 : * as we'll have to ensure no other cpu is observing our csd.
206 : */
207 : static __always_inline void csd_lock_wait(call_single_data_t *csd)
208 : {
209 : int bug_id = 0;
210 : u64 ts0, ts1;
211 :
212 : ts1 = ts0 = sched_clock();
213 : for (;;) {
214 : if (csd_lock_wait_toolong(csd, ts0, &ts1, &bug_id))
215 : break;
216 : cpu_relax();
217 : }
218 : smp_acquire__after_ctrl_dep();
219 : }
220 :
221 : #else
222 6382 : static void csd_lock_record(call_single_data_t *csd)
223 : {
224 3351 : }
225 :
226 422 : static __always_inline void csd_lock_wait(call_single_data_t *csd)
227 : {
228 66113 : smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
229 173 : }
230 : #endif
231 :
232 303 : static __always_inline void csd_lock(call_single_data_t *csd)
233 : {
234 826 : csd_lock_wait(csd);
235 413 : csd->node.u_flags |= CSD_FLAG_LOCK;
236 :
237 : /*
238 : * prevent CPU from reordering the above assignment
239 : * to ->flags with any subsequent assignments to other
240 : * fields of the specified call_single_data_t structure:
241 : */
242 413 : smp_wmb();
243 303 : }
244 :
245 3195 : static __always_inline void csd_unlock(call_single_data_t *csd)
246 : {
247 0 : WARN_ON(!(csd->node.u_flags & CSD_FLAG_LOCK));
248 :
249 : /*
250 : * ensure we're all done before releasing data:
251 : */
252 3195 : smp_store_release(&csd->node.u_flags, 0);
253 : }
254 :
255 : static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
256 :
257 7652 : void __smp_call_single_queue(int cpu, struct llist_node *node)
258 : {
259 : /*
260 : * The list addition should be visible before sending the IPI
261 : * handler locks the list to pull the entry off it because of
262 : * normal cache coherency rules implied by spinlocks.
263 : *
264 : * If IPIs can go out of order to the cache coherency protocol
265 : * in an architecture, sufficient synchronisation should be added
266 : * to arch code to make it appear to obey cache coherency WRT
267 : * locking and barrier primitives. Generic code isn't really
268 : * equipped to do the right thing...
269 : */
270 7652 : if (llist_add(node, &per_cpu(call_single_queue, cpu)))
271 7637 : send_call_function_single_ipi(cpu);
272 7652 : }
273 :
274 : /*
275 : * Insert a previously allocated call_single_data_t element
276 : * for execution on the given CPU. data must already have
277 : * ->func, ->info, and ->flags set.
278 : */
279 3085 : static int generic_exec_single(int cpu, call_single_data_t *csd)
280 : {
281 3085 : if (cpu == smp_processor_id()) {
282 9 : smp_call_func_t func = csd->func;
283 9 : void *info = csd->info;
284 9 : unsigned long flags;
285 :
286 : /*
287 : * We can unlock early even for the synchronous on-stack case,
288 : * since we're doing this from the same CPU..
289 : */
290 9 : csd_lock_record(csd);
291 9 : csd_unlock(csd);
292 18 : local_irq_save(flags);
293 9 : func(info);
294 9 : csd_lock_record(NULL);
295 9 : local_irq_restore(flags);
296 9 : return 0;
297 : }
298 :
299 6152 : if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
300 0 : csd_unlock(csd);
301 0 : return -ENXIO;
302 : }
303 :
304 3076 : __smp_call_single_queue(cpu, &csd->node.llist);
305 :
306 3076 : return 0;
307 : }
308 :
309 : /**
310 : * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
311 : *
312 : * Invoked by arch to handle an IPI for call function single.
313 : * Must be called with interrupts disabled.
314 : */
315 7711 : void generic_smp_call_function_single_interrupt(void)
316 : {
317 7711 : flush_smp_call_function_queue(true);
318 7715 : }
319 :
320 : /**
321 : * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
322 : *
323 : * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
324 : * offline CPU. Skip this check if set to 'false'.
325 : *
326 : * Flush any pending smp-call-function callbacks queued on this CPU. This is
327 : * invoked by the generic IPI handler, as well as by a CPU about to go offline,
328 : * to ensure that all pending IPI callbacks are run before it goes completely
329 : * offline.
330 : *
331 : * Loop through the call_single_queue and run all the queued callbacks.
332 : * Must be called with interrupts disabled.
333 : */
334 7741 : static void flush_smp_call_function_queue(bool warn_cpu_offline)
335 : {
336 7741 : call_single_data_t *csd, *csd_next;
337 7741 : struct llist_node *entry, *prev;
338 7741 : struct llist_head *head;
339 7741 : static bool warned;
340 :
341 15486 : lockdep_assert_irqs_disabled();
342 :
343 7744 : head = this_cpu_ptr(&call_single_queue);
344 7745 : entry = llist_del_all(head);
345 7750 : entry = llist_reverse_order(entry);
346 :
347 : /* There shouldn't be any pending callbacks on an offline CPU. */
348 7747 : if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
349 : !warned && !llist_empty(head))) {
350 0 : warned = true;
351 0 : WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
352 :
353 : /*
354 : * We don't have to use the _safe() variant here
355 : * because we are not invoking the IPI handlers yet.
356 : */
357 0 : llist_for_each_entry(csd, entry, node.llist) {
358 0 : switch (CSD_TYPE(csd)) {
359 0 : case CSD_TYPE_ASYNC:
360 : case CSD_TYPE_SYNC:
361 : case CSD_TYPE_IRQ_WORK:
362 0 : pr_warn("IPI callback %pS sent to offline CPU\n",
363 : csd->func);
364 0 : break;
365 :
366 0 : case CSD_TYPE_TTWU:
367 0 : pr_warn("IPI task-wakeup sent to offline CPU\n");
368 0 : break;
369 :
370 0 : default:
371 0 : pr_warn("IPI callback, unknown type %d, sent to offline CPU\n",
372 : CSD_TYPE(csd));
373 0 : break;
374 : }
375 : }
376 : }
377 :
378 : /*
379 : * First; run all SYNC callbacks, people are waiting for us.
380 : */
381 : prev = NULL;
382 23258 : llist_for_each_entry_safe(csd, csd_next, entry, node.llist) {
383 : /* Do we wait until *after* callback? */
384 7755 : if (CSD_TYPE(csd) == CSD_TYPE_SYNC) {
385 150 : smp_call_func_t func = csd->func;
386 150 : void *info = csd->info;
387 :
388 150 : if (prev) {
389 0 : prev->next = &csd_next->node.llist;
390 : } else {
391 150 : entry = &csd_next->node.llist;
392 : }
393 :
394 150 : csd_lock_record(csd);
395 150 : func(info);
396 155 : csd_unlock(csd);
397 15655 : csd_lock_record(NULL);
398 : } else {
399 7605 : prev = &csd->node.llist;
400 : }
401 : }
402 :
403 7748 : if (!entry)
404 : return;
405 :
406 : /*
407 : * Second; run all !SYNC callbacks.
408 : */
409 : prev = NULL;
410 22797 : llist_for_each_entry_safe(csd, csd_next, entry, node.llist) {
411 7604 : int type = CSD_TYPE(csd);
412 :
413 7604 : if (type != CSD_TYPE_TTWU) {
414 3031 : if (prev) {
415 0 : prev->next = &csd_next->node.llist;
416 : } else {
417 3031 : entry = &csd_next->node.llist;
418 : }
419 :
420 3031 : if (type == CSD_TYPE_ASYNC) {
421 3031 : smp_call_func_t func = csd->func;
422 3031 : void *info = csd->info;
423 :
424 3031 : csd_lock_record(csd);
425 3031 : csd_unlock(csd);
426 3031 : func(info);
427 18224 : csd_lock_record(NULL);
428 0 : } else if (type == CSD_TYPE_IRQ_WORK) {
429 0 : irq_work_single(csd);
430 : }
431 :
432 : } else {
433 4573 : prev = &csd->node.llist;
434 : }
435 : }
436 :
437 : /*
438 : * Third; only CSD_TYPE_TTWU is left, issue those.
439 : */
440 7589 : if (entry)
441 4559 : sched_ttwu_pending(entry);
442 : }
443 :
444 8006 : void flush_smp_call_function_from_idle(void)
445 : {
446 8006 : unsigned long flags;
447 :
448 8006 : if (llist_empty(this_cpu_ptr(&call_single_queue)))
449 : return;
450 :
451 62 : local_irq_save(flags);
452 31 : flush_smp_call_function_queue(true);
453 31 : if (local_softirq_pending())
454 8 : do_softirq();
455 :
456 31 : local_irq_restore(flags);
457 : }
458 :
459 : /*
460 : * smp_call_function_single - Run a function on a specific CPU
461 : * @func: The function to run. This must be fast and non-blocking.
462 : * @info: An arbitrary pointer to pass to the function.
463 : * @wait: If true, wait until function has completed on other CPUs.
464 : *
465 : * Returns 0 on success, else a negative status code.
466 : */
467 357 : int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
468 : int wait)
469 : {
470 357 : call_single_data_t *csd;
471 357 : call_single_data_t csd_stack = {
472 : .node = { .u_flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC, },
473 : };
474 357 : int this_cpu;
475 357 : int err;
476 :
477 : /*
478 : * prevent preemption and reschedule on another processor,
479 : * as well as CPU removal
480 : */
481 357 : this_cpu = get_cpu();
482 :
483 : /*
484 : * Can deadlock when called with interrupts disabled.
485 : * We allow cpu's that are not yet online though, as no one else can
486 : * send smp call function interrupt to this cpu and as such deadlocks
487 : * can't happen.
488 : */
489 357 : WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
490 : && !oops_in_progress);
491 :
492 : /*
493 : * When @wait we can deadlock when we interrupt between llist_add() and
494 : * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
495 : * csd_lock() on because the interrupt context uses the same csd
496 : * storage.
497 : */
498 357 : WARN_ON_ONCE(!in_task());
499 :
500 357 : csd = &csd_stack;
501 357 : if (!wait) {
502 303 : csd = this_cpu_ptr(&csd_data);
503 303 : csd_lock(csd);
504 : }
505 :
506 357 : csd->func = func;
507 357 : csd->info = info;
508 : #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
509 : csd->node.src = smp_processor_id();
510 : csd->node.dst = cpu;
511 : #endif
512 :
513 357 : err = generic_exec_single(cpu, csd);
514 :
515 357 : if (wait)
516 14341 : csd_lock_wait(csd);
517 :
518 357 : put_cpu();
519 :
520 357 : return err;
521 : }
522 : EXPORT_SYMBOL(smp_call_function_single);
523 :
524 : /**
525 : * smp_call_function_single_async(): Run an asynchronous function on a
526 : * specific CPU.
527 : * @cpu: The CPU to run on.
528 : * @csd: Pre-allocated and setup data structure
529 : *
530 : * Like smp_call_function_single(), but the call is asynchonous and
531 : * can thus be done from contexts with disabled interrupts.
532 : *
533 : * The caller passes his own pre-allocated data structure
534 : * (ie: embedded in an object) and is responsible for synchronizing it
535 : * such that the IPIs performed on the @csd are strictly serialized.
536 : *
537 : * If the function is called with one csd which has not yet been
538 : * processed by previous call to smp_call_function_single_async(), the
539 : * function will return immediately with -EBUSY showing that the csd
540 : * object is still in progress.
541 : *
542 : * NOTE: Be careful, there is unfortunately no current debugging facility to
543 : * validate the correctness of this serialization.
544 : */
545 2728 : int smp_call_function_single_async(int cpu, call_single_data_t *csd)
546 : {
547 2728 : int err = 0;
548 :
549 2728 : preempt_disable();
550 :
551 2728 : if (csd->node.u_flags & CSD_FLAG_LOCK) {
552 0 : err = -EBUSY;
553 0 : goto out;
554 : }
555 :
556 2728 : csd->node.u_flags = CSD_FLAG_LOCK;
557 2728 : smp_wmb();
558 :
559 2728 : err = generic_exec_single(cpu, csd);
560 :
561 2728 : out:
562 2728 : preempt_enable();
563 :
564 2728 : return err;
565 : }
566 : EXPORT_SYMBOL_GPL(smp_call_function_single_async);
567 :
568 : /*
569 : * smp_call_function_any - Run a function on any of the given cpus
570 : * @mask: The mask of cpus it can run on.
571 : * @func: The function to run. This must be fast and non-blocking.
572 : * @info: An arbitrary pointer to pass to the function.
573 : * @wait: If true, wait until function has completed.
574 : *
575 : * Returns 0 on success, else a negative status code (if no cpus were online).
576 : *
577 : * Selection preference:
578 : * 1) current cpu if in @mask
579 : * 2) any cpu of current node if in @mask
580 : * 3) any other online cpu in @mask
581 : */
582 0 : int smp_call_function_any(const struct cpumask *mask,
583 : smp_call_func_t func, void *info, int wait)
584 : {
585 0 : unsigned int cpu;
586 0 : const struct cpumask *nodemask;
587 0 : int ret;
588 :
589 : /* Try for same CPU (cheapest) */
590 0 : cpu = get_cpu();
591 0 : if (cpumask_test_cpu(cpu, mask))
592 0 : goto call;
593 :
594 : /* Try for same node. */
595 0 : nodemask = cpumask_of_node(cpu_to_node(cpu));
596 0 : for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
597 0 : cpu = cpumask_next_and(cpu, nodemask, mask)) {
598 0 : if (cpu_online(cpu))
599 0 : goto call;
600 : }
601 :
602 : /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
603 0 : cpu = cpumask_any_and(mask, cpu_online_mask);
604 0 : call:
605 0 : ret = smp_call_function_single(cpu, func, info, wait);
606 0 : put_cpu();
607 0 : return ret;
608 : }
609 : EXPORT_SYMBOL_GPL(smp_call_function_any);
610 :
611 1644 : static void smp_call_function_many_cond(const struct cpumask *mask,
612 : smp_call_func_t func, void *info,
613 : bool wait, smp_cond_func_t cond_func)
614 : {
615 1644 : struct call_function_data *cfd;
616 1644 : int cpu, next_cpu, this_cpu = smp_processor_id();
617 :
618 : /*
619 : * Can deadlock when called with interrupts disabled.
620 : * We allow cpu's that are not yet online though, as no one else can
621 : * send smp call function interrupt to this cpu and as such deadlocks
622 : * can't happen.
623 : */
624 1647 : WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
625 : && !oops_in_progress && !early_boot_irqs_disabled);
626 :
627 : /*
628 : * When @wait we can deadlock when we interrupt between llist_add() and
629 : * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
630 : * csd_lock() on because the interrupt context uses the same csd
631 : * storage.
632 : */
633 1644 : WARN_ON_ONCE(!in_task());
634 :
635 : /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
636 1644 : cpu = cpumask_first_and(mask, cpu_online_mask);
637 1644 : if (cpu == this_cpu)
638 1383 : cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
639 :
640 : /* No online cpus? We're done. */
641 1644 : if (cpu >= nr_cpu_ids)
642 : return;
643 :
644 : /* Do we have another CPU which isn't us? */
645 315 : next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
646 315 : if (next_cpu == this_cpu)
647 137 : next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
648 :
649 : /* Fastpath: do that cpu by itself. */
650 315 : if (next_cpu >= nr_cpu_ids) {
651 275 : if (!cond_func || cond_func(cpu, info))
652 44 : smp_call_function_single(cpu, func, info, wait);
653 275 : return;
654 : }
655 :
656 40 : cfd = this_cpu_ptr(&cfd_data);
657 :
658 40 : cpumask_and(cfd->cpumask, mask, cpu_online_mask);
659 40 : __cpumask_clear_cpu(this_cpu, cfd->cpumask);
660 :
661 : /* Some callers race with other cpus changing the passed mask */
662 40 : if (unlikely(!cpumask_weight(cfd->cpumask)))
663 : return;
664 :
665 40 : cpumask_clear(cfd->cpumask_ipi);
666 199 : for_each_cpu(cpu, cfd->cpumask) {
667 119 : call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
668 :
669 119 : if (cond_func && !cond_func(cpu, info))
670 9 : continue;
671 :
672 110 : csd_lock(csd);
673 110 : if (wait)
674 110 : csd->node.u_flags |= CSD_TYPE_SYNC;
675 110 : csd->func = func;
676 110 : csd->info = info;
677 : #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
678 : csd->node.src = smp_processor_id();
679 : csd->node.dst = cpu;
680 : #endif
681 110 : if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu)))
682 269 : __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
683 : }
684 :
685 : /* Send a message to all CPUs in the map */
686 40 : arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
687 :
688 40 : if (wait) {
689 159 : for_each_cpu(cpu, cfd->cpumask) {
690 119 : call_single_data_t *csd;
691 :
692 119 : csd = per_cpu_ptr(cfd->csd, cpu);
693 278 : csd_lock_wait(csd);
694 : }
695 : }
696 : }
697 :
698 : /**
699 : * smp_call_function_many(): Run a function on a set of other CPUs.
700 : * @mask: The set of cpus to run on (only runs on online subset).
701 : * @func: The function to run. This must be fast and non-blocking.
702 : * @info: An arbitrary pointer to pass to the function.
703 : * @wait: If true, wait (atomically) until function has completed
704 : * on other CPUs.
705 : *
706 : * If @wait is true, then returns once @func has returned.
707 : *
708 : * You must not call this function with disabled interrupts or from a
709 : * hardware interrupt handler or from a bottom half handler. Preemption
710 : * must be disabled when calling this function.
711 : */
712 334 : void smp_call_function_many(const struct cpumask *mask,
713 : smp_call_func_t func, void *info, bool wait)
714 : {
715 178 : smp_call_function_many_cond(mask, func, info, wait, NULL);
716 178 : }
717 : EXPORT_SYMBOL(smp_call_function_many);
718 :
719 : /**
720 : * smp_call_function(): Run a function on all other CPUs.
721 : * @func: The function to run. This must be fast and non-blocking.
722 : * @info: An arbitrary pointer to pass to the function.
723 : * @wait: If true, wait (atomically) until function has completed
724 : * on other CPUs.
725 : *
726 : * Returns 0.
727 : *
728 : * If @wait is true, then returns once @func has returned; otherwise
729 : * it returns just before the target cpu calls @func.
730 : *
731 : * You must not call this function with disabled interrupts or from a
732 : * hardware interrupt handler or from a bottom half handler.
733 : */
734 156 : void smp_call_function(smp_call_func_t func, void *info, int wait)
735 : {
736 156 : preempt_disable();
737 156 : smp_call_function_many(cpu_online_mask, func, info, wait);
738 156 : preempt_enable();
739 156 : }
740 : EXPORT_SYMBOL(smp_call_function);
741 :
742 : /* Setup configured maximum number of CPUs to activate */
743 : unsigned int setup_max_cpus = NR_CPUS;
744 : EXPORT_SYMBOL(setup_max_cpus);
745 :
746 :
747 : /*
748 : * Setup routine for controlling SMP activation
749 : *
750 : * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
751 : * activation entirely (the MPS table probe still happens, though).
752 : *
753 : * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
754 : * greater than 0, limits the maximum number of CPUs activated in
755 : * SMP mode to <NUM>.
756 : */
757 :
758 0 : void __weak arch_disable_smp_support(void) { }
759 :
760 0 : static int __init nosmp(char *str)
761 : {
762 0 : setup_max_cpus = 0;
763 0 : arch_disable_smp_support();
764 :
765 0 : return 0;
766 : }
767 :
768 : early_param("nosmp", nosmp);
769 :
770 : /* this is hard limit */
771 0 : static int __init nrcpus(char *str)
772 : {
773 0 : int nr_cpus;
774 :
775 0 : if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids)
776 0 : nr_cpu_ids = nr_cpus;
777 :
778 0 : return 0;
779 : }
780 :
781 : early_param("nr_cpus", nrcpus);
782 :
783 0 : static int __init maxcpus(char *str)
784 : {
785 0 : get_option(&str, &setup_max_cpus);
786 0 : if (setup_max_cpus == 0)
787 0 : arch_disable_smp_support();
788 :
789 0 : return 0;
790 : }
791 :
792 : early_param("maxcpus", maxcpus);
793 :
794 : /* Setup number of possible processor ids */
795 : unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
796 : EXPORT_SYMBOL(nr_cpu_ids);
797 :
798 : /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
799 1 : void __init setup_nr_cpu_ids(void)
800 : {
801 1 : nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
802 1 : }
803 :
804 : /* Called by boot processor to activate the rest. */
805 1 : void __init smp_init(void)
806 : {
807 1 : int num_nodes, num_cpus;
808 :
809 1 : idle_threads_init();
810 1 : cpuhp_threads_init();
811 :
812 1 : pr_info("Bringing up secondary CPUs ...\n");
813 :
814 1 : bringup_nonboot_cpus(setup_max_cpus);
815 :
816 1 : num_nodes = num_online_nodes();
817 1 : num_cpus = num_online_cpus();
818 2 : pr_info("Brought up %d node%s, %d CPU%s\n",
819 : num_nodes, (num_nodes > 1 ? "s" : ""),
820 : num_cpus, (num_cpus > 1 ? "s" : ""));
821 :
822 : /* Any cleanup work */
823 1 : smp_cpus_done(setup_max_cpus);
824 1 : }
825 :
826 : /*
827 : * Call a function on all processors. May be used during early boot while
828 : * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
829 : * of local_irq_disable/enable().
830 : */
831 156 : void on_each_cpu(smp_call_func_t func, void *info, int wait)
832 : {
833 156 : unsigned long flags;
834 :
835 156 : preempt_disable();
836 156 : smp_call_function(func, info, wait);
837 312 : local_irq_save(flags);
838 156 : func(info);
839 156 : local_irq_restore(flags);
840 156 : preempt_enable();
841 156 : }
842 : EXPORT_SYMBOL(on_each_cpu);
843 :
844 : /**
845 : * on_each_cpu_mask(): Run a function on processors specified by
846 : * cpumask, which may include the local processor.
847 : * @mask: The set of cpus to run on (only runs on online subset).
848 : * @func: The function to run. This must be fast and non-blocking.
849 : * @info: An arbitrary pointer to pass to the function.
850 : * @wait: If true, wait (atomically) until function has completed
851 : * on other CPUs.
852 : *
853 : * If @wait is true, then returns once @func has returned.
854 : *
855 : * You must not call this function with disabled interrupts or from a
856 : * hardware interrupt handler or from a bottom half handler. The
857 : * exception is that it may be used during early boot while
858 : * early_boot_irqs_disabled is set.
859 : */
860 0 : void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
861 : void *info, bool wait)
862 : {
863 0 : int cpu = get_cpu();
864 :
865 0 : smp_call_function_many(mask, func, info, wait);
866 0 : if (cpumask_test_cpu(cpu, mask)) {
867 0 : unsigned long flags;
868 0 : local_irq_save(flags);
869 0 : func(info);
870 0 : local_irq_restore(flags);
871 : }
872 0 : put_cpu();
873 0 : }
874 : EXPORT_SYMBOL(on_each_cpu_mask);
875 :
876 : /*
877 : * on_each_cpu_cond(): Call a function on each processor for which
878 : * the supplied function cond_func returns true, optionally waiting
879 : * for all the required CPUs to finish. This may include the local
880 : * processor.
881 : * @cond_func: A callback function that is passed a cpu id and
882 : * the info parameter. The function is called
883 : * with preemption disabled. The function should
884 : * return a blooean value indicating whether to IPI
885 : * the specified CPU.
886 : * @func: The function to run on all applicable CPUs.
887 : * This must be fast and non-blocking.
888 : * @info: An arbitrary pointer to pass to both functions.
889 : * @wait: If true, wait (atomically) until function has
890 : * completed on other CPUs.
891 : *
892 : * Preemption is disabled to protect against CPUs going offline but not online.
893 : * CPUs going online during the call will not be seen or sent an IPI.
894 : *
895 : * You must not call this function with disabled interrupts or
896 : * from a hardware interrupt handler or from a bottom half handler.
897 : */
898 1310 : void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
899 : void *info, bool wait, const struct cpumask *mask)
900 : {
901 1310 : int cpu = get_cpu();
902 :
903 1310 : smp_call_function_many_cond(mask, func, info, wait, cond_func);
904 1310 : if (cpumask_test_cpu(cpu, mask) && cond_func(cpu, info)) {
905 1308 : unsigned long flags;
906 :
907 2616 : local_irq_save(flags);
908 1308 : func(info);
909 1308 : local_irq_restore(flags);
910 : }
911 1310 : put_cpu();
912 1310 : }
913 : EXPORT_SYMBOL(on_each_cpu_cond_mask);
914 :
915 3 : void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
916 : void *info, bool wait)
917 : {
918 3 : on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
919 3 : }
920 : EXPORT_SYMBOL(on_each_cpu_cond);
921 :
922 0 : static void do_nothing(void *unused)
923 : {
924 0 : }
925 :
926 : /**
927 : * kick_all_cpus_sync - Force all cpus out of idle
928 : *
929 : * Used to synchronize the update of pm_idle function pointer. It's
930 : * called after the pointer is updated and returns after the dummy
931 : * callback function has been executed on all cpus. The execution of
932 : * the function can only happen on the remote cpus after they have
933 : * left the idle function which had been called via pm_idle function
934 : * pointer. So it's guaranteed that nothing uses the previous pointer
935 : * anymore.
936 : */
937 0 : void kick_all_cpus_sync(void)
938 : {
939 : /* Make sure the change is visible before we kick the cpus */
940 0 : smp_mb();
941 0 : smp_call_function(do_nothing, NULL, 1);
942 0 : }
943 : EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
944 :
945 : /**
946 : * wake_up_all_idle_cpus - break all cpus out of idle
947 : * wake_up_all_idle_cpus try to break all cpus which is in idle state even
948 : * including idle polling cpus, for non-idle cpus, we will do nothing
949 : * for them.
950 : */
951 0 : void wake_up_all_idle_cpus(void)
952 : {
953 0 : int cpu;
954 :
955 0 : preempt_disable();
956 0 : for_each_online_cpu(cpu) {
957 0 : if (cpu == smp_processor_id())
958 0 : continue;
959 :
960 0 : wake_up_if_idle(cpu);
961 : }
962 0 : preempt_enable();
963 0 : }
964 : EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
965 :
966 : /**
967 : * smp_call_on_cpu - Call a function on a specific cpu
968 : *
969 : * Used to call a function on a specific cpu and wait for it to return.
970 : * Optionally make sure the call is done on a specified physical cpu via vcpu
971 : * pinning in order to support virtualized environments.
972 : */
973 : struct smp_call_on_cpu_struct {
974 : struct work_struct work;
975 : struct completion done;
976 : int (*func)(void *);
977 : void *data;
978 : int ret;
979 : int cpu;
980 : };
981 :
982 0 : static void smp_call_on_cpu_callback(struct work_struct *work)
983 : {
984 0 : struct smp_call_on_cpu_struct *sscs;
985 :
986 0 : sscs = container_of(work, struct smp_call_on_cpu_struct, work);
987 0 : if (sscs->cpu >= 0)
988 0 : hypervisor_pin_vcpu(sscs->cpu);
989 0 : sscs->ret = sscs->func(sscs->data);
990 0 : if (sscs->cpu >= 0)
991 0 : hypervisor_pin_vcpu(-1);
992 :
993 0 : complete(&sscs->done);
994 0 : }
995 :
996 0 : int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
997 : {
998 0 : struct smp_call_on_cpu_struct sscs = {
999 0 : .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
1000 : .func = func,
1001 : .data = par,
1002 0 : .cpu = phys ? cpu : -1,
1003 : };
1004 :
1005 0 : INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
1006 :
1007 0 : if (cpu >= nr_cpu_ids || !cpu_online(cpu))
1008 0 : return -ENXIO;
1009 :
1010 0 : queue_work_on(cpu, system_wq, &sscs.work);
1011 0 : wait_for_completion(&sscs.done);
1012 :
1013 0 : return sscs.ret;
1014 : }
1015 : EXPORT_SYMBOL_GPL(smp_call_on_cpu);
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