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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 : :
26 : : enum {
27 : : CSD_FLAG_LOCK = 0x01,
28 : : CSD_FLAG_SYNCHRONOUS = 0x02,
29 : : };
30 : :
31 : : struct call_function_data {
32 : : call_single_data_t __percpu *csd;
33 : : cpumask_var_t cpumask;
34 : : cpumask_var_t cpumask_ipi;
35 : : };
36 : :
37 : : static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data);
38 : :
39 : : static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
40 : :
41 : : static void flush_smp_call_function_queue(bool warn_cpu_offline);
42 : :
43 : 828 : int smpcfd_prepare_cpu(unsigned int cpu)
44 : : {
45 : 828 : 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 : 828 : cfd->csd = alloc_percpu(call_single_data_t);
56 [ + - ]: 828 : if (!cfd->csd) {
57 : : free_cpumask_var(cfd->cpumask);
58 : : free_cpumask_var(cfd->cpumask_ipi);
59 : : return -ENOMEM;
60 : : }
61 : :
62 : 828 : return 0;
63 : : }
64 : :
65 : 0 : int smpcfd_dead_cpu(unsigned int cpu)
66 : : {
67 : 0 : 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 : 0 : free_percpu(cfd->csd);
72 : 0 : return 0;
73 : : }
74 : :
75 : 0 : int 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 : 0 : flush_smp_call_function_queue(false);
87 : 0 : return 0;
88 : : }
89 : :
90 : 207 : void __init call_function_init(void)
91 : : {
92 : : int i;
93 : :
94 [ + + ]: 1242 : for_each_possible_cpu(i)
95 : 828 : init_llist_head(&per_cpu(call_single_queue, i));
96 : :
97 : 207 : smpcfd_prepare_cpu(smp_processor_id());
98 : 207 : }
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 : : */
107 : : static __always_inline void csd_lock_wait(call_single_data_t *csd)
108 : : {
109 [ - + + + : 6995163 : smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
# # + + +
+ ]
110 : : }
111 : :
112 : : static __always_inline void csd_lock(call_single_data_t *csd)
113 : : {
114 : : csd_lock_wait(csd);
115 : 7496 : 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 : 7496 : smp_wmb();
123 : : }
124 : :
125 : : static __always_inline void csd_unlock(call_single_data_t *csd)
126 : : {
127 [ - + - + : 724448 : WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
- + # # ]
128 : :
129 : : /*
130 : : * ensure we're all done before releasing data:
131 : : */
132 : 724448 : smp_store_release(&csd->flags, 0);
133 : : }
134 : :
135 : : static 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 : : */
142 : 719577 : static int generic_exec_single(int cpu, call_single_data_t *csd,
143 : : smp_call_func_t func, void *info)
144 : : {
145 [ + + ]: 1439154 : 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 : 399 : local_irq_save(flags);
154 : 399 : func(info);
155 [ - + ]: 399 : local_irq_restore(flags);
156 : : return 0;
157 : : }
158 : :
159 : :
160 [ + - - + ]: 1438356 : if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
161 : : csd_unlock(csd);
162 : 0 : return -ENXIO;
163 : : }
164 : :
165 : 719178 : csd->func = func;
166 : 719178 : 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 [ + + ]: 1438356 : if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
180 : 719176 : 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 : : */
191 : 724026 : void generic_smp_call_function_single_interrupt(void)
192 : : {
193 : 724026 : flush_smp_call_function_queue(true);
194 : 724032 : }
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 : : */
210 : 723256 : static 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 : 1446512 : head = this_cpu_ptr(&call_single_queue);
220 : : entry = llist_del_all(head);
221 : 723152 : entry = llist_reverse_order(entry);
222 : :
223 : : /* There shouldn't be any pending callbacks on an offline CPU. */
224 [ + + + - : 2167157 : if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
- + # # -
+ # # ]
225 : : !warned && !llist_empty(head))) {
226 : 0 : warned = true;
227 : 0 : 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 [ # # ]: 0 : llist_for_each_entry(csd, entry, llist)
234 : 0 : pr_warn("IPI callback %pS sent to offline CPU\n",
235 : : csd->func);
236 : : }
237 : :
238 [ + + ]: 2171002 : llist_for_each_entry_safe(csd, csd_next, entry, llist) {
239 : 723391 : smp_call_func_t func = csd->func;
240 : 723391 : void *info = csd->info;
241 : :
242 : : /* Do we wait until *after* callback? */
243 [ + + ]: 723391 : if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
244 : 4479 : func(info);
245 : : csd_unlock(csd);
246 : : } else {
247 : : csd_unlock(csd);
248 : 718912 : 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 : 724012 : irq_work_run();
259 : 723739 : }
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 : : */
269 : 3152 : int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
270 : : int wait)
271 : : {
272 : : call_single_data_t *csd;
273 : 3152 : 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 : 6304 : 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 [ + - - + : 6304 : 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 [ - + # # ]: 3152 : WARN_ON_ONCE(!in_task());
301 : :
302 : : csd = &csd_stack;
303 [ + + ]: 3152 : if (!wait) {
304 : 4974 : csd = this_cpu_ptr(&csd_data);
305 : : csd_lock(csd);
306 : : }
307 : :
308 : 3152 : err = generic_exec_single(cpu, csd, func, info);
309 : :
310 [ + + ]: 3152 : if (wait)
311 : : csd_lock_wait(csd);
312 : :
313 : 3152 : put_cpu();
314 : :
315 : 3152 : return err;
316 : : }
317 : : EXPORT_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 : : */
335 : 716425 : int smp_call_function_single_async(int cpu, call_single_data_t *csd)
336 : : {
337 : : int err = 0;
338 : :
339 : 716425 : preempt_disable();
340 : :
341 : : /* We could deadlock if we have to wait here with interrupts disabled! */
342 [ - + # # : 716425 : if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
- + ]
343 : : csd_lock_wait(csd);
344 : :
345 : 716425 : csd->flags = CSD_FLAG_LOCK;
346 : 716425 : smp_wmb();
347 : :
348 : 716425 : err = generic_exec_single(cpu, csd, csd->func, csd->info);
349 : 716425 : preempt_enable();
350 : :
351 : 716424 : return err;
352 : : }
353 : : EXPORT_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 : : */
369 : 207 : int 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 : 414 : cpu = get_cpu();
378 [ - + ]: 414 : 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 [ # # ]: 0 : for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
384 : 0 : cpu = cpumask_next_and(cpu, nodemask, mask)) {
385 [ # # ]: 0 : if (cpu_online(cpu))
386 : : goto call;
387 : : }
388 : :
389 : : /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
390 : 0 : cpu = cpumask_any_and(mask, cpu_online_mask);
391 : : call:
392 : 207 : ret = smp_call_function_single(cpu, func, info, wait);
393 : 207 : put_cpu();
394 : 207 : return ret;
395 : : }
396 : : EXPORT_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 : : */
412 : 8901 : void 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 : 8901 : 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 [ + - - + : 17802 : 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 [ - + # # ]: 8901 : WARN_ON_ONCE(!in_task());
434 : :
435 : : /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
436 : 8901 : cpu = cpumask_first_and(mask, cpu_online_mask);
437 [ + + ]: 8901 : if (cpu == this_cpu)
438 : 859 : cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
439 : :
440 : : /* No online cpus? We're done. */
441 [ + + ]: 8901 : if (cpu >= nr_cpu_ids)
442 : : return;
443 : :
444 : : /* Do we have another CPU which isn't us? */
445 : 1871 : next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
446 [ + + ]: 1871 : if (next_cpu == this_cpu)
447 : 455 : next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
448 : :
449 : : /* Fastpath: do that cpu by itself. */
450 [ + + ]: 1871 : if (next_cpu >= nr_cpu_ids) {
451 : 142 : smp_call_function_single(cpu, func, info, wait);
452 : 142 : return;
453 : : }
454 : :
455 : 3458 : 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 [ + - ]: 1729 : if (unlikely(!cpumask_weight(cfd->cpumask)))
462 : : return;
463 : :
464 : : cpumask_clear(cfd->cpumask_ipi);
465 [ + + ]: 8467 : for_each_cpu(cpu, cfd->cpumask) {
466 : 5009 : call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
467 : :
468 : : csd_lock(csd);
469 [ + - ]: 5009 : if (wait)
470 : 5009 : csd->flags |= CSD_FLAG_SYNCHRONOUS;
471 : 5009 : csd->func = func;
472 : 5009 : csd->info = info;
473 [ + + ]: 10018 : 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 : 1729 : arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
479 : :
480 [ + - ]: 1729 : if (wait) {
481 [ + + ]: 6738 : for_each_cpu(cpu, cfd->cpumask) {
482 : : call_single_data_t *csd;
483 : :
484 : 5009 : csd = per_cpu_ptr(cfd->csd, cpu);
485 : : csd_lock_wait(csd);
486 : : }
487 : : }
488 : : }
489 : : EXPORT_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 : : */
506 : 0 : void smp_call_function(smp_call_func_t func, void *info, int wait)
507 : : {
508 : 828 : preempt_disable();
509 : 828 : smp_call_function_many(cpu_online_mask, func, info, wait);
510 : 828 : preempt_enable();
511 : 0 : }
512 : : EXPORT_SYMBOL(smp_call_function);
513 : :
514 : : /* Setup configured maximum number of CPUs to activate */
515 : : unsigned int setup_max_cpus = NR_CPUS;
516 : : EXPORT_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 : :
530 : 0 : void __weak arch_disable_smp_support(void) { }
531 : :
532 : 0 : static int __init nosmp(char *str)
533 : : {
534 : 0 : setup_max_cpus = 0;
535 : 0 : arch_disable_smp_support();
536 : :
537 : 0 : return 0;
538 : : }
539 : :
540 : : early_param("nosmp", nosmp);
541 : :
542 : : /* this is hard limit */
543 : 0 : static int __init nrcpus(char *str)
544 : : {
545 : : int nr_cpus;
546 : :
547 : 0 : get_option(&str, &nr_cpus);
548 [ # # # # ]: 0 : if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
549 : 0 : nr_cpu_ids = nr_cpus;
550 : :
551 : 0 : return 0;
552 : : }
553 : :
554 : : early_param("nr_cpus", nrcpus);
555 : :
556 : 0 : static int __init maxcpus(char *str)
557 : : {
558 : 0 : get_option(&str, &setup_max_cpus);
559 [ # # ]: 0 : if (setup_max_cpus == 0)
560 : 0 : arch_disable_smp_support();
561 : :
562 : 0 : return 0;
563 : : }
564 : :
565 : : early_param("maxcpus", maxcpus);
566 : :
567 : : /* Setup number of possible processor ids */
568 : : unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
569 : : EXPORT_SYMBOL(nr_cpu_ids);
570 : :
571 : : /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
572 : 207 : void __init setup_nr_cpu_ids(void)
573 : : {
574 : 207 : nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
575 : 207 : }
576 : :
577 : : /* Called by boot processor to activate the rest. */
578 : 207 : void __init smp_init(void)
579 : : {
580 : : int num_nodes, num_cpus;
581 : : unsigned int cpu;
582 : :
583 : 207 : idle_threads_init();
584 : 207 : cpuhp_threads_init();
585 : :
586 : 207 : pr_info("Bringing up secondary CPUs ...\n");
587 : :
588 : : /* FIXME: This should be done in userspace --RR */
589 [ + + ]: 1242 : for_each_present_cpu(cpu) {
590 [ + - ]: 828 : if (num_online_cpus() >= setup_max_cpus)
591 : : break;
592 [ + + ]: 1656 : if (!cpu_online(cpu))
593 : 621 : cpu_up(cpu);
594 : : }
595 : :
596 : : num_nodes = num_online_nodes();
597 : 207 : num_cpus = num_online_cpus();
598 [ - + ]: 207 : 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 : 207 : smp_cpus_done(setup_max_cpus);
604 : 207 : }
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 : : */
611 : 828 : void on_each_cpu(void (*func) (void *info), void *info, int wait)
612 : : {
613 : : unsigned long flags;
614 : :
615 : 828 : preempt_disable();
616 : : smp_call_function(func, info, wait);
617 : 828 : local_irq_save(flags);
618 : 828 : func(info);
619 [ - + ]: 828 : local_irq_restore(flags);
620 : 828 : preempt_enable();
621 : 828 : }
622 : : EXPORT_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 : : */
640 : 8073 : void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
641 : : void *info, bool wait)
642 : : {
643 : 16146 : int cpu = get_cpu();
644 : :
645 : 8073 : smp_call_function_many(mask, func, info, wait);
646 [ + + ]: 8073 : if (cpumask_test_cpu(cpu, mask)) {
647 : : unsigned long flags;
648 : 1203 : local_irq_save(flags);
649 : 1203 : func(info);
650 [ - + ]: 1203 : local_irq_restore(flags);
651 : : }
652 : 8073 : put_cpu();
653 : 8073 : }
654 : : EXPORT_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 : : */
683 : 8073 : void 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 [ + - ]: 8073 : might_sleep_if(gfpflags_allow_blocking(gfp_flags));
691 : :
692 : : if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
693 : 8073 : preempt_disable();
694 [ + + ]: 48438 : for_each_cpu(cpu, mask)
695 [ + + ]: 32292 : if (cond_func(cpu, info))
696 : : __cpumask_set_cpu(cpu, cpus);
697 : 8073 : on_each_cpu_mask(cpus, func, info, wait);
698 : 8073 : 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 : 8073 : }
715 : : EXPORT_SYMBOL(on_each_cpu_cond_mask);
716 : :
717 : 8073 : void 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 : 8073 : on_each_cpu_cond_mask(cond_func, func, info, wait, gfp_flags,
722 : : cpu_online_mask);
723 : 8073 : }
724 : : EXPORT_SYMBOL(on_each_cpu_cond);
725 : :
726 : 0 : static void do_nothing(void *unused)
727 : : {
728 : 0 : }
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 : : */
741 : 0 : void kick_all_cpus_sync(void)
742 : : {
743 : : /* Make sure the change is visible before we kick the cpus */
744 : 0 : smp_mb();
745 : : smp_call_function(do_nothing, NULL, 1);
746 : 0 : }
747 : : EXPORT_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 : : */
755 : 0 : void wake_up_all_idle_cpus(void)
756 : : {
757 : : int cpu;
758 : :
759 : 0 : preempt_disable();
760 [ # # ]: 0 : for_each_online_cpu(cpu) {
761 [ # # ]: 0 : if (cpu == smp_processor_id())
762 : 0 : continue;
763 : :
764 : 0 : wake_up_if_idle(cpu);
765 : : }
766 : 0 : preempt_enable();
767 : 0 : }
768 : : EXPORT_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 : : */
777 : : struct 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 : :
786 : 0 : static 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 : 0 : sscs->ret = sscs->func(sscs->data);
794 : : if (sscs->cpu >= 0)
795 : : hypervisor_pin_vcpu(-1);
796 : :
797 : 0 : complete(&sscs->done);
798 : 0 : }
799 : :
800 : 0 : int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
801 : : {
802 [ # # ]: 0 : 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 : 0 : INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
810 : :
811 [ # # # # ]: 0 : if (cpu >= nr_cpu_ids || !cpu_online(cpu))
812 : : return -ENXIO;
813 : :
814 : 0 : queue_work_on(cpu, system_wq, &sscs.work);
815 : 0 : wait_for_completion(&sscs.done);
816 : :
817 : 0 : return sscs.ret;
818 : : }
819 : : EXPORT_SYMBOL_GPL(smp_call_on_cpu);
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