Branch data 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/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 : 30 : int smpcfd_prepare_cpu(unsigned int cpu)
44 : : {
45 : 30 : struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
46 : :
47 : 30 : if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
48 : : cpu_to_node(cpu)))
49 : : return -ENOMEM;
50 : 30 : 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 : 30 : cfd->csd = alloc_percpu(call_single_data_t);
56 [ - + ]: 30 : if (!cfd->csd) {
57 : 0 : free_cpumask_var(cfd->cpumask);
58 : 0 : free_cpumask_var(cfd->cpumask_ipi);
59 : 0 : return -ENOMEM;
60 : : }
61 : :
62 : : 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 : 0 : free_cpumask_var(cfd->cpumask);
70 : 0 : 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 : 30 : void __init call_function_init(void)
91 : : {
92 : 30 : int i;
93 : :
94 [ + + ]: 60 : for_each_possible_cpu(i)
95 : 30 : init_llist_head(&per_cpu(call_single_queue, i));
96 : :
97 : 30 : smpcfd_prepare_cpu(smp_processor_id());
98 : 30 : }
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 : 0 : static __always_inline void csd_lock_wait(call_single_data_t *csd)
108 : : {
109 [ - - - - : 86 : smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
- - - - -
+ ]
110 : 86 : }
111 : :
112 : 0 : static __always_inline void csd_lock(call_single_data_t *csd)
113 : : {
114 : 0 : csd_lock_wait(csd);
115 : 0 : 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 : 0 : smp_wmb();
123 : 0 : }
124 : :
125 : 86 : static __always_inline void csd_unlock(call_single_data_t *csd)
126 : : {
127 : 0 : WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
128 : :
129 : : /*
130 : : * ensure we're all done before releasing data:
131 : : */
132 : 86 : smp_store_release(&csd->flags, 0);
133 : 0 : }
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 : 86 : static int generic_exec_single(int cpu, call_single_data_t *csd,
143 : : smp_call_func_t func, void *info)
144 : : {
145 [ + - ]: 86 : if (cpu == smp_processor_id()) {
146 : 86 : 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 [ - + ]: 86 : csd_unlock(csd);
153 : 86 : local_irq_save(flags);
154 : 86 : func(info);
155 : 86 : local_irq_restore(flags);
156 : 86 : return 0;
157 : : }
158 : :
159 : :
160 [ # # # # ]: 0 : if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
161 [ # # ]: 0 : csd_unlock(csd);
162 : 0 : return -ENXIO;
163 : : }
164 : :
165 : 0 : csd->func = func;
166 : 0 : 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 [ # # ]: 0 : if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
180 : 0 : 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 : 0 : void generic_smp_call_function_single_interrupt(void)
192 : : {
193 : 0 : flush_smp_call_function_queue(true);
194 : 0 : }
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 : 0 : static void flush_smp_call_function_queue(bool warn_cpu_offline)
211 : : {
212 : 0 : struct llist_head *head;
213 : 0 : struct llist_node *entry;
214 : 0 : call_single_data_t *csd, *csd_next;
215 : 0 : static bool warned;
216 : :
217 : 0 : lockdep_assert_irqs_disabled();
218 : :
219 : 0 : head = this_cpu_ptr(&call_single_queue);
220 : 0 : entry = llist_del_all(head);
221 : 0 : entry = llist_reverse_order(entry);
222 : :
223 : : /* There shouldn't be any pending callbacks on an offline CPU. */
224 [ # # # # : 0 : 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 [ # # ]: 0 : llist_for_each_entry_safe(csd, csd_next, entry, llist) {
239 : 0 : smp_call_func_t func = csd->func;
240 : 0 : void *info = csd->info;
241 : :
242 : : /* Do we wait until *after* callback? */
243 [ # # ]: 0 : if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
244 : 0 : func(info);
245 [ # # ]: 0 : csd_unlock(csd);
246 : : } else {
247 [ # # ]: 0 : csd_unlock(csd);
248 : 0 : 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 : 0 : irq_work_run();
259 : 0 : }
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 : 86 : int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
270 : : int wait)
271 : : {
272 : 86 : call_single_data_t *csd;
273 : 86 : call_single_data_t csd_stack = {
274 : : .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS,
275 : : };
276 : 86 : int this_cpu;
277 : 86 : int err;
278 : :
279 : : /*
280 : : * prevent preemption and reschedule on another processor,
281 : : * as well as CPU removal
282 : : */
283 : 86 : 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 [ + - - + : 86 : 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 [ - + ]: 86 : WARN_ON_ONCE(!in_task());
301 : :
302 : 86 : csd = &csd_stack;
303 [ - + ]: 86 : if (!wait) {
304 : 0 : csd = this_cpu_ptr(&csd_data);
305 : 0 : csd_lock(csd);
306 : : }
307 : :
308 : 86 : err = generic_exec_single(cpu, csd, func, info);
309 : :
310 [ + - ]: 86 : if (wait)
311 : : csd_lock_wait(csd);
312 : :
313 : 86 : put_cpu();
314 : :
315 : 86 : 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 : 0 : int smp_call_function_single_async(int cpu, call_single_data_t *csd)
336 : : {
337 : 0 : int err = 0;
338 : :
339 : 0 : preempt_disable();
340 : :
341 : : /* We could deadlock if we have to wait here with interrupts disabled! */
342 [ # # # # ]: 0 : if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
343 : : csd_lock_wait(csd);
344 : :
345 : 0 : csd->flags = CSD_FLAG_LOCK;
346 : 0 : smp_wmb();
347 : :
348 : 0 : err = generic_exec_single(cpu, csd, csd->func, csd->info);
349 : 0 : preempt_enable();
350 : :
351 : 0 : 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 : 0 : int smp_call_function_any(const struct cpumask *mask,
370 : : smp_call_func_t func, void *info, int wait)
371 : : {
372 : 0 : unsigned int cpu;
373 : 0 : const struct cpumask *nodemask;
374 : 0 : int ret;
375 : :
376 : : /* Try for same CPU (cheapest) */
377 : 0 : cpu = get_cpu();
378 [ # # ]: 0 : if (cpumask_test_cpu(cpu, mask))
379 : 0 : goto call;
380 : :
381 : : /* Try for same node. */
382 : 0 : 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 : 0 : 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 : 0 : call:
392 : 0 : ret = smp_call_function_single(cpu, func, info, wait);
393 : 0 : put_cpu();
394 : 0 : return ret;
395 : : }
396 : : EXPORT_SYMBOL_GPL(smp_call_function_any);
397 : :
398 : 5797 : static void smp_call_function_many_cond(const struct cpumask *mask,
399 : : smp_call_func_t func, void *info,
400 : : bool wait, smp_cond_func_t cond_func)
401 : : {
402 : 5797 : struct call_function_data *cfd;
403 : 5797 : int cpu, next_cpu, this_cpu = smp_processor_id();
404 : :
405 : : /*
406 : : * Can deadlock when called with interrupts disabled.
407 : : * We allow cpu's that are not yet online though, as no one else can
408 : : * send smp call function interrupt to this cpu and as such deadlocks
409 : : * can't happen.
410 : : */
411 [ + - - + : 5797 : WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
- - - - -
+ ]
412 : : && !oops_in_progress && !early_boot_irqs_disabled);
413 : :
414 : : /*
415 : : * When @wait we can deadlock when we interrupt between llist_add() and
416 : : * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
417 : : * csd_lock() on because the interrupt context uses the same csd
418 : : * storage.
419 : : */
420 [ - + ]: 5797 : WARN_ON_ONCE(!in_task());
421 : :
422 : : /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
423 : 5797 : cpu = cpumask_first_and(mask, cpu_online_mask);
424 [ + - ]: 5797 : if (cpu == this_cpu)
425 : 5797 : cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
426 : :
427 : : /* No online cpus? We're done. */
428 [ - + ]: 5797 : if (cpu >= nr_cpu_ids)
429 : : return;
430 : :
431 : : /* Do we have another CPU which isn't us? */
432 : 0 : next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
433 [ # # ]: 0 : if (next_cpu == this_cpu)
434 : 0 : next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
435 : :
436 : : /* Fastpath: do that cpu by itself. */
437 [ # # ]: 0 : if (next_cpu >= nr_cpu_ids) {
438 [ # # # # ]: 0 : if (!cond_func || cond_func(cpu, info))
439 : 0 : smp_call_function_single(cpu, func, info, wait);
440 : 0 : return;
441 : : }
442 : :
443 : 0 : cfd = this_cpu_ptr(&cfd_data);
444 : :
445 : 0 : cpumask_and(cfd->cpumask, mask, cpu_online_mask);
446 : 0 : __cpumask_clear_cpu(this_cpu, cfd->cpumask);
447 : :
448 : : /* Some callers race with other cpus changing the passed mask */
449 [ # # ]: 0 : if (unlikely(!cpumask_weight(cfd->cpumask)))
450 : : return;
451 : :
452 : 0 : cpumask_clear(cfd->cpumask_ipi);
453 [ # # ]: 0 : for_each_cpu(cpu, cfd->cpumask) {
454 : 0 : call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
455 : :
456 [ # # # # ]: 0 : if (cond_func && !cond_func(cpu, info))
457 : 0 : continue;
458 : :
459 : : csd_lock(csd);
460 [ # # ]: 0 : if (wait)
461 : 0 : csd->flags |= CSD_FLAG_SYNCHRONOUS;
462 : 0 : csd->func = func;
463 : 0 : csd->info = info;
464 [ # # ]: 0 : if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
465 : 0 : __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
466 : : }
467 : :
468 : : /* Send a message to all CPUs in the map */
469 : 0 : arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
470 : :
471 [ # # ]: 0 : if (wait) {
472 [ # # ]: 0 : for_each_cpu(cpu, cfd->cpumask) {
473 : 0 : call_single_data_t *csd;
474 : :
475 : 0 : csd = per_cpu_ptr(cfd->csd, cpu);
476 : 0 : csd_lock_wait(csd);
477 : : }
478 : : }
479 : : }
480 : :
481 : : /**
482 : : * smp_call_function_many(): Run a function on a set of other CPUs.
483 : : * @mask: The set of cpus to run on (only runs on online subset).
484 : : * @func: The function to run. This must be fast and non-blocking.
485 : : * @info: An arbitrary pointer to pass to the function.
486 : : * @wait: If true, wait (atomically) until function has completed
487 : : * on other CPUs.
488 : : *
489 : : * If @wait is true, then returns once @func has returned.
490 : : *
491 : : * You must not call this function with disabled interrupts or from a
492 : : * hardware interrupt handler or from a bottom half handler. Preemption
493 : : * must be disabled when calling this function.
494 : : */
495 : 5437 : void smp_call_function_many(const struct cpumask *mask,
496 : : smp_call_func_t func, void *info, bool wait)
497 : : {
498 : 0 : smp_call_function_many_cond(mask, func, info, wait, NULL);
499 : 0 : }
500 : : EXPORT_SYMBOL(smp_call_function_many);
501 : :
502 : : /**
503 : : * smp_call_function(): Run a function on all other CPUs.
504 : : * @func: The function to run. This must be fast and non-blocking.
505 : : * @info: An arbitrary pointer to pass to the function.
506 : : * @wait: If true, wait (atomically) until function has completed
507 : : * on other CPUs.
508 : : *
509 : : * Returns 0.
510 : : *
511 : : * If @wait is true, then returns once @func has returned; otherwise
512 : : * it returns just before the target cpu calls @func.
513 : : *
514 : : * You must not call this function with disabled interrupts or from a
515 : : * hardware interrupt handler or from a bottom half handler.
516 : : */
517 : 5437 : void smp_call_function(smp_call_func_t func, void *info, int wait)
518 : : {
519 : 0 : preempt_disable();
520 : 5437 : smp_call_function_many(cpu_online_mask, func, info, wait);
521 : 5437 : preempt_enable();
522 : 0 : }
523 : : EXPORT_SYMBOL(smp_call_function);
524 : :
525 : : /* Setup configured maximum number of CPUs to activate */
526 : : unsigned int setup_max_cpus = NR_CPUS;
527 : : EXPORT_SYMBOL(setup_max_cpus);
528 : :
529 : :
530 : : /*
531 : : * Setup routine for controlling SMP activation
532 : : *
533 : : * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
534 : : * activation entirely (the MPS table probe still happens, though).
535 : : *
536 : : * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
537 : : * greater than 0, limits the maximum number of CPUs activated in
538 : : * SMP mode to <NUM>.
539 : : */
540 : :
541 : 0 : void __weak arch_disable_smp_support(void) { }
542 : :
543 : 0 : static int __init nosmp(char *str)
544 : : {
545 : 0 : setup_max_cpus = 0;
546 : 0 : arch_disable_smp_support();
547 : :
548 : 0 : return 0;
549 : : }
550 : :
551 : : early_param("nosmp", nosmp);
552 : :
553 : : /* this is hard limit */
554 : 0 : static int __init nrcpus(char *str)
555 : : {
556 : 0 : int nr_cpus;
557 : :
558 : 0 : get_option(&str, &nr_cpus);
559 [ # # # # ]: 0 : if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
560 : 0 : nr_cpu_ids = nr_cpus;
561 : :
562 : 0 : return 0;
563 : : }
564 : :
565 : : early_param("nr_cpus", nrcpus);
566 : :
567 : 0 : static int __init maxcpus(char *str)
568 : : {
569 : 0 : get_option(&str, &setup_max_cpus);
570 [ # # ]: 0 : if (setup_max_cpus == 0)
571 : 0 : arch_disable_smp_support();
572 : :
573 : 0 : return 0;
574 : : }
575 : :
576 : : early_param("maxcpus", maxcpus);
577 : :
578 : : /* Setup number of possible processor ids */
579 : : unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
580 : : EXPORT_SYMBOL(nr_cpu_ids);
581 : :
582 : : /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
583 : 30 : void __init setup_nr_cpu_ids(void)
584 : : {
585 : 30 : nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
586 : 30 : }
587 : :
588 : : /* Called by boot processor to activate the rest. */
589 : 30 : void __init smp_init(void)
590 : : {
591 : 30 : int num_nodes, num_cpus;
592 : 30 : unsigned int cpu;
593 : :
594 : 30 : idle_threads_init();
595 : 30 : cpuhp_threads_init();
596 : :
597 : 30 : pr_info("Bringing up secondary CPUs ...\n");
598 : :
599 : : /* FIXME: This should be done in userspace --RR */
600 [ + + ]: 90 : for_each_present_cpu(cpu) {
601 [ + - ]: 30 : if (num_online_cpus() >= setup_max_cpus)
602 : : break;
603 [ - + ]: 30 : if (!cpu_online(cpu))
604 : 0 : cpu_up(cpu);
605 : : }
606 : :
607 : 30 : num_nodes = num_online_nodes();
608 : 30 : num_cpus = num_online_cpus();
609 [ + - + - ]: 90 : pr_info("Brought up %d node%s, %d CPU%s\n",
610 : : num_nodes, (num_nodes > 1 ? "s" : ""),
611 : : num_cpus, (num_cpus > 1 ? "s" : ""));
612 : :
613 : : /* Any cleanup work */
614 : 30 : smp_cpus_done(setup_max_cpus);
615 : 30 : }
616 : :
617 : : /*
618 : : * Call a function on all processors. May be used during early boot while
619 : : * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
620 : : * of local_irq_disable/enable().
621 : : */
622 : 5437 : void on_each_cpu(void (*func) (void *info), void *info, int wait)
623 : : {
624 : 5437 : unsigned long flags;
625 : :
626 : 5437 : preempt_disable();
627 : 5437 : smp_call_function(func, info, wait);
628 : 5437 : local_irq_save(flags);
629 : 5437 : func(info);
630 : 5437 : local_irq_restore(flags);
631 : 5437 : preempt_enable();
632 : 5437 : }
633 : : EXPORT_SYMBOL(on_each_cpu);
634 : :
635 : : /**
636 : : * on_each_cpu_mask(): Run a function on processors specified by
637 : : * cpumask, which may include the local processor.
638 : : * @mask: The set of cpus to run on (only runs on online subset).
639 : : * @func: The function to run. This must be fast and non-blocking.
640 : : * @info: An arbitrary pointer to pass to the function.
641 : : * @wait: If true, wait (atomically) until function has completed
642 : : * on other CPUs.
643 : : *
644 : : * If @wait is true, then returns once @func has returned.
645 : : *
646 : : * You must not call this function with disabled interrupts or from a
647 : : * hardware interrupt handler or from a bottom half handler. The
648 : : * exception is that it may be used during early boot while
649 : : * early_boot_irqs_disabled is set.
650 : : */
651 : 0 : void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
652 : : void *info, bool wait)
653 : : {
654 : 0 : int cpu = get_cpu();
655 : :
656 : 0 : smp_call_function_many(mask, func, info, wait);
657 [ # # ]: 0 : if (cpumask_test_cpu(cpu, mask)) {
658 : 0 : unsigned long flags;
659 : 0 : local_irq_save(flags);
660 : 0 : func(info);
661 : 0 : local_irq_restore(flags);
662 : : }
663 : 0 : put_cpu();
664 : 0 : }
665 : : EXPORT_SYMBOL(on_each_cpu_mask);
666 : :
667 : : /*
668 : : * on_each_cpu_cond(): Call a function on each processor for which
669 : : * the supplied function cond_func returns true, optionally waiting
670 : : * for all the required CPUs to finish. This may include the local
671 : : * processor.
672 : : * @cond_func: A callback function that is passed a cpu id and
673 : : * the the info parameter. The function is called
674 : : * with preemption disabled. The function should
675 : : * return a blooean value indicating whether to IPI
676 : : * the specified CPU.
677 : : * @func: The function to run on all applicable CPUs.
678 : : * This must be fast and non-blocking.
679 : : * @info: An arbitrary pointer to pass to both functions.
680 : : * @wait: If true, wait (atomically) until function has
681 : : * completed on other CPUs.
682 : : *
683 : : * Preemption is disabled to protect against CPUs going offline but not online.
684 : : * CPUs going online during the call will not be seen or sent an IPI.
685 : : *
686 : : * You must not call this function with disabled interrupts or
687 : : * from a hardware interrupt handler or from a bottom half handler.
688 : : */
689 : 360 : void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
690 : : void *info, bool wait, const struct cpumask *mask)
691 : : {
692 : 360 : int cpu = get_cpu();
693 : :
694 : 360 : smp_call_function_many_cond(mask, func, info, wait, cond_func);
695 [ + - + + ]: 360 : if (cpumask_test_cpu(cpu, mask) && cond_func(cpu, info)) {
696 : 300 : unsigned long flags;
697 : :
698 : 300 : local_irq_save(flags);
699 : 300 : func(info);
700 : 300 : local_irq_restore(flags);
701 : : }
702 : 360 : put_cpu();
703 : 360 : }
704 : : EXPORT_SYMBOL(on_each_cpu_cond_mask);
705 : :
706 : 360 : void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
707 : : void *info, bool wait)
708 : : {
709 : 360 : on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
710 : 360 : }
711 : : EXPORT_SYMBOL(on_each_cpu_cond);
712 : :
713 : 0 : static void do_nothing(void *unused)
714 : : {
715 : 0 : }
716 : :
717 : : /**
718 : : * kick_all_cpus_sync - Force all cpus out of idle
719 : : *
720 : : * Used to synchronize the update of pm_idle function pointer. It's
721 : : * called after the pointer is updated and returns after the dummy
722 : : * callback function has been executed on all cpus. The execution of
723 : : * the function can only happen on the remote cpus after they have
724 : : * left the idle function which had been called via pm_idle function
725 : : * pointer. So it's guaranteed that nothing uses the previous pointer
726 : : * anymore.
727 : : */
728 : 0 : void kick_all_cpus_sync(void)
729 : : {
730 : : /* Make sure the change is visible before we kick the cpus */
731 : 0 : smp_mb();
732 : 0 : smp_call_function(do_nothing, NULL, 1);
733 : 0 : }
734 : : EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
735 : :
736 : : /**
737 : : * wake_up_all_idle_cpus - break all cpus out of idle
738 : : * wake_up_all_idle_cpus try to break all cpus which is in idle state even
739 : : * including idle polling cpus, for non-idle cpus, we will do nothing
740 : : * for them.
741 : : */
742 : 0 : void wake_up_all_idle_cpus(void)
743 : : {
744 : 0 : int cpu;
745 : :
746 : 0 : preempt_disable();
747 [ # # ]: 0 : for_each_online_cpu(cpu) {
748 [ # # ]: 0 : if (cpu == smp_processor_id())
749 : 0 : continue;
750 : :
751 : 0 : wake_up_if_idle(cpu);
752 : : }
753 : 0 : preempt_enable();
754 : 0 : }
755 : : EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
756 : :
757 : : /**
758 : : * smp_call_on_cpu - Call a function on a specific cpu
759 : : *
760 : : * Used to call a function on a specific cpu and wait for it to return.
761 : : * Optionally make sure the call is done on a specified physical cpu via vcpu
762 : : * pinning in order to support virtualized environments.
763 : : */
764 : : struct smp_call_on_cpu_struct {
765 : : struct work_struct work;
766 : : struct completion done;
767 : : int (*func)(void *);
768 : : void *data;
769 : : int ret;
770 : : int cpu;
771 : : };
772 : :
773 : 0 : static void smp_call_on_cpu_callback(struct work_struct *work)
774 : : {
775 : 0 : struct smp_call_on_cpu_struct *sscs;
776 : :
777 : 0 : sscs = container_of(work, struct smp_call_on_cpu_struct, work);
778 [ # # ]: 0 : if (sscs->cpu >= 0)
779 : 0 : hypervisor_pin_vcpu(sscs->cpu);
780 : 0 : sscs->ret = sscs->func(sscs->data);
781 [ # # ]: 0 : if (sscs->cpu >= 0)
782 : 0 : hypervisor_pin_vcpu(-1);
783 : :
784 : 0 : complete(&sscs->done);
785 : 0 : }
786 : :
787 : 0 : int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
788 : : {
789 : 0 : struct smp_call_on_cpu_struct sscs = {
790 : 0 : .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
791 : : .func = func,
792 : : .data = par,
793 [ # # ]: 0 : .cpu = phys ? cpu : -1,
794 : : };
795 : :
796 [ # # ]: 0 : INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
797 : :
798 [ # # # # ]: 0 : if (cpu >= nr_cpu_ids || !cpu_online(cpu))
799 : 0 : return -ENXIO;
800 : :
801 : 0 : queue_work_on(cpu, system_wq, &sscs.work);
802 : 0 : wait_for_completion(&sscs.done);
803 : :
804 : 0 : return sscs.ret;
805 : : }
806 : : EXPORT_SYMBOL_GPL(smp_call_on_cpu);
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