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1 | /* | |
2 | * Generic helpers for smp ipi calls | |
3 | * | |
4 | * (C) Jens Axboe <jens.axboe@oracle.com> 2008 | |
5 | */ | |
6 | ||
7 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
8 | ||
9 | #include <linux/irq_work.h> | |
10 | #include <linux/rcupdate.h> | |
11 | #include <linux/rculist.h> | |
12 | #include <linux/kernel.h> | |
13 | #include <linux/export.h> | |
14 | #include <linux/percpu.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/gfp.h> | |
17 | #include <linux/smp.h> | |
18 | #include <linux/cpu.h> | |
19 | #include <linux/sched.h> | |
20 | #include <linux/sched/idle.h> | |
21 | #include <linux/hypervisor.h> | |
22 | ||
23 | #include "smpboot.h" | |
24 | ||
25 | enum { | |
26 | CSD_FLAG_LOCK = 0x01, | |
27 | CSD_FLAG_SYNCHRONOUS = 0x02, | |
28 | }; | |
29 | ||
30 | struct call_function_data { | |
31 | call_single_data_t __percpu *csd; | |
32 | cpumask_var_t cpumask; | |
33 | cpumask_var_t cpumask_ipi; | |
34 | }; | |
35 | ||
36 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data); | |
37 | ||
38 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); | |
39 | ||
40 | static void flush_smp_call_function_queue(bool warn_cpu_offline); | |
41 | ||
42 | int smpcfd_prepare_cpu(unsigned int cpu) | |
43 | { | |
44 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); | |
45 | ||
46 | if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, | |
47 | cpu_to_node(cpu))) | |
48 | return -ENOMEM; | |
49 | if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL, | |
50 | cpu_to_node(cpu))) { | |
51 | free_cpumask_var(cfd->cpumask); | |
52 | return -ENOMEM; | |
53 | } | |
54 | cfd->csd = alloc_percpu(call_single_data_t); | |
55 | if (!cfd->csd) { | |
56 | free_cpumask_var(cfd->cpumask); | |
57 | free_cpumask_var(cfd->cpumask_ipi); | |
58 | return -ENOMEM; | |
59 | } | |
60 | ||
61 | return 0; | |
62 | } | |
63 | ||
64 | int smpcfd_dead_cpu(unsigned int cpu) | |
65 | { | |
66 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); | |
67 | ||
68 | free_cpumask_var(cfd->cpumask); | |
69 | free_cpumask_var(cfd->cpumask_ipi); | |
70 | free_percpu(cfd->csd); | |
71 | return 0; | |
72 | } | |
73 | ||
74 | int smpcfd_dying_cpu(unsigned int cpu) | |
75 | { | |
76 | /* | |
77 | * The IPIs for the smp-call-function callbacks queued by other | |
78 | * CPUs might arrive late, either due to hardware latencies or | |
79 | * because this CPU disabled interrupts (inside stop-machine) | |
80 | * before the IPIs were sent. So flush out any pending callbacks | |
81 | * explicitly (without waiting for the IPIs to arrive), to | |
82 | * ensure that the outgoing CPU doesn't go offline with work | |
83 | * still pending. | |
84 | */ | |
85 | flush_smp_call_function_queue(false); | |
86 | return 0; | |
87 | } | |
88 | ||
89 | void __init call_function_init(void) | |
90 | { | |
91 | int i; | |
92 | ||
93 | for_each_possible_cpu(i) | |
94 | init_llist_head(&per_cpu(call_single_queue, i)); | |
95 | ||
96 | smpcfd_prepare_cpu(smp_processor_id()); | |
97 | } | |
98 | ||
99 | /* | |
100 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources | |
101 | * | |
102 | * For non-synchronous ipi calls the csd can still be in use by the | |
103 | * previous function call. For multi-cpu calls its even more interesting | |
104 | * as we'll have to ensure no other cpu is observing our csd. | |
105 | */ | |
106 | static __always_inline void csd_lock_wait(call_single_data_t *csd) | |
107 | { | |
108 | smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK)); | |
109 | } | |
110 | ||
111 | static __always_inline void csd_lock(call_single_data_t *csd) | |
112 | { | |
113 | csd_lock_wait(csd); | |
114 | csd->flags |= CSD_FLAG_LOCK; | |
115 | ||
116 | /* | |
117 | * prevent CPU from reordering the above assignment | |
118 | * to ->flags with any subsequent assignments to other | |
119 | * fields of the specified call_single_data_t structure: | |
120 | */ | |
121 | smp_wmb(); | |
122 | } | |
123 | ||
124 | static __always_inline void csd_unlock(call_single_data_t *csd) | |
125 | { | |
126 | WARN_ON(!(csd->flags & CSD_FLAG_LOCK)); | |
127 | ||
128 | /* | |
129 | * ensure we're all done before releasing data: | |
130 | */ | |
131 | smp_store_release(&csd->flags, 0); | |
132 | } | |
133 | ||
134 | static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data); | |
135 | ||
136 | /* | |
137 | * Insert a previously allocated call_single_data_t element | |
138 | * for execution on the given CPU. data must already have | |
139 | * ->func, ->info, and ->flags set. | |
140 | */ | |
141 | static int generic_exec_single(int cpu, call_single_data_t *csd, | |
142 | smp_call_func_t func, void *info) | |
143 | { | |
144 | if (cpu == smp_processor_id()) { | |
145 | unsigned long flags; | |
146 | ||
147 | /* | |
148 | * We can unlock early even for the synchronous on-stack case, | |
149 | * since we're doing this from the same CPU.. | |
150 | */ | |
151 | csd_unlock(csd); | |
152 | local_irq_save(flags); | |
153 | func(info); | |
154 | local_irq_restore(flags); | |
155 | return 0; | |
156 | } | |
157 | ||
158 | ||
159 | if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) { | |
160 | csd_unlock(csd); | |
161 | return -ENXIO; | |
162 | } | |
163 | ||
164 | csd->func = func; | |
165 | csd->info = info; | |
166 | ||
167 | /* | |
168 | * The list addition should be visible before sending the IPI | |
169 | * handler locks the list to pull the entry off it because of | |
170 | * normal cache coherency rules implied by spinlocks. | |
171 | * | |
172 | * If IPIs can go out of order to the cache coherency protocol | |
173 | * in an architecture, sufficient synchronisation should be added | |
174 | * to arch code to make it appear to obey cache coherency WRT | |
175 | * locking and barrier primitives. Generic code isn't really | |
176 | * equipped to do the right thing... | |
177 | */ | |
178 | if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) | |
179 | arch_send_call_function_single_ipi(cpu); | |
180 | ||
181 | return 0; | |
182 | } | |
183 | ||
184 | /** | |
185 | * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks | |
186 | * | |
187 | * Invoked by arch to handle an IPI for call function single. | |
188 | * Must be called with interrupts disabled. | |
189 | */ | |
190 | void generic_smp_call_function_single_interrupt(void) | |
191 | { | |
192 | flush_smp_call_function_queue(true); | |
193 | } | |
194 | ||
195 | /** | |
196 | * flush_smp_call_function_queue - Flush pending smp-call-function callbacks | |
197 | * | |
198 | * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an | |
199 | * offline CPU. Skip this check if set to 'false'. | |
200 | * | |
201 | * Flush any pending smp-call-function callbacks queued on this CPU. This is | |
202 | * invoked by the generic IPI handler, as well as by a CPU about to go offline, | |
203 | * to ensure that all pending IPI callbacks are run before it goes completely | |
204 | * offline. | |
205 | * | |
206 | * Loop through the call_single_queue and run all the queued callbacks. | |
207 | * Must be called with interrupts disabled. | |
208 | */ | |
209 | static void flush_smp_call_function_queue(bool warn_cpu_offline) | |
210 | { | |
211 | struct llist_head *head; | |
212 | struct llist_node *entry; | |
213 | call_single_data_t *csd, *csd_next; | |
214 | static bool warned; | |
215 | ||
216 | lockdep_assert_irqs_disabled(); | |
217 | ||
218 | head = this_cpu_ptr(&call_single_queue); | |
219 | entry = llist_del_all(head); | |
220 | entry = llist_reverse_order(entry); | |
221 | ||
222 | /* There shouldn't be any pending callbacks on an offline CPU. */ | |
223 | if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) && | |
224 | !warned && !llist_empty(head))) { | |
225 | warned = true; | |
226 | WARN(1, "IPI on offline CPU %d\n", smp_processor_id()); | |
227 | ||
228 | /* | |
229 | * We don't have to use the _safe() variant here | |
230 | * because we are not invoking the IPI handlers yet. | |
231 | */ | |
232 | llist_for_each_entry(csd, entry, llist) | |
233 | pr_warn("IPI callback %pS sent to offline CPU\n", | |
234 | csd->func); | |
235 | } | |
236 | ||
237 | llist_for_each_entry_safe(csd, csd_next, entry, llist) { | |
238 | smp_call_func_t func = csd->func; | |
239 | void *info = csd->info; | |
240 | ||
241 | /* Do we wait until *after* callback? */ | |
242 | if (csd->flags & CSD_FLAG_SYNCHRONOUS) { | |
243 | func(info); | |
244 | csd_unlock(csd); | |
245 | } else { | |
246 | csd_unlock(csd); | |
247 | func(info); | |
248 | } | |
249 | } | |
250 | ||
251 | /* | |
252 | * Handle irq works queued remotely by irq_work_queue_on(). | |
253 | * Smp functions above are typically synchronous so they | |
254 | * better run first since some other CPUs may be busy waiting | |
255 | * for them. | |
256 | */ | |
257 | irq_work_run(); | |
258 | } | |
259 | ||
260 | /* | |
261 | * smp_call_function_single - Run a function on a specific CPU | |
262 | * @func: The function to run. This must be fast and non-blocking. | |
263 | * @info: An arbitrary pointer to pass to the function. | |
264 | * @wait: If true, wait until function has completed on other CPUs. | |
265 | * | |
266 | * Returns 0 on success, else a negative status code. | |
267 | */ | |
268 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info, | |
269 | int wait) | |
270 | { | |
271 | call_single_data_t *csd; | |
272 | call_single_data_t csd_stack = { | |
273 | .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS, | |
274 | }; | |
275 | int this_cpu; | |
276 | int err; | |
277 | ||
278 | /* | |
279 | * prevent preemption and reschedule on another processor, | |
280 | * as well as CPU removal | |
281 | */ | |
282 | this_cpu = get_cpu(); | |
283 | ||
284 | /* | |
285 | * Can deadlock when called with interrupts disabled. | |
286 | * We allow cpu's that are not yet online though, as no one else can | |
287 | * send smp call function interrupt to this cpu and as such deadlocks | |
288 | * can't happen. | |
289 | */ | |
290 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() | |
291 | && !oops_in_progress); | |
292 | ||
293 | csd = &csd_stack; | |
294 | if (!wait) { | |
295 | csd = this_cpu_ptr(&csd_data); | |
296 | csd_lock(csd); | |
297 | } | |
298 | ||
299 | err = generic_exec_single(cpu, csd, func, info); | |
300 | ||
301 | if (wait) | |
302 | csd_lock_wait(csd); | |
303 | ||
304 | put_cpu(); | |
305 | ||
306 | return err; | |
307 | } | |
308 | EXPORT_SYMBOL(smp_call_function_single); | |
309 | ||
310 | /** | |
311 | * smp_call_function_single_async(): Run an asynchronous function on a | |
312 | * specific CPU. | |
313 | * @cpu: The CPU to run on. | |
314 | * @csd: Pre-allocated and setup data structure | |
315 | * | |
316 | * Like smp_call_function_single(), but the call is asynchonous and | |
317 | * can thus be done from contexts with disabled interrupts. | |
318 | * | |
319 | * The caller passes his own pre-allocated data structure | |
320 | * (ie: embedded in an object) and is responsible for synchronizing it | |
321 | * such that the IPIs performed on the @csd are strictly serialized. | |
322 | * | |
323 | * NOTE: Be careful, there is unfortunately no current debugging facility to | |
324 | * validate the correctness of this serialization. | |
325 | */ | |
326 | int smp_call_function_single_async(int cpu, call_single_data_t *csd) | |
327 | { | |
328 | int err = 0; | |
329 | ||
330 | preempt_disable(); | |
331 | ||
332 | /* We could deadlock if we have to wait here with interrupts disabled! */ | |
333 | if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK)) | |
334 | csd_lock_wait(csd); | |
335 | ||
336 | csd->flags = CSD_FLAG_LOCK; | |
337 | smp_wmb(); | |
338 | ||
339 | err = generic_exec_single(cpu, csd, csd->func, csd->info); | |
340 | preempt_enable(); | |
341 | ||
342 | return err; | |
343 | } | |
344 | EXPORT_SYMBOL_GPL(smp_call_function_single_async); | |
345 | ||
346 | /* | |
347 | * smp_call_function_any - Run a function on any of the given cpus | |
348 | * @mask: The mask of cpus it can run on. | |
349 | * @func: The function to run. This must be fast and non-blocking. | |
350 | * @info: An arbitrary pointer to pass to the function. | |
351 | * @wait: If true, wait until function has completed. | |
352 | * | |
353 | * Returns 0 on success, else a negative status code (if no cpus were online). | |
354 | * | |
355 | * Selection preference: | |
356 | * 1) current cpu if in @mask | |
357 | * 2) any cpu of current node if in @mask | |
358 | * 3) any other online cpu in @mask | |
359 | */ | |
360 | int smp_call_function_any(const struct cpumask *mask, | |
361 | smp_call_func_t func, void *info, int wait) | |
362 | { | |
363 | unsigned int cpu; | |
364 | const struct cpumask *nodemask; | |
365 | int ret; | |
366 | ||
367 | /* Try for same CPU (cheapest) */ | |
368 | cpu = get_cpu(); | |
369 | if (cpumask_test_cpu(cpu, mask)) | |
370 | goto call; | |
371 | ||
372 | /* Try for same node. */ | |
373 | nodemask = cpumask_of_node(cpu_to_node(cpu)); | |
374 | for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids; | |
375 | cpu = cpumask_next_and(cpu, nodemask, mask)) { | |
376 | if (cpu_online(cpu)) | |
377 | goto call; | |
378 | } | |
379 | ||
380 | /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ | |
381 | cpu = cpumask_any_and(mask, cpu_online_mask); | |
382 | call: | |
383 | ret = smp_call_function_single(cpu, func, info, wait); | |
384 | put_cpu(); | |
385 | return ret; | |
386 | } | |
387 | EXPORT_SYMBOL_GPL(smp_call_function_any); | |
388 | ||
389 | /** | |
390 | * smp_call_function_many(): Run a function on a set of other CPUs. | |
391 | * @mask: The set of cpus to run on (only runs on online subset). | |
392 | * @func: The function to run. This must be fast and non-blocking. | |
393 | * @info: An arbitrary pointer to pass to the function. | |
394 | * @wait: If true, wait (atomically) until function has completed | |
395 | * on other CPUs. | |
396 | * | |
397 | * If @wait is true, then returns once @func has returned. | |
398 | * | |
399 | * You must not call this function with disabled interrupts or from a | |
400 | * hardware interrupt handler or from a bottom half handler. Preemption | |
401 | * must be disabled when calling this function. | |
402 | */ | |
403 | void smp_call_function_many(const struct cpumask *mask, | |
404 | smp_call_func_t func, void *info, bool wait) | |
405 | { | |
406 | struct call_function_data *cfd; | |
407 | int cpu, next_cpu, this_cpu = smp_processor_id(); | |
408 | ||
409 | /* | |
410 | * Can deadlock when called with interrupts disabled. | |
411 | * We allow cpu's that are not yet online though, as no one else can | |
412 | * send smp call function interrupt to this cpu and as such deadlocks | |
413 | * can't happen. | |
414 | */ | |
415 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() | |
416 | && !oops_in_progress && !early_boot_irqs_disabled); | |
417 | ||
418 | /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ | |
419 | cpu = cpumask_first_and(mask, cpu_online_mask); | |
420 | if (cpu == this_cpu) | |
421 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask); | |
422 | ||
423 | /* No online cpus? We're done. */ | |
424 | if (cpu >= nr_cpu_ids) | |
425 | return; | |
426 | ||
427 | /* Do we have another CPU which isn't us? */ | |
428 | next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); | |
429 | if (next_cpu == this_cpu) | |
430 | next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); | |
431 | ||
432 | /* Fastpath: do that cpu by itself. */ | |
433 | if (next_cpu >= nr_cpu_ids) { | |
434 | smp_call_function_single(cpu, func, info, wait); | |
435 | return; | |
436 | } | |
437 | ||
438 | cfd = this_cpu_ptr(&cfd_data); | |
439 | ||
440 | cpumask_and(cfd->cpumask, mask, cpu_online_mask); | |
441 | __cpumask_clear_cpu(this_cpu, cfd->cpumask); | |
442 | ||
443 | /* Some callers race with other cpus changing the passed mask */ | |
444 | if (unlikely(!cpumask_weight(cfd->cpumask))) | |
445 | return; | |
446 | ||
447 | cpumask_clear(cfd->cpumask_ipi); | |
448 | for_each_cpu(cpu, cfd->cpumask) { | |
449 | call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu); | |
450 | ||
451 | csd_lock(csd); | |
452 | if (wait) | |
453 | csd->flags |= CSD_FLAG_SYNCHRONOUS; | |
454 | csd->func = func; | |
455 | csd->info = info; | |
456 | if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) | |
457 | __cpumask_set_cpu(cpu, cfd->cpumask_ipi); | |
458 | } | |
459 | ||
460 | /* Send a message to all CPUs in the map */ | |
461 | arch_send_call_function_ipi_mask(cfd->cpumask_ipi); | |
462 | ||
463 | if (wait) { | |
464 | for_each_cpu(cpu, cfd->cpumask) { | |
465 | call_single_data_t *csd; | |
466 | ||
467 | csd = per_cpu_ptr(cfd->csd, cpu); | |
468 | csd_lock_wait(csd); | |
469 | } | |
470 | } | |
471 | } | |
472 | EXPORT_SYMBOL(smp_call_function_many); | |
473 | ||
474 | /** | |
475 | * smp_call_function(): Run a function on all other CPUs. | |
476 | * @func: The function to run. This must be fast and non-blocking. | |
477 | * @info: An arbitrary pointer to pass to the function. | |
478 | * @wait: If true, wait (atomically) until function has completed | |
479 | * on other CPUs. | |
480 | * | |
481 | * Returns 0. | |
482 | * | |
483 | * If @wait is true, then returns once @func has returned; otherwise | |
484 | * it returns just before the target cpu calls @func. | |
485 | * | |
486 | * You must not call this function with disabled interrupts or from a | |
487 | * hardware interrupt handler or from a bottom half handler. | |
488 | */ | |
489 | int smp_call_function(smp_call_func_t func, void *info, int wait) | |
490 | { | |
491 | preempt_disable(); | |
492 | smp_call_function_many(cpu_online_mask, func, info, wait); | |
493 | preempt_enable(); | |
494 | ||
495 | return 0; | |
496 | } | |
497 | EXPORT_SYMBOL(smp_call_function); | |
498 | ||
499 | /* Setup configured maximum number of CPUs to activate */ | |
500 | unsigned int setup_max_cpus = NR_CPUS; | |
501 | EXPORT_SYMBOL(setup_max_cpus); | |
502 | ||
503 | ||
504 | /* | |
505 | * Setup routine for controlling SMP activation | |
506 | * | |
507 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP | |
508 | * activation entirely (the MPS table probe still happens, though). | |
509 | * | |
510 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer | |
511 | * greater than 0, limits the maximum number of CPUs activated in | |
512 | * SMP mode to <NUM>. | |
513 | */ | |
514 | ||
515 | void __weak arch_disable_smp_support(void) { } | |
516 | ||
517 | static int __init nosmp(char *str) | |
518 | { | |
519 | setup_max_cpus = 0; | |
520 | arch_disable_smp_support(); | |
521 | ||
522 | return 0; | |
523 | } | |
524 | ||
525 | early_param("nosmp", nosmp); | |
526 | ||
527 | /* this is hard limit */ | |
528 | static int __init nrcpus(char *str) | |
529 | { | |
530 | int nr_cpus; | |
531 | ||
532 | get_option(&str, &nr_cpus); | |
533 | if (nr_cpus > 0 && nr_cpus < nr_cpu_ids) | |
534 | nr_cpu_ids = nr_cpus; | |
535 | ||
536 | return 0; | |
537 | } | |
538 | ||
539 | early_param("nr_cpus", nrcpus); | |
540 | ||
541 | static int __init maxcpus(char *str) | |
542 | { | |
543 | get_option(&str, &setup_max_cpus); | |
544 | if (setup_max_cpus == 0) | |
545 | arch_disable_smp_support(); | |
546 | ||
547 | return 0; | |
548 | } | |
549 | ||
550 | early_param("maxcpus", maxcpus); | |
551 | ||
552 | /* Setup number of possible processor ids */ | |
553 | unsigned int nr_cpu_ids __read_mostly = NR_CPUS; | |
554 | EXPORT_SYMBOL(nr_cpu_ids); | |
555 | ||
556 | /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ | |
557 | void __init setup_nr_cpu_ids(void) | |
558 | { | |
559 | nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1; | |
560 | } | |
561 | ||
562 | /* Called by boot processor to activate the rest. */ | |
563 | void __init smp_init(void) | |
564 | { | |
565 | int num_nodes, num_cpus; | |
566 | unsigned int cpu; | |
567 | ||
568 | idle_threads_init(); | |
569 | cpuhp_threads_init(); | |
570 | ||
571 | pr_info("Bringing up secondary CPUs ...\n"); | |
572 | ||
573 | /* FIXME: This should be done in userspace --RR */ | |
574 | for_each_present_cpu(cpu) { | |
575 | if (num_online_cpus() >= setup_max_cpus) | |
576 | break; | |
577 | if (!cpu_online(cpu)) | |
578 | cpu_up(cpu); | |
579 | } | |
580 | ||
581 | num_nodes = num_online_nodes(); | |
582 | num_cpus = num_online_cpus(); | |
583 | pr_info("Brought up %d node%s, %d CPU%s\n", | |
584 | num_nodes, (num_nodes > 1 ? "s" : ""), | |
585 | num_cpus, (num_cpus > 1 ? "s" : "")); | |
586 | ||
587 | /* Final decision about SMT support */ | |
588 | cpu_smt_check_topology(); | |
589 | /* Any cleanup work */ | |
590 | smp_cpus_done(setup_max_cpus); | |
591 | } | |
592 | ||
593 | /* | |
594 | * Call a function on all processors. May be used during early boot while | |
595 | * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead | |
596 | * of local_irq_disable/enable(). | |
597 | */ | |
598 | int on_each_cpu(void (*func) (void *info), void *info, int wait) | |
599 | { | |
600 | unsigned long flags; | |
601 | int ret = 0; | |
602 | ||
603 | preempt_disable(); | |
604 | ret = smp_call_function(func, info, wait); | |
605 | local_irq_save(flags); | |
606 | func(info); | |
607 | local_irq_restore(flags); | |
608 | preempt_enable(); | |
609 | return ret; | |
610 | } | |
611 | EXPORT_SYMBOL(on_each_cpu); | |
612 | ||
613 | /** | |
614 | * on_each_cpu_mask(): Run a function on processors specified by | |
615 | * cpumask, which may include the local processor. | |
616 | * @mask: The set of cpus to run on (only runs on online subset). | |
617 | * @func: The function to run. This must be fast and non-blocking. | |
618 | * @info: An arbitrary pointer to pass to the function. | |
619 | * @wait: If true, wait (atomically) until function has completed | |
620 | * on other CPUs. | |
621 | * | |
622 | * If @wait is true, then returns once @func has returned. | |
623 | * | |
624 | * You must not call this function with disabled interrupts or from a | |
625 | * hardware interrupt handler or from a bottom half handler. The | |
626 | * exception is that it may be used during early boot while | |
627 | * early_boot_irqs_disabled is set. | |
628 | */ | |
629 | void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, | |
630 | void *info, bool wait) | |
631 | { | |
632 | int cpu = get_cpu(); | |
633 | ||
634 | smp_call_function_many(mask, func, info, wait); | |
635 | if (cpumask_test_cpu(cpu, mask)) { | |
636 | unsigned long flags; | |
637 | local_irq_save(flags); | |
638 | func(info); | |
639 | local_irq_restore(flags); | |
640 | } | |
641 | put_cpu(); | |
642 | } | |
643 | EXPORT_SYMBOL(on_each_cpu_mask); | |
644 | ||
645 | /* | |
646 | * on_each_cpu_cond(): Call a function on each processor for which | |
647 | * the supplied function cond_func returns true, optionally waiting | |
648 | * for all the required CPUs to finish. This may include the local | |
649 | * processor. | |
650 | * @cond_func: A callback function that is passed a cpu id and | |
651 | * the the info parameter. The function is called | |
652 | * with preemption disabled. The function should | |
653 | * return a blooean value indicating whether to IPI | |
654 | * the specified CPU. | |
655 | * @func: The function to run on all applicable CPUs. | |
656 | * This must be fast and non-blocking. | |
657 | * @info: An arbitrary pointer to pass to both functions. | |
658 | * @wait: If true, wait (atomically) until function has | |
659 | * completed on other CPUs. | |
660 | * @gfp_flags: GFP flags to use when allocating the cpumask | |
661 | * used internally by the function. | |
662 | * | |
663 | * The function might sleep if the GFP flags indicates a non | |
664 | * atomic allocation is allowed. | |
665 | * | |
666 | * Preemption is disabled to protect against CPUs going offline but not online. | |
667 | * CPUs going online during the call will not be seen or sent an IPI. | |
668 | * | |
669 | * You must not call this function with disabled interrupts or | |
670 | * from a hardware interrupt handler or from a bottom half handler. | |
671 | */ | |
672 | void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), | |
673 | smp_call_func_t func, void *info, bool wait, | |
674 | gfp_t gfp_flags) | |
675 | { | |
676 | cpumask_var_t cpus; | |
677 | int cpu, ret; | |
678 | ||
679 | might_sleep_if(gfpflags_allow_blocking(gfp_flags)); | |
680 | ||
681 | if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) { | |
682 | preempt_disable(); | |
683 | for_each_online_cpu(cpu) | |
684 | if (cond_func(cpu, info)) | |
685 | cpumask_set_cpu(cpu, cpus); | |
686 | on_each_cpu_mask(cpus, func, info, wait); | |
687 | preempt_enable(); | |
688 | free_cpumask_var(cpus); | |
689 | } else { | |
690 | /* | |
691 | * No free cpumask, bother. No matter, we'll | |
692 | * just have to IPI them one by one. | |
693 | */ | |
694 | preempt_disable(); | |
695 | for_each_online_cpu(cpu) | |
696 | if (cond_func(cpu, info)) { | |
697 | ret = smp_call_function_single(cpu, func, | |
698 | info, wait); | |
699 | WARN_ON_ONCE(ret); | |
700 | } | |
701 | preempt_enable(); | |
702 | } | |
703 | } | |
704 | EXPORT_SYMBOL(on_each_cpu_cond); | |
705 | ||
706 | static void do_nothing(void *unused) | |
707 | { | |
708 | } | |
709 | ||
710 | /** | |
711 | * kick_all_cpus_sync - Force all cpus out of idle | |
712 | * | |
713 | * Used to synchronize the update of pm_idle function pointer. It's | |
714 | * called after the pointer is updated and returns after the dummy | |
715 | * callback function has been executed on all cpus. The execution of | |
716 | * the function can only happen on the remote cpus after they have | |
717 | * left the idle function which had been called via pm_idle function | |
718 | * pointer. So it's guaranteed that nothing uses the previous pointer | |
719 | * anymore. | |
720 | */ | |
721 | void kick_all_cpus_sync(void) | |
722 | { | |
723 | /* Make sure the change is visible before we kick the cpus */ | |
724 | smp_mb(); | |
725 | smp_call_function(do_nothing, NULL, 1); | |
726 | } | |
727 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync); | |
728 | ||
729 | /** | |
730 | * wake_up_all_idle_cpus - break all cpus out of idle | |
731 | * wake_up_all_idle_cpus try to break all cpus which is in idle state even | |
732 | * including idle polling cpus, for non-idle cpus, we will do nothing | |
733 | * for them. | |
734 | */ | |
735 | void wake_up_all_idle_cpus(void) | |
736 | { | |
737 | int cpu; | |
738 | ||
739 | preempt_disable(); | |
740 | for_each_online_cpu(cpu) { | |
741 | if (cpu == smp_processor_id()) | |
742 | continue; | |
743 | ||
744 | wake_up_if_idle(cpu); | |
745 | } | |
746 | preempt_enable(); | |
747 | } | |
748 | EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus); | |
749 | ||
750 | /** | |
751 | * smp_call_on_cpu - Call a function on a specific cpu | |
752 | * | |
753 | * Used to call a function on a specific cpu and wait for it to return. | |
754 | * Optionally make sure the call is done on a specified physical cpu via vcpu | |
755 | * pinning in order to support virtualized environments. | |
756 | */ | |
757 | struct smp_call_on_cpu_struct { | |
758 | struct work_struct work; | |
759 | struct completion done; | |
760 | int (*func)(void *); | |
761 | void *data; | |
762 | int ret; | |
763 | int cpu; | |
764 | }; | |
765 | ||
766 | static void smp_call_on_cpu_callback(struct work_struct *work) | |
767 | { | |
768 | struct smp_call_on_cpu_struct *sscs; | |
769 | ||
770 | sscs = container_of(work, struct smp_call_on_cpu_struct, work); | |
771 | if (sscs->cpu >= 0) | |
772 | hypervisor_pin_vcpu(sscs->cpu); | |
773 | sscs->ret = sscs->func(sscs->data); | |
774 | if (sscs->cpu >= 0) | |
775 | hypervisor_pin_vcpu(-1); | |
776 | ||
777 | complete(&sscs->done); | |
778 | } | |
779 | ||
780 | int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys) | |
781 | { | |
782 | struct smp_call_on_cpu_struct sscs = { | |
783 | .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done), | |
784 | .func = func, | |
785 | .data = par, | |
786 | .cpu = phys ? cpu : -1, | |
787 | }; | |
788 | ||
789 | INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback); | |
790 | ||
791 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) | |
792 | return -ENXIO; | |
793 | ||
794 | queue_work_on(cpu, system_wq, &sscs.work); | |
795 | wait_for_completion(&sscs.done); | |
796 | ||
797 | return sscs.ret; | |
798 | } | |
799 | EXPORT_SYMBOL_GPL(smp_call_on_cpu); |