Commit | Line | Data |
---|---|---|
1142d810 TH |
1 | /* |
2 | * kernel/stop_machine.c | |
3 | * | |
4 | * Copyright (C) 2008, 2005 IBM Corporation. | |
5 | * Copyright (C) 2008, 2005 Rusty Russell rusty@rustcorp.com.au | |
6 | * Copyright (C) 2010 SUSE Linux Products GmbH | |
7 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> | |
8 | * | |
9 | * This file is released under the GPLv2 and any later version. | |
e5582ca2 | 10 | */ |
1142d810 | 11 | #include <linux/completion.h> |
1da177e4 | 12 | #include <linux/cpu.h> |
1142d810 | 13 | #include <linux/init.h> |
ee527cd3 PB |
14 | #include <linux/kthread.h> |
15 | #include <linux/module.h> | |
1142d810 | 16 | #include <linux/percpu.h> |
ee527cd3 PB |
17 | #include <linux/sched.h> |
18 | #include <linux/stop_machine.h> | |
a12bb444 | 19 | #include <linux/interrupt.h> |
1142d810 | 20 | #include <linux/kallsyms.h> |
a12bb444 | 21 | |
60063497 | 22 | #include <linux/atomic.h> |
1142d810 TH |
23 | |
24 | /* | |
25 | * Structure to determine completion condition and record errors. May | |
26 | * be shared by works on different cpus. | |
27 | */ | |
28 | struct cpu_stop_done { | |
29 | atomic_t nr_todo; /* nr left to execute */ | |
30 | bool executed; /* actually executed? */ | |
31 | int ret; /* collected return value */ | |
32 | struct completion completion; /* fired if nr_todo reaches 0 */ | |
33 | }; | |
34 | ||
35 | /* the actual stopper, one per every possible cpu, enabled on online cpus */ | |
36 | struct cpu_stopper { | |
37 | spinlock_t lock; | |
878ae127 | 38 | bool enabled; /* is this stopper enabled? */ |
1142d810 TH |
39 | struct list_head works; /* list of pending works */ |
40 | struct task_struct *thread; /* stopper thread */ | |
1142d810 TH |
41 | }; |
42 | ||
43 | static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper); | |
44 | ||
45 | static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo) | |
46 | { | |
47 | memset(done, 0, sizeof(*done)); | |
48 | atomic_set(&done->nr_todo, nr_todo); | |
49 | init_completion(&done->completion); | |
50 | } | |
51 | ||
52 | /* signal completion unless @done is NULL */ | |
53 | static void cpu_stop_signal_done(struct cpu_stop_done *done, bool executed) | |
54 | { | |
55 | if (done) { | |
56 | if (executed) | |
57 | done->executed = true; | |
58 | if (atomic_dec_and_test(&done->nr_todo)) | |
59 | complete(&done->completion); | |
60 | } | |
61 | } | |
62 | ||
63 | /* queue @work to @stopper. if offline, @work is completed immediately */ | |
64 | static void cpu_stop_queue_work(struct cpu_stopper *stopper, | |
65 | struct cpu_stop_work *work) | |
66 | { | |
67 | unsigned long flags; | |
68 | ||
69 | spin_lock_irqsave(&stopper->lock, flags); | |
70 | ||
71 | if (stopper->enabled) { | |
72 | list_add_tail(&work->list, &stopper->works); | |
73 | wake_up_process(stopper->thread); | |
74 | } else | |
75 | cpu_stop_signal_done(work->done, false); | |
76 | ||
77 | spin_unlock_irqrestore(&stopper->lock, flags); | |
78 | } | |
79 | ||
80 | /** | |
81 | * stop_one_cpu - stop a cpu | |
82 | * @cpu: cpu to stop | |
83 | * @fn: function to execute | |
84 | * @arg: argument to @fn | |
85 | * | |
86 | * Execute @fn(@arg) on @cpu. @fn is run in a process context with | |
87 | * the highest priority preempting any task on the cpu and | |
88 | * monopolizing it. This function returns after the execution is | |
89 | * complete. | |
90 | * | |
91 | * This function doesn't guarantee @cpu stays online till @fn | |
92 | * completes. If @cpu goes down in the middle, execution may happen | |
93 | * partially or fully on different cpus. @fn should either be ready | |
94 | * for that or the caller should ensure that @cpu stays online until | |
95 | * this function completes. | |
96 | * | |
97 | * CONTEXT: | |
98 | * Might sleep. | |
99 | * | |
100 | * RETURNS: | |
101 | * -ENOENT if @fn(@arg) was not executed because @cpu was offline; | |
102 | * otherwise, the return value of @fn. | |
103 | */ | |
104 | int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) | |
105 | { | |
106 | struct cpu_stop_done done; | |
107 | struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done }; | |
108 | ||
109 | cpu_stop_init_done(&done, 1); | |
110 | cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), &work); | |
111 | wait_for_completion(&done.completion); | |
112 | return done.executed ? done.ret : -ENOENT; | |
113 | } | |
114 | ||
115 | /** | |
116 | * stop_one_cpu_nowait - stop a cpu but don't wait for completion | |
117 | * @cpu: cpu to stop | |
118 | * @fn: function to execute | |
119 | * @arg: argument to @fn | |
120 | * | |
121 | * Similar to stop_one_cpu() but doesn't wait for completion. The | |
122 | * caller is responsible for ensuring @work_buf is currently unused | |
123 | * and will remain untouched until stopper starts executing @fn. | |
124 | * | |
125 | * CONTEXT: | |
126 | * Don't care. | |
127 | */ | |
128 | void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, | |
129 | struct cpu_stop_work *work_buf) | |
130 | { | |
131 | *work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, }; | |
132 | cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), work_buf); | |
133 | } | |
134 | ||
135 | /* static data for stop_cpus */ | |
192d8857 | 136 | static DEFINE_MUTEX(stop_cpus_mutex); |
1142d810 TH |
137 | static DEFINE_PER_CPU(struct cpu_stop_work, stop_cpus_work); |
138 | ||
fd7355ba TH |
139 | static void queue_stop_cpus_work(const struct cpumask *cpumask, |
140 | cpu_stop_fn_t fn, void *arg, | |
141 | struct cpu_stop_done *done) | |
1142d810 TH |
142 | { |
143 | struct cpu_stop_work *work; | |
1142d810 TH |
144 | unsigned int cpu; |
145 | ||
146 | /* initialize works and done */ | |
147 | for_each_cpu(cpu, cpumask) { | |
148 | work = &per_cpu(stop_cpus_work, cpu); | |
149 | work->fn = fn; | |
150 | work->arg = arg; | |
fd7355ba | 151 | work->done = done; |
1142d810 | 152 | } |
1142d810 TH |
153 | |
154 | /* | |
155 | * Disable preemption while queueing to avoid getting | |
156 | * preempted by a stopper which might wait for other stoppers | |
157 | * to enter @fn which can lead to deadlock. | |
158 | */ | |
159 | preempt_disable(); | |
160 | for_each_cpu(cpu, cpumask) | |
161 | cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), | |
162 | &per_cpu(stop_cpus_work, cpu)); | |
163 | preempt_enable(); | |
fd7355ba | 164 | } |
1142d810 | 165 | |
fd7355ba TH |
166 | static int __stop_cpus(const struct cpumask *cpumask, |
167 | cpu_stop_fn_t fn, void *arg) | |
168 | { | |
169 | struct cpu_stop_done done; | |
170 | ||
171 | cpu_stop_init_done(&done, cpumask_weight(cpumask)); | |
172 | queue_stop_cpus_work(cpumask, fn, arg, &done); | |
1142d810 TH |
173 | wait_for_completion(&done.completion); |
174 | return done.executed ? done.ret : -ENOENT; | |
175 | } | |
176 | ||
177 | /** | |
178 | * stop_cpus - stop multiple cpus | |
179 | * @cpumask: cpus to stop | |
180 | * @fn: function to execute | |
181 | * @arg: argument to @fn | |
182 | * | |
183 | * Execute @fn(@arg) on online cpus in @cpumask. On each target cpu, | |
184 | * @fn is run in a process context with the highest priority | |
185 | * preempting any task on the cpu and monopolizing it. This function | |
186 | * returns after all executions are complete. | |
187 | * | |
188 | * This function doesn't guarantee the cpus in @cpumask stay online | |
189 | * till @fn completes. If some cpus go down in the middle, execution | |
190 | * on the cpu may happen partially or fully on different cpus. @fn | |
191 | * should either be ready for that or the caller should ensure that | |
192 | * the cpus stay online until this function completes. | |
193 | * | |
194 | * All stop_cpus() calls are serialized making it safe for @fn to wait | |
195 | * for all cpus to start executing it. | |
196 | * | |
197 | * CONTEXT: | |
198 | * Might sleep. | |
199 | * | |
200 | * RETURNS: | |
201 | * -ENOENT if @fn(@arg) was not executed at all because all cpus in | |
202 | * @cpumask were offline; otherwise, 0 if all executions of @fn | |
203 | * returned 0, any non zero return value if any returned non zero. | |
204 | */ | |
205 | int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg) | |
206 | { | |
207 | int ret; | |
208 | ||
209 | /* static works are used, process one request at a time */ | |
210 | mutex_lock(&stop_cpus_mutex); | |
211 | ret = __stop_cpus(cpumask, fn, arg); | |
212 | mutex_unlock(&stop_cpus_mutex); | |
213 | return ret; | |
214 | } | |
215 | ||
216 | /** | |
217 | * try_stop_cpus - try to stop multiple cpus | |
218 | * @cpumask: cpus to stop | |
219 | * @fn: function to execute | |
220 | * @arg: argument to @fn | |
221 | * | |
222 | * Identical to stop_cpus() except that it fails with -EAGAIN if | |
223 | * someone else is already using the facility. | |
224 | * | |
225 | * CONTEXT: | |
226 | * Might sleep. | |
227 | * | |
228 | * RETURNS: | |
229 | * -EAGAIN if someone else is already stopping cpus, -ENOENT if | |
230 | * @fn(@arg) was not executed at all because all cpus in @cpumask were | |
231 | * offline; otherwise, 0 if all executions of @fn returned 0, any non | |
232 | * zero return value if any returned non zero. | |
233 | */ | |
234 | int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg) | |
235 | { | |
236 | int ret; | |
237 | ||
238 | /* static works are used, process one request at a time */ | |
239 | if (!mutex_trylock(&stop_cpus_mutex)) | |
240 | return -EAGAIN; | |
241 | ret = __stop_cpus(cpumask, fn, arg); | |
242 | mutex_unlock(&stop_cpus_mutex); | |
243 | return ret; | |
244 | } | |
245 | ||
246 | static int cpu_stopper_thread(void *data) | |
247 | { | |
248 | struct cpu_stopper *stopper = data; | |
249 | struct cpu_stop_work *work; | |
250 | int ret; | |
251 | ||
252 | repeat: | |
253 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
254 | ||
255 | if (kthread_should_stop()) { | |
256 | __set_current_state(TASK_RUNNING); | |
257 | return 0; | |
258 | } | |
259 | ||
260 | work = NULL; | |
261 | spin_lock_irq(&stopper->lock); | |
262 | if (!list_empty(&stopper->works)) { | |
263 | work = list_first_entry(&stopper->works, | |
264 | struct cpu_stop_work, list); | |
265 | list_del_init(&work->list); | |
266 | } | |
267 | spin_unlock_irq(&stopper->lock); | |
268 | ||
269 | if (work) { | |
270 | cpu_stop_fn_t fn = work->fn; | |
271 | void *arg = work->arg; | |
272 | struct cpu_stop_done *done = work->done; | |
ca51c5a7 | 273 | char ksym_buf[KSYM_NAME_LEN] __maybe_unused; |
1142d810 TH |
274 | |
275 | __set_current_state(TASK_RUNNING); | |
276 | ||
277 | /* cpu stop callbacks are not allowed to sleep */ | |
278 | preempt_disable(); | |
279 | ||
280 | ret = fn(arg); | |
281 | if (ret) | |
282 | done->ret = ret; | |
283 | ||
284 | /* restore preemption and check it's still balanced */ | |
285 | preempt_enable(); | |
286 | WARN_ONCE(preempt_count(), | |
287 | "cpu_stop: %s(%p) leaked preempt count\n", | |
288 | kallsyms_lookup((unsigned long)fn, NULL, NULL, NULL, | |
289 | ksym_buf), arg); | |
290 | ||
291 | cpu_stop_signal_done(done, true); | |
292 | } else | |
293 | schedule(); | |
294 | ||
295 | goto repeat; | |
296 | } | |
297 | ||
34f971f6 PZ |
298 | extern void sched_set_stop_task(int cpu, struct task_struct *stop); |
299 | ||
1142d810 TH |
300 | /* manage stopper for a cpu, mostly lifted from sched migration thread mgmt */ |
301 | static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb, | |
302 | unsigned long action, void *hcpu) | |
303 | { | |
1142d810 TH |
304 | unsigned int cpu = (unsigned long)hcpu; |
305 | struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); | |
1142d810 TH |
306 | struct task_struct *p; |
307 | ||
308 | switch (action & ~CPU_TASKS_FROZEN) { | |
309 | case CPU_UP_PREPARE: | |
310 | BUG_ON(stopper->thread || stopper->enabled || | |
311 | !list_empty(&stopper->works)); | |
94dcf29a ED |
312 | p = kthread_create_on_node(cpu_stopper_thread, |
313 | stopper, | |
314 | cpu_to_node(cpu), | |
315 | "migration/%d", cpu); | |
1142d810 | 316 | if (IS_ERR(p)) |
4ce6494d | 317 | return notifier_from_errno(PTR_ERR(p)); |
1142d810 | 318 | get_task_struct(p); |
34f971f6 PZ |
319 | kthread_bind(p, cpu); |
320 | sched_set_stop_task(cpu, p); | |
1142d810 TH |
321 | stopper->thread = p; |
322 | break; | |
323 | ||
324 | case CPU_ONLINE: | |
1142d810 TH |
325 | /* strictly unnecessary, as first user will wake it */ |
326 | wake_up_process(stopper->thread); | |
327 | /* mark enabled */ | |
328 | spin_lock_irq(&stopper->lock); | |
329 | stopper->enabled = true; | |
330 | spin_unlock_irq(&stopper->lock); | |
331 | break; | |
332 | ||
333 | #ifdef CONFIG_HOTPLUG_CPU | |
334 | case CPU_UP_CANCELED: | |
54e88fad | 335 | case CPU_POST_DEAD: |
9c6f7e43 IM |
336 | { |
337 | struct cpu_stop_work *work; | |
338 | ||
34f971f6 | 339 | sched_set_stop_task(cpu, NULL); |
1142d810 TH |
340 | /* kill the stopper */ |
341 | kthread_stop(stopper->thread); | |
342 | /* drain remaining works */ | |
343 | spin_lock_irq(&stopper->lock); | |
344 | list_for_each_entry(work, &stopper->works, list) | |
345 | cpu_stop_signal_done(work->done, false); | |
346 | stopper->enabled = false; | |
347 | spin_unlock_irq(&stopper->lock); | |
348 | /* release the stopper */ | |
349 | put_task_struct(stopper->thread); | |
350 | stopper->thread = NULL; | |
351 | break; | |
9c6f7e43 | 352 | } |
1142d810 TH |
353 | #endif |
354 | } | |
355 | ||
356 | return NOTIFY_OK; | |
357 | } | |
358 | ||
359 | /* | |
360 | * Give it a higher priority so that cpu stopper is available to other | |
361 | * cpu notifiers. It currently shares the same priority as sched | |
362 | * migration_notifier. | |
363 | */ | |
364 | static struct notifier_block __cpuinitdata cpu_stop_cpu_notifier = { | |
365 | .notifier_call = cpu_stop_cpu_callback, | |
366 | .priority = 10, | |
367 | }; | |
368 | ||
369 | static int __init cpu_stop_init(void) | |
370 | { | |
371 | void *bcpu = (void *)(long)smp_processor_id(); | |
372 | unsigned int cpu; | |
373 | int err; | |
374 | ||
375 | for_each_possible_cpu(cpu) { | |
376 | struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); | |
377 | ||
378 | spin_lock_init(&stopper->lock); | |
379 | INIT_LIST_HEAD(&stopper->works); | |
380 | } | |
381 | ||
382 | /* start one for the boot cpu */ | |
383 | err = cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_UP_PREPARE, | |
384 | bcpu); | |
4ce6494d | 385 | BUG_ON(err != NOTIFY_OK); |
1142d810 TH |
386 | cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_ONLINE, bcpu); |
387 | register_cpu_notifier(&cpu_stop_cpu_notifier); | |
388 | ||
389 | return 0; | |
390 | } | |
391 | early_initcall(cpu_stop_init); | |
1da177e4 | 392 | |
bbf1bb3e TH |
393 | #ifdef CONFIG_STOP_MACHINE |
394 | ||
ffdb5976 | 395 | /* This controls the threads on each CPU. */ |
1da177e4 | 396 | enum stopmachine_state { |
ffdb5976 RR |
397 | /* Dummy starting state for thread. */ |
398 | STOPMACHINE_NONE, | |
399 | /* Awaiting everyone to be scheduled. */ | |
1da177e4 | 400 | STOPMACHINE_PREPARE, |
ffdb5976 | 401 | /* Disable interrupts. */ |
1da177e4 | 402 | STOPMACHINE_DISABLE_IRQ, |
ffdb5976 | 403 | /* Run the function */ |
5c2aed62 | 404 | STOPMACHINE_RUN, |
ffdb5976 | 405 | /* Exit */ |
1da177e4 LT |
406 | STOPMACHINE_EXIT, |
407 | }; | |
408 | ||
5c2aed62 | 409 | struct stop_machine_data { |
3fc1f1e2 TH |
410 | int (*fn)(void *); |
411 | void *data; | |
412 | /* Like num_online_cpus(), but hotplug cpu uses us, so we need this. */ | |
413 | unsigned int num_threads; | |
414 | const struct cpumask *active_cpus; | |
415 | ||
416 | enum stopmachine_state state; | |
417 | atomic_t thread_ack; | |
ffdb5976 | 418 | }; |
5c2aed62 | 419 | |
3fc1f1e2 TH |
420 | static void set_state(struct stop_machine_data *smdata, |
421 | enum stopmachine_state newstate) | |
1da177e4 | 422 | { |
ffdb5976 | 423 | /* Reset ack counter. */ |
3fc1f1e2 | 424 | atomic_set(&smdata->thread_ack, smdata->num_threads); |
ffdb5976 | 425 | smp_wmb(); |
3fc1f1e2 | 426 | smdata->state = newstate; |
1da177e4 LT |
427 | } |
428 | ||
ffdb5976 | 429 | /* Last one to ack a state moves to the next state. */ |
3fc1f1e2 | 430 | static void ack_state(struct stop_machine_data *smdata) |
1da177e4 | 431 | { |
3fc1f1e2 TH |
432 | if (atomic_dec_and_test(&smdata->thread_ack)) |
433 | set_state(smdata, smdata->state + 1); | |
1da177e4 LT |
434 | } |
435 | ||
3fc1f1e2 TH |
436 | /* This is the cpu_stop function which stops the CPU. */ |
437 | static int stop_machine_cpu_stop(void *data) | |
1da177e4 | 438 | { |
3fc1f1e2 | 439 | struct stop_machine_data *smdata = data; |
ffdb5976 | 440 | enum stopmachine_state curstate = STOPMACHINE_NONE; |
3fc1f1e2 | 441 | int cpu = smp_processor_id(), err = 0; |
f740e6cd | 442 | unsigned long flags; |
3fc1f1e2 TH |
443 | bool is_active; |
444 | ||
f740e6cd TH |
445 | /* |
446 | * When called from stop_machine_from_inactive_cpu(), irq might | |
447 | * already be disabled. Save the state and restore it on exit. | |
448 | */ | |
449 | local_save_flags(flags); | |
450 | ||
3fc1f1e2 TH |
451 | if (!smdata->active_cpus) |
452 | is_active = cpu == cpumask_first(cpu_online_mask); | |
453 | else | |
454 | is_active = cpumask_test_cpu(cpu, smdata->active_cpus); | |
c9583e55 | 455 | |
ffdb5976 RR |
456 | /* Simple state machine */ |
457 | do { | |
458 | /* Chill out and ensure we re-read stopmachine_state. */ | |
3401a61e | 459 | cpu_relax(); |
3fc1f1e2 TH |
460 | if (smdata->state != curstate) { |
461 | curstate = smdata->state; | |
ffdb5976 RR |
462 | switch (curstate) { |
463 | case STOPMACHINE_DISABLE_IRQ: | |
464 | local_irq_disable(); | |
465 | hard_irq_disable(); | |
466 | break; | |
467 | case STOPMACHINE_RUN: | |
3fc1f1e2 TH |
468 | if (is_active) |
469 | err = smdata->fn(smdata->data); | |
ffdb5976 RR |
470 | break; |
471 | default: | |
472 | break; | |
473 | } | |
3fc1f1e2 | 474 | ack_state(smdata); |
ffdb5976 RR |
475 | } |
476 | } while (curstate != STOPMACHINE_EXIT); | |
1da177e4 | 477 | |
f740e6cd | 478 | local_irq_restore(flags); |
3fc1f1e2 | 479 | return err; |
1da177e4 LT |
480 | } |
481 | ||
41c7bb95 | 482 | int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus) |
1da177e4 | 483 | { |
3fc1f1e2 TH |
484 | struct stop_machine_data smdata = { .fn = fn, .data = data, |
485 | .num_threads = num_online_cpus(), | |
486 | .active_cpus = cpus }; | |
487 | ||
488 | /* Set the initial state and stop all online cpus. */ | |
489 | set_state(&smdata, STOPMACHINE_PREPARE); | |
490 | return stop_cpus(cpu_online_mask, stop_machine_cpu_stop, &smdata); | |
1da177e4 LT |
491 | } |
492 | ||
41c7bb95 | 493 | int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus) |
1da177e4 | 494 | { |
1da177e4 LT |
495 | int ret; |
496 | ||
497 | /* No CPUs can come up or down during this. */ | |
86ef5c9a | 498 | get_online_cpus(); |
eeec4fad | 499 | ret = __stop_machine(fn, data, cpus); |
86ef5c9a | 500 | put_online_cpus(); |
1da177e4 LT |
501 | return ret; |
502 | } | |
eeec4fad | 503 | EXPORT_SYMBOL_GPL(stop_machine); |
bbf1bb3e | 504 | |
f740e6cd TH |
505 | /** |
506 | * stop_machine_from_inactive_cpu - stop_machine() from inactive CPU | |
507 | * @fn: the function to run | |
508 | * @data: the data ptr for the @fn() | |
509 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu) | |
510 | * | |
511 | * This is identical to stop_machine() but can be called from a CPU which | |
512 | * is not active. The local CPU is in the process of hotplug (so no other | |
513 | * CPU hotplug can start) and not marked active and doesn't have enough | |
514 | * context to sleep. | |
515 | * | |
516 | * This function provides stop_machine() functionality for such state by | |
517 | * using busy-wait for synchronization and executing @fn directly for local | |
518 | * CPU. | |
519 | * | |
520 | * CONTEXT: | |
521 | * Local CPU is inactive. Temporarily stops all active CPUs. | |
522 | * | |
523 | * RETURNS: | |
524 | * 0 if all executions of @fn returned 0, any non zero return value if any | |
525 | * returned non zero. | |
526 | */ | |
527 | int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data, | |
528 | const struct cpumask *cpus) | |
529 | { | |
530 | struct stop_machine_data smdata = { .fn = fn, .data = data, | |
531 | .active_cpus = cpus }; | |
532 | struct cpu_stop_done done; | |
533 | int ret; | |
534 | ||
535 | /* Local CPU must be inactive and CPU hotplug in progress. */ | |
536 | BUG_ON(cpu_active(raw_smp_processor_id())); | |
537 | smdata.num_threads = num_active_cpus() + 1; /* +1 for local */ | |
538 | ||
539 | /* No proper task established and can't sleep - busy wait for lock. */ | |
540 | while (!mutex_trylock(&stop_cpus_mutex)) | |
541 | cpu_relax(); | |
542 | ||
543 | /* Schedule work on other CPUs and execute directly for local CPU */ | |
544 | set_state(&smdata, STOPMACHINE_PREPARE); | |
545 | cpu_stop_init_done(&done, num_active_cpus()); | |
546 | queue_stop_cpus_work(cpu_active_mask, stop_machine_cpu_stop, &smdata, | |
547 | &done); | |
548 | ret = stop_machine_cpu_stop(&smdata); | |
549 | ||
550 | /* Busy wait for completion. */ | |
551 | while (!completion_done(&done.completion)) | |
552 | cpu_relax(); | |
553 | ||
554 | mutex_unlock(&stop_cpus_mutex); | |
555 | return ret ?: done.ret; | |
556 | } | |
557 | ||
bbf1bb3e | 558 | #endif /* CONFIG_STOP_MACHINE */ |