Commit | Line | Data |
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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 | 14 | #include <linux/kthread.h> |
9984de1a | 15 | #include <linux/export.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> |
14e568e7 | 21 | #include <linux/smpboot.h> |
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 | 39 | struct list_head works; /* list of pending works */ |
1142d810 TH |
40 | }; |
41 | ||
42 | static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper); | |
860a0ffa | 43 | static DEFINE_PER_CPU(struct task_struct *, cpu_stopper_task); |
f445027e | 44 | static bool stop_machine_initialized = false; |
1142d810 TH |
45 | |
46 | static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo) | |
47 | { | |
48 | memset(done, 0, sizeof(*done)); | |
49 | atomic_set(&done->nr_todo, nr_todo); | |
50 | init_completion(&done->completion); | |
51 | } | |
52 | ||
53 | /* signal completion unless @done is NULL */ | |
54 | static void cpu_stop_signal_done(struct cpu_stop_done *done, bool executed) | |
55 | { | |
56 | if (done) { | |
57 | if (executed) | |
58 | done->executed = true; | |
59 | if (atomic_dec_and_test(&done->nr_todo)) | |
60 | complete(&done->completion); | |
61 | } | |
62 | } | |
63 | ||
64 | /* queue @work to @stopper. if offline, @work is completed immediately */ | |
860a0ffa | 65 | static void cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work) |
1142d810 | 66 | { |
860a0ffa TG |
67 | struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); |
68 | struct task_struct *p = per_cpu(cpu_stopper_task, cpu); | |
69 | ||
1142d810 TH |
70 | unsigned long flags; |
71 | ||
72 | spin_lock_irqsave(&stopper->lock, flags); | |
73 | ||
74 | if (stopper->enabled) { | |
75 | list_add_tail(&work->list, &stopper->works); | |
860a0ffa | 76 | wake_up_process(p); |
1142d810 TH |
77 | } else |
78 | cpu_stop_signal_done(work->done, false); | |
79 | ||
80 | spin_unlock_irqrestore(&stopper->lock, flags); | |
81 | } | |
82 | ||
83 | /** | |
84 | * stop_one_cpu - stop a cpu | |
85 | * @cpu: cpu to stop | |
86 | * @fn: function to execute | |
87 | * @arg: argument to @fn | |
88 | * | |
89 | * Execute @fn(@arg) on @cpu. @fn is run in a process context with | |
90 | * the highest priority preempting any task on the cpu and | |
91 | * monopolizing it. This function returns after the execution is | |
92 | * complete. | |
93 | * | |
94 | * This function doesn't guarantee @cpu stays online till @fn | |
95 | * completes. If @cpu goes down in the middle, execution may happen | |
96 | * partially or fully on different cpus. @fn should either be ready | |
97 | * for that or the caller should ensure that @cpu stays online until | |
98 | * this function completes. | |
99 | * | |
100 | * CONTEXT: | |
101 | * Might sleep. | |
102 | * | |
103 | * RETURNS: | |
104 | * -ENOENT if @fn(@arg) was not executed because @cpu was offline; | |
105 | * otherwise, the return value of @fn. | |
106 | */ | |
107 | int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) | |
108 | { | |
109 | struct cpu_stop_done done; | |
110 | struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done }; | |
111 | ||
112 | cpu_stop_init_done(&done, 1); | |
860a0ffa | 113 | cpu_stop_queue_work(cpu, &work); |
1142d810 TH |
114 | wait_for_completion(&done.completion); |
115 | return done.executed ? done.ret : -ENOENT; | |
116 | } | |
117 | ||
118 | /** | |
119 | * stop_one_cpu_nowait - stop a cpu but don't wait for completion | |
120 | * @cpu: cpu to stop | |
121 | * @fn: function to execute | |
122 | * @arg: argument to @fn | |
123 | * | |
124 | * Similar to stop_one_cpu() but doesn't wait for completion. The | |
125 | * caller is responsible for ensuring @work_buf is currently unused | |
126 | * and will remain untouched until stopper starts executing @fn. | |
127 | * | |
128 | * CONTEXT: | |
129 | * Don't care. | |
130 | */ | |
131 | void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, | |
132 | struct cpu_stop_work *work_buf) | |
133 | { | |
134 | *work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, }; | |
860a0ffa | 135 | cpu_stop_queue_work(cpu, work_buf); |
1142d810 TH |
136 | } |
137 | ||
138 | /* static data for stop_cpus */ | |
192d8857 | 139 | static DEFINE_MUTEX(stop_cpus_mutex); |
1142d810 TH |
140 | static DEFINE_PER_CPU(struct cpu_stop_work, stop_cpus_work); |
141 | ||
fd7355ba TH |
142 | static void queue_stop_cpus_work(const struct cpumask *cpumask, |
143 | cpu_stop_fn_t fn, void *arg, | |
144 | struct cpu_stop_done *done) | |
1142d810 TH |
145 | { |
146 | struct cpu_stop_work *work; | |
1142d810 TH |
147 | unsigned int cpu; |
148 | ||
149 | /* initialize works and done */ | |
150 | for_each_cpu(cpu, cpumask) { | |
151 | work = &per_cpu(stop_cpus_work, cpu); | |
152 | work->fn = fn; | |
153 | work->arg = arg; | |
fd7355ba | 154 | work->done = done; |
1142d810 | 155 | } |
1142d810 TH |
156 | |
157 | /* | |
158 | * Disable preemption while queueing to avoid getting | |
159 | * preempted by a stopper which might wait for other stoppers | |
160 | * to enter @fn which can lead to deadlock. | |
161 | */ | |
162 | preempt_disable(); | |
163 | for_each_cpu(cpu, cpumask) | |
860a0ffa | 164 | cpu_stop_queue_work(cpu, &per_cpu(stop_cpus_work, cpu)); |
1142d810 | 165 | preempt_enable(); |
fd7355ba | 166 | } |
1142d810 | 167 | |
fd7355ba TH |
168 | static int __stop_cpus(const struct cpumask *cpumask, |
169 | cpu_stop_fn_t fn, void *arg) | |
170 | { | |
171 | struct cpu_stop_done done; | |
172 | ||
173 | cpu_stop_init_done(&done, cpumask_weight(cpumask)); | |
174 | queue_stop_cpus_work(cpumask, fn, arg, &done); | |
1142d810 TH |
175 | wait_for_completion(&done.completion); |
176 | return done.executed ? done.ret : -ENOENT; | |
177 | } | |
178 | ||
179 | /** | |
180 | * stop_cpus - stop multiple cpus | |
181 | * @cpumask: cpus to stop | |
182 | * @fn: function to execute | |
183 | * @arg: argument to @fn | |
184 | * | |
185 | * Execute @fn(@arg) on online cpus in @cpumask. On each target cpu, | |
186 | * @fn is run in a process context with the highest priority | |
187 | * preempting any task on the cpu and monopolizing it. This function | |
188 | * returns after all executions are complete. | |
189 | * | |
190 | * This function doesn't guarantee the cpus in @cpumask stay online | |
191 | * till @fn completes. If some cpus go down in the middle, execution | |
192 | * on the cpu may happen partially or fully on different cpus. @fn | |
193 | * should either be ready for that or the caller should ensure that | |
194 | * the cpus stay online until this function completes. | |
195 | * | |
196 | * All stop_cpus() calls are serialized making it safe for @fn to wait | |
197 | * for all cpus to start executing it. | |
198 | * | |
199 | * CONTEXT: | |
200 | * Might sleep. | |
201 | * | |
202 | * RETURNS: | |
203 | * -ENOENT if @fn(@arg) was not executed at all because all cpus in | |
204 | * @cpumask were offline; otherwise, 0 if all executions of @fn | |
205 | * returned 0, any non zero return value if any returned non zero. | |
206 | */ | |
207 | int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg) | |
208 | { | |
209 | int ret; | |
210 | ||
211 | /* static works are used, process one request at a time */ | |
212 | mutex_lock(&stop_cpus_mutex); | |
213 | ret = __stop_cpus(cpumask, fn, arg); | |
214 | mutex_unlock(&stop_cpus_mutex); | |
215 | return ret; | |
216 | } | |
217 | ||
218 | /** | |
219 | * try_stop_cpus - try to stop multiple cpus | |
220 | * @cpumask: cpus to stop | |
221 | * @fn: function to execute | |
222 | * @arg: argument to @fn | |
223 | * | |
224 | * Identical to stop_cpus() except that it fails with -EAGAIN if | |
225 | * someone else is already using the facility. | |
226 | * | |
227 | * CONTEXT: | |
228 | * Might sleep. | |
229 | * | |
230 | * RETURNS: | |
231 | * -EAGAIN if someone else is already stopping cpus, -ENOENT if | |
232 | * @fn(@arg) was not executed at all because all cpus in @cpumask were | |
233 | * offline; otherwise, 0 if all executions of @fn returned 0, any non | |
234 | * zero return value if any returned non zero. | |
235 | */ | |
236 | int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg) | |
237 | { | |
238 | int ret; | |
239 | ||
240 | /* static works are used, process one request at a time */ | |
241 | if (!mutex_trylock(&stop_cpus_mutex)) | |
242 | return -EAGAIN; | |
243 | ret = __stop_cpus(cpumask, fn, arg); | |
244 | mutex_unlock(&stop_cpus_mutex); | |
245 | return ret; | |
246 | } | |
247 | ||
14e568e7 TG |
248 | static int cpu_stop_should_run(unsigned int cpu) |
249 | { | |
250 | struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); | |
251 | unsigned long flags; | |
252 | int run; | |
253 | ||
254 | spin_lock_irqsave(&stopper->lock, flags); | |
255 | run = !list_empty(&stopper->works); | |
256 | spin_unlock_irqrestore(&stopper->lock, flags); | |
257 | return run; | |
258 | } | |
259 | ||
260 | static void cpu_stopper_thread(unsigned int cpu) | |
1142d810 | 261 | { |
14e568e7 | 262 | struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); |
1142d810 TH |
263 | struct cpu_stop_work *work; |
264 | int ret; | |
265 | ||
266 | repeat: | |
1142d810 TH |
267 | work = NULL; |
268 | spin_lock_irq(&stopper->lock); | |
269 | if (!list_empty(&stopper->works)) { | |
270 | work = list_first_entry(&stopper->works, | |
271 | struct cpu_stop_work, list); | |
272 | list_del_init(&work->list); | |
273 | } | |
274 | spin_unlock_irq(&stopper->lock); | |
275 | ||
276 | if (work) { | |
277 | cpu_stop_fn_t fn = work->fn; | |
278 | void *arg = work->arg; | |
279 | struct cpu_stop_done *done = work->done; | |
ca51c5a7 | 280 | char ksym_buf[KSYM_NAME_LEN] __maybe_unused; |
1142d810 | 281 | |
1142d810 TH |
282 | /* cpu stop callbacks are not allowed to sleep */ |
283 | preempt_disable(); | |
284 | ||
285 | ret = fn(arg); | |
286 | if (ret) | |
287 | done->ret = ret; | |
288 | ||
289 | /* restore preemption and check it's still balanced */ | |
290 | preempt_enable(); | |
291 | WARN_ONCE(preempt_count(), | |
292 | "cpu_stop: %s(%p) leaked preempt count\n", | |
293 | kallsyms_lookup((unsigned long)fn, NULL, NULL, NULL, | |
294 | ksym_buf), arg); | |
295 | ||
296 | cpu_stop_signal_done(done, true); | |
14e568e7 TG |
297 | goto repeat; |
298 | } | |
1142d810 TH |
299 | } |
300 | ||
34f971f6 PZ |
301 | extern void sched_set_stop_task(int cpu, struct task_struct *stop); |
302 | ||
14e568e7 TG |
303 | static void cpu_stop_create(unsigned int cpu) |
304 | { | |
305 | sched_set_stop_task(cpu, per_cpu(cpu_stopper_task, cpu)); | |
306 | } | |
307 | ||
308 | static void cpu_stop_park(unsigned int cpu) | |
1142d810 | 309 | { |
1142d810 | 310 | struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); |
14e568e7 TG |
311 | struct cpu_stop_work *work; |
312 | unsigned long flags; | |
1142d810 | 313 | |
14e568e7 TG |
314 | /* drain remaining works */ |
315 | spin_lock_irqsave(&stopper->lock, flags); | |
316 | list_for_each_entry(work, &stopper->works, list) | |
317 | cpu_stop_signal_done(work->done, false); | |
318 | stopper->enabled = false; | |
319 | spin_unlock_irqrestore(&stopper->lock, flags); | |
320 | } | |
1142d810 | 321 | |
14e568e7 TG |
322 | static void cpu_stop_unpark(unsigned int cpu) |
323 | { | |
324 | struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); | |
325 | ||
326 | spin_lock_irq(&stopper->lock); | |
327 | stopper->enabled = true; | |
328 | spin_unlock_irq(&stopper->lock); | |
1142d810 TH |
329 | } |
330 | ||
14e568e7 TG |
331 | static struct smp_hotplug_thread cpu_stop_threads = { |
332 | .store = &cpu_stopper_task, | |
333 | .thread_should_run = cpu_stop_should_run, | |
334 | .thread_fn = cpu_stopper_thread, | |
335 | .thread_comm = "migration/%u", | |
336 | .create = cpu_stop_create, | |
337 | .setup = cpu_stop_unpark, | |
338 | .park = cpu_stop_park, | |
46c498c2 | 339 | .pre_unpark = cpu_stop_unpark, |
14e568e7 | 340 | .selfparking = true, |
1142d810 TH |
341 | }; |
342 | ||
343 | static int __init cpu_stop_init(void) | |
344 | { | |
1142d810 | 345 | unsigned int cpu; |
1142d810 TH |
346 | |
347 | for_each_possible_cpu(cpu) { | |
348 | struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); | |
349 | ||
350 | spin_lock_init(&stopper->lock); | |
351 | INIT_LIST_HEAD(&stopper->works); | |
352 | } | |
353 | ||
14e568e7 | 354 | BUG_ON(smpboot_register_percpu_thread(&cpu_stop_threads)); |
f445027e | 355 | stop_machine_initialized = true; |
1142d810 TH |
356 | return 0; |
357 | } | |
358 | early_initcall(cpu_stop_init); | |
1da177e4 | 359 | |
bbf1bb3e TH |
360 | #ifdef CONFIG_STOP_MACHINE |
361 | ||
ffdb5976 | 362 | /* This controls the threads on each CPU. */ |
1da177e4 | 363 | enum stopmachine_state { |
ffdb5976 RR |
364 | /* Dummy starting state for thread. */ |
365 | STOPMACHINE_NONE, | |
366 | /* Awaiting everyone to be scheduled. */ | |
1da177e4 | 367 | STOPMACHINE_PREPARE, |
ffdb5976 | 368 | /* Disable interrupts. */ |
1da177e4 | 369 | STOPMACHINE_DISABLE_IRQ, |
ffdb5976 | 370 | /* Run the function */ |
5c2aed62 | 371 | STOPMACHINE_RUN, |
ffdb5976 | 372 | /* Exit */ |
1da177e4 LT |
373 | STOPMACHINE_EXIT, |
374 | }; | |
375 | ||
5c2aed62 | 376 | struct stop_machine_data { |
3fc1f1e2 TH |
377 | int (*fn)(void *); |
378 | void *data; | |
379 | /* Like num_online_cpus(), but hotplug cpu uses us, so we need this. */ | |
380 | unsigned int num_threads; | |
381 | const struct cpumask *active_cpus; | |
382 | ||
383 | enum stopmachine_state state; | |
384 | atomic_t thread_ack; | |
ffdb5976 | 385 | }; |
5c2aed62 | 386 | |
3fc1f1e2 TH |
387 | static void set_state(struct stop_machine_data *smdata, |
388 | enum stopmachine_state newstate) | |
1da177e4 | 389 | { |
ffdb5976 | 390 | /* Reset ack counter. */ |
3fc1f1e2 | 391 | atomic_set(&smdata->thread_ack, smdata->num_threads); |
ffdb5976 | 392 | smp_wmb(); |
3fc1f1e2 | 393 | smdata->state = newstate; |
1da177e4 LT |
394 | } |
395 | ||
ffdb5976 | 396 | /* Last one to ack a state moves to the next state. */ |
3fc1f1e2 | 397 | static void ack_state(struct stop_machine_data *smdata) |
1da177e4 | 398 | { |
3fc1f1e2 TH |
399 | if (atomic_dec_and_test(&smdata->thread_ack)) |
400 | set_state(smdata, smdata->state + 1); | |
1da177e4 LT |
401 | } |
402 | ||
3fc1f1e2 TH |
403 | /* This is the cpu_stop function which stops the CPU. */ |
404 | static int stop_machine_cpu_stop(void *data) | |
1da177e4 | 405 | { |
3fc1f1e2 | 406 | struct stop_machine_data *smdata = data; |
ffdb5976 | 407 | enum stopmachine_state curstate = STOPMACHINE_NONE; |
3fc1f1e2 | 408 | int cpu = smp_processor_id(), err = 0; |
f740e6cd | 409 | unsigned long flags; |
3fc1f1e2 TH |
410 | bool is_active; |
411 | ||
f740e6cd TH |
412 | /* |
413 | * When called from stop_machine_from_inactive_cpu(), irq might | |
414 | * already be disabled. Save the state and restore it on exit. | |
415 | */ | |
416 | local_save_flags(flags); | |
417 | ||
3fc1f1e2 TH |
418 | if (!smdata->active_cpus) |
419 | is_active = cpu == cpumask_first(cpu_online_mask); | |
420 | else | |
421 | is_active = cpumask_test_cpu(cpu, smdata->active_cpus); | |
c9583e55 | 422 | |
ffdb5976 RR |
423 | /* Simple state machine */ |
424 | do { | |
425 | /* Chill out and ensure we re-read stopmachine_state. */ | |
3401a61e | 426 | cpu_relax(); |
3fc1f1e2 TH |
427 | if (smdata->state != curstate) { |
428 | curstate = smdata->state; | |
ffdb5976 RR |
429 | switch (curstate) { |
430 | case STOPMACHINE_DISABLE_IRQ: | |
431 | local_irq_disable(); | |
432 | hard_irq_disable(); | |
433 | break; | |
434 | case STOPMACHINE_RUN: | |
3fc1f1e2 TH |
435 | if (is_active) |
436 | err = smdata->fn(smdata->data); | |
ffdb5976 RR |
437 | break; |
438 | default: | |
439 | break; | |
440 | } | |
3fc1f1e2 | 441 | ack_state(smdata); |
ffdb5976 RR |
442 | } |
443 | } while (curstate != STOPMACHINE_EXIT); | |
1da177e4 | 444 | |
f740e6cd | 445 | local_irq_restore(flags); |
3fc1f1e2 | 446 | return err; |
1da177e4 LT |
447 | } |
448 | ||
41c7bb95 | 449 | int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus) |
1da177e4 | 450 | { |
3fc1f1e2 TH |
451 | struct stop_machine_data smdata = { .fn = fn, .data = data, |
452 | .num_threads = num_online_cpus(), | |
453 | .active_cpus = cpus }; | |
454 | ||
f445027e JF |
455 | if (!stop_machine_initialized) { |
456 | /* | |
457 | * Handle the case where stop_machine() is called | |
458 | * early in boot before stop_machine() has been | |
459 | * initialized. | |
460 | */ | |
461 | unsigned long flags; | |
462 | int ret; | |
463 | ||
464 | WARN_ON_ONCE(smdata.num_threads != 1); | |
465 | ||
466 | local_irq_save(flags); | |
467 | hard_irq_disable(); | |
468 | ret = (*fn)(data); | |
469 | local_irq_restore(flags); | |
470 | ||
471 | return ret; | |
472 | } | |
473 | ||
3fc1f1e2 TH |
474 | /* Set the initial state and stop all online cpus. */ |
475 | set_state(&smdata, STOPMACHINE_PREPARE); | |
476 | return stop_cpus(cpu_online_mask, stop_machine_cpu_stop, &smdata); | |
1da177e4 LT |
477 | } |
478 | ||
41c7bb95 | 479 | int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus) |
1da177e4 | 480 | { |
1da177e4 LT |
481 | int ret; |
482 | ||
483 | /* No CPUs can come up or down during this. */ | |
86ef5c9a | 484 | get_online_cpus(); |
eeec4fad | 485 | ret = __stop_machine(fn, data, cpus); |
86ef5c9a | 486 | put_online_cpus(); |
1da177e4 LT |
487 | return ret; |
488 | } | |
eeec4fad | 489 | EXPORT_SYMBOL_GPL(stop_machine); |
bbf1bb3e | 490 | |
f740e6cd TH |
491 | /** |
492 | * stop_machine_from_inactive_cpu - stop_machine() from inactive CPU | |
493 | * @fn: the function to run | |
494 | * @data: the data ptr for the @fn() | |
495 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu) | |
496 | * | |
497 | * This is identical to stop_machine() but can be called from a CPU which | |
498 | * is not active. The local CPU is in the process of hotplug (so no other | |
499 | * CPU hotplug can start) and not marked active and doesn't have enough | |
500 | * context to sleep. | |
501 | * | |
502 | * This function provides stop_machine() functionality for such state by | |
503 | * using busy-wait for synchronization and executing @fn directly for local | |
504 | * CPU. | |
505 | * | |
506 | * CONTEXT: | |
507 | * Local CPU is inactive. Temporarily stops all active CPUs. | |
508 | * | |
509 | * RETURNS: | |
510 | * 0 if all executions of @fn returned 0, any non zero return value if any | |
511 | * returned non zero. | |
512 | */ | |
513 | int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data, | |
514 | const struct cpumask *cpus) | |
515 | { | |
516 | struct stop_machine_data smdata = { .fn = fn, .data = data, | |
517 | .active_cpus = cpus }; | |
518 | struct cpu_stop_done done; | |
519 | int ret; | |
520 | ||
521 | /* Local CPU must be inactive and CPU hotplug in progress. */ | |
522 | BUG_ON(cpu_active(raw_smp_processor_id())); | |
523 | smdata.num_threads = num_active_cpus() + 1; /* +1 for local */ | |
524 | ||
525 | /* No proper task established and can't sleep - busy wait for lock. */ | |
526 | while (!mutex_trylock(&stop_cpus_mutex)) | |
527 | cpu_relax(); | |
528 | ||
529 | /* Schedule work on other CPUs and execute directly for local CPU */ | |
530 | set_state(&smdata, STOPMACHINE_PREPARE); | |
531 | cpu_stop_init_done(&done, num_active_cpus()); | |
532 | queue_stop_cpus_work(cpu_active_mask, stop_machine_cpu_stop, &smdata, | |
533 | &done); | |
534 | ret = stop_machine_cpu_stop(&smdata); | |
535 | ||
536 | /* Busy wait for completion. */ | |
537 | while (!completion_done(&done.completion)) | |
538 | cpu_relax(); | |
539 | ||
540 | mutex_unlock(&stop_cpus_mutex); | |
541 | return ret ?: done.ret; | |
542 | } | |
543 | ||
bbf1bb3e | 544 | #endif /* CONFIG_STOP_MACHINE */ |