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1 | /* CPU control. | |
2 | * (C) 2001, 2002, 2003, 2004 Rusty Russell | |
3 | * | |
4 | * This code is licenced under the GPL. | |
5 | */ | |
6 | #include <linux/proc_fs.h> | |
7 | #include <linux/smp.h> | |
8 | #include <linux/init.h> | |
9 | #include <linux/notifier.h> | |
10 | #include <linux/sched.h> | |
11 | #include <linux/unistd.h> | |
12 | #include <linux/cpu.h> | |
13 | #include <linux/oom.h> | |
14 | #include <linux/rcupdate.h> | |
15 | #include <linux/export.h> | |
16 | #include <linux/bug.h> | |
17 | #include <linux/kthread.h> | |
18 | #include <linux/stop_machine.h> | |
19 | #include <linux/mutex.h> | |
20 | #include <linux/gfp.h> | |
21 | #include <linux/suspend.h> | |
22 | #include <linux/lockdep.h> | |
23 | #include <linux/tick.h> | |
24 | #include <linux/irq.h> | |
25 | #include <linux/smpboot.h> | |
26 | ||
27 | #include <trace/events/power.h> | |
28 | #define CREATE_TRACE_POINTS | |
29 | #include <trace/events/cpuhp.h> | |
30 | ||
31 | #include "smpboot.h" | |
32 | ||
33 | /** | |
34 | * cpuhp_cpu_state - Per cpu hotplug state storage | |
35 | * @state: The current cpu state | |
36 | * @target: The target state | |
37 | * @thread: Pointer to the hotplug thread | |
38 | * @should_run: Thread should execute | |
39 | * @rollback: Perform a rollback | |
40 | * @cb_stat: The state for a single callback (install/uninstall) | |
41 | * @cb: Single callback function (install/uninstall) | |
42 | * @result: Result of the operation | |
43 | * @done: Signal completion to the issuer of the task | |
44 | */ | |
45 | struct cpuhp_cpu_state { | |
46 | enum cpuhp_state state; | |
47 | enum cpuhp_state target; | |
48 | #ifdef CONFIG_SMP | |
49 | struct task_struct *thread; | |
50 | bool should_run; | |
51 | bool rollback; | |
52 | enum cpuhp_state cb_state; | |
53 | int (*cb)(unsigned int cpu); | |
54 | int result; | |
55 | struct completion done; | |
56 | #endif | |
57 | }; | |
58 | ||
59 | static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state); | |
60 | ||
61 | /** | |
62 | * cpuhp_step - Hotplug state machine step | |
63 | * @name: Name of the step | |
64 | * @startup: Startup function of the step | |
65 | * @teardown: Teardown function of the step | |
66 | * @skip_onerr: Do not invoke the functions on error rollback | |
67 | * Will go away once the notifiers are gone | |
68 | * @cant_stop: Bringup/teardown can't be stopped at this step | |
69 | */ | |
70 | struct cpuhp_step { | |
71 | const char *name; | |
72 | int (*startup)(unsigned int cpu); | |
73 | int (*teardown)(unsigned int cpu); | |
74 | bool skip_onerr; | |
75 | bool cant_stop; | |
76 | }; | |
77 | ||
78 | static DEFINE_MUTEX(cpuhp_state_mutex); | |
79 | static struct cpuhp_step cpuhp_bp_states[]; | |
80 | static struct cpuhp_step cpuhp_ap_states[]; | |
81 | ||
82 | /** | |
83 | * cpuhp_invoke_callback _ Invoke the callbacks for a given state | |
84 | * @cpu: The cpu for which the callback should be invoked | |
85 | * @step: The step in the state machine | |
86 | * @cb: The callback function to invoke | |
87 | * | |
88 | * Called from cpu hotplug and from the state register machinery | |
89 | */ | |
90 | static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state step, | |
91 | int (*cb)(unsigned int)) | |
92 | { | |
93 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
94 | int ret = 0; | |
95 | ||
96 | if (cb) { | |
97 | trace_cpuhp_enter(cpu, st->target, step, cb); | |
98 | ret = cb(cpu); | |
99 | trace_cpuhp_exit(cpu, st->state, step, ret); | |
100 | } | |
101 | return ret; | |
102 | } | |
103 | ||
104 | #ifdef CONFIG_SMP | |
105 | /* Serializes the updates to cpu_online_mask, cpu_present_mask */ | |
106 | static DEFINE_MUTEX(cpu_add_remove_lock); | |
107 | bool cpuhp_tasks_frozen; | |
108 | EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen); | |
109 | ||
110 | /* | |
111 | * The following two APIs (cpu_maps_update_begin/done) must be used when | |
112 | * attempting to serialize the updates to cpu_online_mask & cpu_present_mask. | |
113 | * The APIs cpu_notifier_register_begin/done() must be used to protect CPU | |
114 | * hotplug callback (un)registration performed using __register_cpu_notifier() | |
115 | * or __unregister_cpu_notifier(). | |
116 | */ | |
117 | void cpu_maps_update_begin(void) | |
118 | { | |
119 | mutex_lock(&cpu_add_remove_lock); | |
120 | } | |
121 | EXPORT_SYMBOL(cpu_notifier_register_begin); | |
122 | ||
123 | void cpu_maps_update_done(void) | |
124 | { | |
125 | mutex_unlock(&cpu_add_remove_lock); | |
126 | } | |
127 | EXPORT_SYMBOL(cpu_notifier_register_done); | |
128 | ||
129 | static RAW_NOTIFIER_HEAD(cpu_chain); | |
130 | ||
131 | /* If set, cpu_up and cpu_down will return -EBUSY and do nothing. | |
132 | * Should always be manipulated under cpu_add_remove_lock | |
133 | */ | |
134 | static int cpu_hotplug_disabled; | |
135 | ||
136 | #ifdef CONFIG_HOTPLUG_CPU | |
137 | ||
138 | static struct { | |
139 | struct task_struct *active_writer; | |
140 | /* wait queue to wake up the active_writer */ | |
141 | wait_queue_head_t wq; | |
142 | /* verifies that no writer will get active while readers are active */ | |
143 | struct mutex lock; | |
144 | /* | |
145 | * Also blocks the new readers during | |
146 | * an ongoing cpu hotplug operation. | |
147 | */ | |
148 | atomic_t refcount; | |
149 | ||
150 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
151 | struct lockdep_map dep_map; | |
152 | #endif | |
153 | } cpu_hotplug = { | |
154 | .active_writer = NULL, | |
155 | .wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq), | |
156 | .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock), | |
157 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
158 | .dep_map = {.name = "cpu_hotplug.lock" }, | |
159 | #endif | |
160 | }; | |
161 | ||
162 | /* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */ | |
163 | #define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map) | |
164 | #define cpuhp_lock_acquire_tryread() \ | |
165 | lock_map_acquire_tryread(&cpu_hotplug.dep_map) | |
166 | #define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map) | |
167 | #define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map) | |
168 | ||
169 | ||
170 | void get_online_cpus(void) | |
171 | { | |
172 | might_sleep(); | |
173 | if (cpu_hotplug.active_writer == current) | |
174 | return; | |
175 | cpuhp_lock_acquire_read(); | |
176 | mutex_lock(&cpu_hotplug.lock); | |
177 | atomic_inc(&cpu_hotplug.refcount); | |
178 | mutex_unlock(&cpu_hotplug.lock); | |
179 | } | |
180 | EXPORT_SYMBOL_GPL(get_online_cpus); | |
181 | ||
182 | void put_online_cpus(void) | |
183 | { | |
184 | int refcount; | |
185 | ||
186 | if (cpu_hotplug.active_writer == current) | |
187 | return; | |
188 | ||
189 | refcount = atomic_dec_return(&cpu_hotplug.refcount); | |
190 | if (WARN_ON(refcount < 0)) /* try to fix things up */ | |
191 | atomic_inc(&cpu_hotplug.refcount); | |
192 | ||
193 | if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq)) | |
194 | wake_up(&cpu_hotplug.wq); | |
195 | ||
196 | cpuhp_lock_release(); | |
197 | ||
198 | } | |
199 | EXPORT_SYMBOL_GPL(put_online_cpus); | |
200 | ||
201 | /* | |
202 | * This ensures that the hotplug operation can begin only when the | |
203 | * refcount goes to zero. | |
204 | * | |
205 | * Note that during a cpu-hotplug operation, the new readers, if any, | |
206 | * will be blocked by the cpu_hotplug.lock | |
207 | * | |
208 | * Since cpu_hotplug_begin() is always called after invoking | |
209 | * cpu_maps_update_begin(), we can be sure that only one writer is active. | |
210 | * | |
211 | * Note that theoretically, there is a possibility of a livelock: | |
212 | * - Refcount goes to zero, last reader wakes up the sleeping | |
213 | * writer. | |
214 | * - Last reader unlocks the cpu_hotplug.lock. | |
215 | * - A new reader arrives at this moment, bumps up the refcount. | |
216 | * - The writer acquires the cpu_hotplug.lock finds the refcount | |
217 | * non zero and goes to sleep again. | |
218 | * | |
219 | * However, this is very difficult to achieve in practice since | |
220 | * get_online_cpus() not an api which is called all that often. | |
221 | * | |
222 | */ | |
223 | void cpu_hotplug_begin(void) | |
224 | { | |
225 | DEFINE_WAIT(wait); | |
226 | ||
227 | cpu_hotplug.active_writer = current; | |
228 | cpuhp_lock_acquire(); | |
229 | ||
230 | for (;;) { | |
231 | mutex_lock(&cpu_hotplug.lock); | |
232 | prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE); | |
233 | if (likely(!atomic_read(&cpu_hotplug.refcount))) | |
234 | break; | |
235 | mutex_unlock(&cpu_hotplug.lock); | |
236 | schedule(); | |
237 | } | |
238 | finish_wait(&cpu_hotplug.wq, &wait); | |
239 | } | |
240 | ||
241 | void cpu_hotplug_done(void) | |
242 | { | |
243 | cpu_hotplug.active_writer = NULL; | |
244 | mutex_unlock(&cpu_hotplug.lock); | |
245 | cpuhp_lock_release(); | |
246 | } | |
247 | ||
248 | /* | |
249 | * Wait for currently running CPU hotplug operations to complete (if any) and | |
250 | * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects | |
251 | * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the | |
252 | * hotplug path before performing hotplug operations. So acquiring that lock | |
253 | * guarantees mutual exclusion from any currently running hotplug operations. | |
254 | */ | |
255 | void cpu_hotplug_disable(void) | |
256 | { | |
257 | cpu_maps_update_begin(); | |
258 | cpu_hotplug_disabled++; | |
259 | cpu_maps_update_done(); | |
260 | } | |
261 | EXPORT_SYMBOL_GPL(cpu_hotplug_disable); | |
262 | ||
263 | void cpu_hotplug_enable(void) | |
264 | { | |
265 | cpu_maps_update_begin(); | |
266 | WARN_ON(--cpu_hotplug_disabled < 0); | |
267 | cpu_maps_update_done(); | |
268 | } | |
269 | EXPORT_SYMBOL_GPL(cpu_hotplug_enable); | |
270 | #endif /* CONFIG_HOTPLUG_CPU */ | |
271 | ||
272 | /* Need to know about CPUs going up/down? */ | |
273 | int register_cpu_notifier(struct notifier_block *nb) | |
274 | { | |
275 | int ret; | |
276 | cpu_maps_update_begin(); | |
277 | ret = raw_notifier_chain_register(&cpu_chain, nb); | |
278 | cpu_maps_update_done(); | |
279 | return ret; | |
280 | } | |
281 | ||
282 | int __register_cpu_notifier(struct notifier_block *nb) | |
283 | { | |
284 | return raw_notifier_chain_register(&cpu_chain, nb); | |
285 | } | |
286 | ||
287 | static int __cpu_notify(unsigned long val, unsigned int cpu, int nr_to_call, | |
288 | int *nr_calls) | |
289 | { | |
290 | unsigned long mod = cpuhp_tasks_frozen ? CPU_TASKS_FROZEN : 0; | |
291 | void *hcpu = (void *)(long)cpu; | |
292 | ||
293 | int ret; | |
294 | ||
295 | ret = __raw_notifier_call_chain(&cpu_chain, val | mod, hcpu, nr_to_call, | |
296 | nr_calls); | |
297 | ||
298 | return notifier_to_errno(ret); | |
299 | } | |
300 | ||
301 | static int cpu_notify(unsigned long val, unsigned int cpu) | |
302 | { | |
303 | return __cpu_notify(val, cpu, -1, NULL); | |
304 | } | |
305 | ||
306 | static void cpu_notify_nofail(unsigned long val, unsigned int cpu) | |
307 | { | |
308 | BUG_ON(cpu_notify(val, cpu)); | |
309 | } | |
310 | ||
311 | /* Notifier wrappers for transitioning to state machine */ | |
312 | static int notify_prepare(unsigned int cpu) | |
313 | { | |
314 | int nr_calls = 0; | |
315 | int ret; | |
316 | ||
317 | ret = __cpu_notify(CPU_UP_PREPARE, cpu, -1, &nr_calls); | |
318 | if (ret) { | |
319 | nr_calls--; | |
320 | printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n", | |
321 | __func__, cpu); | |
322 | __cpu_notify(CPU_UP_CANCELED, cpu, nr_calls, NULL); | |
323 | } | |
324 | return ret; | |
325 | } | |
326 | ||
327 | static int notify_online(unsigned int cpu) | |
328 | { | |
329 | cpu_notify(CPU_ONLINE, cpu); | |
330 | return 0; | |
331 | } | |
332 | ||
333 | static int notify_starting(unsigned int cpu) | |
334 | { | |
335 | cpu_notify(CPU_STARTING, cpu); | |
336 | return 0; | |
337 | } | |
338 | ||
339 | static int bringup_wait_for_ap(unsigned int cpu) | |
340 | { | |
341 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
342 | ||
343 | wait_for_completion(&st->done); | |
344 | return st->result; | |
345 | } | |
346 | ||
347 | static int bringup_cpu(unsigned int cpu) | |
348 | { | |
349 | struct task_struct *idle = idle_thread_get(cpu); | |
350 | int ret; | |
351 | ||
352 | /* Arch-specific enabling code. */ | |
353 | ret = __cpu_up(cpu, idle); | |
354 | if (ret) { | |
355 | cpu_notify(CPU_UP_CANCELED, cpu); | |
356 | return ret; | |
357 | } | |
358 | ret = bringup_wait_for_ap(cpu); | |
359 | BUG_ON(!cpu_online(cpu)); | |
360 | return ret; | |
361 | } | |
362 | ||
363 | /* | |
364 | * Hotplug state machine related functions | |
365 | */ | |
366 | static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st, | |
367 | struct cpuhp_step *steps) | |
368 | { | |
369 | for (st->state++; st->state < st->target; st->state++) { | |
370 | struct cpuhp_step *step = steps + st->state; | |
371 | ||
372 | if (!step->skip_onerr) | |
373 | cpuhp_invoke_callback(cpu, st->state, step->startup); | |
374 | } | |
375 | } | |
376 | ||
377 | static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, | |
378 | struct cpuhp_step *steps, enum cpuhp_state target) | |
379 | { | |
380 | enum cpuhp_state prev_state = st->state; | |
381 | int ret = 0; | |
382 | ||
383 | for (; st->state > target; st->state--) { | |
384 | struct cpuhp_step *step = steps + st->state; | |
385 | ||
386 | ret = cpuhp_invoke_callback(cpu, st->state, step->teardown); | |
387 | if (ret) { | |
388 | st->target = prev_state; | |
389 | undo_cpu_down(cpu, st, steps); | |
390 | break; | |
391 | } | |
392 | } | |
393 | return ret; | |
394 | } | |
395 | ||
396 | static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st, | |
397 | struct cpuhp_step *steps) | |
398 | { | |
399 | for (st->state--; st->state > st->target; st->state--) { | |
400 | struct cpuhp_step *step = steps + st->state; | |
401 | ||
402 | if (!step->skip_onerr) | |
403 | cpuhp_invoke_callback(cpu, st->state, step->teardown); | |
404 | } | |
405 | } | |
406 | ||
407 | static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, | |
408 | struct cpuhp_step *steps, enum cpuhp_state target) | |
409 | { | |
410 | enum cpuhp_state prev_state = st->state; | |
411 | int ret = 0; | |
412 | ||
413 | while (st->state < target) { | |
414 | struct cpuhp_step *step; | |
415 | ||
416 | st->state++; | |
417 | step = steps + st->state; | |
418 | ret = cpuhp_invoke_callback(cpu, st->state, step->startup); | |
419 | if (ret) { | |
420 | st->target = prev_state; | |
421 | undo_cpu_up(cpu, st, steps); | |
422 | break; | |
423 | } | |
424 | } | |
425 | return ret; | |
426 | } | |
427 | ||
428 | /* | |
429 | * The cpu hotplug threads manage the bringup and teardown of the cpus | |
430 | */ | |
431 | static void cpuhp_create(unsigned int cpu) | |
432 | { | |
433 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
434 | ||
435 | init_completion(&st->done); | |
436 | } | |
437 | ||
438 | static int cpuhp_should_run(unsigned int cpu) | |
439 | { | |
440 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); | |
441 | ||
442 | return st->should_run; | |
443 | } | |
444 | ||
445 | /* Execute the teardown callbacks. Used to be CPU_DOWN_PREPARE */ | |
446 | static int cpuhp_ap_offline(unsigned int cpu, struct cpuhp_cpu_state *st) | |
447 | { | |
448 | enum cpuhp_state target = max((int)st->target, CPUHP_TEARDOWN_CPU); | |
449 | ||
450 | return cpuhp_down_callbacks(cpu, st, cpuhp_ap_states, target); | |
451 | } | |
452 | ||
453 | /* Execute the online startup callbacks. Used to be CPU_ONLINE */ | |
454 | static int cpuhp_ap_online(unsigned int cpu, struct cpuhp_cpu_state *st) | |
455 | { | |
456 | return cpuhp_up_callbacks(cpu, st, cpuhp_ap_states, st->target); | |
457 | } | |
458 | ||
459 | /* | |
460 | * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke | |
461 | * callbacks when a state gets [un]installed at runtime. | |
462 | */ | |
463 | static void cpuhp_thread_fun(unsigned int cpu) | |
464 | { | |
465 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); | |
466 | int ret = 0; | |
467 | ||
468 | /* | |
469 | * Paired with the mb() in cpuhp_kick_ap_work and | |
470 | * cpuhp_invoke_ap_callback, so the work set is consistent visible. | |
471 | */ | |
472 | smp_mb(); | |
473 | if (!st->should_run) | |
474 | return; | |
475 | ||
476 | st->should_run = false; | |
477 | ||
478 | /* Single callback invocation for [un]install ? */ | |
479 | if (st->cb) { | |
480 | if (st->cb_state < CPUHP_AP_ONLINE) { | |
481 | local_irq_disable(); | |
482 | ret = cpuhp_invoke_callback(cpu, st->cb_state, st->cb); | |
483 | local_irq_enable(); | |
484 | } else { | |
485 | ret = cpuhp_invoke_callback(cpu, st->cb_state, st->cb); | |
486 | } | |
487 | } else if (st->rollback) { | |
488 | BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE); | |
489 | ||
490 | undo_cpu_down(cpu, st, cpuhp_ap_states); | |
491 | /* | |
492 | * This is a momentary workaround to keep the notifier users | |
493 | * happy. Will go away once we got rid of the notifiers. | |
494 | */ | |
495 | cpu_notify_nofail(CPU_DOWN_FAILED, cpu); | |
496 | st->rollback = false; | |
497 | } else { | |
498 | /* Cannot happen .... */ | |
499 | BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE); | |
500 | ||
501 | /* Regular hotplug work */ | |
502 | if (st->state < st->target) | |
503 | ret = cpuhp_ap_online(cpu, st); | |
504 | else if (st->state > st->target) | |
505 | ret = cpuhp_ap_offline(cpu, st); | |
506 | } | |
507 | st->result = ret; | |
508 | complete(&st->done); | |
509 | } | |
510 | ||
511 | /* Invoke a single callback on a remote cpu */ | |
512 | static int cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, | |
513 | int (*cb)(unsigned int)) | |
514 | { | |
515 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
516 | ||
517 | if (!cpu_online(cpu)) | |
518 | return 0; | |
519 | ||
520 | /* | |
521 | * If we are up and running, use the hotplug thread. For early calls | |
522 | * we invoke the thread function directly. | |
523 | */ | |
524 | if (!st->thread) | |
525 | return cpuhp_invoke_callback(cpu, state, cb); | |
526 | ||
527 | st->cb_state = state; | |
528 | st->cb = cb; | |
529 | /* | |
530 | * Make sure the above stores are visible before should_run becomes | |
531 | * true. Paired with the mb() above in cpuhp_thread_fun() | |
532 | */ | |
533 | smp_mb(); | |
534 | st->should_run = true; | |
535 | wake_up_process(st->thread); | |
536 | wait_for_completion(&st->done); | |
537 | return st->result; | |
538 | } | |
539 | ||
540 | /* Regular hotplug invocation of the AP hotplug thread */ | |
541 | static void __cpuhp_kick_ap_work(struct cpuhp_cpu_state *st) | |
542 | { | |
543 | st->result = 0; | |
544 | st->cb = NULL; | |
545 | /* | |
546 | * Make sure the above stores are visible before should_run becomes | |
547 | * true. Paired with the mb() above in cpuhp_thread_fun() | |
548 | */ | |
549 | smp_mb(); | |
550 | st->should_run = true; | |
551 | wake_up_process(st->thread); | |
552 | } | |
553 | ||
554 | static int cpuhp_kick_ap_work(unsigned int cpu) | |
555 | { | |
556 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
557 | enum cpuhp_state state = st->state; | |
558 | ||
559 | trace_cpuhp_enter(cpu, st->target, state, cpuhp_kick_ap_work); | |
560 | __cpuhp_kick_ap_work(st); | |
561 | wait_for_completion(&st->done); | |
562 | trace_cpuhp_exit(cpu, st->state, state, st->result); | |
563 | return st->result; | |
564 | } | |
565 | ||
566 | static struct smp_hotplug_thread cpuhp_threads = { | |
567 | .store = &cpuhp_state.thread, | |
568 | .create = &cpuhp_create, | |
569 | .thread_should_run = cpuhp_should_run, | |
570 | .thread_fn = cpuhp_thread_fun, | |
571 | .thread_comm = "cpuhp/%u", | |
572 | .selfparking = true, | |
573 | }; | |
574 | ||
575 | void __init cpuhp_threads_init(void) | |
576 | { | |
577 | BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads)); | |
578 | kthread_unpark(this_cpu_read(cpuhp_state.thread)); | |
579 | } | |
580 | ||
581 | #ifdef CONFIG_HOTPLUG_CPU | |
582 | EXPORT_SYMBOL(register_cpu_notifier); | |
583 | EXPORT_SYMBOL(__register_cpu_notifier); | |
584 | void unregister_cpu_notifier(struct notifier_block *nb) | |
585 | { | |
586 | cpu_maps_update_begin(); | |
587 | raw_notifier_chain_unregister(&cpu_chain, nb); | |
588 | cpu_maps_update_done(); | |
589 | } | |
590 | EXPORT_SYMBOL(unregister_cpu_notifier); | |
591 | ||
592 | void __unregister_cpu_notifier(struct notifier_block *nb) | |
593 | { | |
594 | raw_notifier_chain_unregister(&cpu_chain, nb); | |
595 | } | |
596 | EXPORT_SYMBOL(__unregister_cpu_notifier); | |
597 | ||
598 | /** | |
599 | * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU | |
600 | * @cpu: a CPU id | |
601 | * | |
602 | * This function walks all processes, finds a valid mm struct for each one and | |
603 | * then clears a corresponding bit in mm's cpumask. While this all sounds | |
604 | * trivial, there are various non-obvious corner cases, which this function | |
605 | * tries to solve in a safe manner. | |
606 | * | |
607 | * Also note that the function uses a somewhat relaxed locking scheme, so it may | |
608 | * be called only for an already offlined CPU. | |
609 | */ | |
610 | void clear_tasks_mm_cpumask(int cpu) | |
611 | { | |
612 | struct task_struct *p; | |
613 | ||
614 | /* | |
615 | * This function is called after the cpu is taken down and marked | |
616 | * offline, so its not like new tasks will ever get this cpu set in | |
617 | * their mm mask. -- Peter Zijlstra | |
618 | * Thus, we may use rcu_read_lock() here, instead of grabbing | |
619 | * full-fledged tasklist_lock. | |
620 | */ | |
621 | WARN_ON(cpu_online(cpu)); | |
622 | rcu_read_lock(); | |
623 | for_each_process(p) { | |
624 | struct task_struct *t; | |
625 | ||
626 | /* | |
627 | * Main thread might exit, but other threads may still have | |
628 | * a valid mm. Find one. | |
629 | */ | |
630 | t = find_lock_task_mm(p); | |
631 | if (!t) | |
632 | continue; | |
633 | cpumask_clear_cpu(cpu, mm_cpumask(t->mm)); | |
634 | task_unlock(t); | |
635 | } | |
636 | rcu_read_unlock(); | |
637 | } | |
638 | ||
639 | static inline void check_for_tasks(int dead_cpu) | |
640 | { | |
641 | struct task_struct *g, *p; | |
642 | ||
643 | read_lock(&tasklist_lock); | |
644 | for_each_process_thread(g, p) { | |
645 | if (!p->on_rq) | |
646 | continue; | |
647 | /* | |
648 | * We do the check with unlocked task_rq(p)->lock. | |
649 | * Order the reading to do not warn about a task, | |
650 | * which was running on this cpu in the past, and | |
651 | * it's just been woken on another cpu. | |
652 | */ | |
653 | rmb(); | |
654 | if (task_cpu(p) != dead_cpu) | |
655 | continue; | |
656 | ||
657 | pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n", | |
658 | p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags); | |
659 | } | |
660 | read_unlock(&tasklist_lock); | |
661 | } | |
662 | ||
663 | static int notify_down_prepare(unsigned int cpu) | |
664 | { | |
665 | int err, nr_calls = 0; | |
666 | ||
667 | err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls); | |
668 | if (err) { | |
669 | nr_calls--; | |
670 | __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL); | |
671 | pr_warn("%s: attempt to take down CPU %u failed\n", | |
672 | __func__, cpu); | |
673 | } | |
674 | return err; | |
675 | } | |
676 | ||
677 | static int notify_dying(unsigned int cpu) | |
678 | { | |
679 | cpu_notify(CPU_DYING, cpu); | |
680 | return 0; | |
681 | } | |
682 | ||
683 | /* Take this CPU down. */ | |
684 | static int take_cpu_down(void *_param) | |
685 | { | |
686 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); | |
687 | enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE); | |
688 | int err, cpu = smp_processor_id(); | |
689 | ||
690 | /* Ensure this CPU doesn't handle any more interrupts. */ | |
691 | err = __cpu_disable(); | |
692 | if (err < 0) | |
693 | return err; | |
694 | ||
695 | /* Invoke the former CPU_DYING callbacks */ | |
696 | for (; st->state > target; st->state--) { | |
697 | struct cpuhp_step *step = cpuhp_ap_states + st->state; | |
698 | ||
699 | cpuhp_invoke_callback(cpu, st->state, step->teardown); | |
700 | } | |
701 | /* Give up timekeeping duties */ | |
702 | tick_handover_do_timer(); | |
703 | /* Park the stopper thread */ | |
704 | stop_machine_park(cpu); | |
705 | return 0; | |
706 | } | |
707 | ||
708 | static int takedown_cpu(unsigned int cpu) | |
709 | { | |
710 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
711 | int err; | |
712 | ||
713 | /* Park the smpboot threads */ | |
714 | kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread); | |
715 | smpboot_park_threads(cpu); | |
716 | ||
717 | /* | |
718 | * Prevent irq alloc/free while the dying cpu reorganizes the | |
719 | * interrupt affinities. | |
720 | */ | |
721 | irq_lock_sparse(); | |
722 | ||
723 | /* | |
724 | * So now all preempt/rcu users must observe !cpu_active(). | |
725 | */ | |
726 | err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu)); | |
727 | if (err) { | |
728 | /* CPU refused to die */ | |
729 | irq_unlock_sparse(); | |
730 | /* Unpark the hotplug thread so we can rollback there */ | |
731 | kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread); | |
732 | return err; | |
733 | } | |
734 | BUG_ON(cpu_online(cpu)); | |
735 | ||
736 | /* | |
737 | * The migration_call() CPU_DYING callback will have removed all | |
738 | * runnable tasks from the cpu, there's only the idle task left now | |
739 | * that the migration thread is done doing the stop_machine thing. | |
740 | * | |
741 | * Wait for the stop thread to go away. | |
742 | */ | |
743 | wait_for_completion(&st->done); | |
744 | BUG_ON(st->state != CPUHP_AP_IDLE_DEAD); | |
745 | ||
746 | /* Interrupts are moved away from the dying cpu, reenable alloc/free */ | |
747 | irq_unlock_sparse(); | |
748 | ||
749 | hotplug_cpu__broadcast_tick_pull(cpu); | |
750 | /* This actually kills the CPU. */ | |
751 | __cpu_die(cpu); | |
752 | ||
753 | tick_cleanup_dead_cpu(cpu); | |
754 | return 0; | |
755 | } | |
756 | ||
757 | static int notify_dead(unsigned int cpu) | |
758 | { | |
759 | cpu_notify_nofail(CPU_DEAD, cpu); | |
760 | check_for_tasks(cpu); | |
761 | return 0; | |
762 | } | |
763 | ||
764 | static void cpuhp_complete_idle_dead(void *arg) | |
765 | { | |
766 | struct cpuhp_cpu_state *st = arg; | |
767 | ||
768 | complete(&st->done); | |
769 | } | |
770 | ||
771 | void cpuhp_report_idle_dead(void) | |
772 | { | |
773 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); | |
774 | ||
775 | BUG_ON(st->state != CPUHP_AP_OFFLINE); | |
776 | rcu_report_dead(smp_processor_id()); | |
777 | st->state = CPUHP_AP_IDLE_DEAD; | |
778 | /* | |
779 | * We cannot call complete after rcu_report_dead() so we delegate it | |
780 | * to an online cpu. | |
781 | */ | |
782 | smp_call_function_single(cpumask_first(cpu_online_mask), | |
783 | cpuhp_complete_idle_dead, st, 0); | |
784 | } | |
785 | ||
786 | #else | |
787 | #define notify_down_prepare NULL | |
788 | #define takedown_cpu NULL | |
789 | #define notify_dead NULL | |
790 | #define notify_dying NULL | |
791 | #endif | |
792 | ||
793 | #ifdef CONFIG_HOTPLUG_CPU | |
794 | ||
795 | /* Requires cpu_add_remove_lock to be held */ | |
796 | static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, | |
797 | enum cpuhp_state target) | |
798 | { | |
799 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
800 | int prev_state, ret = 0; | |
801 | bool hasdied = false; | |
802 | ||
803 | if (num_online_cpus() == 1) | |
804 | return -EBUSY; | |
805 | ||
806 | if (!cpu_present(cpu)) | |
807 | return -EINVAL; | |
808 | ||
809 | cpu_hotplug_begin(); | |
810 | ||
811 | cpuhp_tasks_frozen = tasks_frozen; | |
812 | ||
813 | prev_state = st->state; | |
814 | st->target = target; | |
815 | /* | |
816 | * If the current CPU state is in the range of the AP hotplug thread, | |
817 | * then we need to kick the thread. | |
818 | */ | |
819 | if (st->state > CPUHP_TEARDOWN_CPU) { | |
820 | ret = cpuhp_kick_ap_work(cpu); | |
821 | /* | |
822 | * The AP side has done the error rollback already. Just | |
823 | * return the error code.. | |
824 | */ | |
825 | if (ret) | |
826 | goto out; | |
827 | ||
828 | /* | |
829 | * We might have stopped still in the range of the AP hotplug | |
830 | * thread. Nothing to do anymore. | |
831 | */ | |
832 | if (st->state > CPUHP_TEARDOWN_CPU) | |
833 | goto out; | |
834 | } | |
835 | /* | |
836 | * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need | |
837 | * to do the further cleanups. | |
838 | */ | |
839 | ret = cpuhp_down_callbacks(cpu, st, cpuhp_bp_states, target); | |
840 | if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) { | |
841 | st->target = prev_state; | |
842 | st->rollback = true; | |
843 | cpuhp_kick_ap_work(cpu); | |
844 | } | |
845 | ||
846 | hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE; | |
847 | out: | |
848 | cpu_hotplug_done(); | |
849 | /* This post dead nonsense must die */ | |
850 | if (!ret && hasdied) | |
851 | cpu_notify_nofail(CPU_POST_DEAD, cpu); | |
852 | return ret; | |
853 | } | |
854 | ||
855 | static int do_cpu_down(unsigned int cpu, enum cpuhp_state target) | |
856 | { | |
857 | int err; | |
858 | ||
859 | cpu_maps_update_begin(); | |
860 | ||
861 | if (cpu_hotplug_disabled) { | |
862 | err = -EBUSY; | |
863 | goto out; | |
864 | } | |
865 | ||
866 | err = _cpu_down(cpu, 0, target); | |
867 | ||
868 | out: | |
869 | cpu_maps_update_done(); | |
870 | return err; | |
871 | } | |
872 | int cpu_down(unsigned int cpu) | |
873 | { | |
874 | return do_cpu_down(cpu, CPUHP_OFFLINE); | |
875 | } | |
876 | EXPORT_SYMBOL(cpu_down); | |
877 | #endif /*CONFIG_HOTPLUG_CPU*/ | |
878 | ||
879 | /** | |
880 | * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers | |
881 | * @cpu: cpu that just started | |
882 | * | |
883 | * This function calls the cpu_chain notifiers with CPU_STARTING. | |
884 | * It must be called by the arch code on the new cpu, before the new cpu | |
885 | * enables interrupts and before the "boot" cpu returns from __cpu_up(). | |
886 | */ | |
887 | void notify_cpu_starting(unsigned int cpu) | |
888 | { | |
889 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
890 | enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE); | |
891 | ||
892 | while (st->state < target) { | |
893 | struct cpuhp_step *step; | |
894 | ||
895 | st->state++; | |
896 | step = cpuhp_ap_states + st->state; | |
897 | cpuhp_invoke_callback(cpu, st->state, step->startup); | |
898 | } | |
899 | } | |
900 | ||
901 | /* | |
902 | * Called from the idle task. We need to set active here, so we can kick off | |
903 | * the stopper thread and unpark the smpboot threads. If the target state is | |
904 | * beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the | |
905 | * cpu further. | |
906 | */ | |
907 | void cpuhp_online_idle(enum cpuhp_state state) | |
908 | { | |
909 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); | |
910 | unsigned int cpu = smp_processor_id(); | |
911 | ||
912 | /* Happens for the boot cpu */ | |
913 | if (state != CPUHP_AP_ONLINE_IDLE) | |
914 | return; | |
915 | ||
916 | st->state = CPUHP_AP_ONLINE_IDLE; | |
917 | ||
918 | /* Unpark the stopper thread and the hotplug thread of this cpu */ | |
919 | stop_machine_unpark(cpu); | |
920 | kthread_unpark(st->thread); | |
921 | ||
922 | /* Should we go further up ? */ | |
923 | if (st->target > CPUHP_AP_ONLINE_IDLE) | |
924 | __cpuhp_kick_ap_work(st); | |
925 | else | |
926 | complete(&st->done); | |
927 | } | |
928 | ||
929 | /* Requires cpu_add_remove_lock to be held */ | |
930 | static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) | |
931 | { | |
932 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
933 | struct task_struct *idle; | |
934 | int ret = 0; | |
935 | ||
936 | cpu_hotplug_begin(); | |
937 | ||
938 | if (!cpu_present(cpu)) { | |
939 | ret = -EINVAL; | |
940 | goto out; | |
941 | } | |
942 | ||
943 | /* | |
944 | * The caller of do_cpu_up might have raced with another | |
945 | * caller. Ignore it for now. | |
946 | */ | |
947 | if (st->state >= target) | |
948 | goto out; | |
949 | ||
950 | if (st->state == CPUHP_OFFLINE) { | |
951 | /* Let it fail before we try to bring the cpu up */ | |
952 | idle = idle_thread_get(cpu); | |
953 | if (IS_ERR(idle)) { | |
954 | ret = PTR_ERR(idle); | |
955 | goto out; | |
956 | } | |
957 | } | |
958 | ||
959 | cpuhp_tasks_frozen = tasks_frozen; | |
960 | ||
961 | st->target = target; | |
962 | /* | |
963 | * If the current CPU state is in the range of the AP hotplug thread, | |
964 | * then we need to kick the thread once more. | |
965 | */ | |
966 | if (st->state > CPUHP_BRINGUP_CPU) { | |
967 | ret = cpuhp_kick_ap_work(cpu); | |
968 | /* | |
969 | * The AP side has done the error rollback already. Just | |
970 | * return the error code.. | |
971 | */ | |
972 | if (ret) | |
973 | goto out; | |
974 | } | |
975 | ||
976 | /* | |
977 | * Try to reach the target state. We max out on the BP at | |
978 | * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is | |
979 | * responsible for bringing it up to the target state. | |
980 | */ | |
981 | target = min((int)target, CPUHP_BRINGUP_CPU); | |
982 | ret = cpuhp_up_callbacks(cpu, st, cpuhp_bp_states, target); | |
983 | out: | |
984 | cpu_hotplug_done(); | |
985 | return ret; | |
986 | } | |
987 | ||
988 | static int do_cpu_up(unsigned int cpu, enum cpuhp_state target) | |
989 | { | |
990 | int err = 0; | |
991 | ||
992 | if (!cpu_possible(cpu)) { | |
993 | pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n", | |
994 | cpu); | |
995 | #if defined(CONFIG_IA64) | |
996 | pr_err("please check additional_cpus= boot parameter\n"); | |
997 | #endif | |
998 | return -EINVAL; | |
999 | } | |
1000 | ||
1001 | err = try_online_node(cpu_to_node(cpu)); | |
1002 | if (err) | |
1003 | return err; | |
1004 | ||
1005 | cpu_maps_update_begin(); | |
1006 | ||
1007 | if (cpu_hotplug_disabled) { | |
1008 | err = -EBUSY; | |
1009 | goto out; | |
1010 | } | |
1011 | ||
1012 | err = _cpu_up(cpu, 0, target); | |
1013 | out: | |
1014 | cpu_maps_update_done(); | |
1015 | return err; | |
1016 | } | |
1017 | ||
1018 | int cpu_up(unsigned int cpu) | |
1019 | { | |
1020 | return do_cpu_up(cpu, CPUHP_ONLINE); | |
1021 | } | |
1022 | EXPORT_SYMBOL_GPL(cpu_up); | |
1023 | ||
1024 | #ifdef CONFIG_PM_SLEEP_SMP | |
1025 | static cpumask_var_t frozen_cpus; | |
1026 | ||
1027 | int disable_nonboot_cpus(void) | |
1028 | { | |
1029 | int cpu, first_cpu, error = 0; | |
1030 | ||
1031 | cpu_maps_update_begin(); | |
1032 | first_cpu = cpumask_first(cpu_online_mask); | |
1033 | /* | |
1034 | * We take down all of the non-boot CPUs in one shot to avoid races | |
1035 | * with the userspace trying to use the CPU hotplug at the same time | |
1036 | */ | |
1037 | cpumask_clear(frozen_cpus); | |
1038 | ||
1039 | pr_info("Disabling non-boot CPUs ...\n"); | |
1040 | for_each_online_cpu(cpu) { | |
1041 | if (cpu == first_cpu) | |
1042 | continue; | |
1043 | trace_suspend_resume(TPS("CPU_OFF"), cpu, true); | |
1044 | error = _cpu_down(cpu, 1, CPUHP_OFFLINE); | |
1045 | trace_suspend_resume(TPS("CPU_OFF"), cpu, false); | |
1046 | if (!error) | |
1047 | cpumask_set_cpu(cpu, frozen_cpus); | |
1048 | else { | |
1049 | pr_err("Error taking CPU%d down: %d\n", cpu, error); | |
1050 | break; | |
1051 | } | |
1052 | } | |
1053 | ||
1054 | if (!error) | |
1055 | BUG_ON(num_online_cpus() > 1); | |
1056 | else | |
1057 | pr_err("Non-boot CPUs are not disabled\n"); | |
1058 | ||
1059 | /* | |
1060 | * Make sure the CPUs won't be enabled by someone else. We need to do | |
1061 | * this even in case of failure as all disable_nonboot_cpus() users are | |
1062 | * supposed to do enable_nonboot_cpus() on the failure path. | |
1063 | */ | |
1064 | cpu_hotplug_disabled++; | |
1065 | ||
1066 | cpu_maps_update_done(); | |
1067 | return error; | |
1068 | } | |
1069 | ||
1070 | void __weak arch_enable_nonboot_cpus_begin(void) | |
1071 | { | |
1072 | } | |
1073 | ||
1074 | void __weak arch_enable_nonboot_cpus_end(void) | |
1075 | { | |
1076 | } | |
1077 | ||
1078 | void enable_nonboot_cpus(void) | |
1079 | { | |
1080 | int cpu, error; | |
1081 | ||
1082 | /* Allow everyone to use the CPU hotplug again */ | |
1083 | cpu_maps_update_begin(); | |
1084 | WARN_ON(--cpu_hotplug_disabled < 0); | |
1085 | if (cpumask_empty(frozen_cpus)) | |
1086 | goto out; | |
1087 | ||
1088 | pr_info("Enabling non-boot CPUs ...\n"); | |
1089 | ||
1090 | arch_enable_nonboot_cpus_begin(); | |
1091 | ||
1092 | for_each_cpu(cpu, frozen_cpus) { | |
1093 | trace_suspend_resume(TPS("CPU_ON"), cpu, true); | |
1094 | error = _cpu_up(cpu, 1, CPUHP_ONLINE); | |
1095 | trace_suspend_resume(TPS("CPU_ON"), cpu, false); | |
1096 | if (!error) { | |
1097 | pr_info("CPU%d is up\n", cpu); | |
1098 | continue; | |
1099 | } | |
1100 | pr_warn("Error taking CPU%d up: %d\n", cpu, error); | |
1101 | } | |
1102 | ||
1103 | arch_enable_nonboot_cpus_end(); | |
1104 | ||
1105 | cpumask_clear(frozen_cpus); | |
1106 | out: | |
1107 | cpu_maps_update_done(); | |
1108 | } | |
1109 | ||
1110 | static int __init alloc_frozen_cpus(void) | |
1111 | { | |
1112 | if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO)) | |
1113 | return -ENOMEM; | |
1114 | return 0; | |
1115 | } | |
1116 | core_initcall(alloc_frozen_cpus); | |
1117 | ||
1118 | /* | |
1119 | * When callbacks for CPU hotplug notifications are being executed, we must | |
1120 | * ensure that the state of the system with respect to the tasks being frozen | |
1121 | * or not, as reported by the notification, remains unchanged *throughout the | |
1122 | * duration* of the execution of the callbacks. | |
1123 | * Hence we need to prevent the freezer from racing with regular CPU hotplug. | |
1124 | * | |
1125 | * This synchronization is implemented by mutually excluding regular CPU | |
1126 | * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/ | |
1127 | * Hibernate notifications. | |
1128 | */ | |
1129 | static int | |
1130 | cpu_hotplug_pm_callback(struct notifier_block *nb, | |
1131 | unsigned long action, void *ptr) | |
1132 | { | |
1133 | switch (action) { | |
1134 | ||
1135 | case PM_SUSPEND_PREPARE: | |
1136 | case PM_HIBERNATION_PREPARE: | |
1137 | cpu_hotplug_disable(); | |
1138 | break; | |
1139 | ||
1140 | case PM_POST_SUSPEND: | |
1141 | case PM_POST_HIBERNATION: | |
1142 | cpu_hotplug_enable(); | |
1143 | break; | |
1144 | ||
1145 | default: | |
1146 | return NOTIFY_DONE; | |
1147 | } | |
1148 | ||
1149 | return NOTIFY_OK; | |
1150 | } | |
1151 | ||
1152 | ||
1153 | static int __init cpu_hotplug_pm_sync_init(void) | |
1154 | { | |
1155 | /* | |
1156 | * cpu_hotplug_pm_callback has higher priority than x86 | |
1157 | * bsp_pm_callback which depends on cpu_hotplug_pm_callback | |
1158 | * to disable cpu hotplug to avoid cpu hotplug race. | |
1159 | */ | |
1160 | pm_notifier(cpu_hotplug_pm_callback, 0); | |
1161 | return 0; | |
1162 | } | |
1163 | core_initcall(cpu_hotplug_pm_sync_init); | |
1164 | ||
1165 | #endif /* CONFIG_PM_SLEEP_SMP */ | |
1166 | ||
1167 | #endif /* CONFIG_SMP */ | |
1168 | ||
1169 | /* Boot processor state steps */ | |
1170 | static struct cpuhp_step cpuhp_bp_states[] = { | |
1171 | [CPUHP_OFFLINE] = { | |
1172 | .name = "offline", | |
1173 | .startup = NULL, | |
1174 | .teardown = NULL, | |
1175 | }, | |
1176 | #ifdef CONFIG_SMP | |
1177 | [CPUHP_CREATE_THREADS]= { | |
1178 | .name = "threads:create", | |
1179 | .startup = smpboot_create_threads, | |
1180 | .teardown = NULL, | |
1181 | .cant_stop = true, | |
1182 | }, | |
1183 | /* | |
1184 | * Preparatory and dead notifiers. Will be replaced once the notifiers | |
1185 | * are converted to states. | |
1186 | */ | |
1187 | [CPUHP_NOTIFY_PREPARE] = { | |
1188 | .name = "notify:prepare", | |
1189 | .startup = notify_prepare, | |
1190 | .teardown = notify_dead, | |
1191 | .skip_onerr = true, | |
1192 | .cant_stop = true, | |
1193 | }, | |
1194 | /* Kicks the plugged cpu into life */ | |
1195 | [CPUHP_BRINGUP_CPU] = { | |
1196 | .name = "cpu:bringup", | |
1197 | .startup = bringup_cpu, | |
1198 | .teardown = NULL, | |
1199 | .cant_stop = true, | |
1200 | }, | |
1201 | /* | |
1202 | * Handled on controll processor until the plugged processor manages | |
1203 | * this itself. | |
1204 | */ | |
1205 | [CPUHP_TEARDOWN_CPU] = { | |
1206 | .name = "cpu:teardown", | |
1207 | .startup = NULL, | |
1208 | .teardown = takedown_cpu, | |
1209 | .cant_stop = true, | |
1210 | }, | |
1211 | #else | |
1212 | [CPUHP_BRINGUP_CPU] = { }, | |
1213 | #endif | |
1214 | }; | |
1215 | ||
1216 | /* Application processor state steps */ | |
1217 | static struct cpuhp_step cpuhp_ap_states[] = { | |
1218 | #ifdef CONFIG_SMP | |
1219 | /* Final state before CPU kills itself */ | |
1220 | [CPUHP_AP_IDLE_DEAD] = { | |
1221 | .name = "idle:dead", | |
1222 | }, | |
1223 | /* | |
1224 | * Last state before CPU enters the idle loop to die. Transient state | |
1225 | * for synchronization. | |
1226 | */ | |
1227 | [CPUHP_AP_OFFLINE] = { | |
1228 | .name = "ap:offline", | |
1229 | .cant_stop = true, | |
1230 | }, | |
1231 | /* First state is scheduler control. Interrupts are disabled */ | |
1232 | [CPUHP_AP_SCHED_STARTING] = { | |
1233 | .name = "sched:starting", | |
1234 | .startup = sched_cpu_starting, | |
1235 | .teardown = sched_cpu_dying, | |
1236 | }, | |
1237 | /* | |
1238 | * Low level startup/teardown notifiers. Run with interrupts | |
1239 | * disabled. Will be removed once the notifiers are converted to | |
1240 | * states. | |
1241 | */ | |
1242 | [CPUHP_AP_NOTIFY_STARTING] = { | |
1243 | .name = "notify:starting", | |
1244 | .startup = notify_starting, | |
1245 | .teardown = notify_dying, | |
1246 | .skip_onerr = true, | |
1247 | .cant_stop = true, | |
1248 | }, | |
1249 | /* Entry state on starting. Interrupts enabled from here on. Transient | |
1250 | * state for synchronsization */ | |
1251 | [CPUHP_AP_ONLINE] = { | |
1252 | .name = "ap:online", | |
1253 | }, | |
1254 | /* Handle smpboot threads park/unpark */ | |
1255 | [CPUHP_AP_SMPBOOT_THREADS] = { | |
1256 | .name = "smpboot:threads", | |
1257 | .startup = smpboot_unpark_threads, | |
1258 | .teardown = NULL, | |
1259 | }, | |
1260 | /* | |
1261 | * Online/down_prepare notifiers. Will be removed once the notifiers | |
1262 | * are converted to states. | |
1263 | */ | |
1264 | [CPUHP_AP_NOTIFY_ONLINE] = { | |
1265 | .name = "notify:online", | |
1266 | .startup = notify_online, | |
1267 | .teardown = notify_down_prepare, | |
1268 | .skip_onerr = true, | |
1269 | }, | |
1270 | #endif | |
1271 | /* | |
1272 | * The dynamically registered state space is here | |
1273 | */ | |
1274 | ||
1275 | #ifdef CONFIG_SMP | |
1276 | /* Last state is scheduler control setting the cpu active */ | |
1277 | [CPUHP_AP_ACTIVE] = { | |
1278 | .name = "sched:active", | |
1279 | .startup = sched_cpu_activate, | |
1280 | .teardown = sched_cpu_deactivate, | |
1281 | }, | |
1282 | #endif | |
1283 | ||
1284 | /* CPU is fully up and running. */ | |
1285 | [CPUHP_ONLINE] = { | |
1286 | .name = "online", | |
1287 | .startup = NULL, | |
1288 | .teardown = NULL, | |
1289 | }, | |
1290 | }; | |
1291 | ||
1292 | /* Sanity check for callbacks */ | |
1293 | static int cpuhp_cb_check(enum cpuhp_state state) | |
1294 | { | |
1295 | if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE) | |
1296 | return -EINVAL; | |
1297 | return 0; | |
1298 | } | |
1299 | ||
1300 | static bool cpuhp_is_ap_state(enum cpuhp_state state) | |
1301 | { | |
1302 | /* | |
1303 | * The extra check for CPUHP_TEARDOWN_CPU is only for documentation | |
1304 | * purposes as that state is handled explicitely in cpu_down. | |
1305 | */ | |
1306 | return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU; | |
1307 | } | |
1308 | ||
1309 | static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state) | |
1310 | { | |
1311 | struct cpuhp_step *sp; | |
1312 | ||
1313 | sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states; | |
1314 | return sp + state; | |
1315 | } | |
1316 | ||
1317 | static void cpuhp_store_callbacks(enum cpuhp_state state, | |
1318 | const char *name, | |
1319 | int (*startup)(unsigned int cpu), | |
1320 | int (*teardown)(unsigned int cpu)) | |
1321 | { | |
1322 | /* (Un)Install the callbacks for further cpu hotplug operations */ | |
1323 | struct cpuhp_step *sp; | |
1324 | ||
1325 | mutex_lock(&cpuhp_state_mutex); | |
1326 | sp = cpuhp_get_step(state); | |
1327 | sp->startup = startup; | |
1328 | sp->teardown = teardown; | |
1329 | sp->name = name; | |
1330 | mutex_unlock(&cpuhp_state_mutex); | |
1331 | } | |
1332 | ||
1333 | static void *cpuhp_get_teardown_cb(enum cpuhp_state state) | |
1334 | { | |
1335 | return cpuhp_get_step(state)->teardown; | |
1336 | } | |
1337 | ||
1338 | /* | |
1339 | * Call the startup/teardown function for a step either on the AP or | |
1340 | * on the current CPU. | |
1341 | */ | |
1342 | static int cpuhp_issue_call(int cpu, enum cpuhp_state state, | |
1343 | int (*cb)(unsigned int), bool bringup) | |
1344 | { | |
1345 | int ret; | |
1346 | ||
1347 | if (!cb) | |
1348 | return 0; | |
1349 | /* | |
1350 | * The non AP bound callbacks can fail on bringup. On teardown | |
1351 | * e.g. module removal we crash for now. | |
1352 | */ | |
1353 | #ifdef CONFIG_SMP | |
1354 | if (cpuhp_is_ap_state(state)) | |
1355 | ret = cpuhp_invoke_ap_callback(cpu, state, cb); | |
1356 | else | |
1357 | ret = cpuhp_invoke_callback(cpu, state, cb); | |
1358 | #else | |
1359 | ret = cpuhp_invoke_callback(cpu, state, cb); | |
1360 | #endif | |
1361 | BUG_ON(ret && !bringup); | |
1362 | return ret; | |
1363 | } | |
1364 | ||
1365 | /* | |
1366 | * Called from __cpuhp_setup_state on a recoverable failure. | |
1367 | * | |
1368 | * Note: The teardown callbacks for rollback are not allowed to fail! | |
1369 | */ | |
1370 | static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state, | |
1371 | int (*teardown)(unsigned int cpu)) | |
1372 | { | |
1373 | int cpu; | |
1374 | ||
1375 | if (!teardown) | |
1376 | return; | |
1377 | ||
1378 | /* Roll back the already executed steps on the other cpus */ | |
1379 | for_each_present_cpu(cpu) { | |
1380 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
1381 | int cpustate = st->state; | |
1382 | ||
1383 | if (cpu >= failedcpu) | |
1384 | break; | |
1385 | ||
1386 | /* Did we invoke the startup call on that cpu ? */ | |
1387 | if (cpustate >= state) | |
1388 | cpuhp_issue_call(cpu, state, teardown, false); | |
1389 | } | |
1390 | } | |
1391 | ||
1392 | /* | |
1393 | * Returns a free for dynamic slot assignment of the Online state. The states | |
1394 | * are protected by the cpuhp_slot_states mutex and an empty slot is identified | |
1395 | * by having no name assigned. | |
1396 | */ | |
1397 | static int cpuhp_reserve_state(enum cpuhp_state state) | |
1398 | { | |
1399 | enum cpuhp_state i; | |
1400 | ||
1401 | mutex_lock(&cpuhp_state_mutex); | |
1402 | for (i = CPUHP_AP_ONLINE_DYN; i <= CPUHP_AP_ONLINE_DYN_END; i++) { | |
1403 | if (cpuhp_ap_states[i].name) | |
1404 | continue; | |
1405 | ||
1406 | cpuhp_ap_states[i].name = "Reserved"; | |
1407 | mutex_unlock(&cpuhp_state_mutex); | |
1408 | return i; | |
1409 | } | |
1410 | mutex_unlock(&cpuhp_state_mutex); | |
1411 | WARN(1, "No more dynamic states available for CPU hotplug\n"); | |
1412 | return -ENOSPC; | |
1413 | } | |
1414 | ||
1415 | /** | |
1416 | * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state | |
1417 | * @state: The state to setup | |
1418 | * @invoke: If true, the startup function is invoked for cpus where | |
1419 | * cpu state >= @state | |
1420 | * @startup: startup callback function | |
1421 | * @teardown: teardown callback function | |
1422 | * | |
1423 | * Returns 0 if successful, otherwise a proper error code | |
1424 | */ | |
1425 | int __cpuhp_setup_state(enum cpuhp_state state, | |
1426 | const char *name, bool invoke, | |
1427 | int (*startup)(unsigned int cpu), | |
1428 | int (*teardown)(unsigned int cpu)) | |
1429 | { | |
1430 | int cpu, ret = 0; | |
1431 | int dyn_state = 0; | |
1432 | ||
1433 | if (cpuhp_cb_check(state) || !name) | |
1434 | return -EINVAL; | |
1435 | ||
1436 | get_online_cpus(); | |
1437 | ||
1438 | /* currently assignments for the ONLINE state are possible */ | |
1439 | if (state == CPUHP_AP_ONLINE_DYN) { | |
1440 | dyn_state = 1; | |
1441 | ret = cpuhp_reserve_state(state); | |
1442 | if (ret < 0) | |
1443 | goto out; | |
1444 | state = ret; | |
1445 | } | |
1446 | ||
1447 | cpuhp_store_callbacks(state, name, startup, teardown); | |
1448 | ||
1449 | if (!invoke || !startup) | |
1450 | goto out; | |
1451 | ||
1452 | /* | |
1453 | * Try to call the startup callback for each present cpu | |
1454 | * depending on the hotplug state of the cpu. | |
1455 | */ | |
1456 | for_each_present_cpu(cpu) { | |
1457 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
1458 | int cpustate = st->state; | |
1459 | ||
1460 | if (cpustate < state) | |
1461 | continue; | |
1462 | ||
1463 | ret = cpuhp_issue_call(cpu, state, startup, true); | |
1464 | if (ret) { | |
1465 | cpuhp_rollback_install(cpu, state, teardown); | |
1466 | cpuhp_store_callbacks(state, NULL, NULL, NULL); | |
1467 | goto out; | |
1468 | } | |
1469 | } | |
1470 | out: | |
1471 | put_online_cpus(); | |
1472 | if (!ret && dyn_state) | |
1473 | return state; | |
1474 | return ret; | |
1475 | } | |
1476 | EXPORT_SYMBOL(__cpuhp_setup_state); | |
1477 | ||
1478 | /** | |
1479 | * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state | |
1480 | * @state: The state to remove | |
1481 | * @invoke: If true, the teardown function is invoked for cpus where | |
1482 | * cpu state >= @state | |
1483 | * | |
1484 | * The teardown callback is currently not allowed to fail. Think | |
1485 | * about module removal! | |
1486 | */ | |
1487 | void __cpuhp_remove_state(enum cpuhp_state state, bool invoke) | |
1488 | { | |
1489 | int (*teardown)(unsigned int cpu) = cpuhp_get_teardown_cb(state); | |
1490 | int cpu; | |
1491 | ||
1492 | BUG_ON(cpuhp_cb_check(state)); | |
1493 | ||
1494 | get_online_cpus(); | |
1495 | ||
1496 | if (!invoke || !teardown) | |
1497 | goto remove; | |
1498 | ||
1499 | /* | |
1500 | * Call the teardown callback for each present cpu depending | |
1501 | * on the hotplug state of the cpu. This function is not | |
1502 | * allowed to fail currently! | |
1503 | */ | |
1504 | for_each_present_cpu(cpu) { | |
1505 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); | |
1506 | int cpustate = st->state; | |
1507 | ||
1508 | if (cpustate >= state) | |
1509 | cpuhp_issue_call(cpu, state, teardown, false); | |
1510 | } | |
1511 | remove: | |
1512 | cpuhp_store_callbacks(state, NULL, NULL, NULL); | |
1513 | put_online_cpus(); | |
1514 | } | |
1515 | EXPORT_SYMBOL(__cpuhp_remove_state); | |
1516 | ||
1517 | #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU) | |
1518 | static ssize_t show_cpuhp_state(struct device *dev, | |
1519 | struct device_attribute *attr, char *buf) | |
1520 | { | |
1521 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); | |
1522 | ||
1523 | return sprintf(buf, "%d\n", st->state); | |
1524 | } | |
1525 | static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL); | |
1526 | ||
1527 | static ssize_t write_cpuhp_target(struct device *dev, | |
1528 | struct device_attribute *attr, | |
1529 | const char *buf, size_t count) | |
1530 | { | |
1531 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); | |
1532 | struct cpuhp_step *sp; | |
1533 | int target, ret; | |
1534 | ||
1535 | ret = kstrtoint(buf, 10, &target); | |
1536 | if (ret) | |
1537 | return ret; | |
1538 | ||
1539 | #ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL | |
1540 | if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE) | |
1541 | return -EINVAL; | |
1542 | #else | |
1543 | if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE) | |
1544 | return -EINVAL; | |
1545 | #endif | |
1546 | ||
1547 | ret = lock_device_hotplug_sysfs(); | |
1548 | if (ret) | |
1549 | return ret; | |
1550 | ||
1551 | mutex_lock(&cpuhp_state_mutex); | |
1552 | sp = cpuhp_get_step(target); | |
1553 | ret = !sp->name || sp->cant_stop ? -EINVAL : 0; | |
1554 | mutex_unlock(&cpuhp_state_mutex); | |
1555 | if (ret) | |
1556 | return ret; | |
1557 | ||
1558 | if (st->state < target) | |
1559 | ret = do_cpu_up(dev->id, target); | |
1560 | else | |
1561 | ret = do_cpu_down(dev->id, target); | |
1562 | ||
1563 | unlock_device_hotplug(); | |
1564 | return ret ? ret : count; | |
1565 | } | |
1566 | ||
1567 | static ssize_t show_cpuhp_target(struct device *dev, | |
1568 | struct device_attribute *attr, char *buf) | |
1569 | { | |
1570 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); | |
1571 | ||
1572 | return sprintf(buf, "%d\n", st->target); | |
1573 | } | |
1574 | static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target); | |
1575 | ||
1576 | static struct attribute *cpuhp_cpu_attrs[] = { | |
1577 | &dev_attr_state.attr, | |
1578 | &dev_attr_target.attr, | |
1579 | NULL | |
1580 | }; | |
1581 | ||
1582 | static struct attribute_group cpuhp_cpu_attr_group = { | |
1583 | .attrs = cpuhp_cpu_attrs, | |
1584 | .name = "hotplug", | |
1585 | NULL | |
1586 | }; | |
1587 | ||
1588 | static ssize_t show_cpuhp_states(struct device *dev, | |
1589 | struct device_attribute *attr, char *buf) | |
1590 | { | |
1591 | ssize_t cur, res = 0; | |
1592 | int i; | |
1593 | ||
1594 | mutex_lock(&cpuhp_state_mutex); | |
1595 | for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) { | |
1596 | struct cpuhp_step *sp = cpuhp_get_step(i); | |
1597 | ||
1598 | if (sp->name) { | |
1599 | cur = sprintf(buf, "%3d: %s\n", i, sp->name); | |
1600 | buf += cur; | |
1601 | res += cur; | |
1602 | } | |
1603 | } | |
1604 | mutex_unlock(&cpuhp_state_mutex); | |
1605 | return res; | |
1606 | } | |
1607 | static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL); | |
1608 | ||
1609 | static struct attribute *cpuhp_cpu_root_attrs[] = { | |
1610 | &dev_attr_states.attr, | |
1611 | NULL | |
1612 | }; | |
1613 | ||
1614 | static struct attribute_group cpuhp_cpu_root_attr_group = { | |
1615 | .attrs = cpuhp_cpu_root_attrs, | |
1616 | .name = "hotplug", | |
1617 | NULL | |
1618 | }; | |
1619 | ||
1620 | static int __init cpuhp_sysfs_init(void) | |
1621 | { | |
1622 | int cpu, ret; | |
1623 | ||
1624 | ret = sysfs_create_group(&cpu_subsys.dev_root->kobj, | |
1625 | &cpuhp_cpu_root_attr_group); | |
1626 | if (ret) | |
1627 | return ret; | |
1628 | ||
1629 | for_each_possible_cpu(cpu) { | |
1630 | struct device *dev = get_cpu_device(cpu); | |
1631 | ||
1632 | if (!dev) | |
1633 | continue; | |
1634 | ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group); | |
1635 | if (ret) | |
1636 | return ret; | |
1637 | } | |
1638 | return 0; | |
1639 | } | |
1640 | device_initcall(cpuhp_sysfs_init); | |
1641 | #endif | |
1642 | ||
1643 | /* | |
1644 | * cpu_bit_bitmap[] is a special, "compressed" data structure that | |
1645 | * represents all NR_CPUS bits binary values of 1<<nr. | |
1646 | * | |
1647 | * It is used by cpumask_of() to get a constant address to a CPU | |
1648 | * mask value that has a single bit set only. | |
1649 | */ | |
1650 | ||
1651 | /* cpu_bit_bitmap[0] is empty - so we can back into it */ | |
1652 | #define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x)) | |
1653 | #define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1) | |
1654 | #define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2) | |
1655 | #define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4) | |
1656 | ||
1657 | const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = { | |
1658 | ||
1659 | MASK_DECLARE_8(0), MASK_DECLARE_8(8), | |
1660 | MASK_DECLARE_8(16), MASK_DECLARE_8(24), | |
1661 | #if BITS_PER_LONG > 32 | |
1662 | MASK_DECLARE_8(32), MASK_DECLARE_8(40), | |
1663 | MASK_DECLARE_8(48), MASK_DECLARE_8(56), | |
1664 | #endif | |
1665 | }; | |
1666 | EXPORT_SYMBOL_GPL(cpu_bit_bitmap); | |
1667 | ||
1668 | const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL; | |
1669 | EXPORT_SYMBOL(cpu_all_bits); | |
1670 | ||
1671 | #ifdef CONFIG_INIT_ALL_POSSIBLE | |
1672 | struct cpumask __cpu_possible_mask __read_mostly | |
1673 | = {CPU_BITS_ALL}; | |
1674 | #else | |
1675 | struct cpumask __cpu_possible_mask __read_mostly; | |
1676 | #endif | |
1677 | EXPORT_SYMBOL(__cpu_possible_mask); | |
1678 | ||
1679 | struct cpumask __cpu_online_mask __read_mostly; | |
1680 | EXPORT_SYMBOL(__cpu_online_mask); | |
1681 | ||
1682 | struct cpumask __cpu_present_mask __read_mostly; | |
1683 | EXPORT_SYMBOL(__cpu_present_mask); | |
1684 | ||
1685 | struct cpumask __cpu_active_mask __read_mostly; | |
1686 | EXPORT_SYMBOL(__cpu_active_mask); | |
1687 | ||
1688 | void init_cpu_present(const struct cpumask *src) | |
1689 | { | |
1690 | cpumask_copy(&__cpu_present_mask, src); | |
1691 | } | |
1692 | ||
1693 | void init_cpu_possible(const struct cpumask *src) | |
1694 | { | |
1695 | cpumask_copy(&__cpu_possible_mask, src); | |
1696 | } | |
1697 | ||
1698 | void init_cpu_online(const struct cpumask *src) | |
1699 | { | |
1700 | cpumask_copy(&__cpu_online_mask, src); | |
1701 | } | |
1702 | ||
1703 | /* | |
1704 | * Activate the first processor. | |
1705 | */ | |
1706 | void __init boot_cpu_init(void) | |
1707 | { | |
1708 | int cpu = smp_processor_id(); | |
1709 | ||
1710 | /* Mark the boot cpu "present", "online" etc for SMP and UP case */ | |
1711 | set_cpu_online(cpu, true); | |
1712 | set_cpu_active(cpu, true); | |
1713 | set_cpu_present(cpu, true); | |
1714 | set_cpu_possible(cpu, true); | |
1715 | } | |
1716 | ||
1717 | /* | |
1718 | * Must be called _AFTER_ setting up the per_cpu areas | |
1719 | */ | |
1720 | void __init boot_cpu_state_init(void) | |
1721 | { | |
1722 | per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE; | |
1723 | } |