projects/linux·blob v4.7 · refs

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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 */
45struct 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
59static 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 */
70struct 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
78static DEFINE_MUTEX(cpuhp_state_mutex);
79static struct cpuhp_step cpuhp_bp_states[];
80static 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 */
90static 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 */
106static DEFINE_MUTEX(cpu_add_remove_lock);
107bool cpuhp_tasks_frozen;
108EXPORT_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 */
117void cpu_maps_update_begin(void)
118{
119 mutex_lock(&cpu_add_remove_lock);
120}
121EXPORT_SYMBOL(cpu_notifier_register_begin);
122
123void cpu_maps_update_done(void)
124{
125 mutex_unlock(&cpu_add_remove_lock);
126}
127EXPORT_SYMBOL(cpu_notifier_register_done);
128
129static 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 */
134static int cpu_hotplug_disabled;
135
136#ifdef CONFIG_HOTPLUG_CPU
137
138static 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
170void 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}
180EXPORT_SYMBOL_GPL(get_online_cpus);
181
182void 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}
199EXPORT_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 */
223void 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
241void 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 */
255void cpu_hotplug_disable(void)
256{
257 cpu_maps_update_begin();
258 cpu_hotplug_disabled++;
259 cpu_maps_update_done();
260}
261EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
262
263void cpu_hotplug_enable(void)
264{
265 cpu_maps_update_begin();
266 WARN_ON(--cpu_hotplug_disabled < 0);
267 cpu_maps_update_done();
268}
269EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
270#endif /* CONFIG_HOTPLUG_CPU */
271
272/* Need to know about CPUs going up/down? */
273int 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
282int __register_cpu_notifier(struct notifier_block *nb)
283{
284 return raw_notifier_chain_register(&cpu_chain, nb);
285}
286
287static 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
301static int cpu_notify(unsigned long val, unsigned int cpu)
302{
303 return __cpu_notify(val, cpu, -1, NULL);
304}
305
306static 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 */
312static 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
327static int notify_online(unsigned int cpu)
328{
329 cpu_notify(CPU_ONLINE, cpu);
330 return 0;
331}
332
333static int notify_starting(unsigned int cpu)
334{
335 cpu_notify(CPU_STARTING, cpu);
336 return 0;
337}
338
339static 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
347static 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 */
366static 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
377static 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
396static 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
407static 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 */
431static 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
438static 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 */
446static 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 */
454static 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 */
463static 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 */
512static 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 st->cb_state = state;
521 st->cb = cb;
522 /*
523 * Make sure the above stores are visible before should_run becomes
524 * true. Paired with the mb() above in cpuhp_thread_fun()
525 */
526 smp_mb();
527 st->should_run = true;
528 wake_up_process(st->thread);
529 wait_for_completion(&st->done);
530 return st->result;
531}
532
533/* Regular hotplug invocation of the AP hotplug thread */
534static void __cpuhp_kick_ap_work(struct cpuhp_cpu_state *st)
535{
536 st->result = 0;
537 st->cb = NULL;
538 /*
539 * Make sure the above stores are visible before should_run becomes
540 * true. Paired with the mb() above in cpuhp_thread_fun()
541 */
542 smp_mb();
543 st->should_run = true;
544 wake_up_process(st->thread);
545}
546
547static int cpuhp_kick_ap_work(unsigned int cpu)
548{
549 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
550 enum cpuhp_state state = st->state;
551
552 trace_cpuhp_enter(cpu, st->target, state, cpuhp_kick_ap_work);
553 __cpuhp_kick_ap_work(st);
554 wait_for_completion(&st->done);
555 trace_cpuhp_exit(cpu, st->state, state, st->result);
556 return st->result;
557}
558
559static struct smp_hotplug_thread cpuhp_threads = {
560 .store = &cpuhp_state.thread,
561 .create = &cpuhp_create,
562 .thread_should_run = cpuhp_should_run,
563 .thread_fn = cpuhp_thread_fun,
564 .thread_comm = "cpuhp/%u",
565 .selfparking = true,
566};
567
568void __init cpuhp_threads_init(void)
569{
570 BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads));
571 kthread_unpark(this_cpu_read(cpuhp_state.thread));
572}
573
574#ifdef CONFIG_HOTPLUG_CPU
575EXPORT_SYMBOL(register_cpu_notifier);
576EXPORT_SYMBOL(__register_cpu_notifier);
577void unregister_cpu_notifier(struct notifier_block *nb)
578{
579 cpu_maps_update_begin();
580 raw_notifier_chain_unregister(&cpu_chain, nb);
581 cpu_maps_update_done();
582}
583EXPORT_SYMBOL(unregister_cpu_notifier);
584
585void __unregister_cpu_notifier(struct notifier_block *nb)
586{
587 raw_notifier_chain_unregister(&cpu_chain, nb);
588}
589EXPORT_SYMBOL(__unregister_cpu_notifier);
590
591/**
592 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
593 * @cpu: a CPU id
594 *
595 * This function walks all processes, finds a valid mm struct for each one and
596 * then clears a corresponding bit in mm's cpumask. While this all sounds
597 * trivial, there are various non-obvious corner cases, which this function
598 * tries to solve in a safe manner.
599 *
600 * Also note that the function uses a somewhat relaxed locking scheme, so it may
601 * be called only for an already offlined CPU.
602 */
603void clear_tasks_mm_cpumask(int cpu)
604{
605 struct task_struct *p;
606
607 /*
608 * This function is called after the cpu is taken down and marked
609 * offline, so its not like new tasks will ever get this cpu set in
610 * their mm mask. -- Peter Zijlstra
611 * Thus, we may use rcu_read_lock() here, instead of grabbing
612 * full-fledged tasklist_lock.
613 */
614 WARN_ON(cpu_online(cpu));
615 rcu_read_lock();
616 for_each_process(p) {
617 struct task_struct *t;
618
619 /*
620 * Main thread might exit, but other threads may still have
621 * a valid mm. Find one.
622 */
623 t = find_lock_task_mm(p);
624 if (!t)
625 continue;
626 cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
627 task_unlock(t);
628 }
629 rcu_read_unlock();
630}
631
632static inline void check_for_tasks(int dead_cpu)
633{
634 struct task_struct *g, *p;
635
636 read_lock(&tasklist_lock);
637 for_each_process_thread(g, p) {
638 if (!p->on_rq)
639 continue;
640 /*
641 * We do the check with unlocked task_rq(p)->lock.
642 * Order the reading to do not warn about a task,
643 * which was running on this cpu in the past, and
644 * it's just been woken on another cpu.
645 */
646 rmb();
647 if (task_cpu(p) != dead_cpu)
648 continue;
649
650 pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
651 p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
652 }
653 read_unlock(&tasklist_lock);
654}
655
656static int notify_down_prepare(unsigned int cpu)
657{
658 int err, nr_calls = 0;
659
660 err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls);
661 if (err) {
662 nr_calls--;
663 __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL);
664 pr_warn("%s: attempt to take down CPU %u failed\n",
665 __func__, cpu);
666 }
667 return err;
668}
669
670static int notify_dying(unsigned int cpu)
671{
672 cpu_notify(CPU_DYING, cpu);
673 return 0;
674}
675
676/* Take this CPU down. */
677static int take_cpu_down(void *_param)
678{
679 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
680 enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE);
681 int err, cpu = smp_processor_id();
682
683 /* Ensure this CPU doesn't handle any more interrupts. */
684 err = __cpu_disable();
685 if (err < 0)
686 return err;
687
688 /* Invoke the former CPU_DYING callbacks */
689 for (; st->state > target; st->state--) {
690 struct cpuhp_step *step = cpuhp_ap_states + st->state;
691
692 cpuhp_invoke_callback(cpu, st->state, step->teardown);
693 }
694 /* Give up timekeeping duties */
695 tick_handover_do_timer();
696 /* Park the stopper thread */
697 stop_machine_park(cpu);
698 return 0;
699}
700
701static int takedown_cpu(unsigned int cpu)
702{
703 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
704 int err;
705
706 /* Park the smpboot threads */
707 kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread);
708 smpboot_park_threads(cpu);
709
710 /*
711 * Prevent irq alloc/free while the dying cpu reorganizes the
712 * interrupt affinities.
713 */
714 irq_lock_sparse();
715
716 /*
717 * So now all preempt/rcu users must observe !cpu_active().
718 */
719 err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu));
720 if (err) {
721 /* CPU refused to die */
722 irq_unlock_sparse();
723 /* Unpark the hotplug thread so we can rollback there */
724 kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread);
725 return err;
726 }
727 BUG_ON(cpu_online(cpu));
728
729 /*
730 * The migration_call() CPU_DYING callback will have removed all
731 * runnable tasks from the cpu, there's only the idle task left now
732 * that the migration thread is done doing the stop_machine thing.
733 *
734 * Wait for the stop thread to go away.
735 */
736 wait_for_completion(&st->done);
737 BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
738
739 /* Interrupts are moved away from the dying cpu, reenable alloc/free */
740 irq_unlock_sparse();
741
742 hotplug_cpu__broadcast_tick_pull(cpu);
743 /* This actually kills the CPU. */
744 __cpu_die(cpu);
745
746 tick_cleanup_dead_cpu(cpu);
747 return 0;
748}
749
750static int notify_dead(unsigned int cpu)
751{
752 cpu_notify_nofail(CPU_DEAD, cpu);
753 check_for_tasks(cpu);
754 return 0;
755}
756
757static void cpuhp_complete_idle_dead(void *arg)
758{
759 struct cpuhp_cpu_state *st = arg;
760
761 complete(&st->done);
762}
763
764void cpuhp_report_idle_dead(void)
765{
766 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
767
768 BUG_ON(st->state != CPUHP_AP_OFFLINE);
769 rcu_report_dead(smp_processor_id());
770 st->state = CPUHP_AP_IDLE_DEAD;
771 /*
772 * We cannot call complete after rcu_report_dead() so we delegate it
773 * to an online cpu.
774 */
775 smp_call_function_single(cpumask_first(cpu_online_mask),
776 cpuhp_complete_idle_dead, st, 0);
777}
778
779#else
780#define notify_down_prepare NULL
781#define takedown_cpu NULL
782#define notify_dead NULL
783#define notify_dying NULL
784#endif
785
786#ifdef CONFIG_HOTPLUG_CPU
787
788/* Requires cpu_add_remove_lock to be held */
789static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
790 enum cpuhp_state target)
791{
792 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
793 int prev_state, ret = 0;
794 bool hasdied = false;
795
796 if (num_online_cpus() == 1)
797 return -EBUSY;
798
799 if (!cpu_present(cpu))
800 return -EINVAL;
801
802 cpu_hotplug_begin();
803
804 cpuhp_tasks_frozen = tasks_frozen;
805
806 prev_state = st->state;
807 st->target = target;
808 /*
809 * If the current CPU state is in the range of the AP hotplug thread,
810 * then we need to kick the thread.
811 */
812 if (st->state > CPUHP_TEARDOWN_CPU) {
813 ret = cpuhp_kick_ap_work(cpu);
814 /*
815 * The AP side has done the error rollback already. Just
816 * return the error code..
817 */
818 if (ret)
819 goto out;
820
821 /*
822 * We might have stopped still in the range of the AP hotplug
823 * thread. Nothing to do anymore.
824 */
825 if (st->state > CPUHP_TEARDOWN_CPU)
826 goto out;
827 }
828 /*
829 * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need
830 * to do the further cleanups.
831 */
832 ret = cpuhp_down_callbacks(cpu, st, cpuhp_bp_states, target);
833 if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) {
834 st->target = prev_state;
835 st->rollback = true;
836 cpuhp_kick_ap_work(cpu);
837 }
838
839 hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE;
840out:
841 cpu_hotplug_done();
842 /* This post dead nonsense must die */
843 if (!ret && hasdied)
844 cpu_notify_nofail(CPU_POST_DEAD, cpu);
845 return ret;
846}
847
848static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
849{
850 int err;
851
852 cpu_maps_update_begin();
853
854 if (cpu_hotplug_disabled) {
855 err = -EBUSY;
856 goto out;
857 }
858
859 err = _cpu_down(cpu, 0, target);
860
861out:
862 cpu_maps_update_done();
863 return err;
864}
865int cpu_down(unsigned int cpu)
866{
867 return do_cpu_down(cpu, CPUHP_OFFLINE);
868}
869EXPORT_SYMBOL(cpu_down);
870#endif /*CONFIG_HOTPLUG_CPU*/
871
872/**
873 * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
874 * @cpu: cpu that just started
875 *
876 * This function calls the cpu_chain notifiers with CPU_STARTING.
877 * It must be called by the arch code on the new cpu, before the new cpu
878 * enables interrupts and before the "boot" cpu returns from __cpu_up().
879 */
880void notify_cpu_starting(unsigned int cpu)
881{
882 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
883 enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
884
885 while (st->state < target) {
886 struct cpuhp_step *step;
887
888 st->state++;
889 step = cpuhp_ap_states + st->state;
890 cpuhp_invoke_callback(cpu, st->state, step->startup);
891 }
892}
893
894/*
895 * Called from the idle task. We need to set active here, so we can kick off
896 * the stopper thread and unpark the smpboot threads. If the target state is
897 * beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the
898 * cpu further.
899 */
900void cpuhp_online_idle(enum cpuhp_state state)
901{
902 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
903 unsigned int cpu = smp_processor_id();
904
905 /* Happens for the boot cpu */
906 if (state != CPUHP_AP_ONLINE_IDLE)
907 return;
908
909 st->state = CPUHP_AP_ONLINE_IDLE;
910
911 /* Unpark the stopper thread and the hotplug thread of this cpu */
912 stop_machine_unpark(cpu);
913 kthread_unpark(st->thread);
914
915 /* Should we go further up ? */
916 if (st->target > CPUHP_AP_ONLINE_IDLE)
917 __cpuhp_kick_ap_work(st);
918 else
919 complete(&st->done);
920}
921
922/* Requires cpu_add_remove_lock to be held */
923static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
924{
925 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
926 struct task_struct *idle;
927 int ret = 0;
928
929 cpu_hotplug_begin();
930
931 if (!cpu_present(cpu)) {
932 ret = -EINVAL;
933 goto out;
934 }
935
936 /*
937 * The caller of do_cpu_up might have raced with another
938 * caller. Ignore it for now.
939 */
940 if (st->state >= target)
941 goto out;
942
943 if (st->state == CPUHP_OFFLINE) {
944 /* Let it fail before we try to bring the cpu up */
945 idle = idle_thread_get(cpu);
946 if (IS_ERR(idle)) {
947 ret = PTR_ERR(idle);
948 goto out;
949 }
950 }
951
952 cpuhp_tasks_frozen = tasks_frozen;
953
954 st->target = target;
955 /*
956 * If the current CPU state is in the range of the AP hotplug thread,
957 * then we need to kick the thread once more.
958 */
959 if (st->state > CPUHP_BRINGUP_CPU) {
960 ret = cpuhp_kick_ap_work(cpu);
961 /*
962 * The AP side has done the error rollback already. Just
963 * return the error code..
964 */
965 if (ret)
966 goto out;
967 }
968
969 /*
970 * Try to reach the target state. We max out on the BP at
971 * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
972 * responsible for bringing it up to the target state.
973 */
974 target = min((int)target, CPUHP_BRINGUP_CPU);
975 ret = cpuhp_up_callbacks(cpu, st, cpuhp_bp_states, target);
976out:
977 cpu_hotplug_done();
978 return ret;
979}
980
981static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
982{
983 int err = 0;
984
985 if (!cpu_possible(cpu)) {
986 pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
987 cpu);
988#if defined(CONFIG_IA64)
989 pr_err("please check additional_cpus= boot parameter\n");
990#endif
991 return -EINVAL;
992 }
993
994 err = try_online_node(cpu_to_node(cpu));
995 if (err)
996 return err;
997
998 cpu_maps_update_begin();
999
1000 if (cpu_hotplug_disabled) {
1001 err = -EBUSY;
1002 goto out;
1003 }
1004
1005 err = _cpu_up(cpu, 0, target);
1006out:
1007 cpu_maps_update_done();
1008 return err;
1009}
1010
1011int cpu_up(unsigned int cpu)
1012{
1013 return do_cpu_up(cpu, CPUHP_ONLINE);
1014}
1015EXPORT_SYMBOL_GPL(cpu_up);
1016
1017#ifdef CONFIG_PM_SLEEP_SMP
1018static cpumask_var_t frozen_cpus;
1019
1020int disable_nonboot_cpus(void)
1021{
1022 int cpu, first_cpu, error = 0;
1023
1024 cpu_maps_update_begin();
1025 first_cpu = cpumask_first(cpu_online_mask);
1026 /*
1027 * We take down all of the non-boot CPUs in one shot to avoid races
1028 * with the userspace trying to use the CPU hotplug at the same time
1029 */
1030 cpumask_clear(frozen_cpus);
1031
1032 pr_info("Disabling non-boot CPUs ...\n");
1033 for_each_online_cpu(cpu) {
1034 if (cpu == first_cpu)
1035 continue;
1036 trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
1037 error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
1038 trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
1039 if (!error)
1040 cpumask_set_cpu(cpu, frozen_cpus);
1041 else {
1042 pr_err("Error taking CPU%d down: %d\n", cpu, error);
1043 break;
1044 }
1045 }
1046
1047 if (!error)
1048 BUG_ON(num_online_cpus() > 1);
1049 else
1050 pr_err("Non-boot CPUs are not disabled\n");
1051
1052 /*
1053 * Make sure the CPUs won't be enabled by someone else. We need to do
1054 * this even in case of failure as all disable_nonboot_cpus() users are
1055 * supposed to do enable_nonboot_cpus() on the failure path.
1056 */
1057 cpu_hotplug_disabled++;
1058
1059 cpu_maps_update_done();
1060 return error;
1061}
1062
1063void __weak arch_enable_nonboot_cpus_begin(void)
1064{
1065}
1066
1067void __weak arch_enable_nonboot_cpus_end(void)
1068{
1069}
1070
1071void enable_nonboot_cpus(void)
1072{
1073 int cpu, error;
1074
1075 /* Allow everyone to use the CPU hotplug again */
1076 cpu_maps_update_begin();
1077 WARN_ON(--cpu_hotplug_disabled < 0);
1078 if (cpumask_empty(frozen_cpus))
1079 goto out;
1080
1081 pr_info("Enabling non-boot CPUs ...\n");
1082
1083 arch_enable_nonboot_cpus_begin();
1084
1085 for_each_cpu(cpu, frozen_cpus) {
1086 trace_suspend_resume(TPS("CPU_ON"), cpu, true);
1087 error = _cpu_up(cpu, 1, CPUHP_ONLINE);
1088 trace_suspend_resume(TPS("CPU_ON"), cpu, false);
1089 if (!error) {
1090 pr_info("CPU%d is up\n", cpu);
1091 continue;
1092 }
1093 pr_warn("Error taking CPU%d up: %d\n", cpu, error);
1094 }
1095
1096 arch_enable_nonboot_cpus_end();
1097
1098 cpumask_clear(frozen_cpus);
1099out:
1100 cpu_maps_update_done();
1101}
1102
1103static int __init alloc_frozen_cpus(void)
1104{
1105 if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
1106 return -ENOMEM;
1107 return 0;
1108}
1109core_initcall(alloc_frozen_cpus);
1110
1111/*
1112 * When callbacks for CPU hotplug notifications are being executed, we must
1113 * ensure that the state of the system with respect to the tasks being frozen
1114 * or not, as reported by the notification, remains unchanged *throughout the
1115 * duration* of the execution of the callbacks.
1116 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
1117 *
1118 * This synchronization is implemented by mutually excluding regular CPU
1119 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
1120 * Hibernate notifications.
1121 */
1122static int
1123cpu_hotplug_pm_callback(struct notifier_block *nb,
1124 unsigned long action, void *ptr)
1125{
1126 switch (action) {
1127
1128 case PM_SUSPEND_PREPARE:
1129 case PM_HIBERNATION_PREPARE:
1130 cpu_hotplug_disable();
1131 break;
1132
1133 case PM_POST_SUSPEND:
1134 case PM_POST_HIBERNATION:
1135 cpu_hotplug_enable();
1136 break;
1137
1138 default:
1139 return NOTIFY_DONE;
1140 }
1141
1142 return NOTIFY_OK;
1143}
1144
1145
1146static int __init cpu_hotplug_pm_sync_init(void)
1147{
1148 /*
1149 * cpu_hotplug_pm_callback has higher priority than x86
1150 * bsp_pm_callback which depends on cpu_hotplug_pm_callback
1151 * to disable cpu hotplug to avoid cpu hotplug race.
1152 */
1153 pm_notifier(cpu_hotplug_pm_callback, 0);
1154 return 0;
1155}
1156core_initcall(cpu_hotplug_pm_sync_init);
1157
1158#endif /* CONFIG_PM_SLEEP_SMP */
1159
1160#endif /* CONFIG_SMP */
1161
1162/* Boot processor state steps */
1163static struct cpuhp_step cpuhp_bp_states[] = {
1164 [CPUHP_OFFLINE] = {
1165 .name = "offline",
1166 .startup = NULL,
1167 .teardown = NULL,
1168 },
1169#ifdef CONFIG_SMP
1170 [CPUHP_CREATE_THREADS]= {
1171 .name = "threads:create",
1172 .startup = smpboot_create_threads,
1173 .teardown = NULL,
1174 .cant_stop = true,
1175 },
1176 /*
1177 * Preparatory and dead notifiers. Will be replaced once the notifiers
1178 * are converted to states.
1179 */
1180 [CPUHP_NOTIFY_PREPARE] = {
1181 .name = "notify:prepare",
1182 .startup = notify_prepare,
1183 .teardown = notify_dead,
1184 .skip_onerr = true,
1185 .cant_stop = true,
1186 },
1187 /* Kicks the plugged cpu into life */
1188 [CPUHP_BRINGUP_CPU] = {
1189 .name = "cpu:bringup",
1190 .startup = bringup_cpu,
1191 .teardown = NULL,
1192 .cant_stop = true,
1193 },
1194 /*
1195 * Handled on controll processor until the plugged processor manages
1196 * this itself.
1197 */
1198 [CPUHP_TEARDOWN_CPU] = {
1199 .name = "cpu:teardown",
1200 .startup = NULL,
1201 .teardown = takedown_cpu,
1202 .cant_stop = true,
1203 },
1204#else
1205 [CPUHP_BRINGUP_CPU] = { },
1206#endif
1207};
1208
1209/* Application processor state steps */
1210static struct cpuhp_step cpuhp_ap_states[] = {
1211#ifdef CONFIG_SMP
1212 /* Final state before CPU kills itself */
1213 [CPUHP_AP_IDLE_DEAD] = {
1214 .name = "idle:dead",
1215 },
1216 /*
1217 * Last state before CPU enters the idle loop to die. Transient state
1218 * for synchronization.
1219 */
1220 [CPUHP_AP_OFFLINE] = {
1221 .name = "ap:offline",
1222 .cant_stop = true,
1223 },
1224 /* First state is scheduler control. Interrupts are disabled */
1225 [CPUHP_AP_SCHED_STARTING] = {
1226 .name = "sched:starting",
1227 .startup = sched_cpu_starting,
1228 .teardown = sched_cpu_dying,
1229 },
1230 /*
1231 * Low level startup/teardown notifiers. Run with interrupts
1232 * disabled. Will be removed once the notifiers are converted to
1233 * states.
1234 */
1235 [CPUHP_AP_NOTIFY_STARTING] = {
1236 .name = "notify:starting",
1237 .startup = notify_starting,
1238 .teardown = notify_dying,
1239 .skip_onerr = true,
1240 .cant_stop = true,
1241 },
1242 /* Entry state on starting. Interrupts enabled from here on. Transient
1243 * state for synchronsization */
1244 [CPUHP_AP_ONLINE] = {
1245 .name = "ap:online",
1246 },
1247 /* Handle smpboot threads park/unpark */
1248 [CPUHP_AP_SMPBOOT_THREADS] = {
1249 .name = "smpboot:threads",
1250 .startup = smpboot_unpark_threads,
1251 .teardown = NULL,
1252 },
1253 /*
1254 * Online/down_prepare notifiers. Will be removed once the notifiers
1255 * are converted to states.
1256 */
1257 [CPUHP_AP_NOTIFY_ONLINE] = {
1258 .name = "notify:online",
1259 .startup = notify_online,
1260 .teardown = notify_down_prepare,
1261 .skip_onerr = true,
1262 },
1263#endif
1264 /*
1265 * The dynamically registered state space is here
1266 */
1267
1268#ifdef CONFIG_SMP
1269 /* Last state is scheduler control setting the cpu active */
1270 [CPUHP_AP_ACTIVE] = {
1271 .name = "sched:active",
1272 .startup = sched_cpu_activate,
1273 .teardown = sched_cpu_deactivate,
1274 },
1275#endif
1276
1277 /* CPU is fully up and running. */
1278 [CPUHP_ONLINE] = {
1279 .name = "online",
1280 .startup = NULL,
1281 .teardown = NULL,
1282 },
1283};
1284
1285/* Sanity check for callbacks */
1286static int cpuhp_cb_check(enum cpuhp_state state)
1287{
1288 if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
1289 return -EINVAL;
1290 return 0;
1291}
1292
1293static bool cpuhp_is_ap_state(enum cpuhp_state state)
1294{
1295 /*
1296 * The extra check for CPUHP_TEARDOWN_CPU is only for documentation
1297 * purposes as that state is handled explicitely in cpu_down.
1298 */
1299 return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
1300}
1301
1302static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
1303{
1304 struct cpuhp_step *sp;
1305
1306 sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states;
1307 return sp + state;
1308}
1309
1310static void cpuhp_store_callbacks(enum cpuhp_state state,
1311 const char *name,
1312 int (*startup)(unsigned int cpu),
1313 int (*teardown)(unsigned int cpu))
1314{
1315 /* (Un)Install the callbacks for further cpu hotplug operations */
1316 struct cpuhp_step *sp;
1317
1318 mutex_lock(&cpuhp_state_mutex);
1319 sp = cpuhp_get_step(state);
1320 sp->startup = startup;
1321 sp->teardown = teardown;
1322 sp->name = name;
1323 mutex_unlock(&cpuhp_state_mutex);
1324}
1325
1326static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
1327{
1328 return cpuhp_get_step(state)->teardown;
1329}
1330
1331/*
1332 * Call the startup/teardown function for a step either on the AP or
1333 * on the current CPU.
1334 */
1335static int cpuhp_issue_call(int cpu, enum cpuhp_state state,
1336 int (*cb)(unsigned int), bool bringup)
1337{
1338 int ret;
1339
1340 if (!cb)
1341 return 0;
1342 /*
1343 * The non AP bound callbacks can fail on bringup. On teardown
1344 * e.g. module removal we crash for now.
1345 */
1346#ifdef CONFIG_SMP
1347 if (cpuhp_is_ap_state(state))
1348 ret = cpuhp_invoke_ap_callback(cpu, state, cb);
1349 else
1350 ret = cpuhp_invoke_callback(cpu, state, cb);
1351#else
1352 ret = cpuhp_invoke_callback(cpu, state, cb);
1353#endif
1354 BUG_ON(ret && !bringup);
1355 return ret;
1356}
1357
1358/*
1359 * Called from __cpuhp_setup_state on a recoverable failure.
1360 *
1361 * Note: The teardown callbacks for rollback are not allowed to fail!
1362 */
1363static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
1364 int (*teardown)(unsigned int cpu))
1365{
1366 int cpu;
1367
1368 if (!teardown)
1369 return;
1370
1371 /* Roll back the already executed steps on the other cpus */
1372 for_each_present_cpu(cpu) {
1373 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1374 int cpustate = st->state;
1375
1376 if (cpu >= failedcpu)
1377 break;
1378
1379 /* Did we invoke the startup call on that cpu ? */
1380 if (cpustate >= state)
1381 cpuhp_issue_call(cpu, state, teardown, false);
1382 }
1383}
1384
1385/*
1386 * Returns a free for dynamic slot assignment of the Online state. The states
1387 * are protected by the cpuhp_slot_states mutex and an empty slot is identified
1388 * by having no name assigned.
1389 */
1390static int cpuhp_reserve_state(enum cpuhp_state state)
1391{
1392 enum cpuhp_state i;
1393
1394 mutex_lock(&cpuhp_state_mutex);
1395 for (i = CPUHP_AP_ONLINE_DYN; i <= CPUHP_AP_ONLINE_DYN_END; i++) {
1396 if (cpuhp_ap_states[i].name)
1397 continue;
1398
1399 cpuhp_ap_states[i].name = "Reserved";
1400 mutex_unlock(&cpuhp_state_mutex);
1401 return i;
1402 }
1403 mutex_unlock(&cpuhp_state_mutex);
1404 WARN(1, "No more dynamic states available for CPU hotplug\n");
1405 return -ENOSPC;
1406}
1407
1408/**
1409 * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state
1410 * @state: The state to setup
1411 * @invoke: If true, the startup function is invoked for cpus where
1412 * cpu state >= @state
1413 * @startup: startup callback function
1414 * @teardown: teardown callback function
1415 *
1416 * Returns 0 if successful, otherwise a proper error code
1417 */
1418int __cpuhp_setup_state(enum cpuhp_state state,
1419 const char *name, bool invoke,
1420 int (*startup)(unsigned int cpu),
1421 int (*teardown)(unsigned int cpu))
1422{
1423 int cpu, ret = 0;
1424 int dyn_state = 0;
1425
1426 if (cpuhp_cb_check(state) || !name)
1427 return -EINVAL;
1428
1429 get_online_cpus();
1430
1431 /* currently assignments for the ONLINE state are possible */
1432 if (state == CPUHP_AP_ONLINE_DYN) {
1433 dyn_state = 1;
1434 ret = cpuhp_reserve_state(state);
1435 if (ret < 0)
1436 goto out;
1437 state = ret;
1438 }
1439
1440 cpuhp_store_callbacks(state, name, startup, teardown);
1441
1442 if (!invoke || !startup)
1443 goto out;
1444
1445 /*
1446 * Try to call the startup callback for each present cpu
1447 * depending on the hotplug state of the cpu.
1448 */
1449 for_each_present_cpu(cpu) {
1450 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1451 int cpustate = st->state;
1452
1453 if (cpustate < state)
1454 continue;
1455
1456 ret = cpuhp_issue_call(cpu, state, startup, true);
1457 if (ret) {
1458 cpuhp_rollback_install(cpu, state, teardown);
1459 cpuhp_store_callbacks(state, NULL, NULL, NULL);
1460 goto out;
1461 }
1462 }
1463out:
1464 put_online_cpus();
1465 if (!ret && dyn_state)
1466 return state;
1467 return ret;
1468}
1469EXPORT_SYMBOL(__cpuhp_setup_state);
1470
1471/**
1472 * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state
1473 * @state: The state to remove
1474 * @invoke: If true, the teardown function is invoked for cpus where
1475 * cpu state >= @state
1476 *
1477 * The teardown callback is currently not allowed to fail. Think
1478 * about module removal!
1479 */
1480void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
1481{
1482 int (*teardown)(unsigned int cpu) = cpuhp_get_teardown_cb(state);
1483 int cpu;
1484
1485 BUG_ON(cpuhp_cb_check(state));
1486
1487 get_online_cpus();
1488
1489 if (!invoke || !teardown)
1490 goto remove;
1491
1492 /*
1493 * Call the teardown callback for each present cpu depending
1494 * on the hotplug state of the cpu. This function is not
1495 * allowed to fail currently!
1496 */
1497 for_each_present_cpu(cpu) {
1498 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1499 int cpustate = st->state;
1500
1501 if (cpustate >= state)
1502 cpuhp_issue_call(cpu, state, teardown, false);
1503 }
1504remove:
1505 cpuhp_store_callbacks(state, NULL, NULL, NULL);
1506 put_online_cpus();
1507}
1508EXPORT_SYMBOL(__cpuhp_remove_state);
1509
1510#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
1511static ssize_t show_cpuhp_state(struct device *dev,
1512 struct device_attribute *attr, char *buf)
1513{
1514 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1515
1516 return sprintf(buf, "%d\n", st->state);
1517}
1518static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
1519
1520static ssize_t write_cpuhp_target(struct device *dev,
1521 struct device_attribute *attr,
1522 const char *buf, size_t count)
1523{
1524 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1525 struct cpuhp_step *sp;
1526 int target, ret;
1527
1528 ret = kstrtoint(buf, 10, &target);
1529 if (ret)
1530 return ret;
1531
1532#ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
1533 if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
1534 return -EINVAL;
1535#else
1536 if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
1537 return -EINVAL;
1538#endif
1539
1540 ret = lock_device_hotplug_sysfs();
1541 if (ret)
1542 return ret;
1543
1544 mutex_lock(&cpuhp_state_mutex);
1545 sp = cpuhp_get_step(target);
1546 ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
1547 mutex_unlock(&cpuhp_state_mutex);
1548 if (ret)
1549 return ret;
1550
1551 if (st->state < target)
1552 ret = do_cpu_up(dev->id, target);
1553 else
1554 ret = do_cpu_down(dev->id, target);
1555
1556 unlock_device_hotplug();
1557 return ret ? ret : count;
1558}
1559
1560static ssize_t show_cpuhp_target(struct device *dev,
1561 struct device_attribute *attr, char *buf)
1562{
1563 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1564
1565 return sprintf(buf, "%d\n", st->target);
1566}
1567static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
1568
1569static struct attribute *cpuhp_cpu_attrs[] = {
1570 &dev_attr_state.attr,
1571 &dev_attr_target.attr,
1572 NULL
1573};
1574
1575static struct attribute_group cpuhp_cpu_attr_group = {
1576 .attrs = cpuhp_cpu_attrs,
1577 .name = "hotplug",
1578 NULL
1579};
1580
1581static ssize_t show_cpuhp_states(struct device *dev,
1582 struct device_attribute *attr, char *buf)
1583{
1584 ssize_t cur, res = 0;
1585 int i;
1586
1587 mutex_lock(&cpuhp_state_mutex);
1588 for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
1589 struct cpuhp_step *sp = cpuhp_get_step(i);
1590
1591 if (sp->name) {
1592 cur = sprintf(buf, "%3d: %s\n", i, sp->name);
1593 buf += cur;
1594 res += cur;
1595 }
1596 }
1597 mutex_unlock(&cpuhp_state_mutex);
1598 return res;
1599}
1600static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);
1601
1602static struct attribute *cpuhp_cpu_root_attrs[] = {
1603 &dev_attr_states.attr,
1604 NULL
1605};
1606
1607static struct attribute_group cpuhp_cpu_root_attr_group = {
1608 .attrs = cpuhp_cpu_root_attrs,
1609 .name = "hotplug",
1610 NULL
1611};
1612
1613static int __init cpuhp_sysfs_init(void)
1614{
1615 int cpu, ret;
1616
1617 ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
1618 &cpuhp_cpu_root_attr_group);
1619 if (ret)
1620 return ret;
1621
1622 for_each_possible_cpu(cpu) {
1623 struct device *dev = get_cpu_device(cpu);
1624
1625 if (!dev)
1626 continue;
1627 ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);
1628 if (ret)
1629 return ret;
1630 }
1631 return 0;
1632}
1633device_initcall(cpuhp_sysfs_init);
1634#endif
1635
1636/*
1637 * cpu_bit_bitmap[] is a special, "compressed" data structure that
1638 * represents all NR_CPUS bits binary values of 1<<nr.
1639 *
1640 * It is used by cpumask_of() to get a constant address to a CPU
1641 * mask value that has a single bit set only.
1642 */
1643
1644/* cpu_bit_bitmap[0] is empty - so we can back into it */
1645#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
1646#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
1647#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
1648#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
1649
1650const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
1651
1652 MASK_DECLARE_8(0), MASK_DECLARE_8(8),
1653 MASK_DECLARE_8(16), MASK_DECLARE_8(24),
1654#if BITS_PER_LONG > 32
1655 MASK_DECLARE_8(32), MASK_DECLARE_8(40),
1656 MASK_DECLARE_8(48), MASK_DECLARE_8(56),
1657#endif
1658};
1659EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
1660
1661const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
1662EXPORT_SYMBOL(cpu_all_bits);
1663
1664#ifdef CONFIG_INIT_ALL_POSSIBLE
1665struct cpumask __cpu_possible_mask __read_mostly
1666 = {CPU_BITS_ALL};
1667#else
1668struct cpumask __cpu_possible_mask __read_mostly;
1669#endif
1670EXPORT_SYMBOL(__cpu_possible_mask);
1671
1672struct cpumask __cpu_online_mask __read_mostly;
1673EXPORT_SYMBOL(__cpu_online_mask);
1674
1675struct cpumask __cpu_present_mask __read_mostly;
1676EXPORT_SYMBOL(__cpu_present_mask);
1677
1678struct cpumask __cpu_active_mask __read_mostly;
1679EXPORT_SYMBOL(__cpu_active_mask);
1680
1681void init_cpu_present(const struct cpumask *src)
1682{
1683 cpumask_copy(&__cpu_present_mask, src);
1684}
1685
1686void init_cpu_possible(const struct cpumask *src)
1687{
1688 cpumask_copy(&__cpu_possible_mask, src);
1689}
1690
1691void init_cpu_online(const struct cpumask *src)
1692{
1693 cpumask_copy(&__cpu_online_mask, src);
1694}
1695
1696/*
1697 * Activate the first processor.
1698 */
1699void __init boot_cpu_init(void)
1700{
1701 int cpu = smp_processor_id();
1702
1703 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
1704 set_cpu_online(cpu, true);
1705 set_cpu_active(cpu, true);
1706 set_cpu_present(cpu, true);
1707 set_cpu_possible(cpu, true);
1708}
1709
1710/*
1711 * Must be called _AFTER_ setting up the per_cpu areas
1712 */
1713void __init boot_cpu_state_init(void)
1714{
1715 per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
1716}