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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 /*
707 * By now we've cleared cpu_active_mask, wait for all preempt-disabled
708 * and RCU users of this state to go away such that all new such users
709 * will observe it.
710 *
711 * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
712 * not imply sync_sched(), so wait for both.
713 *
714 * Do sync before park smpboot threads to take care the rcu boost case.
715 */
716 if (IS_ENABLED(CONFIG_PREEMPT))
717 synchronize_rcu_mult(call_rcu, call_rcu_sched);
718 else
719 synchronize_rcu();
720
721 /* Park the smpboot threads */
722 kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread);
723 smpboot_park_threads(cpu);
724
725 /*
726 * Prevent irq alloc/free while the dying cpu reorganizes the
727 * interrupt affinities.
728 */
729 irq_lock_sparse();
730
731 /*
732 * So now all preempt/rcu users must observe !cpu_active().
733 */
734 err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu));
735 if (err) {
736 /* CPU refused to die */
737 irq_unlock_sparse();
738 /* Unpark the hotplug thread so we can rollback there */
739 kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread);
740 return err;
741 }
742 BUG_ON(cpu_online(cpu));
743
744 /*
745 * The migration_call() CPU_DYING callback will have removed all
746 * runnable tasks from the cpu, there's only the idle task left now
747 * that the migration thread is done doing the stop_machine thing.
748 *
749 * Wait for the stop thread to go away.
750 */
751 wait_for_completion(&st->done);
752 BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
753
754 /* Interrupts are moved away from the dying cpu, reenable alloc/free */
755 irq_unlock_sparse();
756
757 hotplug_cpu__broadcast_tick_pull(cpu);
758 /* This actually kills the CPU. */
759 __cpu_die(cpu);
760
761 tick_cleanup_dead_cpu(cpu);
762 return 0;
763}
764
765static int notify_dead(unsigned int cpu)
766{
767 cpu_notify_nofail(CPU_DEAD, cpu);
768 check_for_tasks(cpu);
769 return 0;
770}
771
772static void cpuhp_complete_idle_dead(void *arg)
773{
774 struct cpuhp_cpu_state *st = arg;
775
776 complete(&st->done);
777}
778
779void cpuhp_report_idle_dead(void)
780{
781 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
782
783 BUG_ON(st->state != CPUHP_AP_OFFLINE);
784 rcu_report_dead(smp_processor_id());
785 st->state = CPUHP_AP_IDLE_DEAD;
786 /*
787 * We cannot call complete after rcu_report_dead() so we delegate it
788 * to an online cpu.
789 */
790 smp_call_function_single(cpumask_first(cpu_online_mask),
791 cpuhp_complete_idle_dead, st, 0);
792}
793
794#else
795#define notify_down_prepare NULL
796#define takedown_cpu NULL
797#define notify_dead NULL
798#define notify_dying NULL
799#endif
800
801#ifdef CONFIG_HOTPLUG_CPU
802
803/* Requires cpu_add_remove_lock to be held */
804static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
805 enum cpuhp_state target)
806{
807 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
808 int prev_state, ret = 0;
809 bool hasdied = false;
810
811 if (num_online_cpus() == 1)
812 return -EBUSY;
813
814 if (!cpu_present(cpu))
815 return -EINVAL;
816
817 cpu_hotplug_begin();
818
819 cpuhp_tasks_frozen = tasks_frozen;
820
821 prev_state = st->state;
822 st->target = target;
823 /*
824 * If the current CPU state is in the range of the AP hotplug thread,
825 * then we need to kick the thread.
826 */
827 if (st->state > CPUHP_TEARDOWN_CPU) {
828 ret = cpuhp_kick_ap_work(cpu);
829 /*
830 * The AP side has done the error rollback already. Just
831 * return the error code..
832 */
833 if (ret)
834 goto out;
835
836 /*
837 * We might have stopped still in the range of the AP hotplug
838 * thread. Nothing to do anymore.
839 */
840 if (st->state > CPUHP_TEARDOWN_CPU)
841 goto out;
842 }
843 /*
844 * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need
845 * to do the further cleanups.
846 */
847 ret = cpuhp_down_callbacks(cpu, st, cpuhp_bp_states, target);
848 if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) {
849 st->target = prev_state;
850 st->rollback = true;
851 cpuhp_kick_ap_work(cpu);
852 }
853
854 hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE;
855out:
856 cpu_hotplug_done();
857 /* This post dead nonsense must die */
858 if (!ret && hasdied)
859 cpu_notify_nofail(CPU_POST_DEAD, cpu);
860 return ret;
861}
862
863static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
864{
865 int err;
866
867 cpu_maps_update_begin();
868
869 if (cpu_hotplug_disabled) {
870 err = -EBUSY;
871 goto out;
872 }
873
874 err = _cpu_down(cpu, 0, target);
875
876out:
877 cpu_maps_update_done();
878 return err;
879}
880int cpu_down(unsigned int cpu)
881{
882 return do_cpu_down(cpu, CPUHP_OFFLINE);
883}
884EXPORT_SYMBOL(cpu_down);
885#endif /*CONFIG_HOTPLUG_CPU*/
886
887/**
888 * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
889 * @cpu: cpu that just started
890 *
891 * This function calls the cpu_chain notifiers with CPU_STARTING.
892 * It must be called by the arch code on the new cpu, before the new cpu
893 * enables interrupts and before the "boot" cpu returns from __cpu_up().
894 */
895void notify_cpu_starting(unsigned int cpu)
896{
897 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
898 enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
899
900 while (st->state < target) {
901 struct cpuhp_step *step;
902
903 st->state++;
904 step = cpuhp_ap_states + st->state;
905 cpuhp_invoke_callback(cpu, st->state, step->startup);
906 }
907}
908
909/*
910 * Called from the idle task. We need to set active here, so we can kick off
911 * the stopper thread and unpark the smpboot threads. If the target state is
912 * beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the
913 * cpu further.
914 */
915void cpuhp_online_idle(enum cpuhp_state state)
916{
917 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
918 unsigned int cpu = smp_processor_id();
919
920 /* Happens for the boot cpu */
921 if (state != CPUHP_AP_ONLINE_IDLE)
922 return;
923
924 st->state = CPUHP_AP_ONLINE_IDLE;
925
926 /* The cpu is marked online, set it active now */
927 set_cpu_active(cpu, true);
928 /* Unpark the stopper thread and the hotplug thread of this cpu */
929 stop_machine_unpark(cpu);
930 kthread_unpark(st->thread);
931
932 /* Should we go further up ? */
933 if (st->target > CPUHP_AP_ONLINE_IDLE)
934 __cpuhp_kick_ap_work(st);
935 else
936 complete(&st->done);
937}
938
939/* Requires cpu_add_remove_lock to be held */
940static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
941{
942 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
943 struct task_struct *idle;
944 int ret = 0;
945
946 cpu_hotplug_begin();
947
948 if (!cpu_present(cpu)) {
949 ret = -EINVAL;
950 goto out;
951 }
952
953 /*
954 * The caller of do_cpu_up might have raced with another
955 * caller. Ignore it for now.
956 */
957 if (st->state >= target)
958 goto out;
959
960 if (st->state == CPUHP_OFFLINE) {
961 /* Let it fail before we try to bring the cpu up */
962 idle = idle_thread_get(cpu);
963 if (IS_ERR(idle)) {
964 ret = PTR_ERR(idle);
965 goto out;
966 }
967 }
968
969 cpuhp_tasks_frozen = tasks_frozen;
970
971 st->target = target;
972 /*
973 * If the current CPU state is in the range of the AP hotplug thread,
974 * then we need to kick the thread once more.
975 */
976 if (st->state > CPUHP_BRINGUP_CPU) {
977 ret = cpuhp_kick_ap_work(cpu);
978 /*
979 * The AP side has done the error rollback already. Just
980 * return the error code..
981 */
982 if (ret)
983 goto out;
984 }
985
986 /*
987 * Try to reach the target state. We max out on the BP at
988 * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
989 * responsible for bringing it up to the target state.
990 */
991 target = min((int)target, CPUHP_BRINGUP_CPU);
992 ret = cpuhp_up_callbacks(cpu, st, cpuhp_bp_states, target);
993out:
994 cpu_hotplug_done();
995 return ret;
996}
997
998static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
999{
1000 int err = 0;
1001
1002 if (!cpu_possible(cpu)) {
1003 pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
1004 cpu);
1005#if defined(CONFIG_IA64)
1006 pr_err("please check additional_cpus= boot parameter\n");
1007#endif
1008 return -EINVAL;
1009 }
1010
1011 err = try_online_node(cpu_to_node(cpu));
1012 if (err)
1013 return err;
1014
1015 cpu_maps_update_begin();
1016
1017 if (cpu_hotplug_disabled) {
1018 err = -EBUSY;
1019 goto out;
1020 }
1021
1022 err = _cpu_up(cpu, 0, target);
1023out:
1024 cpu_maps_update_done();
1025 return err;
1026}
1027
1028int cpu_up(unsigned int cpu)
1029{
1030 return do_cpu_up(cpu, CPUHP_ONLINE);
1031}
1032EXPORT_SYMBOL_GPL(cpu_up);
1033
1034#ifdef CONFIG_PM_SLEEP_SMP
1035static cpumask_var_t frozen_cpus;
1036
1037int disable_nonboot_cpus(void)
1038{
1039 int cpu, first_cpu, error = 0;
1040
1041 cpu_maps_update_begin();
1042 first_cpu = cpumask_first(cpu_online_mask);
1043 /*
1044 * We take down all of the non-boot CPUs in one shot to avoid races
1045 * with the userspace trying to use the CPU hotplug at the same time
1046 */
1047 cpumask_clear(frozen_cpus);
1048
1049 pr_info("Disabling non-boot CPUs ...\n");
1050 for_each_online_cpu(cpu) {
1051 if (cpu == first_cpu)
1052 continue;
1053 trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
1054 error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
1055 trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
1056 if (!error)
1057 cpumask_set_cpu(cpu, frozen_cpus);
1058 else {
1059 pr_err("Error taking CPU%d down: %d\n", cpu, error);
1060 break;
1061 }
1062 }
1063
1064 if (!error)
1065 BUG_ON(num_online_cpus() > 1);
1066 else
1067 pr_err("Non-boot CPUs are not disabled\n");
1068
1069 /*
1070 * Make sure the CPUs won't be enabled by someone else. We need to do
1071 * this even in case of failure as all disable_nonboot_cpus() users are
1072 * supposed to do enable_nonboot_cpus() on the failure path.
1073 */
1074 cpu_hotplug_disabled++;
1075
1076 cpu_maps_update_done();
1077 return error;
1078}
1079
1080void __weak arch_enable_nonboot_cpus_begin(void)
1081{
1082}
1083
1084void __weak arch_enable_nonboot_cpus_end(void)
1085{
1086}
1087
1088void enable_nonboot_cpus(void)
1089{
1090 int cpu, error;
1091
1092 /* Allow everyone to use the CPU hotplug again */
1093 cpu_maps_update_begin();
1094 WARN_ON(--cpu_hotplug_disabled < 0);
1095 if (cpumask_empty(frozen_cpus))
1096 goto out;
1097
1098 pr_info("Enabling non-boot CPUs ...\n");
1099
1100 arch_enable_nonboot_cpus_begin();
1101
1102 for_each_cpu(cpu, frozen_cpus) {
1103 trace_suspend_resume(TPS("CPU_ON"), cpu, true);
1104 error = _cpu_up(cpu, 1, CPUHP_ONLINE);
1105 trace_suspend_resume(TPS("CPU_ON"), cpu, false);
1106 if (!error) {
1107 pr_info("CPU%d is up\n", cpu);
1108 continue;
1109 }
1110 pr_warn("Error taking CPU%d up: %d\n", cpu, error);
1111 }
1112
1113 arch_enable_nonboot_cpus_end();
1114
1115 cpumask_clear(frozen_cpus);
1116out:
1117 cpu_maps_update_done();
1118}
1119
1120static int __init alloc_frozen_cpus(void)
1121{
1122 if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
1123 return -ENOMEM;
1124 return 0;
1125}
1126core_initcall(alloc_frozen_cpus);
1127
1128/*
1129 * When callbacks for CPU hotplug notifications are being executed, we must
1130 * ensure that the state of the system with respect to the tasks being frozen
1131 * or not, as reported by the notification, remains unchanged *throughout the
1132 * duration* of the execution of the callbacks.
1133 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
1134 *
1135 * This synchronization is implemented by mutually excluding regular CPU
1136 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
1137 * Hibernate notifications.
1138 */
1139static int
1140cpu_hotplug_pm_callback(struct notifier_block *nb,
1141 unsigned long action, void *ptr)
1142{
1143 switch (action) {
1144
1145 case PM_SUSPEND_PREPARE:
1146 case PM_HIBERNATION_PREPARE:
1147 cpu_hotplug_disable();
1148 break;
1149
1150 case PM_POST_SUSPEND:
1151 case PM_POST_HIBERNATION:
1152 cpu_hotplug_enable();
1153 break;
1154
1155 default:
1156 return NOTIFY_DONE;
1157 }
1158
1159 return NOTIFY_OK;
1160}
1161
1162
1163static int __init cpu_hotplug_pm_sync_init(void)
1164{
1165 /*
1166 * cpu_hotplug_pm_callback has higher priority than x86
1167 * bsp_pm_callback which depends on cpu_hotplug_pm_callback
1168 * to disable cpu hotplug to avoid cpu hotplug race.
1169 */
1170 pm_notifier(cpu_hotplug_pm_callback, 0);
1171 return 0;
1172}
1173core_initcall(cpu_hotplug_pm_sync_init);
1174
1175#endif /* CONFIG_PM_SLEEP_SMP */
1176
1177#endif /* CONFIG_SMP */
1178
1179/* Boot processor state steps */
1180static struct cpuhp_step cpuhp_bp_states[] = {
1181 [CPUHP_OFFLINE] = {
1182 .name = "offline",
1183 .startup = NULL,
1184 .teardown = NULL,
1185 },
1186#ifdef CONFIG_SMP
1187 [CPUHP_CREATE_THREADS]= {
1188 .name = "threads:create",
1189 .startup = smpboot_create_threads,
1190 .teardown = NULL,
1191 .cant_stop = true,
1192 },
1193 /*
1194 * Preparatory and dead notifiers. Will be replaced once the notifiers
1195 * are converted to states.
1196 */
1197 [CPUHP_NOTIFY_PREPARE] = {
1198 .name = "notify:prepare",
1199 .startup = notify_prepare,
1200 .teardown = notify_dead,
1201 .skip_onerr = true,
1202 .cant_stop = true,
1203 },
1204 /* Kicks the plugged cpu into life */
1205 [CPUHP_BRINGUP_CPU] = {
1206 .name = "cpu:bringup",
1207 .startup = bringup_cpu,
1208 .teardown = NULL,
1209 .cant_stop = true,
1210 },
1211 /*
1212 * Handled on controll processor until the plugged processor manages
1213 * this itself.
1214 */
1215 [CPUHP_TEARDOWN_CPU] = {
1216 .name = "cpu:teardown",
1217 .startup = NULL,
1218 .teardown = takedown_cpu,
1219 .cant_stop = true,
1220 },
1221#endif
1222};
1223
1224/* Application processor state steps */
1225static struct cpuhp_step cpuhp_ap_states[] = {
1226#ifdef CONFIG_SMP
1227 /* Final state before CPU kills itself */
1228 [CPUHP_AP_IDLE_DEAD] = {
1229 .name = "idle:dead",
1230 },
1231 /*
1232 * Last state before CPU enters the idle loop to die. Transient state
1233 * for synchronization.
1234 */
1235 [CPUHP_AP_OFFLINE] = {
1236 .name = "ap:offline",
1237 .cant_stop = true,
1238 },
1239 /*
1240 * Low level startup/teardown notifiers. Run with interrupts
1241 * disabled. Will be removed once the notifiers are converted to
1242 * states.
1243 */
1244 [CPUHP_AP_NOTIFY_STARTING] = {
1245 .name = "notify:starting",
1246 .startup = notify_starting,
1247 .teardown = notify_dying,
1248 .skip_onerr = true,
1249 .cant_stop = true,
1250 },
1251 /* Entry state on starting. Interrupts enabled from here on. Transient
1252 * state for synchronsization */
1253 [CPUHP_AP_ONLINE] = {
1254 .name = "ap:online",
1255 },
1256 /* Handle smpboot threads park/unpark */
1257 [CPUHP_AP_SMPBOOT_THREADS] = {
1258 .name = "smpboot:threads",
1259 .startup = smpboot_unpark_threads,
1260 .teardown = NULL,
1261 },
1262 /*
1263 * Online/down_prepare notifiers. Will be removed once the notifiers
1264 * are converted to states.
1265 */
1266 [CPUHP_AP_NOTIFY_ONLINE] = {
1267 .name = "notify:online",
1268 .startup = notify_online,
1269 .teardown = notify_down_prepare,
1270 .skip_onerr = true,
1271 },
1272#endif
1273 /*
1274 * The dynamically registered state space is here
1275 */
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}
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/signal.h>
11#include <linux/sched/hotplug.h>
12#include <linux/sched/task.h>
13#include <linux/unistd.h>
14#include <linux/cpu.h>
15#include <linux/oom.h>
16#include <linux/rcupdate.h>
17#include <linux/export.h>
18#include <linux/bug.h>
19#include <linux/kthread.h>
20#include <linux/stop_machine.h>
21#include <linux/mutex.h>
22#include <linux/gfp.h>
23#include <linux/suspend.h>
24#include <linux/lockdep.h>
25#include <linux/tick.h>
26#include <linux/irq.h>
27#include <linux/nmi.h>
28#include <linux/smpboot.h>
29#include <linux/relay.h>
30#include <linux/slab.h>
31#include <linux/percpu-rwsem.h>
32
33#include <trace/events/power.h>
34#define CREATE_TRACE_POINTS
35#include <trace/events/cpuhp.h>
36
37#include "smpboot.h"
38
39/**
40 * cpuhp_cpu_state - Per cpu hotplug state storage
41 * @state: The current cpu state
42 * @target: The target state
43 * @thread: Pointer to the hotplug thread
44 * @should_run: Thread should execute
45 * @rollback: Perform a rollback
46 * @single: Single callback invocation
47 * @bringup: Single callback bringup or teardown selector
48 * @cb_state: The state for a single callback (install/uninstall)
49 * @result: Result of the operation
50 * @done_up: Signal completion to the issuer of the task for cpu-up
51 * @done_down: Signal completion to the issuer of the task for cpu-down
52 */
53struct cpuhp_cpu_state {
54 enum cpuhp_state state;
55 enum cpuhp_state target;
56 enum cpuhp_state fail;
57#ifdef CONFIG_SMP
58 struct task_struct *thread;
59 bool should_run;
60 bool rollback;
61 bool single;
62 bool bringup;
63 struct hlist_node *node;
64 struct hlist_node *last;
65 enum cpuhp_state cb_state;
66 int result;
67 struct completion done_up;
68 struct completion done_down;
69#endif
70};
71
72static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = {
73 .fail = CPUHP_INVALID,
74};
75
76#if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP)
77static struct lockdep_map cpuhp_state_up_map =
78 STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map);
79static struct lockdep_map cpuhp_state_down_map =
80 STATIC_LOCKDEP_MAP_INIT("cpuhp_state-down", &cpuhp_state_down_map);
81
82
83static inline void cpuhp_lock_acquire(bool bringup)
84{
85 lock_map_acquire(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map);
86}
87
88static inline void cpuhp_lock_release(bool bringup)
89{
90 lock_map_release(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map);
91}
92#else
93
94static inline void cpuhp_lock_acquire(bool bringup) { }
95static inline void cpuhp_lock_release(bool bringup) { }
96
97#endif
98
99/**
100 * cpuhp_step - Hotplug state machine step
101 * @name: Name of the step
102 * @startup: Startup function of the step
103 * @teardown: Teardown function of the step
104 * @skip_onerr: Do not invoke the functions on error rollback
105 * Will go away once the notifiers are gone
106 * @cant_stop: Bringup/teardown can't be stopped at this step
107 */
108struct cpuhp_step {
109 const char *name;
110 union {
111 int (*single)(unsigned int cpu);
112 int (*multi)(unsigned int cpu,
113 struct hlist_node *node);
114 } startup;
115 union {
116 int (*single)(unsigned int cpu);
117 int (*multi)(unsigned int cpu,
118 struct hlist_node *node);
119 } teardown;
120 struct hlist_head list;
121 bool skip_onerr;
122 bool cant_stop;
123 bool multi_instance;
124};
125
126static DEFINE_MUTEX(cpuhp_state_mutex);
127static struct cpuhp_step cpuhp_hp_states[];
128
129static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
130{
131 return cpuhp_hp_states + state;
132}
133
134/**
135 * cpuhp_invoke_callback _ Invoke the callbacks for a given state
136 * @cpu: The cpu for which the callback should be invoked
137 * @state: The state to do callbacks for
138 * @bringup: True if the bringup callback should be invoked
139 * @node: For multi-instance, do a single entry callback for install/remove
140 * @lastp: For multi-instance rollback, remember how far we got
141 *
142 * Called from cpu hotplug and from the state register machinery.
143 */
144static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
145 bool bringup, struct hlist_node *node,
146 struct hlist_node **lastp)
147{
148 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
149 struct cpuhp_step *step = cpuhp_get_step(state);
150 int (*cbm)(unsigned int cpu, struct hlist_node *node);
151 int (*cb)(unsigned int cpu);
152 int ret, cnt;
153
154 if (st->fail == state) {
155 st->fail = CPUHP_INVALID;
156
157 if (!(bringup ? step->startup.single : step->teardown.single))
158 return 0;
159
160 return -EAGAIN;
161 }
162
163 if (!step->multi_instance) {
164 WARN_ON_ONCE(lastp && *lastp);
165 cb = bringup ? step->startup.single : step->teardown.single;
166 if (!cb)
167 return 0;
168 trace_cpuhp_enter(cpu, st->target, state, cb);
169 ret = cb(cpu);
170 trace_cpuhp_exit(cpu, st->state, state, ret);
171 return ret;
172 }
173 cbm = bringup ? step->startup.multi : step->teardown.multi;
174 if (!cbm)
175 return 0;
176
177 /* Single invocation for instance add/remove */
178 if (node) {
179 WARN_ON_ONCE(lastp && *lastp);
180 trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
181 ret = cbm(cpu, node);
182 trace_cpuhp_exit(cpu, st->state, state, ret);
183 return ret;
184 }
185
186 /* State transition. Invoke on all instances */
187 cnt = 0;
188 hlist_for_each(node, &step->list) {
189 if (lastp && node == *lastp)
190 break;
191
192 trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
193 ret = cbm(cpu, node);
194 trace_cpuhp_exit(cpu, st->state, state, ret);
195 if (ret) {
196 if (!lastp)
197 goto err;
198
199 *lastp = node;
200 return ret;
201 }
202 cnt++;
203 }
204 if (lastp)
205 *lastp = NULL;
206 return 0;
207err:
208 /* Rollback the instances if one failed */
209 cbm = !bringup ? step->startup.multi : step->teardown.multi;
210 if (!cbm)
211 return ret;
212
213 hlist_for_each(node, &step->list) {
214 if (!cnt--)
215 break;
216
217 trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
218 ret = cbm(cpu, node);
219 trace_cpuhp_exit(cpu, st->state, state, ret);
220 /*
221 * Rollback must not fail,
222 */
223 WARN_ON_ONCE(ret);
224 }
225 return ret;
226}
227
228#ifdef CONFIG_SMP
229static bool cpuhp_is_ap_state(enum cpuhp_state state)
230{
231 /*
232 * The extra check for CPUHP_TEARDOWN_CPU is only for documentation
233 * purposes as that state is handled explicitly in cpu_down.
234 */
235 return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
236}
237
238static inline void wait_for_ap_thread(struct cpuhp_cpu_state *st, bool bringup)
239{
240 struct completion *done = bringup ? &st->done_up : &st->done_down;
241 wait_for_completion(done);
242}
243
244static inline void complete_ap_thread(struct cpuhp_cpu_state *st, bool bringup)
245{
246 struct completion *done = bringup ? &st->done_up : &st->done_down;
247 complete(done);
248}
249
250/*
251 * The former STARTING/DYING states, ran with IRQs disabled and must not fail.
252 */
253static bool cpuhp_is_atomic_state(enum cpuhp_state state)
254{
255 return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE;
256}
257
258/* Serializes the updates to cpu_online_mask, cpu_present_mask */
259static DEFINE_MUTEX(cpu_add_remove_lock);
260bool cpuhp_tasks_frozen;
261EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen);
262
263/*
264 * The following two APIs (cpu_maps_update_begin/done) must be used when
265 * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
266 */
267void cpu_maps_update_begin(void)
268{
269 mutex_lock(&cpu_add_remove_lock);
270}
271
272void cpu_maps_update_done(void)
273{
274 mutex_unlock(&cpu_add_remove_lock);
275}
276
277/*
278 * If set, cpu_up and cpu_down will return -EBUSY and do nothing.
279 * Should always be manipulated under cpu_add_remove_lock
280 */
281static int cpu_hotplug_disabled;
282
283#ifdef CONFIG_HOTPLUG_CPU
284
285DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock);
286
287void cpus_read_lock(void)
288{
289 percpu_down_read(&cpu_hotplug_lock);
290}
291EXPORT_SYMBOL_GPL(cpus_read_lock);
292
293void cpus_read_unlock(void)
294{
295 percpu_up_read(&cpu_hotplug_lock);
296}
297EXPORT_SYMBOL_GPL(cpus_read_unlock);
298
299void cpus_write_lock(void)
300{
301 percpu_down_write(&cpu_hotplug_lock);
302}
303
304void cpus_write_unlock(void)
305{
306 percpu_up_write(&cpu_hotplug_lock);
307}
308
309void lockdep_assert_cpus_held(void)
310{
311 percpu_rwsem_assert_held(&cpu_hotplug_lock);
312}
313
314/*
315 * Wait for currently running CPU hotplug operations to complete (if any) and
316 * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
317 * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
318 * hotplug path before performing hotplug operations. So acquiring that lock
319 * guarantees mutual exclusion from any currently running hotplug operations.
320 */
321void cpu_hotplug_disable(void)
322{
323 cpu_maps_update_begin();
324 cpu_hotplug_disabled++;
325 cpu_maps_update_done();
326}
327EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
328
329static void __cpu_hotplug_enable(void)
330{
331 if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
332 return;
333 cpu_hotplug_disabled--;
334}
335
336void cpu_hotplug_enable(void)
337{
338 cpu_maps_update_begin();
339 __cpu_hotplug_enable();
340 cpu_maps_update_done();
341}
342EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
343#endif /* CONFIG_HOTPLUG_CPU */
344
345static inline enum cpuhp_state
346cpuhp_set_state(struct cpuhp_cpu_state *st, enum cpuhp_state target)
347{
348 enum cpuhp_state prev_state = st->state;
349
350 st->rollback = false;
351 st->last = NULL;
352
353 st->target = target;
354 st->single = false;
355 st->bringup = st->state < target;
356
357 return prev_state;
358}
359
360static inline void
361cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state)
362{
363 st->rollback = true;
364
365 /*
366 * If we have st->last we need to undo partial multi_instance of this
367 * state first. Otherwise start undo at the previous state.
368 */
369 if (!st->last) {
370 if (st->bringup)
371 st->state--;
372 else
373 st->state++;
374 }
375
376 st->target = prev_state;
377 st->bringup = !st->bringup;
378}
379
380/* Regular hotplug invocation of the AP hotplug thread */
381static void __cpuhp_kick_ap(struct cpuhp_cpu_state *st)
382{
383 if (!st->single && st->state == st->target)
384 return;
385
386 st->result = 0;
387 /*
388 * Make sure the above stores are visible before should_run becomes
389 * true. Paired with the mb() above in cpuhp_thread_fun()
390 */
391 smp_mb();
392 st->should_run = true;
393 wake_up_process(st->thread);
394 wait_for_ap_thread(st, st->bringup);
395}
396
397static int cpuhp_kick_ap(struct cpuhp_cpu_state *st, enum cpuhp_state target)
398{
399 enum cpuhp_state prev_state;
400 int ret;
401
402 prev_state = cpuhp_set_state(st, target);
403 __cpuhp_kick_ap(st);
404 if ((ret = st->result)) {
405 cpuhp_reset_state(st, prev_state);
406 __cpuhp_kick_ap(st);
407 }
408
409 return ret;
410}
411
412static int bringup_wait_for_ap(unsigned int cpu)
413{
414 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
415
416 /* Wait for the CPU to reach CPUHP_AP_ONLINE_IDLE */
417 wait_for_ap_thread(st, true);
418 if (WARN_ON_ONCE((!cpu_online(cpu))))
419 return -ECANCELED;
420
421 /* Unpark the stopper thread and the hotplug thread of the target cpu */
422 stop_machine_unpark(cpu);
423 kthread_unpark(st->thread);
424
425 if (st->target <= CPUHP_AP_ONLINE_IDLE)
426 return 0;
427
428 return cpuhp_kick_ap(st, st->target);
429}
430
431static int bringup_cpu(unsigned int cpu)
432{
433 struct task_struct *idle = idle_thread_get(cpu);
434 int ret;
435
436 /*
437 * Some architectures have to walk the irq descriptors to
438 * setup the vector space for the cpu which comes online.
439 * Prevent irq alloc/free across the bringup.
440 */
441 irq_lock_sparse();
442
443 /* Arch-specific enabling code. */
444 ret = __cpu_up(cpu, idle);
445 irq_unlock_sparse();
446 if (ret)
447 return ret;
448 return bringup_wait_for_ap(cpu);
449}
450
451/*
452 * Hotplug state machine related functions
453 */
454
455static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st)
456{
457 for (st->state--; st->state > st->target; st->state--) {
458 struct cpuhp_step *step = cpuhp_get_step(st->state);
459
460 if (!step->skip_onerr)
461 cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
462 }
463}
464
465static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
466 enum cpuhp_state target)
467{
468 enum cpuhp_state prev_state = st->state;
469 int ret = 0;
470
471 while (st->state < target) {
472 st->state++;
473 ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
474 if (ret) {
475 st->target = prev_state;
476 undo_cpu_up(cpu, st);
477 break;
478 }
479 }
480 return ret;
481}
482
483/*
484 * The cpu hotplug threads manage the bringup and teardown of the cpus
485 */
486static void cpuhp_create(unsigned int cpu)
487{
488 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
489
490 init_completion(&st->done_up);
491 init_completion(&st->done_down);
492}
493
494static int cpuhp_should_run(unsigned int cpu)
495{
496 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
497
498 return st->should_run;
499}
500
501/*
502 * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke
503 * callbacks when a state gets [un]installed at runtime.
504 *
505 * Each invocation of this function by the smpboot thread does a single AP
506 * state callback.
507 *
508 * It has 3 modes of operation:
509 * - single: runs st->cb_state
510 * - up: runs ++st->state, while st->state < st->target
511 * - down: runs st->state--, while st->state > st->target
512 *
513 * When complete or on error, should_run is cleared and the completion is fired.
514 */
515static void cpuhp_thread_fun(unsigned int cpu)
516{
517 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
518 bool bringup = st->bringup;
519 enum cpuhp_state state;
520
521 /*
522 * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures
523 * that if we see ->should_run we also see the rest of the state.
524 */
525 smp_mb();
526
527 if (WARN_ON_ONCE(!st->should_run))
528 return;
529
530 cpuhp_lock_acquire(bringup);
531
532 if (st->single) {
533 state = st->cb_state;
534 st->should_run = false;
535 } else {
536 if (bringup) {
537 st->state++;
538 state = st->state;
539 st->should_run = (st->state < st->target);
540 WARN_ON_ONCE(st->state > st->target);
541 } else {
542 state = st->state;
543 st->state--;
544 st->should_run = (st->state > st->target);
545 WARN_ON_ONCE(st->state < st->target);
546 }
547 }
548
549 WARN_ON_ONCE(!cpuhp_is_ap_state(state));
550
551 if (st->rollback) {
552 struct cpuhp_step *step = cpuhp_get_step(state);
553 if (step->skip_onerr)
554 goto next;
555 }
556
557 if (cpuhp_is_atomic_state(state)) {
558 local_irq_disable();
559 st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last);
560 local_irq_enable();
561
562 /*
563 * STARTING/DYING must not fail!
564 */
565 WARN_ON_ONCE(st->result);
566 } else {
567 st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last);
568 }
569
570 if (st->result) {
571 /*
572 * If we fail on a rollback, we're up a creek without no
573 * paddle, no way forward, no way back. We loose, thanks for
574 * playing.
575 */
576 WARN_ON_ONCE(st->rollback);
577 st->should_run = false;
578 }
579
580next:
581 cpuhp_lock_release(bringup);
582
583 if (!st->should_run)
584 complete_ap_thread(st, bringup);
585}
586
587/* Invoke a single callback on a remote cpu */
588static int
589cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup,
590 struct hlist_node *node)
591{
592 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
593 int ret;
594
595 if (!cpu_online(cpu))
596 return 0;
597
598 cpuhp_lock_acquire(false);
599 cpuhp_lock_release(false);
600
601 cpuhp_lock_acquire(true);
602 cpuhp_lock_release(true);
603
604 /*
605 * If we are up and running, use the hotplug thread. For early calls
606 * we invoke the thread function directly.
607 */
608 if (!st->thread)
609 return cpuhp_invoke_callback(cpu, state, bringup, node, NULL);
610
611 st->rollback = false;
612 st->last = NULL;
613
614 st->node = node;
615 st->bringup = bringup;
616 st->cb_state = state;
617 st->single = true;
618
619 __cpuhp_kick_ap(st);
620
621 /*
622 * If we failed and did a partial, do a rollback.
623 */
624 if ((ret = st->result) && st->last) {
625 st->rollback = true;
626 st->bringup = !bringup;
627
628 __cpuhp_kick_ap(st);
629 }
630
631 /*
632 * Clean up the leftovers so the next hotplug operation wont use stale
633 * data.
634 */
635 st->node = st->last = NULL;
636 return ret;
637}
638
639static int cpuhp_kick_ap_work(unsigned int cpu)
640{
641 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
642 enum cpuhp_state prev_state = st->state;
643 int ret;
644
645 cpuhp_lock_acquire(false);
646 cpuhp_lock_release(false);
647
648 cpuhp_lock_acquire(true);
649 cpuhp_lock_release(true);
650
651 trace_cpuhp_enter(cpu, st->target, prev_state, cpuhp_kick_ap_work);
652 ret = cpuhp_kick_ap(st, st->target);
653 trace_cpuhp_exit(cpu, st->state, prev_state, ret);
654
655 return ret;
656}
657
658static struct smp_hotplug_thread cpuhp_threads = {
659 .store = &cpuhp_state.thread,
660 .create = &cpuhp_create,
661 .thread_should_run = cpuhp_should_run,
662 .thread_fn = cpuhp_thread_fun,
663 .thread_comm = "cpuhp/%u",
664 .selfparking = true,
665};
666
667void __init cpuhp_threads_init(void)
668{
669 BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads));
670 kthread_unpark(this_cpu_read(cpuhp_state.thread));
671}
672
673#ifdef CONFIG_HOTPLUG_CPU
674/**
675 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
676 * @cpu: a CPU id
677 *
678 * This function walks all processes, finds a valid mm struct for each one and
679 * then clears a corresponding bit in mm's cpumask. While this all sounds
680 * trivial, there are various non-obvious corner cases, which this function
681 * tries to solve in a safe manner.
682 *
683 * Also note that the function uses a somewhat relaxed locking scheme, so it may
684 * be called only for an already offlined CPU.
685 */
686void clear_tasks_mm_cpumask(int cpu)
687{
688 struct task_struct *p;
689
690 /*
691 * This function is called after the cpu is taken down and marked
692 * offline, so its not like new tasks will ever get this cpu set in
693 * their mm mask. -- Peter Zijlstra
694 * Thus, we may use rcu_read_lock() here, instead of grabbing
695 * full-fledged tasklist_lock.
696 */
697 WARN_ON(cpu_online(cpu));
698 rcu_read_lock();
699 for_each_process(p) {
700 struct task_struct *t;
701
702 /*
703 * Main thread might exit, but other threads may still have
704 * a valid mm. Find one.
705 */
706 t = find_lock_task_mm(p);
707 if (!t)
708 continue;
709 cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
710 task_unlock(t);
711 }
712 rcu_read_unlock();
713}
714
715/* Take this CPU down. */
716static int take_cpu_down(void *_param)
717{
718 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
719 enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE);
720 int err, cpu = smp_processor_id();
721 int ret;
722
723 /* Ensure this CPU doesn't handle any more interrupts. */
724 err = __cpu_disable();
725 if (err < 0)
726 return err;
727
728 /*
729 * We get here while we are in CPUHP_TEARDOWN_CPU state and we must not
730 * do this step again.
731 */
732 WARN_ON(st->state != CPUHP_TEARDOWN_CPU);
733 st->state--;
734 /* Invoke the former CPU_DYING callbacks */
735 for (; st->state > target; st->state--) {
736 ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
737 /*
738 * DYING must not fail!
739 */
740 WARN_ON_ONCE(ret);
741 }
742
743 /* Give up timekeeping duties */
744 tick_handover_do_timer();
745 /* Park the stopper thread */
746 stop_machine_park(cpu);
747 return 0;
748}
749
750static int takedown_cpu(unsigned int cpu)
751{
752 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
753 int err;
754
755 /* Park the smpboot threads */
756 kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread);
757 smpboot_park_threads(cpu);
758
759 /*
760 * Prevent irq alloc/free while the dying cpu reorganizes the
761 * interrupt affinities.
762 */
763 irq_lock_sparse();
764
765 /*
766 * So now all preempt/rcu users must observe !cpu_active().
767 */
768 err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu));
769 if (err) {
770 /* CPU refused to die */
771 irq_unlock_sparse();
772 /* Unpark the hotplug thread so we can rollback there */
773 kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread);
774 return err;
775 }
776 BUG_ON(cpu_online(cpu));
777
778 /*
779 * The teardown callback for CPUHP_AP_SCHED_STARTING will have removed
780 * all runnable tasks from the CPU, there's only the idle task left now
781 * that the migration thread is done doing the stop_machine thing.
782 *
783 * Wait for the stop thread to go away.
784 */
785 wait_for_ap_thread(st, false);
786 BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
787
788 /* Interrupts are moved away from the dying cpu, reenable alloc/free */
789 irq_unlock_sparse();
790
791 hotplug_cpu__broadcast_tick_pull(cpu);
792 /* This actually kills the CPU. */
793 __cpu_die(cpu);
794
795 tick_cleanup_dead_cpu(cpu);
796 rcutree_migrate_callbacks(cpu);
797 return 0;
798}
799
800static void cpuhp_complete_idle_dead(void *arg)
801{
802 struct cpuhp_cpu_state *st = arg;
803
804 complete_ap_thread(st, false);
805}
806
807void cpuhp_report_idle_dead(void)
808{
809 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
810
811 BUG_ON(st->state != CPUHP_AP_OFFLINE);
812 rcu_report_dead(smp_processor_id());
813 st->state = CPUHP_AP_IDLE_DEAD;
814 /*
815 * We cannot call complete after rcu_report_dead() so we delegate it
816 * to an online cpu.
817 */
818 smp_call_function_single(cpumask_first(cpu_online_mask),
819 cpuhp_complete_idle_dead, st, 0);
820}
821
822static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st)
823{
824 for (st->state++; st->state < st->target; st->state++) {
825 struct cpuhp_step *step = cpuhp_get_step(st->state);
826
827 if (!step->skip_onerr)
828 cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
829 }
830}
831
832static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
833 enum cpuhp_state target)
834{
835 enum cpuhp_state prev_state = st->state;
836 int ret = 0;
837
838 for (; st->state > target; st->state--) {
839 ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
840 if (ret) {
841 st->target = prev_state;
842 undo_cpu_down(cpu, st);
843 break;
844 }
845 }
846 return ret;
847}
848
849/* Requires cpu_add_remove_lock to be held */
850static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
851 enum cpuhp_state target)
852{
853 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
854 int prev_state, ret = 0;
855
856 if (num_online_cpus() == 1)
857 return -EBUSY;
858
859 if (!cpu_present(cpu))
860 return -EINVAL;
861
862 cpus_write_lock();
863
864 cpuhp_tasks_frozen = tasks_frozen;
865
866 prev_state = cpuhp_set_state(st, target);
867 /*
868 * If the current CPU state is in the range of the AP hotplug thread,
869 * then we need to kick the thread.
870 */
871 if (st->state > CPUHP_TEARDOWN_CPU) {
872 st->target = max((int)target, CPUHP_TEARDOWN_CPU);
873 ret = cpuhp_kick_ap_work(cpu);
874 /*
875 * The AP side has done the error rollback already. Just
876 * return the error code..
877 */
878 if (ret)
879 goto out;
880
881 /*
882 * We might have stopped still in the range of the AP hotplug
883 * thread. Nothing to do anymore.
884 */
885 if (st->state > CPUHP_TEARDOWN_CPU)
886 goto out;
887
888 st->target = target;
889 }
890 /*
891 * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need
892 * to do the further cleanups.
893 */
894 ret = cpuhp_down_callbacks(cpu, st, target);
895 if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) {
896 cpuhp_reset_state(st, prev_state);
897 __cpuhp_kick_ap(st);
898 }
899
900out:
901 cpus_write_unlock();
902 /*
903 * Do post unplug cleanup. This is still protected against
904 * concurrent CPU hotplug via cpu_add_remove_lock.
905 */
906 lockup_detector_cleanup();
907 return ret;
908}
909
910static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
911{
912 int err;
913
914 cpu_maps_update_begin();
915
916 if (cpu_hotplug_disabled) {
917 err = -EBUSY;
918 goto out;
919 }
920
921 err = _cpu_down(cpu, 0, target);
922
923out:
924 cpu_maps_update_done();
925 return err;
926}
927
928int cpu_down(unsigned int cpu)
929{
930 return do_cpu_down(cpu, CPUHP_OFFLINE);
931}
932EXPORT_SYMBOL(cpu_down);
933
934#else
935#define takedown_cpu NULL
936#endif /*CONFIG_HOTPLUG_CPU*/
937
938/**
939 * notify_cpu_starting(cpu) - Invoke the callbacks on the starting CPU
940 * @cpu: cpu that just started
941 *
942 * It must be called by the arch code on the new cpu, before the new cpu
943 * enables interrupts and before the "boot" cpu returns from __cpu_up().
944 */
945void notify_cpu_starting(unsigned int cpu)
946{
947 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
948 enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
949 int ret;
950
951 rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */
952 while (st->state < target) {
953 st->state++;
954 ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
955 /*
956 * STARTING must not fail!
957 */
958 WARN_ON_ONCE(ret);
959 }
960}
961
962/*
963 * Called from the idle task. Wake up the controlling task which brings the
964 * stopper and the hotplug thread of the upcoming CPU up and then delegates
965 * the rest of the online bringup to the hotplug thread.
966 */
967void cpuhp_online_idle(enum cpuhp_state state)
968{
969 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
970
971 /* Happens for the boot cpu */
972 if (state != CPUHP_AP_ONLINE_IDLE)
973 return;
974
975 st->state = CPUHP_AP_ONLINE_IDLE;
976 complete_ap_thread(st, true);
977}
978
979/* Requires cpu_add_remove_lock to be held */
980static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
981{
982 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
983 struct task_struct *idle;
984 int ret = 0;
985
986 cpus_write_lock();
987
988 if (!cpu_present(cpu)) {
989 ret = -EINVAL;
990 goto out;
991 }
992
993 /*
994 * The caller of do_cpu_up might have raced with another
995 * caller. Ignore it for now.
996 */
997 if (st->state >= target)
998 goto out;
999
1000 if (st->state == CPUHP_OFFLINE) {
1001 /* Let it fail before we try to bring the cpu up */
1002 idle = idle_thread_get(cpu);
1003 if (IS_ERR(idle)) {
1004 ret = PTR_ERR(idle);
1005 goto out;
1006 }
1007 }
1008
1009 cpuhp_tasks_frozen = tasks_frozen;
1010
1011 cpuhp_set_state(st, target);
1012 /*
1013 * If the current CPU state is in the range of the AP hotplug thread,
1014 * then we need to kick the thread once more.
1015 */
1016 if (st->state > CPUHP_BRINGUP_CPU) {
1017 ret = cpuhp_kick_ap_work(cpu);
1018 /*
1019 * The AP side has done the error rollback already. Just
1020 * return the error code..
1021 */
1022 if (ret)
1023 goto out;
1024 }
1025
1026 /*
1027 * Try to reach the target state. We max out on the BP at
1028 * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
1029 * responsible for bringing it up to the target state.
1030 */
1031 target = min((int)target, CPUHP_BRINGUP_CPU);
1032 ret = cpuhp_up_callbacks(cpu, st, target);
1033out:
1034 cpus_write_unlock();
1035 return ret;
1036}
1037
1038static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
1039{
1040 int err = 0;
1041
1042 if (!cpu_possible(cpu)) {
1043 pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
1044 cpu);
1045#if defined(CONFIG_IA64)
1046 pr_err("please check additional_cpus= boot parameter\n");
1047#endif
1048 return -EINVAL;
1049 }
1050
1051 err = try_online_node(cpu_to_node(cpu));
1052 if (err)
1053 return err;
1054
1055 cpu_maps_update_begin();
1056
1057 if (cpu_hotplug_disabled) {
1058 err = -EBUSY;
1059 goto out;
1060 }
1061
1062 err = _cpu_up(cpu, 0, target);
1063out:
1064 cpu_maps_update_done();
1065 return err;
1066}
1067
1068int cpu_up(unsigned int cpu)
1069{
1070 return do_cpu_up(cpu, CPUHP_ONLINE);
1071}
1072EXPORT_SYMBOL_GPL(cpu_up);
1073
1074#ifdef CONFIG_PM_SLEEP_SMP
1075static cpumask_var_t frozen_cpus;
1076
1077int freeze_secondary_cpus(int primary)
1078{
1079 int cpu, error = 0;
1080
1081 cpu_maps_update_begin();
1082 if (!cpu_online(primary))
1083 primary = cpumask_first(cpu_online_mask);
1084 /*
1085 * We take down all of the non-boot CPUs in one shot to avoid races
1086 * with the userspace trying to use the CPU hotplug at the same time
1087 */
1088 cpumask_clear(frozen_cpus);
1089
1090 pr_info("Disabling non-boot CPUs ...\n");
1091 for_each_online_cpu(cpu) {
1092 if (cpu == primary)
1093 continue;
1094 trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
1095 error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
1096 trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
1097 if (!error)
1098 cpumask_set_cpu(cpu, frozen_cpus);
1099 else {
1100 pr_err("Error taking CPU%d down: %d\n", cpu, error);
1101 break;
1102 }
1103 }
1104
1105 if (!error)
1106 BUG_ON(num_online_cpus() > 1);
1107 else
1108 pr_err("Non-boot CPUs are not disabled\n");
1109
1110 /*
1111 * Make sure the CPUs won't be enabled by someone else. We need to do
1112 * this even in case of failure as all disable_nonboot_cpus() users are
1113 * supposed to do enable_nonboot_cpus() on the failure path.
1114 */
1115 cpu_hotplug_disabled++;
1116
1117 cpu_maps_update_done();
1118 return error;
1119}
1120
1121void __weak arch_enable_nonboot_cpus_begin(void)
1122{
1123}
1124
1125void __weak arch_enable_nonboot_cpus_end(void)
1126{
1127}
1128
1129void enable_nonboot_cpus(void)
1130{
1131 int cpu, error;
1132
1133 /* Allow everyone to use the CPU hotplug again */
1134 cpu_maps_update_begin();
1135 __cpu_hotplug_enable();
1136 if (cpumask_empty(frozen_cpus))
1137 goto out;
1138
1139 pr_info("Enabling non-boot CPUs ...\n");
1140
1141 arch_enable_nonboot_cpus_begin();
1142
1143 for_each_cpu(cpu, frozen_cpus) {
1144 trace_suspend_resume(TPS("CPU_ON"), cpu, true);
1145 error = _cpu_up(cpu, 1, CPUHP_ONLINE);
1146 trace_suspend_resume(TPS("CPU_ON"), cpu, false);
1147 if (!error) {
1148 pr_info("CPU%d is up\n", cpu);
1149 continue;
1150 }
1151 pr_warn("Error taking CPU%d up: %d\n", cpu, error);
1152 }
1153
1154 arch_enable_nonboot_cpus_end();
1155
1156 cpumask_clear(frozen_cpus);
1157out:
1158 cpu_maps_update_done();
1159}
1160
1161static int __init alloc_frozen_cpus(void)
1162{
1163 if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
1164 return -ENOMEM;
1165 return 0;
1166}
1167core_initcall(alloc_frozen_cpus);
1168
1169/*
1170 * When callbacks for CPU hotplug notifications are being executed, we must
1171 * ensure that the state of the system with respect to the tasks being frozen
1172 * or not, as reported by the notification, remains unchanged *throughout the
1173 * duration* of the execution of the callbacks.
1174 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
1175 *
1176 * This synchronization is implemented by mutually excluding regular CPU
1177 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
1178 * Hibernate notifications.
1179 */
1180static int
1181cpu_hotplug_pm_callback(struct notifier_block *nb,
1182 unsigned long action, void *ptr)
1183{
1184 switch (action) {
1185
1186 case PM_SUSPEND_PREPARE:
1187 case PM_HIBERNATION_PREPARE:
1188 cpu_hotplug_disable();
1189 break;
1190
1191 case PM_POST_SUSPEND:
1192 case PM_POST_HIBERNATION:
1193 cpu_hotplug_enable();
1194 break;
1195
1196 default:
1197 return NOTIFY_DONE;
1198 }
1199
1200 return NOTIFY_OK;
1201}
1202
1203
1204static int __init cpu_hotplug_pm_sync_init(void)
1205{
1206 /*
1207 * cpu_hotplug_pm_callback has higher priority than x86
1208 * bsp_pm_callback which depends on cpu_hotplug_pm_callback
1209 * to disable cpu hotplug to avoid cpu hotplug race.
1210 */
1211 pm_notifier(cpu_hotplug_pm_callback, 0);
1212 return 0;
1213}
1214core_initcall(cpu_hotplug_pm_sync_init);
1215
1216#endif /* CONFIG_PM_SLEEP_SMP */
1217
1218int __boot_cpu_id;
1219
1220#endif /* CONFIG_SMP */
1221
1222/* Boot processor state steps */
1223static struct cpuhp_step cpuhp_hp_states[] = {
1224 [CPUHP_OFFLINE] = {
1225 .name = "offline",
1226 .startup.single = NULL,
1227 .teardown.single = NULL,
1228 },
1229#ifdef CONFIG_SMP
1230 [CPUHP_CREATE_THREADS]= {
1231 .name = "threads:prepare",
1232 .startup.single = smpboot_create_threads,
1233 .teardown.single = NULL,
1234 .cant_stop = true,
1235 },
1236 [CPUHP_PERF_PREPARE] = {
1237 .name = "perf:prepare",
1238 .startup.single = perf_event_init_cpu,
1239 .teardown.single = perf_event_exit_cpu,
1240 },
1241 [CPUHP_WORKQUEUE_PREP] = {
1242 .name = "workqueue:prepare",
1243 .startup.single = workqueue_prepare_cpu,
1244 .teardown.single = NULL,
1245 },
1246 [CPUHP_HRTIMERS_PREPARE] = {
1247 .name = "hrtimers:prepare",
1248 .startup.single = hrtimers_prepare_cpu,
1249 .teardown.single = hrtimers_dead_cpu,
1250 },
1251 [CPUHP_SMPCFD_PREPARE] = {
1252 .name = "smpcfd:prepare",
1253 .startup.single = smpcfd_prepare_cpu,
1254 .teardown.single = smpcfd_dead_cpu,
1255 },
1256 [CPUHP_RELAY_PREPARE] = {
1257 .name = "relay:prepare",
1258 .startup.single = relay_prepare_cpu,
1259 .teardown.single = NULL,
1260 },
1261 [CPUHP_SLAB_PREPARE] = {
1262 .name = "slab:prepare",
1263 .startup.single = slab_prepare_cpu,
1264 .teardown.single = slab_dead_cpu,
1265 },
1266 [CPUHP_RCUTREE_PREP] = {
1267 .name = "RCU/tree:prepare",
1268 .startup.single = rcutree_prepare_cpu,
1269 .teardown.single = rcutree_dead_cpu,
1270 },
1271 /*
1272 * On the tear-down path, timers_dead_cpu() must be invoked
1273 * before blk_mq_queue_reinit_notify() from notify_dead(),
1274 * otherwise a RCU stall occurs.
1275 */
1276 [CPUHP_TIMERS_PREPARE] = {
1277 .name = "timers:dead",
1278 .startup.single = timers_prepare_cpu,
1279 .teardown.single = timers_dead_cpu,
1280 },
1281 /* Kicks the plugged cpu into life */
1282 [CPUHP_BRINGUP_CPU] = {
1283 .name = "cpu:bringup",
1284 .startup.single = bringup_cpu,
1285 .teardown.single = NULL,
1286 .cant_stop = true,
1287 },
1288 /* Final state before CPU kills itself */
1289 [CPUHP_AP_IDLE_DEAD] = {
1290 .name = "idle:dead",
1291 },
1292 /*
1293 * Last state before CPU enters the idle loop to die. Transient state
1294 * for synchronization.
1295 */
1296 [CPUHP_AP_OFFLINE] = {
1297 .name = "ap:offline",
1298 .cant_stop = true,
1299 },
1300 /* First state is scheduler control. Interrupts are disabled */
1301 [CPUHP_AP_SCHED_STARTING] = {
1302 .name = "sched:starting",
1303 .startup.single = sched_cpu_starting,
1304 .teardown.single = sched_cpu_dying,
1305 },
1306 [CPUHP_AP_RCUTREE_DYING] = {
1307 .name = "RCU/tree:dying",
1308 .startup.single = NULL,
1309 .teardown.single = rcutree_dying_cpu,
1310 },
1311 [CPUHP_AP_SMPCFD_DYING] = {
1312 .name = "smpcfd:dying",
1313 .startup.single = NULL,
1314 .teardown.single = smpcfd_dying_cpu,
1315 },
1316 /* Entry state on starting. Interrupts enabled from here on. Transient
1317 * state for synchronsization */
1318 [CPUHP_AP_ONLINE] = {
1319 .name = "ap:online",
1320 },
1321 /*
1322 * Handled on controll processor until the plugged processor manages
1323 * this itself.
1324 */
1325 [CPUHP_TEARDOWN_CPU] = {
1326 .name = "cpu:teardown",
1327 .startup.single = NULL,
1328 .teardown.single = takedown_cpu,
1329 .cant_stop = true,
1330 },
1331 /* Handle smpboot threads park/unpark */
1332 [CPUHP_AP_SMPBOOT_THREADS] = {
1333 .name = "smpboot/threads:online",
1334 .startup.single = smpboot_unpark_threads,
1335 .teardown.single = NULL,
1336 },
1337 [CPUHP_AP_IRQ_AFFINITY_ONLINE] = {
1338 .name = "irq/affinity:online",
1339 .startup.single = irq_affinity_online_cpu,
1340 .teardown.single = NULL,
1341 },
1342 [CPUHP_AP_PERF_ONLINE] = {
1343 .name = "perf:online",
1344 .startup.single = perf_event_init_cpu,
1345 .teardown.single = perf_event_exit_cpu,
1346 },
1347 [CPUHP_AP_WORKQUEUE_ONLINE] = {
1348 .name = "workqueue:online",
1349 .startup.single = workqueue_online_cpu,
1350 .teardown.single = workqueue_offline_cpu,
1351 },
1352 [CPUHP_AP_RCUTREE_ONLINE] = {
1353 .name = "RCU/tree:online",
1354 .startup.single = rcutree_online_cpu,
1355 .teardown.single = rcutree_offline_cpu,
1356 },
1357#endif
1358 /*
1359 * The dynamically registered state space is here
1360 */
1361
1362#ifdef CONFIG_SMP
1363 /* Last state is scheduler control setting the cpu active */
1364 [CPUHP_AP_ACTIVE] = {
1365 .name = "sched:active",
1366 .startup.single = sched_cpu_activate,
1367 .teardown.single = sched_cpu_deactivate,
1368 },
1369#endif
1370
1371 /* CPU is fully up and running. */
1372 [CPUHP_ONLINE] = {
1373 .name = "online",
1374 .startup.single = NULL,
1375 .teardown.single = NULL,
1376 },
1377};
1378
1379/* Sanity check for callbacks */
1380static int cpuhp_cb_check(enum cpuhp_state state)
1381{
1382 if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
1383 return -EINVAL;
1384 return 0;
1385}
1386
1387/*
1388 * Returns a free for dynamic slot assignment of the Online state. The states
1389 * are protected by the cpuhp_slot_states mutex and an empty slot is identified
1390 * by having no name assigned.
1391 */
1392static int cpuhp_reserve_state(enum cpuhp_state state)
1393{
1394 enum cpuhp_state i, end;
1395 struct cpuhp_step *step;
1396
1397 switch (state) {
1398 case CPUHP_AP_ONLINE_DYN:
1399 step = cpuhp_hp_states + CPUHP_AP_ONLINE_DYN;
1400 end = CPUHP_AP_ONLINE_DYN_END;
1401 break;
1402 case CPUHP_BP_PREPARE_DYN:
1403 step = cpuhp_hp_states + CPUHP_BP_PREPARE_DYN;
1404 end = CPUHP_BP_PREPARE_DYN_END;
1405 break;
1406 default:
1407 return -EINVAL;
1408 }
1409
1410 for (i = state; i <= end; i++, step++) {
1411 if (!step->name)
1412 return i;
1413 }
1414 WARN(1, "No more dynamic states available for CPU hotplug\n");
1415 return -ENOSPC;
1416}
1417
1418static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name,
1419 int (*startup)(unsigned int cpu),
1420 int (*teardown)(unsigned int cpu),
1421 bool multi_instance)
1422{
1423 /* (Un)Install the callbacks for further cpu hotplug operations */
1424 struct cpuhp_step *sp;
1425 int ret = 0;
1426
1427 /*
1428 * If name is NULL, then the state gets removed.
1429 *
1430 * CPUHP_AP_ONLINE_DYN and CPUHP_BP_PREPARE_DYN are handed out on
1431 * the first allocation from these dynamic ranges, so the removal
1432 * would trigger a new allocation and clear the wrong (already
1433 * empty) state, leaving the callbacks of the to be cleared state
1434 * dangling, which causes wreckage on the next hotplug operation.
1435 */
1436 if (name && (state == CPUHP_AP_ONLINE_DYN ||
1437 state == CPUHP_BP_PREPARE_DYN)) {
1438 ret = cpuhp_reserve_state(state);
1439 if (ret < 0)
1440 return ret;
1441 state = ret;
1442 }
1443 sp = cpuhp_get_step(state);
1444 if (name && sp->name)
1445 return -EBUSY;
1446
1447 sp->startup.single = startup;
1448 sp->teardown.single = teardown;
1449 sp->name = name;
1450 sp->multi_instance = multi_instance;
1451 INIT_HLIST_HEAD(&sp->list);
1452 return ret;
1453}
1454
1455static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
1456{
1457 return cpuhp_get_step(state)->teardown.single;
1458}
1459
1460/*
1461 * Call the startup/teardown function for a step either on the AP or
1462 * on the current CPU.
1463 */
1464static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup,
1465 struct hlist_node *node)
1466{
1467 struct cpuhp_step *sp = cpuhp_get_step(state);
1468 int ret;
1469
1470 /*
1471 * If there's nothing to do, we done.
1472 * Relies on the union for multi_instance.
1473 */
1474 if ((bringup && !sp->startup.single) ||
1475 (!bringup && !sp->teardown.single))
1476 return 0;
1477 /*
1478 * The non AP bound callbacks can fail on bringup. On teardown
1479 * e.g. module removal we crash for now.
1480 */
1481#ifdef CONFIG_SMP
1482 if (cpuhp_is_ap_state(state))
1483 ret = cpuhp_invoke_ap_callback(cpu, state, bringup, node);
1484 else
1485 ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL);
1486#else
1487 ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL);
1488#endif
1489 BUG_ON(ret && !bringup);
1490 return ret;
1491}
1492
1493/*
1494 * Called from __cpuhp_setup_state on a recoverable failure.
1495 *
1496 * Note: The teardown callbacks for rollback are not allowed to fail!
1497 */
1498static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
1499 struct hlist_node *node)
1500{
1501 int cpu;
1502
1503 /* Roll back the already executed steps on the other cpus */
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 (cpu >= failedcpu)
1509 break;
1510
1511 /* Did we invoke the startup call on that cpu ? */
1512 if (cpustate >= state)
1513 cpuhp_issue_call(cpu, state, false, node);
1514 }
1515}
1516
1517int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state,
1518 struct hlist_node *node,
1519 bool invoke)
1520{
1521 struct cpuhp_step *sp;
1522 int cpu;
1523 int ret;
1524
1525 lockdep_assert_cpus_held();
1526
1527 sp = cpuhp_get_step(state);
1528 if (sp->multi_instance == false)
1529 return -EINVAL;
1530
1531 mutex_lock(&cpuhp_state_mutex);
1532
1533 if (!invoke || !sp->startup.multi)
1534 goto add_node;
1535
1536 /*
1537 * Try to call the startup callback for each present cpu
1538 * depending on the hotplug state of the cpu.
1539 */
1540 for_each_present_cpu(cpu) {
1541 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1542 int cpustate = st->state;
1543
1544 if (cpustate < state)
1545 continue;
1546
1547 ret = cpuhp_issue_call(cpu, state, true, node);
1548 if (ret) {
1549 if (sp->teardown.multi)
1550 cpuhp_rollback_install(cpu, state, node);
1551 goto unlock;
1552 }
1553 }
1554add_node:
1555 ret = 0;
1556 hlist_add_head(node, &sp->list);
1557unlock:
1558 mutex_unlock(&cpuhp_state_mutex);
1559 return ret;
1560}
1561
1562int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
1563 bool invoke)
1564{
1565 int ret;
1566
1567 cpus_read_lock();
1568 ret = __cpuhp_state_add_instance_cpuslocked(state, node, invoke);
1569 cpus_read_unlock();
1570 return ret;
1571}
1572EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
1573
1574/**
1575 * __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state
1576 * @state: The state to setup
1577 * @invoke: If true, the startup function is invoked for cpus where
1578 * cpu state >= @state
1579 * @startup: startup callback function
1580 * @teardown: teardown callback function
1581 * @multi_instance: State is set up for multiple instances which get
1582 * added afterwards.
1583 *
1584 * The caller needs to hold cpus read locked while calling this function.
1585 * Returns:
1586 * On success:
1587 * Positive state number if @state is CPUHP_AP_ONLINE_DYN
1588 * 0 for all other states
1589 * On failure: proper (negative) error code
1590 */
1591int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state,
1592 const char *name, bool invoke,
1593 int (*startup)(unsigned int cpu),
1594 int (*teardown)(unsigned int cpu),
1595 bool multi_instance)
1596{
1597 int cpu, ret = 0;
1598 bool dynstate;
1599
1600 lockdep_assert_cpus_held();
1601
1602 if (cpuhp_cb_check(state) || !name)
1603 return -EINVAL;
1604
1605 mutex_lock(&cpuhp_state_mutex);
1606
1607 ret = cpuhp_store_callbacks(state, name, startup, teardown,
1608 multi_instance);
1609
1610 dynstate = state == CPUHP_AP_ONLINE_DYN;
1611 if (ret > 0 && dynstate) {
1612 state = ret;
1613 ret = 0;
1614 }
1615
1616 if (ret || !invoke || !startup)
1617 goto out;
1618
1619 /*
1620 * Try to call the startup callback for each present cpu
1621 * depending on the hotplug state of the cpu.
1622 */
1623 for_each_present_cpu(cpu) {
1624 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1625 int cpustate = st->state;
1626
1627 if (cpustate < state)
1628 continue;
1629
1630 ret = cpuhp_issue_call(cpu, state, true, NULL);
1631 if (ret) {
1632 if (teardown)
1633 cpuhp_rollback_install(cpu, state, NULL);
1634 cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
1635 goto out;
1636 }
1637 }
1638out:
1639 mutex_unlock(&cpuhp_state_mutex);
1640 /*
1641 * If the requested state is CPUHP_AP_ONLINE_DYN, return the
1642 * dynamically allocated state in case of success.
1643 */
1644 if (!ret && dynstate)
1645 return state;
1646 return ret;
1647}
1648EXPORT_SYMBOL(__cpuhp_setup_state_cpuslocked);
1649
1650int __cpuhp_setup_state(enum cpuhp_state state,
1651 const char *name, bool invoke,
1652 int (*startup)(unsigned int cpu),
1653 int (*teardown)(unsigned int cpu),
1654 bool multi_instance)
1655{
1656 int ret;
1657
1658 cpus_read_lock();
1659 ret = __cpuhp_setup_state_cpuslocked(state, name, invoke, startup,
1660 teardown, multi_instance);
1661 cpus_read_unlock();
1662 return ret;
1663}
1664EXPORT_SYMBOL(__cpuhp_setup_state);
1665
1666int __cpuhp_state_remove_instance(enum cpuhp_state state,
1667 struct hlist_node *node, bool invoke)
1668{
1669 struct cpuhp_step *sp = cpuhp_get_step(state);
1670 int cpu;
1671
1672 BUG_ON(cpuhp_cb_check(state));
1673
1674 if (!sp->multi_instance)
1675 return -EINVAL;
1676
1677 cpus_read_lock();
1678 mutex_lock(&cpuhp_state_mutex);
1679
1680 if (!invoke || !cpuhp_get_teardown_cb(state))
1681 goto remove;
1682 /*
1683 * Call the teardown callback for each present cpu depending
1684 * on the hotplug state of the cpu. This function is not
1685 * allowed to fail currently!
1686 */
1687 for_each_present_cpu(cpu) {
1688 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1689 int cpustate = st->state;
1690
1691 if (cpustate >= state)
1692 cpuhp_issue_call(cpu, state, false, node);
1693 }
1694
1695remove:
1696 hlist_del(node);
1697 mutex_unlock(&cpuhp_state_mutex);
1698 cpus_read_unlock();
1699
1700 return 0;
1701}
1702EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance);
1703
1704/**
1705 * __cpuhp_remove_state_cpuslocked - Remove the callbacks for an hotplug machine state
1706 * @state: The state to remove
1707 * @invoke: If true, the teardown function is invoked for cpus where
1708 * cpu state >= @state
1709 *
1710 * The caller needs to hold cpus read locked while calling this function.
1711 * The teardown callback is currently not allowed to fail. Think
1712 * about module removal!
1713 */
1714void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke)
1715{
1716 struct cpuhp_step *sp = cpuhp_get_step(state);
1717 int cpu;
1718
1719 BUG_ON(cpuhp_cb_check(state));
1720
1721 lockdep_assert_cpus_held();
1722
1723 mutex_lock(&cpuhp_state_mutex);
1724 if (sp->multi_instance) {
1725 WARN(!hlist_empty(&sp->list),
1726 "Error: Removing state %d which has instances left.\n",
1727 state);
1728 goto remove;
1729 }
1730
1731 if (!invoke || !cpuhp_get_teardown_cb(state))
1732 goto remove;
1733
1734 /*
1735 * Call the teardown callback for each present cpu depending
1736 * on the hotplug state of the cpu. This function is not
1737 * allowed to fail currently!
1738 */
1739 for_each_present_cpu(cpu) {
1740 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1741 int cpustate = st->state;
1742
1743 if (cpustate >= state)
1744 cpuhp_issue_call(cpu, state, false, NULL);
1745 }
1746remove:
1747 cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
1748 mutex_unlock(&cpuhp_state_mutex);
1749}
1750EXPORT_SYMBOL(__cpuhp_remove_state_cpuslocked);
1751
1752void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
1753{
1754 cpus_read_lock();
1755 __cpuhp_remove_state_cpuslocked(state, invoke);
1756 cpus_read_unlock();
1757}
1758EXPORT_SYMBOL(__cpuhp_remove_state);
1759
1760#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
1761static ssize_t show_cpuhp_state(struct device *dev,
1762 struct device_attribute *attr, char *buf)
1763{
1764 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1765
1766 return sprintf(buf, "%d\n", st->state);
1767}
1768static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
1769
1770static ssize_t write_cpuhp_target(struct device *dev,
1771 struct device_attribute *attr,
1772 const char *buf, size_t count)
1773{
1774 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1775 struct cpuhp_step *sp;
1776 int target, ret;
1777
1778 ret = kstrtoint(buf, 10, &target);
1779 if (ret)
1780 return ret;
1781
1782#ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
1783 if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
1784 return -EINVAL;
1785#else
1786 if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
1787 return -EINVAL;
1788#endif
1789
1790 ret = lock_device_hotplug_sysfs();
1791 if (ret)
1792 return ret;
1793
1794 mutex_lock(&cpuhp_state_mutex);
1795 sp = cpuhp_get_step(target);
1796 ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
1797 mutex_unlock(&cpuhp_state_mutex);
1798 if (ret)
1799 goto out;
1800
1801 if (st->state < target)
1802 ret = do_cpu_up(dev->id, target);
1803 else
1804 ret = do_cpu_down(dev->id, target);
1805out:
1806 unlock_device_hotplug();
1807 return ret ? ret : count;
1808}
1809
1810static ssize_t show_cpuhp_target(struct device *dev,
1811 struct device_attribute *attr, char *buf)
1812{
1813 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1814
1815 return sprintf(buf, "%d\n", st->target);
1816}
1817static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
1818
1819
1820static ssize_t write_cpuhp_fail(struct device *dev,
1821 struct device_attribute *attr,
1822 const char *buf, size_t count)
1823{
1824 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1825 struct cpuhp_step *sp;
1826 int fail, ret;
1827
1828 ret = kstrtoint(buf, 10, &fail);
1829 if (ret)
1830 return ret;
1831
1832 /*
1833 * Cannot fail STARTING/DYING callbacks.
1834 */
1835 if (cpuhp_is_atomic_state(fail))
1836 return -EINVAL;
1837
1838 /*
1839 * Cannot fail anything that doesn't have callbacks.
1840 */
1841 mutex_lock(&cpuhp_state_mutex);
1842 sp = cpuhp_get_step(fail);
1843 if (!sp->startup.single && !sp->teardown.single)
1844 ret = -EINVAL;
1845 mutex_unlock(&cpuhp_state_mutex);
1846 if (ret)
1847 return ret;
1848
1849 st->fail = fail;
1850
1851 return count;
1852}
1853
1854static ssize_t show_cpuhp_fail(struct device *dev,
1855 struct device_attribute *attr, char *buf)
1856{
1857 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1858
1859 return sprintf(buf, "%d\n", st->fail);
1860}
1861
1862static DEVICE_ATTR(fail, 0644, show_cpuhp_fail, write_cpuhp_fail);
1863
1864static struct attribute *cpuhp_cpu_attrs[] = {
1865 &dev_attr_state.attr,
1866 &dev_attr_target.attr,
1867 &dev_attr_fail.attr,
1868 NULL
1869};
1870
1871static const struct attribute_group cpuhp_cpu_attr_group = {
1872 .attrs = cpuhp_cpu_attrs,
1873 .name = "hotplug",
1874 NULL
1875};
1876
1877static ssize_t show_cpuhp_states(struct device *dev,
1878 struct device_attribute *attr, char *buf)
1879{
1880 ssize_t cur, res = 0;
1881 int i;
1882
1883 mutex_lock(&cpuhp_state_mutex);
1884 for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
1885 struct cpuhp_step *sp = cpuhp_get_step(i);
1886
1887 if (sp->name) {
1888 cur = sprintf(buf, "%3d: %s\n", i, sp->name);
1889 buf += cur;
1890 res += cur;
1891 }
1892 }
1893 mutex_unlock(&cpuhp_state_mutex);
1894 return res;
1895}
1896static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);
1897
1898static struct attribute *cpuhp_cpu_root_attrs[] = {
1899 &dev_attr_states.attr,
1900 NULL
1901};
1902
1903static const struct attribute_group cpuhp_cpu_root_attr_group = {
1904 .attrs = cpuhp_cpu_root_attrs,
1905 .name = "hotplug",
1906 NULL
1907};
1908
1909static int __init cpuhp_sysfs_init(void)
1910{
1911 int cpu, ret;
1912
1913 ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
1914 &cpuhp_cpu_root_attr_group);
1915 if (ret)
1916 return ret;
1917
1918 for_each_possible_cpu(cpu) {
1919 struct device *dev = get_cpu_device(cpu);
1920
1921 if (!dev)
1922 continue;
1923 ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);
1924 if (ret)
1925 return ret;
1926 }
1927 return 0;
1928}
1929device_initcall(cpuhp_sysfs_init);
1930#endif
1931
1932/*
1933 * cpu_bit_bitmap[] is a special, "compressed" data structure that
1934 * represents all NR_CPUS bits binary values of 1<<nr.
1935 *
1936 * It is used by cpumask_of() to get a constant address to a CPU
1937 * mask value that has a single bit set only.
1938 */
1939
1940/* cpu_bit_bitmap[0] is empty - so we can back into it */
1941#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
1942#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
1943#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
1944#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
1945
1946const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
1947
1948 MASK_DECLARE_8(0), MASK_DECLARE_8(8),
1949 MASK_DECLARE_8(16), MASK_DECLARE_8(24),
1950#if BITS_PER_LONG > 32
1951 MASK_DECLARE_8(32), MASK_DECLARE_8(40),
1952 MASK_DECLARE_8(48), MASK_DECLARE_8(56),
1953#endif
1954};
1955EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
1956
1957const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
1958EXPORT_SYMBOL(cpu_all_bits);
1959
1960#ifdef CONFIG_INIT_ALL_POSSIBLE
1961struct cpumask __cpu_possible_mask __read_mostly
1962 = {CPU_BITS_ALL};
1963#else
1964struct cpumask __cpu_possible_mask __read_mostly;
1965#endif
1966EXPORT_SYMBOL(__cpu_possible_mask);
1967
1968struct cpumask __cpu_online_mask __read_mostly;
1969EXPORT_SYMBOL(__cpu_online_mask);
1970
1971struct cpumask __cpu_present_mask __read_mostly;
1972EXPORT_SYMBOL(__cpu_present_mask);
1973
1974struct cpumask __cpu_active_mask __read_mostly;
1975EXPORT_SYMBOL(__cpu_active_mask);
1976
1977void init_cpu_present(const struct cpumask *src)
1978{
1979 cpumask_copy(&__cpu_present_mask, src);
1980}
1981
1982void init_cpu_possible(const struct cpumask *src)
1983{
1984 cpumask_copy(&__cpu_possible_mask, src);
1985}
1986
1987void init_cpu_online(const struct cpumask *src)
1988{
1989 cpumask_copy(&__cpu_online_mask, src);
1990}
1991
1992/*
1993 * Activate the first processor.
1994 */
1995void __init boot_cpu_init(void)
1996{
1997 int cpu = smp_processor_id();
1998
1999 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
2000 set_cpu_online(cpu, true);
2001 set_cpu_active(cpu, true);
2002 set_cpu_present(cpu, true);
2003 set_cpu_possible(cpu, true);
2004
2005#ifdef CONFIG_SMP
2006 __boot_cpu_id = cpu;
2007#endif
2008}
2009
2010/*
2011 * Must be called _AFTER_ setting up the per_cpu areas
2012 */
2013void __init boot_cpu_state_init(void)
2014{
2015 per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
2016}