projects/linux·blob v4.9-rc5 · refs

1934 lines · 46.9 KiB

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#include <linux/relay.h>
27#include <linux/slab.h>
28
29#include <trace/events/power.h>
30#define CREATE_TRACE_POINTS
31#include <trace/events/cpuhp.h>
32
33#include "smpboot.h"
34
35/**
36 * cpuhp_cpu_state - Per cpu hotplug state storage
37 * @state: The current cpu state
38 * @target: The target state
39 * @thread: Pointer to the hotplug thread
40 * @should_run: Thread should execute
41 * @rollback: Perform a rollback
42 * @single: Single callback invocation
43 * @bringup: Single callback bringup or teardown selector
44 * @cb_state: The state for a single callback (install/uninstall)
45 * @result: Result of the operation
46 * @done: Signal completion to the issuer of the task
47 */
48struct cpuhp_cpu_state {
49 enum cpuhp_state state;
50 enum cpuhp_state target;
51#ifdef CONFIG_SMP
52 struct task_struct *thread;
53 bool should_run;
54 bool rollback;
55 bool single;
56 bool bringup;
57 struct hlist_node *node;
58 enum cpuhp_state cb_state;
59 int result;
60 struct completion done;
61#endif
62};
63
64static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state);
65
66/**
67 * cpuhp_step - Hotplug state machine step
68 * @name: Name of the step
69 * @startup: Startup function of the step
70 * @teardown: Teardown function of the step
71 * @skip_onerr: Do not invoke the functions on error rollback
72 * Will go away once the notifiers are gone
73 * @cant_stop: Bringup/teardown can't be stopped at this step
74 */
75struct cpuhp_step {
76 const char *name;
77 union {
78 int (*single)(unsigned int cpu);
79 int (*multi)(unsigned int cpu,
80 struct hlist_node *node);
81 } startup;
82 union {
83 int (*single)(unsigned int cpu);
84 int (*multi)(unsigned int cpu,
85 struct hlist_node *node);
86 } teardown;
87 struct hlist_head list;
88 bool skip_onerr;
89 bool cant_stop;
90 bool multi_instance;
91};
92
93static DEFINE_MUTEX(cpuhp_state_mutex);
94static struct cpuhp_step cpuhp_bp_states[];
95static struct cpuhp_step cpuhp_ap_states[];
96
97static bool cpuhp_is_ap_state(enum cpuhp_state state)
98{
99 /*
100 * The extra check for CPUHP_TEARDOWN_CPU is only for documentation
101 * purposes as that state is handled explicitly in cpu_down.
102 */
103 return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
104}
105
106static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
107{
108 struct cpuhp_step *sp;
109
110 sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states;
111 return sp + state;
112}
113
114/**
115 * cpuhp_invoke_callback _ Invoke the callbacks for a given state
116 * @cpu: The cpu for which the callback should be invoked
117 * @step: The step in the state machine
118 * @bringup: True if the bringup callback should be invoked
119 *
120 * Called from cpu hotplug and from the state register machinery.
121 */
122static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
123 bool bringup, struct hlist_node *node)
124{
125 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
126 struct cpuhp_step *step = cpuhp_get_step(state);
127 int (*cbm)(unsigned int cpu, struct hlist_node *node);
128 int (*cb)(unsigned int cpu);
129 int ret, cnt;
130
131 if (!step->multi_instance) {
132 cb = bringup ? step->startup.single : step->teardown.single;
133 if (!cb)
134 return 0;
135 trace_cpuhp_enter(cpu, st->target, state, cb);
136 ret = cb(cpu);
137 trace_cpuhp_exit(cpu, st->state, state, ret);
138 return ret;
139 }
140 cbm = bringup ? step->startup.multi : step->teardown.multi;
141 if (!cbm)
142 return 0;
143
144 /* Single invocation for instance add/remove */
145 if (node) {
146 trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
147 ret = cbm(cpu, node);
148 trace_cpuhp_exit(cpu, st->state, state, ret);
149 return ret;
150 }
151
152 /* State transition. Invoke on all instances */
153 cnt = 0;
154 hlist_for_each(node, &step->list) {
155 trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
156 ret = cbm(cpu, node);
157 trace_cpuhp_exit(cpu, st->state, state, ret);
158 if (ret)
159 goto err;
160 cnt++;
161 }
162 return 0;
163err:
164 /* Rollback the instances if one failed */
165 cbm = !bringup ? step->startup.multi : step->teardown.multi;
166 if (!cbm)
167 return ret;
168
169 hlist_for_each(node, &step->list) {
170 if (!cnt--)
171 break;
172 cbm(cpu, node);
173 }
174 return ret;
175}
176
177#ifdef CONFIG_SMP
178/* Serializes the updates to cpu_online_mask, cpu_present_mask */
179static DEFINE_MUTEX(cpu_add_remove_lock);
180bool cpuhp_tasks_frozen;
181EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen);
182
183/*
184 * The following two APIs (cpu_maps_update_begin/done) must be used when
185 * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
186 * The APIs cpu_notifier_register_begin/done() must be used to protect CPU
187 * hotplug callback (un)registration performed using __register_cpu_notifier()
188 * or __unregister_cpu_notifier().
189 */
190void cpu_maps_update_begin(void)
191{
192 mutex_lock(&cpu_add_remove_lock);
193}
194EXPORT_SYMBOL(cpu_notifier_register_begin);
195
196void cpu_maps_update_done(void)
197{
198 mutex_unlock(&cpu_add_remove_lock);
199}
200EXPORT_SYMBOL(cpu_notifier_register_done);
201
202static RAW_NOTIFIER_HEAD(cpu_chain);
203
204/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
205 * Should always be manipulated under cpu_add_remove_lock
206 */
207static int cpu_hotplug_disabled;
208
209#ifdef CONFIG_HOTPLUG_CPU
210
211static struct {
212 struct task_struct *active_writer;
213 /* wait queue to wake up the active_writer */
214 wait_queue_head_t wq;
215 /* verifies that no writer will get active while readers are active */
216 struct mutex lock;
217 /*
218 * Also blocks the new readers during
219 * an ongoing cpu hotplug operation.
220 */
221 atomic_t refcount;
222
223#ifdef CONFIG_DEBUG_LOCK_ALLOC
224 struct lockdep_map dep_map;
225#endif
226} cpu_hotplug = {
227 .active_writer = NULL,
228 .wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq),
229 .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
230#ifdef CONFIG_DEBUG_LOCK_ALLOC
231 .dep_map = STATIC_LOCKDEP_MAP_INIT("cpu_hotplug.dep_map", &cpu_hotplug.dep_map),
232#endif
233};
234
235/* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
236#define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
237#define cpuhp_lock_acquire_tryread() \
238 lock_map_acquire_tryread(&cpu_hotplug.dep_map)
239#define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map)
240#define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map)
241
242
243void get_online_cpus(void)
244{
245 might_sleep();
246 if (cpu_hotplug.active_writer == current)
247 return;
248 cpuhp_lock_acquire_read();
249 mutex_lock(&cpu_hotplug.lock);
250 atomic_inc(&cpu_hotplug.refcount);
251 mutex_unlock(&cpu_hotplug.lock);
252}
253EXPORT_SYMBOL_GPL(get_online_cpus);
254
255void put_online_cpus(void)
256{
257 int refcount;
258
259 if (cpu_hotplug.active_writer == current)
260 return;
261
262 refcount = atomic_dec_return(&cpu_hotplug.refcount);
263 if (WARN_ON(refcount < 0)) /* try to fix things up */
264 atomic_inc(&cpu_hotplug.refcount);
265
266 if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq))
267 wake_up(&cpu_hotplug.wq);
268
269 cpuhp_lock_release();
270
271}
272EXPORT_SYMBOL_GPL(put_online_cpus);
273
274/*
275 * This ensures that the hotplug operation can begin only when the
276 * refcount goes to zero.
277 *
278 * Note that during a cpu-hotplug operation, the new readers, if any,
279 * will be blocked by the cpu_hotplug.lock
280 *
281 * Since cpu_hotplug_begin() is always called after invoking
282 * cpu_maps_update_begin(), we can be sure that only one writer is active.
283 *
284 * Note that theoretically, there is a possibility of a livelock:
285 * - Refcount goes to zero, last reader wakes up the sleeping
286 * writer.
287 * - Last reader unlocks the cpu_hotplug.lock.
288 * - A new reader arrives at this moment, bumps up the refcount.
289 * - The writer acquires the cpu_hotplug.lock finds the refcount
290 * non zero and goes to sleep again.
291 *
292 * However, this is very difficult to achieve in practice since
293 * get_online_cpus() not an api which is called all that often.
294 *
295 */
296void cpu_hotplug_begin(void)
297{
298 DEFINE_WAIT(wait);
299
300 cpu_hotplug.active_writer = current;
301 cpuhp_lock_acquire();
302
303 for (;;) {
304 mutex_lock(&cpu_hotplug.lock);
305 prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE);
306 if (likely(!atomic_read(&cpu_hotplug.refcount)))
307 break;
308 mutex_unlock(&cpu_hotplug.lock);
309 schedule();
310 }
311 finish_wait(&cpu_hotplug.wq, &wait);
312}
313
314void cpu_hotplug_done(void)
315{
316 cpu_hotplug.active_writer = NULL;
317 mutex_unlock(&cpu_hotplug.lock);
318 cpuhp_lock_release();
319}
320
321/*
322 * Wait for currently running CPU hotplug operations to complete (if any) and
323 * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
324 * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
325 * hotplug path before performing hotplug operations. So acquiring that lock
326 * guarantees mutual exclusion from any currently running hotplug operations.
327 */
328void cpu_hotplug_disable(void)
329{
330 cpu_maps_update_begin();
331 cpu_hotplug_disabled++;
332 cpu_maps_update_done();
333}
334EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
335
336static void __cpu_hotplug_enable(void)
337{
338 if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
339 return;
340 cpu_hotplug_disabled--;
341}
342
343void cpu_hotplug_enable(void)
344{
345 cpu_maps_update_begin();
346 __cpu_hotplug_enable();
347 cpu_maps_update_done();
348}
349EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
350#endif /* CONFIG_HOTPLUG_CPU */
351
352/* Need to know about CPUs going up/down? */
353int register_cpu_notifier(struct notifier_block *nb)
354{
355 int ret;
356 cpu_maps_update_begin();
357 ret = raw_notifier_chain_register(&cpu_chain, nb);
358 cpu_maps_update_done();
359 return ret;
360}
361
362int __register_cpu_notifier(struct notifier_block *nb)
363{
364 return raw_notifier_chain_register(&cpu_chain, nb);
365}
366
367static int __cpu_notify(unsigned long val, unsigned int cpu, int nr_to_call,
368 int *nr_calls)
369{
370 unsigned long mod = cpuhp_tasks_frozen ? CPU_TASKS_FROZEN : 0;
371 void *hcpu = (void *)(long)cpu;
372
373 int ret;
374
375 ret = __raw_notifier_call_chain(&cpu_chain, val | mod, hcpu, nr_to_call,
376 nr_calls);
377
378 return notifier_to_errno(ret);
379}
380
381static int cpu_notify(unsigned long val, unsigned int cpu)
382{
383 return __cpu_notify(val, cpu, -1, NULL);
384}
385
386static void cpu_notify_nofail(unsigned long val, unsigned int cpu)
387{
388 BUG_ON(cpu_notify(val, cpu));
389}
390
391/* Notifier wrappers for transitioning to state machine */
392static int notify_prepare(unsigned int cpu)
393{
394 int nr_calls = 0;
395 int ret;
396
397 ret = __cpu_notify(CPU_UP_PREPARE, cpu, -1, &nr_calls);
398 if (ret) {
399 nr_calls--;
400 printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
401 __func__, cpu);
402 __cpu_notify(CPU_UP_CANCELED, cpu, nr_calls, NULL);
403 }
404 return ret;
405}
406
407static int notify_online(unsigned int cpu)
408{
409 cpu_notify(CPU_ONLINE, cpu);
410 return 0;
411}
412
413static int bringup_wait_for_ap(unsigned int cpu)
414{
415 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
416
417 wait_for_completion(&st->done);
418 return st->result;
419}
420
421static int bringup_cpu(unsigned int cpu)
422{
423 struct task_struct *idle = idle_thread_get(cpu);
424 int ret;
425
426 /*
427 * Some architectures have to walk the irq descriptors to
428 * setup the vector space for the cpu which comes online.
429 * Prevent irq alloc/free across the bringup.
430 */
431 irq_lock_sparse();
432
433 /* Arch-specific enabling code. */
434 ret = __cpu_up(cpu, idle);
435 irq_unlock_sparse();
436 if (ret) {
437 cpu_notify(CPU_UP_CANCELED, cpu);
438 return ret;
439 }
440 ret = bringup_wait_for_ap(cpu);
441 BUG_ON(!cpu_online(cpu));
442 return ret;
443}
444
445/*
446 * Hotplug state machine related functions
447 */
448static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st)
449{
450 for (st->state++; st->state < st->target; st->state++) {
451 struct cpuhp_step *step = cpuhp_get_step(st->state);
452
453 if (!step->skip_onerr)
454 cpuhp_invoke_callback(cpu, st->state, true, NULL);
455 }
456}
457
458static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
459 enum cpuhp_state target)
460{
461 enum cpuhp_state prev_state = st->state;
462 int ret = 0;
463
464 for (; st->state > target; st->state--) {
465 ret = cpuhp_invoke_callback(cpu, st->state, false, NULL);
466 if (ret) {
467 st->target = prev_state;
468 undo_cpu_down(cpu, st);
469 break;
470 }
471 }
472 return ret;
473}
474
475static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st)
476{
477 for (st->state--; st->state > st->target; st->state--) {
478 struct cpuhp_step *step = cpuhp_get_step(st->state);
479
480 if (!step->skip_onerr)
481 cpuhp_invoke_callback(cpu, st->state, false, NULL);
482 }
483}
484
485static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
486 enum cpuhp_state target)
487{
488 enum cpuhp_state prev_state = st->state;
489 int ret = 0;
490
491 while (st->state < target) {
492 st->state++;
493 ret = cpuhp_invoke_callback(cpu, st->state, true, NULL);
494 if (ret) {
495 st->target = prev_state;
496 undo_cpu_up(cpu, st);
497 break;
498 }
499 }
500 return ret;
501}
502
503/*
504 * The cpu hotplug threads manage the bringup and teardown of the cpus
505 */
506static void cpuhp_create(unsigned int cpu)
507{
508 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
509
510 init_completion(&st->done);
511}
512
513static int cpuhp_should_run(unsigned int cpu)
514{
515 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
516
517 return st->should_run;
518}
519
520/* Execute the teardown callbacks. Used to be CPU_DOWN_PREPARE */
521static int cpuhp_ap_offline(unsigned int cpu, struct cpuhp_cpu_state *st)
522{
523 enum cpuhp_state target = max((int)st->target, CPUHP_TEARDOWN_CPU);
524
525 return cpuhp_down_callbacks(cpu, st, target);
526}
527
528/* Execute the online startup callbacks. Used to be CPU_ONLINE */
529static int cpuhp_ap_online(unsigned int cpu, struct cpuhp_cpu_state *st)
530{
531 return cpuhp_up_callbacks(cpu, st, st->target);
532}
533
534/*
535 * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke
536 * callbacks when a state gets [un]installed at runtime.
537 */
538static void cpuhp_thread_fun(unsigned int cpu)
539{
540 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
541 int ret = 0;
542
543 /*
544 * Paired with the mb() in cpuhp_kick_ap_work and
545 * cpuhp_invoke_ap_callback, so the work set is consistent visible.
546 */
547 smp_mb();
548 if (!st->should_run)
549 return;
550
551 st->should_run = false;
552
553 /* Single callback invocation for [un]install ? */
554 if (st->single) {
555 if (st->cb_state < CPUHP_AP_ONLINE) {
556 local_irq_disable();
557 ret = cpuhp_invoke_callback(cpu, st->cb_state,
558 st->bringup, st->node);
559 local_irq_enable();
560 } else {
561 ret = cpuhp_invoke_callback(cpu, st->cb_state,
562 st->bringup, st->node);
563 }
564 } else if (st->rollback) {
565 BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE);
566
567 undo_cpu_down(cpu, st);
568 /*
569 * This is a momentary workaround to keep the notifier users
570 * happy. Will go away once we got rid of the notifiers.
571 */
572 cpu_notify_nofail(CPU_DOWN_FAILED, cpu);
573 st->rollback = false;
574 } else {
575 /* Cannot happen .... */
576 BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE);
577
578 /* Regular hotplug work */
579 if (st->state < st->target)
580 ret = cpuhp_ap_online(cpu, st);
581 else if (st->state > st->target)
582 ret = cpuhp_ap_offline(cpu, st);
583 }
584 st->result = ret;
585 complete(&st->done);
586}
587
588/* Invoke a single callback on a remote cpu */
589static int
590cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup,
591 struct hlist_node *node)
592{
593 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
594
595 if (!cpu_online(cpu))
596 return 0;
597
598 /*
599 * If we are up and running, use the hotplug thread. For early calls
600 * we invoke the thread function directly.
601 */
602 if (!st->thread)
603 return cpuhp_invoke_callback(cpu, state, bringup, node);
604
605 st->cb_state = state;
606 st->single = true;
607 st->bringup = bringup;
608 st->node = node;
609
610 /*
611 * Make sure the above stores are visible before should_run becomes
612 * true. Paired with the mb() above in cpuhp_thread_fun()
613 */
614 smp_mb();
615 st->should_run = true;
616 wake_up_process(st->thread);
617 wait_for_completion(&st->done);
618 return st->result;
619}
620
621/* Regular hotplug invocation of the AP hotplug thread */
622static void __cpuhp_kick_ap_work(struct cpuhp_cpu_state *st)
623{
624 st->result = 0;
625 st->single = false;
626 /*
627 * Make sure the above stores are visible before should_run becomes
628 * true. Paired with the mb() above in cpuhp_thread_fun()
629 */
630 smp_mb();
631 st->should_run = true;
632 wake_up_process(st->thread);
633}
634
635static int cpuhp_kick_ap_work(unsigned int cpu)
636{
637 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
638 enum cpuhp_state state = st->state;
639
640 trace_cpuhp_enter(cpu, st->target, state, cpuhp_kick_ap_work);
641 __cpuhp_kick_ap_work(st);
642 wait_for_completion(&st->done);
643 trace_cpuhp_exit(cpu, st->state, state, st->result);
644 return st->result;
645}
646
647static struct smp_hotplug_thread cpuhp_threads = {
648 .store = &cpuhp_state.thread,
649 .create = &cpuhp_create,
650 .thread_should_run = cpuhp_should_run,
651 .thread_fn = cpuhp_thread_fun,
652 .thread_comm = "cpuhp/%u",
653 .selfparking = true,
654};
655
656void __init cpuhp_threads_init(void)
657{
658 BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads));
659 kthread_unpark(this_cpu_read(cpuhp_state.thread));
660}
661
662#ifdef CONFIG_HOTPLUG_CPU
663EXPORT_SYMBOL(register_cpu_notifier);
664EXPORT_SYMBOL(__register_cpu_notifier);
665void unregister_cpu_notifier(struct notifier_block *nb)
666{
667 cpu_maps_update_begin();
668 raw_notifier_chain_unregister(&cpu_chain, nb);
669 cpu_maps_update_done();
670}
671EXPORT_SYMBOL(unregister_cpu_notifier);
672
673void __unregister_cpu_notifier(struct notifier_block *nb)
674{
675 raw_notifier_chain_unregister(&cpu_chain, nb);
676}
677EXPORT_SYMBOL(__unregister_cpu_notifier);
678
679/**
680 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
681 * @cpu: a CPU id
682 *
683 * This function walks all processes, finds a valid mm struct for each one and
684 * then clears a corresponding bit in mm's cpumask. While this all sounds
685 * trivial, there are various non-obvious corner cases, which this function
686 * tries to solve in a safe manner.
687 *
688 * Also note that the function uses a somewhat relaxed locking scheme, so it may
689 * be called only for an already offlined CPU.
690 */
691void clear_tasks_mm_cpumask(int cpu)
692{
693 struct task_struct *p;
694
695 /*
696 * This function is called after the cpu is taken down and marked
697 * offline, so its not like new tasks will ever get this cpu set in
698 * their mm mask. -- Peter Zijlstra
699 * Thus, we may use rcu_read_lock() here, instead of grabbing
700 * full-fledged tasklist_lock.
701 */
702 WARN_ON(cpu_online(cpu));
703 rcu_read_lock();
704 for_each_process(p) {
705 struct task_struct *t;
706
707 /*
708 * Main thread might exit, but other threads may still have
709 * a valid mm. Find one.
710 */
711 t = find_lock_task_mm(p);
712 if (!t)
713 continue;
714 cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
715 task_unlock(t);
716 }
717 rcu_read_unlock();
718}
719
720static inline void check_for_tasks(int dead_cpu)
721{
722 struct task_struct *g, *p;
723
724 read_lock(&tasklist_lock);
725 for_each_process_thread(g, p) {
726 if (!p->on_rq)
727 continue;
728 /*
729 * We do the check with unlocked task_rq(p)->lock.
730 * Order the reading to do not warn about a task,
731 * which was running on this cpu in the past, and
732 * it's just been woken on another cpu.
733 */
734 rmb();
735 if (task_cpu(p) != dead_cpu)
736 continue;
737
738 pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
739 p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
740 }
741 read_unlock(&tasklist_lock);
742}
743
744static int notify_down_prepare(unsigned int cpu)
745{
746 int err, nr_calls = 0;
747
748 err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls);
749 if (err) {
750 nr_calls--;
751 __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL);
752 pr_warn("%s: attempt to take down CPU %u failed\n",
753 __func__, cpu);
754 }
755 return err;
756}
757
758/* Take this CPU down. */
759static int take_cpu_down(void *_param)
760{
761 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
762 enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE);
763 int err, cpu = smp_processor_id();
764
765 /* Ensure this CPU doesn't handle any more interrupts. */
766 err = __cpu_disable();
767 if (err < 0)
768 return err;
769
770 /*
771 * We get here while we are in CPUHP_TEARDOWN_CPU state and we must not
772 * do this step again.
773 */
774 WARN_ON(st->state != CPUHP_TEARDOWN_CPU);
775 st->state--;
776 /* Invoke the former CPU_DYING callbacks */
777 for (; st->state > target; st->state--)
778 cpuhp_invoke_callback(cpu, st->state, false, NULL);
779
780 /* Give up timekeeping duties */
781 tick_handover_do_timer();
782 /* Park the stopper thread */
783 stop_machine_park(cpu);
784 return 0;
785}
786
787static int takedown_cpu(unsigned int cpu)
788{
789 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
790 int err;
791
792 /* Park the smpboot threads */
793 kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread);
794 smpboot_park_threads(cpu);
795
796 /*
797 * Prevent irq alloc/free while the dying cpu reorganizes the
798 * interrupt affinities.
799 */
800 irq_lock_sparse();
801
802 /*
803 * So now all preempt/rcu users must observe !cpu_active().
804 */
805 err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu));
806 if (err) {
807 /* CPU refused to die */
808 irq_unlock_sparse();
809 /* Unpark the hotplug thread so we can rollback there */
810 kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread);
811 return err;
812 }
813 BUG_ON(cpu_online(cpu));
814
815 /*
816 * The CPUHP_AP_SCHED_MIGRATE_DYING callback will have removed all
817 * runnable tasks from the cpu, there's only the idle task left now
818 * that the migration thread is done doing the stop_machine thing.
819 *
820 * Wait for the stop thread to go away.
821 */
822 wait_for_completion(&st->done);
823 BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
824
825 /* Interrupts are moved away from the dying cpu, reenable alloc/free */
826 irq_unlock_sparse();
827
828 hotplug_cpu__broadcast_tick_pull(cpu);
829 /* This actually kills the CPU. */
830 __cpu_die(cpu);
831
832 tick_cleanup_dead_cpu(cpu);
833 return 0;
834}
835
836static int notify_dead(unsigned int cpu)
837{
838 cpu_notify_nofail(CPU_DEAD, cpu);
839 check_for_tasks(cpu);
840 return 0;
841}
842
843static void cpuhp_complete_idle_dead(void *arg)
844{
845 struct cpuhp_cpu_state *st = arg;
846
847 complete(&st->done);
848}
849
850void cpuhp_report_idle_dead(void)
851{
852 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
853
854 BUG_ON(st->state != CPUHP_AP_OFFLINE);
855 rcu_report_dead(smp_processor_id());
856 st->state = CPUHP_AP_IDLE_DEAD;
857 /*
858 * We cannot call complete after rcu_report_dead() so we delegate it
859 * to an online cpu.
860 */
861 smp_call_function_single(cpumask_first(cpu_online_mask),
862 cpuhp_complete_idle_dead, st, 0);
863}
864
865#else
866#define notify_down_prepare NULL
867#define takedown_cpu NULL
868#define notify_dead NULL
869#endif
870
871#ifdef CONFIG_HOTPLUG_CPU
872
873/* Requires cpu_add_remove_lock to be held */
874static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
875 enum cpuhp_state target)
876{
877 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
878 int prev_state, ret = 0;
879 bool hasdied = false;
880
881 if (num_online_cpus() == 1)
882 return -EBUSY;
883
884 if (!cpu_present(cpu))
885 return -EINVAL;
886
887 cpu_hotplug_begin();
888
889 cpuhp_tasks_frozen = tasks_frozen;
890
891 prev_state = st->state;
892 st->target = target;
893 /*
894 * If the current CPU state is in the range of the AP hotplug thread,
895 * then we need to kick the thread.
896 */
897 if (st->state > CPUHP_TEARDOWN_CPU) {
898 ret = cpuhp_kick_ap_work(cpu);
899 /*
900 * The AP side has done the error rollback already. Just
901 * return the error code..
902 */
903 if (ret)
904 goto out;
905
906 /*
907 * We might have stopped still in the range of the AP hotplug
908 * thread. Nothing to do anymore.
909 */
910 if (st->state > CPUHP_TEARDOWN_CPU)
911 goto out;
912 }
913 /*
914 * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need
915 * to do the further cleanups.
916 */
917 ret = cpuhp_down_callbacks(cpu, st, target);
918 if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) {
919 st->target = prev_state;
920 st->rollback = true;
921 cpuhp_kick_ap_work(cpu);
922 }
923
924 hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE;
925out:
926 cpu_hotplug_done();
927 /* This post dead nonsense must die */
928 if (!ret && hasdied)
929 cpu_notify_nofail(CPU_POST_DEAD, cpu);
930 return ret;
931}
932
933static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
934{
935 int err;
936
937 cpu_maps_update_begin();
938
939 if (cpu_hotplug_disabled) {
940 err = -EBUSY;
941 goto out;
942 }
943
944 err = _cpu_down(cpu, 0, target);
945
946out:
947 cpu_maps_update_done();
948 return err;
949}
950int cpu_down(unsigned int cpu)
951{
952 return do_cpu_down(cpu, CPUHP_OFFLINE);
953}
954EXPORT_SYMBOL(cpu_down);
955#endif /*CONFIG_HOTPLUG_CPU*/
956
957/**
958 * notify_cpu_starting(cpu) - Invoke the callbacks on the starting CPU
959 * @cpu: cpu that just started
960 *
961 * It must be called by the arch code on the new cpu, before the new cpu
962 * enables interrupts and before the "boot" cpu returns from __cpu_up().
963 */
964void notify_cpu_starting(unsigned int cpu)
965{
966 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
967 enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
968
969 rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */
970 while (st->state < target) {
971 st->state++;
972 cpuhp_invoke_callback(cpu, st->state, true, NULL);
973 }
974}
975
976/*
977 * Called from the idle task. We need to set active here, so we can kick off
978 * the stopper thread and unpark the smpboot threads. If the target state is
979 * beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the
980 * cpu further.
981 */
982void cpuhp_online_idle(enum cpuhp_state state)
983{
984 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
985 unsigned int cpu = smp_processor_id();
986
987 /* Happens for the boot cpu */
988 if (state != CPUHP_AP_ONLINE_IDLE)
989 return;
990
991 st->state = CPUHP_AP_ONLINE_IDLE;
992
993 /* Unpark the stopper thread and the hotplug thread of this cpu */
994 stop_machine_unpark(cpu);
995 kthread_unpark(st->thread);
996
997 /* Should we go further up ? */
998 if (st->target > CPUHP_AP_ONLINE_IDLE)
999 __cpuhp_kick_ap_work(st);
1000 else
1001 complete(&st->done);
1002}
1003
1004/* Requires cpu_add_remove_lock to be held */
1005static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
1006{
1007 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1008 struct task_struct *idle;
1009 int ret = 0;
1010
1011 cpu_hotplug_begin();
1012
1013 if (!cpu_present(cpu)) {
1014 ret = -EINVAL;
1015 goto out;
1016 }
1017
1018 /*
1019 * The caller of do_cpu_up might have raced with another
1020 * caller. Ignore it for now.
1021 */
1022 if (st->state >= target)
1023 goto out;
1024
1025 if (st->state == CPUHP_OFFLINE) {
1026 /* Let it fail before we try to bring the cpu up */
1027 idle = idle_thread_get(cpu);
1028 if (IS_ERR(idle)) {
1029 ret = PTR_ERR(idle);
1030 goto out;
1031 }
1032 }
1033
1034 cpuhp_tasks_frozen = tasks_frozen;
1035
1036 st->target = target;
1037 /*
1038 * If the current CPU state is in the range of the AP hotplug thread,
1039 * then we need to kick the thread once more.
1040 */
1041 if (st->state > CPUHP_BRINGUP_CPU) {
1042 ret = cpuhp_kick_ap_work(cpu);
1043 /*
1044 * The AP side has done the error rollback already. Just
1045 * return the error code..
1046 */
1047 if (ret)
1048 goto out;
1049 }
1050
1051 /*
1052 * Try to reach the target state. We max out on the BP at
1053 * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
1054 * responsible for bringing it up to the target state.
1055 */
1056 target = min((int)target, CPUHP_BRINGUP_CPU);
1057 ret = cpuhp_up_callbacks(cpu, st, target);
1058out:
1059 cpu_hotplug_done();
1060 return ret;
1061}
1062
1063static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
1064{
1065 int err = 0;
1066
1067 if (!cpu_possible(cpu)) {
1068 pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
1069 cpu);
1070#if defined(CONFIG_IA64)
1071 pr_err("please check additional_cpus= boot parameter\n");
1072#endif
1073 return -EINVAL;
1074 }
1075
1076 err = try_online_node(cpu_to_node(cpu));
1077 if (err)
1078 return err;
1079
1080 cpu_maps_update_begin();
1081
1082 if (cpu_hotplug_disabled) {
1083 err = -EBUSY;
1084 goto out;
1085 }
1086
1087 err = _cpu_up(cpu, 0, target);
1088out:
1089 cpu_maps_update_done();
1090 return err;
1091}
1092
1093int cpu_up(unsigned int cpu)
1094{
1095 return do_cpu_up(cpu, CPUHP_ONLINE);
1096}
1097EXPORT_SYMBOL_GPL(cpu_up);
1098
1099#ifdef CONFIG_PM_SLEEP_SMP
1100static cpumask_var_t frozen_cpus;
1101
1102int freeze_secondary_cpus(int primary)
1103{
1104 int cpu, error = 0;
1105
1106 cpu_maps_update_begin();
1107 if (!cpu_online(primary))
1108 primary = cpumask_first(cpu_online_mask);
1109 /*
1110 * We take down all of the non-boot CPUs in one shot to avoid races
1111 * with the userspace trying to use the CPU hotplug at the same time
1112 */
1113 cpumask_clear(frozen_cpus);
1114
1115 pr_info("Disabling non-boot CPUs ...\n");
1116 for_each_online_cpu(cpu) {
1117 if (cpu == primary)
1118 continue;
1119 trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
1120 error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
1121 trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
1122 if (!error)
1123 cpumask_set_cpu(cpu, frozen_cpus);
1124 else {
1125 pr_err("Error taking CPU%d down: %d\n", cpu, error);
1126 break;
1127 }
1128 }
1129
1130 if (!error)
1131 BUG_ON(num_online_cpus() > 1);
1132 else
1133 pr_err("Non-boot CPUs are not disabled\n");
1134
1135 /*
1136 * Make sure the CPUs won't be enabled by someone else. We need to do
1137 * this even in case of failure as all disable_nonboot_cpus() users are
1138 * supposed to do enable_nonboot_cpus() on the failure path.
1139 */
1140 cpu_hotplug_disabled++;
1141
1142 cpu_maps_update_done();
1143 return error;
1144}
1145
1146void __weak arch_enable_nonboot_cpus_begin(void)
1147{
1148}
1149
1150void __weak arch_enable_nonboot_cpus_end(void)
1151{
1152}
1153
1154void enable_nonboot_cpus(void)
1155{
1156 int cpu, error;
1157
1158 /* Allow everyone to use the CPU hotplug again */
1159 cpu_maps_update_begin();
1160 __cpu_hotplug_enable();
1161 if (cpumask_empty(frozen_cpus))
1162 goto out;
1163
1164 pr_info("Enabling non-boot CPUs ...\n");
1165
1166 arch_enable_nonboot_cpus_begin();
1167
1168 for_each_cpu(cpu, frozen_cpus) {
1169 trace_suspend_resume(TPS("CPU_ON"), cpu, true);
1170 error = _cpu_up(cpu, 1, CPUHP_ONLINE);
1171 trace_suspend_resume(TPS("CPU_ON"), cpu, false);
1172 if (!error) {
1173 pr_info("CPU%d is up\n", cpu);
1174 continue;
1175 }
1176 pr_warn("Error taking CPU%d up: %d\n", cpu, error);
1177 }
1178
1179 arch_enable_nonboot_cpus_end();
1180
1181 cpumask_clear(frozen_cpus);
1182out:
1183 cpu_maps_update_done();
1184}
1185
1186static int __init alloc_frozen_cpus(void)
1187{
1188 if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
1189 return -ENOMEM;
1190 return 0;
1191}
1192core_initcall(alloc_frozen_cpus);
1193
1194/*
1195 * When callbacks for CPU hotplug notifications are being executed, we must
1196 * ensure that the state of the system with respect to the tasks being frozen
1197 * or not, as reported by the notification, remains unchanged *throughout the
1198 * duration* of the execution of the callbacks.
1199 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
1200 *
1201 * This synchronization is implemented by mutually excluding regular CPU
1202 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
1203 * Hibernate notifications.
1204 */
1205static int
1206cpu_hotplug_pm_callback(struct notifier_block *nb,
1207 unsigned long action, void *ptr)
1208{
1209 switch (action) {
1210
1211 case PM_SUSPEND_PREPARE:
1212 case PM_HIBERNATION_PREPARE:
1213 cpu_hotplug_disable();
1214 break;
1215
1216 case PM_POST_SUSPEND:
1217 case PM_POST_HIBERNATION:
1218 cpu_hotplug_enable();
1219 break;
1220
1221 default:
1222 return NOTIFY_DONE;
1223 }
1224
1225 return NOTIFY_OK;
1226}
1227
1228
1229static int __init cpu_hotplug_pm_sync_init(void)
1230{
1231 /*
1232 * cpu_hotplug_pm_callback has higher priority than x86
1233 * bsp_pm_callback which depends on cpu_hotplug_pm_callback
1234 * to disable cpu hotplug to avoid cpu hotplug race.
1235 */
1236 pm_notifier(cpu_hotplug_pm_callback, 0);
1237 return 0;
1238}
1239core_initcall(cpu_hotplug_pm_sync_init);
1240
1241#endif /* CONFIG_PM_SLEEP_SMP */
1242
1243#endif /* CONFIG_SMP */
1244
1245/* Boot processor state steps */
1246static struct cpuhp_step cpuhp_bp_states[] = {
1247 [CPUHP_OFFLINE] = {
1248 .name = "offline",
1249 .startup.single = NULL,
1250 .teardown.single = NULL,
1251 },
1252#ifdef CONFIG_SMP
1253 [CPUHP_CREATE_THREADS]= {
1254 .name = "threads:prepare",
1255 .startup.single = smpboot_create_threads,
1256 .teardown.single = NULL,
1257 .cant_stop = true,
1258 },
1259 [CPUHP_PERF_PREPARE] = {
1260 .name = "perf:prepare",
1261 .startup.single = perf_event_init_cpu,
1262 .teardown.single = perf_event_exit_cpu,
1263 },
1264 [CPUHP_WORKQUEUE_PREP] = {
1265 .name = "workqueue:prepare",
1266 .startup.single = workqueue_prepare_cpu,
1267 .teardown.single = NULL,
1268 },
1269 [CPUHP_HRTIMERS_PREPARE] = {
1270 .name = "hrtimers:prepare",
1271 .startup.single = hrtimers_prepare_cpu,
1272 .teardown.single = hrtimers_dead_cpu,
1273 },
1274 [CPUHP_SMPCFD_PREPARE] = {
1275 .name = "smpcfd:prepare",
1276 .startup.single = smpcfd_prepare_cpu,
1277 .teardown.single = smpcfd_dead_cpu,
1278 },
1279 [CPUHP_RELAY_PREPARE] = {
1280 .name = "relay:prepare",
1281 .startup.single = relay_prepare_cpu,
1282 .teardown.single = NULL,
1283 },
1284 [CPUHP_SLAB_PREPARE] = {
1285 .name = "slab:prepare",
1286 .startup.single = slab_prepare_cpu,
1287 .teardown.single = slab_dead_cpu,
1288 },
1289 [CPUHP_RCUTREE_PREP] = {
1290 .name = "RCU/tree:prepare",
1291 .startup.single = rcutree_prepare_cpu,
1292 .teardown.single = rcutree_dead_cpu,
1293 },
1294 /*
1295 * Preparatory and dead notifiers. Will be replaced once the notifiers
1296 * are converted to states.
1297 */
1298 [CPUHP_NOTIFY_PREPARE] = {
1299 .name = "notify:prepare",
1300 .startup.single = notify_prepare,
1301 .teardown.single = notify_dead,
1302 .skip_onerr = true,
1303 .cant_stop = true,
1304 },
1305 /*
1306 * On the tear-down path, timers_dead_cpu() must be invoked
1307 * before blk_mq_queue_reinit_notify() from notify_dead(),
1308 * otherwise a RCU stall occurs.
1309 */
1310 [CPUHP_TIMERS_DEAD] = {
1311 .name = "timers:dead",
1312 .startup.single = NULL,
1313 .teardown.single = timers_dead_cpu,
1314 },
1315 /* Kicks the plugged cpu into life */
1316 [CPUHP_BRINGUP_CPU] = {
1317 .name = "cpu:bringup",
1318 .startup.single = bringup_cpu,
1319 .teardown.single = NULL,
1320 .cant_stop = true,
1321 },
1322 [CPUHP_AP_SMPCFD_DYING] = {
1323 .name = "smpcfd:dying",
1324 .startup.single = NULL,
1325 .teardown.single = smpcfd_dying_cpu,
1326 },
1327 /*
1328 * Handled on controll processor until the plugged processor manages
1329 * this itself.
1330 */
1331 [CPUHP_TEARDOWN_CPU] = {
1332 .name = "cpu:teardown",
1333 .startup.single = NULL,
1334 .teardown.single = takedown_cpu,
1335 .cant_stop = true,
1336 },
1337#else
1338 [CPUHP_BRINGUP_CPU] = { },
1339#endif
1340};
1341
1342/* Application processor state steps */
1343static struct cpuhp_step cpuhp_ap_states[] = {
1344#ifdef CONFIG_SMP
1345 /* Final state before CPU kills itself */
1346 [CPUHP_AP_IDLE_DEAD] = {
1347 .name = "idle:dead",
1348 },
1349 /*
1350 * Last state before CPU enters the idle loop to die. Transient state
1351 * for synchronization.
1352 */
1353 [CPUHP_AP_OFFLINE] = {
1354 .name = "ap:offline",
1355 .cant_stop = true,
1356 },
1357 /* First state is scheduler control. Interrupts are disabled */
1358 [CPUHP_AP_SCHED_STARTING] = {
1359 .name = "sched:starting",
1360 .startup.single = sched_cpu_starting,
1361 .teardown.single = sched_cpu_dying,
1362 },
1363 [CPUHP_AP_RCUTREE_DYING] = {
1364 .name = "RCU/tree:dying",
1365 .startup.single = NULL,
1366 .teardown.single = rcutree_dying_cpu,
1367 },
1368 /* Entry state on starting. Interrupts enabled from here on. Transient
1369 * state for synchronsization */
1370 [CPUHP_AP_ONLINE] = {
1371 .name = "ap:online",
1372 },
1373 /* Handle smpboot threads park/unpark */
1374 [CPUHP_AP_SMPBOOT_THREADS] = {
1375 .name = "smpboot/threads:online",
1376 .startup.single = smpboot_unpark_threads,
1377 .teardown.single = NULL,
1378 },
1379 [CPUHP_AP_PERF_ONLINE] = {
1380 .name = "perf:online",
1381 .startup.single = perf_event_init_cpu,
1382 .teardown.single = perf_event_exit_cpu,
1383 },
1384 [CPUHP_AP_WORKQUEUE_ONLINE] = {
1385 .name = "workqueue:online",
1386 .startup.single = workqueue_online_cpu,
1387 .teardown.single = workqueue_offline_cpu,
1388 },
1389 [CPUHP_AP_RCUTREE_ONLINE] = {
1390 .name = "RCU/tree:online",
1391 .startup.single = rcutree_online_cpu,
1392 .teardown.single = rcutree_offline_cpu,
1393 },
1394
1395 /*
1396 * Online/down_prepare notifiers. Will be removed once the notifiers
1397 * are converted to states.
1398 */
1399 [CPUHP_AP_NOTIFY_ONLINE] = {
1400 .name = "notify:online",
1401 .startup.single = notify_online,
1402 .teardown.single = notify_down_prepare,
1403 .skip_onerr = true,
1404 },
1405#endif
1406 /*
1407 * The dynamically registered state space is here
1408 */
1409
1410#ifdef CONFIG_SMP
1411 /* Last state is scheduler control setting the cpu active */
1412 [CPUHP_AP_ACTIVE] = {
1413 .name = "sched:active",
1414 .startup.single = sched_cpu_activate,
1415 .teardown.single = sched_cpu_deactivate,
1416 },
1417#endif
1418
1419 /* CPU is fully up and running. */
1420 [CPUHP_ONLINE] = {
1421 .name = "online",
1422 .startup.single = NULL,
1423 .teardown.single = NULL,
1424 },
1425};
1426
1427/* Sanity check for callbacks */
1428static int cpuhp_cb_check(enum cpuhp_state state)
1429{
1430 if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
1431 return -EINVAL;
1432 return 0;
1433}
1434
1435static void cpuhp_store_callbacks(enum cpuhp_state state,
1436 const char *name,
1437 int (*startup)(unsigned int cpu),
1438 int (*teardown)(unsigned int cpu),
1439 bool multi_instance)
1440{
1441 /* (Un)Install the callbacks for further cpu hotplug operations */
1442 struct cpuhp_step *sp;
1443
1444 mutex_lock(&cpuhp_state_mutex);
1445 sp = cpuhp_get_step(state);
1446 sp->startup.single = startup;
1447 sp->teardown.single = teardown;
1448 sp->name = name;
1449 sp->multi_instance = multi_instance;
1450 INIT_HLIST_HEAD(&sp->list);
1451 mutex_unlock(&cpuhp_state_mutex);
1452}
1453
1454static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
1455{
1456 return cpuhp_get_step(state)->teardown.single;
1457}
1458
1459/*
1460 * Call the startup/teardown function for a step either on the AP or
1461 * on the current CPU.
1462 */
1463static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup,
1464 struct hlist_node *node)
1465{
1466 struct cpuhp_step *sp = cpuhp_get_step(state);
1467 int ret;
1468
1469 if ((bringup && !sp->startup.single) ||
1470 (!bringup && !sp->teardown.single))
1471 return 0;
1472 /*
1473 * The non AP bound callbacks can fail on bringup. On teardown
1474 * e.g. module removal we crash for now.
1475 */
1476#ifdef CONFIG_SMP
1477 if (cpuhp_is_ap_state(state))
1478 ret = cpuhp_invoke_ap_callback(cpu, state, bringup, node);
1479 else
1480 ret = cpuhp_invoke_callback(cpu, state, bringup, node);
1481#else
1482 ret = cpuhp_invoke_callback(cpu, state, bringup, node);
1483#endif
1484 BUG_ON(ret && !bringup);
1485 return ret;
1486}
1487
1488/*
1489 * Called from __cpuhp_setup_state on a recoverable failure.
1490 *
1491 * Note: The teardown callbacks for rollback are not allowed to fail!
1492 */
1493static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
1494 struct hlist_node *node)
1495{
1496 int cpu;
1497
1498 /* Roll back the already executed steps on the other cpus */
1499 for_each_present_cpu(cpu) {
1500 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1501 int cpustate = st->state;
1502
1503 if (cpu >= failedcpu)
1504 break;
1505
1506 /* Did we invoke the startup call on that cpu ? */
1507 if (cpustate >= state)
1508 cpuhp_issue_call(cpu, state, false, node);
1509 }
1510}
1511
1512/*
1513 * Returns a free for dynamic slot assignment of the Online state. The states
1514 * are protected by the cpuhp_slot_states mutex and an empty slot is identified
1515 * by having no name assigned.
1516 */
1517static int cpuhp_reserve_state(enum cpuhp_state state)
1518{
1519 enum cpuhp_state i;
1520
1521 mutex_lock(&cpuhp_state_mutex);
1522 for (i = CPUHP_AP_ONLINE_DYN; i <= CPUHP_AP_ONLINE_DYN_END; i++) {
1523 if (cpuhp_ap_states[i].name)
1524 continue;
1525
1526 cpuhp_ap_states[i].name = "Reserved";
1527 mutex_unlock(&cpuhp_state_mutex);
1528 return i;
1529 }
1530 mutex_unlock(&cpuhp_state_mutex);
1531 WARN(1, "No more dynamic states available for CPU hotplug\n");
1532 return -ENOSPC;
1533}
1534
1535int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
1536 bool invoke)
1537{
1538 struct cpuhp_step *sp;
1539 int cpu;
1540 int ret;
1541
1542 sp = cpuhp_get_step(state);
1543 if (sp->multi_instance == false)
1544 return -EINVAL;
1545
1546 get_online_cpus();
1547
1548 if (!invoke || !sp->startup.multi)
1549 goto add_node;
1550
1551 /*
1552 * Try to call the startup callback for each present cpu
1553 * depending on the hotplug state of the cpu.
1554 */
1555 for_each_present_cpu(cpu) {
1556 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1557 int cpustate = st->state;
1558
1559 if (cpustate < state)
1560 continue;
1561
1562 ret = cpuhp_issue_call(cpu, state, true, node);
1563 if (ret) {
1564 if (sp->teardown.multi)
1565 cpuhp_rollback_install(cpu, state, node);
1566 goto err;
1567 }
1568 }
1569add_node:
1570 ret = 0;
1571 mutex_lock(&cpuhp_state_mutex);
1572 hlist_add_head(node, &sp->list);
1573 mutex_unlock(&cpuhp_state_mutex);
1574
1575err:
1576 put_online_cpus();
1577 return ret;
1578}
1579EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
1580
1581/**
1582 * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state
1583 * @state: The state to setup
1584 * @invoke: If true, the startup function is invoked for cpus where
1585 * cpu state >= @state
1586 * @startup: startup callback function
1587 * @teardown: teardown callback function
1588 *
1589 * Returns 0 if successful, otherwise a proper error code
1590 */
1591int __cpuhp_setup_state(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 int dyn_state = 0;
1599
1600 if (cpuhp_cb_check(state) || !name)
1601 return -EINVAL;
1602
1603 get_online_cpus();
1604
1605 /* currently assignments for the ONLINE state are possible */
1606 if (state == CPUHP_AP_ONLINE_DYN) {
1607 dyn_state = 1;
1608 ret = cpuhp_reserve_state(state);
1609 if (ret < 0)
1610 goto out;
1611 state = ret;
1612 }
1613
1614 cpuhp_store_callbacks(state, name, startup, teardown, multi_instance);
1615
1616 if (!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 put_online_cpus();
1640 if (!ret && dyn_state)
1641 return state;
1642 return ret;
1643}
1644EXPORT_SYMBOL(__cpuhp_setup_state);
1645
1646int __cpuhp_state_remove_instance(enum cpuhp_state state,
1647 struct hlist_node *node, bool invoke)
1648{
1649 struct cpuhp_step *sp = cpuhp_get_step(state);
1650 int cpu;
1651
1652 BUG_ON(cpuhp_cb_check(state));
1653
1654 if (!sp->multi_instance)
1655 return -EINVAL;
1656
1657 get_online_cpus();
1658 if (!invoke || !cpuhp_get_teardown_cb(state))
1659 goto remove;
1660 /*
1661 * Call the teardown callback for each present cpu depending
1662 * on the hotplug state of the cpu. This function is not
1663 * allowed to fail currently!
1664 */
1665 for_each_present_cpu(cpu) {
1666 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1667 int cpustate = st->state;
1668
1669 if (cpustate >= state)
1670 cpuhp_issue_call(cpu, state, false, node);
1671 }
1672
1673remove:
1674 mutex_lock(&cpuhp_state_mutex);
1675 hlist_del(node);
1676 mutex_unlock(&cpuhp_state_mutex);
1677 put_online_cpus();
1678
1679 return 0;
1680}
1681EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance);
1682/**
1683 * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state
1684 * @state: The state to remove
1685 * @invoke: If true, the teardown function is invoked for cpus where
1686 * cpu state >= @state
1687 *
1688 * The teardown callback is currently not allowed to fail. Think
1689 * about module removal!
1690 */
1691void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
1692{
1693 struct cpuhp_step *sp = cpuhp_get_step(state);
1694 int cpu;
1695
1696 BUG_ON(cpuhp_cb_check(state));
1697
1698 get_online_cpus();
1699
1700 if (sp->multi_instance) {
1701 WARN(!hlist_empty(&sp->list),
1702 "Error: Removing state %d which has instances left.\n",
1703 state);
1704 goto remove;
1705 }
1706
1707 if (!invoke || !cpuhp_get_teardown_cb(state))
1708 goto remove;
1709
1710 /*
1711 * Call the teardown callback for each present cpu depending
1712 * on the hotplug state of the cpu. This function is not
1713 * allowed to fail currently!
1714 */
1715 for_each_present_cpu(cpu) {
1716 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1717 int cpustate = st->state;
1718
1719 if (cpustate >= state)
1720 cpuhp_issue_call(cpu, state, false, NULL);
1721 }
1722remove:
1723 cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
1724 put_online_cpus();
1725}
1726EXPORT_SYMBOL(__cpuhp_remove_state);
1727
1728#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
1729static ssize_t show_cpuhp_state(struct device *dev,
1730 struct device_attribute *attr, char *buf)
1731{
1732 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1733
1734 return sprintf(buf, "%d\n", st->state);
1735}
1736static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
1737
1738static ssize_t write_cpuhp_target(struct device *dev,
1739 struct device_attribute *attr,
1740 const char *buf, size_t count)
1741{
1742 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1743 struct cpuhp_step *sp;
1744 int target, ret;
1745
1746 ret = kstrtoint(buf, 10, &target);
1747 if (ret)
1748 return ret;
1749
1750#ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
1751 if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
1752 return -EINVAL;
1753#else
1754 if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
1755 return -EINVAL;
1756#endif
1757
1758 ret = lock_device_hotplug_sysfs();
1759 if (ret)
1760 return ret;
1761
1762 mutex_lock(&cpuhp_state_mutex);
1763 sp = cpuhp_get_step(target);
1764 ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
1765 mutex_unlock(&cpuhp_state_mutex);
1766 if (ret)
1767 return ret;
1768
1769 if (st->state < target)
1770 ret = do_cpu_up(dev->id, target);
1771 else
1772 ret = do_cpu_down(dev->id, target);
1773
1774 unlock_device_hotplug();
1775 return ret ? ret : count;
1776}
1777
1778static ssize_t show_cpuhp_target(struct device *dev,
1779 struct device_attribute *attr, char *buf)
1780{
1781 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1782
1783 return sprintf(buf, "%d\n", st->target);
1784}
1785static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
1786
1787static struct attribute *cpuhp_cpu_attrs[] = {
1788 &dev_attr_state.attr,
1789 &dev_attr_target.attr,
1790 NULL
1791};
1792
1793static struct attribute_group cpuhp_cpu_attr_group = {
1794 .attrs = cpuhp_cpu_attrs,
1795 .name = "hotplug",
1796 NULL
1797};
1798
1799static ssize_t show_cpuhp_states(struct device *dev,
1800 struct device_attribute *attr, char *buf)
1801{
1802 ssize_t cur, res = 0;
1803 int i;
1804
1805 mutex_lock(&cpuhp_state_mutex);
1806 for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
1807 struct cpuhp_step *sp = cpuhp_get_step(i);
1808
1809 if (sp->name) {
1810 cur = sprintf(buf, "%3d: %s\n", i, sp->name);
1811 buf += cur;
1812 res += cur;
1813 }
1814 }
1815 mutex_unlock(&cpuhp_state_mutex);
1816 return res;
1817}
1818static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);
1819
1820static struct attribute *cpuhp_cpu_root_attrs[] = {
1821 &dev_attr_states.attr,
1822 NULL
1823};
1824
1825static struct attribute_group cpuhp_cpu_root_attr_group = {
1826 .attrs = cpuhp_cpu_root_attrs,
1827 .name = "hotplug",
1828 NULL
1829};
1830
1831static int __init cpuhp_sysfs_init(void)
1832{
1833 int cpu, ret;
1834
1835 ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
1836 &cpuhp_cpu_root_attr_group);
1837 if (ret)
1838 return ret;
1839
1840 for_each_possible_cpu(cpu) {
1841 struct device *dev = get_cpu_device(cpu);
1842
1843 if (!dev)
1844 continue;
1845 ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);
1846 if (ret)
1847 return ret;
1848 }
1849 return 0;
1850}
1851device_initcall(cpuhp_sysfs_init);
1852#endif
1853
1854/*
1855 * cpu_bit_bitmap[] is a special, "compressed" data structure that
1856 * represents all NR_CPUS bits binary values of 1<<nr.
1857 *
1858 * It is used by cpumask_of() to get a constant address to a CPU
1859 * mask value that has a single bit set only.
1860 */
1861
1862/* cpu_bit_bitmap[0] is empty - so we can back into it */
1863#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
1864#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
1865#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
1866#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
1867
1868const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
1869
1870 MASK_DECLARE_8(0), MASK_DECLARE_8(8),
1871 MASK_DECLARE_8(16), MASK_DECLARE_8(24),
1872#if BITS_PER_LONG > 32
1873 MASK_DECLARE_8(32), MASK_DECLARE_8(40),
1874 MASK_DECLARE_8(48), MASK_DECLARE_8(56),
1875#endif
1876};
1877EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
1878
1879const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
1880EXPORT_SYMBOL(cpu_all_bits);
1881
1882#ifdef CONFIG_INIT_ALL_POSSIBLE
1883struct cpumask __cpu_possible_mask __read_mostly
1884 = {CPU_BITS_ALL};
1885#else
1886struct cpumask __cpu_possible_mask __read_mostly;
1887#endif
1888EXPORT_SYMBOL(__cpu_possible_mask);
1889
1890struct cpumask __cpu_online_mask __read_mostly;
1891EXPORT_SYMBOL(__cpu_online_mask);
1892
1893struct cpumask __cpu_present_mask __read_mostly;
1894EXPORT_SYMBOL(__cpu_present_mask);
1895
1896struct cpumask __cpu_active_mask __read_mostly;
1897EXPORT_SYMBOL(__cpu_active_mask);
1898
1899void init_cpu_present(const struct cpumask *src)
1900{
1901 cpumask_copy(&__cpu_present_mask, src);
1902}
1903
1904void init_cpu_possible(const struct cpumask *src)
1905{
1906 cpumask_copy(&__cpu_possible_mask, src);
1907}
1908
1909void init_cpu_online(const struct cpumask *src)
1910{
1911 cpumask_copy(&__cpu_online_mask, src);
1912}
1913
1914/*
1915 * Activate the first processor.
1916 */
1917void __init boot_cpu_init(void)
1918{
1919 int cpu = smp_processor_id();
1920
1921 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
1922 set_cpu_online(cpu, true);
1923 set_cpu_active(cpu, true);
1924 set_cpu_present(cpu, true);
1925 set_cpu_possible(cpu, true);
1926}
1927
1928/*
1929 * Must be called _AFTER_ setting up the per_cpu areas
1930 */
1931void __init boot_cpu_state_init(void)
1932{
1933 per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
1934}