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/sched/smt.h>
14#include <linux/unistd.h>
15#include <linux/cpu.h>
16#include <linux/oom.h>
17#include <linux/rcupdate.h>
18#include <linux/export.h>
19#include <linux/bug.h>
20#include <linux/kthread.h>
21#include <linux/stop_machine.h>
22#include <linux/mutex.h>
23#include <linux/gfp.h>
24#include <linux/suspend.h>
25#include <linux/lockdep.h>
26#include <linux/tick.h>
27#include <linux/irq.h>
28#include <linux/nmi.h>
29#include <linux/smpboot.h>
30#include <linux/relay.h>
31#include <linux/slab.h>
32#include <linux/percpu-rwsem.h>
33
34#include <trace/events/power.h>
35#define CREATE_TRACE_POINTS
36#include <trace/events/cpuhp.h>
37
38#include "smpboot.h"
39
40/**
41 * cpuhp_cpu_state - Per cpu hotplug state storage
42 * @state: The current cpu state
43 * @target: The target state
44 * @thread: Pointer to the hotplug thread
45 * @should_run: Thread should execute
46 * @rollback: Perform a rollback
47 * @single: Single callback invocation
48 * @bringup: Single callback bringup or teardown selector
49 * @cb_state: The state for a single callback (install/uninstall)
50 * @result: Result of the operation
51 * @done_up: Signal completion to the issuer of the task for cpu-up
52 * @done_down: Signal completion to the issuer of the task for cpu-down
53 */
54struct cpuhp_cpu_state {
55 enum cpuhp_state state;
56 enum cpuhp_state target;
57 enum cpuhp_state fail;
58#ifdef CONFIG_SMP
59 struct task_struct *thread;
60 bool should_run;
61 bool rollback;
62 bool single;
63 bool bringup;
64 bool booted_once;
65 struct hlist_node *node;
66 struct hlist_node *last;
67 enum cpuhp_state cb_state;
68 int result;
69 struct completion done_up;
70 struct completion done_down;
71#endif
72};
73
74static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = {
75 .fail = CPUHP_INVALID,
76};
77
78#if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP)
79static struct lockdep_map cpuhp_state_up_map =
80 STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map);
81static struct lockdep_map cpuhp_state_down_map =
82 STATIC_LOCKDEP_MAP_INIT("cpuhp_state-down", &cpuhp_state_down_map);
83
84
85static inline void cpuhp_lock_acquire(bool bringup)
86{
87 lock_map_acquire(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map);
88}
89
90static inline void cpuhp_lock_release(bool bringup)
91{
92 lock_map_release(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map);
93}
94#else
95
96static inline void cpuhp_lock_acquire(bool bringup) { }
97static inline void cpuhp_lock_release(bool bringup) { }
98
99#endif
100
101/**
102 * cpuhp_step - Hotplug state machine step
103 * @name: Name of the step
104 * @startup: Startup function of the step
105 * @teardown: Teardown function of the step
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 cant_stop;
122 bool multi_instance;
123};
124
125static DEFINE_MUTEX(cpuhp_state_mutex);
126static struct cpuhp_step cpuhp_hp_states[];
127
128static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
129{
130 return cpuhp_hp_states + state;
131}
132
133/**
134 * cpuhp_invoke_callback _ Invoke the callbacks for a given state
135 * @cpu: The cpu for which the callback should be invoked
136 * @state: The state to do callbacks for
137 * @bringup: True if the bringup callback should be invoked
138 * @node: For multi-instance, do a single entry callback for install/remove
139 * @lastp: For multi-instance rollback, remember how far we got
140 *
141 * Called from cpu hotplug and from the state register machinery.
142 */
143static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
144 bool bringup, struct hlist_node *node,
145 struct hlist_node **lastp)
146{
147 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
148 struct cpuhp_step *step = cpuhp_get_step(state);
149 int (*cbm)(unsigned int cpu, struct hlist_node *node);
150 int (*cb)(unsigned int cpu);
151 int ret, cnt;
152
153 if (st->fail == state) {
154 st->fail = CPUHP_INVALID;
155
156 if (!(bringup ? step->startup.single : step->teardown.single))
157 return 0;
158
159 return -EAGAIN;
160 }
161
162 if (!step->multi_instance) {
163 WARN_ON_ONCE(lastp && *lastp);
164 cb = bringup ? step->startup.single : step->teardown.single;
165 if (!cb)
166 return 0;
167 trace_cpuhp_enter(cpu, st->target, state, cb);
168 ret = cb(cpu);
169 trace_cpuhp_exit(cpu, st->state, state, ret);
170 return ret;
171 }
172 cbm = bringup ? step->startup.multi : step->teardown.multi;
173 if (!cbm)
174 return 0;
175
176 /* Single invocation for instance add/remove */
177 if (node) {
178 WARN_ON_ONCE(lastp && *lastp);
179 trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
180 ret = cbm(cpu, node);
181 trace_cpuhp_exit(cpu, st->state, state, ret);
182 return ret;
183 }
184
185 /* State transition. Invoke on all instances */
186 cnt = 0;
187 hlist_for_each(node, &step->list) {
188 if (lastp && node == *lastp)
189 break;
190
191 trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
192 ret = cbm(cpu, node);
193 trace_cpuhp_exit(cpu, st->state, state, ret);
194 if (ret) {
195 if (!lastp)
196 goto err;
197
198 *lastp = node;
199 return ret;
200 }
201 cnt++;
202 }
203 if (lastp)
204 *lastp = NULL;
205 return 0;
206err:
207 /* Rollback the instances if one failed */
208 cbm = !bringup ? step->startup.multi : step->teardown.multi;
209 if (!cbm)
210 return ret;
211
212 hlist_for_each(node, &step->list) {
213 if (!cnt--)
214 break;
215
216 trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
217 ret = cbm(cpu, node);
218 trace_cpuhp_exit(cpu, st->state, state, ret);
219 /*
220 * Rollback must not fail,
221 */
222 WARN_ON_ONCE(ret);
223 }
224 return ret;
225}
226
227#ifdef CONFIG_SMP
228static bool cpuhp_is_ap_state(enum cpuhp_state state)
229{
230 /*
231 * The extra check for CPUHP_TEARDOWN_CPU is only for documentation
232 * purposes as that state is handled explicitly in cpu_down.
233 */
234 return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
235}
236
237static inline void wait_for_ap_thread(struct cpuhp_cpu_state *st, bool bringup)
238{
239 struct completion *done = bringup ? &st->done_up : &st->done_down;
240 wait_for_completion(done);
241}
242
243static inline void complete_ap_thread(struct cpuhp_cpu_state *st, bool bringup)
244{
245 struct completion *done = bringup ? &st->done_up : &st->done_down;
246 complete(done);
247}
248
249/*
250 * The former STARTING/DYING states, ran with IRQs disabled and must not fail.
251 */
252static bool cpuhp_is_atomic_state(enum cpuhp_state state)
253{
254 return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE;
255}
256
257/* Serializes the updates to cpu_online_mask, cpu_present_mask */
258static DEFINE_MUTEX(cpu_add_remove_lock);
259bool cpuhp_tasks_frozen;
260EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen);
261
262/*
263 * The following two APIs (cpu_maps_update_begin/done) must be used when
264 * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
265 */
266void cpu_maps_update_begin(void)
267{
268 mutex_lock(&cpu_add_remove_lock);
269}
270
271void cpu_maps_update_done(void)
272{
273 mutex_unlock(&cpu_add_remove_lock);
274}
275
276/*
277 * If set, cpu_up and cpu_down will return -EBUSY and do nothing.
278 * Should always be manipulated under cpu_add_remove_lock
279 */
280static int cpu_hotplug_disabled;
281
282#ifdef CONFIG_HOTPLUG_CPU
283
284DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock);
285
286void cpus_read_lock(void)
287{
288 percpu_down_read(&cpu_hotplug_lock);
289}
290EXPORT_SYMBOL_GPL(cpus_read_lock);
291
292int cpus_read_trylock(void)
293{
294 return percpu_down_read_trylock(&cpu_hotplug_lock);
295}
296EXPORT_SYMBOL_GPL(cpus_read_trylock);
297
298void cpus_read_unlock(void)
299{
300 percpu_up_read(&cpu_hotplug_lock);
301}
302EXPORT_SYMBOL_GPL(cpus_read_unlock);
303
304void cpus_write_lock(void)
305{
306 percpu_down_write(&cpu_hotplug_lock);
307}
308
309void cpus_write_unlock(void)
310{
311 percpu_up_write(&cpu_hotplug_lock);
312}
313
314void lockdep_assert_cpus_held(void)
315{
316 /*
317 * We can't have hotplug operations before userspace starts running,
318 * and some init codepaths will knowingly not take the hotplug lock.
319 * This is all valid, so mute lockdep until it makes sense to report
320 * unheld locks.
321 */
322 if (system_state < SYSTEM_RUNNING)
323 return;
324
325 percpu_rwsem_assert_held(&cpu_hotplug_lock);
326}
327
328static void lockdep_acquire_cpus_lock(void)
329{
330 rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_);
331}
332
333static void lockdep_release_cpus_lock(void)
334{
335 rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, 1, _THIS_IP_);
336}
337
338/*
339 * Wait for currently running CPU hotplug operations to complete (if any) and
340 * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
341 * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
342 * hotplug path before performing hotplug operations. So acquiring that lock
343 * guarantees mutual exclusion from any currently running hotplug operations.
344 */
345void cpu_hotplug_disable(void)
346{
347 cpu_maps_update_begin();
348 cpu_hotplug_disabled++;
349 cpu_maps_update_done();
350}
351EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
352
353static void __cpu_hotplug_enable(void)
354{
355 if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
356 return;
357 cpu_hotplug_disabled--;
358}
359
360void cpu_hotplug_enable(void)
361{
362 cpu_maps_update_begin();
363 __cpu_hotplug_enable();
364 cpu_maps_update_done();
365}
366EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
367
368#else
369
370static void lockdep_acquire_cpus_lock(void)
371{
372}
373
374static void lockdep_release_cpus_lock(void)
375{
376}
377
378#endif /* CONFIG_HOTPLUG_CPU */
379
380/*
381 * Architectures that need SMT-specific errata handling during SMT hotplug
382 * should override this.
383 */
384void __weak arch_smt_update(void) { }
385
386#ifdef CONFIG_HOTPLUG_SMT
387enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED;
388
389void __init cpu_smt_disable(bool force)
390{
391 if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
392 cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
393 return;
394
395 if (force) {
396 pr_info("SMT: Force disabled\n");
397 cpu_smt_control = CPU_SMT_FORCE_DISABLED;
398 } else {
399 pr_info("SMT: disabled\n");
400 cpu_smt_control = CPU_SMT_DISABLED;
401 }
402}
403
404/*
405 * The decision whether SMT is supported can only be done after the full
406 * CPU identification. Called from architecture code.
407 */
408void __init cpu_smt_check_topology(void)
409{
410 if (!topology_smt_supported())
411 cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
412}
413
414static int __init smt_cmdline_disable(char *str)
415{
416 cpu_smt_disable(str && !strcmp(str, "force"));
417 return 0;
418}
419early_param("nosmt", smt_cmdline_disable);
420
421static inline bool cpu_smt_allowed(unsigned int cpu)
422{
423 if (cpu_smt_control == CPU_SMT_ENABLED)
424 return true;
425
426 if (topology_is_primary_thread(cpu))
427 return true;
428
429 /*
430 * On x86 it's required to boot all logical CPUs at least once so
431 * that the init code can get a chance to set CR4.MCE on each
432 * CPU. Otherwise, a broadacasted MCE observing CR4.MCE=0b on any
433 * core will shutdown the machine.
434 */
435 return !per_cpu(cpuhp_state, cpu).booted_once;
436}
437#else
438static inline bool cpu_smt_allowed(unsigned int cpu) { return true; }
439#endif
440
441static inline enum cpuhp_state
442cpuhp_set_state(struct cpuhp_cpu_state *st, enum cpuhp_state target)
443{
444 enum cpuhp_state prev_state = st->state;
445
446 st->rollback = false;
447 st->last = NULL;
448
449 st->target = target;
450 st->single = false;
451 st->bringup = st->state < target;
452
453 return prev_state;
454}
455
456static inline void
457cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state)
458{
459 st->rollback = true;
460
461 /*
462 * If we have st->last we need to undo partial multi_instance of this
463 * state first. Otherwise start undo at the previous state.
464 */
465 if (!st->last) {
466 if (st->bringup)
467 st->state--;
468 else
469 st->state++;
470 }
471
472 st->target = prev_state;
473 st->bringup = !st->bringup;
474}
475
476/* Regular hotplug invocation of the AP hotplug thread */
477static void __cpuhp_kick_ap(struct cpuhp_cpu_state *st)
478{
479 if (!st->single && st->state == st->target)
480 return;
481
482 st->result = 0;
483 /*
484 * Make sure the above stores are visible before should_run becomes
485 * true. Paired with the mb() above in cpuhp_thread_fun()
486 */
487 smp_mb();
488 st->should_run = true;
489 wake_up_process(st->thread);
490 wait_for_ap_thread(st, st->bringup);
491}
492
493static int cpuhp_kick_ap(struct cpuhp_cpu_state *st, enum cpuhp_state target)
494{
495 enum cpuhp_state prev_state;
496 int ret;
497
498 prev_state = cpuhp_set_state(st, target);
499 __cpuhp_kick_ap(st);
500 if ((ret = st->result)) {
501 cpuhp_reset_state(st, prev_state);
502 __cpuhp_kick_ap(st);
503 }
504
505 return ret;
506}
507
508static int bringup_wait_for_ap(unsigned int cpu)
509{
510 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
511
512 /* Wait for the CPU to reach CPUHP_AP_ONLINE_IDLE */
513 wait_for_ap_thread(st, true);
514 if (WARN_ON_ONCE((!cpu_online(cpu))))
515 return -ECANCELED;
516
517 /* Unpark the stopper thread and the hotplug thread of the target cpu */
518 stop_machine_unpark(cpu);
519 kthread_unpark(st->thread);
520
521 /*
522 * SMT soft disabling on X86 requires to bring the CPU out of the
523 * BIOS 'wait for SIPI' state in order to set the CR4.MCE bit. The
524 * CPU marked itself as booted_once in cpu_notify_starting() so the
525 * cpu_smt_allowed() check will now return false if this is not the
526 * primary sibling.
527 */
528 if (!cpu_smt_allowed(cpu))
529 return -ECANCELED;
530
531 if (st->target <= CPUHP_AP_ONLINE_IDLE)
532 return 0;
533
534 return cpuhp_kick_ap(st, st->target);
535}
536
537static int bringup_cpu(unsigned int cpu)
538{
539 struct task_struct *idle = idle_thread_get(cpu);
540 int ret;
541
542 /*
543 * Some architectures have to walk the irq descriptors to
544 * setup the vector space for the cpu which comes online.
545 * Prevent irq alloc/free across the bringup.
546 */
547 irq_lock_sparse();
548
549 /* Arch-specific enabling code. */
550 ret = __cpu_up(cpu, idle);
551 irq_unlock_sparse();
552 if (ret)
553 return ret;
554 return bringup_wait_for_ap(cpu);
555}
556
557/*
558 * Hotplug state machine related functions
559 */
560
561static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st)
562{
563 for (st->state--; st->state > st->target; st->state--)
564 cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
565}
566
567static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
568 enum cpuhp_state target)
569{
570 enum cpuhp_state prev_state = st->state;
571 int ret = 0;
572
573 while (st->state < target) {
574 st->state++;
575 ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
576 if (ret) {
577 st->target = prev_state;
578 undo_cpu_up(cpu, st);
579 break;
580 }
581 }
582 return ret;
583}
584
585/*
586 * The cpu hotplug threads manage the bringup and teardown of the cpus
587 */
588static void cpuhp_create(unsigned int cpu)
589{
590 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
591
592 init_completion(&st->done_up);
593 init_completion(&st->done_down);
594}
595
596static int cpuhp_should_run(unsigned int cpu)
597{
598 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
599
600 return st->should_run;
601}
602
603/*
604 * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke
605 * callbacks when a state gets [un]installed at runtime.
606 *
607 * Each invocation of this function by the smpboot thread does a single AP
608 * state callback.
609 *
610 * It has 3 modes of operation:
611 * - single: runs st->cb_state
612 * - up: runs ++st->state, while st->state < st->target
613 * - down: runs st->state--, while st->state > st->target
614 *
615 * When complete or on error, should_run is cleared and the completion is fired.
616 */
617static void cpuhp_thread_fun(unsigned int cpu)
618{
619 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
620 bool bringup = st->bringup;
621 enum cpuhp_state state;
622
623 if (WARN_ON_ONCE(!st->should_run))
624 return;
625
626 /*
627 * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures
628 * that if we see ->should_run we also see the rest of the state.
629 */
630 smp_mb();
631
632 /*
633 * The BP holds the hotplug lock, but we're now running on the AP,
634 * ensure that anybody asserting the lock is held, will actually find
635 * it so.
636 */
637 lockdep_acquire_cpus_lock();
638 cpuhp_lock_acquire(bringup);
639
640 if (st->single) {
641 state = st->cb_state;
642 st->should_run = false;
643 } else {
644 if (bringup) {
645 st->state++;
646 state = st->state;
647 st->should_run = (st->state < st->target);
648 WARN_ON_ONCE(st->state > st->target);
649 } else {
650 state = st->state;
651 st->state--;
652 st->should_run = (st->state > st->target);
653 WARN_ON_ONCE(st->state < st->target);
654 }
655 }
656
657 WARN_ON_ONCE(!cpuhp_is_ap_state(state));
658
659 if (cpuhp_is_atomic_state(state)) {
660 local_irq_disable();
661 st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last);
662 local_irq_enable();
663
664 /*
665 * STARTING/DYING must not fail!
666 */
667 WARN_ON_ONCE(st->result);
668 } else {
669 st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last);
670 }
671
672 if (st->result) {
673 /*
674 * If we fail on a rollback, we're up a creek without no
675 * paddle, no way forward, no way back. We loose, thanks for
676 * playing.
677 */
678 WARN_ON_ONCE(st->rollback);
679 st->should_run = false;
680 }
681
682 cpuhp_lock_release(bringup);
683 lockdep_release_cpus_lock();
684
685 if (!st->should_run)
686 complete_ap_thread(st, bringup);
687}
688
689/* Invoke a single callback on a remote cpu */
690static int
691cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup,
692 struct hlist_node *node)
693{
694 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
695 int ret;
696
697 if (!cpu_online(cpu))
698 return 0;
699
700 cpuhp_lock_acquire(false);
701 cpuhp_lock_release(false);
702
703 cpuhp_lock_acquire(true);
704 cpuhp_lock_release(true);
705
706 /*
707 * If we are up and running, use the hotplug thread. For early calls
708 * we invoke the thread function directly.
709 */
710 if (!st->thread)
711 return cpuhp_invoke_callback(cpu, state, bringup, node, NULL);
712
713 st->rollback = false;
714 st->last = NULL;
715
716 st->node = node;
717 st->bringup = bringup;
718 st->cb_state = state;
719 st->single = true;
720
721 __cpuhp_kick_ap(st);
722
723 /*
724 * If we failed and did a partial, do a rollback.
725 */
726 if ((ret = st->result) && st->last) {
727 st->rollback = true;
728 st->bringup = !bringup;
729
730 __cpuhp_kick_ap(st);
731 }
732
733 /*
734 * Clean up the leftovers so the next hotplug operation wont use stale
735 * data.
736 */
737 st->node = st->last = NULL;
738 return ret;
739}
740
741static int cpuhp_kick_ap_work(unsigned int cpu)
742{
743 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
744 enum cpuhp_state prev_state = st->state;
745 int ret;
746
747 cpuhp_lock_acquire(false);
748 cpuhp_lock_release(false);
749
750 cpuhp_lock_acquire(true);
751 cpuhp_lock_release(true);
752
753 trace_cpuhp_enter(cpu, st->target, prev_state, cpuhp_kick_ap_work);
754 ret = cpuhp_kick_ap(st, st->target);
755 trace_cpuhp_exit(cpu, st->state, prev_state, ret);
756
757 return ret;
758}
759
760static struct smp_hotplug_thread cpuhp_threads = {
761 .store = &cpuhp_state.thread,
762 .create = &cpuhp_create,
763 .thread_should_run = cpuhp_should_run,
764 .thread_fn = cpuhp_thread_fun,
765 .thread_comm = "cpuhp/%u",
766 .selfparking = true,
767};
768
769void __init cpuhp_threads_init(void)
770{
771 BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads));
772 kthread_unpark(this_cpu_read(cpuhp_state.thread));
773}
774
775#ifdef CONFIG_HOTPLUG_CPU
776/**
777 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
778 * @cpu: a CPU id
779 *
780 * This function walks all processes, finds a valid mm struct for each one and
781 * then clears a corresponding bit in mm's cpumask. While this all sounds
782 * trivial, there are various non-obvious corner cases, which this function
783 * tries to solve in a safe manner.
784 *
785 * Also note that the function uses a somewhat relaxed locking scheme, so it may
786 * be called only for an already offlined CPU.
787 */
788void clear_tasks_mm_cpumask(int cpu)
789{
790 struct task_struct *p;
791
792 /*
793 * This function is called after the cpu is taken down and marked
794 * offline, so its not like new tasks will ever get this cpu set in
795 * their mm mask. -- Peter Zijlstra
796 * Thus, we may use rcu_read_lock() here, instead of grabbing
797 * full-fledged tasklist_lock.
798 */
799 WARN_ON(cpu_online(cpu));
800 rcu_read_lock();
801 for_each_process(p) {
802 struct task_struct *t;
803
804 /*
805 * Main thread might exit, but other threads may still have
806 * a valid mm. Find one.
807 */
808 t = find_lock_task_mm(p);
809 if (!t)
810 continue;
811 cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
812 task_unlock(t);
813 }
814 rcu_read_unlock();
815}
816
817/* Take this CPU down. */
818static int take_cpu_down(void *_param)
819{
820 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
821 enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE);
822 int err, cpu = smp_processor_id();
823 int ret;
824
825 /* Ensure this CPU doesn't handle any more interrupts. */
826 err = __cpu_disable();
827 if (err < 0)
828 return err;
829
830 /*
831 * We get here while we are in CPUHP_TEARDOWN_CPU state and we must not
832 * do this step again.
833 */
834 WARN_ON(st->state != CPUHP_TEARDOWN_CPU);
835 st->state--;
836 /* Invoke the former CPU_DYING callbacks */
837 for (; st->state > target; st->state--) {
838 ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
839 /*
840 * DYING must not fail!
841 */
842 WARN_ON_ONCE(ret);
843 }
844
845 /* Give up timekeeping duties */
846 tick_handover_do_timer();
847 /* Park the stopper thread */
848 stop_machine_park(cpu);
849 return 0;
850}
851
852static int takedown_cpu(unsigned int cpu)
853{
854 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
855 int err;
856
857 /* Park the smpboot threads */
858 kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread);
859
860 /*
861 * Prevent irq alloc/free while the dying cpu reorganizes the
862 * interrupt affinities.
863 */
864 irq_lock_sparse();
865
866 /*
867 * So now all preempt/rcu users must observe !cpu_active().
868 */
869 err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu));
870 if (err) {
871 /* CPU refused to die */
872 irq_unlock_sparse();
873 /* Unpark the hotplug thread so we can rollback there */
874 kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread);
875 return err;
876 }
877 BUG_ON(cpu_online(cpu));
878
879 /*
880 * The teardown callback for CPUHP_AP_SCHED_STARTING will have removed
881 * all runnable tasks from the CPU, there's only the idle task left now
882 * that the migration thread is done doing the stop_machine thing.
883 *
884 * Wait for the stop thread to go away.
885 */
886 wait_for_ap_thread(st, false);
887 BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
888
889 /* Interrupts are moved away from the dying cpu, reenable alloc/free */
890 irq_unlock_sparse();
891
892 hotplug_cpu__broadcast_tick_pull(cpu);
893 /* This actually kills the CPU. */
894 __cpu_die(cpu);
895
896 tick_cleanup_dead_cpu(cpu);
897 rcutree_migrate_callbacks(cpu);
898 return 0;
899}
900
901static void cpuhp_complete_idle_dead(void *arg)
902{
903 struct cpuhp_cpu_state *st = arg;
904
905 complete_ap_thread(st, false);
906}
907
908void cpuhp_report_idle_dead(void)
909{
910 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
911
912 BUG_ON(st->state != CPUHP_AP_OFFLINE);
913 rcu_report_dead(smp_processor_id());
914 st->state = CPUHP_AP_IDLE_DEAD;
915 /*
916 * We cannot call complete after rcu_report_dead() so we delegate it
917 * to an online cpu.
918 */
919 smp_call_function_single(cpumask_first(cpu_online_mask),
920 cpuhp_complete_idle_dead, st, 0);
921}
922
923static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st)
924{
925 for (st->state++; st->state < st->target; st->state++)
926 cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
927}
928
929static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
930 enum cpuhp_state target)
931{
932 enum cpuhp_state prev_state = st->state;
933 int ret = 0;
934
935 for (; st->state > target; st->state--) {
936 ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
937 if (ret) {
938 st->target = prev_state;
939 if (st->state < prev_state)
940 undo_cpu_down(cpu, st);
941 break;
942 }
943 }
944 return ret;
945}
946
947/* Requires cpu_add_remove_lock to be held */
948static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
949 enum cpuhp_state target)
950{
951 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
952 int prev_state, ret = 0;
953
954 if (num_online_cpus() == 1)
955 return -EBUSY;
956
957 if (!cpu_present(cpu))
958 return -EINVAL;
959
960 cpus_write_lock();
961
962 cpuhp_tasks_frozen = tasks_frozen;
963
964 prev_state = cpuhp_set_state(st, target);
965 /*
966 * If the current CPU state is in the range of the AP hotplug thread,
967 * then we need to kick the thread.
968 */
969 if (st->state > CPUHP_TEARDOWN_CPU) {
970 st->target = max((int)target, CPUHP_TEARDOWN_CPU);
971 ret = cpuhp_kick_ap_work(cpu);
972 /*
973 * The AP side has done the error rollback already. Just
974 * return the error code..
975 */
976 if (ret)
977 goto out;
978
979 /*
980 * We might have stopped still in the range of the AP hotplug
981 * thread. Nothing to do anymore.
982 */
983 if (st->state > CPUHP_TEARDOWN_CPU)
984 goto out;
985
986 st->target = target;
987 }
988 /*
989 * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need
990 * to do the further cleanups.
991 */
992 ret = cpuhp_down_callbacks(cpu, st, target);
993 if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) {
994 cpuhp_reset_state(st, prev_state);
995 __cpuhp_kick_ap(st);
996 }
997
998out:
999 cpus_write_unlock();
1000 /*
1001 * Do post unplug cleanup. This is still protected against
1002 * concurrent CPU hotplug via cpu_add_remove_lock.
1003 */
1004 lockup_detector_cleanup();
1005 arch_smt_update();
1006 return ret;
1007}
1008
1009static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target)
1010{
1011 if (cpu_hotplug_disabled)
1012 return -EBUSY;
1013 return _cpu_down(cpu, 0, target);
1014}
1015
1016static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
1017{
1018 int err;
1019
1020 cpu_maps_update_begin();
1021 err = cpu_down_maps_locked(cpu, target);
1022 cpu_maps_update_done();
1023 return err;
1024}
1025
1026int cpu_down(unsigned int cpu)
1027{
1028 return do_cpu_down(cpu, CPUHP_OFFLINE);
1029}
1030EXPORT_SYMBOL(cpu_down);
1031
1032#else
1033#define takedown_cpu NULL
1034#endif /*CONFIG_HOTPLUG_CPU*/
1035
1036/**
1037 * notify_cpu_starting(cpu) - Invoke the callbacks on the starting CPU
1038 * @cpu: cpu that just started
1039 *
1040 * It must be called by the arch code on the new cpu, before the new cpu
1041 * enables interrupts and before the "boot" cpu returns from __cpu_up().
1042 */
1043void notify_cpu_starting(unsigned int cpu)
1044{
1045 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1046 enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
1047 int ret;
1048
1049 rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */
1050 st->booted_once = true;
1051 while (st->state < target) {
1052 st->state++;
1053 ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
1054 /*
1055 * STARTING must not fail!
1056 */
1057 WARN_ON_ONCE(ret);
1058 }
1059}
1060
1061/*
1062 * Called from the idle task. Wake up the controlling task which brings the
1063 * stopper and the hotplug thread of the upcoming CPU up and then delegates
1064 * the rest of the online bringup to the hotplug thread.
1065 */
1066void cpuhp_online_idle(enum cpuhp_state state)
1067{
1068 struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
1069
1070 /* Happens for the boot cpu */
1071 if (state != CPUHP_AP_ONLINE_IDLE)
1072 return;
1073
1074 st->state = CPUHP_AP_ONLINE_IDLE;
1075 complete_ap_thread(st, true);
1076}
1077
1078/* Requires cpu_add_remove_lock to be held */
1079static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
1080{
1081 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1082 struct task_struct *idle;
1083 int ret = 0;
1084
1085 cpus_write_lock();
1086
1087 if (!cpu_present(cpu)) {
1088 ret = -EINVAL;
1089 goto out;
1090 }
1091
1092 /*
1093 * The caller of do_cpu_up might have raced with another
1094 * caller. Ignore it for now.
1095 */
1096 if (st->state >= target)
1097 goto out;
1098
1099 if (st->state == CPUHP_OFFLINE) {
1100 /* Let it fail before we try to bring the cpu up */
1101 idle = idle_thread_get(cpu);
1102 if (IS_ERR(idle)) {
1103 ret = PTR_ERR(idle);
1104 goto out;
1105 }
1106 }
1107
1108 cpuhp_tasks_frozen = tasks_frozen;
1109
1110 cpuhp_set_state(st, target);
1111 /*
1112 * If the current CPU state is in the range of the AP hotplug thread,
1113 * then we need to kick the thread once more.
1114 */
1115 if (st->state > CPUHP_BRINGUP_CPU) {
1116 ret = cpuhp_kick_ap_work(cpu);
1117 /*
1118 * The AP side has done the error rollback already. Just
1119 * return the error code..
1120 */
1121 if (ret)
1122 goto out;
1123 }
1124
1125 /*
1126 * Try to reach the target state. We max out on the BP at
1127 * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
1128 * responsible for bringing it up to the target state.
1129 */
1130 target = min((int)target, CPUHP_BRINGUP_CPU);
1131 ret = cpuhp_up_callbacks(cpu, st, target);
1132out:
1133 cpus_write_unlock();
1134 arch_smt_update();
1135 return ret;
1136}
1137
1138static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
1139{
1140 int err = 0;
1141
1142 if (!cpu_possible(cpu)) {
1143 pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
1144 cpu);
1145#if defined(CONFIG_IA64)
1146 pr_err("please check additional_cpus= boot parameter\n");
1147#endif
1148 return -EINVAL;
1149 }
1150
1151 err = try_online_node(cpu_to_node(cpu));
1152 if (err)
1153 return err;
1154
1155 cpu_maps_update_begin();
1156
1157 if (cpu_hotplug_disabled) {
1158 err = -EBUSY;
1159 goto out;
1160 }
1161 if (!cpu_smt_allowed(cpu)) {
1162 err = -EPERM;
1163 goto out;
1164 }
1165
1166 err = _cpu_up(cpu, 0, target);
1167out:
1168 cpu_maps_update_done();
1169 return err;
1170}
1171
1172int cpu_up(unsigned int cpu)
1173{
1174 return do_cpu_up(cpu, CPUHP_ONLINE);
1175}
1176EXPORT_SYMBOL_GPL(cpu_up);
1177
1178#ifdef CONFIG_PM_SLEEP_SMP
1179static cpumask_var_t frozen_cpus;
1180
1181int freeze_secondary_cpus(int primary)
1182{
1183 int cpu, error = 0;
1184
1185 cpu_maps_update_begin();
1186 if (!cpu_online(primary))
1187 primary = cpumask_first(cpu_online_mask);
1188 /*
1189 * We take down all of the non-boot CPUs in one shot to avoid races
1190 * with the userspace trying to use the CPU hotplug at the same time
1191 */
1192 cpumask_clear(frozen_cpus);
1193
1194 pr_info("Disabling non-boot CPUs ...\n");
1195 for_each_online_cpu(cpu) {
1196 if (cpu == primary)
1197 continue;
1198 trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
1199 error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
1200 trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
1201 if (!error)
1202 cpumask_set_cpu(cpu, frozen_cpus);
1203 else {
1204 pr_err("Error taking CPU%d down: %d\n", cpu, error);
1205 break;
1206 }
1207 }
1208
1209 if (!error)
1210 BUG_ON(num_online_cpus() > 1);
1211 else
1212 pr_err("Non-boot CPUs are not disabled\n");
1213
1214 /*
1215 * Make sure the CPUs won't be enabled by someone else. We need to do
1216 * this even in case of failure as all disable_nonboot_cpus() users are
1217 * supposed to do enable_nonboot_cpus() on the failure path.
1218 */
1219 cpu_hotplug_disabled++;
1220
1221 cpu_maps_update_done();
1222 return error;
1223}
1224
1225void __weak arch_enable_nonboot_cpus_begin(void)
1226{
1227}
1228
1229void __weak arch_enable_nonboot_cpus_end(void)
1230{
1231}
1232
1233void enable_nonboot_cpus(void)
1234{
1235 int cpu, error;
1236
1237 /* Allow everyone to use the CPU hotplug again */
1238 cpu_maps_update_begin();
1239 __cpu_hotplug_enable();
1240 if (cpumask_empty(frozen_cpus))
1241 goto out;
1242
1243 pr_info("Enabling non-boot CPUs ...\n");
1244
1245 arch_enable_nonboot_cpus_begin();
1246
1247 for_each_cpu(cpu, frozen_cpus) {
1248 trace_suspend_resume(TPS("CPU_ON"), cpu, true);
1249 error = _cpu_up(cpu, 1, CPUHP_ONLINE);
1250 trace_suspend_resume(TPS("CPU_ON"), cpu, false);
1251 if (!error) {
1252 pr_info("CPU%d is up\n", cpu);
1253 continue;
1254 }
1255 pr_warn("Error taking CPU%d up: %d\n", cpu, error);
1256 }
1257
1258 arch_enable_nonboot_cpus_end();
1259
1260 cpumask_clear(frozen_cpus);
1261out:
1262 cpu_maps_update_done();
1263}
1264
1265static int __init alloc_frozen_cpus(void)
1266{
1267 if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
1268 return -ENOMEM;
1269 return 0;
1270}
1271core_initcall(alloc_frozen_cpus);
1272
1273/*
1274 * When callbacks for CPU hotplug notifications are being executed, we must
1275 * ensure that the state of the system with respect to the tasks being frozen
1276 * or not, as reported by the notification, remains unchanged *throughout the
1277 * duration* of the execution of the callbacks.
1278 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
1279 *
1280 * This synchronization is implemented by mutually excluding regular CPU
1281 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
1282 * Hibernate notifications.
1283 */
1284static int
1285cpu_hotplug_pm_callback(struct notifier_block *nb,
1286 unsigned long action, void *ptr)
1287{
1288 switch (action) {
1289
1290 case PM_SUSPEND_PREPARE:
1291 case PM_HIBERNATION_PREPARE:
1292 cpu_hotplug_disable();
1293 break;
1294
1295 case PM_POST_SUSPEND:
1296 case PM_POST_HIBERNATION:
1297 cpu_hotplug_enable();
1298 break;
1299
1300 default:
1301 return NOTIFY_DONE;
1302 }
1303
1304 return NOTIFY_OK;
1305}
1306
1307
1308static int __init cpu_hotplug_pm_sync_init(void)
1309{
1310 /*
1311 * cpu_hotplug_pm_callback has higher priority than x86
1312 * bsp_pm_callback which depends on cpu_hotplug_pm_callback
1313 * to disable cpu hotplug to avoid cpu hotplug race.
1314 */
1315 pm_notifier(cpu_hotplug_pm_callback, 0);
1316 return 0;
1317}
1318core_initcall(cpu_hotplug_pm_sync_init);
1319
1320#endif /* CONFIG_PM_SLEEP_SMP */
1321
1322int __boot_cpu_id;
1323
1324#endif /* CONFIG_SMP */
1325
1326/* Boot processor state steps */
1327static struct cpuhp_step cpuhp_hp_states[] = {
1328 [CPUHP_OFFLINE] = {
1329 .name = "offline",
1330 .startup.single = NULL,
1331 .teardown.single = NULL,
1332 },
1333#ifdef CONFIG_SMP
1334 [CPUHP_CREATE_THREADS]= {
1335 .name = "threads:prepare",
1336 .startup.single = smpboot_create_threads,
1337 .teardown.single = NULL,
1338 .cant_stop = true,
1339 },
1340 [CPUHP_PERF_PREPARE] = {
1341 .name = "perf:prepare",
1342 .startup.single = perf_event_init_cpu,
1343 .teardown.single = perf_event_exit_cpu,
1344 },
1345 [CPUHP_WORKQUEUE_PREP] = {
1346 .name = "workqueue:prepare",
1347 .startup.single = workqueue_prepare_cpu,
1348 .teardown.single = NULL,
1349 },
1350 [CPUHP_HRTIMERS_PREPARE] = {
1351 .name = "hrtimers:prepare",
1352 .startup.single = hrtimers_prepare_cpu,
1353 .teardown.single = hrtimers_dead_cpu,
1354 },
1355 [CPUHP_SMPCFD_PREPARE] = {
1356 .name = "smpcfd:prepare",
1357 .startup.single = smpcfd_prepare_cpu,
1358 .teardown.single = smpcfd_dead_cpu,
1359 },
1360 [CPUHP_RELAY_PREPARE] = {
1361 .name = "relay:prepare",
1362 .startup.single = relay_prepare_cpu,
1363 .teardown.single = NULL,
1364 },
1365 [CPUHP_SLAB_PREPARE] = {
1366 .name = "slab:prepare",
1367 .startup.single = slab_prepare_cpu,
1368 .teardown.single = slab_dead_cpu,
1369 },
1370 [CPUHP_RCUTREE_PREP] = {
1371 .name = "RCU/tree:prepare",
1372 .startup.single = rcutree_prepare_cpu,
1373 .teardown.single = rcutree_dead_cpu,
1374 },
1375 /*
1376 * On the tear-down path, timers_dead_cpu() must be invoked
1377 * before blk_mq_queue_reinit_notify() from notify_dead(),
1378 * otherwise a RCU stall occurs.
1379 */
1380 [CPUHP_TIMERS_PREPARE] = {
1381 .name = "timers:prepare",
1382 .startup.single = timers_prepare_cpu,
1383 .teardown.single = timers_dead_cpu,
1384 },
1385 /* Kicks the plugged cpu into life */
1386 [CPUHP_BRINGUP_CPU] = {
1387 .name = "cpu:bringup",
1388 .startup.single = bringup_cpu,
1389 .teardown.single = NULL,
1390 .cant_stop = true,
1391 },
1392 /* Final state before CPU kills itself */
1393 [CPUHP_AP_IDLE_DEAD] = {
1394 .name = "idle:dead",
1395 },
1396 /*
1397 * Last state before CPU enters the idle loop to die. Transient state
1398 * for synchronization.
1399 */
1400 [CPUHP_AP_OFFLINE] = {
1401 .name = "ap:offline",
1402 .cant_stop = true,
1403 },
1404 /* First state is scheduler control. Interrupts are disabled */
1405 [CPUHP_AP_SCHED_STARTING] = {
1406 .name = "sched:starting",
1407 .startup.single = sched_cpu_starting,
1408 .teardown.single = sched_cpu_dying,
1409 },
1410 [CPUHP_AP_RCUTREE_DYING] = {
1411 .name = "RCU/tree:dying",
1412 .startup.single = NULL,
1413 .teardown.single = rcutree_dying_cpu,
1414 },
1415 [CPUHP_AP_SMPCFD_DYING] = {
1416 .name = "smpcfd:dying",
1417 .startup.single = NULL,
1418 .teardown.single = smpcfd_dying_cpu,
1419 },
1420 /* Entry state on starting. Interrupts enabled from here on. Transient
1421 * state for synchronsization */
1422 [CPUHP_AP_ONLINE] = {
1423 .name = "ap:online",
1424 },
1425 /*
1426 * Handled on controll processor until the plugged processor manages
1427 * this itself.
1428 */
1429 [CPUHP_TEARDOWN_CPU] = {
1430 .name = "cpu:teardown",
1431 .startup.single = NULL,
1432 .teardown.single = takedown_cpu,
1433 .cant_stop = true,
1434 },
1435 /* Handle smpboot threads park/unpark */
1436 [CPUHP_AP_SMPBOOT_THREADS] = {
1437 .name = "smpboot/threads:online",
1438 .startup.single = smpboot_unpark_threads,
1439 .teardown.single = smpboot_park_threads,
1440 },
1441 [CPUHP_AP_IRQ_AFFINITY_ONLINE] = {
1442 .name = "irq/affinity:online",
1443 .startup.single = irq_affinity_online_cpu,
1444 .teardown.single = NULL,
1445 },
1446 [CPUHP_AP_PERF_ONLINE] = {
1447 .name = "perf:online",
1448 .startup.single = perf_event_init_cpu,
1449 .teardown.single = perf_event_exit_cpu,
1450 },
1451 [CPUHP_AP_WATCHDOG_ONLINE] = {
1452 .name = "lockup_detector:online",
1453 .startup.single = lockup_detector_online_cpu,
1454 .teardown.single = lockup_detector_offline_cpu,
1455 },
1456 [CPUHP_AP_WORKQUEUE_ONLINE] = {
1457 .name = "workqueue:online",
1458 .startup.single = workqueue_online_cpu,
1459 .teardown.single = workqueue_offline_cpu,
1460 },
1461 [CPUHP_AP_RCUTREE_ONLINE] = {
1462 .name = "RCU/tree:online",
1463 .startup.single = rcutree_online_cpu,
1464 .teardown.single = rcutree_offline_cpu,
1465 },
1466#endif
1467 /*
1468 * The dynamically registered state space is here
1469 */
1470
1471#ifdef CONFIG_SMP
1472 /* Last state is scheduler control setting the cpu active */
1473 [CPUHP_AP_ACTIVE] = {
1474 .name = "sched:active",
1475 .startup.single = sched_cpu_activate,
1476 .teardown.single = sched_cpu_deactivate,
1477 },
1478#endif
1479
1480 /* CPU is fully up and running. */
1481 [CPUHP_ONLINE] = {
1482 .name = "online",
1483 .startup.single = NULL,
1484 .teardown.single = NULL,
1485 },
1486};
1487
1488/* Sanity check for callbacks */
1489static int cpuhp_cb_check(enum cpuhp_state state)
1490{
1491 if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
1492 return -EINVAL;
1493 return 0;
1494}
1495
1496/*
1497 * Returns a free for dynamic slot assignment of the Online state. The states
1498 * are protected by the cpuhp_slot_states mutex and an empty slot is identified
1499 * by having no name assigned.
1500 */
1501static int cpuhp_reserve_state(enum cpuhp_state state)
1502{
1503 enum cpuhp_state i, end;
1504 struct cpuhp_step *step;
1505
1506 switch (state) {
1507 case CPUHP_AP_ONLINE_DYN:
1508 step = cpuhp_hp_states + CPUHP_AP_ONLINE_DYN;
1509 end = CPUHP_AP_ONLINE_DYN_END;
1510 break;
1511 case CPUHP_BP_PREPARE_DYN:
1512 step = cpuhp_hp_states + CPUHP_BP_PREPARE_DYN;
1513 end = CPUHP_BP_PREPARE_DYN_END;
1514 break;
1515 default:
1516 return -EINVAL;
1517 }
1518
1519 for (i = state; i <= end; i++, step++) {
1520 if (!step->name)
1521 return i;
1522 }
1523 WARN(1, "No more dynamic states available for CPU hotplug\n");
1524 return -ENOSPC;
1525}
1526
1527static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name,
1528 int (*startup)(unsigned int cpu),
1529 int (*teardown)(unsigned int cpu),
1530 bool multi_instance)
1531{
1532 /* (Un)Install the callbacks for further cpu hotplug operations */
1533 struct cpuhp_step *sp;
1534 int ret = 0;
1535
1536 /*
1537 * If name is NULL, then the state gets removed.
1538 *
1539 * CPUHP_AP_ONLINE_DYN and CPUHP_BP_PREPARE_DYN are handed out on
1540 * the first allocation from these dynamic ranges, so the removal
1541 * would trigger a new allocation and clear the wrong (already
1542 * empty) state, leaving the callbacks of the to be cleared state
1543 * dangling, which causes wreckage on the next hotplug operation.
1544 */
1545 if (name && (state == CPUHP_AP_ONLINE_DYN ||
1546 state == CPUHP_BP_PREPARE_DYN)) {
1547 ret = cpuhp_reserve_state(state);
1548 if (ret < 0)
1549 return ret;
1550 state = ret;
1551 }
1552 sp = cpuhp_get_step(state);
1553 if (name && sp->name)
1554 return -EBUSY;
1555
1556 sp->startup.single = startup;
1557 sp->teardown.single = teardown;
1558 sp->name = name;
1559 sp->multi_instance = multi_instance;
1560 INIT_HLIST_HEAD(&sp->list);
1561 return ret;
1562}
1563
1564static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
1565{
1566 return cpuhp_get_step(state)->teardown.single;
1567}
1568
1569/*
1570 * Call the startup/teardown function for a step either on the AP or
1571 * on the current CPU.
1572 */
1573static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup,
1574 struct hlist_node *node)
1575{
1576 struct cpuhp_step *sp = cpuhp_get_step(state);
1577 int ret;
1578
1579 /*
1580 * If there's nothing to do, we done.
1581 * Relies on the union for multi_instance.
1582 */
1583 if ((bringup && !sp->startup.single) ||
1584 (!bringup && !sp->teardown.single))
1585 return 0;
1586 /*
1587 * The non AP bound callbacks can fail on bringup. On teardown
1588 * e.g. module removal we crash for now.
1589 */
1590#ifdef CONFIG_SMP
1591 if (cpuhp_is_ap_state(state))
1592 ret = cpuhp_invoke_ap_callback(cpu, state, bringup, node);
1593 else
1594 ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL);
1595#else
1596 ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL);
1597#endif
1598 BUG_ON(ret && !bringup);
1599 return ret;
1600}
1601
1602/*
1603 * Called from __cpuhp_setup_state on a recoverable failure.
1604 *
1605 * Note: The teardown callbacks for rollback are not allowed to fail!
1606 */
1607static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
1608 struct hlist_node *node)
1609{
1610 int cpu;
1611
1612 /* Roll back the already executed steps on the other cpus */
1613 for_each_present_cpu(cpu) {
1614 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1615 int cpustate = st->state;
1616
1617 if (cpu >= failedcpu)
1618 break;
1619
1620 /* Did we invoke the startup call on that cpu ? */
1621 if (cpustate >= state)
1622 cpuhp_issue_call(cpu, state, false, node);
1623 }
1624}
1625
1626int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state,
1627 struct hlist_node *node,
1628 bool invoke)
1629{
1630 struct cpuhp_step *sp;
1631 int cpu;
1632 int ret;
1633
1634 lockdep_assert_cpus_held();
1635
1636 sp = cpuhp_get_step(state);
1637 if (sp->multi_instance == false)
1638 return -EINVAL;
1639
1640 mutex_lock(&cpuhp_state_mutex);
1641
1642 if (!invoke || !sp->startup.multi)
1643 goto add_node;
1644
1645 /*
1646 * Try to call the startup callback for each present cpu
1647 * depending on the hotplug state of the cpu.
1648 */
1649 for_each_present_cpu(cpu) {
1650 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1651 int cpustate = st->state;
1652
1653 if (cpustate < state)
1654 continue;
1655
1656 ret = cpuhp_issue_call(cpu, state, true, node);
1657 if (ret) {
1658 if (sp->teardown.multi)
1659 cpuhp_rollback_install(cpu, state, node);
1660 goto unlock;
1661 }
1662 }
1663add_node:
1664 ret = 0;
1665 hlist_add_head(node, &sp->list);
1666unlock:
1667 mutex_unlock(&cpuhp_state_mutex);
1668 return ret;
1669}
1670
1671int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
1672 bool invoke)
1673{
1674 int ret;
1675
1676 cpus_read_lock();
1677 ret = __cpuhp_state_add_instance_cpuslocked(state, node, invoke);
1678 cpus_read_unlock();
1679 return ret;
1680}
1681EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
1682
1683/**
1684 * __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state
1685 * @state: The state to setup
1686 * @invoke: If true, the startup function is invoked for cpus where
1687 * cpu state >= @state
1688 * @startup: startup callback function
1689 * @teardown: teardown callback function
1690 * @multi_instance: State is set up for multiple instances which get
1691 * added afterwards.
1692 *
1693 * The caller needs to hold cpus read locked while calling this function.
1694 * Returns:
1695 * On success:
1696 * Positive state number if @state is CPUHP_AP_ONLINE_DYN
1697 * 0 for all other states
1698 * On failure: proper (negative) error code
1699 */
1700int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state,
1701 const char *name, bool invoke,
1702 int (*startup)(unsigned int cpu),
1703 int (*teardown)(unsigned int cpu),
1704 bool multi_instance)
1705{
1706 int cpu, ret = 0;
1707 bool dynstate;
1708
1709 lockdep_assert_cpus_held();
1710
1711 if (cpuhp_cb_check(state) || !name)
1712 return -EINVAL;
1713
1714 mutex_lock(&cpuhp_state_mutex);
1715
1716 ret = cpuhp_store_callbacks(state, name, startup, teardown,
1717 multi_instance);
1718
1719 dynstate = state == CPUHP_AP_ONLINE_DYN;
1720 if (ret > 0 && dynstate) {
1721 state = ret;
1722 ret = 0;
1723 }
1724
1725 if (ret || !invoke || !startup)
1726 goto out;
1727
1728 /*
1729 * Try to call the startup callback for each present cpu
1730 * depending on the hotplug state of the cpu.
1731 */
1732 for_each_present_cpu(cpu) {
1733 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1734 int cpustate = st->state;
1735
1736 if (cpustate < state)
1737 continue;
1738
1739 ret = cpuhp_issue_call(cpu, state, true, NULL);
1740 if (ret) {
1741 if (teardown)
1742 cpuhp_rollback_install(cpu, state, NULL);
1743 cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
1744 goto out;
1745 }
1746 }
1747out:
1748 mutex_unlock(&cpuhp_state_mutex);
1749 /*
1750 * If the requested state is CPUHP_AP_ONLINE_DYN, return the
1751 * dynamically allocated state in case of success.
1752 */
1753 if (!ret && dynstate)
1754 return state;
1755 return ret;
1756}
1757EXPORT_SYMBOL(__cpuhp_setup_state_cpuslocked);
1758
1759int __cpuhp_setup_state(enum cpuhp_state state,
1760 const char *name, bool invoke,
1761 int (*startup)(unsigned int cpu),
1762 int (*teardown)(unsigned int cpu),
1763 bool multi_instance)
1764{
1765 int ret;
1766
1767 cpus_read_lock();
1768 ret = __cpuhp_setup_state_cpuslocked(state, name, invoke, startup,
1769 teardown, multi_instance);
1770 cpus_read_unlock();
1771 return ret;
1772}
1773EXPORT_SYMBOL(__cpuhp_setup_state);
1774
1775int __cpuhp_state_remove_instance(enum cpuhp_state state,
1776 struct hlist_node *node, bool invoke)
1777{
1778 struct cpuhp_step *sp = cpuhp_get_step(state);
1779 int cpu;
1780
1781 BUG_ON(cpuhp_cb_check(state));
1782
1783 if (!sp->multi_instance)
1784 return -EINVAL;
1785
1786 cpus_read_lock();
1787 mutex_lock(&cpuhp_state_mutex);
1788
1789 if (!invoke || !cpuhp_get_teardown_cb(state))
1790 goto remove;
1791 /*
1792 * Call the teardown callback for each present cpu depending
1793 * on the hotplug state of the cpu. This function is not
1794 * allowed to fail currently!
1795 */
1796 for_each_present_cpu(cpu) {
1797 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1798 int cpustate = st->state;
1799
1800 if (cpustate >= state)
1801 cpuhp_issue_call(cpu, state, false, node);
1802 }
1803
1804remove:
1805 hlist_del(node);
1806 mutex_unlock(&cpuhp_state_mutex);
1807 cpus_read_unlock();
1808
1809 return 0;
1810}
1811EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance);
1812
1813/**
1814 * __cpuhp_remove_state_cpuslocked - Remove the callbacks for an hotplug machine state
1815 * @state: The state to remove
1816 * @invoke: If true, the teardown function is invoked for cpus where
1817 * cpu state >= @state
1818 *
1819 * The caller needs to hold cpus read locked while calling this function.
1820 * The teardown callback is currently not allowed to fail. Think
1821 * about module removal!
1822 */
1823void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke)
1824{
1825 struct cpuhp_step *sp = cpuhp_get_step(state);
1826 int cpu;
1827
1828 BUG_ON(cpuhp_cb_check(state));
1829
1830 lockdep_assert_cpus_held();
1831
1832 mutex_lock(&cpuhp_state_mutex);
1833 if (sp->multi_instance) {
1834 WARN(!hlist_empty(&sp->list),
1835 "Error: Removing state %d which has instances left.\n",
1836 state);
1837 goto remove;
1838 }
1839
1840 if (!invoke || !cpuhp_get_teardown_cb(state))
1841 goto remove;
1842
1843 /*
1844 * Call the teardown callback for each present cpu depending
1845 * on the hotplug state of the cpu. This function is not
1846 * allowed to fail currently!
1847 */
1848 for_each_present_cpu(cpu) {
1849 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1850 int cpustate = st->state;
1851
1852 if (cpustate >= state)
1853 cpuhp_issue_call(cpu, state, false, NULL);
1854 }
1855remove:
1856 cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
1857 mutex_unlock(&cpuhp_state_mutex);
1858}
1859EXPORT_SYMBOL(__cpuhp_remove_state_cpuslocked);
1860
1861void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
1862{
1863 cpus_read_lock();
1864 __cpuhp_remove_state_cpuslocked(state, invoke);
1865 cpus_read_unlock();
1866}
1867EXPORT_SYMBOL(__cpuhp_remove_state);
1868
1869#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
1870static ssize_t show_cpuhp_state(struct device *dev,
1871 struct device_attribute *attr, char *buf)
1872{
1873 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1874
1875 return sprintf(buf, "%d\n", st->state);
1876}
1877static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
1878
1879static ssize_t write_cpuhp_target(struct device *dev,
1880 struct device_attribute *attr,
1881 const char *buf, size_t count)
1882{
1883 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1884 struct cpuhp_step *sp;
1885 int target, ret;
1886
1887 ret = kstrtoint(buf, 10, &target);
1888 if (ret)
1889 return ret;
1890
1891#ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
1892 if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
1893 return -EINVAL;
1894#else
1895 if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
1896 return -EINVAL;
1897#endif
1898
1899 ret = lock_device_hotplug_sysfs();
1900 if (ret)
1901 return ret;
1902
1903 mutex_lock(&cpuhp_state_mutex);
1904 sp = cpuhp_get_step(target);
1905 ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
1906 mutex_unlock(&cpuhp_state_mutex);
1907 if (ret)
1908 goto out;
1909
1910 if (st->state < target)
1911 ret = do_cpu_up(dev->id, target);
1912 else
1913 ret = do_cpu_down(dev->id, target);
1914out:
1915 unlock_device_hotplug();
1916 return ret ? ret : count;
1917}
1918
1919static ssize_t show_cpuhp_target(struct device *dev,
1920 struct device_attribute *attr, char *buf)
1921{
1922 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1923
1924 return sprintf(buf, "%d\n", st->target);
1925}
1926static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
1927
1928
1929static ssize_t write_cpuhp_fail(struct device *dev,
1930 struct device_attribute *attr,
1931 const char *buf, size_t count)
1932{
1933 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1934 struct cpuhp_step *sp;
1935 int fail, ret;
1936
1937 ret = kstrtoint(buf, 10, &fail);
1938 if (ret)
1939 return ret;
1940
1941 /*
1942 * Cannot fail STARTING/DYING callbacks.
1943 */
1944 if (cpuhp_is_atomic_state(fail))
1945 return -EINVAL;
1946
1947 /*
1948 * Cannot fail anything that doesn't have callbacks.
1949 */
1950 mutex_lock(&cpuhp_state_mutex);
1951 sp = cpuhp_get_step(fail);
1952 if (!sp->startup.single && !sp->teardown.single)
1953 ret = -EINVAL;
1954 mutex_unlock(&cpuhp_state_mutex);
1955 if (ret)
1956 return ret;
1957
1958 st->fail = fail;
1959
1960 return count;
1961}
1962
1963static ssize_t show_cpuhp_fail(struct device *dev,
1964 struct device_attribute *attr, char *buf)
1965{
1966 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1967
1968 return sprintf(buf, "%d\n", st->fail);
1969}
1970
1971static DEVICE_ATTR(fail, 0644, show_cpuhp_fail, write_cpuhp_fail);
1972
1973static struct attribute *cpuhp_cpu_attrs[] = {
1974 &dev_attr_state.attr,
1975 &dev_attr_target.attr,
1976 &dev_attr_fail.attr,
1977 NULL
1978};
1979
1980static const struct attribute_group cpuhp_cpu_attr_group = {
1981 .attrs = cpuhp_cpu_attrs,
1982 .name = "hotplug",
1983 NULL
1984};
1985
1986static ssize_t show_cpuhp_states(struct device *dev,
1987 struct device_attribute *attr, char *buf)
1988{
1989 ssize_t cur, res = 0;
1990 int i;
1991
1992 mutex_lock(&cpuhp_state_mutex);
1993 for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
1994 struct cpuhp_step *sp = cpuhp_get_step(i);
1995
1996 if (sp->name) {
1997 cur = sprintf(buf, "%3d: %s\n", i, sp->name);
1998 buf += cur;
1999 res += cur;
2000 }
2001 }
2002 mutex_unlock(&cpuhp_state_mutex);
2003 return res;
2004}
2005static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);
2006
2007static struct attribute *cpuhp_cpu_root_attrs[] = {
2008 &dev_attr_states.attr,
2009 NULL
2010};
2011
2012static const struct attribute_group cpuhp_cpu_root_attr_group = {
2013 .attrs = cpuhp_cpu_root_attrs,
2014 .name = "hotplug",
2015 NULL
2016};
2017
2018#ifdef CONFIG_HOTPLUG_SMT
2019
2020static const char *smt_states[] = {
2021 [CPU_SMT_ENABLED] = "on",
2022 [CPU_SMT_DISABLED] = "off",
2023 [CPU_SMT_FORCE_DISABLED] = "forceoff",
2024 [CPU_SMT_NOT_SUPPORTED] = "notsupported",
2025};
2026
2027static ssize_t
2028show_smt_control(struct device *dev, struct device_attribute *attr, char *buf)
2029{
2030 return snprintf(buf, PAGE_SIZE - 2, "%s\n", smt_states[cpu_smt_control]);
2031}
2032
2033static void cpuhp_offline_cpu_device(unsigned int cpu)
2034{
2035 struct device *dev = get_cpu_device(cpu);
2036
2037 dev->offline = true;
2038 /* Tell user space about the state change */
2039 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
2040}
2041
2042static void cpuhp_online_cpu_device(unsigned int cpu)
2043{
2044 struct device *dev = get_cpu_device(cpu);
2045
2046 dev->offline = false;
2047 /* Tell user space about the state change */
2048 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
2049}
2050
2051static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
2052{
2053 int cpu, ret = 0;
2054
2055 cpu_maps_update_begin();
2056 for_each_online_cpu(cpu) {
2057 if (topology_is_primary_thread(cpu))
2058 continue;
2059 ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
2060 if (ret)
2061 break;
2062 /*
2063 * As this needs to hold the cpu maps lock it's impossible
2064 * to call device_offline() because that ends up calling
2065 * cpu_down() which takes cpu maps lock. cpu maps lock
2066 * needs to be held as this might race against in kernel
2067 * abusers of the hotplug machinery (thermal management).
2068 *
2069 * So nothing would update device:offline state. That would
2070 * leave the sysfs entry stale and prevent onlining after
2071 * smt control has been changed to 'off' again. This is
2072 * called under the sysfs hotplug lock, so it is properly
2073 * serialized against the regular offline usage.
2074 */
2075 cpuhp_offline_cpu_device(cpu);
2076 }
2077 if (!ret)
2078 cpu_smt_control = ctrlval;
2079 cpu_maps_update_done();
2080 return ret;
2081}
2082
2083static int cpuhp_smt_enable(void)
2084{
2085 int cpu, ret = 0;
2086
2087 cpu_maps_update_begin();
2088 cpu_smt_control = CPU_SMT_ENABLED;
2089 for_each_present_cpu(cpu) {
2090 /* Skip online CPUs and CPUs on offline nodes */
2091 if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
2092 continue;
2093 ret = _cpu_up(cpu, 0, CPUHP_ONLINE);
2094 if (ret)
2095 break;
2096 /* See comment in cpuhp_smt_disable() */
2097 cpuhp_online_cpu_device(cpu);
2098 }
2099 cpu_maps_update_done();
2100 return ret;
2101}
2102
2103static ssize_t
2104store_smt_control(struct device *dev, struct device_attribute *attr,
2105 const char *buf, size_t count)
2106{
2107 int ctrlval, ret;
2108
2109 if (sysfs_streq(buf, "on"))
2110 ctrlval = CPU_SMT_ENABLED;
2111 else if (sysfs_streq(buf, "off"))
2112 ctrlval = CPU_SMT_DISABLED;
2113 else if (sysfs_streq(buf, "forceoff"))
2114 ctrlval = CPU_SMT_FORCE_DISABLED;
2115 else
2116 return -EINVAL;
2117
2118 if (cpu_smt_control == CPU_SMT_FORCE_DISABLED)
2119 return -EPERM;
2120
2121 if (cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
2122 return -ENODEV;
2123
2124 ret = lock_device_hotplug_sysfs();
2125 if (ret)
2126 return ret;
2127
2128 if (ctrlval != cpu_smt_control) {
2129 switch (ctrlval) {
2130 case CPU_SMT_ENABLED:
2131 ret = cpuhp_smt_enable();
2132 break;
2133 case CPU_SMT_DISABLED:
2134 case CPU_SMT_FORCE_DISABLED:
2135 ret = cpuhp_smt_disable(ctrlval);
2136 break;
2137 }
2138 }
2139
2140 unlock_device_hotplug();
2141 return ret ? ret : count;
2142}
2143static DEVICE_ATTR(control, 0644, show_smt_control, store_smt_control);
2144
2145static ssize_t
2146show_smt_active(struct device *dev, struct device_attribute *attr, char *buf)
2147{
2148 bool active = topology_max_smt_threads() > 1;
2149
2150 return snprintf(buf, PAGE_SIZE - 2, "%d\n", active);
2151}
2152static DEVICE_ATTR(active, 0444, show_smt_active, NULL);
2153
2154static struct attribute *cpuhp_smt_attrs[] = {
2155 &dev_attr_control.attr,
2156 &dev_attr_active.attr,
2157 NULL
2158};
2159
2160static const struct attribute_group cpuhp_smt_attr_group = {
2161 .attrs = cpuhp_smt_attrs,
2162 .name = "smt",
2163 NULL
2164};
2165
2166static int __init cpu_smt_state_init(void)
2167{
2168 return sysfs_create_group(&cpu_subsys.dev_root->kobj,
2169 &cpuhp_smt_attr_group);
2170}
2171
2172#else
2173static inline int cpu_smt_state_init(void) { return 0; }
2174#endif
2175
2176static int __init cpuhp_sysfs_init(void)
2177{
2178 int cpu, ret;
2179
2180 ret = cpu_smt_state_init();
2181 if (ret)
2182 return ret;
2183
2184 ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
2185 &cpuhp_cpu_root_attr_group);
2186 if (ret)
2187 return ret;
2188
2189 for_each_possible_cpu(cpu) {
2190 struct device *dev = get_cpu_device(cpu);
2191
2192 if (!dev)
2193 continue;
2194 ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);
2195 if (ret)
2196 return ret;
2197 }
2198 return 0;
2199}
2200device_initcall(cpuhp_sysfs_init);
2201#endif
2202
2203/*
2204 * cpu_bit_bitmap[] is a special, "compressed" data structure that
2205 * represents all NR_CPUS bits binary values of 1<<nr.
2206 *
2207 * It is used by cpumask_of() to get a constant address to a CPU
2208 * mask value that has a single bit set only.
2209 */
2210
2211/* cpu_bit_bitmap[0] is empty - so we can back into it */
2212#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
2213#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
2214#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
2215#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
2216
2217const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
2218
2219 MASK_DECLARE_8(0), MASK_DECLARE_8(8),
2220 MASK_DECLARE_8(16), MASK_DECLARE_8(24),
2221#if BITS_PER_LONG > 32
2222 MASK_DECLARE_8(32), MASK_DECLARE_8(40),
2223 MASK_DECLARE_8(48), MASK_DECLARE_8(56),
2224#endif
2225};
2226EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
2227
2228const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
2229EXPORT_SYMBOL(cpu_all_bits);
2230
2231#ifdef CONFIG_INIT_ALL_POSSIBLE
2232struct cpumask __cpu_possible_mask __read_mostly
2233 = {CPU_BITS_ALL};
2234#else
2235struct cpumask __cpu_possible_mask __read_mostly;
2236#endif
2237EXPORT_SYMBOL(__cpu_possible_mask);
2238
2239struct cpumask __cpu_online_mask __read_mostly;
2240EXPORT_SYMBOL(__cpu_online_mask);
2241
2242struct cpumask __cpu_present_mask __read_mostly;
2243EXPORT_SYMBOL(__cpu_present_mask);
2244
2245struct cpumask __cpu_active_mask __read_mostly;
2246EXPORT_SYMBOL(__cpu_active_mask);
2247
2248void init_cpu_present(const struct cpumask *src)
2249{
2250 cpumask_copy(&__cpu_present_mask, src);
2251}
2252
2253void init_cpu_possible(const struct cpumask *src)
2254{
2255 cpumask_copy(&__cpu_possible_mask, src);
2256}
2257
2258void init_cpu_online(const struct cpumask *src)
2259{
2260 cpumask_copy(&__cpu_online_mask, src);
2261}
2262
2263/*
2264 * Activate the first processor.
2265 */
2266void __init boot_cpu_init(void)
2267{
2268 int cpu = smp_processor_id();
2269
2270 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
2271 set_cpu_online(cpu, true);
2272 set_cpu_active(cpu, true);
2273 set_cpu_present(cpu, true);
2274 set_cpu_possible(cpu, true);
2275
2276#ifdef CONFIG_SMP
2277 __boot_cpu_id = cpu;
2278#endif
2279}
2280
2281/*
2282 * Must be called _AFTER_ setting up the per_cpu areas
2283 */
2284void __init boot_cpu_hotplug_init(void)
2285{
2286#ifdef CONFIG_SMP
2287 this_cpu_write(cpuhp_state.booted_once, true);
2288#endif
2289 this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);
2290}
2291