2 * (C) 2001, 2002, 2003, 2004 Rusty Russell
4 * This code is licenced under the GPL.
6 #include <linux/proc_fs.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>
27 #include <trace/events/power.h>
28 #define CREATE_TRACE_POINTS
29 #include <trace/events/cpuhp.h>
34 * cpuhp_cpu_state - Per cpu hotplug state storage
35 * @state: The current cpu state
36 * @target: The target state
37 * @thread: Pointer to the hotplug thread
38 * @should_run: Thread should execute
39 * @rollback: Perform a rollback
40 * @cb_stat: The state for a single callback (install/uninstall)
41 * @cb: Single callback function (install/uninstall)
42 * @result: Result of the operation
43 * @done: Signal completion to the issuer of the task
45 struct cpuhp_cpu_state
{
46 enum cpuhp_state state
;
47 enum cpuhp_state target
;
49 struct task_struct
*thread
;
52 enum cpuhp_state cb_state
;
53 int (*cb
)(unsigned int cpu
);
55 struct completion done
;
59 static DEFINE_PER_CPU(struct cpuhp_cpu_state
, cpuhp_state
);
62 * cpuhp_step - Hotplug state machine step
63 * @name: Name of the step
64 * @startup: Startup function of the step
65 * @teardown: Teardown function of the step
66 * @skip_onerr: Do not invoke the functions on error rollback
67 * Will go away once the notifiers are gone
68 * @cant_stop: Bringup/teardown can't be stopped at this step
72 int (*startup
)(unsigned int cpu
);
73 int (*teardown
)(unsigned int cpu
);
78 static DEFINE_MUTEX(cpuhp_state_mutex
);
79 static struct cpuhp_step cpuhp_bp_states
[];
80 static struct cpuhp_step cpuhp_ap_states
[];
83 * cpuhp_invoke_callback _ Invoke the callbacks for a given state
84 * @cpu: The cpu for which the callback should be invoked
85 * @step: The step in the state machine
86 * @cb: The callback function to invoke
88 * Called from cpu hotplug and from the state register machinery
90 static int cpuhp_invoke_callback(unsigned int cpu
, enum cpuhp_state step
,
91 int (*cb
)(unsigned int))
93 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
97 trace_cpuhp_enter(cpu
, st
->target
, step
, cb
);
99 trace_cpuhp_exit(cpu
, st
->state
, step
, ret
);
105 /* Serializes the updates to cpu_online_mask, cpu_present_mask */
106 static DEFINE_MUTEX(cpu_add_remove_lock
);
107 bool cpuhp_tasks_frozen
;
108 EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen
);
111 * The following two APIs (cpu_maps_update_begin/done) must be used when
112 * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
113 * The APIs cpu_notifier_register_begin/done() must be used to protect CPU
114 * hotplug callback (un)registration performed using __register_cpu_notifier()
115 * or __unregister_cpu_notifier().
117 void cpu_maps_update_begin(void)
119 mutex_lock(&cpu_add_remove_lock
);
121 EXPORT_SYMBOL(cpu_notifier_register_begin
);
123 void cpu_maps_update_done(void)
125 mutex_unlock(&cpu_add_remove_lock
);
127 EXPORT_SYMBOL(cpu_notifier_register_done
);
129 static RAW_NOTIFIER_HEAD(cpu_chain
);
131 /* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
132 * Should always be manipulated under cpu_add_remove_lock
134 static int cpu_hotplug_disabled
;
136 #ifdef CONFIG_HOTPLUG_CPU
139 struct task_struct
*active_writer
;
140 /* wait queue to wake up the active_writer */
141 wait_queue_head_t wq
;
142 /* verifies that no writer will get active while readers are active */
145 * Also blocks the new readers during
146 * an ongoing cpu hotplug operation.
150 #ifdef CONFIG_DEBUG_LOCK_ALLOC
151 struct lockdep_map dep_map
;
154 .active_writer
= NULL
,
155 .wq
= __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug
.wq
),
156 .lock
= __MUTEX_INITIALIZER(cpu_hotplug
.lock
),
157 #ifdef CONFIG_DEBUG_LOCK_ALLOC
158 .dep_map
= {.name
= "cpu_hotplug.lock" },
162 /* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
163 #define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
164 #define cpuhp_lock_acquire_tryread() \
165 lock_map_acquire_tryread(&cpu_hotplug.dep_map)
166 #define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map)
167 #define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map)
170 void get_online_cpus(void)
173 if (cpu_hotplug
.active_writer
== current
)
175 cpuhp_lock_acquire_read();
176 mutex_lock(&cpu_hotplug
.lock
);
177 atomic_inc(&cpu_hotplug
.refcount
);
178 mutex_unlock(&cpu_hotplug
.lock
);
180 EXPORT_SYMBOL_GPL(get_online_cpus
);
182 void put_online_cpus(void)
186 if (cpu_hotplug
.active_writer
== current
)
189 refcount
= atomic_dec_return(&cpu_hotplug
.refcount
);
190 if (WARN_ON(refcount
< 0)) /* try to fix things up */
191 atomic_inc(&cpu_hotplug
.refcount
);
193 if (refcount
<= 0 && waitqueue_active(&cpu_hotplug
.wq
))
194 wake_up(&cpu_hotplug
.wq
);
196 cpuhp_lock_release();
199 EXPORT_SYMBOL_GPL(put_online_cpus
);
202 * This ensures that the hotplug operation can begin only when the
203 * refcount goes to zero.
205 * Note that during a cpu-hotplug operation, the new readers, if any,
206 * will be blocked by the cpu_hotplug.lock
208 * Since cpu_hotplug_begin() is always called after invoking
209 * cpu_maps_update_begin(), we can be sure that only one writer is active.
211 * Note that theoretically, there is a possibility of a livelock:
212 * - Refcount goes to zero, last reader wakes up the sleeping
214 * - Last reader unlocks the cpu_hotplug.lock.
215 * - A new reader arrives at this moment, bumps up the refcount.
216 * - The writer acquires the cpu_hotplug.lock finds the refcount
217 * non zero and goes to sleep again.
219 * However, this is very difficult to achieve in practice since
220 * get_online_cpus() not an api which is called all that often.
223 void cpu_hotplug_begin(void)
227 cpu_hotplug
.active_writer
= current
;
228 cpuhp_lock_acquire();
231 mutex_lock(&cpu_hotplug
.lock
);
232 prepare_to_wait(&cpu_hotplug
.wq
, &wait
, TASK_UNINTERRUPTIBLE
);
233 if (likely(!atomic_read(&cpu_hotplug
.refcount
)))
235 mutex_unlock(&cpu_hotplug
.lock
);
238 finish_wait(&cpu_hotplug
.wq
, &wait
);
241 void cpu_hotplug_done(void)
243 cpu_hotplug
.active_writer
= NULL
;
244 mutex_unlock(&cpu_hotplug
.lock
);
245 cpuhp_lock_release();
249 * Wait for currently running CPU hotplug operations to complete (if any) and
250 * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
251 * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
252 * hotplug path before performing hotplug operations. So acquiring that lock
253 * guarantees mutual exclusion from any currently running hotplug operations.
255 void cpu_hotplug_disable(void)
257 cpu_maps_update_begin();
258 cpu_hotplug_disabled
++;
259 cpu_maps_update_done();
261 EXPORT_SYMBOL_GPL(cpu_hotplug_disable
);
263 void cpu_hotplug_enable(void)
265 cpu_maps_update_begin();
266 WARN_ON(--cpu_hotplug_disabled
< 0);
267 cpu_maps_update_done();
269 EXPORT_SYMBOL_GPL(cpu_hotplug_enable
);
270 #endif /* CONFIG_HOTPLUG_CPU */
272 /* Need to know about CPUs going up/down? */
273 int register_cpu_notifier(struct notifier_block
*nb
)
276 cpu_maps_update_begin();
277 ret
= raw_notifier_chain_register(&cpu_chain
, nb
);
278 cpu_maps_update_done();
282 int __register_cpu_notifier(struct notifier_block
*nb
)
284 return raw_notifier_chain_register(&cpu_chain
, nb
);
287 static int __cpu_notify(unsigned long val
, unsigned int cpu
, int nr_to_call
,
290 unsigned long mod
= cpuhp_tasks_frozen
? CPU_TASKS_FROZEN
: 0;
291 void *hcpu
= (void *)(long)cpu
;
295 ret
= __raw_notifier_call_chain(&cpu_chain
, val
| mod
, hcpu
, nr_to_call
,
298 return notifier_to_errno(ret
);
301 static int cpu_notify(unsigned long val
, unsigned int cpu
)
303 return __cpu_notify(val
, cpu
, -1, NULL
);
306 static void cpu_notify_nofail(unsigned long val
, unsigned int cpu
)
308 BUG_ON(cpu_notify(val
, cpu
));
311 /* Notifier wrappers for transitioning to state machine */
312 static int notify_prepare(unsigned int cpu
)
317 ret
= __cpu_notify(CPU_UP_PREPARE
, cpu
, -1, &nr_calls
);
320 printk(KERN_WARNING
"%s: attempt to bring up CPU %u failed\n",
322 __cpu_notify(CPU_UP_CANCELED
, cpu
, nr_calls
, NULL
);
327 static int notify_online(unsigned int cpu
)
329 cpu_notify(CPU_ONLINE
, cpu
);
333 static int notify_starting(unsigned int cpu
)
335 cpu_notify(CPU_STARTING
, cpu
);
339 static int bringup_wait_for_ap(unsigned int cpu
)
341 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
343 wait_for_completion(&st
->done
);
347 static int bringup_cpu(unsigned int cpu
)
349 struct task_struct
*idle
= idle_thread_get(cpu
);
352 /* Arch-specific enabling code. */
353 ret
= __cpu_up(cpu
, idle
);
355 cpu_notify(CPU_UP_CANCELED
, cpu
);
358 ret
= bringup_wait_for_ap(cpu
);
359 BUG_ON(!cpu_online(cpu
));
364 * Hotplug state machine related functions
366 static void undo_cpu_down(unsigned int cpu
, struct cpuhp_cpu_state
*st
,
367 struct cpuhp_step
*steps
)
369 for (st
->state
++; st
->state
< st
->target
; st
->state
++) {
370 struct cpuhp_step
*step
= steps
+ st
->state
;
372 if (!step
->skip_onerr
)
373 cpuhp_invoke_callback(cpu
, st
->state
, step
->startup
);
377 static int cpuhp_down_callbacks(unsigned int cpu
, struct cpuhp_cpu_state
*st
,
378 struct cpuhp_step
*steps
, enum cpuhp_state target
)
380 enum cpuhp_state prev_state
= st
->state
;
383 for (; st
->state
> target
; st
->state
--) {
384 struct cpuhp_step
*step
= steps
+ st
->state
;
386 ret
= cpuhp_invoke_callback(cpu
, st
->state
, step
->teardown
);
388 st
->target
= prev_state
;
389 undo_cpu_down(cpu
, st
, steps
);
396 static void undo_cpu_up(unsigned int cpu
, struct cpuhp_cpu_state
*st
,
397 struct cpuhp_step
*steps
)
399 for (st
->state
--; st
->state
> st
->target
; st
->state
--) {
400 struct cpuhp_step
*step
= steps
+ st
->state
;
402 if (!step
->skip_onerr
)
403 cpuhp_invoke_callback(cpu
, st
->state
, step
->teardown
);
407 static int cpuhp_up_callbacks(unsigned int cpu
, struct cpuhp_cpu_state
*st
,
408 struct cpuhp_step
*steps
, enum cpuhp_state target
)
410 enum cpuhp_state prev_state
= st
->state
;
413 while (st
->state
< target
) {
414 struct cpuhp_step
*step
;
417 step
= steps
+ st
->state
;
418 ret
= cpuhp_invoke_callback(cpu
, st
->state
, step
->startup
);
420 st
->target
= prev_state
;
421 undo_cpu_up(cpu
, st
, steps
);
429 * The cpu hotplug threads manage the bringup and teardown of the cpus
431 static void cpuhp_create(unsigned int cpu
)
433 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
435 init_completion(&st
->done
);
438 static int cpuhp_should_run(unsigned int cpu
)
440 struct cpuhp_cpu_state
*st
= this_cpu_ptr(&cpuhp_state
);
442 return st
->should_run
;
445 /* Execute the teardown callbacks. Used to be CPU_DOWN_PREPARE */
446 static int cpuhp_ap_offline(unsigned int cpu
, struct cpuhp_cpu_state
*st
)
448 enum cpuhp_state target
= max((int)st
->target
, CPUHP_TEARDOWN_CPU
);
450 return cpuhp_down_callbacks(cpu
, st
, cpuhp_ap_states
, target
);
453 /* Execute the online startup callbacks. Used to be CPU_ONLINE */
454 static int cpuhp_ap_online(unsigned int cpu
, struct cpuhp_cpu_state
*st
)
456 return cpuhp_up_callbacks(cpu
, st
, cpuhp_ap_states
, st
->target
);
460 * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke
461 * callbacks when a state gets [un]installed at runtime.
463 static void cpuhp_thread_fun(unsigned int cpu
)
465 struct cpuhp_cpu_state
*st
= this_cpu_ptr(&cpuhp_state
);
469 * Paired with the mb() in cpuhp_kick_ap_work and
470 * cpuhp_invoke_ap_callback, so the work set is consistent visible.
476 st
->should_run
= false;
478 /* Single callback invocation for [un]install ? */
480 if (st
->cb_state
< CPUHP_AP_ONLINE
) {
482 ret
= cpuhp_invoke_callback(cpu
, st
->cb_state
, st
->cb
);
485 ret
= cpuhp_invoke_callback(cpu
, st
->cb_state
, st
->cb
);
487 } else if (st
->rollback
) {
488 BUG_ON(st
->state
< CPUHP_AP_ONLINE_IDLE
);
490 undo_cpu_down(cpu
, st
, cpuhp_ap_states
);
492 * This is a momentary workaround to keep the notifier users
493 * happy. Will go away once we got rid of the notifiers.
495 cpu_notify_nofail(CPU_DOWN_FAILED
, cpu
);
496 st
->rollback
= false;
498 /* Cannot happen .... */
499 BUG_ON(st
->state
< CPUHP_AP_ONLINE_IDLE
);
501 /* Regular hotplug work */
502 if (st
->state
< st
->target
)
503 ret
= cpuhp_ap_online(cpu
, st
);
504 else if (st
->state
> st
->target
)
505 ret
= cpuhp_ap_offline(cpu
, st
);
511 /* Invoke a single callback on a remote cpu */
512 static int cpuhp_invoke_ap_callback(int cpu
, enum cpuhp_state state
,
513 int (*cb
)(unsigned int))
515 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
517 if (!cpu_online(cpu
))
521 * If we are up and running, use the hotplug thread. For early calls
522 * we invoke the thread function directly.
525 return cpuhp_invoke_callback(cpu
, state
, cb
);
527 st
->cb_state
= state
;
530 * Make sure the above stores are visible before should_run becomes
531 * true. Paired with the mb() above in cpuhp_thread_fun()
534 st
->should_run
= true;
535 wake_up_process(st
->thread
);
536 wait_for_completion(&st
->done
);
540 /* Regular hotplug invocation of the AP hotplug thread */
541 static void __cpuhp_kick_ap_work(struct cpuhp_cpu_state
*st
)
546 * Make sure the above stores are visible before should_run becomes
547 * true. Paired with the mb() above in cpuhp_thread_fun()
550 st
->should_run
= true;
551 wake_up_process(st
->thread
);
554 static int cpuhp_kick_ap_work(unsigned int cpu
)
556 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
557 enum cpuhp_state state
= st
->state
;
559 trace_cpuhp_enter(cpu
, st
->target
, state
, cpuhp_kick_ap_work
);
560 __cpuhp_kick_ap_work(st
);
561 wait_for_completion(&st
->done
);
562 trace_cpuhp_exit(cpu
, st
->state
, state
, st
->result
);
566 static struct smp_hotplug_thread cpuhp_threads
= {
567 .store
= &cpuhp_state
.thread
,
568 .create
= &cpuhp_create
,
569 .thread_should_run
= cpuhp_should_run
,
570 .thread_fn
= cpuhp_thread_fun
,
571 .thread_comm
= "cpuhp/%u",
575 void __init
cpuhp_threads_init(void)
577 BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads
));
578 kthread_unpark(this_cpu_read(cpuhp_state
.thread
));
581 #ifdef CONFIG_HOTPLUG_CPU
582 EXPORT_SYMBOL(register_cpu_notifier
);
583 EXPORT_SYMBOL(__register_cpu_notifier
);
584 void unregister_cpu_notifier(struct notifier_block
*nb
)
586 cpu_maps_update_begin();
587 raw_notifier_chain_unregister(&cpu_chain
, nb
);
588 cpu_maps_update_done();
590 EXPORT_SYMBOL(unregister_cpu_notifier
);
592 void __unregister_cpu_notifier(struct notifier_block
*nb
)
594 raw_notifier_chain_unregister(&cpu_chain
, nb
);
596 EXPORT_SYMBOL(__unregister_cpu_notifier
);
599 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
602 * This function walks all processes, finds a valid mm struct for each one and
603 * then clears a corresponding bit in mm's cpumask. While this all sounds
604 * trivial, there are various non-obvious corner cases, which this function
605 * tries to solve in a safe manner.
607 * Also note that the function uses a somewhat relaxed locking scheme, so it may
608 * be called only for an already offlined CPU.
610 void clear_tasks_mm_cpumask(int cpu
)
612 struct task_struct
*p
;
615 * This function is called after the cpu is taken down and marked
616 * offline, so its not like new tasks will ever get this cpu set in
617 * their mm mask. -- Peter Zijlstra
618 * Thus, we may use rcu_read_lock() here, instead of grabbing
619 * full-fledged tasklist_lock.
621 WARN_ON(cpu_online(cpu
));
623 for_each_process(p
) {
624 struct task_struct
*t
;
627 * Main thread might exit, but other threads may still have
628 * a valid mm. Find one.
630 t
= find_lock_task_mm(p
);
633 cpumask_clear_cpu(cpu
, mm_cpumask(t
->mm
));
639 static inline void check_for_tasks(int dead_cpu
)
641 struct task_struct
*g
, *p
;
643 read_lock(&tasklist_lock
);
644 for_each_process_thread(g
, p
) {
648 * We do the check with unlocked task_rq(p)->lock.
649 * Order the reading to do not warn about a task,
650 * which was running on this cpu in the past, and
651 * it's just been woken on another cpu.
654 if (task_cpu(p
) != dead_cpu
)
657 pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
658 p
->comm
, task_pid_nr(p
), dead_cpu
, p
->state
, p
->flags
);
660 read_unlock(&tasklist_lock
);
663 static int notify_down_prepare(unsigned int cpu
)
665 int err
, nr_calls
= 0;
667 err
= __cpu_notify(CPU_DOWN_PREPARE
, cpu
, -1, &nr_calls
);
670 __cpu_notify(CPU_DOWN_FAILED
, cpu
, nr_calls
, NULL
);
671 pr_warn("%s: attempt to take down CPU %u failed\n",
677 static int notify_dying(unsigned int cpu
)
679 cpu_notify(CPU_DYING
, cpu
);
683 /* Take this CPU down. */
684 static int take_cpu_down(void *_param
)
686 struct cpuhp_cpu_state
*st
= this_cpu_ptr(&cpuhp_state
);
687 enum cpuhp_state target
= max((int)st
->target
, CPUHP_AP_OFFLINE
);
688 int err
, cpu
= smp_processor_id();
690 /* Ensure this CPU doesn't handle any more interrupts. */
691 err
= __cpu_disable();
695 /* Invoke the former CPU_DYING callbacks */
696 for (; st
->state
> target
; st
->state
--) {
697 struct cpuhp_step
*step
= cpuhp_ap_states
+ st
->state
;
699 cpuhp_invoke_callback(cpu
, st
->state
, step
->teardown
);
701 /* Give up timekeeping duties */
702 tick_handover_do_timer();
703 /* Park the stopper thread */
704 stop_machine_park(cpu
);
708 static int takedown_cpu(unsigned int cpu
)
710 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
713 /* Park the smpboot threads */
714 kthread_park(per_cpu_ptr(&cpuhp_state
, cpu
)->thread
);
715 smpboot_park_threads(cpu
);
718 * Prevent irq alloc/free while the dying cpu reorganizes the
719 * interrupt affinities.
724 * So now all preempt/rcu users must observe !cpu_active().
726 err
= stop_machine(take_cpu_down
, NULL
, cpumask_of(cpu
));
728 /* CPU refused to die */
730 /* Unpark the hotplug thread so we can rollback there */
731 kthread_unpark(per_cpu_ptr(&cpuhp_state
, cpu
)->thread
);
734 BUG_ON(cpu_online(cpu
));
737 * The migration_call() CPU_DYING callback will have removed all
738 * runnable tasks from the cpu, there's only the idle task left now
739 * that the migration thread is done doing the stop_machine thing.
741 * Wait for the stop thread to go away.
743 wait_for_completion(&st
->done
);
744 BUG_ON(st
->state
!= CPUHP_AP_IDLE_DEAD
);
746 /* Interrupts are moved away from the dying cpu, reenable alloc/free */
749 hotplug_cpu__broadcast_tick_pull(cpu
);
750 /* This actually kills the CPU. */
753 tick_cleanup_dead_cpu(cpu
);
757 static int notify_dead(unsigned int cpu
)
759 cpu_notify_nofail(CPU_DEAD
, cpu
);
760 check_for_tasks(cpu
);
764 static void cpuhp_complete_idle_dead(void *arg
)
766 struct cpuhp_cpu_state
*st
= arg
;
771 void cpuhp_report_idle_dead(void)
773 struct cpuhp_cpu_state
*st
= this_cpu_ptr(&cpuhp_state
);
775 BUG_ON(st
->state
!= CPUHP_AP_OFFLINE
);
776 rcu_report_dead(smp_processor_id());
777 st
->state
= CPUHP_AP_IDLE_DEAD
;
779 * We cannot call complete after rcu_report_dead() so we delegate it
782 smp_call_function_single(cpumask_first(cpu_online_mask
),
783 cpuhp_complete_idle_dead
, st
, 0);
787 #define notify_down_prepare NULL
788 #define takedown_cpu NULL
789 #define notify_dead NULL
790 #define notify_dying NULL
793 #ifdef CONFIG_HOTPLUG_CPU
795 /* Requires cpu_add_remove_lock to be held */
796 static int __ref
_cpu_down(unsigned int cpu
, int tasks_frozen
,
797 enum cpuhp_state target
)
799 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
800 int prev_state
, ret
= 0;
801 bool hasdied
= false;
803 if (num_online_cpus() == 1)
806 if (!cpu_present(cpu
))
811 cpuhp_tasks_frozen
= tasks_frozen
;
813 prev_state
= st
->state
;
816 * If the current CPU state is in the range of the AP hotplug thread,
817 * then we need to kick the thread.
819 if (st
->state
> CPUHP_TEARDOWN_CPU
) {
820 ret
= cpuhp_kick_ap_work(cpu
);
822 * The AP side has done the error rollback already. Just
823 * return the error code..
829 * We might have stopped still in the range of the AP hotplug
830 * thread. Nothing to do anymore.
832 if (st
->state
> CPUHP_TEARDOWN_CPU
)
836 * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need
837 * to do the further cleanups.
839 ret
= cpuhp_down_callbacks(cpu
, st
, cpuhp_bp_states
, target
);
840 if (ret
&& st
->state
> CPUHP_TEARDOWN_CPU
&& st
->state
< prev_state
) {
841 st
->target
= prev_state
;
843 cpuhp_kick_ap_work(cpu
);
846 hasdied
= prev_state
!= st
->state
&& st
->state
== CPUHP_OFFLINE
;
849 /* This post dead nonsense must die */
851 cpu_notify_nofail(CPU_POST_DEAD
, cpu
);
855 static int do_cpu_down(unsigned int cpu
, enum cpuhp_state target
)
859 cpu_maps_update_begin();
861 if (cpu_hotplug_disabled
) {
866 err
= _cpu_down(cpu
, 0, target
);
869 cpu_maps_update_done();
872 int cpu_down(unsigned int cpu
)
874 return do_cpu_down(cpu
, CPUHP_OFFLINE
);
876 EXPORT_SYMBOL(cpu_down
);
877 #endif /*CONFIG_HOTPLUG_CPU*/
880 * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
881 * @cpu: cpu that just started
883 * This function calls the cpu_chain notifiers with CPU_STARTING.
884 * It must be called by the arch code on the new cpu, before the new cpu
885 * enables interrupts and before the "boot" cpu returns from __cpu_up().
887 void notify_cpu_starting(unsigned int cpu
)
889 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
890 enum cpuhp_state target
= min((int)st
->target
, CPUHP_AP_ONLINE
);
892 while (st
->state
< target
) {
893 struct cpuhp_step
*step
;
896 step
= cpuhp_ap_states
+ st
->state
;
897 cpuhp_invoke_callback(cpu
, st
->state
, step
->startup
);
902 * Called from the idle task. We need to set active here, so we can kick off
903 * the stopper thread and unpark the smpboot threads. If the target state is
904 * beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the
907 void cpuhp_online_idle(enum cpuhp_state state
)
909 struct cpuhp_cpu_state
*st
= this_cpu_ptr(&cpuhp_state
);
910 unsigned int cpu
= smp_processor_id();
912 /* Happens for the boot cpu */
913 if (state
!= CPUHP_AP_ONLINE_IDLE
)
916 st
->state
= CPUHP_AP_ONLINE_IDLE
;
918 /* Unpark the stopper thread and the hotplug thread of this cpu */
919 stop_machine_unpark(cpu
);
920 kthread_unpark(st
->thread
);
922 /* Should we go further up ? */
923 if (st
->target
> CPUHP_AP_ONLINE_IDLE
)
924 __cpuhp_kick_ap_work(st
);
929 /* Requires cpu_add_remove_lock to be held */
930 static int _cpu_up(unsigned int cpu
, int tasks_frozen
, enum cpuhp_state target
)
932 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
933 struct task_struct
*idle
;
938 if (!cpu_present(cpu
)) {
944 * The caller of do_cpu_up might have raced with another
945 * caller. Ignore it for now.
947 if (st
->state
>= target
)
950 if (st
->state
== CPUHP_OFFLINE
) {
951 /* Let it fail before we try to bring the cpu up */
952 idle
= idle_thread_get(cpu
);
959 cpuhp_tasks_frozen
= tasks_frozen
;
963 * If the current CPU state is in the range of the AP hotplug thread,
964 * then we need to kick the thread once more.
966 if (st
->state
> CPUHP_BRINGUP_CPU
) {
967 ret
= cpuhp_kick_ap_work(cpu
);
969 * The AP side has done the error rollback already. Just
970 * return the error code..
977 * Try to reach the target state. We max out on the BP at
978 * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
979 * responsible for bringing it up to the target state.
981 target
= min((int)target
, CPUHP_BRINGUP_CPU
);
982 ret
= cpuhp_up_callbacks(cpu
, st
, cpuhp_bp_states
, target
);
988 static int do_cpu_up(unsigned int cpu
, enum cpuhp_state target
)
992 if (!cpu_possible(cpu
)) {
993 pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
995 #if defined(CONFIG_IA64)
996 pr_err("please check additional_cpus= boot parameter\n");
1001 err
= try_online_node(cpu_to_node(cpu
));
1005 cpu_maps_update_begin();
1007 if (cpu_hotplug_disabled
) {
1012 err
= _cpu_up(cpu
, 0, target
);
1014 cpu_maps_update_done();
1018 int cpu_up(unsigned int cpu
)
1020 return do_cpu_up(cpu
, CPUHP_ONLINE
);
1022 EXPORT_SYMBOL_GPL(cpu_up
);
1024 #ifdef CONFIG_PM_SLEEP_SMP
1025 static cpumask_var_t frozen_cpus
;
1027 int freeze_secondary_cpus(int primary
)
1031 cpu_maps_update_begin();
1032 if (!cpu_online(primary
))
1033 primary
= cpumask_first(cpu_online_mask
);
1035 * We take down all of the non-boot CPUs in one shot to avoid races
1036 * with the userspace trying to use the CPU hotplug at the same time
1038 cpumask_clear(frozen_cpus
);
1040 pr_info("Disabling non-boot CPUs ...\n");
1041 for_each_online_cpu(cpu
) {
1044 trace_suspend_resume(TPS("CPU_OFF"), cpu
, true);
1045 error
= _cpu_down(cpu
, 1, CPUHP_OFFLINE
);
1046 trace_suspend_resume(TPS("CPU_OFF"), cpu
, false);
1048 cpumask_set_cpu(cpu
, frozen_cpus
);
1050 pr_err("Error taking CPU%d down: %d\n", cpu
, error
);
1056 BUG_ON(num_online_cpus() > 1);
1058 pr_err("Non-boot CPUs are not disabled\n");
1061 * Make sure the CPUs won't be enabled by someone else. We need to do
1062 * this even in case of failure as all disable_nonboot_cpus() users are
1063 * supposed to do enable_nonboot_cpus() on the failure path.
1065 cpu_hotplug_disabled
++;
1067 cpu_maps_update_done();
1071 void __weak
arch_enable_nonboot_cpus_begin(void)
1075 void __weak
arch_enable_nonboot_cpus_end(void)
1079 void enable_nonboot_cpus(void)
1083 /* Allow everyone to use the CPU hotplug again */
1084 cpu_maps_update_begin();
1085 WARN_ON(--cpu_hotplug_disabled
< 0);
1086 if (cpumask_empty(frozen_cpus
))
1089 pr_info("Enabling non-boot CPUs ...\n");
1091 arch_enable_nonboot_cpus_begin();
1093 for_each_cpu(cpu
, frozen_cpus
) {
1094 trace_suspend_resume(TPS("CPU_ON"), cpu
, true);
1095 error
= _cpu_up(cpu
, 1, CPUHP_ONLINE
);
1096 trace_suspend_resume(TPS("CPU_ON"), cpu
, false);
1098 pr_info("CPU%d is up\n", cpu
);
1101 pr_warn("Error taking CPU%d up: %d\n", cpu
, error
);
1104 arch_enable_nonboot_cpus_end();
1106 cpumask_clear(frozen_cpus
);
1108 cpu_maps_update_done();
1111 static int __init
alloc_frozen_cpus(void)
1113 if (!alloc_cpumask_var(&frozen_cpus
, GFP_KERNEL
|__GFP_ZERO
))
1117 core_initcall(alloc_frozen_cpus
);
1120 * When callbacks for CPU hotplug notifications are being executed, we must
1121 * ensure that the state of the system with respect to the tasks being frozen
1122 * or not, as reported by the notification, remains unchanged *throughout the
1123 * duration* of the execution of the callbacks.
1124 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
1126 * This synchronization is implemented by mutually excluding regular CPU
1127 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
1128 * Hibernate notifications.
1131 cpu_hotplug_pm_callback(struct notifier_block
*nb
,
1132 unsigned long action
, void *ptr
)
1136 case PM_SUSPEND_PREPARE
:
1137 case PM_HIBERNATION_PREPARE
:
1138 cpu_hotplug_disable();
1141 case PM_POST_SUSPEND
:
1142 case PM_POST_HIBERNATION
:
1143 cpu_hotplug_enable();
1154 static int __init
cpu_hotplug_pm_sync_init(void)
1157 * cpu_hotplug_pm_callback has higher priority than x86
1158 * bsp_pm_callback which depends on cpu_hotplug_pm_callback
1159 * to disable cpu hotplug to avoid cpu hotplug race.
1161 pm_notifier(cpu_hotplug_pm_callback
, 0);
1164 core_initcall(cpu_hotplug_pm_sync_init
);
1166 #endif /* CONFIG_PM_SLEEP_SMP */
1168 #endif /* CONFIG_SMP */
1170 /* Boot processor state steps */
1171 static struct cpuhp_step cpuhp_bp_states
[] = {
1178 [CPUHP_CREATE_THREADS
]= {
1179 .name
= "threads:create",
1180 .startup
= smpboot_create_threads
,
1184 [CPUHP_PERF_PREPARE
] = {
1185 .name
= "perf prepare",
1186 .startup
= perf_event_init_cpu
,
1187 .teardown
= perf_event_exit_cpu
,
1189 [CPUHP_WORKQUEUE_PREP
] = {
1190 .name
= "workqueue prepare",
1191 .startup
= workqueue_prepare_cpu
,
1194 [CPUHP_HRTIMERS_PREPARE
] = {
1195 .name
= "hrtimers prepare",
1196 .startup
= hrtimers_prepare_cpu
,
1197 .teardown
= hrtimers_dead_cpu
,
1199 [CPUHP_SMPCFD_PREPARE
] = {
1200 .name
= "SMPCFD prepare",
1201 .startup
= smpcfd_prepare_cpu
,
1202 .teardown
= smpcfd_dead_cpu
,
1204 [CPUHP_RCUTREE_PREP
] = {
1205 .name
= "RCU-tree prepare",
1206 .startup
= rcutree_prepare_cpu
,
1207 .teardown
= rcutree_dead_cpu
,
1210 * Preparatory and dead notifiers. Will be replaced once the notifiers
1211 * are converted to states.
1213 [CPUHP_NOTIFY_PREPARE
] = {
1214 .name
= "notify:prepare",
1215 .startup
= notify_prepare
,
1216 .teardown
= notify_dead
,
1221 * On the tear-down path, timers_dead_cpu() must be invoked
1222 * before blk_mq_queue_reinit_notify() from notify_dead(),
1223 * otherwise a RCU stall occurs.
1225 [CPUHP_TIMERS_DEAD
] = {
1226 .name
= "timers dead",
1228 .teardown
= timers_dead_cpu
,
1230 /* Kicks the plugged cpu into life */
1231 [CPUHP_BRINGUP_CPU
] = {
1232 .name
= "cpu:bringup",
1233 .startup
= bringup_cpu
,
1237 [CPUHP_AP_SMPCFD_DYING
] = {
1239 .teardown
= smpcfd_dying_cpu
,
1242 * Handled on controll processor until the plugged processor manages
1245 [CPUHP_TEARDOWN_CPU
] = {
1246 .name
= "cpu:teardown",
1248 .teardown
= takedown_cpu
,
1252 [CPUHP_BRINGUP_CPU
] = { },
1256 /* Application processor state steps */
1257 static struct cpuhp_step cpuhp_ap_states
[] = {
1259 /* Final state before CPU kills itself */
1260 [CPUHP_AP_IDLE_DEAD
] = {
1261 .name
= "idle:dead",
1264 * Last state before CPU enters the idle loop to die. Transient state
1265 * for synchronization.
1267 [CPUHP_AP_OFFLINE
] = {
1268 .name
= "ap:offline",
1271 /* First state is scheduler control. Interrupts are disabled */
1272 [CPUHP_AP_SCHED_STARTING
] = {
1273 .name
= "sched:starting",
1274 .startup
= sched_cpu_starting
,
1275 .teardown
= sched_cpu_dying
,
1277 [CPUHP_AP_RCUTREE_DYING
] = {
1279 .teardown
= rcutree_dying_cpu
,
1282 * Low level startup/teardown notifiers. Run with interrupts
1283 * disabled. Will be removed once the notifiers are converted to
1286 [CPUHP_AP_NOTIFY_STARTING
] = {
1287 .name
= "notify:starting",
1288 .startup
= notify_starting
,
1289 .teardown
= notify_dying
,
1293 /* Entry state on starting. Interrupts enabled from here on. Transient
1294 * state for synchronsization */
1295 [CPUHP_AP_ONLINE
] = {
1296 .name
= "ap:online",
1298 /* Handle smpboot threads park/unpark */
1299 [CPUHP_AP_SMPBOOT_THREADS
] = {
1300 .name
= "smpboot:threads",
1301 .startup
= smpboot_unpark_threads
,
1304 [CPUHP_AP_PERF_ONLINE
] = {
1305 .name
= "perf online",
1306 .startup
= perf_event_init_cpu
,
1307 .teardown
= perf_event_exit_cpu
,
1309 [CPUHP_AP_WORKQUEUE_ONLINE
] = {
1310 .name
= "workqueue online",
1311 .startup
= workqueue_online_cpu
,
1312 .teardown
= workqueue_offline_cpu
,
1314 [CPUHP_AP_RCUTREE_ONLINE
] = {
1315 .name
= "RCU-tree online",
1316 .startup
= rcutree_online_cpu
,
1317 .teardown
= rcutree_offline_cpu
,
1321 * Online/down_prepare notifiers. Will be removed once the notifiers
1322 * are converted to states.
1324 [CPUHP_AP_NOTIFY_ONLINE
] = {
1325 .name
= "notify:online",
1326 .startup
= notify_online
,
1327 .teardown
= notify_down_prepare
,
1332 * The dynamically registered state space is here
1336 /* Last state is scheduler control setting the cpu active */
1337 [CPUHP_AP_ACTIVE
] = {
1338 .name
= "sched:active",
1339 .startup
= sched_cpu_activate
,
1340 .teardown
= sched_cpu_deactivate
,
1344 /* CPU is fully up and running. */
1352 /* Sanity check for callbacks */
1353 static int cpuhp_cb_check(enum cpuhp_state state
)
1355 if (state
<= CPUHP_OFFLINE
|| state
>= CPUHP_ONLINE
)
1360 static bool cpuhp_is_ap_state(enum cpuhp_state state
)
1363 * The extra check for CPUHP_TEARDOWN_CPU is only for documentation
1364 * purposes as that state is handled explicitely in cpu_down.
1366 return state
> CPUHP_BRINGUP_CPU
&& state
!= CPUHP_TEARDOWN_CPU
;
1369 static struct cpuhp_step
*cpuhp_get_step(enum cpuhp_state state
)
1371 struct cpuhp_step
*sp
;
1373 sp
= cpuhp_is_ap_state(state
) ? cpuhp_ap_states
: cpuhp_bp_states
;
1377 static void cpuhp_store_callbacks(enum cpuhp_state state
,
1379 int (*startup
)(unsigned int cpu
),
1380 int (*teardown
)(unsigned int cpu
))
1382 /* (Un)Install the callbacks for further cpu hotplug operations */
1383 struct cpuhp_step
*sp
;
1385 mutex_lock(&cpuhp_state_mutex
);
1386 sp
= cpuhp_get_step(state
);
1387 sp
->startup
= startup
;
1388 sp
->teardown
= teardown
;
1390 mutex_unlock(&cpuhp_state_mutex
);
1393 static void *cpuhp_get_teardown_cb(enum cpuhp_state state
)
1395 return cpuhp_get_step(state
)->teardown
;
1399 * Call the startup/teardown function for a step either on the AP or
1400 * on the current CPU.
1402 static int cpuhp_issue_call(int cpu
, enum cpuhp_state state
,
1403 int (*cb
)(unsigned int), bool bringup
)
1410 * The non AP bound callbacks can fail on bringup. On teardown
1411 * e.g. module removal we crash for now.
1414 if (cpuhp_is_ap_state(state
))
1415 ret
= cpuhp_invoke_ap_callback(cpu
, state
, cb
);
1417 ret
= cpuhp_invoke_callback(cpu
, state
, cb
);
1419 ret
= cpuhp_invoke_callback(cpu
, state
, cb
);
1421 BUG_ON(ret
&& !bringup
);
1426 * Called from __cpuhp_setup_state on a recoverable failure.
1428 * Note: The teardown callbacks for rollback are not allowed to fail!
1430 static void cpuhp_rollback_install(int failedcpu
, enum cpuhp_state state
,
1431 int (*teardown
)(unsigned int cpu
))
1438 /* Roll back the already executed steps on the other cpus */
1439 for_each_present_cpu(cpu
) {
1440 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
1441 int cpustate
= st
->state
;
1443 if (cpu
>= failedcpu
)
1446 /* Did we invoke the startup call on that cpu ? */
1447 if (cpustate
>= state
)
1448 cpuhp_issue_call(cpu
, state
, teardown
, false);
1453 * Returns a free for dynamic slot assignment of the Online state. The states
1454 * are protected by the cpuhp_slot_states mutex and an empty slot is identified
1455 * by having no name assigned.
1457 static int cpuhp_reserve_state(enum cpuhp_state state
)
1461 mutex_lock(&cpuhp_state_mutex
);
1462 for (i
= CPUHP_AP_ONLINE_DYN
; i
<= CPUHP_AP_ONLINE_DYN_END
; i
++) {
1463 if (cpuhp_ap_states
[i
].name
)
1466 cpuhp_ap_states
[i
].name
= "Reserved";
1467 mutex_unlock(&cpuhp_state_mutex
);
1470 mutex_unlock(&cpuhp_state_mutex
);
1471 WARN(1, "No more dynamic states available for CPU hotplug\n");
1476 * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state
1477 * @state: The state to setup
1478 * @invoke: If true, the startup function is invoked for cpus where
1479 * cpu state >= @state
1480 * @startup: startup callback function
1481 * @teardown: teardown callback function
1483 * Returns 0 if successful, otherwise a proper error code
1485 int __cpuhp_setup_state(enum cpuhp_state state
,
1486 const char *name
, bool invoke
,
1487 int (*startup
)(unsigned int cpu
),
1488 int (*teardown
)(unsigned int cpu
))
1493 if (cpuhp_cb_check(state
) || !name
)
1498 /* currently assignments for the ONLINE state are possible */
1499 if (state
== CPUHP_AP_ONLINE_DYN
) {
1501 ret
= cpuhp_reserve_state(state
);
1507 cpuhp_store_callbacks(state
, name
, startup
, teardown
);
1509 if (!invoke
|| !startup
)
1513 * Try to call the startup callback for each present cpu
1514 * depending on the hotplug state of the cpu.
1516 for_each_present_cpu(cpu
) {
1517 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
1518 int cpustate
= st
->state
;
1520 if (cpustate
< state
)
1523 ret
= cpuhp_issue_call(cpu
, state
, startup
, true);
1525 cpuhp_rollback_install(cpu
, state
, teardown
);
1526 cpuhp_store_callbacks(state
, NULL
, NULL
, NULL
);
1532 if (!ret
&& dyn_state
)
1536 EXPORT_SYMBOL(__cpuhp_setup_state
);
1539 * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state
1540 * @state: The state to remove
1541 * @invoke: If true, the teardown function is invoked for cpus where
1542 * cpu state >= @state
1544 * The teardown callback is currently not allowed to fail. Think
1545 * about module removal!
1547 void __cpuhp_remove_state(enum cpuhp_state state
, bool invoke
)
1549 int (*teardown
)(unsigned int cpu
) = cpuhp_get_teardown_cb(state
);
1552 BUG_ON(cpuhp_cb_check(state
));
1556 if (!invoke
|| !teardown
)
1560 * Call the teardown callback for each present cpu depending
1561 * on the hotplug state of the cpu. This function is not
1562 * allowed to fail currently!
1564 for_each_present_cpu(cpu
) {
1565 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, cpu
);
1566 int cpustate
= st
->state
;
1568 if (cpustate
>= state
)
1569 cpuhp_issue_call(cpu
, state
, teardown
, false);
1572 cpuhp_store_callbacks(state
, NULL
, NULL
, NULL
);
1575 EXPORT_SYMBOL(__cpuhp_remove_state
);
1577 #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
1578 static ssize_t
show_cpuhp_state(struct device
*dev
,
1579 struct device_attribute
*attr
, char *buf
)
1581 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, dev
->id
);
1583 return sprintf(buf
, "%d\n", st
->state
);
1585 static DEVICE_ATTR(state
, 0444, show_cpuhp_state
, NULL
);
1587 static ssize_t
write_cpuhp_target(struct device
*dev
,
1588 struct device_attribute
*attr
,
1589 const char *buf
, size_t count
)
1591 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, dev
->id
);
1592 struct cpuhp_step
*sp
;
1595 ret
= kstrtoint(buf
, 10, &target
);
1599 #ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
1600 if (target
< CPUHP_OFFLINE
|| target
> CPUHP_ONLINE
)
1603 if (target
!= CPUHP_OFFLINE
&& target
!= CPUHP_ONLINE
)
1607 ret
= lock_device_hotplug_sysfs();
1611 mutex_lock(&cpuhp_state_mutex
);
1612 sp
= cpuhp_get_step(target
);
1613 ret
= !sp
->name
|| sp
->cant_stop
? -EINVAL
: 0;
1614 mutex_unlock(&cpuhp_state_mutex
);
1618 if (st
->state
< target
)
1619 ret
= do_cpu_up(dev
->id
, target
);
1621 ret
= do_cpu_down(dev
->id
, target
);
1623 unlock_device_hotplug();
1624 return ret
? ret
: count
;
1627 static ssize_t
show_cpuhp_target(struct device
*dev
,
1628 struct device_attribute
*attr
, char *buf
)
1630 struct cpuhp_cpu_state
*st
= per_cpu_ptr(&cpuhp_state
, dev
->id
);
1632 return sprintf(buf
, "%d\n", st
->target
);
1634 static DEVICE_ATTR(target
, 0644, show_cpuhp_target
, write_cpuhp_target
);
1636 static struct attribute
*cpuhp_cpu_attrs
[] = {
1637 &dev_attr_state
.attr
,
1638 &dev_attr_target
.attr
,
1642 static struct attribute_group cpuhp_cpu_attr_group
= {
1643 .attrs
= cpuhp_cpu_attrs
,
1648 static ssize_t
show_cpuhp_states(struct device
*dev
,
1649 struct device_attribute
*attr
, char *buf
)
1651 ssize_t cur
, res
= 0;
1654 mutex_lock(&cpuhp_state_mutex
);
1655 for (i
= CPUHP_OFFLINE
; i
<= CPUHP_ONLINE
; i
++) {
1656 struct cpuhp_step
*sp
= cpuhp_get_step(i
);
1659 cur
= sprintf(buf
, "%3d: %s\n", i
, sp
->name
);
1664 mutex_unlock(&cpuhp_state_mutex
);
1667 static DEVICE_ATTR(states
, 0444, show_cpuhp_states
, NULL
);
1669 static struct attribute
*cpuhp_cpu_root_attrs
[] = {
1670 &dev_attr_states
.attr
,
1674 static struct attribute_group cpuhp_cpu_root_attr_group
= {
1675 .attrs
= cpuhp_cpu_root_attrs
,
1680 static int __init
cpuhp_sysfs_init(void)
1684 ret
= sysfs_create_group(&cpu_subsys
.dev_root
->kobj
,
1685 &cpuhp_cpu_root_attr_group
);
1689 for_each_possible_cpu(cpu
) {
1690 struct device
*dev
= get_cpu_device(cpu
);
1694 ret
= sysfs_create_group(&dev
->kobj
, &cpuhp_cpu_attr_group
);
1700 device_initcall(cpuhp_sysfs_init
);
1704 * cpu_bit_bitmap[] is a special, "compressed" data structure that
1705 * represents all NR_CPUS bits binary values of 1<<nr.
1707 * It is used by cpumask_of() to get a constant address to a CPU
1708 * mask value that has a single bit set only.
1711 /* cpu_bit_bitmap[0] is empty - so we can back into it */
1712 #define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
1713 #define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
1714 #define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
1715 #define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
1717 const unsigned long cpu_bit_bitmap
[BITS_PER_LONG
+1][BITS_TO_LONGS(NR_CPUS
)] = {
1719 MASK_DECLARE_8(0), MASK_DECLARE_8(8),
1720 MASK_DECLARE_8(16), MASK_DECLARE_8(24),
1721 #if BITS_PER_LONG > 32
1722 MASK_DECLARE_8(32), MASK_DECLARE_8(40),
1723 MASK_DECLARE_8(48), MASK_DECLARE_8(56),
1726 EXPORT_SYMBOL_GPL(cpu_bit_bitmap
);
1728 const DECLARE_BITMAP(cpu_all_bits
, NR_CPUS
) = CPU_BITS_ALL
;
1729 EXPORT_SYMBOL(cpu_all_bits
);
1731 #ifdef CONFIG_INIT_ALL_POSSIBLE
1732 struct cpumask __cpu_possible_mask __read_mostly
1735 struct cpumask __cpu_possible_mask __read_mostly
;
1737 EXPORT_SYMBOL(__cpu_possible_mask
);
1739 struct cpumask __cpu_online_mask __read_mostly
;
1740 EXPORT_SYMBOL(__cpu_online_mask
);
1742 struct cpumask __cpu_present_mask __read_mostly
;
1743 EXPORT_SYMBOL(__cpu_present_mask
);
1745 struct cpumask __cpu_active_mask __read_mostly
;
1746 EXPORT_SYMBOL(__cpu_active_mask
);
1748 void init_cpu_present(const struct cpumask
*src
)
1750 cpumask_copy(&__cpu_present_mask
, src
);
1753 void init_cpu_possible(const struct cpumask
*src
)
1755 cpumask_copy(&__cpu_possible_mask
, src
);
1758 void init_cpu_online(const struct cpumask
*src
)
1760 cpumask_copy(&__cpu_online_mask
, src
);
1764 * Activate the first processor.
1766 void __init
boot_cpu_init(void)
1768 int cpu
= smp_processor_id();
1770 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
1771 set_cpu_online(cpu
, true);
1772 set_cpu_active(cpu
, true);
1773 set_cpu_present(cpu
, true);
1774 set_cpu_possible(cpu
, true);
1778 * Must be called _AFTER_ setting up the per_cpu areas
1780 void __init
boot_cpu_state_init(void)
1782 per_cpu_ptr(&cpuhp_state
, smp_processor_id())->state
= CPUHP_ONLINE
;