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Commit | Line | Data |
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1da177e4 LT |
1 | /* CPU control. |
2 | * (C) 2001, 2002, 2003, 2004 Rusty Russell | |
3 | * | |
4 | * This code is licenced under the GPL. | |
5 | */ | |
6 | #include <linux/proc_fs.h> | |
7 | #include <linux/smp.h> | |
8 | #include <linux/init.h> | |
9 | #include <linux/notifier.h> | |
10 | #include <linux/sched.h> | |
11 | #include <linux/unistd.h> | |
12 | #include <linux/cpu.h> | |
cb79295e AV |
13 | #include <linux/oom.h> |
14 | #include <linux/rcupdate.h> | |
9984de1a | 15 | #include <linux/export.h> |
e4cc2f87 | 16 | #include <linux/bug.h> |
1da177e4 LT |
17 | #include <linux/kthread.h> |
18 | #include <linux/stop_machine.h> | |
81615b62 | 19 | #include <linux/mutex.h> |
5a0e3ad6 | 20 | #include <linux/gfp.h> |
79cfbdfa | 21 | #include <linux/suspend.h> |
a19423b9 | 22 | #include <linux/lockdep.h> |
345527b1 | 23 | #include <linux/tick.h> |
a8994181 | 24 | #include <linux/irq.h> |
bb3632c6 | 25 | #include <trace/events/power.h> |
1da177e4 | 26 | |
38498a67 TG |
27 | #include "smpboot.h" |
28 | ||
98a79d6a | 29 | #ifdef CONFIG_SMP |
b3199c02 | 30 | /* Serializes the updates to cpu_online_mask, cpu_present_mask */ |
aa953877 | 31 | static DEFINE_MUTEX(cpu_add_remove_lock); |
090e77c3 TG |
32 | bool cpuhp_tasks_frozen; |
33 | EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen); | |
1da177e4 | 34 | |
79a6cdeb | 35 | /* |
93ae4f97 SB |
36 | * The following two APIs (cpu_maps_update_begin/done) must be used when |
37 | * attempting to serialize the updates to cpu_online_mask & cpu_present_mask. | |
38 | * The APIs cpu_notifier_register_begin/done() must be used to protect CPU | |
39 | * hotplug callback (un)registration performed using __register_cpu_notifier() | |
40 | * or __unregister_cpu_notifier(). | |
79a6cdeb LJ |
41 | */ |
42 | void cpu_maps_update_begin(void) | |
43 | { | |
44 | mutex_lock(&cpu_add_remove_lock); | |
45 | } | |
93ae4f97 | 46 | EXPORT_SYMBOL(cpu_notifier_register_begin); |
79a6cdeb LJ |
47 | |
48 | void cpu_maps_update_done(void) | |
49 | { | |
50 | mutex_unlock(&cpu_add_remove_lock); | |
51 | } | |
93ae4f97 | 52 | EXPORT_SYMBOL(cpu_notifier_register_done); |
79a6cdeb | 53 | |
5c113fbe | 54 | static RAW_NOTIFIER_HEAD(cpu_chain); |
1da177e4 | 55 | |
e3920fb4 RW |
56 | /* If set, cpu_up and cpu_down will return -EBUSY and do nothing. |
57 | * Should always be manipulated under cpu_add_remove_lock | |
58 | */ | |
59 | static int cpu_hotplug_disabled; | |
60 | ||
79a6cdeb LJ |
61 | #ifdef CONFIG_HOTPLUG_CPU |
62 | ||
d221938c GS |
63 | static struct { |
64 | struct task_struct *active_writer; | |
87af9e7f DH |
65 | /* wait queue to wake up the active_writer */ |
66 | wait_queue_head_t wq; | |
67 | /* verifies that no writer will get active while readers are active */ | |
68 | struct mutex lock; | |
d221938c GS |
69 | /* |
70 | * Also blocks the new readers during | |
71 | * an ongoing cpu hotplug operation. | |
72 | */ | |
87af9e7f | 73 | atomic_t refcount; |
a19423b9 GS |
74 | |
75 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
76 | struct lockdep_map dep_map; | |
77 | #endif | |
31950eb6 LT |
78 | } cpu_hotplug = { |
79 | .active_writer = NULL, | |
87af9e7f | 80 | .wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq), |
31950eb6 | 81 | .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock), |
a19423b9 GS |
82 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
83 | .dep_map = {.name = "cpu_hotplug.lock" }, | |
84 | #endif | |
31950eb6 | 85 | }; |
d221938c | 86 | |
a19423b9 GS |
87 | /* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */ |
88 | #define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map) | |
dd56af42 PM |
89 | #define cpuhp_lock_acquire_tryread() \ |
90 | lock_map_acquire_tryread(&cpu_hotplug.dep_map) | |
a19423b9 GS |
91 | #define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map) |
92 | #define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map) | |
93 | ||
62db99f4 | 94 | |
86ef5c9a | 95 | void get_online_cpus(void) |
a9d9baa1 | 96 | { |
d221938c GS |
97 | might_sleep(); |
98 | if (cpu_hotplug.active_writer == current) | |
aa953877 | 99 | return; |
a19423b9 | 100 | cpuhp_lock_acquire_read(); |
d221938c | 101 | mutex_lock(&cpu_hotplug.lock); |
87af9e7f | 102 | atomic_inc(&cpu_hotplug.refcount); |
d221938c | 103 | mutex_unlock(&cpu_hotplug.lock); |
a9d9baa1 | 104 | } |
86ef5c9a | 105 | EXPORT_SYMBOL_GPL(get_online_cpus); |
90d45d17 | 106 | |
86ef5c9a | 107 | void put_online_cpus(void) |
a9d9baa1 | 108 | { |
87af9e7f DH |
109 | int refcount; |
110 | ||
d221938c | 111 | if (cpu_hotplug.active_writer == current) |
aa953877 | 112 | return; |
075663d1 | 113 | |
87af9e7f DH |
114 | refcount = atomic_dec_return(&cpu_hotplug.refcount); |
115 | if (WARN_ON(refcount < 0)) /* try to fix things up */ | |
116 | atomic_inc(&cpu_hotplug.refcount); | |
117 | ||
118 | if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq)) | |
119 | wake_up(&cpu_hotplug.wq); | |
075663d1 | 120 | |
a19423b9 | 121 | cpuhp_lock_release(); |
d221938c | 122 | |
a9d9baa1 | 123 | } |
86ef5c9a | 124 | EXPORT_SYMBOL_GPL(put_online_cpus); |
a9d9baa1 | 125 | |
d221938c GS |
126 | /* |
127 | * This ensures that the hotplug operation can begin only when the | |
128 | * refcount goes to zero. | |
129 | * | |
130 | * Note that during a cpu-hotplug operation, the new readers, if any, | |
131 | * will be blocked by the cpu_hotplug.lock | |
132 | * | |
d2ba7e2a ON |
133 | * Since cpu_hotplug_begin() is always called after invoking |
134 | * cpu_maps_update_begin(), we can be sure that only one writer is active. | |
d221938c GS |
135 | * |
136 | * Note that theoretically, there is a possibility of a livelock: | |
137 | * - Refcount goes to zero, last reader wakes up the sleeping | |
138 | * writer. | |
139 | * - Last reader unlocks the cpu_hotplug.lock. | |
140 | * - A new reader arrives at this moment, bumps up the refcount. | |
141 | * - The writer acquires the cpu_hotplug.lock finds the refcount | |
142 | * non zero and goes to sleep again. | |
143 | * | |
144 | * However, this is very difficult to achieve in practice since | |
86ef5c9a | 145 | * get_online_cpus() not an api which is called all that often. |
d221938c GS |
146 | * |
147 | */ | |
b9d10be7 | 148 | void cpu_hotplug_begin(void) |
d221938c | 149 | { |
87af9e7f | 150 | DEFINE_WAIT(wait); |
d2ba7e2a | 151 | |
87af9e7f | 152 | cpu_hotplug.active_writer = current; |
a19423b9 | 153 | cpuhp_lock_acquire(); |
87af9e7f | 154 | |
d2ba7e2a ON |
155 | for (;;) { |
156 | mutex_lock(&cpu_hotplug.lock); | |
87af9e7f DH |
157 | prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE); |
158 | if (likely(!atomic_read(&cpu_hotplug.refcount))) | |
159 | break; | |
d221938c GS |
160 | mutex_unlock(&cpu_hotplug.lock); |
161 | schedule(); | |
d221938c | 162 | } |
87af9e7f | 163 | finish_wait(&cpu_hotplug.wq, &wait); |
d221938c GS |
164 | } |
165 | ||
b9d10be7 | 166 | void cpu_hotplug_done(void) |
d221938c GS |
167 | { |
168 | cpu_hotplug.active_writer = NULL; | |
169 | mutex_unlock(&cpu_hotplug.lock); | |
a19423b9 | 170 | cpuhp_lock_release(); |
d221938c | 171 | } |
79a6cdeb | 172 | |
16e53dbf SB |
173 | /* |
174 | * Wait for currently running CPU hotplug operations to complete (if any) and | |
175 | * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects | |
176 | * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the | |
177 | * hotplug path before performing hotplug operations. So acquiring that lock | |
178 | * guarantees mutual exclusion from any currently running hotplug operations. | |
179 | */ | |
180 | void cpu_hotplug_disable(void) | |
181 | { | |
182 | cpu_maps_update_begin(); | |
89af7ba5 | 183 | cpu_hotplug_disabled++; |
16e53dbf SB |
184 | cpu_maps_update_done(); |
185 | } | |
32145c46 | 186 | EXPORT_SYMBOL_GPL(cpu_hotplug_disable); |
16e53dbf SB |
187 | |
188 | void cpu_hotplug_enable(void) | |
189 | { | |
190 | cpu_maps_update_begin(); | |
89af7ba5 | 191 | WARN_ON(--cpu_hotplug_disabled < 0); |
16e53dbf SB |
192 | cpu_maps_update_done(); |
193 | } | |
32145c46 | 194 | EXPORT_SYMBOL_GPL(cpu_hotplug_enable); |
b9d10be7 | 195 | #endif /* CONFIG_HOTPLUG_CPU */ |
79a6cdeb | 196 | |
1da177e4 | 197 | /* Need to know about CPUs going up/down? */ |
71cf5aee | 198 | int register_cpu_notifier(struct notifier_block *nb) |
1da177e4 | 199 | { |
bd5349cf | 200 | int ret; |
d221938c | 201 | cpu_maps_update_begin(); |
bd5349cf | 202 | ret = raw_notifier_chain_register(&cpu_chain, nb); |
d221938c | 203 | cpu_maps_update_done(); |
bd5349cf | 204 | return ret; |
1da177e4 | 205 | } |
65edc68c | 206 | |
71cf5aee | 207 | int __register_cpu_notifier(struct notifier_block *nb) |
93ae4f97 SB |
208 | { |
209 | return raw_notifier_chain_register(&cpu_chain, nb); | |
210 | } | |
211 | ||
090e77c3 | 212 | static int __cpu_notify(unsigned long val, unsigned int cpu, int nr_to_call, |
e9fb7631 AM |
213 | int *nr_calls) |
214 | { | |
090e77c3 TG |
215 | unsigned long mod = cpuhp_tasks_frozen ? CPU_TASKS_FROZEN : 0; |
216 | void *hcpu = (void *)(long)cpu; | |
217 | ||
e6bde73b AM |
218 | int ret; |
219 | ||
090e77c3 | 220 | ret = __raw_notifier_call_chain(&cpu_chain, val | mod, hcpu, nr_to_call, |
e9fb7631 | 221 | nr_calls); |
e6bde73b AM |
222 | |
223 | return notifier_to_errno(ret); | |
e9fb7631 AM |
224 | } |
225 | ||
090e77c3 | 226 | static int cpu_notify(unsigned long val, unsigned int cpu) |
e9fb7631 | 227 | { |
090e77c3 | 228 | return __cpu_notify(val, cpu, -1, NULL); |
e9fb7631 AM |
229 | } |
230 | ||
ba997462 TG |
231 | /* Notifier wrappers for transitioning to state machine */ |
232 | static int notify_prepare(unsigned int cpu) | |
233 | { | |
234 | int nr_calls = 0; | |
235 | int ret; | |
236 | ||
237 | ret = __cpu_notify(CPU_UP_PREPARE, cpu, -1, &nr_calls); | |
238 | if (ret) { | |
239 | nr_calls--; | |
240 | printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n", | |
241 | __func__, cpu); | |
242 | __cpu_notify(CPU_UP_CANCELED, cpu, nr_calls, NULL); | |
243 | } | |
244 | return ret; | |
245 | } | |
246 | ||
247 | static int notify_online(unsigned int cpu) | |
248 | { | |
249 | cpu_notify(CPU_ONLINE, cpu); | |
250 | return 0; | |
251 | } | |
252 | ||
253 | static int bringup_cpu(unsigned int cpu) | |
254 | { | |
255 | struct task_struct *idle = idle_thread_get(cpu); | |
256 | int ret; | |
257 | ||
258 | /* Arch-specific enabling code. */ | |
259 | ret = __cpu_up(cpu, idle); | |
260 | if (ret) { | |
261 | cpu_notify(CPU_UP_CANCELED, cpu); | |
262 | return ret; | |
263 | } | |
264 | BUG_ON(!cpu_online(cpu)); | |
265 | return 0; | |
266 | } | |
267 | ||
00b9b0af | 268 | #ifdef CONFIG_HOTPLUG_CPU |
1da177e4 | 269 | EXPORT_SYMBOL(register_cpu_notifier); |
93ae4f97 | 270 | EXPORT_SYMBOL(__register_cpu_notifier); |
1da177e4 | 271 | |
71cf5aee | 272 | void unregister_cpu_notifier(struct notifier_block *nb) |
1da177e4 | 273 | { |
d221938c | 274 | cpu_maps_update_begin(); |
bd5349cf | 275 | raw_notifier_chain_unregister(&cpu_chain, nb); |
d221938c | 276 | cpu_maps_update_done(); |
1da177e4 LT |
277 | } |
278 | EXPORT_SYMBOL(unregister_cpu_notifier); | |
279 | ||
71cf5aee | 280 | void __unregister_cpu_notifier(struct notifier_block *nb) |
93ae4f97 SB |
281 | { |
282 | raw_notifier_chain_unregister(&cpu_chain, nb); | |
283 | } | |
284 | EXPORT_SYMBOL(__unregister_cpu_notifier); | |
285 | ||
e4cc2f87 AV |
286 | /** |
287 | * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU | |
288 | * @cpu: a CPU id | |
289 | * | |
290 | * This function walks all processes, finds a valid mm struct for each one and | |
291 | * then clears a corresponding bit in mm's cpumask. While this all sounds | |
292 | * trivial, there are various non-obvious corner cases, which this function | |
293 | * tries to solve in a safe manner. | |
294 | * | |
295 | * Also note that the function uses a somewhat relaxed locking scheme, so it may | |
296 | * be called only for an already offlined CPU. | |
297 | */ | |
cb79295e AV |
298 | void clear_tasks_mm_cpumask(int cpu) |
299 | { | |
300 | struct task_struct *p; | |
301 | ||
302 | /* | |
303 | * This function is called after the cpu is taken down and marked | |
304 | * offline, so its not like new tasks will ever get this cpu set in | |
305 | * their mm mask. -- Peter Zijlstra | |
306 | * Thus, we may use rcu_read_lock() here, instead of grabbing | |
307 | * full-fledged tasklist_lock. | |
308 | */ | |
e4cc2f87 | 309 | WARN_ON(cpu_online(cpu)); |
cb79295e AV |
310 | rcu_read_lock(); |
311 | for_each_process(p) { | |
312 | struct task_struct *t; | |
313 | ||
e4cc2f87 AV |
314 | /* |
315 | * Main thread might exit, but other threads may still have | |
316 | * a valid mm. Find one. | |
317 | */ | |
cb79295e AV |
318 | t = find_lock_task_mm(p); |
319 | if (!t) | |
320 | continue; | |
321 | cpumask_clear_cpu(cpu, mm_cpumask(t->mm)); | |
322 | task_unlock(t); | |
323 | } | |
324 | rcu_read_unlock(); | |
325 | } | |
326 | ||
b728ca06 | 327 | static inline void check_for_tasks(int dead_cpu) |
1da177e4 | 328 | { |
b728ca06 | 329 | struct task_struct *g, *p; |
1da177e4 | 330 | |
a75a6068 ON |
331 | read_lock(&tasklist_lock); |
332 | for_each_process_thread(g, p) { | |
b728ca06 KT |
333 | if (!p->on_rq) |
334 | continue; | |
335 | /* | |
336 | * We do the check with unlocked task_rq(p)->lock. | |
337 | * Order the reading to do not warn about a task, | |
338 | * which was running on this cpu in the past, and | |
339 | * it's just been woken on another cpu. | |
340 | */ | |
341 | rmb(); | |
342 | if (task_cpu(p) != dead_cpu) | |
343 | continue; | |
344 | ||
345 | pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n", | |
346 | p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags); | |
a75a6068 ON |
347 | } |
348 | read_unlock(&tasklist_lock); | |
1da177e4 LT |
349 | } |
350 | ||
98458172 TG |
351 | static void cpu_notify_nofail(unsigned long val, unsigned int cpu) |
352 | { | |
353 | BUG_ON(cpu_notify(val, cpu)); | |
354 | } | |
355 | ||
356 | static int notify_down_prepare(unsigned int cpu) | |
357 | { | |
358 | int err, nr_calls = 0; | |
359 | ||
360 | err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls); | |
361 | if (err) { | |
362 | nr_calls--; | |
363 | __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL); | |
364 | pr_warn("%s: attempt to take down CPU %u failed\n", | |
365 | __func__, cpu); | |
366 | } | |
367 | return err; | |
368 | } | |
369 | ||
1da177e4 | 370 | /* Take this CPU down. */ |
71cf5aee | 371 | static int take_cpu_down(void *_param) |
1da177e4 | 372 | { |
090e77c3 | 373 | int err, cpu = smp_processor_id(); |
1da177e4 | 374 | |
1da177e4 LT |
375 | /* Ensure this CPU doesn't handle any more interrupts. */ |
376 | err = __cpu_disable(); | |
377 | if (err < 0) | |
f3705136 | 378 | return err; |
1da177e4 | 379 | |
090e77c3 | 380 | cpu_notify(CPU_DYING, cpu); |
52c063d1 TG |
381 | /* Give up timekeeping duties */ |
382 | tick_handover_do_timer(); | |
14e568e7 | 383 | /* Park the stopper thread */ |
090e77c3 | 384 | stop_machine_park(cpu); |
f3705136 | 385 | return 0; |
1da177e4 LT |
386 | } |
387 | ||
98458172 | 388 | static int takedown_cpu(unsigned int cpu) |
1da177e4 | 389 | { |
98458172 | 390 | int err; |
1da177e4 | 391 | |
6acce3ef PZ |
392 | /* |
393 | * By now we've cleared cpu_active_mask, wait for all preempt-disabled | |
394 | * and RCU users of this state to go away such that all new such users | |
395 | * will observe it. | |
396 | * | |
397 | * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might | |
779de6ce | 398 | * not imply sync_sched(), so wait for both. |
106dd5af M |
399 | * |
400 | * Do sync before park smpboot threads to take care the rcu boost case. | |
6acce3ef | 401 | */ |
779de6ce PM |
402 | if (IS_ENABLED(CONFIG_PREEMPT)) |
403 | synchronize_rcu_mult(call_rcu, call_rcu_sched); | |
404 | else | |
405 | synchronize_rcu(); | |
6acce3ef | 406 | |
106dd5af M |
407 | smpboot_park_threads(cpu); |
408 | ||
6acce3ef | 409 | /* |
a8994181 TG |
410 | * Prevent irq alloc/free while the dying cpu reorganizes the |
411 | * interrupt affinities. | |
6acce3ef | 412 | */ |
a8994181 | 413 | irq_lock_sparse(); |
6acce3ef | 414 | |
a8994181 TG |
415 | /* |
416 | * So now all preempt/rcu users must observe !cpu_active(). | |
417 | */ | |
090e77c3 | 418 | err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu)); |
04321587 | 419 | if (err) { |
1da177e4 | 420 | /* CPU didn't die: tell everyone. Can't complain. */ |
090e77c3 | 421 | cpu_notify_nofail(CPU_DOWN_FAILED, cpu); |
a8994181 | 422 | irq_unlock_sparse(); |
98458172 | 423 | return err; |
8fa1d7d3 | 424 | } |
04321587 | 425 | BUG_ON(cpu_online(cpu)); |
1da177e4 | 426 | |
48c5ccae PZ |
427 | /* |
428 | * The migration_call() CPU_DYING callback will have removed all | |
429 | * runnable tasks from the cpu, there's only the idle task left now | |
430 | * that the migration thread is done doing the stop_machine thing. | |
51a96c77 PZ |
431 | * |
432 | * Wait for the stop thread to go away. | |
48c5ccae | 433 | */ |
528a25b0 | 434 | while (!per_cpu(cpu_dead_idle, cpu)) |
51a96c77 | 435 | cpu_relax(); |
528a25b0 PM |
436 | smp_mb(); /* Read from cpu_dead_idle before __cpu_die(). */ |
437 | per_cpu(cpu_dead_idle, cpu) = false; | |
1da177e4 | 438 | |
a8994181 TG |
439 | /* Interrupts are moved away from the dying cpu, reenable alloc/free */ |
440 | irq_unlock_sparse(); | |
441 | ||
345527b1 | 442 | hotplug_cpu__broadcast_tick_pull(cpu); |
1da177e4 LT |
443 | /* This actually kills the CPU. */ |
444 | __cpu_die(cpu); | |
445 | ||
a49b116d | 446 | tick_cleanup_dead_cpu(cpu); |
98458172 TG |
447 | return 0; |
448 | } | |
1da177e4 | 449 | |
98458172 TG |
450 | static int notify_dead(unsigned int cpu) |
451 | { | |
452 | cpu_notify_nofail(CPU_DEAD, cpu); | |
1da177e4 | 453 | check_for_tasks(cpu); |
98458172 TG |
454 | return 0; |
455 | } | |
456 | ||
457 | /* Requires cpu_add_remove_lock to be held */ | |
458 | static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) | |
459 | { | |
460 | int err; | |
461 | ||
462 | if (num_online_cpus() == 1) | |
463 | return -EBUSY; | |
464 | ||
465 | if (!cpu_online(cpu)) | |
466 | return -EINVAL; | |
467 | ||
468 | cpu_hotplug_begin(); | |
469 | ||
470 | cpuhp_tasks_frozen = tasks_frozen; | |
471 | ||
472 | err = notify_down_prepare(cpu); | |
473 | if (err) | |
474 | goto out_release; | |
475 | err = takedown_cpu(cpu); | |
476 | if (err) | |
477 | goto out_release; | |
478 | ||
479 | notify_dead(cpu); | |
1da177e4 | 480 | |
baaca49f | 481 | out_release: |
d221938c | 482 | cpu_hotplug_done(); |
e9fb7631 | 483 | if (!err) |
090e77c3 | 484 | cpu_notify_nofail(CPU_POST_DEAD, cpu); |
e3920fb4 RW |
485 | return err; |
486 | } | |
487 | ||
71cf5aee | 488 | int cpu_down(unsigned int cpu) |
e3920fb4 | 489 | { |
9ea09af3 | 490 | int err; |
e3920fb4 | 491 | |
d221938c | 492 | cpu_maps_update_begin(); |
e761b772 MK |
493 | |
494 | if (cpu_hotplug_disabled) { | |
e3920fb4 | 495 | err = -EBUSY; |
e761b772 MK |
496 | goto out; |
497 | } | |
498 | ||
e761b772 | 499 | err = _cpu_down(cpu, 0); |
e3920fb4 | 500 | |
e761b772 | 501 | out: |
d221938c | 502 | cpu_maps_update_done(); |
1da177e4 LT |
503 | return err; |
504 | } | |
b62b8ef9 | 505 | EXPORT_SYMBOL(cpu_down); |
1da177e4 LT |
506 | #endif /*CONFIG_HOTPLUG_CPU*/ |
507 | ||
00df35f9 PM |
508 | /* |
509 | * Unpark per-CPU smpboot kthreads at CPU-online time. | |
510 | */ | |
511 | static int smpboot_thread_call(struct notifier_block *nfb, | |
512 | unsigned long action, void *hcpu) | |
513 | { | |
514 | int cpu = (long)hcpu; | |
515 | ||
516 | switch (action & ~CPU_TASKS_FROZEN) { | |
517 | ||
64eaf974 | 518 | case CPU_DOWN_FAILED: |
00df35f9 PM |
519 | case CPU_ONLINE: |
520 | smpboot_unpark_threads(cpu); | |
521 | break; | |
522 | ||
523 | default: | |
524 | break; | |
525 | } | |
526 | ||
527 | return NOTIFY_OK; | |
528 | } | |
529 | ||
530 | static struct notifier_block smpboot_thread_notifier = { | |
531 | .notifier_call = smpboot_thread_call, | |
532 | .priority = CPU_PRI_SMPBOOT, | |
533 | }; | |
534 | ||
927da9df | 535 | void smpboot_thread_init(void) |
00df35f9 PM |
536 | { |
537 | register_cpu_notifier(&smpboot_thread_notifier); | |
538 | } | |
539 | ||
e3920fb4 | 540 | /* Requires cpu_add_remove_lock to be held */ |
0db0628d | 541 | static int _cpu_up(unsigned int cpu, int tasks_frozen) |
1da177e4 | 542 | { |
3bb5d2ee | 543 | struct task_struct *idle; |
ba997462 | 544 | int ret; |
1da177e4 | 545 | |
d221938c | 546 | cpu_hotplug_begin(); |
38498a67 | 547 | |
5e5041f3 YI |
548 | if (cpu_online(cpu) || !cpu_present(cpu)) { |
549 | ret = -EINVAL; | |
550 | goto out; | |
551 | } | |
552 | ||
3bb5d2ee SS |
553 | idle = idle_thread_get(cpu); |
554 | if (IS_ERR(idle)) { | |
555 | ret = PTR_ERR(idle); | |
38498a67 | 556 | goto out; |
3bb5d2ee | 557 | } |
38498a67 | 558 | |
ba997462 TG |
559 | cpuhp_tasks_frozen = tasks_frozen; |
560 | ||
f97f8f06 TG |
561 | ret = smpboot_create_threads(cpu); |
562 | if (ret) | |
563 | goto out; | |
564 | ||
ba997462 TG |
565 | ret = notify_prepare(cpu); |
566 | if (ret) | |
567 | goto out; | |
1da177e4 | 568 | |
ba997462 TG |
569 | ret = bringup_cpu(cpu); |
570 | if (ret) | |
571 | goto out; | |
1da177e4 | 572 | |
ba997462 | 573 | notify_online(cpu); |
38498a67 | 574 | out: |
d221938c | 575 | cpu_hotplug_done(); |
e3920fb4 RW |
576 | |
577 | return ret; | |
578 | } | |
579 | ||
0db0628d | 580 | int cpu_up(unsigned int cpu) |
e3920fb4 RW |
581 | { |
582 | int err = 0; | |
cf23422b | 583 | |
e0b582ec | 584 | if (!cpu_possible(cpu)) { |
84117da5 FF |
585 | pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n", |
586 | cpu); | |
87d5e023 | 587 | #if defined(CONFIG_IA64) |
84117da5 | 588 | pr_err("please check additional_cpus= boot parameter\n"); |
73e753a5 KH |
589 | #endif |
590 | return -EINVAL; | |
591 | } | |
e3920fb4 | 592 | |
01b0f197 TK |
593 | err = try_online_node(cpu_to_node(cpu)); |
594 | if (err) | |
595 | return err; | |
cf23422b | 596 | |
d221938c | 597 | cpu_maps_update_begin(); |
e761b772 MK |
598 | |
599 | if (cpu_hotplug_disabled) { | |
e3920fb4 | 600 | err = -EBUSY; |
e761b772 MK |
601 | goto out; |
602 | } | |
603 | ||
604 | err = _cpu_up(cpu, 0); | |
605 | ||
e761b772 | 606 | out: |
d221938c | 607 | cpu_maps_update_done(); |
e3920fb4 RW |
608 | return err; |
609 | } | |
a513f6ba | 610 | EXPORT_SYMBOL_GPL(cpu_up); |
e3920fb4 | 611 | |
f3de4be9 | 612 | #ifdef CONFIG_PM_SLEEP_SMP |
e0b582ec | 613 | static cpumask_var_t frozen_cpus; |
e3920fb4 RW |
614 | |
615 | int disable_nonboot_cpus(void) | |
616 | { | |
e9a5f426 | 617 | int cpu, first_cpu, error = 0; |
e3920fb4 | 618 | |
d221938c | 619 | cpu_maps_update_begin(); |
e0b582ec | 620 | first_cpu = cpumask_first(cpu_online_mask); |
9ee349ad XF |
621 | /* |
622 | * We take down all of the non-boot CPUs in one shot to avoid races | |
e3920fb4 RW |
623 | * with the userspace trying to use the CPU hotplug at the same time |
624 | */ | |
e0b582ec | 625 | cpumask_clear(frozen_cpus); |
6ad4c188 | 626 | |
84117da5 | 627 | pr_info("Disabling non-boot CPUs ...\n"); |
e3920fb4 RW |
628 | for_each_online_cpu(cpu) { |
629 | if (cpu == first_cpu) | |
630 | continue; | |
bb3632c6 | 631 | trace_suspend_resume(TPS("CPU_OFF"), cpu, true); |
8bb78442 | 632 | error = _cpu_down(cpu, 1); |
bb3632c6 | 633 | trace_suspend_resume(TPS("CPU_OFF"), cpu, false); |
feae3203 | 634 | if (!error) |
e0b582ec | 635 | cpumask_set_cpu(cpu, frozen_cpus); |
feae3203 | 636 | else { |
84117da5 | 637 | pr_err("Error taking CPU%d down: %d\n", cpu, error); |
e3920fb4 RW |
638 | break; |
639 | } | |
640 | } | |
86886e55 | 641 | |
89af7ba5 | 642 | if (!error) |
e3920fb4 | 643 | BUG_ON(num_online_cpus() > 1); |
89af7ba5 | 644 | else |
84117da5 | 645 | pr_err("Non-boot CPUs are not disabled\n"); |
89af7ba5 VK |
646 | |
647 | /* | |
648 | * Make sure the CPUs won't be enabled by someone else. We need to do | |
649 | * this even in case of failure as all disable_nonboot_cpus() users are | |
650 | * supposed to do enable_nonboot_cpus() on the failure path. | |
651 | */ | |
652 | cpu_hotplug_disabled++; | |
653 | ||
d221938c | 654 | cpu_maps_update_done(); |
e3920fb4 RW |
655 | return error; |
656 | } | |
657 | ||
d0af9eed SS |
658 | void __weak arch_enable_nonboot_cpus_begin(void) |
659 | { | |
660 | } | |
661 | ||
662 | void __weak arch_enable_nonboot_cpus_end(void) | |
663 | { | |
664 | } | |
665 | ||
71cf5aee | 666 | void enable_nonboot_cpus(void) |
e3920fb4 RW |
667 | { |
668 | int cpu, error; | |
669 | ||
670 | /* Allow everyone to use the CPU hotplug again */ | |
d221938c | 671 | cpu_maps_update_begin(); |
89af7ba5 | 672 | WARN_ON(--cpu_hotplug_disabled < 0); |
e0b582ec | 673 | if (cpumask_empty(frozen_cpus)) |
1d64b9cb | 674 | goto out; |
e3920fb4 | 675 | |
84117da5 | 676 | pr_info("Enabling non-boot CPUs ...\n"); |
d0af9eed SS |
677 | |
678 | arch_enable_nonboot_cpus_begin(); | |
679 | ||
e0b582ec | 680 | for_each_cpu(cpu, frozen_cpus) { |
bb3632c6 | 681 | trace_suspend_resume(TPS("CPU_ON"), cpu, true); |
8bb78442 | 682 | error = _cpu_up(cpu, 1); |
bb3632c6 | 683 | trace_suspend_resume(TPS("CPU_ON"), cpu, false); |
e3920fb4 | 684 | if (!error) { |
84117da5 | 685 | pr_info("CPU%d is up\n", cpu); |
e3920fb4 RW |
686 | continue; |
687 | } | |
84117da5 | 688 | pr_warn("Error taking CPU%d up: %d\n", cpu, error); |
e3920fb4 | 689 | } |
d0af9eed SS |
690 | |
691 | arch_enable_nonboot_cpus_end(); | |
692 | ||
e0b582ec | 693 | cpumask_clear(frozen_cpus); |
1d64b9cb | 694 | out: |
d221938c | 695 | cpu_maps_update_done(); |
1da177e4 | 696 | } |
e0b582ec | 697 | |
d7268a31 | 698 | static int __init alloc_frozen_cpus(void) |
e0b582ec RR |
699 | { |
700 | if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO)) | |
701 | return -ENOMEM; | |
702 | return 0; | |
703 | } | |
704 | core_initcall(alloc_frozen_cpus); | |
79cfbdfa | 705 | |
79cfbdfa SB |
706 | /* |
707 | * When callbacks for CPU hotplug notifications are being executed, we must | |
708 | * ensure that the state of the system with respect to the tasks being frozen | |
709 | * or not, as reported by the notification, remains unchanged *throughout the | |
710 | * duration* of the execution of the callbacks. | |
711 | * Hence we need to prevent the freezer from racing with regular CPU hotplug. | |
712 | * | |
713 | * This synchronization is implemented by mutually excluding regular CPU | |
714 | * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/ | |
715 | * Hibernate notifications. | |
716 | */ | |
717 | static int | |
718 | cpu_hotplug_pm_callback(struct notifier_block *nb, | |
719 | unsigned long action, void *ptr) | |
720 | { | |
721 | switch (action) { | |
722 | ||
723 | case PM_SUSPEND_PREPARE: | |
724 | case PM_HIBERNATION_PREPARE: | |
16e53dbf | 725 | cpu_hotplug_disable(); |
79cfbdfa SB |
726 | break; |
727 | ||
728 | case PM_POST_SUSPEND: | |
729 | case PM_POST_HIBERNATION: | |
16e53dbf | 730 | cpu_hotplug_enable(); |
79cfbdfa SB |
731 | break; |
732 | ||
733 | default: | |
734 | return NOTIFY_DONE; | |
735 | } | |
736 | ||
737 | return NOTIFY_OK; | |
738 | } | |
739 | ||
740 | ||
d7268a31 | 741 | static int __init cpu_hotplug_pm_sync_init(void) |
79cfbdfa | 742 | { |
6e32d479 FY |
743 | /* |
744 | * cpu_hotplug_pm_callback has higher priority than x86 | |
745 | * bsp_pm_callback which depends on cpu_hotplug_pm_callback | |
746 | * to disable cpu hotplug to avoid cpu hotplug race. | |
747 | */ | |
79cfbdfa SB |
748 | pm_notifier(cpu_hotplug_pm_callback, 0); |
749 | return 0; | |
750 | } | |
751 | core_initcall(cpu_hotplug_pm_sync_init); | |
752 | ||
f3de4be9 | 753 | #endif /* CONFIG_PM_SLEEP_SMP */ |
68f4f1ec | 754 | |
e545a614 MS |
755 | /** |
756 | * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers | |
757 | * @cpu: cpu that just started | |
758 | * | |
759 | * This function calls the cpu_chain notifiers with CPU_STARTING. | |
760 | * It must be called by the arch code on the new cpu, before the new cpu | |
761 | * enables interrupts and before the "boot" cpu returns from __cpu_up(). | |
762 | */ | |
0db0628d | 763 | void notify_cpu_starting(unsigned int cpu) |
e545a614 | 764 | { |
090e77c3 | 765 | cpu_notify(CPU_STARTING, cpu); |
e545a614 MS |
766 | } |
767 | ||
68f4f1ec | 768 | #endif /* CONFIG_SMP */ |
b8d317d1 | 769 | |
e56b3bc7 LT |
770 | /* |
771 | * cpu_bit_bitmap[] is a special, "compressed" data structure that | |
772 | * represents all NR_CPUS bits binary values of 1<<nr. | |
773 | * | |
e0b582ec | 774 | * It is used by cpumask_of() to get a constant address to a CPU |
e56b3bc7 LT |
775 | * mask value that has a single bit set only. |
776 | */ | |
b8d317d1 | 777 | |
e56b3bc7 | 778 | /* cpu_bit_bitmap[0] is empty - so we can back into it */ |
4d51985e | 779 | #define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x)) |
e56b3bc7 LT |
780 | #define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1) |
781 | #define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2) | |
782 | #define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4) | |
b8d317d1 | 783 | |
e56b3bc7 LT |
784 | const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = { |
785 | ||
786 | MASK_DECLARE_8(0), MASK_DECLARE_8(8), | |
787 | MASK_DECLARE_8(16), MASK_DECLARE_8(24), | |
788 | #if BITS_PER_LONG > 32 | |
789 | MASK_DECLARE_8(32), MASK_DECLARE_8(40), | |
790 | MASK_DECLARE_8(48), MASK_DECLARE_8(56), | |
b8d317d1 MT |
791 | #endif |
792 | }; | |
e56b3bc7 | 793 | EXPORT_SYMBOL_GPL(cpu_bit_bitmap); |
2d3854a3 RR |
794 | |
795 | const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL; | |
796 | EXPORT_SYMBOL(cpu_all_bits); | |
b3199c02 RR |
797 | |
798 | #ifdef CONFIG_INIT_ALL_POSSIBLE | |
4b804c85 | 799 | struct cpumask __cpu_possible_mask __read_mostly |
c4c54dd1 | 800 | = {CPU_BITS_ALL}; |
b3199c02 | 801 | #else |
4b804c85 | 802 | struct cpumask __cpu_possible_mask __read_mostly; |
b3199c02 | 803 | #endif |
4b804c85 | 804 | EXPORT_SYMBOL(__cpu_possible_mask); |
b3199c02 | 805 | |
4b804c85 RV |
806 | struct cpumask __cpu_online_mask __read_mostly; |
807 | EXPORT_SYMBOL(__cpu_online_mask); | |
b3199c02 | 808 | |
4b804c85 RV |
809 | struct cpumask __cpu_present_mask __read_mostly; |
810 | EXPORT_SYMBOL(__cpu_present_mask); | |
b3199c02 | 811 | |
4b804c85 RV |
812 | struct cpumask __cpu_active_mask __read_mostly; |
813 | EXPORT_SYMBOL(__cpu_active_mask); | |
3fa41520 | 814 | |
3fa41520 RR |
815 | void init_cpu_present(const struct cpumask *src) |
816 | { | |
c4c54dd1 | 817 | cpumask_copy(&__cpu_present_mask, src); |
3fa41520 RR |
818 | } |
819 | ||
820 | void init_cpu_possible(const struct cpumask *src) | |
821 | { | |
c4c54dd1 | 822 | cpumask_copy(&__cpu_possible_mask, src); |
3fa41520 RR |
823 | } |
824 | ||
825 | void init_cpu_online(const struct cpumask *src) | |
826 | { | |
c4c54dd1 | 827 | cpumask_copy(&__cpu_online_mask, src); |
3fa41520 | 828 | } |