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