kernel/cpu.c

   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 }