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 <trace/events/power.h>
  24
  25 #include "smpboot.h"
  26
  27 #ifdef CONFIG_SMP
  28 /* Serializes the updates to cpu_online_mask, cpu_present_mask */
  29 static DEFINE_MUTEX(cpu_add_remove_lock);
  30
  31 /*
  32  * The following two APIs (cpu_maps_update_begin/done) must be used when
  33  * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
  34  * The APIs cpu_notifier_register_begin/done() must be used to protect CPU
  35  * hotplug callback (un)registration performed using __register_cpu_notifier()
  36  * or __unregister_cpu_notifier().
  37  */
  38 void cpu_maps_update_begin(void)
  39 {
  40         mutex_lock(&cpu_add_remove_lock);
  41 }
  42 EXPORT_SYMBOL(cpu_notifier_register_begin);
  43
  44 void cpu_maps_update_done(void)
  45 {
  46         mutex_unlock(&cpu_add_remove_lock);
  47 }
  48 EXPORT_SYMBOL(cpu_notifier_register_done);
  49
  50 static RAW_NOTIFIER_HEAD(cpu_chain);
  51
  52 /* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
  53  * Should always be manipulated under cpu_add_remove_lock
  54  */
  55 static int cpu_hotplug_disabled;
  56
  57 #ifdef CONFIG_HOTPLUG_CPU
  58
  59 static struct {
  60         struct task_struct *active_writer;
  61         struct mutex lock; /* Synchronizes accesses to refcount, */
  62         /*
  63          * Also blocks the new readers during
  64          * an ongoing cpu hotplug operation.
  65          */
  66         int refcount;
  67         /* And allows lockless put_online_cpus(). */
  68         atomic_t puts_pending;
  69
  70 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  71         struct lockdep_map dep_map;
  72 #endif
  73 } cpu_hotplug = {
  74         .active_writer = NULL,
  75         .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
  76         .refcount = 0,
  77 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  78         .dep_map = {.name = "cpu_hotplug.lock" },
  79 #endif
  80 };
  81
  82 /* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
  83 #define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
  84 #define cpuhp_lock_acquire_tryread() \
  85                                   lock_map_acquire_tryread(&cpu_hotplug.dep_map)
  86 #define cpuhp_lock_acquire()      lock_map_acquire(&cpu_hotplug.dep_map)
  87 #define cpuhp_lock_release()      lock_map_release(&cpu_hotplug.dep_map)
  88
  89 static void apply_puts_pending(int max)
  90 {
  91         int delta;
  92
  93         if (atomic_read(&cpu_hotplug.puts_pending) >= max) {
  94                 delta = atomic_xchg(&cpu_hotplug.puts_pending, 0);
  95                 cpu_hotplug.refcount -= delta;
  96         }
  97 }
  98
  99 void get_online_cpus(void)
 100 {
 101         might_sleep();
 102         if (cpu_hotplug.active_writer == current)
 103                 return;
 104         cpuhp_lock_acquire_read();
 105         mutex_lock(&cpu_hotplug.lock);
 106         apply_puts_pending(65536);
 107         cpu_hotplug.refcount++;
 108         mutex_unlock(&cpu_hotplug.lock);
 109 }
 110 EXPORT_SYMBOL_GPL(get_online_cpus);
 111
 112 bool try_get_online_cpus(void)
 113 {
 114         if (cpu_hotplug.active_writer == current)
 115                 return true;
 116         if (!mutex_trylock(&cpu_hotplug.lock))
 117                 return false;
 118         cpuhp_lock_acquire_tryread();
 119         apply_puts_pending(65536);
 120         cpu_hotplug.refcount++;
 121         mutex_unlock(&cpu_hotplug.lock);
 122         return true;
 123 }
 124 EXPORT_SYMBOL_GPL(try_get_online_cpus);
 125
 126 void put_online_cpus(void)
 127 {
 128         if (cpu_hotplug.active_writer == current)
 129                 return;
 130         if (!mutex_trylock(&cpu_hotplug.lock)) {
 131                 atomic_inc(&cpu_hotplug.puts_pending);
 132                 cpuhp_lock_release();
 133                 return;
 134         }
 135
 136         if (WARN_ON(!cpu_hotplug.refcount))
 137                 cpu_hotplug.refcount++; /* try to fix things up */
 138
 139         if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
 140                 wake_up_process(cpu_hotplug.active_writer);
 141         mutex_unlock(&cpu_hotplug.lock);
 142         cpuhp_lock_release();
 143
 144 }
 145 EXPORT_SYMBOL_GPL(put_online_cpus);
 146
 147 /*
 148  * This ensures that the hotplug operation can begin only when the
 149  * refcount goes to zero.
 150  *
 151  * Note that during a cpu-hotplug operation, the new readers, if any,
 152  * will be blocked by the cpu_hotplug.lock
 153  *
 154  * Since cpu_hotplug_begin() is always called after invoking
 155  * cpu_maps_update_begin(), we can be sure that only one writer is active.
 156  *
 157  * Note that theoretically, there is a possibility of a livelock:
 158  * - Refcount goes to zero, last reader wakes up the sleeping
 159  *   writer.
 160  * - Last reader unlocks the cpu_hotplug.lock.
 161  * - A new reader arrives at this moment, bumps up the refcount.
 162  * - The writer acquires the cpu_hotplug.lock finds the refcount
 163  *   non zero and goes to sleep again.
 164  *
 165  * However, this is very difficult to achieve in practice since
 166  * get_online_cpus() not an api which is called all that often.
 167  *
 168  */
 169 void cpu_hotplug_begin(void)
 170 {
 171         cpu_hotplug.active_writer = current;
 172
 173         cpuhp_lock_acquire();
 174         for (;;) {
 175                 mutex_lock(&cpu_hotplug.lock);
 176                 apply_puts_pending(1);
 177                 if (likely(!cpu_hotplug.refcount))
 178                         break;
 179                 __set_current_state(TASK_UNINTERRUPTIBLE);
 180                 mutex_unlock(&cpu_hotplug.lock);
 181                 schedule();
 182         }
 183 }
 184
 185 void cpu_hotplug_done(void)
 186 {
 187         cpu_hotplug.active_writer = NULL;
 188         mutex_unlock(&cpu_hotplug.lock);
 189         cpuhp_lock_release();
 190 }
 191
 192 /*
 193  * Wait for currently running CPU hotplug operations to complete (if any) and
 194  * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
 195  * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
 196  * hotplug path before performing hotplug operations. So acquiring that lock
 197  * guarantees mutual exclusion from any currently running hotplug operations.
 198  */
 199 void cpu_hotplug_disable(void)
 200 {
 201         cpu_maps_update_begin();
 202         cpu_hotplug_disabled = 1;
 203         cpu_maps_update_done();
 204 }
 205
 206 void cpu_hotplug_enable(void)
 207 {
 208         cpu_maps_update_begin();
 209         cpu_hotplug_disabled = 0;
 210         cpu_maps_update_done();
 211 }
 212
 213 #endif  /* CONFIG_HOTPLUG_CPU */
 214
 215 /* Need to know about CPUs going up/down? */
 216 int __ref register_cpu_notifier(struct notifier_block *nb)
 217 {
 218         int ret;
 219         cpu_maps_update_begin();
 220         ret = raw_notifier_chain_register(&cpu_chain, nb);
 221         cpu_maps_update_done();
 222         return ret;
 223 }
 224
 225 int __ref __register_cpu_notifier(struct notifier_block *nb)
 226 {
 227         return raw_notifier_chain_register(&cpu_chain, nb);
 228 }
 229
 230 static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
 231                         int *nr_calls)
 232 {
 233         int ret;
 234
 235         ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
 236                                         nr_calls);
 237
 238         return notifier_to_errno(ret);
 239 }
 240
 241 static int cpu_notify(unsigned long val, void *v)
 242 {
 243         return __cpu_notify(val, v, -1, NULL);
 244 }
 245
 246 #ifdef CONFIG_HOTPLUG_CPU
 247
 248 static void cpu_notify_nofail(unsigned long val, void *v)
 249 {
 250         BUG_ON(cpu_notify(val, v));
 251 }
 252 EXPORT_SYMBOL(register_cpu_notifier);
 253 EXPORT_SYMBOL(__register_cpu_notifier);
 254
 255 void __ref unregister_cpu_notifier(struct notifier_block *nb)
 256 {
 257         cpu_maps_update_begin();
 258         raw_notifier_chain_unregister(&cpu_chain, nb);
 259         cpu_maps_update_done();
 260 }
 261 EXPORT_SYMBOL(unregister_cpu_notifier);
 262
 263 void __ref __unregister_cpu_notifier(struct notifier_block *nb)
 264 {
 265         raw_notifier_chain_unregister(&cpu_chain, nb);
 266 }
 267 EXPORT_SYMBOL(__unregister_cpu_notifier);
 268
 269 /**
 270  * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
 271  * @cpu: a CPU id
 272  *
 273  * This function walks all processes, finds a valid mm struct for each one and
 274  * then clears a corresponding bit in mm's cpumask.  While this all sounds
 275  * trivial, there are various non-obvious corner cases, which this function
 276  * tries to solve in a safe manner.
 277  *
 278  * Also note that the function uses a somewhat relaxed locking scheme, so it may
 279  * be called only for an already offlined CPU.
 280  */
 281 void clear_tasks_mm_cpumask(int cpu)
 282 {
 283         struct task_struct *p;
 284
 285         /*
 286          * This function is called after the cpu is taken down and marked
 287          * offline, so its not like new tasks will ever get this cpu set in
 288          * their mm mask. -- Peter Zijlstra
 289          * Thus, we may use rcu_read_lock() here, instead of grabbing
 290          * full-fledged tasklist_lock.
 291          */
 292         WARN_ON(cpu_online(cpu));
 293         rcu_read_lock();
 294         for_each_process(p) {
 295                 struct task_struct *t;
 296
 297                 /*
 298                  * Main thread might exit, but other threads may still have
 299                  * a valid mm. Find one.
 300                  */
 301                 t = find_lock_task_mm(p);
 302                 if (!t)
 303                         continue;
 304                 cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
 305                 task_unlock(t);
 306         }
 307         rcu_read_unlock();
 308 }
 309
 310 static inline void check_for_tasks(int dead_cpu)
 311 {
 312         struct task_struct *g, *p;
 313
 314         read_lock_irq(&tasklist_lock);
 315         do_each_thread(g, p) {
 316                 if (!p->on_rq)
 317                         continue;
 318                 /*
 319                  * We do the check with unlocked task_rq(p)->lock.
 320                  * Order the reading to do not warn about a task,
 321                  * which was running on this cpu in the past, and
 322                  * it's just been woken on another cpu.
 323                  */
 324                 rmb();
 325                 if (task_cpu(p) != dead_cpu)
 326                         continue;
 327
 328                 pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
 329                         p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
 330         } while_each_thread(g, p);
 331         read_unlock_irq(&tasklist_lock);
 332 }
 333
 334 struct take_cpu_down_param {
 335         unsigned long mod;
 336         void *hcpu;
 337 };
 338
 339 /* Take this CPU down. */
 340 static int __ref take_cpu_down(void *_param)
 341 {
 342         struct take_cpu_down_param *param = _param;
 343         int err;
 344
 345         /* Ensure this CPU doesn't handle any more interrupts. */
 346         err = __cpu_disable();
 347         if (err < 0)
 348                 return err;
 349
 350         cpu_notify(CPU_DYING | param->mod, param->hcpu);
 351         /* Park the stopper thread */
 352         kthread_park(current);
 353         return 0;
 354 }
 355
 356 /* Requires cpu_add_remove_lock to be held */
 357 static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
 358 {
 359         int err, nr_calls = 0;
 360         void *hcpu = (void *)(long)cpu;
 361         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
 362         struct take_cpu_down_param tcd_param = {
 363                 .mod = mod,
 364                 .hcpu = hcpu,
 365         };
 366
 367         if (num_online_cpus() == 1)
 368                 return -EBUSY;
 369
 370         if (!cpu_online(cpu))
 371                 return -EINVAL;
 372
 373         cpu_hotplug_begin();
 374
 375         err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
 376         if (err) {
 377                 nr_calls--;
 378                 __cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
 379                 pr_warn("%s: attempt to take down CPU %u failed\n",
 380                         __func__, cpu);
 381                 goto out_release;
 382         }
 383
 384         /*
 385          * By now we've cleared cpu_active_mask, wait for all preempt-disabled
 386          * and RCU users of this state to go away such that all new such users
 387          * will observe it.
 388          *
 389          * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
 390          * not imply sync_sched(), so explicitly call both.
 391          *
 392          * Do sync before park smpboot threads to take care the rcu boost case.
 393          */
 394 #ifdef CONFIG_PREEMPT
 395         synchronize_sched();
 396 #endif
 397         synchronize_rcu();
 398
 399         smpboot_park_threads(cpu);
 400
 401         /*
 402          * So now all preempt/rcu users must observe !cpu_active().
 403          */
 404
 405         err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
 406         if (err) {
 407                 /* CPU didn't die: tell everyone.  Can't complain. */
 408                 smpboot_unpark_threads(cpu);
 409                 cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
 410                 goto out_release;
 411         }
 412         BUG_ON(cpu_online(cpu));
 413
 414         /*
 415          * The migration_call() CPU_DYING callback will have removed all
 416          * runnable tasks from the cpu, there's only the idle task left now
 417          * that the migration thread is done doing the stop_machine thing.
 418          *
 419          * Wait for the stop thread to go away.
 420          */
 421         while (!idle_cpu(cpu))
 422                 cpu_relax();
 423
 424         /* This actually kills the CPU. */
 425         __cpu_die(cpu);
 426
 427         /* CPU is completely dead: tell everyone.  Too late to complain. */
 428         cpu_notify_nofail(CPU_DEAD | mod, hcpu);
 429
 430         check_for_tasks(cpu);
 431
 432 out_release:
 433         cpu_hotplug_done();
 434         if (!err)
 435                 cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
 436         return err;
 437 }
 438
 439 int __ref cpu_down(unsigned int cpu)
 440 {
 441         int err;
 442
 443         cpu_maps_update_begin();
 444
 445         if (cpu_hotplug_disabled) {
 446                 err = -EBUSY;
 447                 goto out;
 448         }
 449
 450         err = _cpu_down(cpu, 0);
 451
 452 out:
 453         cpu_maps_update_done();
 454         return err;
 455 }
 456 EXPORT_SYMBOL(cpu_down);
 457 #endif /*CONFIG_HOTPLUG_CPU*/
 458
 459 /* Requires cpu_add_remove_lock to be held */
 460 static int _cpu_up(unsigned int cpu, int tasks_frozen)
 461 {
 462         int ret, nr_calls = 0;
 463         void *hcpu = (void *)(long)cpu;
 464         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
 465         struct task_struct *idle;
 466
 467         cpu_hotplug_begin();
 468
 469         if (cpu_online(cpu) || !cpu_present(cpu)) {
 470                 ret = -EINVAL;
 471                 goto out;
 472         }
 473
 474         idle = idle_thread_get(cpu);
 475         if (IS_ERR(idle)) {
 476                 ret = PTR_ERR(idle);
 477                 goto out;
 478         }
 479
 480         ret = smpboot_create_threads(cpu);
 481         if (ret)
 482                 goto out;
 483
 484         ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
 485         if (ret) {
 486                 nr_calls--;
 487                 pr_warn("%s: attempt to bring up CPU %u failed\n",
 488                         __func__, cpu);
 489                 goto out_notify;
 490         }
 491
 492         /* Arch-specific enabling code. */
 493         ret = __cpu_up(cpu, idle);
 494         if (ret != 0)
 495                 goto out_notify;
 496         BUG_ON(!cpu_online(cpu));
 497
 498         /* Wake the per cpu threads */
 499         smpboot_unpark_threads(cpu);
 500
 501         /* Now call notifier in preparation. */
 502         cpu_notify(CPU_ONLINE | mod, hcpu);
 503
 504 out_notify:
 505         if (ret != 0)
 506                 __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 507 out:
 508         cpu_hotplug_done();
 509
 510         return ret;
 511 }
 512
 513 int cpu_up(unsigned int cpu)
 514 {
 515         int err = 0;
 516
 517         if (!cpu_possible(cpu)) {
 518                 pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
 519                        cpu);
 520 #if defined(CONFIG_IA64)
 521                 pr_err("please check additional_cpus= boot parameter\n");
 522 #endif
 523                 return -EINVAL;
 524         }
 525
 526         err = try_online_node(cpu_to_node(cpu));
 527         if (err)
 528                 return err;
 529
 530         cpu_maps_update_begin();
 531
 532         if (cpu_hotplug_disabled) {
 533                 err = -EBUSY;
 534                 goto out;
 535         }
 536
 537         err = _cpu_up(cpu, 0);
 538
 539 out:
 540         cpu_maps_update_done();
 541         return err;
 542 }
 543 EXPORT_SYMBOL_GPL(cpu_up);
 544
 545 #ifdef CONFIG_PM_SLEEP_SMP
 546 static cpumask_var_t frozen_cpus;
 547
 548 int disable_nonboot_cpus(void)
 549 {
 550         int cpu, first_cpu, error = 0;
 551
 552         cpu_maps_update_begin();
 553         first_cpu = cpumask_first(cpu_online_mask);
 554         /*
 555          * We take down all of the non-boot CPUs in one shot to avoid races
 556          * with the userspace trying to use the CPU hotplug at the same time
 557          */
 558         cpumask_clear(frozen_cpus);
 559
 560         pr_info("Disabling non-boot CPUs ...\n");
 561         for_each_online_cpu(cpu) {
 562                 if (cpu == first_cpu)
 563                         continue;
 564                 trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
 565                 error = _cpu_down(cpu, 1);
 566                 trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
 567                 if (!error)
 568                         cpumask_set_cpu(cpu, frozen_cpus);
 569                 else {
 570                         pr_err("Error taking CPU%d down: %d\n", cpu, error);
 571                         break;
 572                 }
 573         }
 574
 575         if (!error) {
 576                 BUG_ON(num_online_cpus() > 1);
 577                 /* Make sure the CPUs won't be enabled by someone else */
 578                 cpu_hotplug_disabled = 1;
 579         } else {
 580                 pr_err("Non-boot CPUs are not disabled\n");
 581         }
 582         cpu_maps_update_done();
 583         return error;
 584 }
 585
 586 void __weak arch_enable_nonboot_cpus_begin(void)
 587 {
 588 }
 589
 590 void __weak arch_enable_nonboot_cpus_end(void)
 591 {
 592 }
 593
 594 void __ref enable_nonboot_cpus(void)
 595 {
 596         int cpu, error;
 597
 598         /* Allow everyone to use the CPU hotplug again */
 599         cpu_maps_update_begin();
 600         cpu_hotplug_disabled = 0;
 601         if (cpumask_empty(frozen_cpus))
 602                 goto out;
 603
 604         pr_info("Enabling non-boot CPUs ...\n");
 605
 606         arch_enable_nonboot_cpus_begin();
 607
 608         for_each_cpu(cpu, frozen_cpus) {
 609                 trace_suspend_resume(TPS("CPU_ON"), cpu, true);
 610                 error = _cpu_up(cpu, 1);
 611                 trace_suspend_resume(TPS("CPU_ON"), cpu, false);
 612                 if (!error) {
 613                         pr_info("CPU%d is up\n", cpu);
 614                         continue;
 615                 }
 616                 pr_warn("Error taking CPU%d up: %d\n", cpu, error);
 617         }
 618
 619         arch_enable_nonboot_cpus_end();
 620
 621         cpumask_clear(frozen_cpus);
 622 out:
 623         cpu_maps_update_done();
 624 }
 625
 626 static int __init alloc_frozen_cpus(void)
 627 {
 628         if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
 629                 return -ENOMEM;
 630         return 0;
 631 }
 632 core_initcall(alloc_frozen_cpus);
 633
 634 /*
 635  * When callbacks for CPU hotplug notifications are being executed, we must
 636  * ensure that the state of the system with respect to the tasks being frozen
 637  * or not, as reported by the notification, remains unchanged *throughout the
 638  * duration* of the execution of the callbacks.
 639  * Hence we need to prevent the freezer from racing with regular CPU hotplug.
 640  *
 641  * This synchronization is implemented by mutually excluding regular CPU
 642  * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
 643  * Hibernate notifications.
 644  */
 645 static int
 646 cpu_hotplug_pm_callback(struct notifier_block *nb,
 647                         unsigned long action, void *ptr)
 648 {
 649         switch (action) {
 650
 651         case PM_SUSPEND_PREPARE:
 652         case PM_HIBERNATION_PREPARE:
 653                 cpu_hotplug_disable();
 654                 break;
 655
 656         case PM_POST_SUSPEND:
 657         case PM_POST_HIBERNATION:
 658                 cpu_hotplug_enable();
 659                 break;
 660
 661         default:
 662                 return NOTIFY_DONE;
 663         }
 664
 665         return NOTIFY_OK;
 666 }
 667
 668
 669 static int __init cpu_hotplug_pm_sync_init(void)
 670 {
 671         /*
 672          * cpu_hotplug_pm_callback has higher priority than x86
 673          * bsp_pm_callback which depends on cpu_hotplug_pm_callback
 674          * to disable cpu hotplug to avoid cpu hotplug race.
 675          */
 676         pm_notifier(cpu_hotplug_pm_callback, 0);
 677         return 0;
 678 }
 679 core_initcall(cpu_hotplug_pm_sync_init);
 680
 681 #endif /* CONFIG_PM_SLEEP_SMP */
 682
 683 /**
 684  * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
 685  * @cpu: cpu that just started
 686  *
 687  * This function calls the cpu_chain notifiers with CPU_STARTING.
 688  * It must be called by the arch code on the new cpu, before the new cpu
 689  * enables interrupts and before the "boot" cpu returns from __cpu_up().
 690  */
 691 void notify_cpu_starting(unsigned int cpu)
 692 {
 693         unsigned long val = CPU_STARTING;
 694
 695 #ifdef CONFIG_PM_SLEEP_SMP
 696         if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
 697                 val = CPU_STARTING_FROZEN;
 698 #endif /* CONFIG_PM_SLEEP_SMP */
 699         cpu_notify(val, (void *)(long)cpu);
 700 }
 701
 702 #endif /* CONFIG_SMP */
 703
 704 /*
 705  * cpu_bit_bitmap[] is a special, "compressed" data structure that
 706  * represents all NR_CPUS bits binary values of 1<<nr.
 707  *
 708  * It is used by cpumask_of() to get a constant address to a CPU
 709  * mask value that has a single bit set only.
 710  */
 711
 712 /* cpu_bit_bitmap[0] is empty - so we can back into it */
 713 #define MASK_DECLARE_1(x)       [x+1][0] = (1UL << (x))
 714 #define MASK_DECLARE_2(x)       MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
 715 #define MASK_DECLARE_4(x)       MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
 716 #define MASK_DECLARE_8(x)       MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
 717
 718 const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
 719
 720         MASK_DECLARE_8(0),      MASK_DECLARE_8(8),
 721         MASK_DECLARE_8(16),     MASK_DECLARE_8(24),
 722 #if BITS_PER_LONG > 32
 723         MASK_DECLARE_8(32),     MASK_DECLARE_8(40),
 724         MASK_DECLARE_8(48),     MASK_DECLARE_8(56),
 725 #endif
 726 };
 727 EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
 728
 729 const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
 730 EXPORT_SYMBOL(cpu_all_bits);
 731
 732 #ifdef CONFIG_INIT_ALL_POSSIBLE
 733 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
 734         = CPU_BITS_ALL;
 735 #else
 736 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
 737 #endif
 738 const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
 739 EXPORT_SYMBOL(cpu_possible_mask);
 740
 741 static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
 742 const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
 743 EXPORT_SYMBOL(cpu_online_mask);
 744
 745 static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
 746 const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
 747 EXPORT_SYMBOL(cpu_present_mask);
 748
 749 static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
 750 const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
 751 EXPORT_SYMBOL(cpu_active_mask);
 752
 753 void set_cpu_possible(unsigned int cpu, bool possible)
 754 {
 755         if (possible)
 756                 cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
 757         else
 758                 cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
 759 }
 760
 761 void set_cpu_present(unsigned int cpu, bool present)
 762 {
 763         if (present)
 764                 cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
 765         else
 766                 cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
 767 }
 768
 769 void set_cpu_online(unsigned int cpu, bool online)
 770 {
 771         if (online) {
 772                 cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
 773                 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
 774         } else {
 775                 cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
 776         }
 777 }
 778
 779 void set_cpu_active(unsigned int cpu, bool active)
 780 {
 781         if (active)
 782                 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
 783         else
 784                 cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
 785 }
 786
 787 void init_cpu_present(const struct cpumask *src)
 788 {
 789         cpumask_copy(to_cpumask(cpu_present_bits), src);
 790 }
 791
 792 void init_cpu_possible(const struct cpumask *src)
 793 {
 794         cpumask_copy(to_cpumask(cpu_possible_bits), src);
 795 }
 796
 797 void init_cpu_online(const struct cpumask *src)
 798 {
 799         cpumask_copy(to_cpumask(cpu_online_bits), src);
 800 }