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