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