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         smpboot_park_threads(cpu);
 284
 285         err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
 286         if (err) {
 287                 /* CPU didn't die: tell everyone.  Can't complain. */
 288                 smpboot_unpark_threads(cpu);
 289                 cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
 290                 goto out_release;
 291         }
 292         BUG_ON(cpu_online(cpu));
 293
 294         /*
 295          * The migration_call() CPU_DYING callback will have removed all
 296          * runnable tasks from the cpu, there's only the idle task left now
 297          * that the migration thread is done doing the stop_machine thing.
 298          *
 299          * Wait for the stop thread to go away.
 300          */
 301         while (!idle_cpu(cpu))
 302                 cpu_relax();
 303
 304         /* This actually kills the CPU. */
 305         __cpu_die(cpu);
 306
 307         /* CPU is completely dead: tell everyone.  Too late to complain. */
 308         cpu_notify_nofail(CPU_DEAD | mod, hcpu);
 309
 310         check_for_tasks(cpu);
 311
 312 out_release:
 313         cpu_hotplug_done();
 314         if (!err)
 315                 cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
 316         return err;
 317 }
 318
 319 int __ref cpu_down(unsigned int cpu)
 320 {
 321         int err;
 322
 323         cpu_maps_update_begin();
 324
 325         if (cpu_hotplug_disabled) {
 326                 err = -EBUSY;
 327                 goto out;
 328         }
 329
 330         err = _cpu_down(cpu, 0);
 331
 332 out:
 333         cpu_maps_update_done();
 334         return err;
 335 }
 336 EXPORT_SYMBOL(cpu_down);
 337 #endif /*CONFIG_HOTPLUG_CPU*/
 338
 339 /* Requires cpu_add_remove_lock to be held */
 340 static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
 341 {
 342         int ret, nr_calls = 0;
 343         void *hcpu = (void *)(long)cpu;
 344         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
 345         struct task_struct *idle;
 346
 347         if (cpu_online(cpu) || !cpu_present(cpu))
 348                 return -EINVAL;
 349
 350         cpu_hotplug_begin();
 351
 352         idle = idle_thread_get(cpu);
 353         if (IS_ERR(idle)) {
 354                 ret = PTR_ERR(idle);
 355                 goto out;
 356         }
 357
 358         ret = smpboot_create_threads(cpu);
 359         if (ret)
 360                 goto out;
 361
 362         ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
 363         if (ret) {
 364                 nr_calls--;
 365                 printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
 366                                 __func__, cpu);
 367                 goto out_notify;
 368         }
 369
 370         /* Arch-specific enabling code. */
 371         ret = __cpu_up(cpu, idle);
 372         if (ret != 0)
 373                 goto out_notify;
 374         BUG_ON(!cpu_online(cpu));
 375
 376         /* Wake the per cpu threads */
 377         smpboot_unpark_threads(cpu);
 378
 379         /* Now call notifier in preparation. */
 380         cpu_notify(CPU_ONLINE | mod, hcpu);
 381
 382 out_notify:
 383         if (ret != 0)
 384                 __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 385 out:
 386         cpu_hotplug_done();
 387
 388         return ret;
 389 }
 390
 391 int __cpuinit cpu_up(unsigned int cpu)
 392 {
 393         int err = 0;
 394
 395 #ifdef  CONFIG_MEMORY_HOTPLUG
 396         int nid;
 397         pg_data_t       *pgdat;
 398 #endif
 399
 400         if (!cpu_possible(cpu)) {
 401                 printk(KERN_ERR "can't online cpu %d because it is not "
 402                         "configured as may-hotadd at boot time\n", cpu);
 403 #if defined(CONFIG_IA64)
 404                 printk(KERN_ERR "please check additional_cpus= boot "
 405                                 "parameter\n");
 406 #endif
 407                 return -EINVAL;
 408         }
 409
 410 #ifdef  CONFIG_MEMORY_HOTPLUG
 411         nid = cpu_to_node(cpu);
 412         if (!node_online(nid)) {
 413                 err = mem_online_node(nid);
 414                 if (err)
 415                         return err;
 416         }
 417
 418         pgdat = NODE_DATA(nid);
 419         if (!pgdat) {
 420                 printk(KERN_ERR
 421                         "Can't online cpu %d due to NULL pgdat\n", cpu);
 422                 return -ENOMEM;
 423         }
 424
 425         if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
 426                 mutex_lock(&zonelists_mutex);
 427                 build_all_zonelists(NULL, NULL);
 428                 mutex_unlock(&zonelists_mutex);
 429         }
 430 #endif
 431
 432         cpu_maps_update_begin();
 433
 434         if (cpu_hotplug_disabled) {
 435                 err = -EBUSY;
 436                 goto out;
 437         }
 438
 439         err = _cpu_up(cpu, 0);
 440
 441 out:
 442         cpu_maps_update_done();
 443         return err;
 444 }
 445 EXPORT_SYMBOL_GPL(cpu_up);
 446
 447 #ifdef CONFIG_PM_SLEEP_SMP
 448 static cpumask_var_t frozen_cpus;
 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
 462         printk("Disabling non-boot CPUs ...\n");
 463         for_each_online_cpu(cpu) {
 464                 if (cpu == first_cpu)
 465                         continue;
 466                 error = _cpu_down(cpu, 1);
 467                 if (!error)
 468                         cpumask_set_cpu(cpu, frozen_cpus);
 469                 else {
 470                         printk(KERN_ERR "Error taking CPU%d down: %d\n",
 471                                 cpu, error);
 472                         break;
 473                 }
 474         }
 475
 476         if (!error) {
 477                 BUG_ON(num_online_cpus() > 1);
 478                 /* Make sure the CPUs won't be enabled by someone else */
 479                 cpu_hotplug_disabled = 1;
 480         } else {
 481                 printk(KERN_ERR "Non-boot CPUs are not disabled\n");
 482         }
 483         cpu_maps_update_done();
 484         return error;
 485 }
 486
 487 void __weak arch_enable_nonboot_cpus_begin(void)
 488 {
 489 }
 490
 491 void __weak arch_enable_nonboot_cpus_end(void)
 492 {
 493 }
 494
 495 void __ref enable_nonboot_cpus(void)
 496 {
 497         int cpu, error;
 498
 499         /* Allow everyone to use the CPU hotplug again */
 500         cpu_maps_update_begin();
 501         cpu_hotplug_disabled = 0;
 502         if (cpumask_empty(frozen_cpus))
 503                 goto out;
 504
 505         printk(KERN_INFO "Enabling non-boot CPUs ...\n");
 506
 507         arch_enable_nonboot_cpus_begin();
 508
 509         for_each_cpu(cpu, frozen_cpus) {
 510                 error = _cpu_up(cpu, 1);
 511                 if (!error) {
 512                         printk(KERN_INFO "CPU%d is up\n", cpu);
 513                         continue;
 514                 }
 515                 printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
 516         }
 517
 518         arch_enable_nonboot_cpus_end();
 519
 520         cpumask_clear(frozen_cpus);
 521 out:
 522         cpu_maps_update_done();
 523 }
 524
 525 static int __init alloc_frozen_cpus(void)
 526 {
 527         if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
 528                 return -ENOMEM;
 529         return 0;
 530 }
 531 core_initcall(alloc_frozen_cpus);
 532
 533 /*
 534  * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
 535  * hotplug when tasks are about to be frozen. Also, don't allow the freezer
 536  * to continue until any currently running CPU hotplug operation gets
 537  * completed.
 538  * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
 539  * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
 540  * CPU hotplug path and released only after it is complete. Thus, we
 541  * (and hence the freezer) will block here until any currently running CPU
 542  * hotplug operation gets completed.
 543  */
 544 void cpu_hotplug_disable_before_freeze(void)
 545 {
 546         cpu_maps_update_begin();
 547         cpu_hotplug_disabled = 1;
 548         cpu_maps_update_done();
 549 }
 550
 551
 552 /*
 553  * When tasks have been thawed, re-enable regular CPU hotplug (which had been
 554  * disabled while beginning to freeze tasks).
 555  */
 556 void cpu_hotplug_enable_after_thaw(void)
 557 {
 558         cpu_maps_update_begin();
 559         cpu_hotplug_disabled = 0;
 560         cpu_maps_update_done();
 561 }
 562
 563 /*
 564  * When callbacks for CPU hotplug notifications are being executed, we must
 565  * ensure that the state of the system with respect to the tasks being frozen
 566  * or not, as reported by the notification, remains unchanged *throughout the
 567  * duration* of the execution of the callbacks.
 568  * Hence we need to prevent the freezer from racing with regular CPU hotplug.
 569  *
 570  * This synchronization is implemented by mutually excluding regular CPU
 571  * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
 572  * Hibernate notifications.
 573  */
 574 static int
 575 cpu_hotplug_pm_callback(struct notifier_block *nb,
 576                         unsigned long action, void *ptr)
 577 {
 578         switch (action) {
 579
 580         case PM_SUSPEND_PREPARE:
 581         case PM_HIBERNATION_PREPARE:
 582                 cpu_hotplug_disable_before_freeze();
 583                 break;
 584
 585         case PM_POST_SUSPEND:
 586         case PM_POST_HIBERNATION:
 587                 cpu_hotplug_enable_after_thaw();
 588                 break;
 589
 590         default:
 591                 return NOTIFY_DONE;
 592         }
 593
 594         return NOTIFY_OK;
 595 }
 596
 597
 598 static int __init cpu_hotplug_pm_sync_init(void)
 599 {
 600         pm_notifier(cpu_hotplug_pm_callback, 0);
 601         return 0;
 602 }
 603 core_initcall(cpu_hotplug_pm_sync_init);
 604
 605 #endif /* CONFIG_PM_SLEEP_SMP */
 606
 607 /**
 608  * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
 609  * @cpu: cpu that just started
 610  *
 611  * This function calls the cpu_chain notifiers with CPU_STARTING.
 612  * It must be called by the arch code on the new cpu, before the new cpu
 613  * enables interrupts and before the "boot" cpu returns from __cpu_up().
 614  */
 615 void __cpuinit notify_cpu_starting(unsigned int cpu)
 616 {
 617         unsigned long val = CPU_STARTING;
 618
 619 #ifdef CONFIG_PM_SLEEP_SMP
 620         if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
 621                 val = CPU_STARTING_FROZEN;
 622 #endif /* CONFIG_PM_SLEEP_SMP */
 623         cpu_notify(val, (void *)(long)cpu);
 624 }
 625
 626 #endif /* CONFIG_SMP */
 627
 628 /*
 629  * cpu_bit_bitmap[] is a special, "compressed" data structure that
 630  * represents all NR_CPUS bits binary values of 1<<nr.
 631  *
 632  * It is used by cpumask_of() to get a constant address to a CPU
 633  * mask value that has a single bit set only.
 634  */
 635
 636 /* cpu_bit_bitmap[0] is empty - so we can back into it */
 637 #define MASK_DECLARE_1(x)       [x+1][0] = (1UL << (x))
 638 #define MASK_DECLARE_2(x)       MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
 639 #define MASK_DECLARE_4(x)       MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
 640 #define MASK_DECLARE_8(x)       MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
 641
 642 const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
 643
 644         MASK_DECLARE_8(0),      MASK_DECLARE_8(8),
 645         MASK_DECLARE_8(16),     MASK_DECLARE_8(24),
 646 #if BITS_PER_LONG > 32
 647         MASK_DECLARE_8(32),     MASK_DECLARE_8(40),
 648         MASK_DECLARE_8(48),     MASK_DECLARE_8(56),
 649 #endif
 650 };
 651 EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
 652
 653 const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
 654 EXPORT_SYMBOL(cpu_all_bits);
 655
 656 #ifdef CONFIG_INIT_ALL_POSSIBLE
 657 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
 658         = CPU_BITS_ALL;
 659 #else
 660 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
 661 #endif
 662 const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
 663 EXPORT_SYMBOL(cpu_possible_mask);
 664
 665 static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
 666 const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
 667 EXPORT_SYMBOL(cpu_online_mask);
 668
 669 static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
 670 const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
 671 EXPORT_SYMBOL(cpu_present_mask);
 672
 673 static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
 674 const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
 675 EXPORT_SYMBOL(cpu_active_mask);
 676
 677 void set_cpu_possible(unsigned int cpu, bool possible)
 678 {
 679         if (possible)
 680                 cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
 681         else
 682                 cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
 683 }
 684
 685 void set_cpu_present(unsigned int cpu, bool present)
 686 {
 687         if (present)
 688                 cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
 689         else
 690                 cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
 691 }
 692
 693 void set_cpu_online(unsigned int cpu, bool online)
 694 {
 695         if (online)
 696                 cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
 697         else
 698                 cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
 699 }
 700
 701 void set_cpu_active(unsigned int cpu, bool active)
 702 {
 703         if (active)
 704                 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
 705         else
 706                 cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
 707 }
 708
 709 void init_cpu_present(const struct cpumask *src)
 710 {
 711         cpumask_copy(to_cpumask(cpu_present_bits), src);
 712 }
 713
 714 void init_cpu_possible(const struct cpumask *src)
 715 {
 716         cpumask_copy(to_cpumask(cpu_possible_bits), src);
 717 }
 718
 719 void init_cpu_online(const struct cpumask *src)
 720 {
 721         cpumask_copy(to_cpumask(cpu_online_bits), src);
 722 }