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