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
 228         write_lock_irq(&tasklist_lock);
 229         for_each_process(p) {
 230                 if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
 231                     (p->utime || p->stime))
 232                         printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "
 233                                 "(state = %ld, flags = %x)\n",
 234                                 p->comm, task_pid_nr(p), cpu,
 235                                 p->state, p->flags);
 236         }
 237         write_unlock_irq(&tasklist_lock);
 238 }
 239
 240 struct take_cpu_down_param {
 241         unsigned long mod;
 242         void *hcpu;
 243 };
 244
 245 /* Take this CPU down. */
 246 static int __ref take_cpu_down(void *_param)
 247 {
 248         struct take_cpu_down_param *param = _param;
 249         int err;
 250
 251         /* Ensure this CPU doesn't handle any more interrupts. */
 252         err = __cpu_disable();
 253         if (err < 0)
 254                 return err;
 255
 256         cpu_notify(CPU_DYING | param->mod, param->hcpu);
 257         return 0;
 258 }
 259
 260 /* Requires cpu_add_remove_lock to be held */
 261 static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
 262 {
 263         int err, nr_calls = 0;
 264         void *hcpu = (void *)(long)cpu;
 265         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
 266         struct take_cpu_down_param tcd_param = {
 267                 .mod = mod,
 268                 .hcpu = hcpu,
 269         };
 270
 271         if (num_online_cpus() == 1)
 272                 return -EBUSY;
 273
 274         if (!cpu_online(cpu))
 275                 return -EINVAL;
 276
 277         cpu_hotplug_begin();
 278
 279         err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
 280         if (err) {
 281                 nr_calls--;
 282                 __cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
 283                 printk("%s: attempt to take down CPU %u failed\n",
 284                                 __func__, cpu);
 285                 goto out_release;
 286         }
 287         smpboot_park_threads(cpu);
 288
 289         err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
 290         if (err) {
 291                 /* CPU didn't die: tell everyone.  Can't complain. */
 292                 smpboot_unpark_threads(cpu);
 293                 cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
 294                 goto out_release;
 295         }
 296         BUG_ON(cpu_online(cpu));
 297
 298         /*
 299          * The migration_call() CPU_DYING callback will have removed all
 300          * runnable tasks from the cpu, there's only the idle task left now
 301          * that the migration thread is done doing the stop_machine thing.
 302          *
 303          * Wait for the stop thread to go away.
 304          */
 305         while (!idle_cpu(cpu))
 306                 cpu_relax();
 307
 308         /* This actually kills the CPU. */
 309         __cpu_die(cpu);
 310
 311         /* CPU is completely dead: tell everyone.  Too late to complain. */
 312         cpu_notify_nofail(CPU_DEAD | mod, hcpu);
 313
 314         check_for_tasks(cpu);
 315
 316 out_release:
 317         cpu_hotplug_done();
 318         if (!err)
 319                 cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
 320         return err;
 321 }
 322
 323 int __ref cpu_down(unsigned int cpu)
 324 {
 325         int err;
 326
 327         cpu_maps_update_begin();
 328
 329         if (cpu_hotplug_disabled) {
 330                 err = -EBUSY;
 331                 goto out;
 332         }
 333
 334         err = _cpu_down(cpu, 0);
 335
 336 out:
 337         cpu_maps_update_done();
 338         return err;
 339 }
 340 EXPORT_SYMBOL(cpu_down);
 341 #endif /*CONFIG_HOTPLUG_CPU*/
 342
 343 /* Requires cpu_add_remove_lock to be held */
 344 static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
 345 {
 346         int ret, nr_calls = 0;
 347         void *hcpu = (void *)(long)cpu;
 348         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
 349         struct task_struct *idle;
 350
 351         cpu_hotplug_begin();
 352
 353         if (cpu_online(cpu) || !cpu_present(cpu)) {
 354                 ret = -EINVAL;
 355                 goto out;
 356         }
 357
 358         idle = idle_thread_get(cpu);
 359         if (IS_ERR(idle)) {
 360                 ret = PTR_ERR(idle);
 361                 goto out;
 362         }
 363
 364         ret = smpboot_create_threads(cpu);
 365         if (ret)
 366                 goto out;
 367
 368         ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
 369         if (ret) {
 370                 nr_calls--;
 371                 printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
 372                                 __func__, cpu);
 373                 goto out_notify;
 374         }
 375
 376         /* Arch-specific enabling code. */
 377         ret = __cpu_up(cpu, idle);
 378         if (ret != 0)
 379                 goto out_notify;
 380         BUG_ON(!cpu_online(cpu));
 381
 382         /* Wake the per cpu threads */
 383         smpboot_unpark_threads(cpu);
 384
 385         /* Now call notifier in preparation. */
 386         cpu_notify(CPU_ONLINE | mod, hcpu);
 387
 388 out_notify:
 389         if (ret != 0)
 390                 __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 391 out:
 392         cpu_hotplug_done();
 393
 394         return ret;
 395 }
 396
 397 int __cpuinit cpu_up(unsigned int cpu)
 398 {
 399         int err = 0;
 400
 401 #ifdef  CONFIG_MEMORY_HOTPLUG
 402         int nid;
 403         pg_data_t       *pgdat;
 404 #endif
 405
 406         if (!cpu_possible(cpu)) {
 407                 printk(KERN_ERR "can't online cpu %d because it is not "
 408                         "configured as may-hotadd at boot time\n", cpu);
 409 #if defined(CONFIG_IA64)
 410                 printk(KERN_ERR "please check additional_cpus= boot "
 411                                 "parameter\n");
 412 #endif
 413                 return -EINVAL;
 414         }
 415
 416 #ifdef  CONFIG_MEMORY_HOTPLUG
 417         nid = cpu_to_node(cpu);
 418         if (!node_online(nid)) {
 419                 err = mem_online_node(nid);
 420                 if (err)
 421                         return err;
 422         }
 423
 424         pgdat = NODE_DATA(nid);
 425         if (!pgdat) {
 426                 printk(KERN_ERR
 427                         "Can't online cpu %d due to NULL pgdat\n", cpu);
 428                 return -ENOMEM;
 429         }
 430
 431         if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
 432                 mutex_lock(&zonelists_mutex);
 433                 build_all_zonelists(NULL, NULL);
 434                 mutex_unlock(&zonelists_mutex);
 435         }
 436 #endif
 437
 438         cpu_maps_update_begin();
 439
 440         if (cpu_hotplug_disabled) {
 441                 err = -EBUSY;
 442                 goto out;
 443         }
 444
 445         err = _cpu_up(cpu, 0);
 446
 447 out:
 448         cpu_maps_update_done();
 449         return err;
 450 }
 451 EXPORT_SYMBOL_GPL(cpu_up);
 452
 453 #ifdef CONFIG_PM_SLEEP_SMP
 454 static cpumask_var_t frozen_cpus;
 455
 456 int disable_nonboot_cpus(void)
 457 {
 458         int cpu, first_cpu, error = 0;
 459
 460         cpu_maps_update_begin();
 461         first_cpu = cpumask_first(cpu_online_mask);
 462         /*
 463          * We take down all of the non-boot CPUs in one shot to avoid races
 464          * with the userspace trying to use the CPU hotplug at the same time
 465          */
 466         cpumask_clear(frozen_cpus);
 467
 468         printk("Disabling non-boot CPUs ...\n");
 469         for_each_online_cpu(cpu) {
 470                 if (cpu == first_cpu)
 471                         continue;
 472                 error = _cpu_down(cpu, 1);
 473                 if (!error)
 474                         cpumask_set_cpu(cpu, frozen_cpus);
 475                 else {
 476                         printk(KERN_ERR "Error taking CPU%d down: %d\n",
 477                                 cpu, error);
 478                         break;
 479                 }
 480         }
 481
 482         if (!error) {
 483                 BUG_ON(num_online_cpus() > 1);
 484                 /* Make sure the CPUs won't be enabled by someone else */
 485                 cpu_hotplug_disabled = 1;
 486         } else {
 487                 printk(KERN_ERR "Non-boot CPUs are not disabled\n");
 488         }
 489         cpu_maps_update_done();
 490         return error;
 491 }
 492
 493 void __weak arch_enable_nonboot_cpus_begin(void)
 494 {
 495 }
 496
 497 void __weak arch_enable_nonboot_cpus_end(void)
 498 {
 499 }
 500
 501 void __ref enable_nonboot_cpus(void)
 502 {
 503         int cpu, error;
 504
 505         /* Allow everyone to use the CPU hotplug again */
 506         cpu_maps_update_begin();
 507         cpu_hotplug_disabled = 0;
 508         if (cpumask_empty(frozen_cpus))
 509                 goto out;
 510
 511         printk(KERN_INFO "Enabling non-boot CPUs ...\n");
 512
 513         arch_enable_nonboot_cpus_begin();
 514
 515         for_each_cpu(cpu, frozen_cpus) {
 516                 error = _cpu_up(cpu, 1);
 517                 if (!error) {
 518                         printk(KERN_INFO "CPU%d is up\n", cpu);
 519                         continue;
 520                 }
 521                 printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
 522         }
 523
 524         arch_enable_nonboot_cpus_end();
 525
 526         cpumask_clear(frozen_cpus);
 527 out:
 528         cpu_maps_update_done();
 529 }
 530
 531 static int __init alloc_frozen_cpus(void)
 532 {
 533         if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
 534                 return -ENOMEM;
 535         return 0;
 536 }
 537 core_initcall(alloc_frozen_cpus);
 538
 539 /*
 540  * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
 541  * hotplug when tasks are about to be frozen. Also, don't allow the freezer
 542  * to continue until any currently running CPU hotplug operation gets
 543  * completed.
 544  * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
 545  * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
 546  * CPU hotplug path and released only after it is complete. Thus, we
 547  * (and hence the freezer) will block here until any currently running CPU
 548  * hotplug operation gets completed.
 549  */
 550 void cpu_hotplug_disable_before_freeze(void)
 551 {
 552         cpu_maps_update_begin();
 553         cpu_hotplug_disabled = 1;
 554         cpu_maps_update_done();
 555 }
 556
 557
 558 /*
 559  * When tasks have been thawed, re-enable regular CPU hotplug (which had been
 560  * disabled while beginning to freeze tasks).
 561  */
 562 void cpu_hotplug_enable_after_thaw(void)
 563 {
 564         cpu_maps_update_begin();
 565         cpu_hotplug_disabled = 0;
 566         cpu_maps_update_done();
 567 }
 568
 569 /*
 570  * When callbacks for CPU hotplug notifications are being executed, we must
 571  * ensure that the state of the system with respect to the tasks being frozen
 572  * or not, as reported by the notification, remains unchanged *throughout the
 573  * duration* of the execution of the callbacks.
 574  * Hence we need to prevent the freezer from racing with regular CPU hotplug.
 575  *
 576  * This synchronization is implemented by mutually excluding regular CPU
 577  * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
 578  * Hibernate notifications.
 579  */
 580 static int
 581 cpu_hotplug_pm_callback(struct notifier_block *nb,
 582                         unsigned long action, void *ptr)
 583 {
 584         switch (action) {
 585
 586         case PM_SUSPEND_PREPARE:
 587         case PM_HIBERNATION_PREPARE:
 588                 cpu_hotplug_disable_before_freeze();
 589                 break;
 590
 591         case PM_POST_SUSPEND:
 592         case PM_POST_HIBERNATION:
 593                 cpu_hotplug_enable_after_thaw();
 594                 break;
 595
 596         default:
 597                 return NOTIFY_DONE;
 598         }
 599
 600         return NOTIFY_OK;
 601 }
 602
 603
 604 static int __init cpu_hotplug_pm_sync_init(void)
 605 {
 606         /*
 607          * cpu_hotplug_pm_callback has higher priority than x86
 608          * bsp_pm_callback which depends on cpu_hotplug_pm_callback
 609          * to disable cpu hotplug to avoid cpu hotplug race.
 610          */
 611         pm_notifier(cpu_hotplug_pm_callback, 0);
 612         return 0;
 613 }
 614 core_initcall(cpu_hotplug_pm_sync_init);
 615
 616 #endif /* CONFIG_PM_SLEEP_SMP */
 617
 618 /**
 619  * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
 620  * @cpu: cpu that just started
 621  *
 622  * This function calls the cpu_chain notifiers with CPU_STARTING.
 623  * It must be called by the arch code on the new cpu, before the new cpu
 624  * enables interrupts and before the "boot" cpu returns from __cpu_up().
 625  */
 626 void __cpuinit notify_cpu_starting(unsigned int cpu)
 627 {
 628         unsigned long val = CPU_STARTING;
 629
 630 #ifdef CONFIG_PM_SLEEP_SMP
 631         if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
 632                 val = CPU_STARTING_FROZEN;
 633 #endif /* CONFIG_PM_SLEEP_SMP */
 634         cpu_notify(val, (void *)(long)cpu);
 635 }
 636
 637 #endif /* CONFIG_SMP */
 638
 639 /*
 640  * cpu_bit_bitmap[] is a special, "compressed" data structure that
 641  * represents all NR_CPUS bits binary values of 1<<nr.
 642  *
 643  * It is used by cpumask_of() to get a constant address to a CPU
 644  * mask value that has a single bit set only.
 645  */
 646
 647 /* cpu_bit_bitmap[0] is empty - so we can back into it */
 648 #define MASK_DECLARE_1(x)       [x+1][0] = (1UL << (x))
 649 #define MASK_DECLARE_2(x)       MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
 650 #define MASK_DECLARE_4(x)       MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
 651 #define MASK_DECLARE_8(x)       MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
 652
 653 const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
 654
 655         MASK_DECLARE_8(0),      MASK_DECLARE_8(8),
 656         MASK_DECLARE_8(16),     MASK_DECLARE_8(24),
 657 #if BITS_PER_LONG > 32
 658         MASK_DECLARE_8(32),     MASK_DECLARE_8(40),
 659         MASK_DECLARE_8(48),     MASK_DECLARE_8(56),
 660 #endif
 661 };
 662 EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
 663
 664 const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
 665 EXPORT_SYMBOL(cpu_all_bits);
 666
 667 #ifdef CONFIG_INIT_ALL_POSSIBLE
 668 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
 669         = CPU_BITS_ALL;
 670 #else
 671 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
 672 #endif
 673 const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
 674 EXPORT_SYMBOL(cpu_possible_mask);
 675
 676 static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
 677 const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
 678 EXPORT_SYMBOL(cpu_online_mask);
 679
 680 static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
 681 const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
 682 EXPORT_SYMBOL(cpu_present_mask);
 683
 684 static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
 685 const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
 686 EXPORT_SYMBOL(cpu_active_mask);
 687
 688 void set_cpu_possible(unsigned int cpu, bool possible)
 689 {
 690         if (possible)
 691                 cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
 692         else
 693                 cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
 694 }
 695
 696 void set_cpu_present(unsigned int cpu, bool present)
 697 {
 698         if (present)
 699                 cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
 700         else
 701                 cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
 702 }
 703
 704 void set_cpu_online(unsigned int cpu, bool online)
 705 {
 706         if (online)
 707                 cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
 708         else
 709                 cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
 710 }
 711
 712 void set_cpu_active(unsigned int cpu, bool active)
 713 {
 714         if (active)
 715                 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
 716         else
 717                 cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
 718 }
 719
 720 void init_cpu_present(const struct cpumask *src)
 721 {
 722         cpumask_copy(to_cpumask(cpu_present_bits), src);
 723 }
 724
 725 void init_cpu_possible(const struct cpumask *src)
 726 {
 727         cpumask_copy(to_cpumask(cpu_possible_bits), src);
 728 }
 729
 730 void init_cpu_online(const struct cpumask *src)
 731 {
 732         cpumask_copy(to_cpumask(cpu_online_bits), src);
 733 }