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/export.h>
  14 #include <linux/kthread.h>
  15 #include <linux/stop_machine.h>
  16 #include <linux/mutex.h>
  17 #include <linux/gfp.h>
  18 #include <linux/suspend.h>
  19
  20 #include "smpboot.h"
  21
  22 #ifdef CONFIG_SMP
  23 /* Serializes the updates to cpu_online_mask, cpu_present_mask */
  24 static DEFINE_MUTEX(cpu_add_remove_lock);
  25
  26 /*
  27  * The following two API's must be used when attempting
  28  * to serialize the updates to cpu_online_mask, cpu_present_mask.
  29  */
  30 void cpu_maps_update_begin(void)
  31 {
  32         mutex_lock(&cpu_add_remove_lock);
  33 }
  34
  35 void cpu_maps_update_done(void)
  36 {
  37         mutex_unlock(&cpu_add_remove_lock);
  38 }
  39
  40 static RAW_NOTIFIER_HEAD(cpu_chain);
  41
  42 /* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
  43  * Should always be manipulated under cpu_add_remove_lock
  44  */
  45 static int cpu_hotplug_disabled;
  46
  47 #ifdef CONFIG_HOTPLUG_CPU
  48
  49 static struct {
  50         struct task_struct *active_writer;
  51         struct mutex lock; /* Synchronizes accesses to refcount, */
  52         /*
  53          * Also blocks the new readers during
  54          * an ongoing cpu hotplug operation.
  55          */
  56         int refcount;
  57 } cpu_hotplug = {
  58         .active_writer = NULL,
  59         .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
  60         .refcount = 0,
  61 };
  62
  63 void get_online_cpus(void)
  64 {
  65         might_sleep();
  66         if (cpu_hotplug.active_writer == current)
  67                 return;
  68         mutex_lock(&cpu_hotplug.lock);
  69         cpu_hotplug.refcount++;
  70         mutex_unlock(&cpu_hotplug.lock);
  71
  72 }
  73 EXPORT_SYMBOL_GPL(get_online_cpus);
  74
  75 void put_online_cpus(void)
  76 {
  77         if (cpu_hotplug.active_writer == current)
  78                 return;
  79         mutex_lock(&cpu_hotplug.lock);
  80         if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
  81                 wake_up_process(cpu_hotplug.active_writer);
  82         mutex_unlock(&cpu_hotplug.lock);
  83
  84 }
  85 EXPORT_SYMBOL_GPL(put_online_cpus);
  86
  87 /*
  88  * This ensures that the hotplug operation can begin only when the
  89  * refcount goes to zero.
  90  *
  91  * Note that during a cpu-hotplug operation, the new readers, if any,
  92  * will be blocked by the cpu_hotplug.lock
  93  *
  94  * Since cpu_hotplug_begin() is always called after invoking
  95  * cpu_maps_update_begin(), we can be sure that only one writer is active.
  96  *
  97  * Note that theoretically, there is a possibility of a livelock:
  98  * - Refcount goes to zero, last reader wakes up the sleeping
  99  *   writer.
 100  * - Last reader unlocks the cpu_hotplug.lock.
 101  * - A new reader arrives at this moment, bumps up the refcount.
 102  * - The writer acquires the cpu_hotplug.lock finds the refcount
 103  *   non zero and goes to sleep again.
 104  *
 105  * However, this is very difficult to achieve in practice since
 106  * get_online_cpus() not an api which is called all that often.
 107  *
 108  */
 109 static void cpu_hotplug_begin(void)
 110 {
 111         cpu_hotplug.active_writer = current;
 112
 113         for (;;) {
 114                 mutex_lock(&cpu_hotplug.lock);
 115                 if (likely(!cpu_hotplug.refcount))
 116                         break;
 117                 __set_current_state(TASK_UNINTERRUPTIBLE);
 118                 mutex_unlock(&cpu_hotplug.lock);
 119                 schedule();
 120         }
 121 }
 122
 123 static void cpu_hotplug_done(void)
 124 {
 125         cpu_hotplug.active_writer = NULL;
 126         mutex_unlock(&cpu_hotplug.lock);
 127 }
 128
 129 #else /* #if CONFIG_HOTPLUG_CPU */
 130 static void cpu_hotplug_begin(void) {}
 131 static void cpu_hotplug_done(void) {}
 132 #endif  /* #else #if CONFIG_HOTPLUG_CPU */
 133
 134 /* Need to know about CPUs going up/down? */
 135 int __ref register_cpu_notifier(struct notifier_block *nb)
 136 {
 137         int ret;
 138         cpu_maps_update_begin();
 139         ret = raw_notifier_chain_register(&cpu_chain, nb);
 140         cpu_maps_update_done();
 141         return ret;
 142 }
 143
 144 static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
 145                         int *nr_calls)
 146 {
 147         int ret;
 148
 149         ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
 150                                         nr_calls);
 151
 152         return notifier_to_errno(ret);
 153 }
 154
 155 static int cpu_notify(unsigned long val, void *v)
 156 {
 157         return __cpu_notify(val, v, -1, NULL);
 158 }
 159
 160 #ifdef CONFIG_HOTPLUG_CPU
 161
 162 static void cpu_notify_nofail(unsigned long val, void *v)
 163 {
 164         BUG_ON(cpu_notify(val, v));
 165 }
 166 EXPORT_SYMBOL(register_cpu_notifier);
 167
 168 void __ref unregister_cpu_notifier(struct notifier_block *nb)
 169 {
 170         cpu_maps_update_begin();
 171         raw_notifier_chain_unregister(&cpu_chain, nb);
 172         cpu_maps_update_done();
 173 }
 174 EXPORT_SYMBOL(unregister_cpu_notifier);
 175
 176 static inline void check_for_tasks(int cpu)
 177 {
 178         struct task_struct *p;
 179
 180         write_lock_irq(&tasklist_lock);
 181         for_each_process(p) {
 182                 if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
 183                     (p->utime || p->stime))
 184                         printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "
 185                                 "(state = %ld, flags = %x)\n",
 186                                 p->comm, task_pid_nr(p), cpu,
 187                                 p->state, p->flags);
 188         }
 189         write_unlock_irq(&tasklist_lock);
 190 }
 191
 192 struct take_cpu_down_param {
 193         unsigned long mod;
 194         void *hcpu;
 195 };
 196
 197 /* Take this CPU down. */
 198 static int __ref take_cpu_down(void *_param)
 199 {
 200         struct take_cpu_down_param *param = _param;
 201         int err;
 202
 203         /* Ensure this CPU doesn't handle any more interrupts. */
 204         err = __cpu_disable();
 205         if (err < 0)
 206                 return err;
 207
 208         cpu_notify(CPU_DYING | param->mod, param->hcpu);
 209         return 0;
 210 }
 211
 212 /* Requires cpu_add_remove_lock to be held */
 213 static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
 214 {
 215         int err, nr_calls = 0;
 216         void *hcpu = (void *)(long)cpu;
 217         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
 218         struct take_cpu_down_param tcd_param = {
 219                 .mod = mod,
 220                 .hcpu = hcpu,
 221         };
 222
 223         if (num_online_cpus() == 1)
 224                 return -EBUSY;
 225
 226         if (!cpu_online(cpu))
 227                 return -EINVAL;
 228
 229         cpu_hotplug_begin();
 230
 231         err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
 232         if (err) {
 233                 nr_calls--;
 234                 __cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
 235                 printk("%s: attempt to take down CPU %u failed\n",
 236                                 __func__, cpu);
 237                 goto out_release;
 238         }
 239
 240         err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
 241         if (err) {
 242                 /* CPU didn't die: tell everyone.  Can't complain. */
 243                 cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
 244
 245                 goto out_release;
 246         }
 247         BUG_ON(cpu_online(cpu));
 248
 249         /*
 250          * The migration_call() CPU_DYING callback will have removed all
 251          * runnable tasks from the cpu, there's only the idle task left now
 252          * that the migration thread is done doing the stop_machine thing.
 253          *
 254          * Wait for the stop thread to go away.
 255          */
 256         while (!idle_cpu(cpu))
 257                 cpu_relax();
 258
 259         /* This actually kills the CPU. */
 260         __cpu_die(cpu);
 261
 262         /* CPU is completely dead: tell everyone.  Too late to complain. */
 263         cpu_notify_nofail(CPU_DEAD | mod, hcpu);
 264
 265         check_for_tasks(cpu);
 266
 267 out_release:
 268         cpu_hotplug_done();
 269         if (!err)
 270                 cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
 271         return err;
 272 }
 273
 274 int __ref cpu_down(unsigned int cpu)
 275 {
 276         int err;
 277
 278         cpu_maps_update_begin();
 279
 280         if (cpu_hotplug_disabled) {
 281                 err = -EBUSY;
 282                 goto out;
 283         }
 284
 285         err = _cpu_down(cpu, 0);
 286
 287 out:
 288         cpu_maps_update_done();
 289         return err;
 290 }
 291 EXPORT_SYMBOL(cpu_down);
 292 #endif /*CONFIG_HOTPLUG_CPU*/
 293
 294 /* Requires cpu_add_remove_lock to be held */
 295 static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
 296 {
 297         int ret, nr_calls = 0;
 298         void *hcpu = (void *)(long)cpu;
 299         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
 300         struct task_struct *idle;
 301
 302         if (cpu_online(cpu) || !cpu_present(cpu))
 303                 return -EINVAL;
 304
 305         cpu_hotplug_begin();
 306
 307         idle = idle_thread_get(cpu);
 308         if (IS_ERR(idle)) {
 309                 ret = PTR_ERR(idle);
 310                 goto out;
 311         }
 312
 313         ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
 314         if (ret) {
 315                 nr_calls--;
 316                 printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
 317                                 __func__, cpu);
 318                 goto out_notify;
 319         }
 320
 321         /* Arch-specific enabling code. */
 322         ret = __cpu_up(cpu, idle);
 323         if (ret != 0)
 324                 goto out_notify;
 325         BUG_ON(!cpu_online(cpu));
 326
 327         /* Now call notifier in preparation. */
 328         cpu_notify(CPU_ONLINE | mod, hcpu);
 329
 330 out_notify:
 331         if (ret != 0)
 332                 __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 333 out:
 334         cpu_hotplug_done();
 335
 336         return ret;
 337 }
 338
 339 int __cpuinit cpu_up(unsigned int cpu)
 340 {
 341         int err = 0;
 342
 343 #ifdef  CONFIG_MEMORY_HOTPLUG
 344         int nid;
 345         pg_data_t       *pgdat;
 346 #endif
 347
 348         if (!cpu_possible(cpu)) {
 349                 printk(KERN_ERR "can't online cpu %d because it is not "
 350                         "configured as may-hotadd at boot time\n", cpu);
 351 #if defined(CONFIG_IA64)
 352                 printk(KERN_ERR "please check additional_cpus= boot "
 353                                 "parameter\n");
 354 #endif
 355                 return -EINVAL;
 356         }
 357
 358 #ifdef  CONFIG_MEMORY_HOTPLUG
 359         nid = cpu_to_node(cpu);
 360         if (!node_online(nid)) {
 361                 err = mem_online_node(nid);
 362                 if (err)
 363                         return err;
 364         }
 365
 366         pgdat = NODE_DATA(nid);
 367         if (!pgdat) {
 368                 printk(KERN_ERR
 369                         "Can't online cpu %d due to NULL pgdat\n", cpu);
 370                 return -ENOMEM;
 371         }
 372
 373         if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
 374                 mutex_lock(&zonelists_mutex);
 375                 build_all_zonelists(NULL);
 376                 mutex_unlock(&zonelists_mutex);
 377         }
 378 #endif
 379
 380         cpu_maps_update_begin();
 381
 382         if (cpu_hotplug_disabled) {
 383                 err = -EBUSY;
 384                 goto out;
 385         }
 386
 387         err = _cpu_up(cpu, 0);
 388
 389 out:
 390         cpu_maps_update_done();
 391         return err;
 392 }
 393 EXPORT_SYMBOL_GPL(cpu_up);
 394
 395 #ifdef CONFIG_PM_SLEEP_SMP
 396 static cpumask_var_t frozen_cpus;
 397
 398 void __weak arch_disable_nonboot_cpus_begin(void)
 399 {
 400 }
 401
 402 void __weak arch_disable_nonboot_cpus_end(void)
 403 {
 404 }
 405
 406 int disable_nonboot_cpus(void)
 407 {
 408         int cpu, first_cpu, error = 0;
 409
 410         cpu_maps_update_begin();
 411         first_cpu = cpumask_first(cpu_online_mask);
 412         /*
 413          * We take down all of the non-boot CPUs in one shot to avoid races
 414          * with the userspace trying to use the CPU hotplug at the same time
 415          */
 416         cpumask_clear(frozen_cpus);
 417         arch_disable_nonboot_cpus_begin();
 418
 419         printk("Disabling non-boot CPUs ...\n");
 420         for_each_online_cpu(cpu) {
 421                 if (cpu == first_cpu)
 422                         continue;
 423                 error = _cpu_down(cpu, 1);
 424                 if (!error)
 425                         cpumask_set_cpu(cpu, frozen_cpus);
 426                 else {
 427                         printk(KERN_ERR "Error taking CPU%d down: %d\n",
 428                                 cpu, error);
 429                         break;
 430                 }
 431         }
 432
 433         arch_disable_nonboot_cpus_end();
 434
 435         if (!error) {
 436                 BUG_ON(num_online_cpus() > 1);
 437                 /* Make sure the CPUs won't be enabled by someone else */
 438                 cpu_hotplug_disabled = 1;
 439         } else {
 440                 printk(KERN_ERR "Non-boot CPUs are not disabled\n");
 441         }
 442         cpu_maps_update_done();
 443         return error;
 444 }
 445
 446 void __weak arch_enable_nonboot_cpus_begin(void)
 447 {
 448 }
 449
 450 void __weak arch_enable_nonboot_cpus_end(void)
 451 {
 452 }
 453
 454 void __ref enable_nonboot_cpus(void)
 455 {
 456         int cpu, error;
 457
 458         /* Allow everyone to use the CPU hotplug again */
 459         cpu_maps_update_begin();
 460         cpu_hotplug_disabled = 0;
 461         if (cpumask_empty(frozen_cpus))
 462                 goto out;
 463
 464         printk(KERN_INFO "Enabling non-boot CPUs ...\n");
 465
 466         arch_enable_nonboot_cpus_begin();
 467
 468         for_each_cpu(cpu, frozen_cpus) {
 469                 error = _cpu_up(cpu, 1);
 470                 if (!error) {
 471                         printk(KERN_INFO "CPU%d is up\n", cpu);
 472                         continue;
 473                 }
 474                 printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
 475         }
 476
 477         arch_enable_nonboot_cpus_end();
 478
 479         cpumask_clear(frozen_cpus);
 480 out:
 481         cpu_maps_update_done();
 482 }
 483
 484 static int __init alloc_frozen_cpus(void)
 485 {
 486         if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
 487                 return -ENOMEM;
 488         return 0;
 489 }
 490 core_initcall(alloc_frozen_cpus);
 491
 492 /*
 493  * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
 494  * hotplug when tasks are about to be frozen. Also, don't allow the freezer
 495  * to continue until any currently running CPU hotplug operation gets
 496  * completed.
 497  * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
 498  * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
 499  * CPU hotplug path and released only after it is complete. Thus, we
 500  * (and hence the freezer) will block here until any currently running CPU
 501  * hotplug operation gets completed.
 502  */
 503 void cpu_hotplug_disable_before_freeze(void)
 504 {
 505         cpu_maps_update_begin();
 506         cpu_hotplug_disabled = 1;
 507         cpu_maps_update_done();
 508 }
 509
 510
 511 /*
 512  * When tasks have been thawed, re-enable regular CPU hotplug (which had been
 513  * disabled while beginning to freeze tasks).
 514  */
 515 void cpu_hotplug_enable_after_thaw(void)
 516 {
 517         cpu_maps_update_begin();
 518         cpu_hotplug_disabled = 0;
 519         cpu_maps_update_done();
 520 }
 521
 522 /*
 523  * When callbacks for CPU hotplug notifications are being executed, we must
 524  * ensure that the state of the system with respect to the tasks being frozen
 525  * or not, as reported by the notification, remains unchanged *throughout the
 526  * duration* of the execution of the callbacks.
 527  * Hence we need to prevent the freezer from racing with regular CPU hotplug.
 528  *
 529  * This synchronization is implemented by mutually excluding regular CPU
 530  * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
 531  * Hibernate notifications.
 532  */
 533 static int
 534 cpu_hotplug_pm_callback(struct notifier_block *nb,
 535                         unsigned long action, void *ptr)
 536 {
 537         switch (action) {
 538
 539         case PM_SUSPEND_PREPARE:
 540         case PM_HIBERNATION_PREPARE:
 541                 cpu_hotplug_disable_before_freeze();
 542                 break;
 543
 544         case PM_POST_SUSPEND:
 545         case PM_POST_HIBERNATION:
 546                 cpu_hotplug_enable_after_thaw();
 547                 break;
 548
 549         default:
 550                 return NOTIFY_DONE;
 551         }
 552
 553         return NOTIFY_OK;
 554 }
 555
 556
 557 static int __init cpu_hotplug_pm_sync_init(void)
 558 {
 559         pm_notifier(cpu_hotplug_pm_callback, 0);
 560         return 0;
 561 }
 562 core_initcall(cpu_hotplug_pm_sync_init);
 563
 564 #endif /* CONFIG_PM_SLEEP_SMP */
 565
 566 /**
 567  * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
 568  * @cpu: cpu that just started
 569  *
 570  * This function calls the cpu_chain notifiers with CPU_STARTING.
 571  * It must be called by the arch code on the new cpu, before the new cpu
 572  * enables interrupts and before the "boot" cpu returns from __cpu_up().
 573  */
 574 void __cpuinit notify_cpu_starting(unsigned int cpu)
 575 {
 576         unsigned long val = CPU_STARTING;
 577
 578 #ifdef CONFIG_PM_SLEEP_SMP
 579         if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
 580                 val = CPU_STARTING_FROZEN;
 581 #endif /* CONFIG_PM_SLEEP_SMP */
 582         cpu_notify(val, (void *)(long)cpu);
 583 }
 584
 585 #endif /* CONFIG_SMP */
 586
 587 /*
 588  * cpu_bit_bitmap[] is a special, "compressed" data structure that
 589  * represents all NR_CPUS bits binary values of 1<<nr.
 590  *
 591  * It is used by cpumask_of() to get a constant address to a CPU
 592  * mask value that has a single bit set only.
 593  */
 594
 595 /* cpu_bit_bitmap[0] is empty - so we can back into it */
 596 #define MASK_DECLARE_1(x)       [x+1][0] = (1UL << (x))
 597 #define MASK_DECLARE_2(x)       MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
 598 #define MASK_DECLARE_4(x)       MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
 599 #define MASK_DECLARE_8(x)       MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
 600
 601 const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
 602
 603         MASK_DECLARE_8(0),      MASK_DECLARE_8(8),
 604         MASK_DECLARE_8(16),     MASK_DECLARE_8(24),
 605 #if BITS_PER_LONG > 32
 606         MASK_DECLARE_8(32),     MASK_DECLARE_8(40),
 607         MASK_DECLARE_8(48),     MASK_DECLARE_8(56),
 608 #endif
 609 };
 610 EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
 611
 612 const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
 613 EXPORT_SYMBOL(cpu_all_bits);
 614
 615 #ifdef CONFIG_INIT_ALL_POSSIBLE
 616 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
 617         = CPU_BITS_ALL;
 618 #else
 619 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
 620 #endif
 621 const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
 622 EXPORT_SYMBOL(cpu_possible_mask);
 623
 624 static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
 625 const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
 626 EXPORT_SYMBOL(cpu_online_mask);
 627
 628 static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
 629 const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
 630 EXPORT_SYMBOL(cpu_present_mask);
 631
 632 static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
 633 const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
 634 EXPORT_SYMBOL(cpu_active_mask);
 635
 636 void set_cpu_possible(unsigned int cpu, bool possible)
 637 {
 638         if (possible)
 639                 cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
 640         else
 641                 cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
 642 }
 643
 644 void set_cpu_present(unsigned int cpu, bool present)
 645 {
 646         if (present)
 647                 cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
 648         else
 649                 cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
 650 }
 651
 652 void set_cpu_online(unsigned int cpu, bool online)
 653 {
 654         if (online)
 655                 cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
 656         else
 657                 cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
 658 }
 659
 660 void set_cpu_active(unsigned int cpu, bool active)
 661 {
 662         if (active)
 663                 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
 664         else
 665                 cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
 666 }
 667
 668 void init_cpu_present(const struct cpumask *src)
 669 {
 670         cpumask_copy(to_cpumask(cpu_present_bits), src);
 671 }
 672
 673 void init_cpu_possible(const struct cpumask *src)
 674 {
 675         cpumask_copy(to_cpumask(cpu_possible_bits), src);
 676 }
 677
 678 void init_cpu_online(const struct cpumask *src)
 679 {
 680         cpumask_copy(to_cpumask(cpu_online_bits), src);
 681 }