linux/kernel/cpu.c
<<
>>
Prefs
   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 */
  27static 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 */
  33void cpu_maps_update_begin(void)
  34{
  35        mutex_lock(&cpu_add_remove_lock);
  36}
  37
  38void cpu_maps_update_done(void)
  39{
  40        mutex_unlock(&cpu_add_remove_lock);
  41}
  42
  43static 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 */
  48static int cpu_hotplug_disabled;
  49
  50#ifdef CONFIG_HOTPLUG_CPU
  51
  52static 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
  66void 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}
  76EXPORT_SYMBOL_GPL(get_online_cpus);
  77
  78void 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}
  92EXPORT_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 */
 116static 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
 130static 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 */
 137static void cpu_hotplug_begin(void) {}
 138static void cpu_hotplug_done(void) {}
 139#endif  /* #else #if CONFIG_HOTPLUG_CPU */
 140
 141/* Need to know about CPUs going up/down? */
 142int __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
 151static 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
 162static 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
 169static void cpu_notify_nofail(unsigned long val, void *v)
 170{
 171        BUG_ON(cpu_notify(val, v));
 172}
 173EXPORT_SYMBOL(register_cpu_notifier);
 174
 175void __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}
 181EXPORT_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 */
 195void 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
 224static 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
 242struct take_cpu_down_param {
 243        unsigned long mod;
 244        void *hcpu;
 245};
 246
 247/* Take this CPU down. */
 248static 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 */
 265static 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
 320out_release:
 321        cpu_hotplug_done();
 322        if (!err)
 323                cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
 324        return err;
 325}
 326
 327int __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
 340out:
 341        cpu_maps_update_done();
 342        return err;
 343}
 344EXPORT_SYMBOL(cpu_down);
 345#endif /*CONFIG_HOTPLUG_CPU*/
 346
 347/* Requires cpu_add_remove_lock to be held */
 348static 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
 392out_notify:
 393        if (ret != 0)
 394                __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 395out:
 396        cpu_hotplug_done();
 397
 398        return ret;
 399}
 400
 401int __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
 451out:
 452        cpu_maps_update_done();
 453        return err;
 454}
 455EXPORT_SYMBOL_GPL(cpu_up);
 456
 457#ifdef CONFIG_PM_SLEEP_SMP
 458static cpumask_var_t frozen_cpus;
 459
 460int 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
 497void __weak arch_enable_nonboot_cpus_begin(void)
 498{
 499}
 500
 501void __weak arch_enable_nonboot_cpus_end(void)
 502{
 503}
 504
 505void __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);
 531out:
 532        cpu_maps_update_done();
 533}
 534
 535static 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}
 541core_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 */
 554void 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 */
 566void 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 */
 584static int
 585cpu_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
 608static 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}
 618core_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 */
 630void __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
 657const 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};
 666EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
 667
 668const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
 669EXPORT_SYMBOL(cpu_all_bits);
 670
 671#ifdef CONFIG_INIT_ALL_POSSIBLE
 672static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
 673        = CPU_BITS_ALL;
 674#else
 675static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
 676#endif
 677const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
 678EXPORT_SYMBOL(cpu_possible_mask);
 679
 680static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
 681const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
 682EXPORT_SYMBOL(cpu_online_mask);
 683
 684static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
 685const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
 686EXPORT_SYMBOL(cpu_present_mask);
 687
 688static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
 689const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
 690EXPORT_SYMBOL(cpu_active_mask);
 691
 692void 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
 700void 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
 708void 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
 716void 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
 724void init_cpu_present(const struct cpumask *src)
 725{
 726        cpumask_copy(to_cpumask(cpu_present_bits), src);
 727}
 728
 729void init_cpu_possible(const struct cpumask *src)
 730{
 731        cpumask_copy(to_cpumask(cpu_possible_bits), src);
 732}
 733
 734void init_cpu_online(const struct cpumask *src)
 735{
 736        cpumask_copy(to_cpumask(cpu_online_bits), src);
 737}
 738
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.