linux/kernel/cpu.c
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   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
 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
 240struct take_cpu_down_param {
 241        unsigned long mod;
 242        void *hcpu;
 243};
 244
 245/* Take this CPU down. */
 246static 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 */
 261static 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
 316out_release:
 317        cpu_hotplug_done();
 318        if (!err)
 319                cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
 320        return err;
 321}
 322
 323int __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
 336out:
 337        cpu_maps_update_done();
 338        return err;
 339}
 340EXPORT_SYMBOL(cpu_down);
 341#endif /*CONFIG_HOTPLUG_CPU*/
 342
 343/* Requires cpu_add_remove_lock to be held */
 344static 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
 388out_notify:
 389        if (ret != 0)
 390                __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 391out:
 392        cpu_hotplug_done();
 393
 394        return ret;
 395}
 396
 397int __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
 447out:
 448        cpu_maps_update_done();
 449        return err;
 450}
 451EXPORT_SYMBOL_GPL(cpu_up);
 452
 453#ifdef CONFIG_PM_SLEEP_SMP
 454static cpumask_var_t frozen_cpus;
 455
 456int 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
 493void __weak arch_enable_nonboot_cpus_begin(void)
 494{
 495}
 496
 497void __weak arch_enable_nonboot_cpus_end(void)
 498{
 499}
 500
 501void __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);
 527out:
 528        cpu_maps_update_done();
 529}
 530
 531static 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}
 537core_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 */
 550void 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 */
 562void 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 */
 580static int
 581cpu_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
 604static 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}
 614core_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 */
 626void __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
 653const 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};
 662EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
 663
 664const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
 665EXPORT_SYMBOL(cpu_all_bits);
 666
 667#ifdef CONFIG_INIT_ALL_POSSIBLE
 668static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
 669        = CPU_BITS_ALL;
 670#else
 671static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
 672#endif
 673const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
 674EXPORT_SYMBOL(cpu_possible_mask);
 675
 676static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
 677const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
 678EXPORT_SYMBOL(cpu_online_mask);
 679
 680static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
 681const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
 682EXPORT_SYMBOL(cpu_present_mask);
 683
 684static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
 685const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
 686EXPORT_SYMBOL(cpu_active_mask);
 687
 688void 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
 696void 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
 704void 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
 712void 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
 720void init_cpu_present(const struct cpumask *src)
 721{
 722        cpumask_copy(to_cpumask(cpu_present_bits), src);
 723}
 724
 725void init_cpu_possible(const struct cpumask *src)
 726{
 727        cpumask_copy(to_cpumask(cpu_possible_bits), src);
 728}
 729
 730void init_cpu_online(const struct cpumask *src)
 731{
 732        cpumask_copy(to_cpumask(cpu_online_bits), src);
 733}
 734
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