Root/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#include <linux/lockdep.h>
23
24#include "smpboot.h"
25
26#ifdef CONFIG_SMP
27/* Serializes the updates to cpu_online_mask, cpu_present_mask */
28static DEFINE_MUTEX(cpu_add_remove_lock);
29
30/*
31 * The following two APIs (cpu_maps_update_begin/done) must be used when
32 * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
33 * The APIs cpu_notifier_register_begin/done() must be used to protect CPU
34 * hotplug callback (un)registration performed using __register_cpu_notifier()
35 * or __unregister_cpu_notifier().
36 */
37void cpu_maps_update_begin(void)
38{
39    mutex_lock(&cpu_add_remove_lock);
40}
41EXPORT_SYMBOL(cpu_notifier_register_begin);
42
43void cpu_maps_update_done(void)
44{
45    mutex_unlock(&cpu_add_remove_lock);
46}
47EXPORT_SYMBOL(cpu_notifier_register_done);
48
49static RAW_NOTIFIER_HEAD(cpu_chain);
50
51/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
52 * Should always be manipulated under cpu_add_remove_lock
53 */
54static int cpu_hotplug_disabled;
55
56#ifdef CONFIG_HOTPLUG_CPU
57
58static struct {
59    struct task_struct *active_writer;
60    struct mutex lock; /* Synchronizes accesses to refcount, */
61    /*
62     * Also blocks the new readers during
63     * an ongoing cpu hotplug operation.
64     */
65    int refcount;
66
67#ifdef CONFIG_DEBUG_LOCK_ALLOC
68    struct lockdep_map dep_map;
69#endif
70} cpu_hotplug = {
71    .active_writer = NULL,
72    .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
73    .refcount = 0,
74#ifdef CONFIG_DEBUG_LOCK_ALLOC
75    .dep_map = {.name = "cpu_hotplug.lock" },
76#endif
77};
78
79/* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
80#define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
81#define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map)
82#define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map)
83
84void get_online_cpus(void)
85{
86    might_sleep();
87    if (cpu_hotplug.active_writer == current)
88        return;
89    cpuhp_lock_acquire_read();
90    mutex_lock(&cpu_hotplug.lock);
91    cpu_hotplug.refcount++;
92    mutex_unlock(&cpu_hotplug.lock);
93
94}
95EXPORT_SYMBOL_GPL(get_online_cpus);
96
97void put_online_cpus(void)
98{
99    if (cpu_hotplug.active_writer == current)
100        return;
101    mutex_lock(&cpu_hotplug.lock);
102
103    if (WARN_ON(!cpu_hotplug.refcount))
104        cpu_hotplug.refcount++; /* try to fix things up */
105
106    if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
107        wake_up_process(cpu_hotplug.active_writer);
108    mutex_unlock(&cpu_hotplug.lock);
109    cpuhp_lock_release();
110
111}
112EXPORT_SYMBOL_GPL(put_online_cpus);
113
114/*
115 * This ensures that the hotplug operation can begin only when the
116 * refcount goes to zero.
117 *
118 * Note that during a cpu-hotplug operation, the new readers, if any,
119 * will be blocked by the cpu_hotplug.lock
120 *
121 * Since cpu_hotplug_begin() is always called after invoking
122 * cpu_maps_update_begin(), we can be sure that only one writer is active.
123 *
124 * Note that theoretically, there is a possibility of a livelock:
125 * - Refcount goes to zero, last reader wakes up the sleeping
126 * writer.
127 * - Last reader unlocks the cpu_hotplug.lock.
128 * - A new reader arrives at this moment, bumps up the refcount.
129 * - The writer acquires the cpu_hotplug.lock finds the refcount
130 * non zero and goes to sleep again.
131 *
132 * However, this is very difficult to achieve in practice since
133 * get_online_cpus() not an api which is called all that often.
134 *
135 */
136void cpu_hotplug_begin(void)
137{
138    cpu_hotplug.active_writer = current;
139
140    cpuhp_lock_acquire();
141    for (;;) {
142        mutex_lock(&cpu_hotplug.lock);
143        if (likely(!cpu_hotplug.refcount))
144            break;
145        __set_current_state(TASK_UNINTERRUPTIBLE);
146        mutex_unlock(&cpu_hotplug.lock);
147        schedule();
148    }
149}
150
151void cpu_hotplug_done(void)
152{
153    cpu_hotplug.active_writer = NULL;
154    mutex_unlock(&cpu_hotplug.lock);
155    cpuhp_lock_release();
156}
157
158/*
159 * Wait for currently running CPU hotplug operations to complete (if any) and
160 * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
161 * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
162 * hotplug path before performing hotplug operations. So acquiring that lock
163 * guarantees mutual exclusion from any currently running hotplug operations.
164 */
165void cpu_hotplug_disable(void)
166{
167    cpu_maps_update_begin();
168    cpu_hotplug_disabled = 1;
169    cpu_maps_update_done();
170}
171
172void cpu_hotplug_enable(void)
173{
174    cpu_maps_update_begin();
175    cpu_hotplug_disabled = 0;
176    cpu_maps_update_done();
177}
178
179#endif /* CONFIG_HOTPLUG_CPU */
180
181/* Need to know about CPUs going up/down? */
182int __ref register_cpu_notifier(struct notifier_block *nb)
183{
184    int ret;
185    cpu_maps_update_begin();
186    ret = raw_notifier_chain_register(&cpu_chain, nb);
187    cpu_maps_update_done();
188    return ret;
189}
190
191int __ref __register_cpu_notifier(struct notifier_block *nb)
192{
193    return raw_notifier_chain_register(&cpu_chain, nb);
194}
195
196static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
197            int *nr_calls)
198{
199    int ret;
200
201    ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
202                    nr_calls);
203
204    return notifier_to_errno(ret);
205}
206
207static int cpu_notify(unsigned long val, void *v)
208{
209    return __cpu_notify(val, v, -1, NULL);
210}
211
212#ifdef CONFIG_HOTPLUG_CPU
213
214static void cpu_notify_nofail(unsigned long val, void *v)
215{
216    BUG_ON(cpu_notify(val, v));
217}
218EXPORT_SYMBOL(register_cpu_notifier);
219EXPORT_SYMBOL(__register_cpu_notifier);
220
221void __ref unregister_cpu_notifier(struct notifier_block *nb)
222{
223    cpu_maps_update_begin();
224    raw_notifier_chain_unregister(&cpu_chain, nb);
225    cpu_maps_update_done();
226}
227EXPORT_SYMBOL(unregister_cpu_notifier);
228
229void __ref __unregister_cpu_notifier(struct notifier_block *nb)
230{
231    raw_notifier_chain_unregister(&cpu_chain, nb);
232}
233EXPORT_SYMBOL(__unregister_cpu_notifier);
234
235/**
236 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
237 * @cpu: a CPU id
238 *
239 * This function walks all processes, finds a valid mm struct for each one and
240 * then clears a corresponding bit in mm's cpumask. While this all sounds
241 * trivial, there are various non-obvious corner cases, which this function
242 * tries to solve in a safe manner.
243 *
244 * Also note that the function uses a somewhat relaxed locking scheme, so it may
245 * be called only for an already offlined CPU.
246 */
247void clear_tasks_mm_cpumask(int cpu)
248{
249    struct task_struct *p;
250
251    /*
252     * This function is called after the cpu is taken down and marked
253     * offline, so its not like new tasks will ever get this cpu set in
254     * their mm mask. -- Peter Zijlstra
255     * Thus, we may use rcu_read_lock() here, instead of grabbing
256     * full-fledged tasklist_lock.
257     */
258    WARN_ON(cpu_online(cpu));
259    rcu_read_lock();
260    for_each_process(p) {
261        struct task_struct *t;
262
263        /*
264         * Main thread might exit, but other threads may still have
265         * a valid mm. Find one.
266         */
267        t = find_lock_task_mm(p);
268        if (!t)
269            continue;
270        cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
271        task_unlock(t);
272    }
273    rcu_read_unlock();
274}
275
276static inline void check_for_tasks(int cpu)
277{
278    struct task_struct *p;
279    cputime_t utime, stime;
280
281    write_lock_irq(&tasklist_lock);
282    for_each_process(p) {
283        task_cputime(p, &utime, &stime);
284        if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
285            (utime || stime))
286            printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "
287                "(state = %ld, flags = %x)\n",
288                p->comm, task_pid_nr(p), cpu,
289                p->state, p->flags);
290    }
291    write_unlock_irq(&tasklist_lock);
292}
293
294struct take_cpu_down_param {
295    unsigned long mod;
296    void *hcpu;
297};
298
299/* Take this CPU down. */
300static int __ref take_cpu_down(void *_param)
301{
302    struct take_cpu_down_param *param = _param;
303    int err;
304
305    /* Ensure this CPU doesn't handle any more interrupts. */
306    err = __cpu_disable();
307    if (err < 0)
308        return err;
309
310    cpu_notify(CPU_DYING | param->mod, param->hcpu);
311    /* Park the stopper thread */
312    kthread_park(current);
313    return 0;
314}
315
316/* Requires cpu_add_remove_lock to be held */
317static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
318{
319    int err, nr_calls = 0;
320    void *hcpu = (void *)(long)cpu;
321    unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
322    struct take_cpu_down_param tcd_param = {
323        .mod = mod,
324        .hcpu = hcpu,
325    };
326
327    if (num_online_cpus() == 1)
328        return -EBUSY;
329
330    if (!cpu_online(cpu))
331        return -EINVAL;
332
333    cpu_hotplug_begin();
334
335    err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
336    if (err) {
337        nr_calls--;
338        __cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
339        printk("%s: attempt to take down CPU %u failed\n",
340                __func__, cpu);
341        goto out_release;
342    }
343
344    /*
345     * By now we've cleared cpu_active_mask, wait for all preempt-disabled
346     * and RCU users of this state to go away such that all new such users
347     * will observe it.
348     *
349     * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
350     * not imply sync_sched(), so explicitly call both.
351     *
352     * Do sync before park smpboot threads to take care the rcu boost case.
353     */
354#ifdef CONFIG_PREEMPT
355    synchronize_sched();
356#endif
357    synchronize_rcu();
358
359    smpboot_park_threads(cpu);
360
361    /*
362     * So now all preempt/rcu users must observe !cpu_active().
363     */
364
365    err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
366    if (err) {
367        /* CPU didn't die: tell everyone. Can't complain. */
368        smpboot_unpark_threads(cpu);
369        cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
370        goto out_release;
371    }
372    BUG_ON(cpu_online(cpu));
373
374    /*
375     * The migration_call() CPU_DYING callback will have removed all
376     * runnable tasks from the cpu, there's only the idle task left now
377     * that the migration thread is done doing the stop_machine thing.
378     *
379     * Wait for the stop thread to go away.
380     */
381    while (!idle_cpu(cpu))
382        cpu_relax();
383
384    /* This actually kills the CPU. */
385    __cpu_die(cpu);
386
387    /* CPU is completely dead: tell everyone. Too late to complain. */
388    cpu_notify_nofail(CPU_DEAD | mod, hcpu);
389
390    check_for_tasks(cpu);
391
392out_release:
393    cpu_hotplug_done();
394    if (!err)
395        cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
396    return err;
397}
398
399int __ref cpu_down(unsigned int cpu)
400{
401    int err;
402
403    cpu_maps_update_begin();
404
405    if (cpu_hotplug_disabled) {
406        err = -EBUSY;
407        goto out;
408    }
409
410    err = _cpu_down(cpu, 0);
411
412out:
413    cpu_maps_update_done();
414    return err;
415}
416EXPORT_SYMBOL(cpu_down);
417#endif /*CONFIG_HOTPLUG_CPU*/
418
419/* Requires cpu_add_remove_lock to be held */
420static int _cpu_up(unsigned int cpu, int tasks_frozen)
421{
422    int ret, nr_calls = 0;
423    void *hcpu = (void *)(long)cpu;
424    unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
425    struct task_struct *idle;
426
427    cpu_hotplug_begin();
428
429    if (cpu_online(cpu) || !cpu_present(cpu)) {
430        ret = -EINVAL;
431        goto out;
432    }
433
434    idle = idle_thread_get(cpu);
435    if (IS_ERR(idle)) {
436        ret = PTR_ERR(idle);
437        goto out;
438    }
439
440    ret = smpboot_create_threads(cpu);
441    if (ret)
442        goto out;
443
444    ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
445    if (ret) {
446        nr_calls--;
447        printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
448                __func__, cpu);
449        goto out_notify;
450    }
451
452    /* Arch-specific enabling code. */
453    ret = __cpu_up(cpu, idle);
454    if (ret != 0)
455        goto out_notify;
456    BUG_ON(!cpu_online(cpu));
457
458    /* Wake the per cpu threads */
459    smpboot_unpark_threads(cpu);
460
461    /* Now call notifier in preparation. */
462    cpu_notify(CPU_ONLINE | mod, hcpu);
463
464out_notify:
465    if (ret != 0)
466        __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
467out:
468    cpu_hotplug_done();
469
470    return ret;
471}
472
473int cpu_up(unsigned int cpu)
474{
475    int err = 0;
476
477    if (!cpu_possible(cpu)) {
478        printk(KERN_ERR "can't online cpu %d because it is not "
479            "configured as may-hotadd at boot time\n", cpu);
480#if defined(CONFIG_IA64)
481        printk(KERN_ERR "please check additional_cpus= boot "
482                "parameter\n");
483#endif
484        return -EINVAL;
485    }
486
487    err = try_online_node(cpu_to_node(cpu));
488    if (err)
489        return err;
490
491    cpu_maps_update_begin();
492
493    if (cpu_hotplug_disabled) {
494        err = -EBUSY;
495        goto out;
496    }
497
498    err = _cpu_up(cpu, 0);
499
500out:
501    cpu_maps_update_done();
502    return err;
503}
504EXPORT_SYMBOL_GPL(cpu_up);
505
506#ifdef CONFIG_PM_SLEEP_SMP
507static cpumask_var_t frozen_cpus;
508
509int disable_nonboot_cpus(void)
510{
511    int cpu, first_cpu, error = 0;
512
513    cpu_maps_update_begin();
514    first_cpu = cpumask_first(cpu_online_mask);
515    /*
516     * We take down all of the non-boot CPUs in one shot to avoid races
517     * with the userspace trying to use the CPU hotplug at the same time
518     */
519    cpumask_clear(frozen_cpus);
520
521    printk("Disabling non-boot CPUs ...\n");
522    for_each_online_cpu(cpu) {
523        if (cpu == first_cpu)
524            continue;
525        error = _cpu_down(cpu, 1);
526        if (!error)
527            cpumask_set_cpu(cpu, frozen_cpus);
528        else {
529            printk(KERN_ERR "Error taking CPU%d down: %d\n",
530                cpu, error);
531            break;
532        }
533    }
534
535    if (!error) {
536        BUG_ON(num_online_cpus() > 1);
537        /* Make sure the CPUs won't be enabled by someone else */
538        cpu_hotplug_disabled = 1;
539    } else {
540        printk(KERN_ERR "Non-boot CPUs are not disabled\n");
541    }
542    cpu_maps_update_done();
543    return error;
544}
545
546void __weak arch_enable_nonboot_cpus_begin(void)
547{
548}
549
550void __weak arch_enable_nonboot_cpus_end(void)
551{
552}
553
554void __ref enable_nonboot_cpus(void)
555{
556    int cpu, error;
557
558    /* Allow everyone to use the CPU hotplug again */
559    cpu_maps_update_begin();
560    cpu_hotplug_disabled = 0;
561    if (cpumask_empty(frozen_cpus))
562        goto out;
563
564    printk(KERN_INFO "Enabling non-boot CPUs ...\n");
565
566    arch_enable_nonboot_cpus_begin();
567
568    for_each_cpu(cpu, frozen_cpus) {
569        error = _cpu_up(cpu, 1);
570        if (!error) {
571            printk(KERN_INFO "CPU%d is up\n", cpu);
572            continue;
573        }
574        printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
575    }
576
577    arch_enable_nonboot_cpus_end();
578
579    cpumask_clear(frozen_cpus);
580out:
581    cpu_maps_update_done();
582}
583
584static int __init alloc_frozen_cpus(void)
585{
586    if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
587        return -ENOMEM;
588    return 0;
589}
590core_initcall(alloc_frozen_cpus);
591
592/*
593 * When callbacks for CPU hotplug notifications are being executed, we must
594 * ensure that the state of the system with respect to the tasks being frozen
595 * or not, as reported by the notification, remains unchanged *throughout the
596 * duration* of the execution of the callbacks.
597 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
598 *
599 * This synchronization is implemented by mutually excluding regular CPU
600 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
601 * Hibernate notifications.
602 */
603static int
604cpu_hotplug_pm_callback(struct notifier_block *nb,
605            unsigned long action, void *ptr)
606{
607    switch (action) {
608
609    case PM_SUSPEND_PREPARE:
610    case PM_HIBERNATION_PREPARE:
611        cpu_hotplug_disable();
612        break;
613
614    case PM_POST_SUSPEND:
615    case PM_POST_HIBERNATION:
616        cpu_hotplug_enable();
617        break;
618
619    default:
620        return NOTIFY_DONE;
621    }
622
623    return NOTIFY_OK;
624}
625
626
627static int __init cpu_hotplug_pm_sync_init(void)
628{
629    /*
630     * cpu_hotplug_pm_callback has higher priority than x86
631     * bsp_pm_callback which depends on cpu_hotplug_pm_callback
632     * to disable cpu hotplug to avoid cpu hotplug race.
633     */
634    pm_notifier(cpu_hotplug_pm_callback, 0);
635    return 0;
636}
637core_initcall(cpu_hotplug_pm_sync_init);
638
639#endif /* CONFIG_PM_SLEEP_SMP */
640
641/**
642 * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
643 * @cpu: cpu that just started
644 *
645 * This function calls the cpu_chain notifiers with CPU_STARTING.
646 * It must be called by the arch code on the new cpu, before the new cpu
647 * enables interrupts and before the "boot" cpu returns from __cpu_up().
648 */
649void notify_cpu_starting(unsigned int cpu)
650{
651    unsigned long val = CPU_STARTING;
652
653#ifdef CONFIG_PM_SLEEP_SMP
654    if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
655        val = CPU_STARTING_FROZEN;
656#endif /* CONFIG_PM_SLEEP_SMP */
657    cpu_notify(val, (void *)(long)cpu);
658}
659
660#endif /* CONFIG_SMP */
661
662/*
663 * cpu_bit_bitmap[] is a special, "compressed" data structure that
664 * represents all NR_CPUS bits binary values of 1<<nr.
665 *
666 * It is used by cpumask_of() to get a constant address to a CPU
667 * mask value that has a single bit set only.
668 */
669
670/* cpu_bit_bitmap[0] is empty - so we can back into it */
671#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
672#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
673#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
674#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
675
676const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
677
678    MASK_DECLARE_8(0), MASK_DECLARE_8(8),
679    MASK_DECLARE_8(16), MASK_DECLARE_8(24),
680#if BITS_PER_LONG > 32
681    MASK_DECLARE_8(32), MASK_DECLARE_8(40),
682    MASK_DECLARE_8(48), MASK_DECLARE_8(56),
683#endif
684};
685EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
686
687const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
688EXPORT_SYMBOL(cpu_all_bits);
689
690#ifdef CONFIG_INIT_ALL_POSSIBLE
691static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
692    = CPU_BITS_ALL;
693#else
694static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
695#endif
696const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
697EXPORT_SYMBOL(cpu_possible_mask);
698
699static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
700const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
701EXPORT_SYMBOL(cpu_online_mask);
702
703static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
704const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
705EXPORT_SYMBOL(cpu_present_mask);
706
707static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
708const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
709EXPORT_SYMBOL(cpu_active_mask);
710
711void set_cpu_possible(unsigned int cpu, bool possible)
712{
713    if (possible)
714        cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
715    else
716        cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
717}
718
719void set_cpu_present(unsigned int cpu, bool present)
720{
721    if (present)
722        cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
723    else
724        cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
725}
726
727void set_cpu_online(unsigned int cpu, bool online)
728{
729    if (online) {
730        cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
731        cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
732    } else {
733        cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
734    }
735}
736
737void set_cpu_active(unsigned int cpu, bool active)
738{
739    if (active)
740        cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
741    else
742        cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
743}
744
745void init_cpu_present(const struct cpumask *src)
746{
747    cpumask_copy(to_cpumask(cpu_present_bits), src);
748}
749
750void init_cpu_possible(const struct cpumask *src)
751{
752    cpumask_copy(to_cpumask(cpu_possible_bits), src);
753}
754
755void init_cpu_online(const struct cpumask *src)
756{
757    cpumask_copy(to_cpumask(cpu_online_bits), src);
758}
759

Archive Download this file



interactive