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

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