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Linux/kernel/time/posix-cpu-timers.c

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  1 /*
  2  * Implement CPU time clocks for the POSIX clock interface.
  3  */
  4 
  5 #include <linux/sched.h>
  6 #include <linux/posix-timers.h>
  7 #include <linux/errno.h>
  8 #include <linux/math64.h>
  9 #include <asm/uaccess.h>
 10 #include <linux/kernel_stat.h>
 11 #include <trace/events/timer.h>
 12 #include <linux/random.h>
 13 #include <linux/tick.h>
 14 #include <linux/workqueue.h>
 15 
 16 /*
 17  * Called after updating RLIMIT_CPU to run cpu timer and update
 18  * tsk->signal->cputime_expires expiration cache if necessary. Needs
 19  * siglock protection since other code may update expiration cache as
 20  * well.
 21  */
 22 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
 23 {
 24         cputime_t cputime = secs_to_cputime(rlim_new);
 25 
 26         spin_lock_irq(&task->sighand->siglock);
 27         set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
 28         spin_unlock_irq(&task->sighand->siglock);
 29 }
 30 
 31 static int check_clock(const clockid_t which_clock)
 32 {
 33         int error = 0;
 34         struct task_struct *p;
 35         const pid_t pid = CPUCLOCK_PID(which_clock);
 36 
 37         if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
 38                 return -EINVAL;
 39 
 40         if (pid == 0)
 41                 return 0;
 42 
 43         rcu_read_lock();
 44         p = find_task_by_vpid(pid);
 45         if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
 46                    same_thread_group(p, current) : has_group_leader_pid(p))) {
 47                 error = -EINVAL;
 48         }
 49         rcu_read_unlock();
 50 
 51         return error;
 52 }
 53 
 54 static inline unsigned long long
 55 timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
 56 {
 57         unsigned long long ret;
 58 
 59         ret = 0;                /* high half always zero when .cpu used */
 60         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 61                 ret = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
 62         } else {
 63                 ret = cputime_to_expires(timespec_to_cputime(tp));
 64         }
 65         return ret;
 66 }
 67 
 68 static void sample_to_timespec(const clockid_t which_clock,
 69                                unsigned long long expires,
 70                                struct timespec *tp)
 71 {
 72         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED)
 73                 *tp = ns_to_timespec(expires);
 74         else
 75                 cputime_to_timespec((__force cputime_t)expires, tp);
 76 }
 77 
 78 /*
 79  * Update expiry time from increment, and increase overrun count,
 80  * given the current clock sample.
 81  */
 82 static void bump_cpu_timer(struct k_itimer *timer,
 83                            unsigned long long now)
 84 {
 85         int i;
 86         unsigned long long delta, incr;
 87 
 88         if (timer->it.cpu.incr == 0)
 89                 return;
 90 
 91         if (now < timer->it.cpu.expires)
 92                 return;
 93 
 94         incr = timer->it.cpu.incr;
 95         delta = now + incr - timer->it.cpu.expires;
 96 
 97         /* Don't use (incr*2 < delta), incr*2 might overflow. */
 98         for (i = 0; incr < delta - incr; i++)
 99                 incr = incr << 1;
100 
101         for (; i >= 0; incr >>= 1, i--) {
102                 if (delta < incr)
103                         continue;
104 
105                 timer->it.cpu.expires += incr;
106                 timer->it_overrun += 1 << i;
107                 delta -= incr;
108         }
109 }
110 
111 /**
112  * task_cputime_zero - Check a task_cputime struct for all zero fields.
113  *
114  * @cputime:    The struct to compare.
115  *
116  * Checks @cputime to see if all fields are zero.  Returns true if all fields
117  * are zero, false if any field is nonzero.
118  */
119 static inline int task_cputime_zero(const struct task_cputime *cputime)
120 {
121         if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
122                 return 1;
123         return 0;
124 }
125 
126 static inline unsigned long long prof_ticks(struct task_struct *p)
127 {
128         cputime_t utime, stime;
129 
130         task_cputime(p, &utime, &stime);
131 
132         return cputime_to_expires(utime + stime);
133 }
134 static inline unsigned long long virt_ticks(struct task_struct *p)
135 {
136         cputime_t utime;
137 
138         task_cputime(p, &utime, NULL);
139 
140         return cputime_to_expires(utime);
141 }
142 
143 static int
144 posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
145 {
146         int error = check_clock(which_clock);
147         if (!error) {
148                 tp->tv_sec = 0;
149                 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
150                 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
151                         /*
152                          * If sched_clock is using a cycle counter, we
153                          * don't have any idea of its true resolution
154                          * exported, but it is much more than 1s/HZ.
155                          */
156                         tp->tv_nsec = 1;
157                 }
158         }
159         return error;
160 }
161 
162 static int
163 posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
164 {
165         /*
166          * You can never reset a CPU clock, but we check for other errors
167          * in the call before failing with EPERM.
168          */
169         int error = check_clock(which_clock);
170         if (error == 0) {
171                 error = -EPERM;
172         }
173         return error;
174 }
175 
176 
177 /*
178  * Sample a per-thread clock for the given task.
179  */
180 static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
181                             unsigned long long *sample)
182 {
183         switch (CPUCLOCK_WHICH(which_clock)) {
184         default:
185                 return -EINVAL;
186         case CPUCLOCK_PROF:
187                 *sample = prof_ticks(p);
188                 break;
189         case CPUCLOCK_VIRT:
190                 *sample = virt_ticks(p);
191                 break;
192         case CPUCLOCK_SCHED:
193                 *sample = task_sched_runtime(p);
194                 break;
195         }
196         return 0;
197 }
198 
199 static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
200 {
201         if (b->utime > a->utime)
202                 a->utime = b->utime;
203 
204         if (b->stime > a->stime)
205                 a->stime = b->stime;
206 
207         if (b->sum_exec_runtime > a->sum_exec_runtime)
208                 a->sum_exec_runtime = b->sum_exec_runtime;
209 }
210 
211 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
212 {
213         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
214         struct task_cputime sum;
215         unsigned long flags;
216 
217         if (!cputimer->running) {
218                 /*
219                  * The POSIX timer interface allows for absolute time expiry
220                  * values through the TIMER_ABSTIME flag, therefore we have
221                  * to synchronize the timer to the clock every time we start
222                  * it.
223                  */
224                 thread_group_cputime(tsk, &sum);
225                 raw_spin_lock_irqsave(&cputimer->lock, flags);
226                 cputimer->running = 1;
227                 update_gt_cputime(&cputimer->cputime, &sum);
228         } else
229                 raw_spin_lock_irqsave(&cputimer->lock, flags);
230         *times = cputimer->cputime;
231         raw_spin_unlock_irqrestore(&cputimer->lock, flags);
232 }
233 
234 /*
235  * Sample a process (thread group) clock for the given group_leader task.
236  * Must be called with task sighand lock held for safe while_each_thread()
237  * traversal.
238  */
239 static int cpu_clock_sample_group(const clockid_t which_clock,
240                                   struct task_struct *p,
241                                   unsigned long long *sample)
242 {
243         struct task_cputime cputime;
244 
245         switch (CPUCLOCK_WHICH(which_clock)) {
246         default:
247                 return -EINVAL;
248         case CPUCLOCK_PROF:
249                 thread_group_cputime(p, &cputime);
250                 *sample = cputime_to_expires(cputime.utime + cputime.stime);
251                 break;
252         case CPUCLOCK_VIRT:
253                 thread_group_cputime(p, &cputime);
254                 *sample = cputime_to_expires(cputime.utime);
255                 break;
256         case CPUCLOCK_SCHED:
257                 thread_group_cputime(p, &cputime);
258                 *sample = cputime.sum_exec_runtime;
259                 break;
260         }
261         return 0;
262 }
263 
264 static int posix_cpu_clock_get_task(struct task_struct *tsk,
265                                     const clockid_t which_clock,
266                                     struct timespec *tp)
267 {
268         int err = -EINVAL;
269         unsigned long long rtn;
270 
271         if (CPUCLOCK_PERTHREAD(which_clock)) {
272                 if (same_thread_group(tsk, current))
273                         err = cpu_clock_sample(which_clock, tsk, &rtn);
274         } else {
275                 if (tsk == current || thread_group_leader(tsk))
276                         err = cpu_clock_sample_group(which_clock, tsk, &rtn);
277         }
278 
279         if (!err)
280                 sample_to_timespec(which_clock, rtn, tp);
281 
282         return err;
283 }
284 
285 
286 static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
287 {
288         const pid_t pid = CPUCLOCK_PID(which_clock);
289         int err = -EINVAL;
290 
291         if (pid == 0) {
292                 /*
293                  * Special case constant value for our own clocks.
294                  * We don't have to do any lookup to find ourselves.
295                  */
296                 err = posix_cpu_clock_get_task(current, which_clock, tp);
297         } else {
298                 /*
299                  * Find the given PID, and validate that the caller
300                  * should be able to see it.
301                  */
302                 struct task_struct *p;
303                 rcu_read_lock();
304                 p = find_task_by_vpid(pid);
305                 if (p)
306                         err = posix_cpu_clock_get_task(p, which_clock, tp);
307                 rcu_read_unlock();
308         }
309 
310         return err;
311 }
312 
313 
314 /*
315  * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
316  * This is called from sys_timer_create() and do_cpu_nanosleep() with the
317  * new timer already all-zeros initialized.
318  */
319 static int posix_cpu_timer_create(struct k_itimer *new_timer)
320 {
321         int ret = 0;
322         const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
323         struct task_struct *p;
324 
325         if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
326                 return -EINVAL;
327 
328         INIT_LIST_HEAD(&new_timer->it.cpu.entry);
329 
330         rcu_read_lock();
331         if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
332                 if (pid == 0) {
333                         p = current;
334                 } else {
335                         p = find_task_by_vpid(pid);
336                         if (p && !same_thread_group(p, current))
337                                 p = NULL;
338                 }
339         } else {
340                 if (pid == 0) {
341                         p = current->group_leader;
342                 } else {
343                         p = find_task_by_vpid(pid);
344                         if (p && !has_group_leader_pid(p))
345                                 p = NULL;
346                 }
347         }
348         new_timer->it.cpu.task = p;
349         if (p) {
350                 get_task_struct(p);
351         } else {
352                 ret = -EINVAL;
353         }
354         rcu_read_unlock();
355 
356         return ret;
357 }
358 
359 /*
360  * Clean up a CPU-clock timer that is about to be destroyed.
361  * This is called from timer deletion with the timer already locked.
362  * If we return TIMER_RETRY, it's necessary to release the timer's lock
363  * and try again.  (This happens when the timer is in the middle of firing.)
364  */
365 static int posix_cpu_timer_del(struct k_itimer *timer)
366 {
367         int ret = 0;
368         unsigned long flags;
369         struct sighand_struct *sighand;
370         struct task_struct *p = timer->it.cpu.task;
371 
372         WARN_ON_ONCE(p == NULL);
373 
374         /*
375          * Protect against sighand release/switch in exit/exec and process/
376          * thread timer list entry concurrent read/writes.
377          */
378         sighand = lock_task_sighand(p, &flags);
379         if (unlikely(sighand == NULL)) {
380                 /*
381                  * We raced with the reaping of the task.
382                  * The deletion should have cleared us off the list.
383                  */
384                 WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry));
385         } else {
386                 if (timer->it.cpu.firing)
387                         ret = TIMER_RETRY;
388                 else
389                         list_del(&timer->it.cpu.entry);
390 
391                 unlock_task_sighand(p, &flags);
392         }
393 
394         if (!ret)
395                 put_task_struct(p);
396 
397         return ret;
398 }
399 
400 static void cleanup_timers_list(struct list_head *head)
401 {
402         struct cpu_timer_list *timer, *next;
403 
404         list_for_each_entry_safe(timer, next, head, entry)
405                 list_del_init(&timer->entry);
406 }
407 
408 /*
409  * Clean out CPU timers still ticking when a thread exited.  The task
410  * pointer is cleared, and the expiry time is replaced with the residual
411  * time for later timer_gettime calls to return.
412  * This must be called with the siglock held.
413  */
414 static void cleanup_timers(struct list_head *head)
415 {
416         cleanup_timers_list(head);
417         cleanup_timers_list(++head);
418         cleanup_timers_list(++head);
419 }
420 
421 /*
422  * These are both called with the siglock held, when the current thread
423  * is being reaped.  When the final (leader) thread in the group is reaped,
424  * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
425  */
426 void posix_cpu_timers_exit(struct task_struct *tsk)
427 {
428         add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
429                                                 sizeof(unsigned long long));
430         cleanup_timers(tsk->cpu_timers);
431 
432 }
433 void posix_cpu_timers_exit_group(struct task_struct *tsk)
434 {
435         cleanup_timers(tsk->signal->cpu_timers);
436 }
437 
438 static inline int expires_gt(cputime_t expires, cputime_t new_exp)
439 {
440         return expires == 0 || expires > new_exp;
441 }
442 
443 /*
444  * Insert the timer on the appropriate list before any timers that
445  * expire later.  This must be called with the sighand lock held.
446  */
447 static void arm_timer(struct k_itimer *timer)
448 {
449         struct task_struct *p = timer->it.cpu.task;
450         struct list_head *head, *listpos;
451         struct task_cputime *cputime_expires;
452         struct cpu_timer_list *const nt = &timer->it.cpu;
453         struct cpu_timer_list *next;
454 
455         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
456                 head = p->cpu_timers;
457                 cputime_expires = &p->cputime_expires;
458         } else {
459                 head = p->signal->cpu_timers;
460                 cputime_expires = &p->signal->cputime_expires;
461         }
462         head += CPUCLOCK_WHICH(timer->it_clock);
463 
464         listpos = head;
465         list_for_each_entry(next, head, entry) {
466                 if (nt->expires < next->expires)
467                         break;
468                 listpos = &next->entry;
469         }
470         list_add(&nt->entry, listpos);
471 
472         if (listpos == head) {
473                 unsigned long long exp = nt->expires;
474 
475                 /*
476                  * We are the new earliest-expiring POSIX 1.b timer, hence
477                  * need to update expiration cache. Take into account that
478                  * for process timers we share expiration cache with itimers
479                  * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
480                  */
481 
482                 switch (CPUCLOCK_WHICH(timer->it_clock)) {
483                 case CPUCLOCK_PROF:
484                         if (expires_gt(cputime_expires->prof_exp, expires_to_cputime(exp)))
485                                 cputime_expires->prof_exp = expires_to_cputime(exp);
486                         break;
487                 case CPUCLOCK_VIRT:
488                         if (expires_gt(cputime_expires->virt_exp, expires_to_cputime(exp)))
489                                 cputime_expires->virt_exp = expires_to_cputime(exp);
490                         break;
491                 case CPUCLOCK_SCHED:
492                         if (cputime_expires->sched_exp == 0 ||
493                             cputime_expires->sched_exp > exp)
494                                 cputime_expires->sched_exp = exp;
495                         break;
496                 }
497         }
498 }
499 
500 /*
501  * The timer is locked, fire it and arrange for its reload.
502  */
503 static void cpu_timer_fire(struct k_itimer *timer)
504 {
505         if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
506                 /*
507                  * User don't want any signal.
508                  */
509                 timer->it.cpu.expires = 0;
510         } else if (unlikely(timer->sigq == NULL)) {
511                 /*
512                  * This a special case for clock_nanosleep,
513                  * not a normal timer from sys_timer_create.
514                  */
515                 wake_up_process(timer->it_process);
516                 timer->it.cpu.expires = 0;
517         } else if (timer->it.cpu.incr == 0) {
518                 /*
519                  * One-shot timer.  Clear it as soon as it's fired.
520                  */
521                 posix_timer_event(timer, 0);
522                 timer->it.cpu.expires = 0;
523         } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
524                 /*
525                  * The signal did not get queued because the signal
526                  * was ignored, so we won't get any callback to
527                  * reload the timer.  But we need to keep it
528                  * ticking in case the signal is deliverable next time.
529                  */
530                 posix_cpu_timer_schedule(timer);
531         }
532 }
533 
534 /*
535  * Sample a process (thread group) timer for the given group_leader task.
536  * Must be called with task sighand lock held for safe while_each_thread()
537  * traversal.
538  */
539 static int cpu_timer_sample_group(const clockid_t which_clock,
540                                   struct task_struct *p,
541                                   unsigned long long *sample)
542 {
543         struct task_cputime cputime;
544 
545         thread_group_cputimer(p, &cputime);
546         switch (CPUCLOCK_WHICH(which_clock)) {
547         default:
548                 return -EINVAL;
549         case CPUCLOCK_PROF:
550                 *sample = cputime_to_expires(cputime.utime + cputime.stime);
551                 break;
552         case CPUCLOCK_VIRT:
553                 *sample = cputime_to_expires(cputime.utime);
554                 break;
555         case CPUCLOCK_SCHED:
556                 *sample = cputime.sum_exec_runtime;
557                 break;
558         }
559         return 0;
560 }
561 
562 #ifdef CONFIG_NO_HZ_FULL
563 static void nohz_kick_work_fn(struct work_struct *work)
564 {
565         tick_nohz_full_kick_all();
566 }
567 
568 static DECLARE_WORK(nohz_kick_work, nohz_kick_work_fn);
569 
570 /*
571  * We need the IPIs to be sent from sane process context.
572  * The posix cpu timers are always set with irqs disabled.
573  */
574 static void posix_cpu_timer_kick_nohz(void)
575 {
576         if (context_tracking_is_enabled())
577                 schedule_work(&nohz_kick_work);
578 }
579 
580 bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk)
581 {
582         if (!task_cputime_zero(&tsk->cputime_expires))
583                 return false;
584 
585         if (tsk->signal->cputimer.running)
586                 return false;
587 
588         return true;
589 }
590 #else
591 static inline void posix_cpu_timer_kick_nohz(void) { }
592 #endif
593 
594 /*
595  * Guts of sys_timer_settime for CPU timers.
596  * This is called with the timer locked and interrupts disabled.
597  * If we return TIMER_RETRY, it's necessary to release the timer's lock
598  * and try again.  (This happens when the timer is in the middle of firing.)
599  */
600 static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
601                                struct itimerspec *new, struct itimerspec *old)
602 {
603         unsigned long flags;
604         struct sighand_struct *sighand;
605         struct task_struct *p = timer->it.cpu.task;
606         unsigned long long old_expires, new_expires, old_incr, val;
607         int ret;
608 
609         WARN_ON_ONCE(p == NULL);
610 
611         new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
612 
613         /*
614          * Protect against sighand release/switch in exit/exec and p->cpu_timers
615          * and p->signal->cpu_timers read/write in arm_timer()
616          */
617         sighand = lock_task_sighand(p, &flags);
618         /*
619          * If p has just been reaped, we can no
620          * longer get any information about it at all.
621          */
622         if (unlikely(sighand == NULL)) {
623                 return -ESRCH;
624         }
625 
626         /*
627          * Disarm any old timer after extracting its expiry time.
628          */
629         WARN_ON_ONCE(!irqs_disabled());
630 
631         ret = 0;
632         old_incr = timer->it.cpu.incr;
633         old_expires = timer->it.cpu.expires;
634         if (unlikely(timer->it.cpu.firing)) {
635                 timer->it.cpu.firing = -1;
636                 ret = TIMER_RETRY;
637         } else
638                 list_del_init(&timer->it.cpu.entry);
639 
640         /*
641          * We need to sample the current value to convert the new
642          * value from to relative and absolute, and to convert the
643          * old value from absolute to relative.  To set a process
644          * timer, we need a sample to balance the thread expiry
645          * times (in arm_timer).  With an absolute time, we must
646          * check if it's already passed.  In short, we need a sample.
647          */
648         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
649                 cpu_clock_sample(timer->it_clock, p, &val);
650         } else {
651                 cpu_timer_sample_group(timer->it_clock, p, &val);
652         }
653 
654         if (old) {
655                 if (old_expires == 0) {
656                         old->it_value.tv_sec = 0;
657                         old->it_value.tv_nsec = 0;
658                 } else {
659                         /*
660                          * Update the timer in case it has
661                          * overrun already.  If it has,
662                          * we'll report it as having overrun
663                          * and with the next reloaded timer
664                          * already ticking, though we are
665                          * swallowing that pending
666                          * notification here to install the
667                          * new setting.
668                          */
669                         bump_cpu_timer(timer, val);
670                         if (val < timer->it.cpu.expires) {
671                                 old_expires = timer->it.cpu.expires - val;
672                                 sample_to_timespec(timer->it_clock,
673                                                    old_expires,
674                                                    &old->it_value);
675                         } else {
676                                 old->it_value.tv_nsec = 1;
677                                 old->it_value.tv_sec = 0;
678                         }
679                 }
680         }
681 
682         if (unlikely(ret)) {
683                 /*
684                  * We are colliding with the timer actually firing.
685                  * Punt after filling in the timer's old value, and
686                  * disable this firing since we are already reporting
687                  * it as an overrun (thanks to bump_cpu_timer above).
688                  */
689                 unlock_task_sighand(p, &flags);
690                 goto out;
691         }
692 
693         if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) {
694                 new_expires += val;
695         }
696 
697         /*
698          * Install the new expiry time (or zero).
699          * For a timer with no notification action, we don't actually
700          * arm the timer (we'll just fake it for timer_gettime).
701          */
702         timer->it.cpu.expires = new_expires;
703         if (new_expires != 0 && val < new_expires) {
704                 arm_timer(timer);
705         }
706 
707         unlock_task_sighand(p, &flags);
708         /*
709          * Install the new reload setting, and
710          * set up the signal and overrun bookkeeping.
711          */
712         timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
713                                                 &new->it_interval);
714 
715         /*
716          * This acts as a modification timestamp for the timer,
717          * so any automatic reload attempt will punt on seeing
718          * that we have reset the timer manually.
719          */
720         timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
721                 ~REQUEUE_PENDING;
722         timer->it_overrun_last = 0;
723         timer->it_overrun = -1;
724 
725         if (new_expires != 0 && !(val < new_expires)) {
726                 /*
727                  * The designated time already passed, so we notify
728                  * immediately, even if the thread never runs to
729                  * accumulate more time on this clock.
730                  */
731                 cpu_timer_fire(timer);
732         }
733 
734         ret = 0;
735  out:
736         if (old) {
737                 sample_to_timespec(timer->it_clock,
738                                    old_incr, &old->it_interval);
739         }
740         if (!ret)
741                 posix_cpu_timer_kick_nohz();
742         return ret;
743 }
744 
745 static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
746 {
747         unsigned long long now;
748         struct task_struct *p = timer->it.cpu.task;
749 
750         WARN_ON_ONCE(p == NULL);
751 
752         /*
753          * Easy part: convert the reload time.
754          */
755         sample_to_timespec(timer->it_clock,
756                            timer->it.cpu.incr, &itp->it_interval);
757 
758         if (timer->it.cpu.expires == 0) {       /* Timer not armed at all.  */
759                 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
760                 return;
761         }
762 
763         /*
764          * Sample the clock to take the difference with the expiry time.
765          */
766         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
767                 cpu_clock_sample(timer->it_clock, p, &now);
768         } else {
769                 struct sighand_struct *sighand;
770                 unsigned long flags;
771 
772                 /*
773                  * Protect against sighand release/switch in exit/exec and
774                  * also make timer sampling safe if it ends up calling
775                  * thread_group_cputime().
776                  */
777                 sighand = lock_task_sighand(p, &flags);
778                 if (unlikely(sighand == NULL)) {
779                         /*
780                          * The process has been reaped.
781                          * We can't even collect a sample any more.
782                          * Call the timer disarmed, nothing else to do.
783                          */
784                         timer->it.cpu.expires = 0;
785                         sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
786                                            &itp->it_value);
787                         return;
788                 } else {
789                         cpu_timer_sample_group(timer->it_clock, p, &now);
790                         unlock_task_sighand(p, &flags);
791                 }
792         }
793 
794         if (now < timer->it.cpu.expires) {
795                 sample_to_timespec(timer->it_clock,
796                                    timer->it.cpu.expires - now,
797                                    &itp->it_value);
798         } else {
799                 /*
800                  * The timer should have expired already, but the firing
801                  * hasn't taken place yet.  Say it's just about to expire.
802                  */
803                 itp->it_value.tv_nsec = 1;
804                 itp->it_value.tv_sec = 0;
805         }
806 }
807 
808 static unsigned long long
809 check_timers_list(struct list_head *timers,
810                   struct list_head *firing,
811                   unsigned long long curr)
812 {
813         int maxfire = 20;
814 
815         while (!list_empty(timers)) {
816                 struct cpu_timer_list *t;
817 
818                 t = list_first_entry(timers, struct cpu_timer_list, entry);
819 
820                 if (!--maxfire || curr < t->expires)
821                         return t->expires;
822 
823                 t->firing = 1;
824                 list_move_tail(&t->entry, firing);
825         }
826 
827         return 0;
828 }
829 
830 /*
831  * Check for any per-thread CPU timers that have fired and move them off
832  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
833  * tsk->it_*_expires values to reflect the remaining thread CPU timers.
834  */
835 static void check_thread_timers(struct task_struct *tsk,
836                                 struct list_head *firing)
837 {
838         struct list_head *timers = tsk->cpu_timers;
839         struct signal_struct *const sig = tsk->signal;
840         struct task_cputime *tsk_expires = &tsk->cputime_expires;
841         unsigned long long expires;
842         unsigned long soft;
843 
844         expires = check_timers_list(timers, firing, prof_ticks(tsk));
845         tsk_expires->prof_exp = expires_to_cputime(expires);
846 
847         expires = check_timers_list(++timers, firing, virt_ticks(tsk));
848         tsk_expires->virt_exp = expires_to_cputime(expires);
849 
850         tsk_expires->sched_exp = check_timers_list(++timers, firing,
851                                                    tsk->se.sum_exec_runtime);
852 
853         /*
854          * Check for the special case thread timers.
855          */
856         soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
857         if (soft != RLIM_INFINITY) {
858                 unsigned long hard =
859                         ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
860 
861                 if (hard != RLIM_INFINITY &&
862                     tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
863                         /*
864                          * At the hard limit, we just die.
865                          * No need to calculate anything else now.
866                          */
867                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
868                         return;
869                 }
870                 if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
871                         /*
872                          * At the soft limit, send a SIGXCPU every second.
873                          */
874                         if (soft < hard) {
875                                 soft += USEC_PER_SEC;
876                                 sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
877                         }
878                         printk(KERN_INFO
879                                 "RT Watchdog Timeout: %s[%d]\n",
880                                 tsk->comm, task_pid_nr(tsk));
881                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
882                 }
883         }
884 }
885 
886 static void stop_process_timers(struct signal_struct *sig)
887 {
888         struct thread_group_cputimer *cputimer = &sig->cputimer;
889         unsigned long flags;
890 
891         raw_spin_lock_irqsave(&cputimer->lock, flags);
892         cputimer->running = 0;
893         raw_spin_unlock_irqrestore(&cputimer->lock, flags);
894 }
895 
896 static u32 onecputick;
897 
898 static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
899                              unsigned long long *expires,
900                              unsigned long long cur_time, int signo)
901 {
902         if (!it->expires)
903                 return;
904 
905         if (cur_time >= it->expires) {
906                 if (it->incr) {
907                         it->expires += it->incr;
908                         it->error += it->incr_error;
909                         if (it->error >= onecputick) {
910                                 it->expires -= cputime_one_jiffy;
911                                 it->error -= onecputick;
912                         }
913                 } else {
914                         it->expires = 0;
915                 }
916 
917                 trace_itimer_expire(signo == SIGPROF ?
918                                     ITIMER_PROF : ITIMER_VIRTUAL,
919                                     tsk->signal->leader_pid, cur_time);
920                 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
921         }
922 
923         if (it->expires && (!*expires || it->expires < *expires)) {
924                 *expires = it->expires;
925         }
926 }
927 
928 /*
929  * Check for any per-thread CPU timers that have fired and move them
930  * off the tsk->*_timers list onto the firing list.  Per-thread timers
931  * have already been taken off.
932  */
933 static void check_process_timers(struct task_struct *tsk,
934                                  struct list_head *firing)
935 {
936         struct signal_struct *const sig = tsk->signal;
937         unsigned long long utime, ptime, virt_expires, prof_expires;
938         unsigned long long sum_sched_runtime, sched_expires;
939         struct list_head *timers = sig->cpu_timers;
940         struct task_cputime cputime;
941         unsigned long soft;
942 
943         /*
944          * Collect the current process totals.
945          */
946         thread_group_cputimer(tsk, &cputime);
947         utime = cputime_to_expires(cputime.utime);
948         ptime = utime + cputime_to_expires(cputime.stime);
949         sum_sched_runtime = cputime.sum_exec_runtime;
950 
951         prof_expires = check_timers_list(timers, firing, ptime);
952         virt_expires = check_timers_list(++timers, firing, utime);
953         sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);
954 
955         /*
956          * Check for the special case process timers.
957          */
958         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
959                          SIGPROF);
960         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
961                          SIGVTALRM);
962         soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
963         if (soft != RLIM_INFINITY) {
964                 unsigned long psecs = cputime_to_secs(ptime);
965                 unsigned long hard =
966                         ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
967                 cputime_t x;
968                 if (psecs >= hard) {
969                         /*
970                          * At the hard limit, we just die.
971                          * No need to calculate anything else now.
972                          */
973                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
974                         return;
975                 }
976                 if (psecs >= soft) {
977                         /*
978                          * At the soft limit, send a SIGXCPU every second.
979                          */
980                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
981                         if (soft < hard) {
982                                 soft++;
983                                 sig->rlim[RLIMIT_CPU].rlim_cur = soft;
984                         }
985                 }
986                 x = secs_to_cputime(soft);
987                 if (!prof_expires || x < prof_expires) {
988                         prof_expires = x;
989                 }
990         }
991 
992         sig->cputime_expires.prof_exp = expires_to_cputime(prof_expires);
993         sig->cputime_expires.virt_exp = expires_to_cputime(virt_expires);
994         sig->cputime_expires.sched_exp = sched_expires;
995         if (task_cputime_zero(&sig->cputime_expires))
996                 stop_process_timers(sig);
997 }
998 
999 /*
1000  * This is called from the signal code (via do_schedule_next_timer)
1001  * when the last timer signal was delivered and we have to reload the timer.
1002  */
1003 void posix_cpu_timer_schedule(struct k_itimer *timer)
1004 {
1005         struct sighand_struct *sighand;
1006         unsigned long flags;
1007         struct task_struct *p = timer->it.cpu.task;
1008         unsigned long long now;
1009 
1010         WARN_ON_ONCE(p == NULL);
1011 
1012         /*
1013          * Fetch the current sample and update the timer's expiry time.
1014          */
1015         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1016                 cpu_clock_sample(timer->it_clock, p, &now);
1017                 bump_cpu_timer(timer, now);
1018                 if (unlikely(p->exit_state))
1019                         goto out;
1020 
1021                 /* Protect timer list r/w in arm_timer() */
1022                 sighand = lock_task_sighand(p, &flags);
1023                 if (!sighand)
1024                         goto out;
1025         } else {
1026                 /*
1027                  * Protect arm_timer() and timer sampling in case of call to
1028                  * thread_group_cputime().
1029                  */
1030                 sighand = lock_task_sighand(p, &flags);
1031                 if (unlikely(sighand == NULL)) {
1032                         /*
1033                          * The process has been reaped.
1034                          * We can't even collect a sample any more.
1035                          */
1036                         timer->it.cpu.expires = 0;
1037                         goto out;
1038                 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1039                         unlock_task_sighand(p, &flags);
1040                         /* Optimizations: if the process is dying, no need to rearm */
1041                         goto out;
1042                 }
1043                 cpu_timer_sample_group(timer->it_clock, p, &now);
1044                 bump_cpu_timer(timer, now);
1045                 /* Leave the sighand locked for the call below.  */
1046         }
1047 
1048         /*
1049          * Now re-arm for the new expiry time.
1050          */
1051         WARN_ON_ONCE(!irqs_disabled());
1052         arm_timer(timer);
1053         unlock_task_sighand(p, &flags);
1054 
1055         /* Kick full dynticks CPUs in case they need to tick on the new timer */
1056         posix_cpu_timer_kick_nohz();
1057 out:
1058         timer->it_overrun_last = timer->it_overrun;
1059         timer->it_overrun = -1;
1060         ++timer->it_requeue_pending;
1061 }
1062 
1063 /**
1064  * task_cputime_expired - Compare two task_cputime entities.
1065  *
1066  * @sample:     The task_cputime structure to be checked for expiration.
1067  * @expires:    Expiration times, against which @sample will be checked.
1068  *
1069  * Checks @sample against @expires to see if any field of @sample has expired.
1070  * Returns true if any field of the former is greater than the corresponding
1071  * field of the latter if the latter field is set.  Otherwise returns false.
1072  */
1073 static inline int task_cputime_expired(const struct task_cputime *sample,
1074                                         const struct task_cputime *expires)
1075 {
1076         if (expires->utime && sample->utime >= expires->utime)
1077                 return 1;
1078         if (expires->stime && sample->utime + sample->stime >= expires->stime)
1079                 return 1;
1080         if (expires->sum_exec_runtime != 0 &&
1081             sample->sum_exec_runtime >= expires->sum_exec_runtime)
1082                 return 1;
1083         return 0;
1084 }
1085 
1086 /**
1087  * fastpath_timer_check - POSIX CPU timers fast path.
1088  *
1089  * @tsk:        The task (thread) being checked.
1090  *
1091  * Check the task and thread group timers.  If both are zero (there are no
1092  * timers set) return false.  Otherwise snapshot the task and thread group
1093  * timers and compare them with the corresponding expiration times.  Return
1094  * true if a timer has expired, else return false.
1095  */
1096 static inline int fastpath_timer_check(struct task_struct *tsk)
1097 {
1098         struct signal_struct *sig;
1099         cputime_t utime, stime;
1100 
1101         task_cputime(tsk, &utime, &stime);
1102 
1103         if (!task_cputime_zero(&tsk->cputime_expires)) {
1104                 struct task_cputime task_sample = {
1105                         .utime = utime,
1106                         .stime = stime,
1107                         .sum_exec_runtime = tsk->se.sum_exec_runtime
1108                 };
1109 
1110                 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1111                         return 1;
1112         }
1113 
1114         sig = tsk->signal;
1115         if (sig->cputimer.running) {
1116                 struct task_cputime group_sample;
1117 
1118                 raw_spin_lock(&sig->cputimer.lock);
1119                 group_sample = sig->cputimer.cputime;
1120                 raw_spin_unlock(&sig->cputimer.lock);
1121 
1122                 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1123                         return 1;
1124         }
1125 
1126         return 0;
1127 }
1128 
1129 /*
1130  * This is called from the timer interrupt handler.  The irq handler has
1131  * already updated our counts.  We need to check if any timers fire now.
1132  * Interrupts are disabled.
1133  */
1134 void run_posix_cpu_timers(struct task_struct *tsk)
1135 {
1136         LIST_HEAD(firing);
1137         struct k_itimer *timer, *next;
1138         unsigned long flags;
1139 
1140         WARN_ON_ONCE(!irqs_disabled());
1141 
1142         /*
1143          * The fast path checks that there are no expired thread or thread
1144          * group timers.  If that's so, just return.
1145          */
1146         if (!fastpath_timer_check(tsk))
1147                 return;
1148 
1149         if (!lock_task_sighand(tsk, &flags))
1150                 return;
1151         /*
1152          * Here we take off tsk->signal->cpu_timers[N] and
1153          * tsk->cpu_timers[N] all the timers that are firing, and
1154          * put them on the firing list.
1155          */
1156         check_thread_timers(tsk, &firing);
1157         /*
1158          * If there are any active process wide timers (POSIX 1.b, itimers,
1159          * RLIMIT_CPU) cputimer must be running.
1160          */
1161         if (tsk->signal->cputimer.running)
1162                 check_process_timers(tsk, &firing);
1163 
1164         /*
1165          * We must release these locks before taking any timer's lock.
1166          * There is a potential race with timer deletion here, as the
1167          * siglock now protects our private firing list.  We have set
1168          * the firing flag in each timer, so that a deletion attempt
1169          * that gets the timer lock before we do will give it up and
1170          * spin until we've taken care of that timer below.
1171          */
1172         unlock_task_sighand(tsk, &flags);
1173 
1174         /*
1175          * Now that all the timers on our list have the firing flag,
1176          * no one will touch their list entries but us.  We'll take
1177          * each timer's lock before clearing its firing flag, so no
1178          * timer call will interfere.
1179          */
1180         list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1181                 int cpu_firing;
1182 
1183                 spin_lock(&timer->it_lock);
1184                 list_del_init(&timer->it.cpu.entry);
1185                 cpu_firing = timer->it.cpu.firing;
1186                 timer->it.cpu.firing = 0;
1187                 /*
1188                  * The firing flag is -1 if we collided with a reset
1189                  * of the timer, which already reported this
1190                  * almost-firing as an overrun.  So don't generate an event.
1191                  */
1192                 if (likely(cpu_firing >= 0))
1193                         cpu_timer_fire(timer);
1194                 spin_unlock(&timer->it_lock);
1195         }
1196 }
1197 
1198 /*
1199  * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1200  * The tsk->sighand->siglock must be held by the caller.
1201  */
1202 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1203                            cputime_t *newval, cputime_t *oldval)
1204 {
1205         unsigned long long now;
1206 
1207         WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED);
1208         cpu_timer_sample_group(clock_idx, tsk, &now);
1209 
1210         if (oldval) {
1211                 /*
1212                  * We are setting itimer. The *oldval is absolute and we update
1213                  * it to be relative, *newval argument is relative and we update
1214                  * it to be absolute.
1215                  */
1216                 if (*oldval) {
1217                         if (*oldval <= now) {
1218                                 /* Just about to fire. */
1219                                 *oldval = cputime_one_jiffy;
1220                         } else {
1221                                 *oldval -= now;
1222                         }
1223                 }
1224 
1225                 if (!*newval)
1226                         goto out;
1227                 *newval += now;
1228         }
1229 
1230         /*
1231          * Update expiration cache if we are the earliest timer, or eventually
1232          * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1233          */
1234         switch (clock_idx) {
1235         case CPUCLOCK_PROF:
1236                 if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1237                         tsk->signal->cputime_expires.prof_exp = *newval;
1238                 break;
1239         case CPUCLOCK_VIRT:
1240                 if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1241                         tsk->signal->cputime_expires.virt_exp = *newval;
1242                 break;
1243         }
1244 out:
1245         posix_cpu_timer_kick_nohz();
1246 }
1247 
1248 static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1249                             struct timespec *rqtp, struct itimerspec *it)
1250 {
1251         struct k_itimer timer;
1252         int error;
1253 
1254         /*
1255          * Set up a temporary timer and then wait for it to go off.
1256          */
1257         memset(&timer, 0, sizeof timer);
1258         spin_lock_init(&timer.it_lock);
1259         timer.it_clock = which_clock;
1260         timer.it_overrun = -1;
1261         error = posix_cpu_timer_create(&timer);
1262         timer.it_process = current;
1263         if (!error) {
1264                 static struct itimerspec zero_it;
1265 
1266                 memset(it, 0, sizeof *it);
1267                 it->it_value = *rqtp;
1268 
1269                 spin_lock_irq(&timer.it_lock);
1270                 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1271                 if (error) {
1272                         spin_unlock_irq(&timer.it_lock);
1273                         return error;
1274                 }
1275 
1276                 while (!signal_pending(current)) {
1277                         if (timer.it.cpu.expires == 0) {
1278                                 /*
1279                                  * Our timer fired and was reset, below
1280                                  * deletion can not fail.
1281                                  */
1282                                 posix_cpu_timer_del(&timer);
1283                                 spin_unlock_irq(&timer.it_lock);
1284                                 return 0;
1285                         }
1286 
1287                         /*
1288                          * Block until cpu_timer_fire (or a signal) wakes us.
1289                          */
1290                         __set_current_state(TASK_INTERRUPTIBLE);
1291                         spin_unlock_irq(&timer.it_lock);
1292                         schedule();
1293                         spin_lock_irq(&timer.it_lock);
1294                 }
1295 
1296                 /*
1297                  * We were interrupted by a signal.
1298                  */
1299                 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1300                 error = posix_cpu_timer_set(&timer, 0, &zero_it, it);
1301                 if (!error) {
1302                         /*
1303                          * Timer is now unarmed, deletion can not fail.
1304                          */
1305                         posix_cpu_timer_del(&timer);
1306                 }
1307                 spin_unlock_irq(&timer.it_lock);
1308 
1309                 while (error == TIMER_RETRY) {
1310                         /*
1311                          * We need to handle case when timer was or is in the
1312                          * middle of firing. In other cases we already freed
1313                          * resources.
1314                          */
1315                         spin_lock_irq(&timer.it_lock);
1316                         error = posix_cpu_timer_del(&timer);
1317                         spin_unlock_irq(&timer.it_lock);
1318                 }
1319 
1320                 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1321                         /*
1322                          * It actually did fire already.
1323                          */
1324                         return 0;
1325                 }
1326 
1327                 error = -ERESTART_RESTARTBLOCK;
1328         }
1329 
1330         return error;
1331 }
1332 
1333 static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1334 
1335 static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1336                             struct timespec *rqtp, struct timespec __user *rmtp)
1337 {
1338         struct restart_block *restart_block = &current->restart_block;
1339         struct itimerspec it;
1340         int error;
1341 
1342         /*
1343          * Diagnose required errors first.
1344          */
1345         if (CPUCLOCK_PERTHREAD(which_clock) &&
1346             (CPUCLOCK_PID(which_clock) == 0 ||
1347              CPUCLOCK_PID(which_clock) == current->pid))
1348                 return -EINVAL;
1349 
1350         error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1351 
1352         if (error == -ERESTART_RESTARTBLOCK) {
1353 
1354                 if (flags & TIMER_ABSTIME)
1355                         return -ERESTARTNOHAND;
1356                 /*
1357                  * Report back to the user the time still remaining.
1358                  */
1359                 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1360                         return -EFAULT;
1361 
1362                 restart_block->fn = posix_cpu_nsleep_restart;
1363                 restart_block->nanosleep.clockid = which_clock;
1364                 restart_block->nanosleep.rmtp = rmtp;
1365                 restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1366         }
1367         return error;
1368 }
1369 
1370 static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1371 {
1372         clockid_t which_clock = restart_block->nanosleep.clockid;
1373         struct timespec t;
1374         struct itimerspec it;
1375         int error;
1376 
1377         t = ns_to_timespec(restart_block->nanosleep.expires);
1378 
1379         error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1380 
1381         if (error == -ERESTART_RESTARTBLOCK) {
1382                 struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1383                 /*
1384                  * Report back to the user the time still remaining.
1385                  */
1386                 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1387                         return -EFAULT;
1388 
1389                 restart_block->nanosleep.expires = timespec_to_ns(&t);
1390         }
1391         return error;
1392 
1393 }
1394 
1395 #define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1396 #define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1397 
1398 static int process_cpu_clock_getres(const clockid_t which_clock,
1399                                     struct timespec *tp)
1400 {
1401         return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1402 }
1403 static int process_cpu_clock_get(const clockid_t which_clock,
1404                                  struct timespec *tp)
1405 {
1406         return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1407 }
1408 static int process_cpu_timer_create(struct k_itimer *timer)
1409 {
1410         timer->it_clock = PROCESS_CLOCK;
1411         return posix_cpu_timer_create(timer);
1412 }
1413 static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1414                               struct timespec *rqtp,
1415                               struct timespec __user *rmtp)
1416 {
1417         return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1418 }
1419 static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1420 {
1421         return -EINVAL;
1422 }
1423 static int thread_cpu_clock_getres(const clockid_t which_clock,
1424                                    struct timespec *tp)
1425 {
1426         return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1427 }
1428 static int thread_cpu_clock_get(const clockid_t which_clock,
1429                                 struct timespec *tp)
1430 {
1431         return posix_cpu_clock_get(THREAD_CLOCK, tp);
1432 }
1433 static int thread_cpu_timer_create(struct k_itimer *timer)
1434 {
1435         timer->it_clock = THREAD_CLOCK;
1436         return posix_cpu_timer_create(timer);
1437 }
1438 
1439 struct k_clock clock_posix_cpu = {
1440         .clock_getres   = posix_cpu_clock_getres,
1441         .clock_set      = posix_cpu_clock_set,
1442         .clock_get      = posix_cpu_clock_get,
1443         .timer_create   = posix_cpu_timer_create,
1444         .nsleep         = posix_cpu_nsleep,
1445         .nsleep_restart = posix_cpu_nsleep_restart,
1446         .timer_set      = posix_cpu_timer_set,
1447         .timer_del      = posix_cpu_timer_del,
1448         .timer_get      = posix_cpu_timer_get,
1449 };
1450 
1451 static __init int init_posix_cpu_timers(void)
1452 {
1453         struct k_clock process = {
1454                 .clock_getres   = process_cpu_clock_getres,
1455                 .clock_get      = process_cpu_clock_get,
1456                 .timer_create   = process_cpu_timer_create,
1457                 .nsleep         = process_cpu_nsleep,
1458                 .nsleep_restart = process_cpu_nsleep_restart,
1459         };
1460         struct k_clock thread = {
1461                 .clock_getres   = thread_cpu_clock_getres,
1462                 .clock_get      = thread_cpu_clock_get,
1463                 .timer_create   = thread_cpu_timer_create,
1464         };
1465         struct timespec ts;
1466 
1467         posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1468         posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1469 
1470         cputime_to_timespec(cputime_one_jiffy, &ts);
1471         onecputick = ts.tv_nsec;
1472         WARN_ON(ts.tv_sec != 0);
1473 
1474         return 0;
1475 }
1476 __initcall(init_posix_cpu_timers);
1477 

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