printk: Fix log_buf_copy termination.
[linux-2.6.git] / kernel / posix-cpu-timers.c
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
13 /*
14  * Called after updating RLIMIT_CPU to run cpu timer and update
15  * tsk->signal->cputime_expires expiration cache if necessary. Needs
16  * siglock protection since other code may update expiration cache as
17  * well.
18  */
19 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
20 {
21         cputime_t cputime = secs_to_cputime(rlim_new);
22
23         spin_lock_irq(&task->sighand->siglock);
24         set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
25         spin_unlock_irq(&task->sighand->siglock);
26 }
27
28 static int check_clock(const clockid_t which_clock)
29 {
30         int error = 0;
31         struct task_struct *p;
32         const pid_t pid = CPUCLOCK_PID(which_clock);
33
34         if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
35                 return -EINVAL;
36
37         if (pid == 0)
38                 return 0;
39
40         rcu_read_lock();
41         p = find_task_by_vpid(pid);
42         if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
43                    same_thread_group(p, current) : has_group_leader_pid(p))) {
44                 error = -EINVAL;
45         }
46         rcu_read_unlock();
47
48         return error;
49 }
50
51 static inline union cpu_time_count
52 timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
53 {
54         union cpu_time_count ret;
55         ret.sched = 0;          /* high half always zero when .cpu used */
56         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
57                 ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
58         } else {
59                 ret.cpu = timespec_to_cputime(tp);
60         }
61         return ret;
62 }
63
64 static void sample_to_timespec(const clockid_t which_clock,
65                                union cpu_time_count cpu,
66                                struct timespec *tp)
67 {
68         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED)
69                 *tp = ns_to_timespec(cpu.sched);
70         else
71                 cputime_to_timespec(cpu.cpu, tp);
72 }
73
74 static inline int cpu_time_before(const clockid_t which_clock,
75                                   union cpu_time_count now,
76                                   union cpu_time_count then)
77 {
78         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
79                 return now.sched < then.sched;
80         }  else {
81                 return cputime_lt(now.cpu, then.cpu);
82         }
83 }
84 static inline void cpu_time_add(const clockid_t which_clock,
85                                 union cpu_time_count *acc,
86                                 union cpu_time_count val)
87 {
88         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
89                 acc->sched += val.sched;
90         }  else {
91                 acc->cpu = cputime_add(acc->cpu, val.cpu);
92         }
93 }
94 static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
95                                                 union cpu_time_count a,
96                                                 union cpu_time_count b)
97 {
98         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
99                 a.sched -= b.sched;
100         }  else {
101                 a.cpu = cputime_sub(a.cpu, b.cpu);
102         }
103         return a;
104 }
105
106 /*
107  * Divide and limit the result to res >= 1
108  *
109  * This is necessary to prevent signal delivery starvation, when the result of
110  * the division would be rounded down to 0.
111  */
112 static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
113 {
114         cputime_t res = cputime_div(time, div);
115
116         return max_t(cputime_t, res, 1);
117 }
118
119 /*
120  * Update expiry time from increment, and increase overrun count,
121  * given the current clock sample.
122  */
123 static void bump_cpu_timer(struct k_itimer *timer,
124                                   union cpu_time_count now)
125 {
126         int i;
127
128         if (timer->it.cpu.incr.sched == 0)
129                 return;
130
131         if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
132                 unsigned long long delta, incr;
133
134                 if (now.sched < timer->it.cpu.expires.sched)
135                         return;
136                 incr = timer->it.cpu.incr.sched;
137                 delta = now.sched + incr - timer->it.cpu.expires.sched;
138                 /* Don't use (incr*2 < delta), incr*2 might overflow. */
139                 for (i = 0; incr < delta - incr; i++)
140                         incr = incr << 1;
141                 for (; i >= 0; incr >>= 1, i--) {
142                         if (delta < incr)
143                                 continue;
144                         timer->it.cpu.expires.sched += incr;
145                         timer->it_overrun += 1 << i;
146                         delta -= incr;
147                 }
148         } else {
149                 cputime_t delta, incr;
150
151                 if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu))
152                         return;
153                 incr = timer->it.cpu.incr.cpu;
154                 delta = cputime_sub(cputime_add(now.cpu, incr),
155                                     timer->it.cpu.expires.cpu);
156                 /* Don't use (incr*2 < delta), incr*2 might overflow. */
157                 for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
158                              incr = cputime_add(incr, incr);
159                 for (; i >= 0; incr = cputime_halve(incr), i--) {
160                         if (cputime_lt(delta, incr))
161                                 continue;
162                         timer->it.cpu.expires.cpu =
163                                 cputime_add(timer->it.cpu.expires.cpu, incr);
164                         timer->it_overrun += 1 << i;
165                         delta = cputime_sub(delta, incr);
166                 }
167         }
168 }
169
170 static inline cputime_t prof_ticks(struct task_struct *p)
171 {
172         return cputime_add(p->utime, p->stime);
173 }
174 static inline cputime_t virt_ticks(struct task_struct *p)
175 {
176         return p->utime;
177 }
178
179 static int
180 posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
181 {
182         int error = check_clock(which_clock);
183         if (!error) {
184                 tp->tv_sec = 0;
185                 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
186                 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
187                         /*
188                          * If sched_clock is using a cycle counter, we
189                          * don't have any idea of its true resolution
190                          * exported, but it is much more than 1s/HZ.
191                          */
192                         tp->tv_nsec = 1;
193                 }
194         }
195         return error;
196 }
197
198 static int
199 posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
200 {
201         /*
202          * You can never reset a CPU clock, but we check for other errors
203          * in the call before failing with EPERM.
204          */
205         int error = check_clock(which_clock);
206         if (error == 0) {
207                 error = -EPERM;
208         }
209         return error;
210 }
211
212
213 /*
214  * Sample a per-thread clock for the given task.
215  */
216 static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
217                             union cpu_time_count *cpu)
218 {
219         switch (CPUCLOCK_WHICH(which_clock)) {
220         default:
221                 return -EINVAL;
222         case CPUCLOCK_PROF:
223                 cpu->cpu = prof_ticks(p);
224                 break;
225         case CPUCLOCK_VIRT:
226                 cpu->cpu = virt_ticks(p);
227                 break;
228         case CPUCLOCK_SCHED:
229                 cpu->sched = task_sched_runtime(p);
230                 break;
231         }
232         return 0;
233 }
234
235 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
236 {
237         struct signal_struct *sig = tsk->signal;
238         struct task_struct *t;
239
240         times->utime = sig->utime;
241         times->stime = sig->stime;
242         times->sum_exec_runtime = sig->sum_sched_runtime;
243
244         rcu_read_lock();
245         /* make sure we can trust tsk->thread_group list */
246         if (!likely(pid_alive(tsk)))
247                 goto out;
248
249         t = tsk;
250         do {
251                 times->utime = cputime_add(times->utime, t->utime);
252                 times->stime = cputime_add(times->stime, t->stime);
253                 times->sum_exec_runtime += task_sched_runtime(t);
254         } while_each_thread(tsk, t);
255 out:
256         rcu_read_unlock();
257 }
258
259 static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
260 {
261         if (cputime_gt(b->utime, a->utime))
262                 a->utime = b->utime;
263
264         if (cputime_gt(b->stime, a->stime))
265                 a->stime = b->stime;
266
267         if (b->sum_exec_runtime > a->sum_exec_runtime)
268                 a->sum_exec_runtime = b->sum_exec_runtime;
269 }
270
271 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
272 {
273         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
274         struct task_cputime sum;
275         unsigned long flags;
276
277         if (!cputimer->running) {
278                 /*
279                  * The POSIX timer interface allows for absolute time expiry
280                  * values through the TIMER_ABSTIME flag, therefore we have
281                  * to synchronize the timer to the clock every time we start
282                  * it.
283                  */
284                 thread_group_cputime(tsk, &sum);
285                 spin_lock_irqsave(&cputimer->lock, flags);
286                 cputimer->running = 1;
287                 update_gt_cputime(&cputimer->cputime, &sum);
288         } else
289                 spin_lock_irqsave(&cputimer->lock, flags);
290         *times = cputimer->cputime;
291         spin_unlock_irqrestore(&cputimer->lock, flags);
292 }
293
294 /*
295  * Sample a process (thread group) clock for the given group_leader task.
296  * Must be called with tasklist_lock held for reading.
297  */
298 static int cpu_clock_sample_group(const clockid_t which_clock,
299                                   struct task_struct *p,
300                                   union cpu_time_count *cpu)
301 {
302         struct task_cputime cputime;
303
304         switch (CPUCLOCK_WHICH(which_clock)) {
305         default:
306                 return -EINVAL;
307         case CPUCLOCK_PROF:
308                 thread_group_cputime(p, &cputime);
309                 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
310                 break;
311         case CPUCLOCK_VIRT:
312                 thread_group_cputime(p, &cputime);
313                 cpu->cpu = cputime.utime;
314                 break;
315         case CPUCLOCK_SCHED:
316                 thread_group_cputime(p, &cputime);
317                 cpu->sched = cputime.sum_exec_runtime;
318                 break;
319         }
320         return 0;
321 }
322
323
324 static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
325 {
326         const pid_t pid = CPUCLOCK_PID(which_clock);
327         int error = -EINVAL;
328         union cpu_time_count rtn;
329
330         if (pid == 0) {
331                 /*
332                  * Special case constant value for our own clocks.
333                  * We don't have to do any lookup to find ourselves.
334                  */
335                 if (CPUCLOCK_PERTHREAD(which_clock)) {
336                         /*
337                          * Sampling just ourselves we can do with no locking.
338                          */
339                         error = cpu_clock_sample(which_clock,
340                                                  current, &rtn);
341                 } else {
342                         read_lock(&tasklist_lock);
343                         error = cpu_clock_sample_group(which_clock,
344                                                        current, &rtn);
345                         read_unlock(&tasklist_lock);
346                 }
347         } else {
348                 /*
349                  * Find the given PID, and validate that the caller
350                  * should be able to see it.
351                  */
352                 struct task_struct *p;
353                 rcu_read_lock();
354                 p = find_task_by_vpid(pid);
355                 if (p) {
356                         if (CPUCLOCK_PERTHREAD(which_clock)) {
357                                 if (same_thread_group(p, current)) {
358                                         error = cpu_clock_sample(which_clock,
359                                                                  p, &rtn);
360                                 }
361                         } else {
362                                 read_lock(&tasklist_lock);
363                                 if (thread_group_leader(p) && p->sighand) {
364                                         error =
365                                             cpu_clock_sample_group(which_clock,
366                                                                    p, &rtn);
367                                 }
368                                 read_unlock(&tasklist_lock);
369                         }
370                 }
371                 rcu_read_unlock();
372         }
373
374         if (error)
375                 return error;
376         sample_to_timespec(which_clock, rtn, tp);
377         return 0;
378 }
379
380
381 /*
382  * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
383  * This is called from sys_timer_create() and do_cpu_nanosleep() with the
384  * new timer already all-zeros initialized.
385  */
386 static int posix_cpu_timer_create(struct k_itimer *new_timer)
387 {
388         int ret = 0;
389         const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
390         struct task_struct *p;
391
392         if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
393                 return -EINVAL;
394
395         INIT_LIST_HEAD(&new_timer->it.cpu.entry);
396
397         rcu_read_lock();
398         if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
399                 if (pid == 0) {
400                         p = current;
401                 } else {
402                         p = find_task_by_vpid(pid);
403                         if (p && !same_thread_group(p, current))
404                                 p = NULL;
405                 }
406         } else {
407                 if (pid == 0) {
408                         p = current->group_leader;
409                 } else {
410                         p = find_task_by_vpid(pid);
411                         if (p && !has_group_leader_pid(p))
412                                 p = NULL;
413                 }
414         }
415         new_timer->it.cpu.task = p;
416         if (p) {
417                 get_task_struct(p);
418         } else {
419                 ret = -EINVAL;
420         }
421         rcu_read_unlock();
422
423         return ret;
424 }
425
426 /*
427  * Clean up a CPU-clock timer that is about to be destroyed.
428  * This is called from timer deletion with the timer already locked.
429  * If we return TIMER_RETRY, it's necessary to release the timer's lock
430  * and try again.  (This happens when the timer is in the middle of firing.)
431  */
432 static int posix_cpu_timer_del(struct k_itimer *timer)
433 {
434         struct task_struct *p = timer->it.cpu.task;
435         int ret = 0;
436
437         if (likely(p != NULL)) {
438                 read_lock(&tasklist_lock);
439                 if (unlikely(p->sighand == NULL)) {
440                         /*
441                          * We raced with the reaping of the task.
442                          * The deletion should have cleared us off the list.
443                          */
444                         BUG_ON(!list_empty(&timer->it.cpu.entry));
445                 } else {
446                         spin_lock(&p->sighand->siglock);
447                         if (timer->it.cpu.firing)
448                                 ret = TIMER_RETRY;
449                         else
450                                 list_del(&timer->it.cpu.entry);
451                         spin_unlock(&p->sighand->siglock);
452                 }
453                 read_unlock(&tasklist_lock);
454
455                 if (!ret)
456                         put_task_struct(p);
457         }
458
459         return ret;
460 }
461
462 /*
463  * Clean out CPU timers still ticking when a thread exited.  The task
464  * pointer is cleared, and the expiry time is replaced with the residual
465  * time for later timer_gettime calls to return.
466  * This must be called with the siglock held.
467  */
468 static void cleanup_timers(struct list_head *head,
469                            cputime_t utime, cputime_t stime,
470                            unsigned long long sum_exec_runtime)
471 {
472         struct cpu_timer_list *timer, *next;
473         cputime_t ptime = cputime_add(utime, stime);
474
475         list_for_each_entry_safe(timer, next, head, entry) {
476                 list_del_init(&timer->entry);
477                 if (cputime_lt(timer->expires.cpu, ptime)) {
478                         timer->expires.cpu = cputime_zero;
479                 } else {
480                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
481                                                          ptime);
482                 }
483         }
484
485         ++head;
486         list_for_each_entry_safe(timer, next, head, entry) {
487                 list_del_init(&timer->entry);
488                 if (cputime_lt(timer->expires.cpu, utime)) {
489                         timer->expires.cpu = cputime_zero;
490                 } else {
491                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
492                                                          utime);
493                 }
494         }
495
496         ++head;
497         list_for_each_entry_safe(timer, next, head, entry) {
498                 list_del_init(&timer->entry);
499                 if (timer->expires.sched < sum_exec_runtime) {
500                         timer->expires.sched = 0;
501                 } else {
502                         timer->expires.sched -= sum_exec_runtime;
503                 }
504         }
505 }
506
507 /*
508  * These are both called with the siglock held, when the current thread
509  * is being reaped.  When the final (leader) thread in the group is reaped,
510  * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
511  */
512 void posix_cpu_timers_exit(struct task_struct *tsk)
513 {
514         cleanup_timers(tsk->cpu_timers,
515                        tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
516
517 }
518 void posix_cpu_timers_exit_group(struct task_struct *tsk)
519 {
520         struct signal_struct *const sig = tsk->signal;
521
522         cleanup_timers(tsk->signal->cpu_timers,
523                        cputime_add(tsk->utime, sig->utime),
524                        cputime_add(tsk->stime, sig->stime),
525                        tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
526 }
527
528 static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
529 {
530         /*
531          * That's all for this thread or process.
532          * We leave our residual in expires to be reported.
533          */
534         put_task_struct(timer->it.cpu.task);
535         timer->it.cpu.task = NULL;
536         timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
537                                              timer->it.cpu.expires,
538                                              now);
539 }
540
541 static inline int expires_gt(cputime_t expires, cputime_t new_exp)
542 {
543         return cputime_eq(expires, cputime_zero) ||
544                cputime_gt(expires, new_exp);
545 }
546
547 /*
548  * Insert the timer on the appropriate list before any timers that
549  * expire later.  This must be called with the tasklist_lock held
550  * for reading, interrupts disabled and p->sighand->siglock taken.
551  */
552 static void arm_timer(struct k_itimer *timer)
553 {
554         struct task_struct *p = timer->it.cpu.task;
555         struct list_head *head, *listpos;
556         struct task_cputime *cputime_expires;
557         struct cpu_timer_list *const nt = &timer->it.cpu;
558         struct cpu_timer_list *next;
559
560         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
561                 head = p->cpu_timers;
562                 cputime_expires = &p->cputime_expires;
563         } else {
564                 head = p->signal->cpu_timers;
565                 cputime_expires = &p->signal->cputime_expires;
566         }
567         head += CPUCLOCK_WHICH(timer->it_clock);
568
569         listpos = head;
570         list_for_each_entry(next, head, entry) {
571                 if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
572                         break;
573                 listpos = &next->entry;
574         }
575         list_add(&nt->entry, listpos);
576
577         if (listpos == head) {
578                 union cpu_time_count *exp = &nt->expires;
579
580                 /*
581                  * We are the new earliest-expiring POSIX 1.b timer, hence
582                  * need to update expiration cache. Take into account that
583                  * for process timers we share expiration cache with itimers
584                  * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
585                  */
586
587                 switch (CPUCLOCK_WHICH(timer->it_clock)) {
588                 case CPUCLOCK_PROF:
589                         if (expires_gt(cputime_expires->prof_exp, exp->cpu))
590                                 cputime_expires->prof_exp = exp->cpu;
591                         break;
592                 case CPUCLOCK_VIRT:
593                         if (expires_gt(cputime_expires->virt_exp, exp->cpu))
594                                 cputime_expires->virt_exp = exp->cpu;
595                         break;
596                 case CPUCLOCK_SCHED:
597                         if (cputime_expires->sched_exp == 0 ||
598                             cputime_expires->sched_exp > exp->sched)
599                                 cputime_expires->sched_exp = exp->sched;
600                         break;
601                 }
602         }
603 }
604
605 /*
606  * The timer is locked, fire it and arrange for its reload.
607  */
608 static void cpu_timer_fire(struct k_itimer *timer)
609 {
610         if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
611                 /*
612                  * User don't want any signal.
613                  */
614                 timer->it.cpu.expires.sched = 0;
615         } else if (unlikely(timer->sigq == NULL)) {
616                 /*
617                  * This a special case for clock_nanosleep,
618                  * not a normal timer from sys_timer_create.
619                  */
620                 wake_up_process(timer->it_process);
621                 timer->it.cpu.expires.sched = 0;
622         } else if (timer->it.cpu.incr.sched == 0) {
623                 /*
624                  * One-shot timer.  Clear it as soon as it's fired.
625                  */
626                 posix_timer_event(timer, 0);
627                 timer->it.cpu.expires.sched = 0;
628         } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
629                 /*
630                  * The signal did not get queued because the signal
631                  * was ignored, so we won't get any callback to
632                  * reload the timer.  But we need to keep it
633                  * ticking in case the signal is deliverable next time.
634                  */
635                 posix_cpu_timer_schedule(timer);
636         }
637 }
638
639 /*
640  * Sample a process (thread group) timer for the given group_leader task.
641  * Must be called with tasklist_lock held for reading.
642  */
643 static int cpu_timer_sample_group(const clockid_t which_clock,
644                                   struct task_struct *p,
645                                   union cpu_time_count *cpu)
646 {
647         struct task_cputime cputime;
648
649         thread_group_cputimer(p, &cputime);
650         switch (CPUCLOCK_WHICH(which_clock)) {
651         default:
652                 return -EINVAL;
653         case CPUCLOCK_PROF:
654                 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
655                 break;
656         case CPUCLOCK_VIRT:
657                 cpu->cpu = cputime.utime;
658                 break;
659         case CPUCLOCK_SCHED:
660                 cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
661                 break;
662         }
663         return 0;
664 }
665
666 /*
667  * Guts of sys_timer_settime for CPU timers.
668  * This is called with the timer locked and interrupts disabled.
669  * If we return TIMER_RETRY, it's necessary to release the timer's lock
670  * and try again.  (This happens when the timer is in the middle of firing.)
671  */
672 static int posix_cpu_timer_set(struct k_itimer *timer, int flags,
673                                struct itimerspec *new, struct itimerspec *old)
674 {
675         struct task_struct *p = timer->it.cpu.task;
676         union cpu_time_count old_expires, new_expires, old_incr, val;
677         int ret;
678
679         if (unlikely(p == NULL)) {
680                 /*
681                  * Timer refers to a dead task's clock.
682                  */
683                 return -ESRCH;
684         }
685
686         new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
687
688         read_lock(&tasklist_lock);
689         /*
690          * We need the tasklist_lock to protect against reaping that
691          * clears p->sighand.  If p has just been reaped, we can no
692          * longer get any information about it at all.
693          */
694         if (unlikely(p->sighand == NULL)) {
695                 read_unlock(&tasklist_lock);
696                 put_task_struct(p);
697                 timer->it.cpu.task = NULL;
698                 return -ESRCH;
699         }
700
701         /*
702          * Disarm any old timer after extracting its expiry time.
703          */
704         BUG_ON(!irqs_disabled());
705
706         ret = 0;
707         old_incr = timer->it.cpu.incr;
708         spin_lock(&p->sighand->siglock);
709         old_expires = timer->it.cpu.expires;
710         if (unlikely(timer->it.cpu.firing)) {
711                 timer->it.cpu.firing = -1;
712                 ret = TIMER_RETRY;
713         } else
714                 list_del_init(&timer->it.cpu.entry);
715
716         /*
717          * We need to sample the current value to convert the new
718          * value from to relative and absolute, and to convert the
719          * old value from absolute to relative.  To set a process
720          * timer, we need a sample to balance the thread expiry
721          * times (in arm_timer).  With an absolute time, we must
722          * check if it's already passed.  In short, we need a sample.
723          */
724         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
725                 cpu_clock_sample(timer->it_clock, p, &val);
726         } else {
727                 cpu_timer_sample_group(timer->it_clock, p, &val);
728         }
729
730         if (old) {
731                 if (old_expires.sched == 0) {
732                         old->it_value.tv_sec = 0;
733                         old->it_value.tv_nsec = 0;
734                 } else {
735                         /*
736                          * Update the timer in case it has
737                          * overrun already.  If it has,
738                          * we'll report it as having overrun
739                          * and with the next reloaded timer
740                          * already ticking, though we are
741                          * swallowing that pending
742                          * notification here to install the
743                          * new setting.
744                          */
745                         bump_cpu_timer(timer, val);
746                         if (cpu_time_before(timer->it_clock, val,
747                                             timer->it.cpu.expires)) {
748                                 old_expires = cpu_time_sub(
749                                         timer->it_clock,
750                                         timer->it.cpu.expires, val);
751                                 sample_to_timespec(timer->it_clock,
752                                                    old_expires,
753                                                    &old->it_value);
754                         } else {
755                                 old->it_value.tv_nsec = 1;
756                                 old->it_value.tv_sec = 0;
757                         }
758                 }
759         }
760
761         if (unlikely(ret)) {
762                 /*
763                  * We are colliding with the timer actually firing.
764                  * Punt after filling in the timer's old value, and
765                  * disable this firing since we are already reporting
766                  * it as an overrun (thanks to bump_cpu_timer above).
767                  */
768                 spin_unlock(&p->sighand->siglock);
769                 read_unlock(&tasklist_lock);
770                 goto out;
771         }
772
773         if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
774                 cpu_time_add(timer->it_clock, &new_expires, val);
775         }
776
777         /*
778          * Install the new expiry time (or zero).
779          * For a timer with no notification action, we don't actually
780          * arm the timer (we'll just fake it for timer_gettime).
781          */
782         timer->it.cpu.expires = new_expires;
783         if (new_expires.sched != 0 &&
784             cpu_time_before(timer->it_clock, val, new_expires)) {
785                 arm_timer(timer);
786         }
787
788         spin_unlock(&p->sighand->siglock);
789         read_unlock(&tasklist_lock);
790
791         /*
792          * Install the new reload setting, and
793          * set up the signal and overrun bookkeeping.
794          */
795         timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
796                                                 &new->it_interval);
797
798         /*
799          * This acts as a modification timestamp for the timer,
800          * so any automatic reload attempt will punt on seeing
801          * that we have reset the timer manually.
802          */
803         timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
804                 ~REQUEUE_PENDING;
805         timer->it_overrun_last = 0;
806         timer->it_overrun = -1;
807
808         if (new_expires.sched != 0 &&
809             !cpu_time_before(timer->it_clock, val, new_expires)) {
810                 /*
811                  * The designated time already passed, so we notify
812                  * immediately, even if the thread never runs to
813                  * accumulate more time on this clock.
814                  */
815                 cpu_timer_fire(timer);
816         }
817
818         ret = 0;
819  out:
820         if (old) {
821                 sample_to_timespec(timer->it_clock,
822                                    old_incr, &old->it_interval);
823         }
824         return ret;
825 }
826
827 static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
828 {
829         union cpu_time_count now;
830         struct task_struct *p = timer->it.cpu.task;
831         int clear_dead;
832
833         /*
834          * Easy part: convert the reload time.
835          */
836         sample_to_timespec(timer->it_clock,
837                            timer->it.cpu.incr, &itp->it_interval);
838
839         if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all.  */
840                 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
841                 return;
842         }
843
844         if (unlikely(p == NULL)) {
845                 /*
846                  * This task already died and the timer will never fire.
847                  * In this case, expires is actually the dead value.
848                  */
849         dead:
850                 sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
851                                    &itp->it_value);
852                 return;
853         }
854
855         /*
856          * Sample the clock to take the difference with the expiry time.
857          */
858         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
859                 cpu_clock_sample(timer->it_clock, p, &now);
860                 clear_dead = p->exit_state;
861         } else {
862                 read_lock(&tasklist_lock);
863                 if (unlikely(p->sighand == NULL)) {
864                         /*
865                          * The process has been reaped.
866                          * We can't even collect a sample any more.
867                          * Call the timer disarmed, nothing else to do.
868                          */
869                         put_task_struct(p);
870                         timer->it.cpu.task = NULL;
871                         timer->it.cpu.expires.sched = 0;
872                         read_unlock(&tasklist_lock);
873                         goto dead;
874                 } else {
875                         cpu_timer_sample_group(timer->it_clock, p, &now);
876                         clear_dead = (unlikely(p->exit_state) &&
877                                       thread_group_empty(p));
878                 }
879                 read_unlock(&tasklist_lock);
880         }
881
882         if (unlikely(clear_dead)) {
883                 /*
884                  * We've noticed that the thread is dead, but
885                  * not yet reaped.  Take this opportunity to
886                  * drop our task ref.
887                  */
888                 clear_dead_task(timer, now);
889                 goto dead;
890         }
891
892         if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
893                 sample_to_timespec(timer->it_clock,
894                                    cpu_time_sub(timer->it_clock,
895                                                 timer->it.cpu.expires, now),
896                                    &itp->it_value);
897         } else {
898                 /*
899                  * The timer should have expired already, but the firing
900                  * hasn't taken place yet.  Say it's just about to expire.
901                  */
902                 itp->it_value.tv_nsec = 1;
903                 itp->it_value.tv_sec = 0;
904         }
905 }
906
907 /*
908  * Check for any per-thread CPU timers that have fired and move them off
909  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
910  * tsk->it_*_expires values to reflect the remaining thread CPU timers.
911  */
912 static void check_thread_timers(struct task_struct *tsk,
913                                 struct list_head *firing)
914 {
915         int maxfire;
916         struct list_head *timers = tsk->cpu_timers;
917         struct signal_struct *const sig = tsk->signal;
918         unsigned long soft;
919
920         maxfire = 20;
921         tsk->cputime_expires.prof_exp = cputime_zero;
922         while (!list_empty(timers)) {
923                 struct cpu_timer_list *t = list_first_entry(timers,
924                                                       struct cpu_timer_list,
925                                                       entry);
926                 if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
927                         tsk->cputime_expires.prof_exp = t->expires.cpu;
928                         break;
929                 }
930                 t->firing = 1;
931                 list_move_tail(&t->entry, firing);
932         }
933
934         ++timers;
935         maxfire = 20;
936         tsk->cputime_expires.virt_exp = cputime_zero;
937         while (!list_empty(timers)) {
938                 struct cpu_timer_list *t = list_first_entry(timers,
939                                                       struct cpu_timer_list,
940                                                       entry);
941                 if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
942                         tsk->cputime_expires.virt_exp = t->expires.cpu;
943                         break;
944                 }
945                 t->firing = 1;
946                 list_move_tail(&t->entry, firing);
947         }
948
949         ++timers;
950         maxfire = 20;
951         tsk->cputime_expires.sched_exp = 0;
952         while (!list_empty(timers)) {
953                 struct cpu_timer_list *t = list_first_entry(timers,
954                                                       struct cpu_timer_list,
955                                                       entry);
956                 if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
957                         tsk->cputime_expires.sched_exp = t->expires.sched;
958                         break;
959                 }
960                 t->firing = 1;
961                 list_move_tail(&t->entry, firing);
962         }
963
964         /*
965          * Check for the special case thread timers.
966          */
967         soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
968         if (soft != RLIM_INFINITY) {
969                 unsigned long hard =
970                         ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
971
972                 if (hard != RLIM_INFINITY &&
973                     tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
974                         /*
975                          * At the hard limit, we just die.
976                          * No need to calculate anything else now.
977                          */
978                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
979                         return;
980                 }
981                 if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
982                         /*
983                          * At the soft limit, send a SIGXCPU every second.
984                          */
985                         if (soft < hard) {
986                                 soft += USEC_PER_SEC;
987                                 sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
988                         }
989                         printk(KERN_INFO
990                                 "RT Watchdog Timeout: %s[%d]\n",
991                                 tsk->comm, task_pid_nr(tsk));
992                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
993                 }
994         }
995 }
996
997 static void stop_process_timers(struct signal_struct *sig)
998 {
999         struct thread_group_cputimer *cputimer = &sig->cputimer;
1000         unsigned long flags;
1001
1002         spin_lock_irqsave(&cputimer->lock, flags);
1003         cputimer->running = 0;
1004         spin_unlock_irqrestore(&cputimer->lock, flags);
1005 }
1006
1007 static u32 onecputick;
1008
1009 static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
1010                              cputime_t *expires, cputime_t cur_time, int signo)
1011 {
1012         if (cputime_eq(it->expires, cputime_zero))
1013                 return;
1014
1015         if (cputime_ge(cur_time, it->expires)) {
1016                 if (!cputime_eq(it->incr, cputime_zero)) {
1017                         it->expires = cputime_add(it->expires, it->incr);
1018                         it->error += it->incr_error;
1019                         if (it->error >= onecputick) {
1020                                 it->expires = cputime_sub(it->expires,
1021                                                           cputime_one_jiffy);
1022                                 it->error -= onecputick;
1023                         }
1024                 } else {
1025                         it->expires = cputime_zero;
1026                 }
1027
1028                 trace_itimer_expire(signo == SIGPROF ?
1029                                     ITIMER_PROF : ITIMER_VIRTUAL,
1030                                     tsk->signal->leader_pid, cur_time);
1031                 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
1032         }
1033
1034         if (!cputime_eq(it->expires, cputime_zero) &&
1035             (cputime_eq(*expires, cputime_zero) ||
1036              cputime_lt(it->expires, *expires))) {
1037                 *expires = it->expires;
1038         }
1039 }
1040
1041 /**
1042  * task_cputime_zero - Check a task_cputime struct for all zero fields.
1043  *
1044  * @cputime:    The struct to compare.
1045  *
1046  * Checks @cputime to see if all fields are zero.  Returns true if all fields
1047  * are zero, false if any field is nonzero.
1048  */
1049 static inline int task_cputime_zero(const struct task_cputime *cputime)
1050 {
1051         if (cputime_eq(cputime->utime, cputime_zero) &&
1052             cputime_eq(cputime->stime, cputime_zero) &&
1053             cputime->sum_exec_runtime == 0)
1054                 return 1;
1055         return 0;
1056 }
1057
1058 /*
1059  * Check for any per-thread CPU timers that have fired and move them
1060  * off the tsk->*_timers list onto the firing list.  Per-thread timers
1061  * have already been taken off.
1062  */
1063 static void check_process_timers(struct task_struct *tsk,
1064                                  struct list_head *firing)
1065 {
1066         int maxfire;
1067         struct signal_struct *const sig = tsk->signal;
1068         cputime_t utime, ptime, virt_expires, prof_expires;
1069         unsigned long long sum_sched_runtime, sched_expires;
1070         struct list_head *timers = sig->cpu_timers;
1071         struct task_cputime cputime;
1072         unsigned long soft;
1073
1074         /*
1075          * Collect the current process totals.
1076          */
1077         thread_group_cputimer(tsk, &cputime);
1078         utime = cputime.utime;
1079         ptime = cputime_add(utime, cputime.stime);
1080         sum_sched_runtime = cputime.sum_exec_runtime;
1081         maxfire = 20;
1082         prof_expires = cputime_zero;
1083         while (!list_empty(timers)) {
1084                 struct cpu_timer_list *tl = list_first_entry(timers,
1085                                                       struct cpu_timer_list,
1086                                                       entry);
1087                 if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) {
1088                         prof_expires = tl->expires.cpu;
1089                         break;
1090                 }
1091                 tl->firing = 1;
1092                 list_move_tail(&tl->entry, firing);
1093         }
1094
1095         ++timers;
1096         maxfire = 20;
1097         virt_expires = cputime_zero;
1098         while (!list_empty(timers)) {
1099                 struct cpu_timer_list *tl = list_first_entry(timers,
1100                                                       struct cpu_timer_list,
1101                                                       entry);
1102                 if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) {
1103                         virt_expires = tl->expires.cpu;
1104                         break;
1105                 }
1106                 tl->firing = 1;
1107                 list_move_tail(&tl->entry, firing);
1108         }
1109
1110         ++timers;
1111         maxfire = 20;
1112         sched_expires = 0;
1113         while (!list_empty(timers)) {
1114                 struct cpu_timer_list *tl = list_first_entry(timers,
1115                                                       struct cpu_timer_list,
1116                                                       entry);
1117                 if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1118                         sched_expires = tl->expires.sched;
1119                         break;
1120                 }
1121                 tl->firing = 1;
1122                 list_move_tail(&tl->entry, firing);
1123         }
1124
1125         /*
1126          * Check for the special case process timers.
1127          */
1128         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1129                          SIGPROF);
1130         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1131                          SIGVTALRM);
1132         soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1133         if (soft != RLIM_INFINITY) {
1134                 unsigned long psecs = cputime_to_secs(ptime);
1135                 unsigned long hard =
1136                         ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
1137                 cputime_t x;
1138                 if (psecs >= hard) {
1139                         /*
1140                          * At the hard limit, we just die.
1141                          * No need to calculate anything else now.
1142                          */
1143                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1144                         return;
1145                 }
1146                 if (psecs >= soft) {
1147                         /*
1148                          * At the soft limit, send a SIGXCPU every second.
1149                          */
1150                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1151                         if (soft < hard) {
1152                                 soft++;
1153                                 sig->rlim[RLIMIT_CPU].rlim_cur = soft;
1154                         }
1155                 }
1156                 x = secs_to_cputime(soft);
1157                 if (cputime_eq(prof_expires, cputime_zero) ||
1158                     cputime_lt(x, prof_expires)) {
1159                         prof_expires = x;
1160                 }
1161         }
1162
1163         sig->cputime_expires.prof_exp = prof_expires;
1164         sig->cputime_expires.virt_exp = virt_expires;
1165         sig->cputime_expires.sched_exp = sched_expires;
1166         if (task_cputime_zero(&sig->cputime_expires))
1167                 stop_process_timers(sig);
1168 }
1169
1170 /*
1171  * This is called from the signal code (via do_schedule_next_timer)
1172  * when the last timer signal was delivered and we have to reload the timer.
1173  */
1174 void posix_cpu_timer_schedule(struct k_itimer *timer)
1175 {
1176         struct task_struct *p = timer->it.cpu.task;
1177         union cpu_time_count now;
1178
1179         if (unlikely(p == NULL))
1180                 /*
1181                  * The task was cleaned up already, no future firings.
1182                  */
1183                 goto out;
1184
1185         /*
1186          * Fetch the current sample and update the timer's expiry time.
1187          */
1188         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1189                 cpu_clock_sample(timer->it_clock, p, &now);
1190                 bump_cpu_timer(timer, now);
1191                 if (unlikely(p->exit_state)) {
1192                         clear_dead_task(timer, now);
1193                         goto out;
1194                 }
1195                 read_lock(&tasklist_lock); /* arm_timer needs it.  */
1196                 spin_lock(&p->sighand->siglock);
1197         } else {
1198                 read_lock(&tasklist_lock);
1199                 if (unlikely(p->sighand == NULL)) {
1200                         /*
1201                          * The process has been reaped.
1202                          * We can't even collect a sample any more.
1203                          */
1204                         put_task_struct(p);
1205                         timer->it.cpu.task = p = NULL;
1206                         timer->it.cpu.expires.sched = 0;
1207                         goto out_unlock;
1208                 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1209                         /*
1210                          * We've noticed that the thread is dead, but
1211                          * not yet reaped.  Take this opportunity to
1212                          * drop our task ref.
1213                          */
1214                         clear_dead_task(timer, now);
1215                         goto out_unlock;
1216                 }
1217                 spin_lock(&p->sighand->siglock);
1218                 cpu_timer_sample_group(timer->it_clock, p, &now);
1219                 bump_cpu_timer(timer, now);
1220                 /* Leave the tasklist_lock locked for the call below.  */
1221         }
1222
1223         /*
1224          * Now re-arm for the new expiry time.
1225          */
1226         BUG_ON(!irqs_disabled());
1227         arm_timer(timer);
1228         spin_unlock(&p->sighand->siglock);
1229
1230 out_unlock:
1231         read_unlock(&tasklist_lock);
1232
1233 out:
1234         timer->it_overrun_last = timer->it_overrun;
1235         timer->it_overrun = -1;
1236         ++timer->it_requeue_pending;
1237 }
1238
1239 /**
1240  * task_cputime_expired - Compare two task_cputime entities.
1241  *
1242  * @sample:     The task_cputime structure to be checked for expiration.
1243  * @expires:    Expiration times, against which @sample will be checked.
1244  *
1245  * Checks @sample against @expires to see if any field of @sample has expired.
1246  * Returns true if any field of the former is greater than the corresponding
1247  * field of the latter if the latter field is set.  Otherwise returns false.
1248  */
1249 static inline int task_cputime_expired(const struct task_cputime *sample,
1250                                         const struct task_cputime *expires)
1251 {
1252         if (!cputime_eq(expires->utime, cputime_zero) &&
1253             cputime_ge(sample->utime, expires->utime))
1254                 return 1;
1255         if (!cputime_eq(expires->stime, cputime_zero) &&
1256             cputime_ge(cputime_add(sample->utime, sample->stime),
1257                        expires->stime))
1258                 return 1;
1259         if (expires->sum_exec_runtime != 0 &&
1260             sample->sum_exec_runtime >= expires->sum_exec_runtime)
1261                 return 1;
1262         return 0;
1263 }
1264
1265 /**
1266  * fastpath_timer_check - POSIX CPU timers fast path.
1267  *
1268  * @tsk:        The task (thread) being checked.
1269  *
1270  * Check the task and thread group timers.  If both are zero (there are no
1271  * timers set) return false.  Otherwise snapshot the task and thread group
1272  * timers and compare them with the corresponding expiration times.  Return
1273  * true if a timer has expired, else return false.
1274  */
1275 static inline int fastpath_timer_check(struct task_struct *tsk)
1276 {
1277         struct signal_struct *sig;
1278
1279         if (!task_cputime_zero(&tsk->cputime_expires)) {
1280                 struct task_cputime task_sample = {
1281                         .utime = tsk->utime,
1282                         .stime = tsk->stime,
1283                         .sum_exec_runtime = tsk->se.sum_exec_runtime
1284                 };
1285
1286                 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1287                         return 1;
1288         }
1289
1290         sig = tsk->signal;
1291         if (sig->cputimer.running) {
1292                 struct task_cputime group_sample;
1293
1294                 spin_lock(&sig->cputimer.lock);
1295                 group_sample = sig->cputimer.cputime;
1296                 spin_unlock(&sig->cputimer.lock);
1297
1298                 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1299                         return 1;
1300         }
1301
1302         return 0;
1303 }
1304
1305 /*
1306  * This is called from the timer interrupt handler.  The irq handler has
1307  * already updated our counts.  We need to check if any timers fire now.
1308  * Interrupts are disabled.
1309  */
1310 void run_posix_cpu_timers(struct task_struct *tsk)
1311 {
1312         LIST_HEAD(firing);
1313         struct k_itimer *timer, *next;
1314         unsigned long flags;
1315
1316         BUG_ON(!irqs_disabled());
1317
1318         /*
1319          * The fast path checks that there are no expired thread or thread
1320          * group timers.  If that's so, just return.
1321          */
1322         if (!fastpath_timer_check(tsk))
1323                 return;
1324
1325         if (!lock_task_sighand(tsk, &flags))
1326                 return;
1327         /*
1328          * Here we take off tsk->signal->cpu_timers[N] and
1329          * tsk->cpu_timers[N] all the timers that are firing, and
1330          * put them on the firing list.
1331          */
1332         check_thread_timers(tsk, &firing);
1333         /*
1334          * If there are any active process wide timers (POSIX 1.b, itimers,
1335          * RLIMIT_CPU) cputimer must be running.
1336          */
1337         if (tsk->signal->cputimer.running)
1338                 check_process_timers(tsk, &firing);
1339
1340         /*
1341          * We must release these locks before taking any timer's lock.
1342          * There is a potential race with timer deletion here, as the
1343          * siglock now protects our private firing list.  We have set
1344          * the firing flag in each timer, so that a deletion attempt
1345          * that gets the timer lock before we do will give it up and
1346          * spin until we've taken care of that timer below.
1347          */
1348         unlock_task_sighand(tsk, &flags);
1349
1350         /*
1351          * Now that all the timers on our list have the firing flag,
1352          * no one will touch their list entries but us.  We'll take
1353          * each timer's lock before clearing its firing flag, so no
1354          * timer call will interfere.
1355          */
1356         list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1357                 int cpu_firing;
1358
1359                 spin_lock(&timer->it_lock);
1360                 list_del_init(&timer->it.cpu.entry);
1361                 cpu_firing = timer->it.cpu.firing;
1362                 timer->it.cpu.firing = 0;
1363                 /*
1364                  * The firing flag is -1 if we collided with a reset
1365                  * of the timer, which already reported this
1366                  * almost-firing as an overrun.  So don't generate an event.
1367                  */
1368                 if (likely(cpu_firing >= 0))
1369                         cpu_timer_fire(timer);
1370                 spin_unlock(&timer->it_lock);
1371         }
1372 }
1373
1374 /*
1375  * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1376  * The tsk->sighand->siglock must be held by the caller.
1377  */
1378 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1379                            cputime_t *newval, cputime_t *oldval)
1380 {
1381         union cpu_time_count now;
1382
1383         BUG_ON(clock_idx == CPUCLOCK_SCHED);
1384         cpu_timer_sample_group(clock_idx, tsk, &now);
1385
1386         if (oldval) {
1387                 /*
1388                  * We are setting itimer. The *oldval is absolute and we update
1389                  * it to be relative, *newval argument is relative and we update
1390                  * it to be absolute.
1391                  */
1392                 if (!cputime_eq(*oldval, cputime_zero)) {
1393                         if (cputime_le(*oldval, now.cpu)) {
1394                                 /* Just about to fire. */
1395                                 *oldval = cputime_one_jiffy;
1396                         } else {
1397                                 *oldval = cputime_sub(*oldval, now.cpu);
1398                         }
1399                 }
1400
1401                 if (cputime_eq(*newval, cputime_zero))
1402                         return;
1403                 *newval = cputime_add(*newval, now.cpu);
1404         }
1405
1406         /*
1407          * Update expiration cache if we are the earliest timer, or eventually
1408          * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1409          */
1410         switch (clock_idx) {
1411         case CPUCLOCK_PROF:
1412                 if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1413                         tsk->signal->cputime_expires.prof_exp = *newval;
1414                 break;
1415         case CPUCLOCK_VIRT:
1416                 if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1417                         tsk->signal->cputime_expires.virt_exp = *newval;
1418                 break;
1419         }
1420 }
1421
1422 static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1423                             struct timespec *rqtp, struct itimerspec *it)
1424 {
1425         struct k_itimer timer;
1426         int error;
1427
1428         /*
1429          * Set up a temporary timer and then wait for it to go off.
1430          */
1431         memset(&timer, 0, sizeof timer);
1432         spin_lock_init(&timer.it_lock);
1433         timer.it_clock = which_clock;
1434         timer.it_overrun = -1;
1435         error = posix_cpu_timer_create(&timer);
1436         timer.it_process = current;
1437         if (!error) {
1438                 static struct itimerspec zero_it;
1439
1440                 memset(it, 0, sizeof *it);
1441                 it->it_value = *rqtp;
1442
1443                 spin_lock_irq(&timer.it_lock);
1444                 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1445                 if (error) {
1446                         spin_unlock_irq(&timer.it_lock);
1447                         return error;
1448                 }
1449
1450                 while (!signal_pending(current)) {
1451                         if (timer.it.cpu.expires.sched == 0) {
1452                                 /*
1453                                  * Our timer fired and was reset.
1454                                  */
1455                                 spin_unlock_irq(&timer.it_lock);
1456                                 return 0;
1457                         }
1458
1459                         /*
1460                          * Block until cpu_timer_fire (or a signal) wakes us.
1461                          */
1462                         __set_current_state(TASK_INTERRUPTIBLE);
1463                         spin_unlock_irq(&timer.it_lock);
1464                         schedule();
1465                         spin_lock_irq(&timer.it_lock);
1466                 }
1467
1468                 /*
1469                  * We were interrupted by a signal.
1470                  */
1471                 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1472                 posix_cpu_timer_set(&timer, 0, &zero_it, it);
1473                 spin_unlock_irq(&timer.it_lock);
1474
1475                 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1476                         /*
1477                          * It actually did fire already.
1478                          */
1479                         return 0;
1480                 }
1481
1482                 error = -ERESTART_RESTARTBLOCK;
1483         }
1484
1485         return error;
1486 }
1487
1488 static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1489
1490 static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1491                             struct timespec *rqtp, struct timespec __user *rmtp)
1492 {
1493         struct restart_block *restart_block =
1494                 &current_thread_info()->restart_block;
1495         struct itimerspec it;
1496         int error;
1497
1498         /*
1499          * Diagnose required errors first.
1500          */
1501         if (CPUCLOCK_PERTHREAD(which_clock) &&
1502             (CPUCLOCK_PID(which_clock) == 0 ||
1503              CPUCLOCK_PID(which_clock) == current->pid))
1504                 return -EINVAL;
1505
1506         error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1507
1508         if (error == -ERESTART_RESTARTBLOCK) {
1509
1510                 if (flags & TIMER_ABSTIME)
1511                         return -ERESTARTNOHAND;
1512                 /*
1513                  * Report back to the user the time still remaining.
1514                  */
1515                 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1516                         return -EFAULT;
1517
1518                 restart_block->fn = posix_cpu_nsleep_restart;
1519                 restart_block->nanosleep.clockid = which_clock;
1520                 restart_block->nanosleep.rmtp = rmtp;
1521                 restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1522         }
1523         return error;
1524 }
1525
1526 static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1527 {
1528         clockid_t which_clock = restart_block->nanosleep.clockid;
1529         struct timespec t;
1530         struct itimerspec it;
1531         int error;
1532
1533         t = ns_to_timespec(restart_block->nanosleep.expires);
1534
1535         error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1536
1537         if (error == -ERESTART_RESTARTBLOCK) {
1538                 struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1539                 /*
1540                  * Report back to the user the time still remaining.
1541                  */
1542                 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1543                         return -EFAULT;
1544
1545                 restart_block->nanosleep.expires = timespec_to_ns(&t);
1546         }
1547         return error;
1548
1549 }
1550
1551 #define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1552 #define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1553
1554 static int process_cpu_clock_getres(const clockid_t which_clock,
1555                                     struct timespec *tp)
1556 {
1557         return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1558 }
1559 static int process_cpu_clock_get(const clockid_t which_clock,
1560                                  struct timespec *tp)
1561 {
1562         return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1563 }
1564 static int process_cpu_timer_create(struct k_itimer *timer)
1565 {
1566         timer->it_clock = PROCESS_CLOCK;
1567         return posix_cpu_timer_create(timer);
1568 }
1569 static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1570                               struct timespec *rqtp,
1571                               struct timespec __user *rmtp)
1572 {
1573         return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1574 }
1575 static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1576 {
1577         return -EINVAL;
1578 }
1579 static int thread_cpu_clock_getres(const clockid_t which_clock,
1580                                    struct timespec *tp)
1581 {
1582         return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1583 }
1584 static int thread_cpu_clock_get(const clockid_t which_clock,
1585                                 struct timespec *tp)
1586 {
1587         return posix_cpu_clock_get(THREAD_CLOCK, tp);
1588 }
1589 static int thread_cpu_timer_create(struct k_itimer *timer)
1590 {
1591         timer->it_clock = THREAD_CLOCK;
1592         return posix_cpu_timer_create(timer);
1593 }
1594
1595 struct k_clock clock_posix_cpu = {
1596         .clock_getres   = posix_cpu_clock_getres,
1597         .clock_set      = posix_cpu_clock_set,
1598         .clock_get      = posix_cpu_clock_get,
1599         .timer_create   = posix_cpu_timer_create,
1600         .nsleep         = posix_cpu_nsleep,
1601         .nsleep_restart = posix_cpu_nsleep_restart,
1602         .timer_set      = posix_cpu_timer_set,
1603         .timer_del      = posix_cpu_timer_del,
1604         .timer_get      = posix_cpu_timer_get,
1605 };
1606
1607 static __init int init_posix_cpu_timers(void)
1608 {
1609         struct k_clock process = {
1610                 .clock_getres   = process_cpu_clock_getres,
1611                 .clock_get      = process_cpu_clock_get,
1612                 .timer_create   = process_cpu_timer_create,
1613                 .nsleep         = process_cpu_nsleep,
1614                 .nsleep_restart = process_cpu_nsleep_restart,
1615         };
1616         struct k_clock thread = {
1617                 .clock_getres   = thread_cpu_clock_getres,
1618                 .clock_get      = thread_cpu_clock_get,
1619                 .timer_create   = thread_cpu_timer_create,
1620         };
1621         struct timespec ts;
1622
1623         posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1624         posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1625
1626         cputime_to_timespec(cputime_one_jiffy, &ts);
1627         onecputick = ts.tv_nsec;
1628         WARN_ON(ts.tv_sec != 0);
1629
1630         return 0;
1631 }
1632 __initcall(init_posix_cpu_timers);