cpu-timers: Simplify RLIMIT_CPU handling
[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(unsigned long rlim_new)
20 {
21         cputime_t cputime = secs_to_cputime(rlim_new);
22
23         spin_lock_irq(&current->sighand->siglock);
24         set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
25         spin_unlock_irq(&current->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         read_lock(&tasklist_lock);
41         p = find_task_by_vpid(pid);
42         if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
43                    same_thread_group(p, current) : thread_group_leader(p))) {
44                 error = -EINVAL;
45         }
46         read_unlock(&tasklist_lock);
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 int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
180 {
181         int error = check_clock(which_clock);
182         if (!error) {
183                 tp->tv_sec = 0;
184                 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
185                 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
186                         /*
187                          * If sched_clock is using a cycle counter, we
188                          * don't have any idea of its true resolution
189                          * exported, but it is much more than 1s/HZ.
190                          */
191                         tp->tv_nsec = 1;
192                 }
193         }
194         return error;
195 }
196
197 int posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
198 {
199         /*
200          * You can never reset a CPU clock, but we check for other errors
201          * in the call before failing with EPERM.
202          */
203         int error = check_clock(which_clock);
204         if (error == 0) {
205                 error = -EPERM;
206         }
207         return error;
208 }
209
210
211 /*
212  * Sample a per-thread clock for the given task.
213  */
214 static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
215                             union cpu_time_count *cpu)
216 {
217         switch (CPUCLOCK_WHICH(which_clock)) {
218         default:
219                 return -EINVAL;
220         case CPUCLOCK_PROF:
221                 cpu->cpu = prof_ticks(p);
222                 break;
223         case CPUCLOCK_VIRT:
224                 cpu->cpu = virt_ticks(p);
225                 break;
226         case CPUCLOCK_SCHED:
227                 cpu->sched = task_sched_runtime(p);
228                 break;
229         }
230         return 0;
231 }
232
233 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
234 {
235         struct sighand_struct *sighand;
236         struct signal_struct *sig;
237         struct task_struct *t;
238
239         *times = INIT_CPUTIME;
240
241         rcu_read_lock();
242         sighand = rcu_dereference(tsk->sighand);
243         if (!sighand)
244                 goto out;
245
246         sig = tsk->signal;
247
248         t = tsk;
249         do {
250                 times->utime = cputime_add(times->utime, t->utime);
251                 times->stime = cputime_add(times->stime, t->stime);
252                 times->sum_exec_runtime += t->se.sum_exec_runtime;
253
254                 t = next_thread(t);
255         } while (t != tsk);
256
257         times->utime = cputime_add(times->utime, sig->utime);
258         times->stime = cputime_add(times->stime, sig->stime);
259         times->sum_exec_runtime += sig->sum_sched_runtime;
260 out:
261         rcu_read_unlock();
262 }
263
264 static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
265 {
266         if (cputime_gt(b->utime, a->utime))
267                 a->utime = b->utime;
268
269         if (cputime_gt(b->stime, a->stime))
270                 a->stime = b->stime;
271
272         if (b->sum_exec_runtime > a->sum_exec_runtime)
273                 a->sum_exec_runtime = b->sum_exec_runtime;
274 }
275
276 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
277 {
278         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
279         struct task_cputime sum;
280         unsigned long flags;
281
282         spin_lock_irqsave(&cputimer->lock, flags);
283         if (!cputimer->running) {
284                 cputimer->running = 1;
285                 /*
286                  * The POSIX timer interface allows for absolute time expiry
287                  * values through the TIMER_ABSTIME flag, therefore we have
288                  * to synchronize the timer to the clock every time we start
289                  * it.
290                  */
291                 thread_group_cputime(tsk, &sum);
292                 update_gt_cputime(&cputimer->cputime, &sum);
293         }
294         *times = cputimer->cputime;
295         spin_unlock_irqrestore(&cputimer->lock, flags);
296 }
297
298 /*
299  * Sample a process (thread group) clock for the given group_leader task.
300  * Must be called with tasklist_lock held for reading.
301  */
302 static int cpu_clock_sample_group(const clockid_t which_clock,
303                                   struct task_struct *p,
304                                   union cpu_time_count *cpu)
305 {
306         struct task_cputime cputime;
307
308         switch (CPUCLOCK_WHICH(which_clock)) {
309         default:
310                 return -EINVAL;
311         case CPUCLOCK_PROF:
312                 thread_group_cputime(p, &cputime);
313                 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
314                 break;
315         case CPUCLOCK_VIRT:
316                 thread_group_cputime(p, &cputime);
317                 cpu->cpu = cputime.utime;
318                 break;
319         case CPUCLOCK_SCHED:
320                 cpu->sched = thread_group_sched_runtime(p);
321                 break;
322         }
323         return 0;
324 }
325
326
327 int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
328 {
329         const pid_t pid = CPUCLOCK_PID(which_clock);
330         int error = -EINVAL;
331         union cpu_time_count rtn;
332
333         if (pid == 0) {
334                 /*
335                  * Special case constant value for our own clocks.
336                  * We don't have to do any lookup to find ourselves.
337                  */
338                 if (CPUCLOCK_PERTHREAD(which_clock)) {
339                         /*
340                          * Sampling just ourselves we can do with no locking.
341                          */
342                         error = cpu_clock_sample(which_clock,
343                                                  current, &rtn);
344                 } else {
345                         read_lock(&tasklist_lock);
346                         error = cpu_clock_sample_group(which_clock,
347                                                        current, &rtn);
348                         read_unlock(&tasklist_lock);
349                 }
350         } else {
351                 /*
352                  * Find the given PID, and validate that the caller
353                  * should be able to see it.
354                  */
355                 struct task_struct *p;
356                 rcu_read_lock();
357                 p = find_task_by_vpid(pid);
358                 if (p) {
359                         if (CPUCLOCK_PERTHREAD(which_clock)) {
360                                 if (same_thread_group(p, current)) {
361                                         error = cpu_clock_sample(which_clock,
362                                                                  p, &rtn);
363                                 }
364                         } else {
365                                 read_lock(&tasklist_lock);
366                                 if (thread_group_leader(p) && p->signal) {
367                                         error =
368                                             cpu_clock_sample_group(which_clock,
369                                                                    p, &rtn);
370                                 }
371                                 read_unlock(&tasklist_lock);
372                         }
373                 }
374                 rcu_read_unlock();
375         }
376
377         if (error)
378                 return error;
379         sample_to_timespec(which_clock, rtn, tp);
380         return 0;
381 }
382
383
384 /*
385  * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
386  * This is called from sys_timer_create() and do_cpu_nanosleep() with the
387  * new timer already all-zeros initialized.
388  */
389 int posix_cpu_timer_create(struct k_itimer *new_timer)
390 {
391         int ret = 0;
392         const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
393         struct task_struct *p;
394
395         if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
396                 return -EINVAL;
397
398         INIT_LIST_HEAD(&new_timer->it.cpu.entry);
399
400         read_lock(&tasklist_lock);
401         if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
402                 if (pid == 0) {
403                         p = current;
404                 } else {
405                         p = find_task_by_vpid(pid);
406                         if (p && !same_thread_group(p, current))
407                                 p = NULL;
408                 }
409         } else {
410                 if (pid == 0) {
411                         p = current->group_leader;
412                 } else {
413                         p = find_task_by_vpid(pid);
414                         if (p && !thread_group_leader(p))
415                                 p = NULL;
416                 }
417         }
418         new_timer->it.cpu.task = p;
419         if (p) {
420                 get_task_struct(p);
421         } else {
422                 ret = -EINVAL;
423         }
424         read_unlock(&tasklist_lock);
425
426         return ret;
427 }
428
429 /*
430  * Clean up a CPU-clock timer that is about to be destroyed.
431  * This is called from timer deletion with the timer already locked.
432  * If we return TIMER_RETRY, it's necessary to release the timer's lock
433  * and try again.  (This happens when the timer is in the middle of firing.)
434  */
435 int posix_cpu_timer_del(struct k_itimer *timer)
436 {
437         struct task_struct *p = timer->it.cpu.task;
438         int ret = 0;
439
440         if (likely(p != NULL)) {
441                 read_lock(&tasklist_lock);
442                 if (unlikely(p->signal == NULL)) {
443                         /*
444                          * We raced with the reaping of the task.
445                          * The deletion should have cleared us off the list.
446                          */
447                         BUG_ON(!list_empty(&timer->it.cpu.entry));
448                 } else {
449                         spin_lock(&p->sighand->siglock);
450                         if (timer->it.cpu.firing)
451                                 ret = TIMER_RETRY;
452                         else
453                                 list_del(&timer->it.cpu.entry);
454                         spin_unlock(&p->sighand->siglock);
455                 }
456                 read_unlock(&tasklist_lock);
457
458                 if (!ret)
459                         put_task_struct(p);
460         }
461
462         return ret;
463 }
464
465 /*
466  * Clean out CPU timers still ticking when a thread exited.  The task
467  * pointer is cleared, and the expiry time is replaced with the residual
468  * time for later timer_gettime calls to return.
469  * This must be called with the siglock held.
470  */
471 static void cleanup_timers(struct list_head *head,
472                            cputime_t utime, cputime_t stime,
473                            unsigned long long sum_exec_runtime)
474 {
475         struct cpu_timer_list *timer, *next;
476         cputime_t ptime = cputime_add(utime, stime);
477
478         list_for_each_entry_safe(timer, next, head, entry) {
479                 list_del_init(&timer->entry);
480                 if (cputime_lt(timer->expires.cpu, ptime)) {
481                         timer->expires.cpu = cputime_zero;
482                 } else {
483                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
484                                                          ptime);
485                 }
486         }
487
488         ++head;
489         list_for_each_entry_safe(timer, next, head, entry) {
490                 list_del_init(&timer->entry);
491                 if (cputime_lt(timer->expires.cpu, utime)) {
492                         timer->expires.cpu = cputime_zero;
493                 } else {
494                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
495                                                          utime);
496                 }
497         }
498
499         ++head;
500         list_for_each_entry_safe(timer, next, head, entry) {
501                 list_del_init(&timer->entry);
502                 if (timer->expires.sched < sum_exec_runtime) {
503                         timer->expires.sched = 0;
504                 } else {
505                         timer->expires.sched -= sum_exec_runtime;
506                 }
507         }
508 }
509
510 /*
511  * These are both called with the siglock held, when the current thread
512  * is being reaped.  When the final (leader) thread in the group is reaped,
513  * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
514  */
515 void posix_cpu_timers_exit(struct task_struct *tsk)
516 {
517         cleanup_timers(tsk->cpu_timers,
518                        tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
519
520 }
521 void posix_cpu_timers_exit_group(struct task_struct *tsk)
522 {
523         struct signal_struct *const sig = tsk->signal;
524
525         cleanup_timers(tsk->signal->cpu_timers,
526                        cputime_add(tsk->utime, sig->utime),
527                        cputime_add(tsk->stime, sig->stime),
528                        tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
529 }
530
531 static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
532 {
533         /*
534          * That's all for this thread or process.
535          * We leave our residual in expires to be reported.
536          */
537         put_task_struct(timer->it.cpu.task);
538         timer->it.cpu.task = NULL;
539         timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
540                                              timer->it.cpu.expires,
541                                              now);
542 }
543
544 static inline int expires_gt(cputime_t expires, cputime_t new_exp)
545 {
546         return cputime_eq(expires, cputime_zero) ||
547                cputime_gt(expires, new_exp);
548 }
549
550 static inline int expires_le(cputime_t expires, cputime_t new_exp)
551 {
552         return !cputime_eq(expires, cputime_zero) &&
553                cputime_le(expires, new_exp);
554 }
555 /*
556  * Insert the timer on the appropriate list before any timers that
557  * expire later.  This must be called with the tasklist_lock held
558  * for reading, and interrupts disabled.
559  */
560 static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
561 {
562         struct task_struct *p = timer->it.cpu.task;
563         struct list_head *head, *listpos;
564         struct cpu_timer_list *const nt = &timer->it.cpu;
565         struct cpu_timer_list *next;
566
567         head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?
568                 p->cpu_timers : p->signal->cpu_timers);
569         head += CPUCLOCK_WHICH(timer->it_clock);
570
571         BUG_ON(!irqs_disabled());
572         spin_lock(&p->sighand->siglock);
573
574         listpos = head;
575         if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
576                 list_for_each_entry(next, head, entry) {
577                         if (next->expires.sched > nt->expires.sched)
578                                 break;
579                         listpos = &next->entry;
580                 }
581         } else {
582                 list_for_each_entry(next, head, entry) {
583                         if (cputime_gt(next->expires.cpu, nt->expires.cpu))
584                                 break;
585                         listpos = &next->entry;
586                 }
587         }
588         list_add(&nt->entry, listpos);
589
590         if (listpos == head) {
591                 /*
592                  * We are the new earliest-expiring timer.
593                  * If we are a thread timer, there can always
594                  * be a process timer telling us to stop earlier.
595                  */
596
597                 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
598                         union cpu_time_count *exp = &nt->expires;
599
600                         switch (CPUCLOCK_WHICH(timer->it_clock)) {
601                         default:
602                                 BUG();
603                         case CPUCLOCK_PROF:
604                                 if (expires_gt(p->cputime_expires.prof_exp,
605                                                exp->cpu))
606                                         p->cputime_expires.prof_exp = exp->cpu;
607                                 break;
608                         case CPUCLOCK_VIRT:
609                                 if (expires_gt(p->cputime_expires.virt_exp,
610                                                exp->cpu))
611                                         p->cputime_expires.virt_exp = exp->cpu;
612                                 break;
613                         case CPUCLOCK_SCHED:
614                                 if (p->cputime_expires.sched_exp == 0 ||
615                                     p->cputime_expires.sched_exp > exp->sched)
616                                         p->cputime_expires.sched_exp =
617                                                                 exp->sched;
618                                 break;
619                         }
620                 } else {
621                         struct signal_struct *const sig = p->signal;
622                         union cpu_time_count *exp = &timer->it.cpu.expires;
623
624                         /*
625                          * For a process timer, set the cached expiration time.
626                          */
627                         switch (CPUCLOCK_WHICH(timer->it_clock)) {
628                         default:
629                                 BUG();
630                         case CPUCLOCK_VIRT:
631                                 if (expires_gt(sig->cputime_expires.virt_exp, exp->cpu))
632                                         sig->cputime_expires.virt_exp = exp->cpu;
633                         case CPUCLOCK_PROF:
634                                 if (expires_gt(sig->cputime_expires.prof_exp, exp->cpu))
635                                         sig->cputime_expires.prof_exp = exp->cpu;
636                                 break;
637                         case CPUCLOCK_SCHED:
638                                 sig->cputime_expires.sched_exp = exp->sched;
639                                 break;
640                         }
641                 }
642         }
643
644         spin_unlock(&p->sighand->siglock);
645 }
646
647 /*
648  * The timer is locked, fire it and arrange for its reload.
649  */
650 static void cpu_timer_fire(struct k_itimer *timer)
651 {
652         if (unlikely(timer->sigq == NULL)) {
653                 /*
654                  * This a special case for clock_nanosleep,
655                  * not a normal timer from sys_timer_create.
656                  */
657                 wake_up_process(timer->it_process);
658                 timer->it.cpu.expires.sched = 0;
659         } else if (timer->it.cpu.incr.sched == 0) {
660                 /*
661                  * One-shot timer.  Clear it as soon as it's fired.
662                  */
663                 posix_timer_event(timer, 0);
664                 timer->it.cpu.expires.sched = 0;
665         } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
666                 /*
667                  * The signal did not get queued because the signal
668                  * was ignored, so we won't get any callback to
669                  * reload the timer.  But we need to keep it
670                  * ticking in case the signal is deliverable next time.
671                  */
672                 posix_cpu_timer_schedule(timer);
673         }
674 }
675
676 /*
677  * Sample a process (thread group) timer for the given group_leader task.
678  * Must be called with tasklist_lock held for reading.
679  */
680 static int cpu_timer_sample_group(const clockid_t which_clock,
681                                   struct task_struct *p,
682                                   union cpu_time_count *cpu)
683 {
684         struct task_cputime cputime;
685
686         thread_group_cputimer(p, &cputime);
687         switch (CPUCLOCK_WHICH(which_clock)) {
688         default:
689                 return -EINVAL;
690         case CPUCLOCK_PROF:
691                 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
692                 break;
693         case CPUCLOCK_VIRT:
694                 cpu->cpu = cputime.utime;
695                 break;
696         case CPUCLOCK_SCHED:
697                 cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
698                 break;
699         }
700         return 0;
701 }
702
703 /*
704  * Guts of sys_timer_settime for CPU timers.
705  * This is called with the timer locked and interrupts disabled.
706  * If we return TIMER_RETRY, it's necessary to release the timer's lock
707  * and try again.  (This happens when the timer is in the middle of firing.)
708  */
709 int posix_cpu_timer_set(struct k_itimer *timer, int flags,
710                         struct itimerspec *new, struct itimerspec *old)
711 {
712         struct task_struct *p = timer->it.cpu.task;
713         union cpu_time_count old_expires, new_expires, val;
714         int ret;
715
716         if (unlikely(p == NULL)) {
717                 /*
718                  * Timer refers to a dead task's clock.
719                  */
720                 return -ESRCH;
721         }
722
723         new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
724
725         read_lock(&tasklist_lock);
726         /*
727          * We need the tasklist_lock to protect against reaping that
728          * clears p->signal.  If p has just been reaped, we can no
729          * longer get any information about it at all.
730          */
731         if (unlikely(p->signal == NULL)) {
732                 read_unlock(&tasklist_lock);
733                 put_task_struct(p);
734                 timer->it.cpu.task = NULL;
735                 return -ESRCH;
736         }
737
738         /*
739          * Disarm any old timer after extracting its expiry time.
740          */
741         BUG_ON(!irqs_disabled());
742
743         ret = 0;
744         spin_lock(&p->sighand->siglock);
745         old_expires = timer->it.cpu.expires;
746         if (unlikely(timer->it.cpu.firing)) {
747                 timer->it.cpu.firing = -1;
748                 ret = TIMER_RETRY;
749         } else
750                 list_del_init(&timer->it.cpu.entry);
751         spin_unlock(&p->sighand->siglock);
752
753         /*
754          * We need to sample the current value to convert the new
755          * value from to relative and absolute, and to convert the
756          * old value from absolute to relative.  To set a process
757          * timer, we need a sample to balance the thread expiry
758          * times (in arm_timer).  With an absolute time, we must
759          * check if it's already passed.  In short, we need a sample.
760          */
761         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
762                 cpu_clock_sample(timer->it_clock, p, &val);
763         } else {
764                 cpu_timer_sample_group(timer->it_clock, p, &val);
765         }
766
767         if (old) {
768                 if (old_expires.sched == 0) {
769                         old->it_value.tv_sec = 0;
770                         old->it_value.tv_nsec = 0;
771                 } else {
772                         /*
773                          * Update the timer in case it has
774                          * overrun already.  If it has,
775                          * we'll report it as having overrun
776                          * and with the next reloaded timer
777                          * already ticking, though we are
778                          * swallowing that pending
779                          * notification here to install the
780                          * new setting.
781                          */
782                         bump_cpu_timer(timer, val);
783                         if (cpu_time_before(timer->it_clock, val,
784                                             timer->it.cpu.expires)) {
785                                 old_expires = cpu_time_sub(
786                                         timer->it_clock,
787                                         timer->it.cpu.expires, val);
788                                 sample_to_timespec(timer->it_clock,
789                                                    old_expires,
790                                                    &old->it_value);
791                         } else {
792                                 old->it_value.tv_nsec = 1;
793                                 old->it_value.tv_sec = 0;
794                         }
795                 }
796         }
797
798         if (unlikely(ret)) {
799                 /*
800                  * We are colliding with the timer actually firing.
801                  * Punt after filling in the timer's old value, and
802                  * disable this firing since we are already reporting
803                  * it as an overrun (thanks to bump_cpu_timer above).
804                  */
805                 read_unlock(&tasklist_lock);
806                 goto out;
807         }
808
809         if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
810                 cpu_time_add(timer->it_clock, &new_expires, val);
811         }
812
813         /*
814          * Install the new expiry time (or zero).
815          * For a timer with no notification action, we don't actually
816          * arm the timer (we'll just fake it for timer_gettime).
817          */
818         timer->it.cpu.expires = new_expires;
819         if (new_expires.sched != 0 &&
820             (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
821             cpu_time_before(timer->it_clock, val, new_expires)) {
822                 arm_timer(timer, val);
823         }
824
825         read_unlock(&tasklist_lock);
826
827         /*
828          * Install the new reload setting, and
829          * set up the signal and overrun bookkeeping.
830          */
831         timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
832                                                 &new->it_interval);
833
834         /*
835          * This acts as a modification timestamp for the timer,
836          * so any automatic reload attempt will punt on seeing
837          * that we have reset the timer manually.
838          */
839         timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
840                 ~REQUEUE_PENDING;
841         timer->it_overrun_last = 0;
842         timer->it_overrun = -1;
843
844         if (new_expires.sched != 0 &&
845             (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
846             !cpu_time_before(timer->it_clock, val, new_expires)) {
847                 /*
848                  * The designated time already passed, so we notify
849                  * immediately, even if the thread never runs to
850                  * accumulate more time on this clock.
851                  */
852                 cpu_timer_fire(timer);
853         }
854
855         ret = 0;
856  out:
857         if (old) {
858                 sample_to_timespec(timer->it_clock,
859                                    timer->it.cpu.incr, &old->it_interval);
860         }
861         return ret;
862 }
863
864 void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
865 {
866         union cpu_time_count now;
867         struct task_struct *p = timer->it.cpu.task;
868         int clear_dead;
869
870         /*
871          * Easy part: convert the reload time.
872          */
873         sample_to_timespec(timer->it_clock,
874                            timer->it.cpu.incr, &itp->it_interval);
875
876         if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all.  */
877                 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
878                 return;
879         }
880
881         if (unlikely(p == NULL)) {
882                 /*
883                  * This task already died and the timer will never fire.
884                  * In this case, expires is actually the dead value.
885                  */
886         dead:
887                 sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
888                                    &itp->it_value);
889                 return;
890         }
891
892         /*
893          * Sample the clock to take the difference with the expiry time.
894          */
895         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
896                 cpu_clock_sample(timer->it_clock, p, &now);
897                 clear_dead = p->exit_state;
898         } else {
899                 read_lock(&tasklist_lock);
900                 if (unlikely(p->signal == NULL)) {
901                         /*
902                          * The process has been reaped.
903                          * We can't even collect a sample any more.
904                          * Call the timer disarmed, nothing else to do.
905                          */
906                         put_task_struct(p);
907                         timer->it.cpu.task = NULL;
908                         timer->it.cpu.expires.sched = 0;
909                         read_unlock(&tasklist_lock);
910                         goto dead;
911                 } else {
912                         cpu_timer_sample_group(timer->it_clock, p, &now);
913                         clear_dead = (unlikely(p->exit_state) &&
914                                       thread_group_empty(p));
915                 }
916                 read_unlock(&tasklist_lock);
917         }
918
919         if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
920                 if (timer->it.cpu.incr.sched == 0 &&
921                     cpu_time_before(timer->it_clock,
922                                     timer->it.cpu.expires, now)) {
923                         /*
924                          * Do-nothing timer expired and has no reload,
925                          * so it's as if it was never set.
926                          */
927                         timer->it.cpu.expires.sched = 0;
928                         itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
929                         return;
930                 }
931                 /*
932                  * Account for any expirations and reloads that should
933                  * have happened.
934                  */
935                 bump_cpu_timer(timer, now);
936         }
937
938         if (unlikely(clear_dead)) {
939                 /*
940                  * We've noticed that the thread is dead, but
941                  * not yet reaped.  Take this opportunity to
942                  * drop our task ref.
943                  */
944                 clear_dead_task(timer, now);
945                 goto dead;
946         }
947
948         if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
949                 sample_to_timespec(timer->it_clock,
950                                    cpu_time_sub(timer->it_clock,
951                                                 timer->it.cpu.expires, now),
952                                    &itp->it_value);
953         } else {
954                 /*
955                  * The timer should have expired already, but the firing
956                  * hasn't taken place yet.  Say it's just about to expire.
957                  */
958                 itp->it_value.tv_nsec = 1;
959                 itp->it_value.tv_sec = 0;
960         }
961 }
962
963 /*
964  * Check for any per-thread CPU timers that have fired and move them off
965  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
966  * tsk->it_*_expires values to reflect the remaining thread CPU timers.
967  */
968 static void check_thread_timers(struct task_struct *tsk,
969                                 struct list_head *firing)
970 {
971         int maxfire;
972         struct list_head *timers = tsk->cpu_timers;
973         struct signal_struct *const sig = tsk->signal;
974         unsigned long soft;
975
976         maxfire = 20;
977         tsk->cputime_expires.prof_exp = cputime_zero;
978         while (!list_empty(timers)) {
979                 struct cpu_timer_list *t = list_first_entry(timers,
980                                                       struct cpu_timer_list,
981                                                       entry);
982                 if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
983                         tsk->cputime_expires.prof_exp = t->expires.cpu;
984                         break;
985                 }
986                 t->firing = 1;
987                 list_move_tail(&t->entry, firing);
988         }
989
990         ++timers;
991         maxfire = 20;
992         tsk->cputime_expires.virt_exp = cputime_zero;
993         while (!list_empty(timers)) {
994                 struct cpu_timer_list *t = list_first_entry(timers,
995                                                       struct cpu_timer_list,
996                                                       entry);
997                 if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
998                         tsk->cputime_expires.virt_exp = t->expires.cpu;
999                         break;
1000                 }
1001                 t->firing = 1;
1002                 list_move_tail(&t->entry, firing);
1003         }
1004
1005         ++timers;
1006         maxfire = 20;
1007         tsk->cputime_expires.sched_exp = 0;
1008         while (!list_empty(timers)) {
1009                 struct cpu_timer_list *t = list_first_entry(timers,
1010                                                       struct cpu_timer_list,
1011                                                       entry);
1012                 if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
1013                         tsk->cputime_expires.sched_exp = t->expires.sched;
1014                         break;
1015                 }
1016                 t->firing = 1;
1017                 list_move_tail(&t->entry, firing);
1018         }
1019
1020         /*
1021          * Check for the special case thread timers.
1022          */
1023         soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
1024         if (soft != RLIM_INFINITY) {
1025                 unsigned long hard =
1026                         ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
1027
1028                 if (hard != RLIM_INFINITY &&
1029                     tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
1030                         /*
1031                          * At the hard limit, we just die.
1032                          * No need to calculate anything else now.
1033                          */
1034                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1035                         return;
1036                 }
1037                 if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
1038                         /*
1039                          * At the soft limit, send a SIGXCPU every second.
1040                          */
1041                         if (soft < hard) {
1042                                 soft += USEC_PER_SEC;
1043                                 sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
1044                         }
1045                         printk(KERN_INFO
1046                                 "RT Watchdog Timeout: %s[%d]\n",
1047                                 tsk->comm, task_pid_nr(tsk));
1048                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1049                 }
1050         }
1051 }
1052
1053 static void stop_process_timers(struct task_struct *tsk)
1054 {
1055         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
1056         unsigned long flags;
1057
1058         if (!cputimer->running)
1059                 return;
1060
1061         spin_lock_irqsave(&cputimer->lock, flags);
1062         cputimer->running = 0;
1063         spin_unlock_irqrestore(&cputimer->lock, flags);
1064 }
1065
1066 static u32 onecputick;
1067
1068 static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
1069                              cputime_t *expires, cputime_t cur_time, int signo)
1070 {
1071         if (cputime_eq(it->expires, cputime_zero))
1072                 return;
1073
1074         if (cputime_ge(cur_time, it->expires)) {
1075                 if (!cputime_eq(it->incr, cputime_zero)) {
1076                         it->expires = cputime_add(it->expires, it->incr);
1077                         it->error += it->incr_error;
1078                         if (it->error >= onecputick) {
1079                                 it->expires = cputime_sub(it->expires,
1080                                                           cputime_one_jiffy);
1081                                 it->error -= onecputick;
1082                         }
1083                 } else {
1084                         it->expires = cputime_zero;
1085                 }
1086
1087                 trace_itimer_expire(signo == SIGPROF ?
1088                                     ITIMER_PROF : ITIMER_VIRTUAL,
1089                                     tsk->signal->leader_pid, cur_time);
1090                 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
1091         }
1092
1093         if (!cputime_eq(it->expires, cputime_zero) &&
1094             (cputime_eq(*expires, cputime_zero) ||
1095              cputime_lt(it->expires, *expires))) {
1096                 *expires = it->expires;
1097         }
1098 }
1099
1100 /*
1101  * Check for any per-thread CPU timers that have fired and move them
1102  * off the tsk->*_timers list onto the firing list.  Per-thread timers
1103  * have already been taken off.
1104  */
1105 static void check_process_timers(struct task_struct *tsk,
1106                                  struct list_head *firing)
1107 {
1108         int maxfire;
1109         struct signal_struct *const sig = tsk->signal;
1110         cputime_t utime, ptime, virt_expires, prof_expires;
1111         unsigned long long sum_sched_runtime, sched_expires;
1112         struct list_head *timers = sig->cpu_timers;
1113         struct task_cputime cputime;
1114         unsigned long soft;
1115
1116         /*
1117          * Don't sample the current process CPU clocks if there are no timers.
1118          */
1119         if (list_empty(&timers[CPUCLOCK_PROF]) &&
1120             cputime_eq(sig->it[CPUCLOCK_PROF].expires, cputime_zero) &&
1121             sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&
1122             list_empty(&timers[CPUCLOCK_VIRT]) &&
1123             cputime_eq(sig->it[CPUCLOCK_VIRT].expires, cputime_zero) &&
1124             list_empty(&timers[CPUCLOCK_SCHED])) {
1125                 stop_process_timers(tsk);
1126                 return;
1127         }
1128
1129         /*
1130          * Collect the current process totals.
1131          */
1132         thread_group_cputimer(tsk, &cputime);
1133         utime = cputime.utime;
1134         ptime = cputime_add(utime, cputime.stime);
1135         sum_sched_runtime = cputime.sum_exec_runtime;
1136         maxfire = 20;
1137         prof_expires = cputime_zero;
1138         while (!list_empty(timers)) {
1139                 struct cpu_timer_list *tl = list_first_entry(timers,
1140                                                       struct cpu_timer_list,
1141                                                       entry);
1142                 if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) {
1143                         prof_expires = tl->expires.cpu;
1144                         break;
1145                 }
1146                 tl->firing = 1;
1147                 list_move_tail(&tl->entry, firing);
1148         }
1149
1150         ++timers;
1151         maxfire = 20;
1152         virt_expires = cputime_zero;
1153         while (!list_empty(timers)) {
1154                 struct cpu_timer_list *tl = list_first_entry(timers,
1155                                                       struct cpu_timer_list,
1156                                                       entry);
1157                 if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) {
1158                         virt_expires = tl->expires.cpu;
1159                         break;
1160                 }
1161                 tl->firing = 1;
1162                 list_move_tail(&tl->entry, firing);
1163         }
1164
1165         ++timers;
1166         maxfire = 20;
1167         sched_expires = 0;
1168         while (!list_empty(timers)) {
1169                 struct cpu_timer_list *tl = list_first_entry(timers,
1170                                                       struct cpu_timer_list,
1171                                                       entry);
1172                 if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1173                         sched_expires = tl->expires.sched;
1174                         break;
1175                 }
1176                 tl->firing = 1;
1177                 list_move_tail(&tl->entry, firing);
1178         }
1179
1180         /*
1181          * Check for the special case process timers.
1182          */
1183         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1184                          SIGPROF);
1185         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1186                          SIGVTALRM);
1187         soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1188         if (soft != RLIM_INFINITY) {
1189                 unsigned long psecs = cputime_to_secs(ptime);
1190                 unsigned long hard =
1191                         ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
1192                 cputime_t x;
1193                 if (psecs >= hard) {
1194                         /*
1195                          * At the hard limit, we just die.
1196                          * No need to calculate anything else now.
1197                          */
1198                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1199                         return;
1200                 }
1201                 if (psecs >= soft) {
1202                         /*
1203                          * At the soft limit, send a SIGXCPU every second.
1204                          */
1205                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1206                         if (soft < hard) {
1207                                 soft++;
1208                                 sig->rlim[RLIMIT_CPU].rlim_cur = soft;
1209                         }
1210                 }
1211                 x = secs_to_cputime(soft);
1212                 if (cputime_eq(prof_expires, cputime_zero) ||
1213                     cputime_lt(x, prof_expires)) {
1214                         prof_expires = x;
1215                 }
1216         }
1217
1218         if (!cputime_eq(prof_expires, cputime_zero) &&
1219             (cputime_eq(sig->cputime_expires.prof_exp, cputime_zero) ||
1220              cputime_gt(sig->cputime_expires.prof_exp, prof_expires)))
1221                 sig->cputime_expires.prof_exp = prof_expires;
1222         if (!cputime_eq(virt_expires, cputime_zero) &&
1223             (cputime_eq(sig->cputime_expires.virt_exp, cputime_zero) ||
1224              cputime_gt(sig->cputime_expires.virt_exp, virt_expires)))
1225                 sig->cputime_expires.virt_exp = virt_expires;
1226         if (sched_expires != 0 &&
1227             (sig->cputime_expires.sched_exp == 0 ||
1228              sig->cputime_expires.sched_exp > sched_expires))
1229                 sig->cputime_expires.sched_exp = sched_expires;
1230 }
1231
1232 /*
1233  * This is called from the signal code (via do_schedule_next_timer)
1234  * when the last timer signal was delivered and we have to reload the timer.
1235  */
1236 void posix_cpu_timer_schedule(struct k_itimer *timer)
1237 {
1238         struct task_struct *p = timer->it.cpu.task;
1239         union cpu_time_count now;
1240
1241         if (unlikely(p == NULL))
1242                 /*
1243                  * The task was cleaned up already, no future firings.
1244                  */
1245                 goto out;
1246
1247         /*
1248          * Fetch the current sample and update the timer's expiry time.
1249          */
1250         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1251                 cpu_clock_sample(timer->it_clock, p, &now);
1252                 bump_cpu_timer(timer, now);
1253                 if (unlikely(p->exit_state)) {
1254                         clear_dead_task(timer, now);
1255                         goto out;
1256                 }
1257                 read_lock(&tasklist_lock); /* arm_timer needs it.  */
1258         } else {
1259                 read_lock(&tasklist_lock);
1260                 if (unlikely(p->signal == NULL)) {
1261                         /*
1262                          * The process has been reaped.
1263                          * We can't even collect a sample any more.
1264                          */
1265                         put_task_struct(p);
1266                         timer->it.cpu.task = p = NULL;
1267                         timer->it.cpu.expires.sched = 0;
1268                         goto out_unlock;
1269                 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1270                         /*
1271                          * We've noticed that the thread is dead, but
1272                          * not yet reaped.  Take this opportunity to
1273                          * drop our task ref.
1274                          */
1275                         clear_dead_task(timer, now);
1276                         goto out_unlock;
1277                 }
1278                 cpu_timer_sample_group(timer->it_clock, p, &now);
1279                 bump_cpu_timer(timer, now);
1280                 /* Leave the tasklist_lock locked for the call below.  */
1281         }
1282
1283         /*
1284          * Now re-arm for the new expiry time.
1285          */
1286         arm_timer(timer, now);
1287
1288 out_unlock:
1289         read_unlock(&tasklist_lock);
1290
1291 out:
1292         timer->it_overrun_last = timer->it_overrun;
1293         timer->it_overrun = -1;
1294         ++timer->it_requeue_pending;
1295 }
1296
1297 /**
1298  * task_cputime_zero - Check a task_cputime struct for all zero fields.
1299  *
1300  * @cputime:    The struct to compare.
1301  *
1302  * Checks @cputime to see if all fields are zero.  Returns true if all fields
1303  * are zero, false if any field is nonzero.
1304  */
1305 static inline int task_cputime_zero(const struct task_cputime *cputime)
1306 {
1307         if (cputime_eq(cputime->utime, cputime_zero) &&
1308             cputime_eq(cputime->stime, cputime_zero) &&
1309             cputime->sum_exec_runtime == 0)
1310                 return 1;
1311         return 0;
1312 }
1313
1314 /**
1315  * task_cputime_expired - Compare two task_cputime entities.
1316  *
1317  * @sample:     The task_cputime structure to be checked for expiration.
1318  * @expires:    Expiration times, against which @sample will be checked.
1319  *
1320  * Checks @sample against @expires to see if any field of @sample has expired.
1321  * Returns true if any field of the former is greater than the corresponding
1322  * field of the latter if the latter field is set.  Otherwise returns false.
1323  */
1324 static inline int task_cputime_expired(const struct task_cputime *sample,
1325                                         const struct task_cputime *expires)
1326 {
1327         if (!cputime_eq(expires->utime, cputime_zero) &&
1328             cputime_ge(sample->utime, expires->utime))
1329                 return 1;
1330         if (!cputime_eq(expires->stime, cputime_zero) &&
1331             cputime_ge(cputime_add(sample->utime, sample->stime),
1332                        expires->stime))
1333                 return 1;
1334         if (expires->sum_exec_runtime != 0 &&
1335             sample->sum_exec_runtime >= expires->sum_exec_runtime)
1336                 return 1;
1337         return 0;
1338 }
1339
1340 /**
1341  * fastpath_timer_check - POSIX CPU timers fast path.
1342  *
1343  * @tsk:        The task (thread) being checked.
1344  *
1345  * Check the task and thread group timers.  If both are zero (there are no
1346  * timers set) return false.  Otherwise snapshot the task and thread group
1347  * timers and compare them with the corresponding expiration times.  Return
1348  * true if a timer has expired, else return false.
1349  */
1350 static inline int fastpath_timer_check(struct task_struct *tsk)
1351 {
1352         struct signal_struct *sig;
1353
1354         /* tsk == current, ensure it is safe to use ->signal/sighand */
1355         if (unlikely(tsk->exit_state))
1356                 return 0;
1357
1358         if (!task_cputime_zero(&tsk->cputime_expires)) {
1359                 struct task_cputime task_sample = {
1360                         .utime = tsk->utime,
1361                         .stime = tsk->stime,
1362                         .sum_exec_runtime = tsk->se.sum_exec_runtime
1363                 };
1364
1365                 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1366                         return 1;
1367         }
1368
1369         sig = tsk->signal;
1370         if (!task_cputime_zero(&sig->cputime_expires)) {
1371                 struct task_cputime group_sample;
1372
1373                 thread_group_cputimer(tsk, &group_sample);
1374                 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1375                         return 1;
1376         }
1377
1378         return 0;
1379 }
1380
1381 /*
1382  * This is called from the timer interrupt handler.  The irq handler has
1383  * already updated our counts.  We need to check if any timers fire now.
1384  * Interrupts are disabled.
1385  */
1386 void run_posix_cpu_timers(struct task_struct *tsk)
1387 {
1388         LIST_HEAD(firing);
1389         struct k_itimer *timer, *next;
1390
1391         BUG_ON(!irqs_disabled());
1392
1393         /*
1394          * The fast path checks that there are no expired thread or thread
1395          * group timers.  If that's so, just return.
1396          */
1397         if (!fastpath_timer_check(tsk))
1398                 return;
1399
1400         spin_lock(&tsk->sighand->siglock);
1401         /*
1402          * Here we take off tsk->signal->cpu_timers[N] and
1403          * tsk->cpu_timers[N] all the timers that are firing, and
1404          * put them on the firing list.
1405          */
1406         check_thread_timers(tsk, &firing);
1407         check_process_timers(tsk, &firing);
1408
1409         /*
1410          * We must release these locks before taking any timer's lock.
1411          * There is a potential race with timer deletion here, as the
1412          * siglock now protects our private firing list.  We have set
1413          * the firing flag in each timer, so that a deletion attempt
1414          * that gets the timer lock before we do will give it up and
1415          * spin until we've taken care of that timer below.
1416          */
1417         spin_unlock(&tsk->sighand->siglock);
1418
1419         /*
1420          * Now that all the timers on our list have the firing flag,
1421          * noone will touch their list entries but us.  We'll take
1422          * each timer's lock before clearing its firing flag, so no
1423          * timer call will interfere.
1424          */
1425         list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1426                 int cpu_firing;
1427
1428                 spin_lock(&timer->it_lock);
1429                 list_del_init(&timer->it.cpu.entry);
1430                 cpu_firing = timer->it.cpu.firing;
1431                 timer->it.cpu.firing = 0;
1432                 /*
1433                  * The firing flag is -1 if we collided with a reset
1434                  * of the timer, which already reported this
1435                  * almost-firing as an overrun.  So don't generate an event.
1436                  */
1437                 if (likely(cpu_firing >= 0))
1438                         cpu_timer_fire(timer);
1439                 spin_unlock(&timer->it_lock);
1440         }
1441 }
1442
1443 /*
1444  * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1445  * The tsk->sighand->siglock must be held by the caller.
1446  */
1447 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1448                            cputime_t *newval, cputime_t *oldval)
1449 {
1450         union cpu_time_count now;
1451
1452         BUG_ON(clock_idx == CPUCLOCK_SCHED);
1453         cpu_timer_sample_group(clock_idx, tsk, &now);
1454
1455         if (oldval) {
1456                 /*
1457                  * We are setting itimer. The *oldval is absolute and we update
1458                  * it to be relative, *newval argument is relative and we update
1459                  * it to be absolute.
1460                  */
1461                 if (!cputime_eq(*oldval, cputime_zero)) {
1462                         if (cputime_le(*oldval, now.cpu)) {
1463                                 /* Just about to fire. */
1464                                 *oldval = cputime_one_jiffy;
1465                         } else {
1466                                 *oldval = cputime_sub(*oldval, now.cpu);
1467                         }
1468                 }
1469
1470                 if (cputime_eq(*newval, cputime_zero))
1471                         return;
1472                 *newval = cputime_add(*newval, now.cpu);
1473         }
1474
1475         /*
1476          * Update expiration cache if we are the earliest timer, or eventually
1477          * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1478          */
1479         switch (clock_idx) {
1480         case CPUCLOCK_PROF:
1481                 if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1482                         tsk->signal->cputime_expires.prof_exp = *newval;
1483                 break;
1484         case CPUCLOCK_VIRT:
1485                 if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1486                         tsk->signal->cputime_expires.virt_exp = *newval;
1487                 break;
1488         }
1489 }
1490
1491 static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1492                             struct timespec *rqtp, struct itimerspec *it)
1493 {
1494         struct k_itimer timer;
1495         int error;
1496
1497         /*
1498          * Set up a temporary timer and then wait for it to go off.
1499          */
1500         memset(&timer, 0, sizeof timer);
1501         spin_lock_init(&timer.it_lock);
1502         timer.it_clock = which_clock;
1503         timer.it_overrun = -1;
1504         error = posix_cpu_timer_create(&timer);
1505         timer.it_process = current;
1506         if (!error) {
1507                 static struct itimerspec zero_it;
1508
1509                 memset(it, 0, sizeof *it);
1510                 it->it_value = *rqtp;
1511
1512                 spin_lock_irq(&timer.it_lock);
1513                 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1514                 if (error) {
1515                         spin_unlock_irq(&timer.it_lock);
1516                         return error;
1517                 }
1518
1519                 while (!signal_pending(current)) {
1520                         if (timer.it.cpu.expires.sched == 0) {
1521                                 /*
1522                                  * Our timer fired and was reset.
1523                                  */
1524                                 spin_unlock_irq(&timer.it_lock);
1525                                 return 0;
1526                         }
1527
1528                         /*
1529                          * Block until cpu_timer_fire (or a signal) wakes us.
1530                          */
1531                         __set_current_state(TASK_INTERRUPTIBLE);
1532                         spin_unlock_irq(&timer.it_lock);
1533                         schedule();
1534                         spin_lock_irq(&timer.it_lock);
1535                 }
1536
1537                 /*
1538                  * We were interrupted by a signal.
1539                  */
1540                 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1541                 posix_cpu_timer_set(&timer, 0, &zero_it, it);
1542                 spin_unlock_irq(&timer.it_lock);
1543
1544                 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1545                         /*
1546                          * It actually did fire already.
1547                          */
1548                         return 0;
1549                 }
1550
1551                 error = -ERESTART_RESTARTBLOCK;
1552         }
1553
1554         return error;
1555 }
1556
1557 int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1558                      struct timespec *rqtp, struct timespec __user *rmtp)
1559 {
1560         struct restart_block *restart_block =
1561             &current_thread_info()->restart_block;
1562         struct itimerspec it;
1563         int error;
1564
1565         /*
1566          * Diagnose required errors first.
1567          */
1568         if (CPUCLOCK_PERTHREAD(which_clock) &&
1569             (CPUCLOCK_PID(which_clock) == 0 ||
1570              CPUCLOCK_PID(which_clock) == current->pid))
1571                 return -EINVAL;
1572
1573         error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1574
1575         if (error == -ERESTART_RESTARTBLOCK) {
1576
1577                 if (flags & TIMER_ABSTIME)
1578                         return -ERESTARTNOHAND;
1579                 /*
1580                  * Report back to the user the time still remaining.
1581                  */
1582                 if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1583                         return -EFAULT;
1584
1585                 restart_block->fn = posix_cpu_nsleep_restart;
1586                 restart_block->arg0 = which_clock;
1587                 restart_block->arg1 = (unsigned long) rmtp;
1588                 restart_block->arg2 = rqtp->tv_sec;
1589                 restart_block->arg3 = rqtp->tv_nsec;
1590         }
1591         return error;
1592 }
1593
1594 long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1595 {
1596         clockid_t which_clock = restart_block->arg0;
1597         struct timespec __user *rmtp;
1598         struct timespec t;
1599         struct itimerspec it;
1600         int error;
1601
1602         rmtp = (struct timespec __user *) restart_block->arg1;
1603         t.tv_sec = restart_block->arg2;
1604         t.tv_nsec = restart_block->arg3;
1605
1606         restart_block->fn = do_no_restart_syscall;
1607         error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1608
1609         if (error == -ERESTART_RESTARTBLOCK) {
1610                 /*
1611                  * Report back to the user the time still remaining.
1612                  */
1613                 if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1614                         return -EFAULT;
1615
1616                 restart_block->fn = posix_cpu_nsleep_restart;
1617                 restart_block->arg0 = which_clock;
1618                 restart_block->arg1 = (unsigned long) rmtp;
1619                 restart_block->arg2 = t.tv_sec;
1620                 restart_block->arg3 = t.tv_nsec;
1621         }
1622         return error;
1623
1624 }
1625
1626
1627 #define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1628 #define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1629
1630 static int process_cpu_clock_getres(const clockid_t which_clock,
1631                                     struct timespec *tp)
1632 {
1633         return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1634 }
1635 static int process_cpu_clock_get(const clockid_t which_clock,
1636                                  struct timespec *tp)
1637 {
1638         return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1639 }
1640 static int process_cpu_timer_create(struct k_itimer *timer)
1641 {
1642         timer->it_clock = PROCESS_CLOCK;
1643         return posix_cpu_timer_create(timer);
1644 }
1645 static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1646                               struct timespec *rqtp,
1647                               struct timespec __user *rmtp)
1648 {
1649         return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1650 }
1651 static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1652 {
1653         return -EINVAL;
1654 }
1655 static int thread_cpu_clock_getres(const clockid_t which_clock,
1656                                    struct timespec *tp)
1657 {
1658         return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1659 }
1660 static int thread_cpu_clock_get(const clockid_t which_clock,
1661                                 struct timespec *tp)
1662 {
1663         return posix_cpu_clock_get(THREAD_CLOCK, tp);
1664 }
1665 static int thread_cpu_timer_create(struct k_itimer *timer)
1666 {
1667         timer->it_clock = THREAD_CLOCK;
1668         return posix_cpu_timer_create(timer);
1669 }
1670 static int thread_cpu_nsleep(const clockid_t which_clock, int flags,
1671                               struct timespec *rqtp, struct timespec __user *rmtp)
1672 {
1673         return -EINVAL;
1674 }
1675 static long thread_cpu_nsleep_restart(struct restart_block *restart_block)
1676 {
1677         return -EINVAL;
1678 }
1679
1680 static __init int init_posix_cpu_timers(void)
1681 {
1682         struct k_clock process = {
1683                 .clock_getres = process_cpu_clock_getres,
1684                 .clock_get = process_cpu_clock_get,
1685                 .clock_set = do_posix_clock_nosettime,
1686                 .timer_create = process_cpu_timer_create,
1687                 .nsleep = process_cpu_nsleep,
1688                 .nsleep_restart = process_cpu_nsleep_restart,
1689         };
1690         struct k_clock thread = {
1691                 .clock_getres = thread_cpu_clock_getres,
1692                 .clock_get = thread_cpu_clock_get,
1693                 .clock_set = do_posix_clock_nosettime,
1694                 .timer_create = thread_cpu_timer_create,
1695                 .nsleep = thread_cpu_nsleep,
1696                 .nsleep_restart = thread_cpu_nsleep_restart,
1697         };
1698         struct timespec ts;
1699
1700         register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1701         register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1702
1703         cputime_to_timespec(cputime_one_jiffy, &ts);
1704         onecputick = ts.tv_nsec;
1705         WARN_ON(ts.tv_sec != 0);
1706
1707         return 0;
1708 }
1709 __initcall(init_posix_cpu_timers);