itimers: Simplify arm_timer() code a bit
[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
12 /*
13  * Called after updating RLIMIT_CPU to set timer expiration if necessary.
14  */
15 void update_rlimit_cpu(unsigned long rlim_new)
16 {
17         cputime_t cputime = secs_to_cputime(rlim_new);
18         struct signal_struct *const sig = current->signal;
19
20         if (cputime_eq(sig->it[CPUCLOCK_PROF].expires, cputime_zero) ||
21             cputime_gt(sig->it[CPUCLOCK_PROF].expires, cputime)) {
22                 spin_lock_irq(&current->sighand->siglock);
23                 set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
24                 spin_unlock_irq(&current->sighand->siglock);
25         }
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 with the new timer already locked.
387  */
388 int posix_cpu_timer_create(struct k_itimer *new_timer)
389 {
390         int ret = 0;
391         const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
392         struct task_struct *p;
393
394         if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
395                 return -EINVAL;
396
397         INIT_LIST_HEAD(&new_timer->it.cpu.entry);
398         new_timer->it.cpu.incr.sched = 0;
399         new_timer->it.cpu.expires.sched = 0;
400
401         read_lock(&tasklist_lock);
402         if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
403                 if (pid == 0) {
404                         p = current;
405                 } else {
406                         p = find_task_by_vpid(pid);
407                         if (p && !same_thread_group(p, current))
408                                 p = NULL;
409                 }
410         } else {
411                 if (pid == 0) {
412                         p = current->group_leader;
413                 } else {
414                         p = find_task_by_vpid(pid);
415                         if (p && !thread_group_leader(p))
416                                 p = NULL;
417                 }
418         }
419         new_timer->it.cpu.task = p;
420         if (p) {
421                 get_task_struct(p);
422         } else {
423                 ret = -EINVAL;
424         }
425         read_unlock(&tasklist_lock);
426
427         return ret;
428 }
429
430 /*
431  * Clean up a CPU-clock timer that is about to be destroyed.
432  * This is called from timer deletion with the timer already locked.
433  * If we return TIMER_RETRY, it's necessary to release the timer's lock
434  * and try again.  (This happens when the timer is in the middle of firing.)
435  */
436 int posix_cpu_timer_del(struct k_itimer *timer)
437 {
438         struct task_struct *p = timer->it.cpu.task;
439         int ret = 0;
440
441         if (likely(p != NULL)) {
442                 read_lock(&tasklist_lock);
443                 if (unlikely(p->signal == NULL)) {
444                         /*
445                          * We raced with the reaping of the task.
446                          * The deletion should have cleared us off the list.
447                          */
448                         BUG_ON(!list_empty(&timer->it.cpu.entry));
449                 } else {
450                         spin_lock(&p->sighand->siglock);
451                         if (timer->it.cpu.firing)
452                                 ret = TIMER_RETRY;
453                         else
454                                 list_del(&timer->it.cpu.entry);
455                         spin_unlock(&p->sighand->siglock);
456                 }
457                 read_unlock(&tasklist_lock);
458
459                 if (!ret)
460                         put_task_struct(p);
461         }
462
463         return ret;
464 }
465
466 /*
467  * Clean out CPU timers still ticking when a thread exited.  The task
468  * pointer is cleared, and the expiry time is replaced with the residual
469  * time for later timer_gettime calls to return.
470  * This must be called with the siglock held.
471  */
472 static void cleanup_timers(struct list_head *head,
473                            cputime_t utime, cputime_t stime,
474                            unsigned long long sum_exec_runtime)
475 {
476         struct cpu_timer_list *timer, *next;
477         cputime_t ptime = cputime_add(utime, stime);
478
479         list_for_each_entry_safe(timer, next, head, entry) {
480                 list_del_init(&timer->entry);
481                 if (cputime_lt(timer->expires.cpu, ptime)) {
482                         timer->expires.cpu = cputime_zero;
483                 } else {
484                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
485                                                          ptime);
486                 }
487         }
488
489         ++head;
490         list_for_each_entry_safe(timer, next, head, entry) {
491                 list_del_init(&timer->entry);
492                 if (cputime_lt(timer->expires.cpu, utime)) {
493                         timer->expires.cpu = cputime_zero;
494                 } else {
495                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
496                                                          utime);
497                 }
498         }
499
500         ++head;
501         list_for_each_entry_safe(timer, next, head, entry) {
502                 list_del_init(&timer->entry);
503                 if (timer->expires.sched < sum_exec_runtime) {
504                         timer->expires.sched = 0;
505                 } else {
506                         timer->expires.sched -= sum_exec_runtime;
507                 }
508         }
509 }
510
511 /*
512  * These are both called with the siglock held, when the current thread
513  * is being reaped.  When the final (leader) thread in the group is reaped,
514  * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
515  */
516 void posix_cpu_timers_exit(struct task_struct *tsk)
517 {
518         cleanup_timers(tsk->cpu_timers,
519                        tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
520
521 }
522 void posix_cpu_timers_exit_group(struct task_struct *tsk)
523 {
524         struct task_cputime cputime;
525
526         thread_group_cputimer(tsk, &cputime);
527         cleanup_timers(tsk->signal->cpu_timers,
528                        cputime.utime, cputime.stime, cputime.sum_exec_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         unsigned long i;
567
568         head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?
569                 p->cpu_timers : p->signal->cpu_timers);
570         head += CPUCLOCK_WHICH(timer->it_clock);
571
572         BUG_ON(!irqs_disabled());
573         spin_lock(&p->sighand->siglock);
574
575         listpos = head;
576         if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
577                 list_for_each_entry(next, head, entry) {
578                         if (next->expires.sched > nt->expires.sched)
579                                 break;
580                         listpos = &next->entry;
581                 }
582         } else {
583                 list_for_each_entry(next, head, entry) {
584                         if (cputime_gt(next->expires.cpu, nt->expires.cpu))
585                                 break;
586                         listpos = &next->entry;
587                 }
588         }
589         list_add(&nt->entry, listpos);
590
591         if (listpos == head) {
592                 /*
593                  * We are the new earliest-expiring timer.
594                  * If we are a thread timer, there can always
595                  * be a process timer telling us to stop earlier.
596                  */
597
598                 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
599                         union cpu_time_count *exp = &nt->expires;
600
601                         switch (CPUCLOCK_WHICH(timer->it_clock)) {
602                         default:
603                                 BUG();
604                         case CPUCLOCK_PROF:
605                                 if (expires_gt(p->cputime_expires.prof_exp,
606                                                exp->cpu))
607                                         p->cputime_expires.prof_exp = exp->cpu;
608                                 break;
609                         case CPUCLOCK_VIRT:
610                                 if (expires_gt(p->cputime_expires.virt_exp,
611                                                exp->cpu))
612                                         p->cputime_expires.virt_exp = exp->cpu;
613                                 break;
614                         case CPUCLOCK_SCHED:
615                                 if (p->cputime_expires.sched_exp == 0 ||
616                                     p->cputime_expires.sched_exp > exp->sched)
617                                         p->cputime_expires.sched_exp =
618                                                                 exp->sched;
619                                 break;
620                         }
621                 } else {
622                         struct signal_struct *const sig = p->signal;
623                         union cpu_time_count *exp = &timer->it.cpu.expires;
624
625                         /*
626                          * For a process timer, set the cached expiration time.
627                          */
628                         switch (CPUCLOCK_WHICH(timer->it_clock)) {
629                         default:
630                                 BUG();
631                         case CPUCLOCK_VIRT:
632                                 if (expires_le(sig->it[CPUCLOCK_VIRT].expires,
633                                                exp->cpu))
634                                         break;
635                                 sig->cputime_expires.virt_exp = exp->cpu;
636                                 break;
637                         case CPUCLOCK_PROF:
638                                 if (expires_le(sig->it[CPUCLOCK_PROF].expires,
639                                                exp->cpu))
640                                         break;
641                                 i = sig->rlim[RLIMIT_CPU].rlim_cur;
642                                 if (i != RLIM_INFINITY &&
643                                     i <= cputime_to_secs(exp->cpu))
644                                         break;
645                                 sig->cputime_expires.prof_exp = exp->cpu;
646                                 break;
647                         case CPUCLOCK_SCHED:
648                                 sig->cputime_expires.sched_exp = exp->sched;
649                                 break;
650                         }
651                 }
652         }
653
654         spin_unlock(&p->sighand->siglock);
655 }
656
657 /*
658  * The timer is locked, fire it and arrange for its reload.
659  */
660 static void cpu_timer_fire(struct k_itimer *timer)
661 {
662         if (unlikely(timer->sigq == NULL)) {
663                 /*
664                  * This a special case for clock_nanosleep,
665                  * not a normal timer from sys_timer_create.
666                  */
667                 wake_up_process(timer->it_process);
668                 timer->it.cpu.expires.sched = 0;
669         } else if (timer->it.cpu.incr.sched == 0) {
670                 /*
671                  * One-shot timer.  Clear it as soon as it's fired.
672                  */
673                 posix_timer_event(timer, 0);
674                 timer->it.cpu.expires.sched = 0;
675         } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
676                 /*
677                  * The signal did not get queued because the signal
678                  * was ignored, so we won't get any callback to
679                  * reload the timer.  But we need to keep it
680                  * ticking in case the signal is deliverable next time.
681                  */
682                 posix_cpu_timer_schedule(timer);
683         }
684 }
685
686 /*
687  * Sample a process (thread group) timer for the given group_leader task.
688  * Must be called with tasklist_lock held for reading.
689  */
690 static int cpu_timer_sample_group(const clockid_t which_clock,
691                                   struct task_struct *p,
692                                   union cpu_time_count *cpu)
693 {
694         struct task_cputime cputime;
695
696         thread_group_cputimer(p, &cputime);
697         switch (CPUCLOCK_WHICH(which_clock)) {
698         default:
699                 return -EINVAL;
700         case CPUCLOCK_PROF:
701                 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
702                 break;
703         case CPUCLOCK_VIRT:
704                 cpu->cpu = cputime.utime;
705                 break;
706         case CPUCLOCK_SCHED:
707                 cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
708                 break;
709         }
710         return 0;
711 }
712
713 /*
714  * Guts of sys_timer_settime for CPU timers.
715  * This is called with the timer locked and interrupts disabled.
716  * If we return TIMER_RETRY, it's necessary to release the timer's lock
717  * and try again.  (This happens when the timer is in the middle of firing.)
718  */
719 int posix_cpu_timer_set(struct k_itimer *timer, int flags,
720                         struct itimerspec *new, struct itimerspec *old)
721 {
722         struct task_struct *p = timer->it.cpu.task;
723         union cpu_time_count old_expires, new_expires, val;
724         int ret;
725
726         if (unlikely(p == NULL)) {
727                 /*
728                  * Timer refers to a dead task's clock.
729                  */
730                 return -ESRCH;
731         }
732
733         new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
734
735         read_lock(&tasklist_lock);
736         /*
737          * We need the tasklist_lock to protect against reaping that
738          * clears p->signal.  If p has just been reaped, we can no
739          * longer get any information about it at all.
740          */
741         if (unlikely(p->signal == NULL)) {
742                 read_unlock(&tasklist_lock);
743                 put_task_struct(p);
744                 timer->it.cpu.task = NULL;
745                 return -ESRCH;
746         }
747
748         /*
749          * Disarm any old timer after extracting its expiry time.
750          */
751         BUG_ON(!irqs_disabled());
752
753         ret = 0;
754         spin_lock(&p->sighand->siglock);
755         old_expires = timer->it.cpu.expires;
756         if (unlikely(timer->it.cpu.firing)) {
757                 timer->it.cpu.firing = -1;
758                 ret = TIMER_RETRY;
759         } else
760                 list_del_init(&timer->it.cpu.entry);
761         spin_unlock(&p->sighand->siglock);
762
763         /*
764          * We need to sample the current value to convert the new
765          * value from to relative and absolute, and to convert the
766          * old value from absolute to relative.  To set a process
767          * timer, we need a sample to balance the thread expiry
768          * times (in arm_timer).  With an absolute time, we must
769          * check if it's already passed.  In short, we need a sample.
770          */
771         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
772                 cpu_clock_sample(timer->it_clock, p, &val);
773         } else {
774                 cpu_timer_sample_group(timer->it_clock, p, &val);
775         }
776
777         if (old) {
778                 if (old_expires.sched == 0) {
779                         old->it_value.tv_sec = 0;
780                         old->it_value.tv_nsec = 0;
781                 } else {
782                         /*
783                          * Update the timer in case it has
784                          * overrun already.  If it has,
785                          * we'll report it as having overrun
786                          * and with the next reloaded timer
787                          * already ticking, though we are
788                          * swallowing that pending
789                          * notification here to install the
790                          * new setting.
791                          */
792                         bump_cpu_timer(timer, val);
793                         if (cpu_time_before(timer->it_clock, val,
794                                             timer->it.cpu.expires)) {
795                                 old_expires = cpu_time_sub(
796                                         timer->it_clock,
797                                         timer->it.cpu.expires, val);
798                                 sample_to_timespec(timer->it_clock,
799                                                    old_expires,
800                                                    &old->it_value);
801                         } else {
802                                 old->it_value.tv_nsec = 1;
803                                 old->it_value.tv_sec = 0;
804                         }
805                 }
806         }
807
808         if (unlikely(ret)) {
809                 /*
810                  * We are colliding with the timer actually firing.
811                  * Punt after filling in the timer's old value, and
812                  * disable this firing since we are already reporting
813                  * it as an overrun (thanks to bump_cpu_timer above).
814                  */
815                 read_unlock(&tasklist_lock);
816                 goto out;
817         }
818
819         if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
820                 cpu_time_add(timer->it_clock, &new_expires, val);
821         }
822
823         /*
824          * Install the new expiry time (or zero).
825          * For a timer with no notification action, we don't actually
826          * arm the timer (we'll just fake it for timer_gettime).
827          */
828         timer->it.cpu.expires = new_expires;
829         if (new_expires.sched != 0 &&
830             (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
831             cpu_time_before(timer->it_clock, val, new_expires)) {
832                 arm_timer(timer, val);
833         }
834
835         read_unlock(&tasklist_lock);
836
837         /*
838          * Install the new reload setting, and
839          * set up the signal and overrun bookkeeping.
840          */
841         timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
842                                                 &new->it_interval);
843
844         /*
845          * This acts as a modification timestamp for the timer,
846          * so any automatic reload attempt will punt on seeing
847          * that we have reset the timer manually.
848          */
849         timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
850                 ~REQUEUE_PENDING;
851         timer->it_overrun_last = 0;
852         timer->it_overrun = -1;
853
854         if (new_expires.sched != 0 &&
855             (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
856             !cpu_time_before(timer->it_clock, val, new_expires)) {
857                 /*
858                  * The designated time already passed, so we notify
859                  * immediately, even if the thread never runs to
860                  * accumulate more time on this clock.
861                  */
862                 cpu_timer_fire(timer);
863         }
864
865         ret = 0;
866  out:
867         if (old) {
868                 sample_to_timespec(timer->it_clock,
869                                    timer->it.cpu.incr, &old->it_interval);
870         }
871         return ret;
872 }
873
874 void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
875 {
876         union cpu_time_count now;
877         struct task_struct *p = timer->it.cpu.task;
878         int clear_dead;
879
880         /*
881          * Easy part: convert the reload time.
882          */
883         sample_to_timespec(timer->it_clock,
884                            timer->it.cpu.incr, &itp->it_interval);
885
886         if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all.  */
887                 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
888                 return;
889         }
890
891         if (unlikely(p == NULL)) {
892                 /*
893                  * This task already died and the timer will never fire.
894                  * In this case, expires is actually the dead value.
895                  */
896         dead:
897                 sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
898                                    &itp->it_value);
899                 return;
900         }
901
902         /*
903          * Sample the clock to take the difference with the expiry time.
904          */
905         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
906                 cpu_clock_sample(timer->it_clock, p, &now);
907                 clear_dead = p->exit_state;
908         } else {
909                 read_lock(&tasklist_lock);
910                 if (unlikely(p->signal == NULL)) {
911                         /*
912                          * The process has been reaped.
913                          * We can't even collect a sample any more.
914                          * Call the timer disarmed, nothing else to do.
915                          */
916                         put_task_struct(p);
917                         timer->it.cpu.task = NULL;
918                         timer->it.cpu.expires.sched = 0;
919                         read_unlock(&tasklist_lock);
920                         goto dead;
921                 } else {
922                         cpu_timer_sample_group(timer->it_clock, p, &now);
923                         clear_dead = (unlikely(p->exit_state) &&
924                                       thread_group_empty(p));
925                 }
926                 read_unlock(&tasklist_lock);
927         }
928
929         if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
930                 if (timer->it.cpu.incr.sched == 0 &&
931                     cpu_time_before(timer->it_clock,
932                                     timer->it.cpu.expires, now)) {
933                         /*
934                          * Do-nothing timer expired and has no reload,
935                          * so it's as if it was never set.
936                          */
937                         timer->it.cpu.expires.sched = 0;
938                         itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
939                         return;
940                 }
941                 /*
942                  * Account for any expirations and reloads that should
943                  * have happened.
944                  */
945                 bump_cpu_timer(timer, now);
946         }
947
948         if (unlikely(clear_dead)) {
949                 /*
950                  * We've noticed that the thread is dead, but
951                  * not yet reaped.  Take this opportunity to
952                  * drop our task ref.
953                  */
954                 clear_dead_task(timer, now);
955                 goto dead;
956         }
957
958         if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
959                 sample_to_timespec(timer->it_clock,
960                                    cpu_time_sub(timer->it_clock,
961                                                 timer->it.cpu.expires, now),
962                                    &itp->it_value);
963         } else {
964                 /*
965                  * The timer should have expired already, but the firing
966                  * hasn't taken place yet.  Say it's just about to expire.
967                  */
968                 itp->it_value.tv_nsec = 1;
969                 itp->it_value.tv_sec = 0;
970         }
971 }
972
973 /*
974  * Check for any per-thread CPU timers that have fired and move them off
975  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
976  * tsk->it_*_expires values to reflect the remaining thread CPU timers.
977  */
978 static void check_thread_timers(struct task_struct *tsk,
979                                 struct list_head *firing)
980 {
981         int maxfire;
982         struct list_head *timers = tsk->cpu_timers;
983         struct signal_struct *const sig = tsk->signal;
984
985         maxfire = 20;
986         tsk->cputime_expires.prof_exp = cputime_zero;
987         while (!list_empty(timers)) {
988                 struct cpu_timer_list *t = list_first_entry(timers,
989                                                       struct cpu_timer_list,
990                                                       entry);
991                 if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
992                         tsk->cputime_expires.prof_exp = t->expires.cpu;
993                         break;
994                 }
995                 t->firing = 1;
996                 list_move_tail(&t->entry, firing);
997         }
998
999         ++timers;
1000         maxfire = 20;
1001         tsk->cputime_expires.virt_exp = cputime_zero;
1002         while (!list_empty(timers)) {
1003                 struct cpu_timer_list *t = list_first_entry(timers,
1004                                                       struct cpu_timer_list,
1005                                                       entry);
1006                 if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
1007                         tsk->cputime_expires.virt_exp = t->expires.cpu;
1008                         break;
1009                 }
1010                 t->firing = 1;
1011                 list_move_tail(&t->entry, firing);
1012         }
1013
1014         ++timers;
1015         maxfire = 20;
1016         tsk->cputime_expires.sched_exp = 0;
1017         while (!list_empty(timers)) {
1018                 struct cpu_timer_list *t = list_first_entry(timers,
1019                                                       struct cpu_timer_list,
1020                                                       entry);
1021                 if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
1022                         tsk->cputime_expires.sched_exp = t->expires.sched;
1023                         break;
1024                 }
1025                 t->firing = 1;
1026                 list_move_tail(&t->entry, firing);
1027         }
1028
1029         /*
1030          * Check for the special case thread timers.
1031          */
1032         if (sig->rlim[RLIMIT_RTTIME].rlim_cur != RLIM_INFINITY) {
1033                 unsigned long hard = sig->rlim[RLIMIT_RTTIME].rlim_max;
1034                 unsigned long *soft = &sig->rlim[RLIMIT_RTTIME].rlim_cur;
1035
1036                 if (hard != RLIM_INFINITY &&
1037                     tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
1038                         /*
1039                          * At the hard limit, we just die.
1040                          * No need to calculate anything else now.
1041                          */
1042                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1043                         return;
1044                 }
1045                 if (tsk->rt.timeout > DIV_ROUND_UP(*soft, USEC_PER_SEC/HZ)) {
1046                         /*
1047                          * At the soft limit, send a SIGXCPU every second.
1048                          */
1049                         if (sig->rlim[RLIMIT_RTTIME].rlim_cur
1050                             < sig->rlim[RLIMIT_RTTIME].rlim_max) {
1051                                 sig->rlim[RLIMIT_RTTIME].rlim_cur +=
1052                                                                 USEC_PER_SEC;
1053                         }
1054                         printk(KERN_INFO
1055                                 "RT Watchdog Timeout: %s[%d]\n",
1056                                 tsk->comm, task_pid_nr(tsk));
1057                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1058                 }
1059         }
1060 }
1061
1062 static void stop_process_timers(struct task_struct *tsk)
1063 {
1064         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
1065         unsigned long flags;
1066
1067         if (!cputimer->running)
1068                 return;
1069
1070         spin_lock_irqsave(&cputimer->lock, flags);
1071         cputimer->running = 0;
1072         spin_unlock_irqrestore(&cputimer->lock, flags);
1073 }
1074
1075 static u32 onecputick;
1076
1077 static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
1078                              cputime_t *expires, cputime_t cur_time, int signo)
1079 {
1080         if (cputime_eq(it->expires, cputime_zero))
1081                 return;
1082
1083         if (cputime_ge(cur_time, it->expires)) {
1084                 if (!cputime_eq(it->incr, cputime_zero)) {
1085                         it->expires = cputime_add(it->expires, it->incr);
1086                         it->error += it->incr_error;
1087                         if (it->error >= onecputick) {
1088                                 it->expires = cputime_sub(it->expires,
1089                                                         jiffies_to_cputime(1));
1090                                 it->error -= onecputick;
1091                         }
1092                 } else
1093                         it->expires = cputime_zero;
1094
1095                 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
1096         }
1097
1098         if (!cputime_eq(it->expires, cputime_zero) &&
1099             (cputime_eq(*expires, cputime_zero) ||
1100              cputime_lt(it->expires, *expires))) {
1101                 *expires = it->expires;
1102         }
1103 }
1104
1105 /*
1106  * Check for any per-thread CPU timers that have fired and move them
1107  * off the tsk->*_timers list onto the firing list.  Per-thread timers
1108  * have already been taken off.
1109  */
1110 static void check_process_timers(struct task_struct *tsk,
1111                                  struct list_head *firing)
1112 {
1113         int maxfire;
1114         struct signal_struct *const sig = tsk->signal;
1115         cputime_t utime, ptime, virt_expires, prof_expires;
1116         unsigned long long sum_sched_runtime, sched_expires;
1117         struct list_head *timers = sig->cpu_timers;
1118         struct task_cputime cputime;
1119
1120         /*
1121          * Don't sample the current process CPU clocks if there are no timers.
1122          */
1123         if (list_empty(&timers[CPUCLOCK_PROF]) &&
1124             cputime_eq(sig->it[CPUCLOCK_PROF].expires, cputime_zero) &&
1125             sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&
1126             list_empty(&timers[CPUCLOCK_VIRT]) &&
1127             cputime_eq(sig->it[CPUCLOCK_VIRT].expires, cputime_zero) &&
1128             list_empty(&timers[CPUCLOCK_SCHED])) {
1129                 stop_process_timers(tsk);
1130                 return;
1131         }
1132
1133         /*
1134          * Collect the current process totals.
1135          */
1136         thread_group_cputimer(tsk, &cputime);
1137         utime = cputime.utime;
1138         ptime = cputime_add(utime, cputime.stime);
1139         sum_sched_runtime = cputime.sum_exec_runtime;
1140         maxfire = 20;
1141         prof_expires = cputime_zero;
1142         while (!list_empty(timers)) {
1143                 struct cpu_timer_list *tl = list_first_entry(timers,
1144                                                       struct cpu_timer_list,
1145                                                       entry);
1146                 if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) {
1147                         prof_expires = tl->expires.cpu;
1148                         break;
1149                 }
1150                 tl->firing = 1;
1151                 list_move_tail(&tl->entry, firing);
1152         }
1153
1154         ++timers;
1155         maxfire = 20;
1156         virt_expires = cputime_zero;
1157         while (!list_empty(timers)) {
1158                 struct cpu_timer_list *tl = list_first_entry(timers,
1159                                                       struct cpu_timer_list,
1160                                                       entry);
1161                 if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) {
1162                         virt_expires = tl->expires.cpu;
1163                         break;
1164                 }
1165                 tl->firing = 1;
1166                 list_move_tail(&tl->entry, firing);
1167         }
1168
1169         ++timers;
1170         maxfire = 20;
1171         sched_expires = 0;
1172         while (!list_empty(timers)) {
1173                 struct cpu_timer_list *tl = list_first_entry(timers,
1174                                                       struct cpu_timer_list,
1175                                                       entry);
1176                 if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1177                         sched_expires = tl->expires.sched;
1178                         break;
1179                 }
1180                 tl->firing = 1;
1181                 list_move_tail(&tl->entry, firing);
1182         }
1183
1184         /*
1185          * Check for the special case process timers.
1186          */
1187         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1188                          SIGPROF);
1189         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1190                          SIGVTALRM);
1191
1192         if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
1193                 unsigned long psecs = cputime_to_secs(ptime);
1194                 cputime_t x;
1195                 if (psecs >= sig->rlim[RLIMIT_CPU].rlim_max) {
1196                         /*
1197                          * At the hard limit, we just die.
1198                          * No need to calculate anything else now.
1199                          */
1200                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1201                         return;
1202                 }
1203                 if (psecs >= sig->rlim[RLIMIT_CPU].rlim_cur) {
1204                         /*
1205                          * At the soft limit, send a SIGXCPU every second.
1206                          */
1207                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1208                         if (sig->rlim[RLIMIT_CPU].rlim_cur
1209                             < sig->rlim[RLIMIT_CPU].rlim_max) {
1210                                 sig->rlim[RLIMIT_CPU].rlim_cur++;
1211                         }
1212                 }
1213                 x = secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
1214                 if (cputime_eq(prof_expires, cputime_zero) ||
1215                     cputime_lt(x, prof_expires)) {
1216                         prof_expires = x;
1217                 }
1218         }
1219
1220         if (!cputime_eq(prof_expires, cputime_zero) &&
1221             (cputime_eq(sig->cputime_expires.prof_exp, cputime_zero) ||
1222              cputime_gt(sig->cputime_expires.prof_exp, prof_expires)))
1223                 sig->cputime_expires.prof_exp = prof_expires;
1224         if (!cputime_eq(virt_expires, cputime_zero) &&
1225             (cputime_eq(sig->cputime_expires.virt_exp, cputime_zero) ||
1226              cputime_gt(sig->cputime_expires.virt_exp, virt_expires)))
1227                 sig->cputime_expires.virt_exp = virt_expires;
1228         if (sched_expires != 0 &&
1229             (sig->cputime_expires.sched_exp == 0 ||
1230              sig->cputime_expires.sched_exp > sched_expires))
1231                 sig->cputime_expires.sched_exp = sched_expires;
1232 }
1233
1234 /*
1235  * This is called from the signal code (via do_schedule_next_timer)
1236  * when the last timer signal was delivered and we have to reload the timer.
1237  */
1238 void posix_cpu_timer_schedule(struct k_itimer *timer)
1239 {
1240         struct task_struct *p = timer->it.cpu.task;
1241         union cpu_time_count now;
1242
1243         if (unlikely(p == NULL))
1244                 /*
1245                  * The task was cleaned up already, no future firings.
1246                  */
1247                 goto out;
1248
1249         /*
1250          * Fetch the current sample and update the timer's expiry time.
1251          */
1252         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1253                 cpu_clock_sample(timer->it_clock, p, &now);
1254                 bump_cpu_timer(timer, now);
1255                 if (unlikely(p->exit_state)) {
1256                         clear_dead_task(timer, now);
1257                         goto out;
1258                 }
1259                 read_lock(&tasklist_lock); /* arm_timer needs it.  */
1260         } else {
1261                 read_lock(&tasklist_lock);
1262                 if (unlikely(p->signal == NULL)) {
1263                         /*
1264                          * The process has been reaped.
1265                          * We can't even collect a sample any more.
1266                          */
1267                         put_task_struct(p);
1268                         timer->it.cpu.task = p = NULL;
1269                         timer->it.cpu.expires.sched = 0;
1270                         goto out_unlock;
1271                 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1272                         /*
1273                          * We've noticed that the thread is dead, but
1274                          * not yet reaped.  Take this opportunity to
1275                          * drop our task ref.
1276                          */
1277                         clear_dead_task(timer, now);
1278                         goto out_unlock;
1279                 }
1280                 cpu_timer_sample_group(timer->it_clock, p, &now);
1281                 bump_cpu_timer(timer, now);
1282                 /* Leave the tasklist_lock locked for the call below.  */
1283         }
1284
1285         /*
1286          * Now re-arm for the new expiry time.
1287          */
1288         arm_timer(timer, now);
1289
1290 out_unlock:
1291         read_unlock(&tasklist_lock);
1292
1293 out:
1294         timer->it_overrun_last = timer->it_overrun;
1295         timer->it_overrun = -1;
1296         ++timer->it_requeue_pending;
1297 }
1298
1299 /**
1300  * task_cputime_zero - Check a task_cputime struct for all zero fields.
1301  *
1302  * @cputime:    The struct to compare.
1303  *
1304  * Checks @cputime to see if all fields are zero.  Returns true if all fields
1305  * are zero, false if any field is nonzero.
1306  */
1307 static inline int task_cputime_zero(const struct task_cputime *cputime)
1308 {
1309         if (cputime_eq(cputime->utime, cputime_zero) &&
1310             cputime_eq(cputime->stime, cputime_zero) &&
1311             cputime->sum_exec_runtime == 0)
1312                 return 1;
1313         return 0;
1314 }
1315
1316 /**
1317  * task_cputime_expired - Compare two task_cputime entities.
1318  *
1319  * @sample:     The task_cputime structure to be checked for expiration.
1320  * @expires:    Expiration times, against which @sample will be checked.
1321  *
1322  * Checks @sample against @expires to see if any field of @sample has expired.
1323  * Returns true if any field of the former is greater than the corresponding
1324  * field of the latter if the latter field is set.  Otherwise returns false.
1325  */
1326 static inline int task_cputime_expired(const struct task_cputime *sample,
1327                                         const struct task_cputime *expires)
1328 {
1329         if (!cputime_eq(expires->utime, cputime_zero) &&
1330             cputime_ge(sample->utime, expires->utime))
1331                 return 1;
1332         if (!cputime_eq(expires->stime, cputime_zero) &&
1333             cputime_ge(cputime_add(sample->utime, sample->stime),
1334                        expires->stime))
1335                 return 1;
1336         if (expires->sum_exec_runtime != 0 &&
1337             sample->sum_exec_runtime >= expires->sum_exec_runtime)
1338                 return 1;
1339         return 0;
1340 }
1341
1342 /**
1343  * fastpath_timer_check - POSIX CPU timers fast path.
1344  *
1345  * @tsk:        The task (thread) being checked.
1346  *
1347  * Check the task and thread group timers.  If both are zero (there are no
1348  * timers set) return false.  Otherwise snapshot the task and thread group
1349  * timers and compare them with the corresponding expiration times.  Return
1350  * true if a timer has expired, else return false.
1351  */
1352 static inline int fastpath_timer_check(struct task_struct *tsk)
1353 {
1354         struct signal_struct *sig;
1355
1356         /* tsk == current, ensure it is safe to use ->signal/sighand */
1357         if (unlikely(tsk->exit_state))
1358                 return 0;
1359
1360         if (!task_cputime_zero(&tsk->cputime_expires)) {
1361                 struct task_cputime task_sample = {
1362                         .utime = tsk->utime,
1363                         .stime = tsk->stime,
1364                         .sum_exec_runtime = tsk->se.sum_exec_runtime
1365                 };
1366
1367                 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1368                         return 1;
1369         }
1370
1371         sig = tsk->signal;
1372         if (!task_cputime_zero(&sig->cputime_expires)) {
1373                 struct task_cputime group_sample;
1374
1375                 thread_group_cputimer(tsk, &group_sample);
1376                 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1377                         return 1;
1378         }
1379
1380         return sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY;
1381 }
1382
1383 /*
1384  * This is called from the timer interrupt handler.  The irq handler has
1385  * already updated our counts.  We need to check if any timers fire now.
1386  * Interrupts are disabled.
1387  */
1388 void run_posix_cpu_timers(struct task_struct *tsk)
1389 {
1390         LIST_HEAD(firing);
1391         struct k_itimer *timer, *next;
1392
1393         BUG_ON(!irqs_disabled());
1394
1395         /*
1396          * The fast path checks that there are no expired thread or thread
1397          * group timers.  If that's so, just return.
1398          */
1399         if (!fastpath_timer_check(tsk))
1400                 return;
1401
1402         spin_lock(&tsk->sighand->siglock);
1403         /*
1404          * Here we take off tsk->signal->cpu_timers[N] and
1405          * tsk->cpu_timers[N] all the timers that are firing, and
1406          * put them on the firing list.
1407          */
1408         check_thread_timers(tsk, &firing);
1409         check_process_timers(tsk, &firing);
1410
1411         /*
1412          * We must release these locks before taking any timer's lock.
1413          * There is a potential race with timer deletion here, as the
1414          * siglock now protects our private firing list.  We have set
1415          * the firing flag in each timer, so that a deletion attempt
1416          * that gets the timer lock before we do will give it up and
1417          * spin until we've taken care of that timer below.
1418          */
1419         spin_unlock(&tsk->sighand->siglock);
1420
1421         /*
1422          * Now that all the timers on our list have the firing flag,
1423          * noone will touch their list entries but us.  We'll take
1424          * each timer's lock before clearing its firing flag, so no
1425          * timer call will interfere.
1426          */
1427         list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1428                 int cpu_firing;
1429
1430                 spin_lock(&timer->it_lock);
1431                 list_del_init(&timer->it.cpu.entry);
1432                 cpu_firing = timer->it.cpu.firing;
1433                 timer->it.cpu.firing = 0;
1434                 /*
1435                  * The firing flag is -1 if we collided with a reset
1436                  * of the timer, which already reported this
1437                  * almost-firing as an overrun.  So don't generate an event.
1438                  */
1439                 if (likely(cpu_firing >= 0))
1440                         cpu_timer_fire(timer);
1441                 spin_unlock(&timer->it_lock);
1442         }
1443 }
1444
1445 /*
1446  * Set one of the process-wide special case CPU timers.
1447  * The tsk->sighand->siglock must be held by the caller.
1448  * The *newval argument is relative and we update it to be absolute, *oldval
1449  * is absolute and we update it to be relative.
1450  */
1451 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1452                            cputime_t *newval, cputime_t *oldval)
1453 {
1454         union cpu_time_count now;
1455         struct list_head *head;
1456
1457         BUG_ON(clock_idx == CPUCLOCK_SCHED);
1458         cpu_timer_sample_group(clock_idx, tsk, &now);
1459
1460         if (oldval) {
1461                 if (!cputime_eq(*oldval, cputime_zero)) {
1462                         if (cputime_le(*oldval, now.cpu)) {
1463                                 /* Just about to fire. */
1464                                 *oldval = jiffies_to_cputime(1);
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                  * If the RLIMIT_CPU timer will expire before the
1476                  * ITIMER_PROF timer, we have nothing else to do.
1477                  */
1478                 if (tsk->signal->rlim[RLIMIT_CPU].rlim_cur
1479                     < cputime_to_secs(*newval))
1480                         return;
1481         }
1482
1483         /*
1484          * Check whether there are any process timers already set to fire
1485          * before this one.  If so, we don't have anything more to do.
1486          */
1487         head = &tsk->signal->cpu_timers[clock_idx];
1488         if (list_empty(head) ||
1489             cputime_ge(list_first_entry(head,
1490                                   struct cpu_timer_list, entry)->expires.cpu,
1491                        *newval)) {
1492                 switch (clock_idx) {
1493                 case CPUCLOCK_PROF:
1494                         tsk->signal->cputime_expires.prof_exp = *newval;
1495                         break;
1496                 case CPUCLOCK_VIRT:
1497                         tsk->signal->cputime_expires.virt_exp = *newval;
1498                         break;
1499                 }
1500         }
1501 }
1502
1503 static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1504                             struct timespec *rqtp, struct itimerspec *it)
1505 {
1506         struct k_itimer timer;
1507         int error;
1508
1509         /*
1510          * Set up a temporary timer and then wait for it to go off.
1511          */
1512         memset(&timer, 0, sizeof timer);
1513         spin_lock_init(&timer.it_lock);
1514         timer.it_clock = which_clock;
1515         timer.it_overrun = -1;
1516         error = posix_cpu_timer_create(&timer);
1517         timer.it_process = current;
1518         if (!error) {
1519                 static struct itimerspec zero_it;
1520
1521                 memset(it, 0, sizeof *it);
1522                 it->it_value = *rqtp;
1523
1524                 spin_lock_irq(&timer.it_lock);
1525                 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1526                 if (error) {
1527                         spin_unlock_irq(&timer.it_lock);
1528                         return error;
1529                 }
1530
1531                 while (!signal_pending(current)) {
1532                         if (timer.it.cpu.expires.sched == 0) {
1533                                 /*
1534                                  * Our timer fired and was reset.
1535                                  */
1536                                 spin_unlock_irq(&timer.it_lock);
1537                                 return 0;
1538                         }
1539
1540                         /*
1541                          * Block until cpu_timer_fire (or a signal) wakes us.
1542                          */
1543                         __set_current_state(TASK_INTERRUPTIBLE);
1544                         spin_unlock_irq(&timer.it_lock);
1545                         schedule();
1546                         spin_lock_irq(&timer.it_lock);
1547                 }
1548
1549                 /*
1550                  * We were interrupted by a signal.
1551                  */
1552                 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1553                 posix_cpu_timer_set(&timer, 0, &zero_it, it);
1554                 spin_unlock_irq(&timer.it_lock);
1555
1556                 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1557                         /*
1558                          * It actually did fire already.
1559                          */
1560                         return 0;
1561                 }
1562
1563                 error = -ERESTART_RESTARTBLOCK;
1564         }
1565
1566         return error;
1567 }
1568
1569 int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1570                      struct timespec *rqtp, struct timespec __user *rmtp)
1571 {
1572         struct restart_block *restart_block =
1573             &current_thread_info()->restart_block;
1574         struct itimerspec it;
1575         int error;
1576
1577         /*
1578          * Diagnose required errors first.
1579          */
1580         if (CPUCLOCK_PERTHREAD(which_clock) &&
1581             (CPUCLOCK_PID(which_clock) == 0 ||
1582              CPUCLOCK_PID(which_clock) == current->pid))
1583                 return -EINVAL;
1584
1585         error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1586
1587         if (error == -ERESTART_RESTARTBLOCK) {
1588
1589                 if (flags & TIMER_ABSTIME)
1590                         return -ERESTARTNOHAND;
1591                 /*
1592                  * Report back to the user the time still remaining.
1593                  */
1594                 if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1595                         return -EFAULT;
1596
1597                 restart_block->fn = posix_cpu_nsleep_restart;
1598                 restart_block->arg0 = which_clock;
1599                 restart_block->arg1 = (unsigned long) rmtp;
1600                 restart_block->arg2 = rqtp->tv_sec;
1601                 restart_block->arg3 = rqtp->tv_nsec;
1602         }
1603         return error;
1604 }
1605
1606 long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1607 {
1608         clockid_t which_clock = restart_block->arg0;
1609         struct timespec __user *rmtp;
1610         struct timespec t;
1611         struct itimerspec it;
1612         int error;
1613
1614         rmtp = (struct timespec __user *) restart_block->arg1;
1615         t.tv_sec = restart_block->arg2;
1616         t.tv_nsec = restart_block->arg3;
1617
1618         restart_block->fn = do_no_restart_syscall;
1619         error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1620
1621         if (error == -ERESTART_RESTARTBLOCK) {
1622                 /*
1623                  * Report back to the user the time still remaining.
1624                  */
1625                 if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1626                         return -EFAULT;
1627
1628                 restart_block->fn = posix_cpu_nsleep_restart;
1629                 restart_block->arg0 = which_clock;
1630                 restart_block->arg1 = (unsigned long) rmtp;
1631                 restart_block->arg2 = t.tv_sec;
1632                 restart_block->arg3 = t.tv_nsec;
1633         }
1634         return error;
1635
1636 }
1637
1638
1639 #define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1640 #define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1641
1642 static int process_cpu_clock_getres(const clockid_t which_clock,
1643                                     struct timespec *tp)
1644 {
1645         return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1646 }
1647 static int process_cpu_clock_get(const clockid_t which_clock,
1648                                  struct timespec *tp)
1649 {
1650         return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1651 }
1652 static int process_cpu_timer_create(struct k_itimer *timer)
1653 {
1654         timer->it_clock = PROCESS_CLOCK;
1655         return posix_cpu_timer_create(timer);
1656 }
1657 static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1658                               struct timespec *rqtp,
1659                               struct timespec __user *rmtp)
1660 {
1661         return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1662 }
1663 static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1664 {
1665         return -EINVAL;
1666 }
1667 static int thread_cpu_clock_getres(const clockid_t which_clock,
1668                                    struct timespec *tp)
1669 {
1670         return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1671 }
1672 static int thread_cpu_clock_get(const clockid_t which_clock,
1673                                 struct timespec *tp)
1674 {
1675         return posix_cpu_clock_get(THREAD_CLOCK, tp);
1676 }
1677 static int thread_cpu_timer_create(struct k_itimer *timer)
1678 {
1679         timer->it_clock = THREAD_CLOCK;
1680         return posix_cpu_timer_create(timer);
1681 }
1682 static int thread_cpu_nsleep(const clockid_t which_clock, int flags,
1683                               struct timespec *rqtp, struct timespec __user *rmtp)
1684 {
1685         return -EINVAL;
1686 }
1687 static long thread_cpu_nsleep_restart(struct restart_block *restart_block)
1688 {
1689         return -EINVAL;
1690 }
1691
1692 static __init int init_posix_cpu_timers(void)
1693 {
1694         struct k_clock process = {
1695                 .clock_getres = process_cpu_clock_getres,
1696                 .clock_get = process_cpu_clock_get,
1697                 .clock_set = do_posix_clock_nosettime,
1698                 .timer_create = process_cpu_timer_create,
1699                 .nsleep = process_cpu_nsleep,
1700                 .nsleep_restart = process_cpu_nsleep_restart,
1701         };
1702         struct k_clock thread = {
1703                 .clock_getres = thread_cpu_clock_getres,
1704                 .clock_get = thread_cpu_clock_get,
1705                 .clock_set = do_posix_clock_nosettime,
1706                 .timer_create = thread_cpu_timer_create,
1707                 .nsleep = thread_cpu_nsleep,
1708                 .nsleep_restart = thread_cpu_nsleep_restart,
1709         };
1710         struct timespec ts;
1711
1712         register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1713         register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1714
1715         cputime_to_timespec(jiffies_to_cputime(1), &ts);
1716         onecputick = ts.tv_nsec;
1717         WARN_ON(ts.tv_sec != 0);
1718
1719         return 0;
1720 }
1721 __initcall(init_posix_cpu_timers);