ore: Make ore_striping_info and ore_calc_stripe_info public
[linux-2.6.git] / kernel / posix-cpu-timers.c
1 /*
2  * Implement CPU time clocks for the POSIX clock interface.
3  */
4
5 #include <linux/sched.h>
6 #include <linux/posix-timers.h>
7 #include <linux/errno.h>
8 #include <linux/math64.h>
9 #include <asm/uaccess.h>
10 #include <linux/kernel_stat.h>
11 #include <trace/events/timer.h>
12
13 /*
14  * Called after updating RLIMIT_CPU to run cpu timer and update
15  * tsk->signal->cputime_expires expiration cache if necessary. Needs
16  * siglock protection since other code may update expiration cache as
17  * well.
18  */
19 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
20 {
21         cputime_t cputime = secs_to_cputime(rlim_new);
22
23         spin_lock_irq(&task->sighand->siglock);
24         set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
25         spin_unlock_irq(&task->sighand->siglock);
26 }
27
28 static int check_clock(const clockid_t which_clock)
29 {
30         int error = 0;
31         struct task_struct *p;
32         const pid_t pid = CPUCLOCK_PID(which_clock);
33
34         if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
35                 return -EINVAL;
36
37         if (pid == 0)
38                 return 0;
39
40         rcu_read_lock();
41         p = find_task_by_vpid(pid);
42         if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
43                    same_thread_group(p, current) : has_group_leader_pid(p))) {
44                 error = -EINVAL;
45         }
46         rcu_read_unlock();
47
48         return error;
49 }
50
51 static inline union cpu_time_count
52 timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
53 {
54         union cpu_time_count ret;
55         ret.sched = 0;          /* high half always zero when .cpu used */
56         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
57                 ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
58         } else {
59                 ret.cpu = timespec_to_cputime(tp);
60         }
61         return ret;
62 }
63
64 static void sample_to_timespec(const clockid_t which_clock,
65                                union cpu_time_count cpu,
66                                struct timespec *tp)
67 {
68         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED)
69                 *tp = ns_to_timespec(cpu.sched);
70         else
71                 cputime_to_timespec(cpu.cpu, tp);
72 }
73
74 static inline int cpu_time_before(const clockid_t which_clock,
75                                   union cpu_time_count now,
76                                   union cpu_time_count then)
77 {
78         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
79                 return now.sched < then.sched;
80         }  else {
81                 return cputime_lt(now.cpu, then.cpu);
82         }
83 }
84 static inline void cpu_time_add(const clockid_t which_clock,
85                                 union cpu_time_count *acc,
86                                 union cpu_time_count val)
87 {
88         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
89                 acc->sched += val.sched;
90         }  else {
91                 acc->cpu = cputime_add(acc->cpu, val.cpu);
92         }
93 }
94 static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
95                                                 union cpu_time_count a,
96                                                 union cpu_time_count b)
97 {
98         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
99                 a.sched -= b.sched;
100         }  else {
101                 a.cpu = cputime_sub(a.cpu, b.cpu);
102         }
103         return a;
104 }
105
106 /*
107  * Divide and limit the result to res >= 1
108  *
109  * This is necessary to prevent signal delivery starvation, when the result of
110  * the division would be rounded down to 0.
111  */
112 static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
113 {
114         cputime_t res = cputime_div(time, div);
115
116         return max_t(cputime_t, res, 1);
117 }
118
119 /*
120  * Update expiry time from increment, and increase overrun count,
121  * given the current clock sample.
122  */
123 static void bump_cpu_timer(struct k_itimer *timer,
124                                   union cpu_time_count now)
125 {
126         int i;
127
128         if (timer->it.cpu.incr.sched == 0)
129                 return;
130
131         if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
132                 unsigned long long delta, incr;
133
134                 if (now.sched < timer->it.cpu.expires.sched)
135                         return;
136                 incr = timer->it.cpu.incr.sched;
137                 delta = now.sched + incr - timer->it.cpu.expires.sched;
138                 /* Don't use (incr*2 < delta), incr*2 might overflow. */
139                 for (i = 0; incr < delta - incr; i++)
140                         incr = incr << 1;
141                 for (; i >= 0; incr >>= 1, i--) {
142                         if (delta < incr)
143                                 continue;
144                         timer->it.cpu.expires.sched += incr;
145                         timer->it_overrun += 1 << i;
146                         delta -= incr;
147                 }
148         } else {
149                 cputime_t delta, incr;
150
151                 if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu))
152                         return;
153                 incr = timer->it.cpu.incr.cpu;
154                 delta = cputime_sub(cputime_add(now.cpu, incr),
155                                     timer->it.cpu.expires.cpu);
156                 /* Don't use (incr*2 < delta), incr*2 might overflow. */
157                 for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
158                              incr = cputime_add(incr, incr);
159                 for (; i >= 0; incr = cputime_halve(incr), i--) {
160                         if (cputime_lt(delta, incr))
161                                 continue;
162                         timer->it.cpu.expires.cpu =
163                                 cputime_add(timer->it.cpu.expires.cpu, incr);
164                         timer->it_overrun += 1 << i;
165                         delta = cputime_sub(delta, incr);
166                 }
167         }
168 }
169
170 static inline cputime_t prof_ticks(struct task_struct *p)
171 {
172         return cputime_add(p->utime, p->stime);
173 }
174 static inline cputime_t virt_ticks(struct task_struct *p)
175 {
176         return p->utime;
177 }
178
179 static int
180 posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
181 {
182         int error = check_clock(which_clock);
183         if (!error) {
184                 tp->tv_sec = 0;
185                 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
186                 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
187                         /*
188                          * If sched_clock is using a cycle counter, we
189                          * don't have any idea of its true resolution
190                          * exported, but it is much more than 1s/HZ.
191                          */
192                         tp->tv_nsec = 1;
193                 }
194         }
195         return error;
196 }
197
198 static int
199 posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
200 {
201         /*
202          * You can never reset a CPU clock, but we check for other errors
203          * in the call before failing with EPERM.
204          */
205         int error = check_clock(which_clock);
206         if (error == 0) {
207                 error = -EPERM;
208         }
209         return error;
210 }
211
212
213 /*
214  * Sample a per-thread clock for the given task.
215  */
216 static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
217                             union cpu_time_count *cpu)
218 {
219         switch (CPUCLOCK_WHICH(which_clock)) {
220         default:
221                 return -EINVAL;
222         case CPUCLOCK_PROF:
223                 cpu->cpu = prof_ticks(p);
224                 break;
225         case CPUCLOCK_VIRT:
226                 cpu->cpu = virt_ticks(p);
227                 break;
228         case CPUCLOCK_SCHED:
229                 cpu->sched = task_sched_runtime(p);
230                 break;
231         }
232         return 0;
233 }
234
235 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
236 {
237         struct signal_struct *sig = tsk->signal;
238         struct task_struct *t;
239
240         times->utime = sig->utime;
241         times->stime = sig->stime;
242         times->sum_exec_runtime = sig->sum_sched_runtime;
243
244         rcu_read_lock();
245         /* make sure we can trust tsk->thread_group list */
246         if (!likely(pid_alive(tsk)))
247                 goto out;
248
249         t = tsk;
250         do {
251                 times->utime = cputime_add(times->utime, t->utime);
252                 times->stime = cputime_add(times->stime, t->stime);
253                 times->sum_exec_runtime += t->se.sum_exec_runtime;
254         } while_each_thread(tsk, t);
255 out:
256         rcu_read_unlock();
257 }
258
259 static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
260 {
261         if (cputime_gt(b->utime, a->utime))
262                 a->utime = b->utime;
263
264         if (cputime_gt(b->stime, a->stime))
265                 a->stime = b->stime;
266
267         if (b->sum_exec_runtime > a->sum_exec_runtime)
268                 a->sum_exec_runtime = b->sum_exec_runtime;
269 }
270
271 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
272 {
273         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
274         struct task_cputime sum;
275         unsigned long flags;
276
277         spin_lock_irqsave(&cputimer->lock, flags);
278         if (!cputimer->running) {
279                 cputimer->running = 1;
280                 /*
281                  * The POSIX timer interface allows for absolute time expiry
282                  * values through the TIMER_ABSTIME flag, therefore we have
283                  * to synchronize the timer to the clock every time we start
284                  * it.
285                  */
286                 thread_group_cputime(tsk, &sum);
287                 update_gt_cputime(&cputimer->cputime, &sum);
288         }
289         *times = cputimer->cputime;
290         spin_unlock_irqrestore(&cputimer->lock, flags);
291 }
292
293 /*
294  * Sample a process (thread group) clock for the given group_leader task.
295  * Must be called with tasklist_lock held for reading.
296  */
297 static int cpu_clock_sample_group(const clockid_t which_clock,
298                                   struct task_struct *p,
299                                   union cpu_time_count *cpu)
300 {
301         struct task_cputime cputime;
302
303         switch (CPUCLOCK_WHICH(which_clock)) {
304         default:
305                 return -EINVAL;
306         case CPUCLOCK_PROF:
307                 thread_group_cputime(p, &cputime);
308                 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
309                 break;
310         case CPUCLOCK_VIRT:
311                 thread_group_cputime(p, &cputime);
312                 cpu->cpu = cputime.utime;
313                 break;
314         case CPUCLOCK_SCHED:
315                 cpu->sched = thread_group_sched_runtime(p);
316                 break;
317         }
318         return 0;
319 }
320
321
322 static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
323 {
324         const pid_t pid = CPUCLOCK_PID(which_clock);
325         int error = -EINVAL;
326         union cpu_time_count rtn;
327
328         if (pid == 0) {
329                 /*
330                  * Special case constant value for our own clocks.
331                  * We don't have to do any lookup to find ourselves.
332                  */
333                 if (CPUCLOCK_PERTHREAD(which_clock)) {
334                         /*
335                          * Sampling just ourselves we can do with no locking.
336                          */
337                         error = cpu_clock_sample(which_clock,
338                                                  current, &rtn);
339                 } else {
340                         read_lock(&tasklist_lock);
341                         error = cpu_clock_sample_group(which_clock,
342                                                        current, &rtn);
343                         read_unlock(&tasklist_lock);
344                 }
345         } else {
346                 /*
347                  * Find the given PID, and validate that the caller
348                  * should be able to see it.
349                  */
350                 struct task_struct *p;
351                 rcu_read_lock();
352                 p = find_task_by_vpid(pid);
353                 if (p) {
354                         if (CPUCLOCK_PERTHREAD(which_clock)) {
355                                 if (same_thread_group(p, current)) {
356                                         error = cpu_clock_sample(which_clock,
357                                                                  p, &rtn);
358                                 }
359                         } else {
360                                 read_lock(&tasklist_lock);
361                                 if (thread_group_leader(p) && p->sighand) {
362                                         error =
363                                             cpu_clock_sample_group(which_clock,
364                                                                    p, &rtn);
365                                 }
366                                 read_unlock(&tasklist_lock);
367                         }
368                 }
369                 rcu_read_unlock();
370         }
371
372         if (error)
373                 return error;
374         sample_to_timespec(which_clock, rtn, tp);
375         return 0;
376 }
377
378
379 /*
380  * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
381  * This is called from sys_timer_create() and do_cpu_nanosleep() with the
382  * new timer already all-zeros initialized.
383  */
384 static int posix_cpu_timer_create(struct k_itimer *new_timer)
385 {
386         int ret = 0;
387         const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
388         struct task_struct *p;
389
390         if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
391                 return -EINVAL;
392
393         INIT_LIST_HEAD(&new_timer->it.cpu.entry);
394
395         rcu_read_lock();
396         if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
397                 if (pid == 0) {
398                         p = current;
399                 } else {
400                         p = find_task_by_vpid(pid);
401                         if (p && !same_thread_group(p, current))
402                                 p = NULL;
403                 }
404         } else {
405                 if (pid == 0) {
406                         p = current->group_leader;
407                 } else {
408                         p = find_task_by_vpid(pid);
409                         if (p && !has_group_leader_pid(p))
410                                 p = NULL;
411                 }
412         }
413         new_timer->it.cpu.task = p;
414         if (p) {
415                 get_task_struct(p);
416         } else {
417                 ret = -EINVAL;
418         }
419         rcu_read_unlock();
420
421         return ret;
422 }
423
424 /*
425  * Clean up a CPU-clock timer that is about to be destroyed.
426  * This is called from timer deletion with the timer already locked.
427  * If we return TIMER_RETRY, it's necessary to release the timer's lock
428  * and try again.  (This happens when the timer is in the middle of firing.)
429  */
430 static int posix_cpu_timer_del(struct k_itimer *timer)
431 {
432         struct task_struct *p = timer->it.cpu.task;
433         int ret = 0;
434
435         if (likely(p != NULL)) {
436                 read_lock(&tasklist_lock);
437                 if (unlikely(p->sighand == NULL)) {
438                         /*
439                          * We raced with the reaping of the task.
440                          * The deletion should have cleared us off the list.
441                          */
442                         BUG_ON(!list_empty(&timer->it.cpu.entry));
443                 } else {
444                         spin_lock(&p->sighand->siglock);
445                         if (timer->it.cpu.firing)
446                                 ret = TIMER_RETRY;
447                         else
448                                 list_del(&timer->it.cpu.entry);
449                         spin_unlock(&p->sighand->siglock);
450                 }
451                 read_unlock(&tasklist_lock);
452
453                 if (!ret)
454                         put_task_struct(p);
455         }
456
457         return ret;
458 }
459
460 /*
461  * Clean out CPU timers still ticking when a thread exited.  The task
462  * pointer is cleared, and the expiry time is replaced with the residual
463  * time for later timer_gettime calls to return.
464  * This must be called with the siglock held.
465  */
466 static void cleanup_timers(struct list_head *head,
467                            cputime_t utime, cputime_t stime,
468                            unsigned long long sum_exec_runtime)
469 {
470         struct cpu_timer_list *timer, *next;
471         cputime_t ptime = cputime_add(utime, stime);
472
473         list_for_each_entry_safe(timer, next, head, entry) {
474                 list_del_init(&timer->entry);
475                 if (cputime_lt(timer->expires.cpu, ptime)) {
476                         timer->expires.cpu = cputime_zero;
477                 } else {
478                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
479                                                          ptime);
480                 }
481         }
482
483         ++head;
484         list_for_each_entry_safe(timer, next, head, entry) {
485                 list_del_init(&timer->entry);
486                 if (cputime_lt(timer->expires.cpu, utime)) {
487                         timer->expires.cpu = cputime_zero;
488                 } else {
489                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
490                                                          utime);
491                 }
492         }
493
494         ++head;
495         list_for_each_entry_safe(timer, next, head, entry) {
496                 list_del_init(&timer->entry);
497                 if (timer->expires.sched < sum_exec_runtime) {
498                         timer->expires.sched = 0;
499                 } else {
500                         timer->expires.sched -= sum_exec_runtime;
501                 }
502         }
503 }
504
505 /*
506  * These are both called with the siglock held, when the current thread
507  * is being reaped.  When the final (leader) thread in the group is reaped,
508  * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
509  */
510 void posix_cpu_timers_exit(struct task_struct *tsk)
511 {
512         cleanup_timers(tsk->cpu_timers,
513                        tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
514
515 }
516 void posix_cpu_timers_exit_group(struct task_struct *tsk)
517 {
518         struct signal_struct *const sig = tsk->signal;
519
520         cleanup_timers(tsk->signal->cpu_timers,
521                        cputime_add(tsk->utime, sig->utime),
522                        cputime_add(tsk->stime, sig->stime),
523                        tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
524 }
525
526 static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
527 {
528         /*
529          * That's all for this thread or process.
530          * We leave our residual in expires to be reported.
531          */
532         put_task_struct(timer->it.cpu.task);
533         timer->it.cpu.task = NULL;
534         timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
535                                              timer->it.cpu.expires,
536                                              now);
537 }
538
539 static inline int expires_gt(cputime_t expires, cputime_t new_exp)
540 {
541         return cputime_eq(expires, cputime_zero) ||
542                cputime_gt(expires, new_exp);
543 }
544
545 /*
546  * Insert the timer on the appropriate list before any timers that
547  * expire later.  This must be called with the tasklist_lock held
548  * for reading, interrupts disabled and p->sighand->siglock taken.
549  */
550 static void arm_timer(struct k_itimer *timer)
551 {
552         struct task_struct *p = timer->it.cpu.task;
553         struct list_head *head, *listpos;
554         struct task_cputime *cputime_expires;
555         struct cpu_timer_list *const nt = &timer->it.cpu;
556         struct cpu_timer_list *next;
557
558         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
559                 head = p->cpu_timers;
560                 cputime_expires = &p->cputime_expires;
561         } else {
562                 head = p->signal->cpu_timers;
563                 cputime_expires = &p->signal->cputime_expires;
564         }
565         head += CPUCLOCK_WHICH(timer->it_clock);
566
567         listpos = head;
568         list_for_each_entry(next, head, entry) {
569                 if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
570                         break;
571                 listpos = &next->entry;
572         }
573         list_add(&nt->entry, listpos);
574
575         if (listpos == head) {
576                 union cpu_time_count *exp = &nt->expires;
577
578                 /*
579                  * We are the new earliest-expiring POSIX 1.b timer, hence
580                  * need to update expiration cache. Take into account that
581                  * for process timers we share expiration cache with itimers
582                  * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
583                  */
584
585                 switch (CPUCLOCK_WHICH(timer->it_clock)) {
586                 case CPUCLOCK_PROF:
587                         if (expires_gt(cputime_expires->prof_exp, exp->cpu))
588                                 cputime_expires->prof_exp = exp->cpu;
589                         break;
590                 case CPUCLOCK_VIRT:
591                         if (expires_gt(cputime_expires->virt_exp, exp->cpu))
592                                 cputime_expires->virt_exp = exp->cpu;
593                         break;
594                 case CPUCLOCK_SCHED:
595                         if (cputime_expires->sched_exp == 0 ||
596                             cputime_expires->sched_exp > exp->sched)
597                                 cputime_expires->sched_exp = exp->sched;
598                         break;
599                 }
600         }
601 }
602
603 /*
604  * The timer is locked, fire it and arrange for its reload.
605  */
606 static void cpu_timer_fire(struct k_itimer *timer)
607 {
608         if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
609                 /*
610                  * User don't want any signal.
611                  */
612                 timer->it.cpu.expires.sched = 0;
613         } else if (unlikely(timer->sigq == NULL)) {
614                 /*
615                  * This a special case for clock_nanosleep,
616                  * not a normal timer from sys_timer_create.
617                  */
618                 wake_up_process(timer->it_process);
619                 timer->it.cpu.expires.sched = 0;
620         } else if (timer->it.cpu.incr.sched == 0) {
621                 /*
622                  * One-shot timer.  Clear it as soon as it's fired.
623                  */
624                 posix_timer_event(timer, 0);
625                 timer->it.cpu.expires.sched = 0;
626         } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
627                 /*
628                  * The signal did not get queued because the signal
629                  * was ignored, so we won't get any callback to
630                  * reload the timer.  But we need to keep it
631                  * ticking in case the signal is deliverable next time.
632                  */
633                 posix_cpu_timer_schedule(timer);
634         }
635 }
636
637 /*
638  * Sample a process (thread group) timer for the given group_leader task.
639  * Must be called with tasklist_lock held for reading.
640  */
641 static int cpu_timer_sample_group(const clockid_t which_clock,
642                                   struct task_struct *p,
643                                   union cpu_time_count *cpu)
644 {
645         struct task_cputime cputime;
646
647         thread_group_cputimer(p, &cputime);
648         switch (CPUCLOCK_WHICH(which_clock)) {
649         default:
650                 return -EINVAL;
651         case CPUCLOCK_PROF:
652                 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
653                 break;
654         case CPUCLOCK_VIRT:
655                 cpu->cpu = cputime.utime;
656                 break;
657         case CPUCLOCK_SCHED:
658                 cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
659                 break;
660         }
661         return 0;
662 }
663
664 /*
665  * Guts of sys_timer_settime for CPU timers.
666  * This is called with the timer locked and interrupts disabled.
667  * If we return TIMER_RETRY, it's necessary to release the timer's lock
668  * and try again.  (This happens when the timer is in the middle of firing.)
669  */
670 static int posix_cpu_timer_set(struct k_itimer *timer, int flags,
671                                struct itimerspec *new, struct itimerspec *old)
672 {
673         struct task_struct *p = timer->it.cpu.task;
674         union cpu_time_count old_expires, new_expires, old_incr, val;
675         int ret;
676
677         if (unlikely(p == NULL)) {
678                 /*
679                  * Timer refers to a dead task's clock.
680                  */
681                 return -ESRCH;
682         }
683
684         new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
685
686         read_lock(&tasklist_lock);
687         /*
688          * We need the tasklist_lock to protect against reaping that
689          * clears p->sighand.  If p has just been reaped, we can no
690          * longer get any information about it at all.
691          */
692         if (unlikely(p->sighand == NULL)) {
693                 read_unlock(&tasklist_lock);
694                 put_task_struct(p);
695                 timer->it.cpu.task = NULL;
696                 return -ESRCH;
697         }
698
699         /*
700          * Disarm any old timer after extracting its expiry time.
701          */
702         BUG_ON(!irqs_disabled());
703
704         ret = 0;
705         old_incr = timer->it.cpu.incr;
706         spin_lock(&p->sighand->siglock);
707         old_expires = timer->it.cpu.expires;
708         if (unlikely(timer->it.cpu.firing)) {
709                 timer->it.cpu.firing = -1;
710                 ret = TIMER_RETRY;
711         } else
712                 list_del_init(&timer->it.cpu.entry);
713
714         /*
715          * We need to sample the current value to convert the new
716          * value from to relative and absolute, and to convert the
717          * old value from absolute to relative.  To set a process
718          * timer, we need a sample to balance the thread expiry
719          * times (in arm_timer).  With an absolute time, we must
720          * check if it's already passed.  In short, we need a sample.
721          */
722         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
723                 cpu_clock_sample(timer->it_clock, p, &val);
724         } else {
725                 cpu_timer_sample_group(timer->it_clock, p, &val);
726         }
727
728         if (old) {
729                 if (old_expires.sched == 0) {
730                         old->it_value.tv_sec = 0;
731                         old->it_value.tv_nsec = 0;
732                 } else {
733                         /*
734                          * Update the timer in case it has
735                          * overrun already.  If it has,
736                          * we'll report it as having overrun
737                          * and with the next reloaded timer
738                          * already ticking, though we are
739                          * swallowing that pending
740                          * notification here to install the
741                          * new setting.
742                          */
743                         bump_cpu_timer(timer, val);
744                         if (cpu_time_before(timer->it_clock, val,
745                                             timer->it.cpu.expires)) {
746                                 old_expires = cpu_time_sub(
747                                         timer->it_clock,
748                                         timer->it.cpu.expires, val);
749                                 sample_to_timespec(timer->it_clock,
750                                                    old_expires,
751                                                    &old->it_value);
752                         } else {
753                                 old->it_value.tv_nsec = 1;
754                                 old->it_value.tv_sec = 0;
755                         }
756                 }
757         }
758
759         if (unlikely(ret)) {
760                 /*
761                  * We are colliding with the timer actually firing.
762                  * Punt after filling in the timer's old value, and
763                  * disable this firing since we are already reporting
764                  * it as an overrun (thanks to bump_cpu_timer above).
765                  */
766                 spin_unlock(&p->sighand->siglock);
767                 read_unlock(&tasklist_lock);
768                 goto out;
769         }
770
771         if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
772                 cpu_time_add(timer->it_clock, &new_expires, val);
773         }
774
775         /*
776          * Install the new expiry time (or zero).
777          * For a timer with no notification action, we don't actually
778          * arm the timer (we'll just fake it for timer_gettime).
779          */
780         timer->it.cpu.expires = new_expires;
781         if (new_expires.sched != 0 &&
782             cpu_time_before(timer->it_clock, val, new_expires)) {
783                 arm_timer(timer);
784         }
785
786         spin_unlock(&p->sighand->siglock);
787         read_unlock(&tasklist_lock);
788
789         /*
790          * Install the new reload setting, and
791          * set up the signal and overrun bookkeeping.
792          */
793         timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
794                                                 &new->it_interval);
795
796         /*
797          * This acts as a modification timestamp for the timer,
798          * so any automatic reload attempt will punt on seeing
799          * that we have reset the timer manually.
800          */
801         timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
802                 ~REQUEUE_PENDING;
803         timer->it_overrun_last = 0;
804         timer->it_overrun = -1;
805
806         if (new_expires.sched != 0 &&
807             !cpu_time_before(timer->it_clock, val, new_expires)) {
808                 /*
809                  * The designated time already passed, so we notify
810                  * immediately, even if the thread never runs to
811                  * accumulate more time on this clock.
812                  */
813                 cpu_timer_fire(timer);
814         }
815
816         ret = 0;
817  out:
818         if (old) {
819                 sample_to_timespec(timer->it_clock,
820                                    old_incr, &old->it_interval);
821         }
822         return ret;
823 }
824
825 static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
826 {
827         union cpu_time_count now;
828         struct task_struct *p = timer->it.cpu.task;
829         int clear_dead;
830
831         /*
832          * Easy part: convert the reload time.
833          */
834         sample_to_timespec(timer->it_clock,
835                            timer->it.cpu.incr, &itp->it_interval);
836
837         if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all.  */
838                 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
839                 return;
840         }
841
842         if (unlikely(p == NULL)) {
843                 /*
844                  * This task already died and the timer will never fire.
845                  * In this case, expires is actually the dead value.
846                  */
847         dead:
848                 sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
849                                    &itp->it_value);
850                 return;
851         }
852
853         /*
854          * Sample the clock to take the difference with the expiry time.
855          */
856         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
857                 cpu_clock_sample(timer->it_clock, p, &now);
858                 clear_dead = p->exit_state;
859         } else {
860                 read_lock(&tasklist_lock);
861                 if (unlikely(p->sighand == NULL)) {
862                         /*
863                          * The process has been reaped.
864                          * We can't even collect a sample any more.
865                          * Call the timer disarmed, nothing else to do.
866                          */
867                         put_task_struct(p);
868                         timer->it.cpu.task = NULL;
869                         timer->it.cpu.expires.sched = 0;
870                         read_unlock(&tasklist_lock);
871                         goto dead;
872                 } else {
873                         cpu_timer_sample_group(timer->it_clock, p, &now);
874                         clear_dead = (unlikely(p->exit_state) &&
875                                       thread_group_empty(p));
876                 }
877                 read_unlock(&tasklist_lock);
878         }
879
880         if (unlikely(clear_dead)) {
881                 /*
882                  * We've noticed that the thread is dead, but
883                  * not yet reaped.  Take this opportunity to
884                  * drop our task ref.
885                  */
886                 clear_dead_task(timer, now);
887                 goto dead;
888         }
889
890         if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
891                 sample_to_timespec(timer->it_clock,
892                                    cpu_time_sub(timer->it_clock,
893                                                 timer->it.cpu.expires, now),
894                                    &itp->it_value);
895         } else {
896                 /*
897                  * The timer should have expired already, but the firing
898                  * hasn't taken place yet.  Say it's just about to expire.
899                  */
900                 itp->it_value.tv_nsec = 1;
901                 itp->it_value.tv_sec = 0;
902         }
903 }
904
905 /*
906  * Check for any per-thread CPU timers that have fired and move them off
907  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
908  * tsk->it_*_expires values to reflect the remaining thread CPU timers.
909  */
910 static void check_thread_timers(struct task_struct *tsk,
911                                 struct list_head *firing)
912 {
913         int maxfire;
914         struct list_head *timers = tsk->cpu_timers;
915         struct signal_struct *const sig = tsk->signal;
916         unsigned long soft;
917
918         maxfire = 20;
919         tsk->cputime_expires.prof_exp = cputime_zero;
920         while (!list_empty(timers)) {
921                 struct cpu_timer_list *t = list_first_entry(timers,
922                                                       struct cpu_timer_list,
923                                                       entry);
924                 if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
925                         tsk->cputime_expires.prof_exp = t->expires.cpu;
926                         break;
927                 }
928                 t->firing = 1;
929                 list_move_tail(&t->entry, firing);
930         }
931
932         ++timers;
933         maxfire = 20;
934         tsk->cputime_expires.virt_exp = cputime_zero;
935         while (!list_empty(timers)) {
936                 struct cpu_timer_list *t = list_first_entry(timers,
937                                                       struct cpu_timer_list,
938                                                       entry);
939                 if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
940                         tsk->cputime_expires.virt_exp = t->expires.cpu;
941                         break;
942                 }
943                 t->firing = 1;
944                 list_move_tail(&t->entry, firing);
945         }
946
947         ++timers;
948         maxfire = 20;
949         tsk->cputime_expires.sched_exp = 0;
950         while (!list_empty(timers)) {
951                 struct cpu_timer_list *t = list_first_entry(timers,
952                                                       struct cpu_timer_list,
953                                                       entry);
954                 if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
955                         tsk->cputime_expires.sched_exp = t->expires.sched;
956                         break;
957                 }
958                 t->firing = 1;
959                 list_move_tail(&t->entry, firing);
960         }
961
962         /*
963          * Check for the special case thread timers.
964          */
965         soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
966         if (soft != RLIM_INFINITY) {
967                 unsigned long hard =
968                         ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
969
970                 if (hard != RLIM_INFINITY &&
971                     tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
972                         /*
973                          * At the hard limit, we just die.
974                          * No need to calculate anything else now.
975                          */
976                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
977                         return;
978                 }
979                 if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
980                         /*
981                          * At the soft limit, send a SIGXCPU every second.
982                          */
983                         if (soft < hard) {
984                                 soft += USEC_PER_SEC;
985                                 sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
986                         }
987                         printk(KERN_INFO
988                                 "RT Watchdog Timeout: %s[%d]\n",
989                                 tsk->comm, task_pid_nr(tsk));
990                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
991                 }
992         }
993 }
994
995 static void stop_process_timers(struct signal_struct *sig)
996 {
997         struct thread_group_cputimer *cputimer = &sig->cputimer;
998         unsigned long flags;
999
1000         spin_lock_irqsave(&cputimer->lock, flags);
1001         cputimer->running = 0;
1002         spin_unlock_irqrestore(&cputimer->lock, flags);
1003 }
1004
1005 static u32 onecputick;
1006
1007 static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
1008                              cputime_t *expires, cputime_t cur_time, int signo)
1009 {
1010         if (cputime_eq(it->expires, cputime_zero))
1011                 return;
1012
1013         if (cputime_ge(cur_time, it->expires)) {
1014                 if (!cputime_eq(it->incr, cputime_zero)) {
1015                         it->expires = cputime_add(it->expires, it->incr);
1016                         it->error += it->incr_error;
1017                         if (it->error >= onecputick) {
1018                                 it->expires = cputime_sub(it->expires,
1019                                                           cputime_one_jiffy);
1020                                 it->error -= onecputick;
1021                         }
1022                 } else {
1023                         it->expires = cputime_zero;
1024                 }
1025
1026                 trace_itimer_expire(signo == SIGPROF ?
1027                                     ITIMER_PROF : ITIMER_VIRTUAL,
1028                                     tsk->signal->leader_pid, cur_time);
1029                 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
1030         }
1031
1032         if (!cputime_eq(it->expires, cputime_zero) &&
1033             (cputime_eq(*expires, cputime_zero) ||
1034              cputime_lt(it->expires, *expires))) {
1035                 *expires = it->expires;
1036         }
1037 }
1038
1039 /**
1040  * task_cputime_zero - Check a task_cputime struct for all zero fields.
1041  *
1042  * @cputime:    The struct to compare.
1043  *
1044  * Checks @cputime to see if all fields are zero.  Returns true if all fields
1045  * are zero, false if any field is nonzero.
1046  */
1047 static inline int task_cputime_zero(const struct task_cputime *cputime)
1048 {
1049         if (cputime_eq(cputime->utime, cputime_zero) &&
1050             cputime_eq(cputime->stime, cputime_zero) &&
1051             cputime->sum_exec_runtime == 0)
1052                 return 1;
1053         return 0;
1054 }
1055
1056 /*
1057  * Check for any per-thread CPU timers that have fired and move them
1058  * off the tsk->*_timers list onto the firing list.  Per-thread timers
1059  * have already been taken off.
1060  */
1061 static void check_process_timers(struct task_struct *tsk,
1062                                  struct list_head *firing)
1063 {
1064         int maxfire;
1065         struct signal_struct *const sig = tsk->signal;
1066         cputime_t utime, ptime, virt_expires, prof_expires;
1067         unsigned long long sum_sched_runtime, sched_expires;
1068         struct list_head *timers = sig->cpu_timers;
1069         struct task_cputime cputime;
1070         unsigned long soft;
1071
1072         /*
1073          * Collect the current process totals.
1074          */
1075         thread_group_cputimer(tsk, &cputime);
1076         utime = cputime.utime;
1077         ptime = cputime_add(utime, cputime.stime);
1078         sum_sched_runtime = cputime.sum_exec_runtime;
1079         maxfire = 20;
1080         prof_expires = cputime_zero;
1081         while (!list_empty(timers)) {
1082                 struct cpu_timer_list *tl = list_first_entry(timers,
1083                                                       struct cpu_timer_list,
1084                                                       entry);
1085                 if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) {
1086                         prof_expires = tl->expires.cpu;
1087                         break;
1088                 }
1089                 tl->firing = 1;
1090                 list_move_tail(&tl->entry, firing);
1091         }
1092
1093         ++timers;
1094         maxfire = 20;
1095         virt_expires = cputime_zero;
1096         while (!list_empty(timers)) {
1097                 struct cpu_timer_list *tl = list_first_entry(timers,
1098                                                       struct cpu_timer_list,
1099                                                       entry);
1100                 if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) {
1101                         virt_expires = tl->expires.cpu;
1102                         break;
1103                 }
1104                 tl->firing = 1;
1105                 list_move_tail(&tl->entry, firing);
1106         }
1107
1108         ++timers;
1109         maxfire = 20;
1110         sched_expires = 0;
1111         while (!list_empty(timers)) {
1112                 struct cpu_timer_list *tl = list_first_entry(timers,
1113                                                       struct cpu_timer_list,
1114                                                       entry);
1115                 if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1116                         sched_expires = tl->expires.sched;
1117                         break;
1118                 }
1119                 tl->firing = 1;
1120                 list_move_tail(&tl->entry, firing);
1121         }
1122
1123         /*
1124          * Check for the special case process timers.
1125          */
1126         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1127                          SIGPROF);
1128         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1129                          SIGVTALRM);
1130         soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1131         if (soft != RLIM_INFINITY) {
1132                 unsigned long psecs = cputime_to_secs(ptime);
1133                 unsigned long hard =
1134                         ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
1135                 cputime_t x;
1136                 if (psecs >= hard) {
1137                         /*
1138                          * At the hard limit, we just die.
1139                          * No need to calculate anything else now.
1140                          */
1141                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1142                         return;
1143                 }
1144                 if (psecs >= soft) {
1145                         /*
1146                          * At the soft limit, send a SIGXCPU every second.
1147                          */
1148                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1149                         if (soft < hard) {
1150                                 soft++;
1151                                 sig->rlim[RLIMIT_CPU].rlim_cur = soft;
1152                         }
1153                 }
1154                 x = secs_to_cputime(soft);
1155                 if (cputime_eq(prof_expires, cputime_zero) ||
1156                     cputime_lt(x, prof_expires)) {
1157                         prof_expires = x;
1158                 }
1159         }
1160
1161         sig->cputime_expires.prof_exp = prof_expires;
1162         sig->cputime_expires.virt_exp = virt_expires;
1163         sig->cputime_expires.sched_exp = sched_expires;
1164         if (task_cputime_zero(&sig->cputime_expires))
1165                 stop_process_timers(sig);
1166 }
1167
1168 /*
1169  * This is called from the signal code (via do_schedule_next_timer)
1170  * when the last timer signal was delivered and we have to reload the timer.
1171  */
1172 void posix_cpu_timer_schedule(struct k_itimer *timer)
1173 {
1174         struct task_struct *p = timer->it.cpu.task;
1175         union cpu_time_count now;
1176
1177         if (unlikely(p == NULL))
1178                 /*
1179                  * The task was cleaned up already, no future firings.
1180                  */
1181                 goto out;
1182
1183         /*
1184          * Fetch the current sample and update the timer's expiry time.
1185          */
1186         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1187                 cpu_clock_sample(timer->it_clock, p, &now);
1188                 bump_cpu_timer(timer, now);
1189                 if (unlikely(p->exit_state)) {
1190                         clear_dead_task(timer, now);
1191                         goto out;
1192                 }
1193                 read_lock(&tasklist_lock); /* arm_timer needs it.  */
1194                 spin_lock(&p->sighand->siglock);
1195         } else {
1196                 read_lock(&tasklist_lock);
1197                 if (unlikely(p->sighand == NULL)) {
1198                         /*
1199                          * The process has been reaped.
1200                          * We can't even collect a sample any more.
1201                          */
1202                         put_task_struct(p);
1203                         timer->it.cpu.task = p = NULL;
1204                         timer->it.cpu.expires.sched = 0;
1205                         goto out_unlock;
1206                 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1207                         /*
1208                          * We've noticed that the thread is dead, but
1209                          * not yet reaped.  Take this opportunity to
1210                          * drop our task ref.
1211                          */
1212                         clear_dead_task(timer, now);
1213                         goto out_unlock;
1214                 }
1215                 spin_lock(&p->sighand->siglock);
1216                 cpu_timer_sample_group(timer->it_clock, p, &now);
1217                 bump_cpu_timer(timer, now);
1218                 /* Leave the tasklist_lock locked for the call below.  */
1219         }
1220
1221         /*
1222          * Now re-arm for the new expiry time.
1223          */
1224         BUG_ON(!irqs_disabled());
1225         arm_timer(timer);
1226         spin_unlock(&p->sighand->siglock);
1227
1228 out_unlock:
1229         read_unlock(&tasklist_lock);
1230
1231 out:
1232         timer->it_overrun_last = timer->it_overrun;
1233         timer->it_overrun = -1;
1234         ++timer->it_requeue_pending;
1235 }
1236
1237 /**
1238  * task_cputime_expired - Compare two task_cputime entities.
1239  *
1240  * @sample:     The task_cputime structure to be checked for expiration.
1241  * @expires:    Expiration times, against which @sample will be checked.
1242  *
1243  * Checks @sample against @expires to see if any field of @sample has expired.
1244  * Returns true if any field of the former is greater than the corresponding
1245  * field of the latter if the latter field is set.  Otherwise returns false.
1246  */
1247 static inline int task_cputime_expired(const struct task_cputime *sample,
1248                                         const struct task_cputime *expires)
1249 {
1250         if (!cputime_eq(expires->utime, cputime_zero) &&
1251             cputime_ge(sample->utime, expires->utime))
1252                 return 1;
1253         if (!cputime_eq(expires->stime, cputime_zero) &&
1254             cputime_ge(cputime_add(sample->utime, sample->stime),
1255                        expires->stime))
1256                 return 1;
1257         if (expires->sum_exec_runtime != 0 &&
1258             sample->sum_exec_runtime >= expires->sum_exec_runtime)
1259                 return 1;
1260         return 0;
1261 }
1262
1263 /**
1264  * fastpath_timer_check - POSIX CPU timers fast path.
1265  *
1266  * @tsk:        The task (thread) being checked.
1267  *
1268  * Check the task and thread group timers.  If both are zero (there are no
1269  * timers set) return false.  Otherwise snapshot the task and thread group
1270  * timers and compare them with the corresponding expiration times.  Return
1271  * true if a timer has expired, else return false.
1272  */
1273 static inline int fastpath_timer_check(struct task_struct *tsk)
1274 {
1275         struct signal_struct *sig;
1276
1277         if (!task_cputime_zero(&tsk->cputime_expires)) {
1278                 struct task_cputime task_sample = {
1279                         .utime = tsk->utime,
1280                         .stime = tsk->stime,
1281                         .sum_exec_runtime = tsk->se.sum_exec_runtime
1282                 };
1283
1284                 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1285                         return 1;
1286         }
1287
1288         sig = tsk->signal;
1289         if (sig->cputimer.running) {
1290                 struct task_cputime group_sample;
1291
1292                 spin_lock(&sig->cputimer.lock);
1293                 group_sample = sig->cputimer.cputime;
1294                 spin_unlock(&sig->cputimer.lock);
1295
1296                 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1297                         return 1;
1298         }
1299
1300         return 0;
1301 }
1302
1303 /*
1304  * This is called from the timer interrupt handler.  The irq handler has
1305  * already updated our counts.  We need to check if any timers fire now.
1306  * Interrupts are disabled.
1307  */
1308 void run_posix_cpu_timers(struct task_struct *tsk)
1309 {
1310         LIST_HEAD(firing);
1311         struct k_itimer *timer, *next;
1312         unsigned long flags;
1313
1314         BUG_ON(!irqs_disabled());
1315
1316         /*
1317          * The fast path checks that there are no expired thread or thread
1318          * group timers.  If that's so, just return.
1319          */
1320         if (!fastpath_timer_check(tsk))
1321                 return;
1322
1323         if (!lock_task_sighand(tsk, &flags))
1324                 return;
1325         /*
1326          * Here we take off tsk->signal->cpu_timers[N] and
1327          * tsk->cpu_timers[N] all the timers that are firing, and
1328          * put them on the firing list.
1329          */
1330         check_thread_timers(tsk, &firing);
1331         /*
1332          * If there are any active process wide timers (POSIX 1.b, itimers,
1333          * RLIMIT_CPU) cputimer must be running.
1334          */
1335         if (tsk->signal->cputimer.running)
1336                 check_process_timers(tsk, &firing);
1337
1338         /*
1339          * We must release these locks before taking any timer's lock.
1340          * There is a potential race with timer deletion here, as the
1341          * siglock now protects our private firing list.  We have set
1342          * the firing flag in each timer, so that a deletion attempt
1343          * that gets the timer lock before we do will give it up and
1344          * spin until we've taken care of that timer below.
1345          */
1346         unlock_task_sighand(tsk, &flags);
1347
1348         /*
1349          * Now that all the timers on our list have the firing flag,
1350          * no one will touch their list entries but us.  We'll take
1351          * each timer's lock before clearing its firing flag, so no
1352          * timer call will interfere.
1353          */
1354         list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1355                 int cpu_firing;
1356
1357                 spin_lock(&timer->it_lock);
1358                 list_del_init(&timer->it.cpu.entry);
1359                 cpu_firing = timer->it.cpu.firing;
1360                 timer->it.cpu.firing = 0;
1361                 /*
1362                  * The firing flag is -1 if we collided with a reset
1363                  * of the timer, which already reported this
1364                  * almost-firing as an overrun.  So don't generate an event.
1365                  */
1366                 if (likely(cpu_firing >= 0))
1367                         cpu_timer_fire(timer);
1368                 spin_unlock(&timer->it_lock);
1369         }
1370 }
1371
1372 /*
1373  * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1374  * The tsk->sighand->siglock must be held by the caller.
1375  */
1376 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1377                            cputime_t *newval, cputime_t *oldval)
1378 {
1379         union cpu_time_count now;
1380
1381         BUG_ON(clock_idx == CPUCLOCK_SCHED);
1382         cpu_timer_sample_group(clock_idx, tsk, &now);
1383
1384         if (oldval) {
1385                 /*
1386                  * We are setting itimer. The *oldval is absolute and we update
1387                  * it to be relative, *newval argument is relative and we update
1388                  * it to be absolute.
1389                  */
1390                 if (!cputime_eq(*oldval, cputime_zero)) {
1391                         if (cputime_le(*oldval, now.cpu)) {
1392                                 /* Just about to fire. */
1393                                 *oldval = cputime_one_jiffy;
1394                         } else {
1395                                 *oldval = cputime_sub(*oldval, now.cpu);
1396                         }
1397                 }
1398
1399                 if (cputime_eq(*newval, cputime_zero))
1400                         return;
1401                 *newval = cputime_add(*newval, now.cpu);
1402         }
1403
1404         /*
1405          * Update expiration cache if we are the earliest timer, or eventually
1406          * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1407          */
1408         switch (clock_idx) {
1409         case CPUCLOCK_PROF:
1410                 if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1411                         tsk->signal->cputime_expires.prof_exp = *newval;
1412                 break;
1413         case CPUCLOCK_VIRT:
1414                 if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1415                         tsk->signal->cputime_expires.virt_exp = *newval;
1416                 break;
1417         }
1418 }
1419
1420 static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1421                             struct timespec *rqtp, struct itimerspec *it)
1422 {
1423         struct k_itimer timer;
1424         int error;
1425
1426         /*
1427          * Set up a temporary timer and then wait for it to go off.
1428          */
1429         memset(&timer, 0, sizeof timer);
1430         spin_lock_init(&timer.it_lock);
1431         timer.it_clock = which_clock;
1432         timer.it_overrun = -1;
1433         error = posix_cpu_timer_create(&timer);
1434         timer.it_process = current;
1435         if (!error) {
1436                 static struct itimerspec zero_it;
1437
1438                 memset(it, 0, sizeof *it);
1439                 it->it_value = *rqtp;
1440
1441                 spin_lock_irq(&timer.it_lock);
1442                 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1443                 if (error) {
1444                         spin_unlock_irq(&timer.it_lock);
1445                         return error;
1446                 }
1447
1448                 while (!signal_pending(current)) {
1449                         if (timer.it.cpu.expires.sched == 0) {
1450                                 /*
1451                                  * Our timer fired and was reset.
1452                                  */
1453                                 spin_unlock_irq(&timer.it_lock);
1454                                 return 0;
1455                         }
1456
1457                         /*
1458                          * Block until cpu_timer_fire (or a signal) wakes us.
1459                          */
1460                         __set_current_state(TASK_INTERRUPTIBLE);
1461                         spin_unlock_irq(&timer.it_lock);
1462                         schedule();
1463                         spin_lock_irq(&timer.it_lock);
1464                 }
1465
1466                 /*
1467                  * We were interrupted by a signal.
1468                  */
1469                 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1470                 posix_cpu_timer_set(&timer, 0, &zero_it, it);
1471                 spin_unlock_irq(&timer.it_lock);
1472
1473                 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1474                         /*
1475                          * It actually did fire already.
1476                          */
1477                         return 0;
1478                 }
1479
1480                 error = -ERESTART_RESTARTBLOCK;
1481         }
1482
1483         return error;
1484 }
1485
1486 static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1487
1488 static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1489                             struct timespec *rqtp, struct timespec __user *rmtp)
1490 {
1491         struct restart_block *restart_block =
1492                 &current_thread_info()->restart_block;
1493         struct itimerspec it;
1494         int error;
1495
1496         /*
1497          * Diagnose required errors first.
1498          */
1499         if (CPUCLOCK_PERTHREAD(which_clock) &&
1500             (CPUCLOCK_PID(which_clock) == 0 ||
1501              CPUCLOCK_PID(which_clock) == current->pid))
1502                 return -EINVAL;
1503
1504         error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1505
1506         if (error == -ERESTART_RESTARTBLOCK) {
1507
1508                 if (flags & TIMER_ABSTIME)
1509                         return -ERESTARTNOHAND;
1510                 /*
1511                  * Report back to the user the time still remaining.
1512                  */
1513                 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1514                         return -EFAULT;
1515
1516                 restart_block->fn = posix_cpu_nsleep_restart;
1517                 restart_block->nanosleep.clockid = which_clock;
1518                 restart_block->nanosleep.rmtp = rmtp;
1519                 restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1520         }
1521         return error;
1522 }
1523
1524 static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1525 {
1526         clockid_t which_clock = restart_block->nanosleep.clockid;
1527         struct timespec t;
1528         struct itimerspec it;
1529         int error;
1530
1531         t = ns_to_timespec(restart_block->nanosleep.expires);
1532
1533         error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1534
1535         if (error == -ERESTART_RESTARTBLOCK) {
1536                 struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1537                 /*
1538                  * Report back to the user the time still remaining.
1539                  */
1540                 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1541                         return -EFAULT;
1542
1543                 restart_block->nanosleep.expires = timespec_to_ns(&t);
1544         }
1545         return error;
1546
1547 }
1548
1549 #define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1550 #define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1551
1552 static int process_cpu_clock_getres(const clockid_t which_clock,
1553                                     struct timespec *tp)
1554 {
1555         return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1556 }
1557 static int process_cpu_clock_get(const clockid_t which_clock,
1558                                  struct timespec *tp)
1559 {
1560         return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1561 }
1562 static int process_cpu_timer_create(struct k_itimer *timer)
1563 {
1564         timer->it_clock = PROCESS_CLOCK;
1565         return posix_cpu_timer_create(timer);
1566 }
1567 static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1568                               struct timespec *rqtp,
1569                               struct timespec __user *rmtp)
1570 {
1571         return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1572 }
1573 static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1574 {
1575         return -EINVAL;
1576 }
1577 static int thread_cpu_clock_getres(const clockid_t which_clock,
1578                                    struct timespec *tp)
1579 {
1580         return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1581 }
1582 static int thread_cpu_clock_get(const clockid_t which_clock,
1583                                 struct timespec *tp)
1584 {
1585         return posix_cpu_clock_get(THREAD_CLOCK, tp);
1586 }
1587 static int thread_cpu_timer_create(struct k_itimer *timer)
1588 {
1589         timer->it_clock = THREAD_CLOCK;
1590         return posix_cpu_timer_create(timer);
1591 }
1592
1593 struct k_clock clock_posix_cpu = {
1594         .clock_getres   = posix_cpu_clock_getres,
1595         .clock_set      = posix_cpu_clock_set,
1596         .clock_get      = posix_cpu_clock_get,
1597         .timer_create   = posix_cpu_timer_create,
1598         .nsleep         = posix_cpu_nsleep,
1599         .nsleep_restart = posix_cpu_nsleep_restart,
1600         .timer_set      = posix_cpu_timer_set,
1601         .timer_del      = posix_cpu_timer_del,
1602         .timer_get      = posix_cpu_timer_get,
1603 };
1604
1605 static __init int init_posix_cpu_timers(void)
1606 {
1607         struct k_clock process = {
1608                 .clock_getres   = process_cpu_clock_getres,
1609                 .clock_get      = process_cpu_clock_get,
1610                 .timer_create   = process_cpu_timer_create,
1611                 .nsleep         = process_cpu_nsleep,
1612                 .nsleep_restart = process_cpu_nsleep_restart,
1613         };
1614         struct k_clock thread = {
1615                 .clock_getres   = thread_cpu_clock_getres,
1616                 .clock_get      = thread_cpu_clock_get,
1617                 .timer_create   = thread_cpu_timer_create,
1618         };
1619         struct timespec ts;
1620
1621         posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1622         posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1623
1624         cputime_to_timespec(cputime_one_jiffy, &ts);
1625         onecputick = ts.tv_nsec;
1626         WARN_ON(ts.tv_sec != 0);
1627
1628         return 0;
1629 }
1630 __initcall(init_posix_cpu_timers);