]> nv-tegra.nvidia Code Review - linux-2.6.git/blob - kernel/posix-cpu-timers.c
[PATCH] posix-timers: exit path cleanup
[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 <asm/uaccess.h>
8 #include <linux/errno.h>
9
10 static int check_clock(clockid_t which_clock)
11 {
12         int error = 0;
13         struct task_struct *p;
14         const pid_t pid = CPUCLOCK_PID(which_clock);
15
16         if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
17                 return -EINVAL;
18
19         if (pid == 0)
20                 return 0;
21
22         read_lock(&tasklist_lock);
23         p = find_task_by_pid(pid);
24         if (!p || (CPUCLOCK_PERTHREAD(which_clock) ?
25                    p->tgid != current->tgid : p->tgid != pid)) {
26                 error = -EINVAL;
27         }
28         read_unlock(&tasklist_lock);
29
30         return error;
31 }
32
33 static inline union cpu_time_count
34 timespec_to_sample(clockid_t which_clock, const struct timespec *tp)
35 {
36         union cpu_time_count ret;
37         ret.sched = 0;          /* high half always zero when .cpu used */
38         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
39                 ret.sched = tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
40         } else {
41                 ret.cpu = timespec_to_cputime(tp);
42         }
43         return ret;
44 }
45
46 static void sample_to_timespec(clockid_t which_clock,
47                                union cpu_time_count cpu,
48                                struct timespec *tp)
49 {
50         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
51                 tp->tv_sec = div_long_long_rem(cpu.sched,
52                                                NSEC_PER_SEC, &tp->tv_nsec);
53         } else {
54                 cputime_to_timespec(cpu.cpu, tp);
55         }
56 }
57
58 static inline int cpu_time_before(clockid_t which_clock,
59                                   union cpu_time_count now,
60                                   union cpu_time_count then)
61 {
62         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
63                 return now.sched < then.sched;
64         }  else {
65                 return cputime_lt(now.cpu, then.cpu);
66         }
67 }
68 static inline void cpu_time_add(clockid_t which_clock,
69                                 union cpu_time_count *acc,
70                                 union cpu_time_count val)
71 {
72         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
73                 acc->sched += val.sched;
74         }  else {
75                 acc->cpu = cputime_add(acc->cpu, val.cpu);
76         }
77 }
78 static inline union cpu_time_count cpu_time_sub(clockid_t which_clock,
79                                                 union cpu_time_count a,
80                                                 union cpu_time_count b)
81 {
82         if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
83                 a.sched -= b.sched;
84         }  else {
85                 a.cpu = cputime_sub(a.cpu, b.cpu);
86         }
87         return a;
88 }
89
90 /*
91  * Update expiry time from increment, and increase overrun count,
92  * given the current clock sample.
93  */
94 static inline void bump_cpu_timer(struct k_itimer *timer,
95                                   union cpu_time_count now)
96 {
97         int i;
98
99         if (timer->it.cpu.incr.sched == 0)
100                 return;
101
102         if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
103                 unsigned long long delta, incr;
104
105                 if (now.sched < timer->it.cpu.expires.sched)
106                         return;
107                 incr = timer->it.cpu.incr.sched;
108                 delta = now.sched + incr - timer->it.cpu.expires.sched;
109                 /* Don't use (incr*2 < delta), incr*2 might overflow. */
110                 for (i = 0; incr < delta - incr; i++)
111                         incr = incr << 1;
112                 for (; i >= 0; incr >>= 1, i--) {
113                         if (delta <= incr)
114                                 continue;
115                         timer->it.cpu.expires.sched += incr;
116                         timer->it_overrun += 1 << i;
117                         delta -= incr;
118                 }
119         } else {
120                 cputime_t delta, incr;
121
122                 if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu))
123                         return;
124                 incr = timer->it.cpu.incr.cpu;
125                 delta = cputime_sub(cputime_add(now.cpu, incr),
126                                     timer->it.cpu.expires.cpu);
127                 /* Don't use (incr*2 < delta), incr*2 might overflow. */
128                 for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
129                              incr = cputime_add(incr, incr);
130                 for (; i >= 0; incr = cputime_halve(incr), i--) {
131                         if (cputime_le(delta, incr))
132                                 continue;
133                         timer->it.cpu.expires.cpu =
134                                 cputime_add(timer->it.cpu.expires.cpu, incr);
135                         timer->it_overrun += 1 << i;
136                         delta = cputime_sub(delta, incr);
137                 }
138         }
139 }
140
141 static inline cputime_t prof_ticks(struct task_struct *p)
142 {
143         return cputime_add(p->utime, p->stime);
144 }
145 static inline cputime_t virt_ticks(struct task_struct *p)
146 {
147         return p->utime;
148 }
149 static inline unsigned long long sched_ns(struct task_struct *p)
150 {
151         return (p == current) ? current_sched_time(p) : p->sched_time;
152 }
153
154 int posix_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
155 {
156         int error = check_clock(which_clock);
157         if (!error) {
158                 tp->tv_sec = 0;
159                 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
160                 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
161                         /*
162                          * If sched_clock is using a cycle counter, we
163                          * don't have any idea of its true resolution
164                          * exported, but it is much more than 1s/HZ.
165                          */
166                         tp->tv_nsec = 1;
167                 }
168         }
169         return error;
170 }
171
172 int posix_cpu_clock_set(clockid_t which_clock, const struct timespec *tp)
173 {
174         /*
175          * You can never reset a CPU clock, but we check for other errors
176          * in the call before failing with EPERM.
177          */
178         int error = check_clock(which_clock);
179         if (error == 0) {
180                 error = -EPERM;
181         }
182         return error;
183 }
184
185
186 /*
187  * Sample a per-thread clock for the given task.
188  */
189 static int cpu_clock_sample(clockid_t which_clock, struct task_struct *p,
190                             union cpu_time_count *cpu)
191 {
192         switch (CPUCLOCK_WHICH(which_clock)) {
193         default:
194                 return -EINVAL;
195         case CPUCLOCK_PROF:
196                 cpu->cpu = prof_ticks(p);
197                 break;
198         case CPUCLOCK_VIRT:
199                 cpu->cpu = virt_ticks(p);
200                 break;
201         case CPUCLOCK_SCHED:
202                 cpu->sched = sched_ns(p);
203                 break;
204         }
205         return 0;
206 }
207
208 /*
209  * Sample a process (thread group) clock for the given group_leader task.
210  * Must be called with tasklist_lock held for reading.
211  * Must be called with tasklist_lock held for reading, and p->sighand->siglock.
212  */
213 static int cpu_clock_sample_group_locked(unsigned int clock_idx,
214                                          struct task_struct *p,
215                                          union cpu_time_count *cpu)
216 {
217         struct task_struct *t = p;
218         switch (clock_idx) {
219         default:
220                 return -EINVAL;
221         case CPUCLOCK_PROF:
222                 cpu->cpu = cputime_add(p->signal->utime, p->signal->stime);
223                 do {
224                         cpu->cpu = cputime_add(cpu->cpu, prof_ticks(t));
225                         t = next_thread(t);
226                 } while (t != p);
227                 break;
228         case CPUCLOCK_VIRT:
229                 cpu->cpu = p->signal->utime;
230                 do {
231                         cpu->cpu = cputime_add(cpu->cpu, virt_ticks(t));
232                         t = next_thread(t);
233                 } while (t != p);
234                 break;
235         case CPUCLOCK_SCHED:
236                 cpu->sched = p->signal->sched_time;
237                 /* Add in each other live thread.  */
238                 while ((t = next_thread(t)) != p) {
239                         cpu->sched += t->sched_time;
240                 }
241                 if (p->tgid == current->tgid) {
242                         /*
243                          * We're sampling ourselves, so include the
244                          * cycles not yet banked.  We still omit
245                          * other threads running on other CPUs,
246                          * so the total can always be behind as
247                          * much as max(nthreads-1,ncpus) * (NSEC_PER_SEC/HZ).
248                          */
249                         cpu->sched += current_sched_time(current);
250                 } else {
251                         cpu->sched += p->sched_time;
252                 }
253                 break;
254         }
255         return 0;
256 }
257
258 /*
259  * Sample a process (thread group) clock for the given group_leader task.
260  * Must be called with tasklist_lock held for reading.
261  */
262 static int cpu_clock_sample_group(clockid_t which_clock,
263                                   struct task_struct *p,
264                                   union cpu_time_count *cpu)
265 {
266         int ret;
267         unsigned long flags;
268         spin_lock_irqsave(&p->sighand->siglock, flags);
269         ret = cpu_clock_sample_group_locked(CPUCLOCK_WHICH(which_clock), p,
270                                             cpu);
271         spin_unlock_irqrestore(&p->sighand->siglock, flags);
272         return ret;
273 }
274
275
276 int posix_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
277 {
278         const pid_t pid = CPUCLOCK_PID(which_clock);
279         int error = -EINVAL;
280         union cpu_time_count rtn;
281
282         if (pid == 0) {
283                 /*
284                  * Special case constant value for our own clocks.
285                  * We don't have to do any lookup to find ourselves.
286                  */
287                 if (CPUCLOCK_PERTHREAD(which_clock)) {
288                         /*
289                          * Sampling just ourselves we can do with no locking.
290                          */
291                         error = cpu_clock_sample(which_clock,
292                                                  current, &rtn);
293                 } else {
294                         read_lock(&tasklist_lock);
295                         error = cpu_clock_sample_group(which_clock,
296                                                        current, &rtn);
297                         read_unlock(&tasklist_lock);
298                 }
299         } else {
300                 /*
301                  * Find the given PID, and validate that the caller
302                  * should be able to see it.
303                  */
304                 struct task_struct *p;
305                 read_lock(&tasklist_lock);
306                 p = find_task_by_pid(pid);
307                 if (p) {
308                         if (CPUCLOCK_PERTHREAD(which_clock)) {
309                                 if (p->tgid == current->tgid) {
310                                         error = cpu_clock_sample(which_clock,
311                                                                  p, &rtn);
312                                 }
313                         } else if (p->tgid == pid && p->signal) {
314                                 error = cpu_clock_sample_group(which_clock,
315                                                                p, &rtn);
316                         }
317                 }
318                 read_unlock(&tasklist_lock);
319         }
320
321         if (error)
322                 return error;
323         sample_to_timespec(which_clock, rtn, tp);
324         return 0;
325 }
326
327
328 /*
329  * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
330  * This is called from sys_timer_create with the new timer already locked.
331  */
332 int posix_cpu_timer_create(struct k_itimer *new_timer)
333 {
334         int ret = 0;
335         const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
336         struct task_struct *p;
337
338         if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
339                 return -EINVAL;
340
341         INIT_LIST_HEAD(&new_timer->it.cpu.entry);
342         new_timer->it.cpu.incr.sched = 0;
343         new_timer->it.cpu.expires.sched = 0;
344
345         read_lock(&tasklist_lock);
346         if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
347                 if (pid == 0) {
348                         p = current;
349                 } else {
350                         p = find_task_by_pid(pid);
351                         if (p && p->tgid != current->tgid)
352                                 p = NULL;
353                 }
354         } else {
355                 if (pid == 0) {
356                         p = current->group_leader;
357                 } else {
358                         p = find_task_by_pid(pid);
359                         if (p && p->tgid != pid)
360                                 p = NULL;
361                 }
362         }
363         new_timer->it.cpu.task = p;
364         if (p) {
365                 get_task_struct(p);
366         } else {
367                 ret = -EINVAL;
368         }
369         read_unlock(&tasklist_lock);
370
371         return ret;
372 }
373
374 /*
375  * Clean up a CPU-clock timer that is about to be destroyed.
376  * This is called from timer deletion with the timer already locked.
377  * If we return TIMER_RETRY, it's necessary to release the timer's lock
378  * and try again.  (This happens when the timer is in the middle of firing.)
379  */
380 int posix_cpu_timer_del(struct k_itimer *timer)
381 {
382         struct task_struct *p = timer->it.cpu.task;
383         int ret = 0;
384
385         if (likely(p != NULL)) {
386                 read_lock(&tasklist_lock);
387                 if (unlikely(p->signal == NULL)) {
388                         /*
389                          * We raced with the reaping of the task.
390                          * The deletion should have cleared us off the list.
391                          */
392                         BUG_ON(!list_empty(&timer->it.cpu.entry));
393                 } else {
394                         spin_lock(&p->sighand->siglock);
395                         if (timer->it.cpu.firing)
396                                 ret = TIMER_RETRY;
397                         else
398                                 list_del(&timer->it.cpu.entry);
399                         spin_unlock(&p->sighand->siglock);
400                 }
401                 read_unlock(&tasklist_lock);
402
403                 if (!ret)
404                         put_task_struct(p);
405         }
406
407         return ret;
408 }
409
410 /*
411  * Clean out CPU timers still ticking when a thread exited.  The task
412  * pointer is cleared, and the expiry time is replaced with the residual
413  * time for later timer_gettime calls to return.
414  * This must be called with the siglock held.
415  */
416 static void cleanup_timers(struct list_head *head,
417                            cputime_t utime, cputime_t stime,
418                            unsigned long long sched_time)
419 {
420         struct cpu_timer_list *timer, *next;
421         cputime_t ptime = cputime_add(utime, stime);
422
423         list_for_each_entry_safe(timer, next, head, entry) {
424                 list_del_init(&timer->entry);
425                 if (cputime_lt(timer->expires.cpu, ptime)) {
426                         timer->expires.cpu = cputime_zero;
427                 } else {
428                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
429                                                          ptime);
430                 }
431         }
432
433         ++head;
434         list_for_each_entry_safe(timer, next, head, entry) {
435                 list_del_init(&timer->entry);
436                 if (cputime_lt(timer->expires.cpu, utime)) {
437                         timer->expires.cpu = cputime_zero;
438                 } else {
439                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
440                                                          utime);
441                 }
442         }
443
444         ++head;
445         list_for_each_entry_safe(timer, next, head, entry) {
446                 list_del_init(&timer->entry);
447                 if (timer->expires.sched < sched_time) {
448                         timer->expires.sched = 0;
449                 } else {
450                         timer->expires.sched -= sched_time;
451                 }
452         }
453 }
454
455 /*
456  * These are both called with the siglock held, when the current thread
457  * is being reaped.  When the final (leader) thread in the group is reaped,
458  * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
459  */
460 void posix_cpu_timers_exit(struct task_struct *tsk)
461 {
462         cleanup_timers(tsk->cpu_timers,
463                        tsk->utime, tsk->stime, tsk->sched_time);
464
465 }
466 void posix_cpu_timers_exit_group(struct task_struct *tsk)
467 {
468         cleanup_timers(tsk->signal->cpu_timers,
469                        cputime_add(tsk->utime, tsk->signal->utime),
470                        cputime_add(tsk->stime, tsk->signal->stime),
471                        tsk->sched_time + tsk->signal->sched_time);
472 }
473
474
475 /*
476  * Set the expiry times of all the threads in the process so one of them
477  * will go off before the process cumulative expiry total is reached.
478  */
479 static void process_timer_rebalance(struct task_struct *p,
480                                     unsigned int clock_idx,
481                                     union cpu_time_count expires,
482                                     union cpu_time_count val)
483 {
484         cputime_t ticks, left;
485         unsigned long long ns, nsleft;
486         struct task_struct *t = p;
487         unsigned int nthreads = atomic_read(&p->signal->live);
488
489         if (!nthreads)
490                 return;
491
492         switch (clock_idx) {
493         default:
494                 BUG();
495                 break;
496         case CPUCLOCK_PROF:
497                 left = cputime_div(cputime_sub(expires.cpu, val.cpu),
498                                    nthreads);
499                 do {
500                         if (!unlikely(t->exit_state)) {
501                                 ticks = cputime_add(prof_ticks(t), left);
502                                 if (cputime_eq(t->it_prof_expires,
503                                                cputime_zero) ||
504                                     cputime_gt(t->it_prof_expires, ticks)) {
505                                         t->it_prof_expires = ticks;
506                                 }
507                         }
508                         t = next_thread(t);
509                 } while (t != p);
510                 break;
511         case CPUCLOCK_VIRT:
512                 left = cputime_div(cputime_sub(expires.cpu, val.cpu),
513                                    nthreads);
514                 do {
515                         if (!unlikely(t->exit_state)) {
516                                 ticks = cputime_add(virt_ticks(t), left);
517                                 if (cputime_eq(t->it_virt_expires,
518                                                cputime_zero) ||
519                                     cputime_gt(t->it_virt_expires, ticks)) {
520                                         t->it_virt_expires = ticks;
521                                 }
522                         }
523                         t = next_thread(t);
524                 } while (t != p);
525                 break;
526         case CPUCLOCK_SCHED:
527                 nsleft = expires.sched - val.sched;
528                 do_div(nsleft, nthreads);
529                 do {
530                         if (!unlikely(t->exit_state)) {
531                                 ns = t->sched_time + nsleft;
532                                 if (t->it_sched_expires == 0 ||
533                                     t->it_sched_expires > ns) {
534                                         t->it_sched_expires = ns;
535                                 }
536                         }
537                         t = next_thread(t);
538                 } while (t != p);
539                 break;
540         }
541 }
542
543 static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
544 {
545         /*
546          * That's all for this thread or process.
547          * We leave our residual in expires to be reported.
548          */
549         put_task_struct(timer->it.cpu.task);
550         timer->it.cpu.task = NULL;
551         timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
552                                              timer->it.cpu.expires,
553                                              now);
554 }
555
556 /*
557  * Insert the timer on the appropriate list before any timers that
558  * expire later.  This must be called with the tasklist_lock held
559  * for reading, and interrupts disabled.
560  */
561 static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
562 {
563         struct task_struct *p = timer->it.cpu.task;
564         struct list_head *head, *listpos;
565         struct cpu_timer_list *const nt = &timer->it.cpu;
566         struct cpu_timer_list *next;
567         unsigned long i;
568
569         head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?
570                 p->cpu_timers : p->signal->cpu_timers);
571         head += CPUCLOCK_WHICH(timer->it_clock);
572
573         BUG_ON(!irqs_disabled());
574         spin_lock(&p->sighand->siglock);
575
576         listpos = head;
577         if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
578                 list_for_each_entry(next, head, entry) {
579                         if (next->expires.sched > nt->expires.sched) {
580                                 listpos = &next->entry;
581                                 break;
582                         }
583                 }
584         } else {
585                 list_for_each_entry(next, head, entry) {
586                         if (cputime_gt(next->expires.cpu, nt->expires.cpu)) {
587                                 listpos = &next->entry;
588                                 break;
589                         }
590                 }
591         }
592         list_add(&nt->entry, listpos);
593
594         if (listpos == head) {
595                 /*
596                  * We are the new earliest-expiring timer.
597                  * If we are a thread timer, there can always
598                  * be a process timer telling us to stop earlier.
599                  */
600
601                 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
602                         switch (CPUCLOCK_WHICH(timer->it_clock)) {
603                         default:
604                                 BUG();
605                         case CPUCLOCK_PROF:
606                                 if (cputime_eq(p->it_prof_expires,
607                                                cputime_zero) ||
608                                     cputime_gt(p->it_prof_expires,
609                                                nt->expires.cpu))
610                                         p->it_prof_expires = nt->expires.cpu;
611                                 break;
612                         case CPUCLOCK_VIRT:
613                                 if (cputime_eq(p->it_virt_expires,
614                                                cputime_zero) ||
615                                     cputime_gt(p->it_virt_expires,
616                                                nt->expires.cpu))
617                                         p->it_virt_expires = nt->expires.cpu;
618                                 break;
619                         case CPUCLOCK_SCHED:
620                                 if (p->it_sched_expires == 0 ||
621                                     p->it_sched_expires > nt->expires.sched)
622                                         p->it_sched_expires = nt->expires.sched;
623                                 break;
624                         }
625                 } else {
626                         /*
627                          * For a process timer, we must balance
628                          * all the live threads' expirations.
629                          */
630                         switch (CPUCLOCK_WHICH(timer->it_clock)) {
631                         default:
632                                 BUG();
633                         case CPUCLOCK_VIRT:
634                                 if (!cputime_eq(p->signal->it_virt_expires,
635                                                 cputime_zero) &&
636                                     cputime_lt(p->signal->it_virt_expires,
637                                                timer->it.cpu.expires.cpu))
638                                         break;
639                                 goto rebalance;
640                         case CPUCLOCK_PROF:
641                                 if (!cputime_eq(p->signal->it_prof_expires,
642                                                 cputime_zero) &&
643                                     cputime_lt(p->signal->it_prof_expires,
644                                                timer->it.cpu.expires.cpu))
645                                         break;
646                                 i = p->signal->rlim[RLIMIT_CPU].rlim_cur;
647                                 if (i != RLIM_INFINITY &&
648                                     i <= cputime_to_secs(timer->it.cpu.expires.cpu))
649                                         break;
650                                 goto rebalance;
651                         case CPUCLOCK_SCHED:
652                         rebalance:
653                                 process_timer_rebalance(
654                                         timer->it.cpu.task,
655                                         CPUCLOCK_WHICH(timer->it_clock),
656                                         timer->it.cpu.expires, now);
657                                 break;
658                         }
659                 }
660         }
661
662         spin_unlock(&p->sighand->siglock);
663 }
664
665 /*
666  * The timer is locked, fire it and arrange for its reload.
667  */
668 static void cpu_timer_fire(struct k_itimer *timer)
669 {
670         if (unlikely(timer->sigq == NULL)) {
671                 /*
672                  * This a special case for clock_nanosleep,
673                  * not a normal timer from sys_timer_create.
674                  */
675                 wake_up_process(timer->it_process);
676                 timer->it.cpu.expires.sched = 0;
677         } else if (timer->it.cpu.incr.sched == 0) {
678                 /*
679                  * One-shot timer.  Clear it as soon as it's fired.
680                  */
681                 posix_timer_event(timer, 0);
682                 timer->it.cpu.expires.sched = 0;
683         } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
684                 /*
685                  * The signal did not get queued because the signal
686                  * was ignored, so we won't get any callback to
687                  * reload the timer.  But we need to keep it
688                  * ticking in case the signal is deliverable next time.
689                  */
690                 posix_cpu_timer_schedule(timer);
691         }
692 }
693
694 /*
695  * Guts of sys_timer_settime for CPU timers.
696  * This is called with the timer locked and interrupts disabled.
697  * If we return TIMER_RETRY, it's necessary to release the timer's lock
698  * and try again.  (This happens when the timer is in the middle of firing.)
699  */
700 int posix_cpu_timer_set(struct k_itimer *timer, int flags,
701                         struct itimerspec *new, struct itimerspec *old)
702 {
703         struct task_struct *p = timer->it.cpu.task;
704         union cpu_time_count old_expires, new_expires, val;
705         int ret;
706
707         if (unlikely(p == NULL)) {
708                 /*
709                  * Timer refers to a dead task's clock.
710                  */
711                 return -ESRCH;
712         }
713
714         new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
715
716         read_lock(&tasklist_lock);
717         /*
718          * We need the tasklist_lock to protect against reaping that
719          * clears p->signal.  If p has just been reaped, we can no
720          * longer get any information about it at all.
721          */
722         if (unlikely(p->signal == NULL)) {
723                 read_unlock(&tasklist_lock);
724                 put_task_struct(p);
725                 timer->it.cpu.task = NULL;
726                 return -ESRCH;
727         }
728
729         /*
730          * Disarm any old timer after extracting its expiry time.
731          */
732         BUG_ON(!irqs_disabled());
733         spin_lock(&p->sighand->siglock);
734         old_expires = timer->it.cpu.expires;
735         list_del_init(&timer->it.cpu.entry);
736         spin_unlock(&p->sighand->siglock);
737
738         /*
739          * We need to sample the current value to convert the new
740          * value from to relative and absolute, and to convert the
741          * old value from absolute to relative.  To set a process
742          * timer, we need a sample to balance the thread expiry
743          * times (in arm_timer).  With an absolute time, we must
744          * check if it's already passed.  In short, we need a sample.
745          */
746         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
747                 cpu_clock_sample(timer->it_clock, p, &val);
748         } else {
749                 cpu_clock_sample_group(timer->it_clock, p, &val);
750         }
751
752         if (old) {
753                 if (old_expires.sched == 0) {
754                         old->it_value.tv_sec = 0;
755                         old->it_value.tv_nsec = 0;
756                 } else {
757                         /*
758                          * Update the timer in case it has
759                          * overrun already.  If it has,
760                          * we'll report it as having overrun
761                          * and with the next reloaded timer
762                          * already ticking, though we are
763                          * swallowing that pending
764                          * notification here to install the
765                          * new setting.
766                          */
767                         bump_cpu_timer(timer, val);
768                         if (cpu_time_before(timer->it_clock, val,
769                                             timer->it.cpu.expires)) {
770                                 old_expires = cpu_time_sub(
771                                         timer->it_clock,
772                                         timer->it.cpu.expires, val);
773                                 sample_to_timespec(timer->it_clock,
774                                                    old_expires,
775                                                    &old->it_value);
776                         } else {
777                                 old->it_value.tv_nsec = 1;
778                                 old->it_value.tv_sec = 0;
779                         }
780                 }
781         }
782
783         if (unlikely(timer->it.cpu.firing)) {
784                 /*
785                  * We are colliding with the timer actually firing.
786                  * Punt after filling in the timer's old value, and
787                  * disable this firing since we are already reporting
788                  * it as an overrun (thanks to bump_cpu_timer above).
789                  */
790                 read_unlock(&tasklist_lock);
791                 timer->it.cpu.firing = -1;
792                 ret = TIMER_RETRY;
793                 goto out;
794         }
795
796         if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
797                 cpu_time_add(timer->it_clock, &new_expires, val);
798         }
799
800         /*
801          * Install the new expiry time (or zero).
802          * For a timer with no notification action, we don't actually
803          * arm the timer (we'll just fake it for timer_gettime).
804          */
805         timer->it.cpu.expires = new_expires;
806         if (new_expires.sched != 0 &&
807             (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
808             cpu_time_before(timer->it_clock, val, new_expires)) {
809                 arm_timer(timer, val);
810         }
811
812         read_unlock(&tasklist_lock);
813
814         /*
815          * Install the new reload setting, and
816          * set up the signal and overrun bookkeeping.
817          */
818         timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
819                                                 &new->it_interval);
820
821         /*
822          * This acts as a modification timestamp for the timer,
823          * so any automatic reload attempt will punt on seeing
824          * that we have reset the timer manually.
825          */
826         timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
827                 ~REQUEUE_PENDING;
828         timer->it_overrun_last = 0;
829         timer->it_overrun = -1;
830
831         if (new_expires.sched != 0 &&
832             (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
833             !cpu_time_before(timer->it_clock, val, new_expires)) {
834                 /*
835                  * The designated time already passed, so we notify
836                  * immediately, even if the thread never runs to
837                  * accumulate more time on this clock.
838                  */
839                 cpu_timer_fire(timer);
840         }
841
842         ret = 0;
843  out:
844         if (old) {
845                 sample_to_timespec(timer->it_clock,
846                                    timer->it.cpu.incr, &old->it_interval);
847         }
848         return ret;
849 }
850
851 void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
852 {
853         union cpu_time_count now;
854         struct task_struct *p = timer->it.cpu.task;
855         int clear_dead;
856
857         /*
858          * Easy part: convert the reload time.
859          */
860         sample_to_timespec(timer->it_clock,
861                            timer->it.cpu.incr, &itp->it_interval);
862
863         if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all.  */
864                 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
865                 return;
866         }
867
868         if (unlikely(p == NULL)) {
869                 /*
870                  * This task already died and the timer will never fire.
871                  * In this case, expires is actually the dead value.
872                  */
873         dead:
874                 sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
875                                    &itp->it_value);
876                 return;
877         }
878
879         /*
880          * Sample the clock to take the difference with the expiry time.
881          */
882         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
883                 cpu_clock_sample(timer->it_clock, p, &now);
884                 clear_dead = p->exit_state;
885         } else {
886                 read_lock(&tasklist_lock);
887                 if (unlikely(p->signal == NULL)) {
888                         /*
889                          * The process has been reaped.
890                          * We can't even collect a sample any more.
891                          * Call the timer disarmed, nothing else to do.
892                          */
893                         put_task_struct(p);
894                         timer->it.cpu.task = NULL;
895                         timer->it.cpu.expires.sched = 0;
896                         read_unlock(&tasklist_lock);
897                         goto dead;
898                 } else {
899                         cpu_clock_sample_group(timer->it_clock, p, &now);
900                         clear_dead = (unlikely(p->exit_state) &&
901                                       thread_group_empty(p));
902                 }
903                 read_unlock(&tasklist_lock);
904         }
905
906         if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
907                 if (timer->it.cpu.incr.sched == 0 &&
908                     cpu_time_before(timer->it_clock,
909                                     timer->it.cpu.expires, now)) {
910                         /*
911                          * Do-nothing timer expired and has no reload,
912                          * so it's as if it was never set.
913                          */
914                         timer->it.cpu.expires.sched = 0;
915                         itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
916                         return;
917                 }
918                 /*
919                  * Account for any expirations and reloads that should
920                  * have happened.
921                  */
922                 bump_cpu_timer(timer, now);
923         }
924
925         if (unlikely(clear_dead)) {
926                 /*
927                  * We've noticed that the thread is dead, but
928                  * not yet reaped.  Take this opportunity to
929                  * drop our task ref.
930                  */
931                 clear_dead_task(timer, now);
932                 goto dead;
933         }
934
935         if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
936                 sample_to_timespec(timer->it_clock,
937                                    cpu_time_sub(timer->it_clock,
938                                                 timer->it.cpu.expires, now),
939                                    &itp->it_value);
940         } else {
941                 /*
942                  * The timer should have expired already, but the firing
943                  * hasn't taken place yet.  Say it's just about to expire.
944                  */
945                 itp->it_value.tv_nsec = 1;
946                 itp->it_value.tv_sec = 0;
947         }
948 }
949
950 /*
951  * Check for any per-thread CPU timers that have fired and move them off
952  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
953  * tsk->it_*_expires values to reflect the remaining thread CPU timers.
954  */
955 static void check_thread_timers(struct task_struct *tsk,
956                                 struct list_head *firing)
957 {
958         int maxfire;
959         struct list_head *timers = tsk->cpu_timers;
960
961         maxfire = 20;
962         tsk->it_prof_expires = cputime_zero;
963         while (!list_empty(timers)) {
964                 struct cpu_timer_list *t = list_entry(timers->next,
965                                                       struct cpu_timer_list,
966                                                       entry);
967                 if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
968                         tsk->it_prof_expires = t->expires.cpu;
969                         break;
970                 }
971                 t->firing = 1;
972                 list_move_tail(&t->entry, firing);
973         }
974
975         ++timers;
976         maxfire = 20;
977         tsk->it_virt_expires = cputime_zero;
978         while (!list_empty(timers)) {
979                 struct cpu_timer_list *t = list_entry(timers->next,
980                                                       struct cpu_timer_list,
981                                                       entry);
982                 if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
983                         tsk->it_virt_expires = t->expires.cpu;
984                         break;
985                 }
986                 t->firing = 1;
987                 list_move_tail(&t->entry, firing);
988         }
989
990         ++timers;
991         maxfire = 20;
992         tsk->it_sched_expires = 0;
993         while (!list_empty(timers)) {
994                 struct cpu_timer_list *t = list_entry(timers->next,
995                                                       struct cpu_timer_list,
996                                                       entry);
997                 if (!--maxfire || tsk->sched_time < t->expires.sched) {
998                         tsk->it_sched_expires = t->expires.sched;
999                         break;
1000                 }
1001                 t->firing = 1;
1002                 list_move_tail(&t->entry, firing);
1003         }
1004 }
1005
1006 /*
1007  * Check for any per-thread CPU timers that have fired and move them
1008  * off the tsk->*_timers list onto the firing list.  Per-thread timers
1009  * have already been taken off.
1010  */
1011 static void check_process_timers(struct task_struct *tsk,
1012                                  struct list_head *firing)
1013 {
1014         int maxfire;
1015         struct signal_struct *const sig = tsk->signal;
1016         cputime_t utime, stime, ptime, virt_expires, prof_expires;
1017         unsigned long long sched_time, sched_expires;
1018         struct task_struct *t;
1019         struct list_head *timers = sig->cpu_timers;
1020
1021         /*
1022          * Don't sample the current process CPU clocks if there are no timers.
1023          */
1024         if (list_empty(&timers[CPUCLOCK_PROF]) &&
1025             cputime_eq(sig->it_prof_expires, cputime_zero) &&
1026             sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&
1027             list_empty(&timers[CPUCLOCK_VIRT]) &&
1028             cputime_eq(sig->it_virt_expires, cputime_zero) &&
1029             list_empty(&timers[CPUCLOCK_SCHED]))
1030                 return;
1031
1032         /*
1033          * Collect the current process totals.
1034          */
1035         utime = sig->utime;
1036         stime = sig->stime;
1037         sched_time = sig->sched_time;
1038         t = tsk;
1039         do {
1040                 utime = cputime_add(utime, t->utime);
1041                 stime = cputime_add(stime, t->stime);
1042                 sched_time += t->sched_time;
1043                 t = next_thread(t);
1044         } while (t != tsk);
1045         ptime = cputime_add(utime, stime);
1046
1047         maxfire = 20;
1048         prof_expires = cputime_zero;
1049         while (!list_empty(timers)) {
1050                 struct cpu_timer_list *t = list_entry(timers->next,
1051                                                       struct cpu_timer_list,
1052                                                       entry);
1053                 if (!--maxfire || cputime_lt(ptime, t->expires.cpu)) {
1054                         prof_expires = t->expires.cpu;
1055                         break;
1056                 }
1057                 t->firing = 1;
1058                 list_move_tail(&t->entry, firing);
1059         }
1060
1061         ++timers;
1062         maxfire = 20;
1063         virt_expires = cputime_zero;
1064         while (!list_empty(timers)) {
1065                 struct cpu_timer_list *t = list_entry(timers->next,
1066                                                       struct cpu_timer_list,
1067                                                       entry);
1068                 if (!--maxfire || cputime_lt(utime, t->expires.cpu)) {
1069                         virt_expires = t->expires.cpu;
1070                         break;
1071                 }
1072                 t->firing = 1;
1073                 list_move_tail(&t->entry, firing);
1074         }
1075
1076         ++timers;
1077         maxfire = 20;
1078         sched_expires = 0;
1079         while (!list_empty(timers)) {
1080                 struct cpu_timer_list *t = list_entry(timers->next,
1081                                                       struct cpu_timer_list,
1082                                                       entry);
1083                 if (!--maxfire || sched_time < t->expires.sched) {
1084                         sched_expires = t->expires.sched;
1085                         break;
1086                 }
1087                 t->firing = 1;
1088                 list_move_tail(&t->entry, firing);
1089         }
1090
1091         /*
1092          * Check for the special case process timers.
1093          */
1094         if (!cputime_eq(sig->it_prof_expires, cputime_zero)) {
1095                 if (cputime_ge(ptime, sig->it_prof_expires)) {
1096                         /* ITIMER_PROF fires and reloads.  */
1097                         sig->it_prof_expires = sig->it_prof_incr;
1098                         if (!cputime_eq(sig->it_prof_expires, cputime_zero)) {
1099                                 sig->it_prof_expires = cputime_add(
1100                                         sig->it_prof_expires, ptime);
1101                         }
1102                         __group_send_sig_info(SIGPROF, SEND_SIG_PRIV, tsk);
1103                 }
1104                 if (!cputime_eq(sig->it_prof_expires, cputime_zero) &&
1105                     (cputime_eq(prof_expires, cputime_zero) ||
1106                      cputime_lt(sig->it_prof_expires, prof_expires))) {
1107                         prof_expires = sig->it_prof_expires;
1108                 }
1109         }
1110         if (!cputime_eq(sig->it_virt_expires, cputime_zero)) {
1111                 if (cputime_ge(utime, sig->it_virt_expires)) {
1112                         /* ITIMER_VIRTUAL fires and reloads.  */
1113                         sig->it_virt_expires = sig->it_virt_incr;
1114                         if (!cputime_eq(sig->it_virt_expires, cputime_zero)) {
1115                                 sig->it_virt_expires = cputime_add(
1116                                         sig->it_virt_expires, utime);
1117                         }
1118                         __group_send_sig_info(SIGVTALRM, SEND_SIG_PRIV, tsk);
1119                 }
1120                 if (!cputime_eq(sig->it_virt_expires, cputime_zero) &&
1121                     (cputime_eq(virt_expires, cputime_zero) ||
1122                      cputime_lt(sig->it_virt_expires, virt_expires))) {
1123                         virt_expires = sig->it_virt_expires;
1124                 }
1125         }
1126         if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
1127                 unsigned long psecs = cputime_to_secs(ptime);
1128                 cputime_t x;
1129                 if (psecs >= sig->rlim[RLIMIT_CPU].rlim_max) {
1130                         /*
1131                          * At the hard limit, we just die.
1132                          * No need to calculate anything else now.
1133                          */
1134                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1135                         return;
1136                 }
1137                 if (psecs >= sig->rlim[RLIMIT_CPU].rlim_cur) {
1138                         /*
1139                          * At the soft limit, send a SIGXCPU every second.
1140                          */
1141                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1142                         if (sig->rlim[RLIMIT_CPU].rlim_cur
1143                             < sig->rlim[RLIMIT_CPU].rlim_max) {
1144                                 sig->rlim[RLIMIT_CPU].rlim_cur++;
1145                         }
1146                 }
1147                 x = secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
1148                 if (cputime_eq(prof_expires, cputime_zero) ||
1149                     cputime_lt(x, prof_expires)) {
1150                         prof_expires = x;
1151                 }
1152         }
1153
1154         if (!cputime_eq(prof_expires, cputime_zero) ||
1155             !cputime_eq(virt_expires, cputime_zero) ||
1156             sched_expires != 0) {
1157                 /*
1158                  * Rebalance the threads' expiry times for the remaining
1159                  * process CPU timers.
1160                  */
1161
1162                 cputime_t prof_left, virt_left, ticks;
1163                 unsigned long long sched_left, sched;
1164                 const unsigned int nthreads = atomic_read(&sig->live);
1165
1166                 if (!nthreads)
1167                         return;
1168
1169                 prof_left = cputime_sub(prof_expires, utime);
1170                 prof_left = cputime_sub(prof_left, stime);
1171                 prof_left = cputime_div(prof_left, nthreads);
1172                 virt_left = cputime_sub(virt_expires, utime);
1173                 virt_left = cputime_div(virt_left, nthreads);
1174                 if (sched_expires) {
1175                         sched_left = sched_expires - sched_time;
1176                         do_div(sched_left, nthreads);
1177                 } else {
1178                         sched_left = 0;
1179                 }
1180                 t = tsk;
1181                 do {
1182                         ticks = cputime_add(cputime_add(t->utime, t->stime),
1183                                             prof_left);
1184                         if (!cputime_eq(prof_expires, cputime_zero) &&
1185                             (cputime_eq(t->it_prof_expires, cputime_zero) ||
1186                              cputime_gt(t->it_prof_expires, ticks))) {
1187                                 t->it_prof_expires = ticks;
1188                         }
1189
1190                         ticks = cputime_add(t->utime, virt_left);
1191                         if (!cputime_eq(virt_expires, cputime_zero) &&
1192                             (cputime_eq(t->it_virt_expires, cputime_zero) ||
1193                              cputime_gt(t->it_virt_expires, ticks))) {
1194                                 t->it_virt_expires = ticks;
1195                         }
1196
1197                         sched = t->sched_time + sched_left;
1198                         if (sched_expires && (t->it_sched_expires == 0 ||
1199                                               t->it_sched_expires > sched)) {
1200                                 t->it_sched_expires = sched;
1201                         }
1202
1203                         do {
1204                                 t = next_thread(t);
1205                         } while (unlikely(t->exit_state));
1206                 } while (t != tsk);
1207         }
1208 }
1209
1210 /*
1211  * This is called from the signal code (via do_schedule_next_timer)
1212  * when the last timer signal was delivered and we have to reload the timer.
1213  */
1214 void posix_cpu_timer_schedule(struct k_itimer *timer)
1215 {
1216         struct task_struct *p = timer->it.cpu.task;
1217         union cpu_time_count now;
1218
1219         if (unlikely(p == NULL))
1220                 /*
1221                  * The task was cleaned up already, no future firings.
1222                  */
1223                 return;
1224
1225         /*
1226          * Fetch the current sample and update the timer's expiry time.
1227          */
1228         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1229                 cpu_clock_sample(timer->it_clock, p, &now);
1230                 bump_cpu_timer(timer, now);
1231                 if (unlikely(p->exit_state)) {
1232                         clear_dead_task(timer, now);
1233                         return;
1234                 }
1235                 read_lock(&tasklist_lock); /* arm_timer needs it.  */
1236         } else {
1237                 read_lock(&tasklist_lock);
1238                 if (unlikely(p->signal == NULL)) {
1239                         /*
1240                          * The process has been reaped.
1241                          * We can't even collect a sample any more.
1242                          */
1243                         put_task_struct(p);
1244                         timer->it.cpu.task = p = NULL;
1245                         timer->it.cpu.expires.sched = 0;
1246                         read_unlock(&tasklist_lock);
1247                         return;
1248                 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1249                         /*
1250                          * We've noticed that the thread is dead, but
1251                          * not yet reaped.  Take this opportunity to
1252                          * drop our task ref.
1253                          */
1254                         clear_dead_task(timer, now);
1255                         read_unlock(&tasklist_lock);
1256                         return;
1257                 }
1258                 cpu_clock_sample_group(timer->it_clock, p, &now);
1259                 bump_cpu_timer(timer, now);
1260                 /* Leave the tasklist_lock locked for the call below.  */
1261         }
1262
1263         /*
1264          * Now re-arm for the new expiry time.
1265          */
1266         arm_timer(timer, now);
1267
1268         read_unlock(&tasklist_lock);
1269 }
1270
1271 /*
1272  * This is called from the timer interrupt handler.  The irq handler has
1273  * already updated our counts.  We need to check if any timers fire now.
1274  * Interrupts are disabled.
1275  */
1276 void run_posix_cpu_timers(struct task_struct *tsk)
1277 {
1278         LIST_HEAD(firing);
1279         struct k_itimer *timer, *next;
1280
1281         BUG_ON(!irqs_disabled());
1282
1283 #define UNEXPIRED(clock) \
1284                 (cputime_eq(tsk->it_##clock##_expires, cputime_zero) || \
1285                  cputime_lt(clock##_ticks(tsk), tsk->it_##clock##_expires))
1286
1287         if (UNEXPIRED(prof) && UNEXPIRED(virt) &&
1288             (tsk->it_sched_expires == 0 ||
1289              tsk->sched_time < tsk->it_sched_expires))
1290                 return;
1291
1292 #undef  UNEXPIRED
1293
1294         /*
1295          * Double-check with locks held.
1296          */
1297         read_lock(&tasklist_lock);
1298         if (likely(tsk->signal != NULL)) {
1299                 spin_lock(&tsk->sighand->siglock);
1300
1301                 /*
1302                  * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N]
1303                  * all the timers that are firing, and put them on the firing list.
1304                  */
1305                 check_thread_timers(tsk, &firing);
1306                 check_process_timers(tsk, &firing);
1307
1308                 /*
1309                  * We must release these locks before taking any timer's lock.
1310                  * There is a potential race with timer deletion here, as the
1311                  * siglock now protects our private firing list.  We have set
1312                  * the firing flag in each timer, so that a deletion attempt
1313                  * that gets the timer lock before we do will give it up and
1314                  * spin until we've taken care of that timer below.
1315                  */
1316                 spin_unlock(&tsk->sighand->siglock);
1317         }
1318         read_unlock(&tasklist_lock);
1319
1320         /*
1321          * Now that all the timers on our list have the firing flag,
1322          * noone will touch their list entries but us.  We'll take
1323          * each timer's lock before clearing its firing flag, so no
1324          * timer call will interfere.
1325          */
1326         list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1327                 int firing;
1328                 spin_lock(&timer->it_lock);
1329                 list_del_init(&timer->it.cpu.entry);
1330                 firing = timer->it.cpu.firing;
1331                 timer->it.cpu.firing = 0;
1332                 /*
1333                  * The firing flag is -1 if we collided with a reset
1334                  * of the timer, which already reported this
1335                  * almost-firing as an overrun.  So don't generate an event.
1336                  */
1337                 if (likely(firing >= 0)) {
1338                         cpu_timer_fire(timer);
1339                 }
1340                 spin_unlock(&timer->it_lock);
1341         }
1342 }
1343
1344 /*
1345  * Set one of the process-wide special case CPU timers.
1346  * The tasklist_lock and tsk->sighand->siglock must be held by the caller.
1347  * The oldval argument is null for the RLIMIT_CPU timer, where *newval is
1348  * absolute; non-null for ITIMER_*, where *newval is relative and we update
1349  * it to be absolute, *oldval is absolute and we update it to be relative.
1350  */
1351 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1352                            cputime_t *newval, cputime_t *oldval)
1353 {
1354         union cpu_time_count now;
1355         struct list_head *head;
1356
1357         BUG_ON(clock_idx == CPUCLOCK_SCHED);
1358         cpu_clock_sample_group_locked(clock_idx, tsk, &now);
1359
1360         if (oldval) {
1361                 if (!cputime_eq(*oldval, cputime_zero)) {
1362                         if (cputime_le(*oldval, now.cpu)) {
1363                                 /* Just about to fire. */
1364                                 *oldval = jiffies_to_cputime(1);
1365                         } else {
1366                                 *oldval = cputime_sub(*oldval, now.cpu);
1367                         }
1368                 }
1369
1370                 if (cputime_eq(*newval, cputime_zero))
1371                         return;
1372                 *newval = cputime_add(*newval, now.cpu);
1373
1374                 /*
1375                  * If the RLIMIT_CPU timer will expire before the
1376                  * ITIMER_PROF timer, we have nothing else to do.
1377                  */
1378                 if (tsk->signal->rlim[RLIMIT_CPU].rlim_cur
1379                     < cputime_to_secs(*newval))
1380                         return;
1381         }
1382
1383         /*
1384          * Check whether there are any process timers already set to fire
1385          * before this one.  If so, we don't have anything more to do.
1386          */
1387         head = &tsk->signal->cpu_timers[clock_idx];
1388         if (list_empty(head) ||
1389             cputime_ge(list_entry(head->next,
1390                                   struct cpu_timer_list, entry)->expires.cpu,
1391                        *newval)) {
1392                 /*
1393                  * Rejigger each thread's expiry time so that one will
1394                  * notice before we hit the process-cumulative expiry time.
1395                  */
1396                 union cpu_time_count expires = { .sched = 0 };
1397                 expires.cpu = *newval;
1398                 process_timer_rebalance(tsk, clock_idx, expires, now);
1399         }
1400 }
1401
1402 static long posix_cpu_clock_nanosleep_restart(struct restart_block *);
1403
1404 int posix_cpu_nsleep(clockid_t which_clock, int flags,
1405                      struct timespec *rqtp)
1406 {
1407         struct restart_block *restart_block =
1408             &current_thread_info()->restart_block;
1409         struct k_itimer timer;
1410         int error;
1411
1412         /*
1413          * Diagnose required errors first.
1414          */
1415         if (CPUCLOCK_PERTHREAD(which_clock) &&
1416             (CPUCLOCK_PID(which_clock) == 0 ||
1417              CPUCLOCK_PID(which_clock) == current->pid))
1418                 return -EINVAL;
1419
1420         /*
1421          * Set up a temporary timer and then wait for it to go off.
1422          */
1423         memset(&timer, 0, sizeof timer);
1424         spin_lock_init(&timer.it_lock);
1425         timer.it_clock = which_clock;
1426         timer.it_overrun = -1;
1427         error = posix_cpu_timer_create(&timer);
1428         timer.it_process = current;
1429         if (!error) {
1430                 struct timespec __user *rmtp;
1431                 static struct itimerspec zero_it;
1432                 struct itimerspec it = { .it_value = *rqtp,
1433                                          .it_interval = {} };
1434
1435                 spin_lock_irq(&timer.it_lock);
1436                 error = posix_cpu_timer_set(&timer, flags, &it, NULL);
1437                 if (error) {
1438                         spin_unlock_irq(&timer.it_lock);
1439                         return error;
1440                 }
1441
1442                 while (!signal_pending(current)) {
1443                         if (timer.it.cpu.expires.sched == 0) {
1444                                 /*
1445                                  * Our timer fired and was reset.
1446                                  */
1447                                 spin_unlock_irq(&timer.it_lock);
1448                                 return 0;
1449                         }
1450
1451                         /*
1452                          * Block until cpu_timer_fire (or a signal) wakes us.
1453                          */
1454                         __set_current_state(TASK_INTERRUPTIBLE);
1455                         spin_unlock_irq(&timer.it_lock);
1456                         schedule();
1457                         spin_lock_irq(&timer.it_lock);
1458                 }
1459
1460                 /*
1461                  * We were interrupted by a signal.
1462                  */
1463                 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1464                 posix_cpu_timer_set(&timer, 0, &zero_it, &it);
1465                 spin_unlock_irq(&timer.it_lock);
1466
1467                 if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
1468                         /*
1469                          * It actually did fire already.
1470                          */
1471                         return 0;
1472                 }
1473
1474                 /*
1475                  * Report back to the user the time still remaining.
1476                  */
1477                 rmtp = (struct timespec __user *) restart_block->arg1;
1478                 if (rmtp != NULL && !(flags & TIMER_ABSTIME) &&
1479                     copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1480                         return -EFAULT;
1481
1482                 restart_block->fn = posix_cpu_clock_nanosleep_restart;
1483                 /* Caller already set restart_block->arg1 */
1484                 restart_block->arg0 = which_clock;
1485                 restart_block->arg2 = rqtp->tv_sec;
1486                 restart_block->arg3 = rqtp->tv_nsec;
1487
1488                 error = -ERESTART_RESTARTBLOCK;
1489         }
1490
1491         return error;
1492 }
1493
1494 static long
1495 posix_cpu_clock_nanosleep_restart(struct restart_block *restart_block)
1496 {
1497         clockid_t which_clock = restart_block->arg0;
1498         struct timespec t = { .tv_sec = restart_block->arg2,
1499                               .tv_nsec = restart_block->arg3 };
1500         restart_block->fn = do_no_restart_syscall;
1501         return posix_cpu_nsleep(which_clock, TIMER_ABSTIME, &t);
1502 }
1503
1504
1505 #define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1506 #define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1507
1508 static int process_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
1509 {
1510         return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1511 }
1512 static int process_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
1513 {
1514         return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1515 }
1516 static int process_cpu_timer_create(struct k_itimer *timer)
1517 {
1518         timer->it_clock = PROCESS_CLOCK;
1519         return posix_cpu_timer_create(timer);
1520 }
1521 static int process_cpu_nsleep(clockid_t which_clock, int flags,
1522                               struct timespec *rqtp)
1523 {
1524         return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp);
1525 }
1526 static int thread_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
1527 {
1528         return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1529 }
1530 static int thread_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
1531 {
1532         return posix_cpu_clock_get(THREAD_CLOCK, tp);
1533 }
1534 static int thread_cpu_timer_create(struct k_itimer *timer)
1535 {
1536         timer->it_clock = THREAD_CLOCK;
1537         return posix_cpu_timer_create(timer);
1538 }
1539 static int thread_cpu_nsleep(clockid_t which_clock, int flags,
1540                               struct timespec *rqtp)
1541 {
1542         return -EINVAL;
1543 }
1544
1545 static __init int init_posix_cpu_timers(void)
1546 {
1547         struct k_clock process = {
1548                 .clock_getres = process_cpu_clock_getres,
1549                 .clock_get = process_cpu_clock_get,
1550                 .clock_set = do_posix_clock_nosettime,
1551                 .timer_create = process_cpu_timer_create,
1552                 .nsleep = process_cpu_nsleep,
1553         };
1554         struct k_clock thread = {
1555                 .clock_getres = thread_cpu_clock_getres,
1556                 .clock_get = thread_cpu_clock_get,
1557                 .clock_set = do_posix_clock_nosettime,
1558                 .timer_create = thread_cpu_timer_create,
1559                 .nsleep = thread_cpu_nsleep,
1560         };
1561
1562         register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1563         register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1564
1565         return 0;
1566 }
1567 __initcall(init_posix_cpu_timers);