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