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Source at commit be977234bfb4a6dca8a39e7c52165e4cd536ad71 created 12 years 9 months ago. By Lars-Peter Clausen, jz4740: Fix compile error | |
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1 | /* |
2 | * Implement CPU time clocks for the POSIX clock interface. |
3 | */ |
4 | |
5 | #include <linux/sched.h> |
6 | #include <linux/posix-timers.h> |
7 | #include <linux/errno.h> |
8 | #include <linux/math64.h> |
9 | #include <asm/uaccess.h> |
10 | #include <linux/kernel_stat.h> |
11 | #include <trace/events/timer.h> |
12 | |
13 | /* |
14 | * Called after updating RLIMIT_CPU to run cpu timer and update |
15 | * tsk->signal->cputime_expires expiration cache if necessary. Needs |
16 | * siglock protection since other code may update expiration cache as |
17 | * well. |
18 | */ |
19 | void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new) |
20 | { |
21 | cputime_t cputime = secs_to_cputime(rlim_new); |
22 | |
23 | spin_lock_irq(&task->sighand->siglock); |
24 | set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL); |
25 | spin_unlock_irq(&task->sighand->siglock); |
26 | } |
27 | |
28 | static int check_clock(const clockid_t which_clock) |
29 | { |
30 | int error = 0; |
31 | struct task_struct *p; |
32 | const pid_t pid = CPUCLOCK_PID(which_clock); |
33 | |
34 | if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX) |
35 | return -EINVAL; |
36 | |
37 | if (pid == 0) |
38 | return 0; |
39 | |
40 | rcu_read_lock(); |
41 | p = find_task_by_vpid(pid); |
42 | if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ? |
43 | same_thread_group(p, current) : has_group_leader_pid(p))) { |
44 | error = -EINVAL; |
45 | } |
46 | rcu_read_unlock(); |
47 | |
48 | return error; |
49 | } |
50 | |
51 | static inline union cpu_time_count |
52 | timespec_to_sample(const clockid_t which_clock, const struct timespec *tp) |
53 | { |
54 | union cpu_time_count ret; |
55 | ret.sched = 0; /* high half always zero when .cpu used */ |
56 | if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { |
57 | ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec; |
58 | } else { |
59 | ret.cpu = timespec_to_cputime(tp); |
60 | } |
61 | return ret; |
62 | } |
63 | |
64 | static void sample_to_timespec(const clockid_t which_clock, |
65 | union cpu_time_count cpu, |
66 | struct timespec *tp) |
67 | { |
68 | if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) |
69 | *tp = ns_to_timespec(cpu.sched); |
70 | else |
71 | cputime_to_timespec(cpu.cpu, tp); |
72 | } |
73 | |
74 | static inline int cpu_time_before(const clockid_t which_clock, |
75 | union cpu_time_count now, |
76 | union cpu_time_count then) |
77 | { |
78 | if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { |
79 | return now.sched < then.sched; |
80 | } else { |
81 | return cputime_lt(now.cpu, then.cpu); |
82 | } |
83 | } |
84 | static inline void cpu_time_add(const clockid_t which_clock, |
85 | union cpu_time_count *acc, |
86 | union cpu_time_count val) |
87 | { |
88 | if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { |
89 | acc->sched += val.sched; |
90 | } else { |
91 | acc->cpu = cputime_add(acc->cpu, val.cpu); |
92 | } |
93 | } |
94 | static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock, |
95 | union cpu_time_count a, |
96 | union cpu_time_count b) |
97 | { |
98 | if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { |
99 | a.sched -= b.sched; |
100 | } else { |
101 | a.cpu = cputime_sub(a.cpu, b.cpu); |
102 | } |
103 | return a; |
104 | } |
105 | |
106 | /* |
107 | * Divide and limit the result to res >= 1 |
108 | * |
109 | * This is necessary to prevent signal delivery starvation, when the result of |
110 | * the division would be rounded down to 0. |
111 | */ |
112 | static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div) |
113 | { |
114 | cputime_t res = cputime_div(time, div); |
115 | |
116 | return max_t(cputime_t, res, 1); |
117 | } |
118 | |
119 | /* |
120 | * Update expiry time from increment, and increase overrun count, |
121 | * given the current clock sample. |
122 | */ |
123 | static void bump_cpu_timer(struct k_itimer *timer, |
124 | union cpu_time_count now) |
125 | { |
126 | int i; |
127 | |
128 | if (timer->it.cpu.incr.sched == 0) |
129 | return; |
130 | |
131 | if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) { |
132 | unsigned long long delta, incr; |
133 | |
134 | if (now.sched < timer->it.cpu.expires.sched) |
135 | return; |
136 | incr = timer->it.cpu.incr.sched; |
137 | delta = now.sched + incr - timer->it.cpu.expires.sched; |
138 | /* Don't use (incr*2 < delta), incr*2 might overflow. */ |
139 | for (i = 0; incr < delta - incr; i++) |
140 | incr = incr << 1; |
141 | for (; i >= 0; incr >>= 1, i--) { |
142 | if (delta < incr) |
143 | continue; |
144 | timer->it.cpu.expires.sched += incr; |
145 | timer->it_overrun += 1 << i; |
146 | delta -= incr; |
147 | } |
148 | } else { |
149 | cputime_t delta, incr; |
150 | |
151 | if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu)) |
152 | return; |
153 | incr = timer->it.cpu.incr.cpu; |
154 | delta = cputime_sub(cputime_add(now.cpu, incr), |
155 | timer->it.cpu.expires.cpu); |
156 | /* Don't use (incr*2 < delta), incr*2 might overflow. */ |
157 | for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++) |
158 | incr = cputime_add(incr, incr); |
159 | for (; i >= 0; incr = cputime_halve(incr), i--) { |
160 | if (cputime_lt(delta, incr)) |
161 | continue; |
162 | timer->it.cpu.expires.cpu = |
163 | cputime_add(timer->it.cpu.expires.cpu, incr); |
164 | timer->it_overrun += 1 << i; |
165 | delta = cputime_sub(delta, incr); |
166 | } |
167 | } |
168 | } |
169 | |
170 | static inline cputime_t prof_ticks(struct task_struct *p) |
171 | { |
172 | return cputime_add(p->utime, p->stime); |
173 | } |
174 | static inline cputime_t virt_ticks(struct task_struct *p) |
175 | { |
176 | return p->utime; |
177 | } |
178 | |
179 | static int |
180 | posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp) |
181 | { |
182 | int error = check_clock(which_clock); |
183 | if (!error) { |
184 | tp->tv_sec = 0; |
185 | tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ); |
186 | if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { |
187 | /* |
188 | * If sched_clock is using a cycle counter, we |
189 | * don't have any idea of its true resolution |
190 | * exported, but it is much more than 1s/HZ. |
191 | */ |
192 | tp->tv_nsec = 1; |
193 | } |
194 | } |
195 | return error; |
196 | } |
197 | |
198 | static int |
199 | posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp) |
200 | { |
201 | /* |
202 | * You can never reset a CPU clock, but we check for other errors |
203 | * in the call before failing with EPERM. |
204 | */ |
205 | int error = check_clock(which_clock); |
206 | if (error == 0) { |
207 | error = -EPERM; |
208 | } |
209 | return error; |
210 | } |
211 | |
212 | |
213 | /* |
214 | * Sample a per-thread clock for the given task. |
215 | */ |
216 | static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p, |
217 | union cpu_time_count *cpu) |
218 | { |
219 | switch (CPUCLOCK_WHICH(which_clock)) { |
220 | default: |
221 | return -EINVAL; |
222 | case CPUCLOCK_PROF: |
223 | cpu->cpu = prof_ticks(p); |
224 | break; |
225 | case CPUCLOCK_VIRT: |
226 | cpu->cpu = virt_ticks(p); |
227 | break; |
228 | case CPUCLOCK_SCHED: |
229 | cpu->sched = task_sched_runtime(p); |
230 | break; |
231 | } |
232 | return 0; |
233 | } |
234 | |
235 | void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times) |
236 | { |
237 | struct signal_struct *sig = tsk->signal; |
238 | struct task_struct *t; |
239 | |
240 | times->utime = sig->utime; |
241 | times->stime = sig->stime; |
242 | times->sum_exec_runtime = sig->sum_sched_runtime; |
243 | |
244 | rcu_read_lock(); |
245 | /* make sure we can trust tsk->thread_group list */ |
246 | if (!likely(pid_alive(tsk))) |
247 | goto out; |
248 | |
249 | t = tsk; |
250 | do { |
251 | times->utime = cputime_add(times->utime, t->utime); |
252 | times->stime = cputime_add(times->stime, t->stime); |
253 | times->sum_exec_runtime += t->se.sum_exec_runtime; |
254 | } while_each_thread(tsk, t); |
255 | out: |
256 | rcu_read_unlock(); |
257 | } |
258 | |
259 | static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b) |
260 | { |
261 | if (cputime_gt(b->utime, a->utime)) |
262 | a->utime = b->utime; |
263 | |
264 | if (cputime_gt(b->stime, a->stime)) |
265 | a->stime = b->stime; |
266 | |
267 | if (b->sum_exec_runtime > a->sum_exec_runtime) |
268 | a->sum_exec_runtime = b->sum_exec_runtime; |
269 | } |
270 | |
271 | void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) |
272 | { |
273 | struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; |
274 | struct task_cputime sum; |
275 | unsigned long flags; |
276 | |
277 | spin_lock_irqsave(&cputimer->lock, flags); |
278 | if (!cputimer->running) { |
279 | cputimer->running = 1; |
280 | /* |
281 | * The POSIX timer interface allows for absolute time expiry |
282 | * values through the TIMER_ABSTIME flag, therefore we have |
283 | * to synchronize the timer to the clock every time we start |
284 | * it. |
285 | */ |
286 | thread_group_cputime(tsk, &sum); |
287 | update_gt_cputime(&cputimer->cputime, &sum); |
288 | } |
289 | *times = cputimer->cputime; |
290 | spin_unlock_irqrestore(&cputimer->lock, flags); |
291 | } |
292 | |
293 | /* |
294 | * Sample a process (thread group) clock for the given group_leader task. |
295 | * Must be called with tasklist_lock held for reading. |
296 | */ |
297 | static int cpu_clock_sample_group(const clockid_t which_clock, |
298 | struct task_struct *p, |
299 | union cpu_time_count *cpu) |
300 | { |
301 | struct task_cputime cputime; |
302 | |
303 | switch (CPUCLOCK_WHICH(which_clock)) { |
304 | default: |
305 | return -EINVAL; |
306 | case CPUCLOCK_PROF: |
307 | thread_group_cputime(p, &cputime); |
308 | cpu->cpu = cputime_add(cputime.utime, cputime.stime); |
309 | break; |
310 | case CPUCLOCK_VIRT: |
311 | thread_group_cputime(p, &cputime); |
312 | cpu->cpu = cputime.utime; |
313 | break; |
314 | case CPUCLOCK_SCHED: |
315 | cpu->sched = thread_group_sched_runtime(p); |
316 | break; |
317 | } |
318 | return 0; |
319 | } |
320 | |
321 | |
322 | static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp) |
323 | { |
324 | const pid_t pid = CPUCLOCK_PID(which_clock); |
325 | int error = -EINVAL; |
326 | union cpu_time_count rtn; |
327 | |
328 | if (pid == 0) { |
329 | /* |
330 | * Special case constant value for our own clocks. |
331 | * We don't have to do any lookup to find ourselves. |
332 | */ |
333 | if (CPUCLOCK_PERTHREAD(which_clock)) { |
334 | /* |
335 | * Sampling just ourselves we can do with no locking. |
336 | */ |
337 | error = cpu_clock_sample(which_clock, |
338 | current, &rtn); |
339 | } else { |
340 | read_lock(&tasklist_lock); |
341 | error = cpu_clock_sample_group(which_clock, |
342 | current, &rtn); |
343 | read_unlock(&tasklist_lock); |
344 | } |
345 | } else { |
346 | /* |
347 | * Find the given PID, and validate that the caller |
348 | * should be able to see it. |
349 | */ |
350 | struct task_struct *p; |
351 | rcu_read_lock(); |
352 | p = find_task_by_vpid(pid); |
353 | if (p) { |
354 | if (CPUCLOCK_PERTHREAD(which_clock)) { |
355 | if (same_thread_group(p, current)) { |
356 | error = cpu_clock_sample(which_clock, |
357 | p, &rtn); |
358 | } |
359 | } else { |
360 | read_lock(&tasklist_lock); |
361 | if (thread_group_leader(p) && p->sighand) { |
362 | error = |
363 | cpu_clock_sample_group(which_clock, |
364 | p, &rtn); |
365 | } |
366 | read_unlock(&tasklist_lock); |
367 | } |
368 | } |
369 | rcu_read_unlock(); |
370 | } |
371 | |
372 | if (error) |
373 | return error; |
374 | sample_to_timespec(which_clock, rtn, tp); |
375 | return 0; |
376 | } |
377 | |
378 | |
379 | /* |
380 | * Validate the clockid_t for a new CPU-clock timer, and initialize the timer. |
381 | * This is called from sys_timer_create() and do_cpu_nanosleep() with the |
382 | * new timer already all-zeros initialized. |
383 | */ |
384 | static int posix_cpu_timer_create(struct k_itimer *new_timer) |
385 | { |
386 | int ret = 0; |
387 | const pid_t pid = CPUCLOCK_PID(new_timer->it_clock); |
388 | struct task_struct *p; |
389 | |
390 | if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX) |
391 | return -EINVAL; |
392 | |
393 | INIT_LIST_HEAD(&new_timer->it.cpu.entry); |
394 | |
395 | rcu_read_lock(); |
396 | if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) { |
397 | if (pid == 0) { |
398 | p = current; |
399 | } else { |
400 | p = find_task_by_vpid(pid); |
401 | if (p && !same_thread_group(p, current)) |
402 | p = NULL; |
403 | } |
404 | } else { |
405 | if (pid == 0) { |
406 | p = current->group_leader; |
407 | } else { |
408 | p = find_task_by_vpid(pid); |
409 | if (p && !has_group_leader_pid(p)) |
410 | p = NULL; |
411 | } |
412 | } |
413 | new_timer->it.cpu.task = p; |
414 | if (p) { |
415 | get_task_struct(p); |
416 | } else { |
417 | ret = -EINVAL; |
418 | } |
419 | rcu_read_unlock(); |
420 | |
421 | return ret; |
422 | } |
423 | |
424 | /* |
425 | * Clean up a CPU-clock timer that is about to be destroyed. |
426 | * This is called from timer deletion with the timer already locked. |
427 | * If we return TIMER_RETRY, it's necessary to release the timer's lock |
428 | * and try again. (This happens when the timer is in the middle of firing.) |
429 | */ |
430 | static int posix_cpu_timer_del(struct k_itimer *timer) |
431 | { |
432 | struct task_struct *p = timer->it.cpu.task; |
433 | int ret = 0; |
434 | |
435 | if (likely(p != NULL)) { |
436 | read_lock(&tasklist_lock); |
437 | if (unlikely(p->sighand == NULL)) { |
438 | /* |
439 | * We raced with the reaping of the task. |
440 | * The deletion should have cleared us off the list. |
441 | */ |
442 | BUG_ON(!list_empty(&timer->it.cpu.entry)); |
443 | } else { |
444 | spin_lock(&p->sighand->siglock); |
445 | if (timer->it.cpu.firing) |
446 | ret = TIMER_RETRY; |
447 | else |
448 | list_del(&timer->it.cpu.entry); |
449 | spin_unlock(&p->sighand->siglock); |
450 | } |
451 | read_unlock(&tasklist_lock); |
452 | |
453 | if (!ret) |
454 | put_task_struct(p); |
455 | } |
456 | |
457 | return ret; |
458 | } |
459 | |
460 | /* |
461 | * Clean out CPU timers still ticking when a thread exited. The task |
462 | * pointer is cleared, and the expiry time is replaced with the residual |
463 | * time for later timer_gettime calls to return. |
464 | * This must be called with the siglock held. |
465 | */ |
466 | static void cleanup_timers(struct list_head *head, |
467 | cputime_t utime, cputime_t stime, |
468 | unsigned long long sum_exec_runtime) |
469 | { |
470 | struct cpu_timer_list *timer, *next; |
471 | cputime_t ptime = cputime_add(utime, stime); |
472 | |
473 | list_for_each_entry_safe(timer, next, head, entry) { |
474 | list_del_init(&timer->entry); |
475 | if (cputime_lt(timer->expires.cpu, ptime)) { |
476 | timer->expires.cpu = cputime_zero; |
477 | } else { |
478 | timer->expires.cpu = cputime_sub(timer->expires.cpu, |
479 | ptime); |
480 | } |
481 | } |
482 | |
483 | ++head; |
484 | list_for_each_entry_safe(timer, next, head, entry) { |
485 | list_del_init(&timer->entry); |
486 | if (cputime_lt(timer->expires.cpu, utime)) { |
487 | timer->expires.cpu = cputime_zero; |
488 | } else { |
489 | timer->expires.cpu = cputime_sub(timer->expires.cpu, |
490 | utime); |
491 | } |
492 | } |
493 | |
494 | ++head; |
495 | list_for_each_entry_safe(timer, next, head, entry) { |
496 | list_del_init(&timer->entry); |
497 | if (timer->expires.sched < sum_exec_runtime) { |
498 | timer->expires.sched = 0; |
499 | } else { |
500 | timer->expires.sched -= sum_exec_runtime; |
501 | } |
502 | } |
503 | } |
504 | |
505 | /* |
506 | * These are both called with the siglock held, when the current thread |
507 | * is being reaped. When the final (leader) thread in the group is reaped, |
508 | * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit. |
509 | */ |
510 | void posix_cpu_timers_exit(struct task_struct *tsk) |
511 | { |
512 | cleanup_timers(tsk->cpu_timers, |
513 | tsk->utime, tsk->stime, tsk->se.sum_exec_runtime); |
514 | |
515 | } |
516 | void posix_cpu_timers_exit_group(struct task_struct *tsk) |
517 | { |
518 | struct signal_struct *const sig = tsk->signal; |
519 | |
520 | cleanup_timers(tsk->signal->cpu_timers, |
521 | cputime_add(tsk->utime, sig->utime), |
522 | cputime_add(tsk->stime, sig->stime), |
523 | tsk->se.sum_exec_runtime + sig->sum_sched_runtime); |
524 | } |
525 | |
526 | static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now) |
527 | { |
528 | /* |
529 | * That's all for this thread or process. |
530 | * We leave our residual in expires to be reported. |
531 | */ |
532 | put_task_struct(timer->it.cpu.task); |
533 | timer->it.cpu.task = NULL; |
534 | timer->it.cpu.expires = cpu_time_sub(timer->it_clock, |
535 | timer->it.cpu.expires, |
536 | now); |
537 | } |
538 | |
539 | static inline int expires_gt(cputime_t expires, cputime_t new_exp) |
540 | { |
541 | return cputime_eq(expires, cputime_zero) || |
542 | cputime_gt(expires, new_exp); |
543 | } |
544 | |
545 | /* |
546 | * Insert the timer on the appropriate list before any timers that |
547 | * expire later. This must be called with the tasklist_lock held |
548 | * for reading, interrupts disabled and p->sighand->siglock taken. |
549 | */ |
550 | static void arm_timer(struct k_itimer *timer) |
551 | { |
552 | struct task_struct *p = timer->it.cpu.task; |
553 | struct list_head *head, *listpos; |
554 | struct task_cputime *cputime_expires; |
555 | struct cpu_timer_list *const nt = &timer->it.cpu; |
556 | struct cpu_timer_list *next; |
557 | |
558 | if (CPUCLOCK_PERTHREAD(timer->it_clock)) { |
559 | head = p->cpu_timers; |
560 | cputime_expires = &p->cputime_expires; |
561 | } else { |
562 | head = p->signal->cpu_timers; |
563 | cputime_expires = &p->signal->cputime_expires; |
564 | } |
565 | head += CPUCLOCK_WHICH(timer->it_clock); |
566 | |
567 | listpos = head; |
568 | list_for_each_entry(next, head, entry) { |
569 | if (cpu_time_before(timer->it_clock, nt->expires, next->expires)) |
570 | break; |
571 | listpos = &next->entry; |
572 | } |
573 | list_add(&nt->entry, listpos); |
574 | |
575 | if (listpos == head) { |
576 | union cpu_time_count *exp = &nt->expires; |
577 | |
578 | /* |
579 | * We are the new earliest-expiring POSIX 1.b timer, hence |
580 | * need to update expiration cache. Take into account that |
581 | * for process timers we share expiration cache with itimers |
582 | * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME. |
583 | */ |
584 | |
585 | switch (CPUCLOCK_WHICH(timer->it_clock)) { |
586 | case CPUCLOCK_PROF: |
587 | if (expires_gt(cputime_expires->prof_exp, exp->cpu)) |
588 | cputime_expires->prof_exp = exp->cpu; |
589 | break; |
590 | case CPUCLOCK_VIRT: |
591 | if (expires_gt(cputime_expires->virt_exp, exp->cpu)) |
592 | cputime_expires->virt_exp = exp->cpu; |
593 | break; |
594 | case CPUCLOCK_SCHED: |
595 | if (cputime_expires->sched_exp == 0 || |
596 | cputime_expires->sched_exp > exp->sched) |
597 | cputime_expires->sched_exp = exp->sched; |
598 | break; |
599 | } |
600 | } |
601 | } |
602 | |
603 | /* |
604 | * The timer is locked, fire it and arrange for its reload. |
605 | */ |
606 | static void cpu_timer_fire(struct k_itimer *timer) |
607 | { |
608 | if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) { |
609 | /* |
610 | * User don't want any signal. |
611 | */ |
612 | timer->it.cpu.expires.sched = 0; |
613 | } else if (unlikely(timer->sigq == NULL)) { |
614 | /* |
615 | * This a special case for clock_nanosleep, |
616 | * not a normal timer from sys_timer_create. |
617 | */ |
618 | wake_up_process(timer->it_process); |
619 | timer->it.cpu.expires.sched = 0; |
620 | } else if (timer->it.cpu.incr.sched == 0) { |
621 | /* |
622 | * One-shot timer. Clear it as soon as it's fired. |
623 | */ |
624 | posix_timer_event(timer, 0); |
625 | timer->it.cpu.expires.sched = 0; |
626 | } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) { |
627 | /* |
628 | * The signal did not get queued because the signal |
629 | * was ignored, so we won't get any callback to |
630 | * reload the timer. But we need to keep it |
631 | * ticking in case the signal is deliverable next time. |
632 | */ |
633 | posix_cpu_timer_schedule(timer); |
634 | } |
635 | } |
636 | |
637 | /* |
638 | * Sample a process (thread group) timer for the given group_leader task. |
639 | * Must be called with tasklist_lock held for reading. |
640 | */ |
641 | static int cpu_timer_sample_group(const clockid_t which_clock, |
642 | struct task_struct *p, |
643 | union cpu_time_count *cpu) |
644 | { |
645 | struct task_cputime cputime; |
646 | |
647 | thread_group_cputimer(p, &cputime); |
648 | switch (CPUCLOCK_WHICH(which_clock)) { |
649 | default: |
650 | return -EINVAL; |
651 | case CPUCLOCK_PROF: |
652 | cpu->cpu = cputime_add(cputime.utime, cputime.stime); |
653 | break; |
654 | case CPUCLOCK_VIRT: |
655 | cpu->cpu = cputime.utime; |
656 | break; |
657 | case CPUCLOCK_SCHED: |
658 | cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p); |
659 | break; |
660 | } |
661 | return 0; |
662 | } |
663 | |
664 | /* |
665 | * Guts of sys_timer_settime for CPU timers. |
666 | * This is called with the timer locked and interrupts disabled. |
667 | * If we return TIMER_RETRY, it's necessary to release the timer's lock |
668 | * and try again. (This happens when the timer is in the middle of firing.) |
669 | */ |
670 | static int posix_cpu_timer_set(struct k_itimer *timer, int flags, |
671 | struct itimerspec *new, struct itimerspec *old) |
672 | { |
673 | struct task_struct *p = timer->it.cpu.task; |
674 | union cpu_time_count old_expires, new_expires, old_incr, val; |
675 | int ret; |
676 | |
677 | if (unlikely(p == NULL)) { |
678 | /* |
679 | * Timer refers to a dead task's clock. |
680 | */ |
681 | return -ESRCH; |
682 | } |
683 | |
684 | new_expires = timespec_to_sample(timer->it_clock, &new->it_value); |
685 | |
686 | read_lock(&tasklist_lock); |
687 | /* |
688 | * We need the tasklist_lock to protect against reaping that |
689 | * clears p->sighand. If p has just been reaped, we can no |
690 | * longer get any information about it at all. |
691 | */ |
692 | if (unlikely(p->sighand == NULL)) { |
693 | read_unlock(&tasklist_lock); |
694 | put_task_struct(p); |
695 | timer->it.cpu.task = NULL; |
696 | return -ESRCH; |
697 | } |
698 | |
699 | /* |
700 | * Disarm any old timer after extracting its expiry time. |
701 | */ |
702 | BUG_ON(!irqs_disabled()); |
703 | |
704 | ret = 0; |
705 | old_incr = timer->it.cpu.incr; |
706 | spin_lock(&p->sighand->siglock); |
707 | old_expires = timer->it.cpu.expires; |
708 | if (unlikely(timer->it.cpu.firing)) { |
709 | timer->it.cpu.firing = -1; |
710 | ret = TIMER_RETRY; |
711 | } else |
712 | list_del_init(&timer->it.cpu.entry); |
713 | |
714 | /* |
715 | * We need to sample the current value to convert the new |
716 | * value from to relative and absolute, and to convert the |
717 | * old value from absolute to relative. To set a process |
718 | * timer, we need a sample to balance the thread expiry |
719 | * times (in arm_timer). With an absolute time, we must |
720 | * check if it's already passed. In short, we need a sample. |
721 | */ |
722 | if (CPUCLOCK_PERTHREAD(timer->it_clock)) { |
723 | cpu_clock_sample(timer->it_clock, p, &val); |
724 | } else { |
725 | cpu_timer_sample_group(timer->it_clock, p, &val); |
726 | } |
727 | |
728 | if (old) { |
729 | if (old_expires.sched == 0) { |
730 | old->it_value.tv_sec = 0; |
731 | old->it_value.tv_nsec = 0; |
732 | } else { |
733 | /* |
734 | * Update the timer in case it has |
735 | * overrun already. If it has, |
736 | * we'll report it as having overrun |
737 | * and with the next reloaded timer |
738 | * already ticking, though we are |
739 | * swallowing that pending |
740 | * notification here to install the |
741 | * new setting. |
742 | */ |
743 | bump_cpu_timer(timer, val); |
744 | if (cpu_time_before(timer->it_clock, val, |
745 | timer->it.cpu.expires)) { |
746 | old_expires = cpu_time_sub( |
747 | timer->it_clock, |
748 | timer->it.cpu.expires, val); |
749 | sample_to_timespec(timer->it_clock, |
750 | old_expires, |
751 | &old->it_value); |
752 | } else { |
753 | old->it_value.tv_nsec = 1; |
754 | old->it_value.tv_sec = 0; |
755 | } |
756 | } |
757 | } |
758 | |
759 | if (unlikely(ret)) { |
760 | /* |
761 | * We are colliding with the timer actually firing. |
762 | * Punt after filling in the timer's old value, and |
763 | * disable this firing since we are already reporting |
764 | * it as an overrun (thanks to bump_cpu_timer above). |
765 | */ |
766 | spin_unlock(&p->sighand->siglock); |
767 | read_unlock(&tasklist_lock); |
768 | goto out; |
769 | } |
770 | |
771 | if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) { |
772 | cpu_time_add(timer->it_clock, &new_expires, val); |
773 | } |
774 | |
775 | /* |
776 | * Install the new expiry time (or zero). |
777 | * For a timer with no notification action, we don't actually |
778 | * arm the timer (we'll just fake it for timer_gettime). |
779 | */ |
780 | timer->it.cpu.expires = new_expires; |
781 | if (new_expires.sched != 0 && |
782 | cpu_time_before(timer->it_clock, val, new_expires)) { |
783 | arm_timer(timer); |
784 | } |
785 | |
786 | spin_unlock(&p->sighand->siglock); |
787 | read_unlock(&tasklist_lock); |
788 | |
789 | /* |
790 | * Install the new reload setting, and |
791 | * set up the signal and overrun bookkeeping. |
792 | */ |
793 | timer->it.cpu.incr = timespec_to_sample(timer->it_clock, |
794 | &new->it_interval); |
795 | |
796 | /* |
797 | * This acts as a modification timestamp for the timer, |
798 | * so any automatic reload attempt will punt on seeing |
799 | * that we have reset the timer manually. |
800 | */ |
801 | timer->it_requeue_pending = (timer->it_requeue_pending + 2) & |
802 | ~REQUEUE_PENDING; |
803 | timer->it_overrun_last = 0; |
804 | timer->it_overrun = -1; |
805 | |
806 | if (new_expires.sched != 0 && |
807 | !cpu_time_before(timer->it_clock, val, new_expires)) { |
808 | /* |
809 | * The designated time already passed, so we notify |
810 | * immediately, even if the thread never runs to |
811 | * accumulate more time on this clock. |
812 | */ |
813 | cpu_timer_fire(timer); |
814 | } |
815 | |
816 | ret = 0; |
817 | out: |
818 | if (old) { |
819 | sample_to_timespec(timer->it_clock, |
820 | old_incr, &old->it_interval); |
821 | } |
822 | return ret; |
823 | } |
824 | |
825 | static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp) |
826 | { |
827 | union cpu_time_count now; |
828 | struct task_struct *p = timer->it.cpu.task; |
829 | int clear_dead; |
830 | |
831 | /* |
832 | * Easy part: convert the reload time. |
833 | */ |
834 | sample_to_timespec(timer->it_clock, |
835 | timer->it.cpu.incr, &itp->it_interval); |
836 | |
837 | if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all. */ |
838 | itp->it_value.tv_sec = itp->it_value.tv_nsec = 0; |
839 | return; |
840 | } |
841 | |
842 | if (unlikely(p == NULL)) { |
843 | /* |
844 | * This task already died and the timer will never fire. |
845 | * In this case, expires is actually the dead value. |
846 | */ |
847 | dead: |
848 | sample_to_timespec(timer->it_clock, timer->it.cpu.expires, |
849 | &itp->it_value); |
850 | return; |
851 | } |
852 | |
853 | /* |
854 | * Sample the clock to take the difference with the expiry time. |
855 | */ |
856 | if (CPUCLOCK_PERTHREAD(timer->it_clock)) { |
857 | cpu_clock_sample(timer->it_clock, p, &now); |
858 | clear_dead = p->exit_state; |
859 | } else { |
860 | read_lock(&tasklist_lock); |
861 | if (unlikely(p->sighand == NULL)) { |
862 | /* |
863 | * The process has been reaped. |
864 | * We can't even collect a sample any more. |
865 | * Call the timer disarmed, nothing else to do. |
866 | */ |
867 | put_task_struct(p); |
868 | timer->it.cpu.task = NULL; |
869 | timer->it.cpu.expires.sched = 0; |
870 | read_unlock(&tasklist_lock); |
871 | goto dead; |
872 | } else { |
873 | cpu_timer_sample_group(timer->it_clock, p, &now); |
874 | clear_dead = (unlikely(p->exit_state) && |
875 | thread_group_empty(p)); |
876 | } |
877 | read_unlock(&tasklist_lock); |
878 | } |
879 | |
880 | if (unlikely(clear_dead)) { |
881 | /* |
882 | * We've noticed that the thread is dead, but |
883 | * not yet reaped. Take this opportunity to |
884 | * drop our task ref. |
885 | */ |
886 | clear_dead_task(timer, now); |
887 | goto dead; |
888 | } |
889 | |
890 | if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) { |
891 | sample_to_timespec(timer->it_clock, |
892 | cpu_time_sub(timer->it_clock, |
893 | timer->it.cpu.expires, now), |
894 | &itp->it_value); |
895 | } else { |
896 | /* |
897 | * The timer should have expired already, but the firing |
898 | * hasn't taken place yet. Say it's just about to expire. |
899 | */ |
900 | itp->it_value.tv_nsec = 1; |
901 | itp->it_value.tv_sec = 0; |
902 | } |
903 | } |
904 | |
905 | /* |
906 | * Check for any per-thread CPU timers that have fired and move them off |
907 | * the tsk->cpu_timers[N] list onto the firing list. Here we update the |
908 | * tsk->it_*_expires values to reflect the remaining thread CPU timers. |
909 | */ |
910 | static void check_thread_timers(struct task_struct *tsk, |
911 | struct list_head *firing) |
912 | { |
913 | int maxfire; |
914 | struct list_head *timers = tsk->cpu_timers; |
915 | struct signal_struct *const sig = tsk->signal; |
916 | unsigned long soft; |
917 | |
918 | maxfire = 20; |
919 | tsk->cputime_expires.prof_exp = cputime_zero; |
920 | while (!list_empty(timers)) { |
921 | struct cpu_timer_list *t = list_first_entry(timers, |
922 | struct cpu_timer_list, |
923 | entry); |
924 | if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) { |
925 | tsk->cputime_expires.prof_exp = t->expires.cpu; |
926 | break; |
927 | } |
928 | t->firing = 1; |
929 | list_move_tail(&t->entry, firing); |
930 | } |
931 | |
932 | ++timers; |
933 | maxfire = 20; |
934 | tsk->cputime_expires.virt_exp = cputime_zero; |
935 | while (!list_empty(timers)) { |
936 | struct cpu_timer_list *t = list_first_entry(timers, |
937 | struct cpu_timer_list, |
938 | entry); |
939 | if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) { |
940 | tsk->cputime_expires.virt_exp = t->expires.cpu; |
941 | break; |
942 | } |
943 | t->firing = 1; |
944 | list_move_tail(&t->entry, firing); |
945 | } |
946 | |
947 | ++timers; |
948 | maxfire = 20; |
949 | tsk->cputime_expires.sched_exp = 0; |
950 | while (!list_empty(timers)) { |
951 | struct cpu_timer_list *t = list_first_entry(timers, |
952 | struct cpu_timer_list, |
953 | entry); |
954 | if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) { |
955 | tsk->cputime_expires.sched_exp = t->expires.sched; |
956 | break; |
957 | } |
958 | t->firing = 1; |
959 | list_move_tail(&t->entry, firing); |
960 | } |
961 | |
962 | /* |
963 | * Check for the special case thread timers. |
964 | */ |
965 | soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur); |
966 | if (soft != RLIM_INFINITY) { |
967 | unsigned long hard = |
968 | ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max); |
969 | |
970 | if (hard != RLIM_INFINITY && |
971 | tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) { |
972 | /* |
973 | * At the hard limit, we just die. |
974 | * No need to calculate anything else now. |
975 | */ |
976 | __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk); |
977 | return; |
978 | } |
979 | if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) { |
980 | /* |
981 | * At the soft limit, send a SIGXCPU every second. |
982 | */ |
983 | if (soft < hard) { |
984 | soft += USEC_PER_SEC; |
985 | sig->rlim[RLIMIT_RTTIME].rlim_cur = soft; |
986 | } |
987 | printk(KERN_INFO |
988 | "RT Watchdog Timeout: %s[%d]\n", |
989 | tsk->comm, task_pid_nr(tsk)); |
990 | __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk); |
991 | } |
992 | } |
993 | } |
994 | |
995 | static void stop_process_timers(struct signal_struct *sig) |
996 | { |
997 | struct thread_group_cputimer *cputimer = &sig->cputimer; |
998 | unsigned long flags; |
999 | |
1000 | spin_lock_irqsave(&cputimer->lock, flags); |
1001 | cputimer->running = 0; |
1002 | spin_unlock_irqrestore(&cputimer->lock, flags); |
1003 | } |
1004 | |
1005 | static u32 onecputick; |
1006 | |
1007 | static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it, |
1008 | cputime_t *expires, cputime_t cur_time, int signo) |
1009 | { |
1010 | if (cputime_eq(it->expires, cputime_zero)) |
1011 | return; |
1012 | |
1013 | if (cputime_ge(cur_time, it->expires)) { |
1014 | if (!cputime_eq(it->incr, cputime_zero)) { |
1015 | it->expires = cputime_add(it->expires, it->incr); |
1016 | it->error += it->incr_error; |
1017 | if (it->error >= onecputick) { |
1018 | it->expires = cputime_sub(it->expires, |
1019 | cputime_one_jiffy); |
1020 | it->error -= onecputick; |
1021 | } |
1022 | } else { |
1023 | it->expires = cputime_zero; |
1024 | } |
1025 | |
1026 | trace_itimer_expire(signo == SIGPROF ? |
1027 | ITIMER_PROF : ITIMER_VIRTUAL, |
1028 | tsk->signal->leader_pid, cur_time); |
1029 | __group_send_sig_info(signo, SEND_SIG_PRIV, tsk); |
1030 | } |
1031 | |
1032 | if (!cputime_eq(it->expires, cputime_zero) && |
1033 | (cputime_eq(*expires, cputime_zero) || |
1034 | cputime_lt(it->expires, *expires))) { |
1035 | *expires = it->expires; |
1036 | } |
1037 | } |
1038 | |
1039 | /** |
1040 | * task_cputime_zero - Check a task_cputime struct for all zero fields. |
1041 | * |
1042 | * @cputime: The struct to compare. |
1043 | * |
1044 | * Checks @cputime to see if all fields are zero. Returns true if all fields |
1045 | * are zero, false if any field is nonzero. |
1046 | */ |
1047 | static inline int task_cputime_zero(const struct task_cputime *cputime) |
1048 | { |
1049 | if (cputime_eq(cputime->utime, cputime_zero) && |
1050 | cputime_eq(cputime->stime, cputime_zero) && |
1051 | cputime->sum_exec_runtime == 0) |
1052 | return 1; |
1053 | return 0; |
1054 | } |
1055 | |
1056 | /* |
1057 | * Check for any per-thread CPU timers that have fired and move them |
1058 | * off the tsk->*_timers list onto the firing list. Per-thread timers |
1059 | * have already been taken off. |
1060 | */ |
1061 | static void check_process_timers(struct task_struct *tsk, |
1062 | struct list_head *firing) |
1063 | { |
1064 | int maxfire; |
1065 | struct signal_struct *const sig = tsk->signal; |
1066 | cputime_t utime, ptime, virt_expires, prof_expires; |
1067 | unsigned long long sum_sched_runtime, sched_expires; |
1068 | struct list_head *timers = sig->cpu_timers; |
1069 | struct task_cputime cputime; |
1070 | unsigned long soft; |
1071 | |
1072 | /* |
1073 | * Collect the current process totals. |
1074 | */ |
1075 | thread_group_cputimer(tsk, &cputime); |
1076 | utime = cputime.utime; |
1077 | ptime = cputime_add(utime, cputime.stime); |
1078 | sum_sched_runtime = cputime.sum_exec_runtime; |
1079 | maxfire = 20; |
1080 | prof_expires = cputime_zero; |
1081 | while (!list_empty(timers)) { |
1082 | struct cpu_timer_list *tl = list_first_entry(timers, |
1083 | struct cpu_timer_list, |
1084 | entry); |
1085 | if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) { |
1086 | prof_expires = tl->expires.cpu; |
1087 | break; |
1088 | } |
1089 | tl->firing = 1; |
1090 | list_move_tail(&tl->entry, firing); |
1091 | } |
1092 | |
1093 | ++timers; |
1094 | maxfire = 20; |
1095 | virt_expires = cputime_zero; |
1096 | while (!list_empty(timers)) { |
1097 | struct cpu_timer_list *tl = list_first_entry(timers, |
1098 | struct cpu_timer_list, |
1099 | entry); |
1100 | if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) { |
1101 | virt_expires = tl->expires.cpu; |
1102 | break; |
1103 | } |
1104 | tl->firing = 1; |
1105 | list_move_tail(&tl->entry, firing); |
1106 | } |
1107 | |
1108 | ++timers; |
1109 | maxfire = 20; |
1110 | sched_expires = 0; |
1111 | while (!list_empty(timers)) { |
1112 | struct cpu_timer_list *tl = list_first_entry(timers, |
1113 | struct cpu_timer_list, |
1114 | entry); |
1115 | if (!--maxfire || sum_sched_runtime < tl->expires.sched) { |
1116 | sched_expires = tl->expires.sched; |
1117 | break; |
1118 | } |
1119 | tl->firing = 1; |
1120 | list_move_tail(&tl->entry, firing); |
1121 | } |
1122 | |
1123 | /* |
1124 | * Check for the special case process timers. |
1125 | */ |
1126 | check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime, |
1127 | SIGPROF); |
1128 | check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime, |
1129 | SIGVTALRM); |
1130 | soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); |
1131 | if (soft != RLIM_INFINITY) { |
1132 | unsigned long psecs = cputime_to_secs(ptime); |
1133 | unsigned long hard = |
1134 | ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max); |
1135 | cputime_t x; |
1136 | if (psecs >= hard) { |
1137 | /* |
1138 | * At the hard limit, we just die. |
1139 | * No need to calculate anything else now. |
1140 | */ |
1141 | __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk); |
1142 | return; |
1143 | } |
1144 | if (psecs >= soft) { |
1145 | /* |
1146 | * At the soft limit, send a SIGXCPU every second. |
1147 | */ |
1148 | __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk); |
1149 | if (soft < hard) { |
1150 | soft++; |
1151 | sig->rlim[RLIMIT_CPU].rlim_cur = soft; |
1152 | } |
1153 | } |
1154 | x = secs_to_cputime(soft); |
1155 | if (cputime_eq(prof_expires, cputime_zero) || |
1156 | cputime_lt(x, prof_expires)) { |
1157 | prof_expires = x; |
1158 | } |
1159 | } |
1160 | |
1161 | sig->cputime_expires.prof_exp = prof_expires; |
1162 | sig->cputime_expires.virt_exp = virt_expires; |
1163 | sig->cputime_expires.sched_exp = sched_expires; |
1164 | if (task_cputime_zero(&sig->cputime_expires)) |
1165 | stop_process_timers(sig); |
1166 | } |
1167 | |
1168 | /* |
1169 | * This is called from the signal code (via do_schedule_next_timer) |
1170 | * when the last timer signal was delivered and we have to reload the timer. |
1171 | */ |
1172 | void posix_cpu_timer_schedule(struct k_itimer *timer) |
1173 | { |
1174 | struct task_struct *p = timer->it.cpu.task; |
1175 | union cpu_time_count now; |
1176 | |
1177 | if (unlikely(p == NULL)) |
1178 | /* |
1179 | * The task was cleaned up already, no future firings. |
1180 | */ |
1181 | goto out; |
1182 | |
1183 | /* |
1184 | * Fetch the current sample and update the timer's expiry time. |
1185 | */ |
1186 | if (CPUCLOCK_PERTHREAD(timer->it_clock)) { |
1187 | cpu_clock_sample(timer->it_clock, p, &now); |
1188 | bump_cpu_timer(timer, now); |
1189 | if (unlikely(p->exit_state)) { |
1190 | clear_dead_task(timer, now); |
1191 | goto out; |
1192 | } |
1193 | read_lock(&tasklist_lock); /* arm_timer needs it. */ |
1194 | spin_lock(&p->sighand->siglock); |
1195 | } else { |
1196 | read_lock(&tasklist_lock); |
1197 | if (unlikely(p->sighand == NULL)) { |
1198 | /* |
1199 | * The process has been reaped. |
1200 | * We can't even collect a sample any more. |
1201 | */ |
1202 | put_task_struct(p); |
1203 | timer->it.cpu.task = p = NULL; |
1204 | timer->it.cpu.expires.sched = 0; |
1205 | goto out_unlock; |
1206 | } else if (unlikely(p->exit_state) && thread_group_empty(p)) { |
1207 | /* |
1208 | * We've noticed that the thread is dead, but |
1209 | * not yet reaped. Take this opportunity to |
1210 | * drop our task ref. |
1211 | */ |
1212 | clear_dead_task(timer, now); |
1213 | goto out_unlock; |
1214 | } |
1215 | spin_lock(&p->sighand->siglock); |
1216 | cpu_timer_sample_group(timer->it_clock, p, &now); |
1217 | bump_cpu_timer(timer, now); |
1218 | /* Leave the tasklist_lock locked for the call below. */ |
1219 | } |
1220 | |
1221 | /* |
1222 | * Now re-arm for the new expiry time. |
1223 | */ |
1224 | BUG_ON(!irqs_disabled()); |
1225 | arm_timer(timer); |
1226 | spin_unlock(&p->sighand->siglock); |
1227 | |
1228 | out_unlock: |
1229 | read_unlock(&tasklist_lock); |
1230 | |
1231 | out: |
1232 | timer->it_overrun_last = timer->it_overrun; |
1233 | timer->it_overrun = -1; |
1234 | ++timer->it_requeue_pending; |
1235 | } |
1236 | |
1237 | /** |
1238 | * task_cputime_expired - Compare two task_cputime entities. |
1239 | * |
1240 | * @sample: The task_cputime structure to be checked for expiration. |
1241 | * @expires: Expiration times, against which @sample will be checked. |
1242 | * |
1243 | * Checks @sample against @expires to see if any field of @sample has expired. |
1244 | * Returns true if any field of the former is greater than the corresponding |
1245 | * field of the latter if the latter field is set. Otherwise returns false. |
1246 | */ |
1247 | static inline int task_cputime_expired(const struct task_cputime *sample, |
1248 | const struct task_cputime *expires) |
1249 | { |
1250 | if (!cputime_eq(expires->utime, cputime_zero) && |
1251 | cputime_ge(sample->utime, expires->utime)) |
1252 | return 1; |
1253 | if (!cputime_eq(expires->stime, cputime_zero) && |
1254 | cputime_ge(cputime_add(sample->utime, sample->stime), |
1255 | expires->stime)) |
1256 | return 1; |
1257 | if (expires->sum_exec_runtime != 0 && |
1258 | sample->sum_exec_runtime >= expires->sum_exec_runtime) |
1259 | return 1; |
1260 | return 0; |
1261 | } |
1262 | |
1263 | /** |
1264 | * fastpath_timer_check - POSIX CPU timers fast path. |
1265 | * |
1266 | * @tsk: The task (thread) being checked. |
1267 | * |
1268 | * Check the task and thread group timers. If both are zero (there are no |
1269 | * timers set) return false. Otherwise snapshot the task and thread group |
1270 | * timers and compare them with the corresponding expiration times. Return |
1271 | * true if a timer has expired, else return false. |
1272 | */ |
1273 | static inline int fastpath_timer_check(struct task_struct *tsk) |
1274 | { |
1275 | struct signal_struct *sig; |
1276 | |
1277 | if (!task_cputime_zero(&tsk->cputime_expires)) { |
1278 | struct task_cputime task_sample = { |
1279 | .utime = tsk->utime, |
1280 | .stime = tsk->stime, |
1281 | .sum_exec_runtime = tsk->se.sum_exec_runtime |
1282 | }; |
1283 | |
1284 | if (task_cputime_expired(&task_sample, &tsk->cputime_expires)) |
1285 | return 1; |
1286 | } |
1287 | |
1288 | sig = tsk->signal; |
1289 | if (sig->cputimer.running) { |
1290 | struct task_cputime group_sample; |
1291 | |
1292 | spin_lock(&sig->cputimer.lock); |
1293 | group_sample = sig->cputimer.cputime; |
1294 | spin_unlock(&sig->cputimer.lock); |
1295 | |
1296 | if (task_cputime_expired(&group_sample, &sig->cputime_expires)) |
1297 | return 1; |
1298 | } |
1299 | |
1300 | return 0; |
1301 | } |
1302 | |
1303 | /* |
1304 | * This is called from the timer interrupt handler. The irq handler has |
1305 | * already updated our counts. We need to check if any timers fire now. |
1306 | * Interrupts are disabled. |
1307 | */ |
1308 | void run_posix_cpu_timers(struct task_struct *tsk) |
1309 | { |
1310 | LIST_HEAD(firing); |
1311 | struct k_itimer *timer, *next; |
1312 | unsigned long flags; |
1313 | |
1314 | BUG_ON(!irqs_disabled()); |
1315 | |
1316 | /* |
1317 | * The fast path checks that there are no expired thread or thread |
1318 | * group timers. If that's so, just return. |
1319 | */ |
1320 | if (!fastpath_timer_check(tsk)) |
1321 | return; |
1322 | |
1323 | if (!lock_task_sighand(tsk, &flags)) |
1324 | return; |
1325 | /* |
1326 | * Here we take off tsk->signal->cpu_timers[N] and |
1327 | * tsk->cpu_timers[N] all the timers that are firing, and |
1328 | * put them on the firing list. |
1329 | */ |
1330 | check_thread_timers(tsk, &firing); |
1331 | /* |
1332 | * If there are any active process wide timers (POSIX 1.b, itimers, |
1333 | * RLIMIT_CPU) cputimer must be running. |
1334 | */ |
1335 | if (tsk->signal->cputimer.running) |
1336 | check_process_timers(tsk, &firing); |
1337 | |
1338 | /* |
1339 | * We must release these locks before taking any timer's lock. |
1340 | * There is a potential race with timer deletion here, as the |
1341 | * siglock now protects our private firing list. We have set |
1342 | * the firing flag in each timer, so that a deletion attempt |
1343 | * that gets the timer lock before we do will give it up and |
1344 | * spin until we've taken care of that timer below. |
1345 | */ |
1346 | unlock_task_sighand(tsk, &flags); |
1347 | |
1348 | /* |
1349 | * Now that all the timers on our list have the firing flag, |
1350 | * no one will touch their list entries but us. We'll take |
1351 | * each timer's lock before clearing its firing flag, so no |
1352 | * timer call will interfere. |
1353 | */ |
1354 | list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) { |
1355 | int cpu_firing; |
1356 | |
1357 | spin_lock(&timer->it_lock); |
1358 | list_del_init(&timer->it.cpu.entry); |
1359 | cpu_firing = timer->it.cpu.firing; |
1360 | timer->it.cpu.firing = 0; |
1361 | /* |
1362 | * The firing flag is -1 if we collided with a reset |
1363 | * of the timer, which already reported this |
1364 | * almost-firing as an overrun. So don't generate an event. |
1365 | */ |
1366 | if (likely(cpu_firing >= 0)) |
1367 | cpu_timer_fire(timer); |
1368 | spin_unlock(&timer->it_lock); |
1369 | } |
1370 | } |
1371 | |
1372 | /* |
1373 | * Set one of the process-wide special case CPU timers or RLIMIT_CPU. |
1374 | * The tsk->sighand->siglock must be held by the caller. |
1375 | */ |
1376 | void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, |
1377 | cputime_t *newval, cputime_t *oldval) |
1378 | { |
1379 | union cpu_time_count now; |
1380 | |
1381 | BUG_ON(clock_idx == CPUCLOCK_SCHED); |
1382 | cpu_timer_sample_group(clock_idx, tsk, &now); |
1383 | |
1384 | if (oldval) { |
1385 | /* |
1386 | * We are setting itimer. The *oldval is absolute and we update |
1387 | * it to be relative, *newval argument is relative and we update |
1388 | * it to be absolute. |
1389 | */ |
1390 | if (!cputime_eq(*oldval, cputime_zero)) { |
1391 | if (cputime_le(*oldval, now.cpu)) { |
1392 | /* Just about to fire. */ |
1393 | *oldval = cputime_one_jiffy; |
1394 | } else { |
1395 | *oldval = cputime_sub(*oldval, now.cpu); |
1396 | } |
1397 | } |
1398 | |
1399 | if (cputime_eq(*newval, cputime_zero)) |
1400 | return; |
1401 | *newval = cputime_add(*newval, now.cpu); |
1402 | } |
1403 | |
1404 | /* |
1405 | * Update expiration cache if we are the earliest timer, or eventually |
1406 | * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire. |
1407 | */ |
1408 | switch (clock_idx) { |
1409 | case CPUCLOCK_PROF: |
1410 | if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval)) |
1411 | tsk->signal->cputime_expires.prof_exp = *newval; |
1412 | break; |
1413 | case CPUCLOCK_VIRT: |
1414 | if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval)) |
1415 | tsk->signal->cputime_expires.virt_exp = *newval; |
1416 | break; |
1417 | } |
1418 | } |
1419 | |
1420 | static int do_cpu_nanosleep(const clockid_t which_clock, int flags, |
1421 | struct timespec *rqtp, struct itimerspec *it) |
1422 | { |
1423 | struct k_itimer timer; |
1424 | int error; |
1425 | |
1426 | /* |
1427 | * Set up a temporary timer and then wait for it to go off. |
1428 | */ |
1429 | memset(&timer, 0, sizeof timer); |
1430 | spin_lock_init(&timer.it_lock); |
1431 | timer.it_clock = which_clock; |
1432 | timer.it_overrun = -1; |
1433 | error = posix_cpu_timer_create(&timer); |
1434 | timer.it_process = current; |
1435 | if (!error) { |
1436 | static struct itimerspec zero_it; |
1437 | |
1438 | memset(it, 0, sizeof *it); |
1439 | it->it_value = *rqtp; |
1440 | |
1441 | spin_lock_irq(&timer.it_lock); |
1442 | error = posix_cpu_timer_set(&timer, flags, it, NULL); |
1443 | if (error) { |
1444 | spin_unlock_irq(&timer.it_lock); |
1445 | return error; |
1446 | } |
1447 | |
1448 | while (!signal_pending(current)) { |
1449 | if (timer.it.cpu.expires.sched == 0) { |
1450 | /* |
1451 | * Our timer fired and was reset. |
1452 | */ |
1453 | spin_unlock_irq(&timer.it_lock); |
1454 | return 0; |
1455 | } |
1456 | |
1457 | /* |
1458 | * Block until cpu_timer_fire (or a signal) wakes us. |
1459 | */ |
1460 | __set_current_state(TASK_INTERRUPTIBLE); |
1461 | spin_unlock_irq(&timer.it_lock); |
1462 | schedule(); |
1463 | spin_lock_irq(&timer.it_lock); |
1464 | } |
1465 | |
1466 | /* |
1467 | * We were interrupted by a signal. |
1468 | */ |
1469 | sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp); |
1470 | posix_cpu_timer_set(&timer, 0, &zero_it, it); |
1471 | spin_unlock_irq(&timer.it_lock); |
1472 | |
1473 | if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) { |
1474 | /* |
1475 | * It actually did fire already. |
1476 | */ |
1477 | return 0; |
1478 | } |
1479 | |
1480 | error = -ERESTART_RESTARTBLOCK; |
1481 | } |
1482 | |
1483 | return error; |
1484 | } |
1485 | |
1486 | static long posix_cpu_nsleep_restart(struct restart_block *restart_block); |
1487 | |
1488 | static int posix_cpu_nsleep(const clockid_t which_clock, int flags, |
1489 | struct timespec *rqtp, struct timespec __user *rmtp) |
1490 | { |
1491 | struct restart_block *restart_block = |
1492 | ¤t_thread_info()->restart_block; |
1493 | struct itimerspec it; |
1494 | int error; |
1495 | |
1496 | /* |
1497 | * Diagnose required errors first. |
1498 | */ |
1499 | if (CPUCLOCK_PERTHREAD(which_clock) && |
1500 | (CPUCLOCK_PID(which_clock) == 0 || |
1501 | CPUCLOCK_PID(which_clock) == current->pid)) |
1502 | return -EINVAL; |
1503 | |
1504 | error = do_cpu_nanosleep(which_clock, flags, rqtp, &it); |
1505 | |
1506 | if (error == -ERESTART_RESTARTBLOCK) { |
1507 | |
1508 | if (flags & TIMER_ABSTIME) |
1509 | return -ERESTARTNOHAND; |
1510 | /* |
1511 | * Report back to the user the time still remaining. |
1512 | */ |
1513 | if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp)) |
1514 | return -EFAULT; |
1515 | |
1516 | restart_block->fn = posix_cpu_nsleep_restart; |
1517 | restart_block->nanosleep.index = which_clock; |
1518 | restart_block->nanosleep.rmtp = rmtp; |
1519 | restart_block->nanosleep.expires = timespec_to_ns(rqtp); |
1520 | } |
1521 | return error; |
1522 | } |
1523 | |
1524 | static long posix_cpu_nsleep_restart(struct restart_block *restart_block) |
1525 | { |
1526 | clockid_t which_clock = restart_block->nanosleep.index; |
1527 | struct timespec t; |
1528 | struct itimerspec it; |
1529 | int error; |
1530 | |
1531 | t = ns_to_timespec(restart_block->nanosleep.expires); |
1532 | |
1533 | error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it); |
1534 | |
1535 | if (error == -ERESTART_RESTARTBLOCK) { |
1536 | struct timespec __user *rmtp = restart_block->nanosleep.rmtp; |
1537 | /* |
1538 | * Report back to the user the time still remaining. |
1539 | */ |
1540 | if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp)) |
1541 | return -EFAULT; |
1542 | |
1543 | restart_block->nanosleep.expires = timespec_to_ns(&t); |
1544 | } |
1545 | return error; |
1546 | |
1547 | } |
1548 | |
1549 | #define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED) |
1550 | #define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED) |
1551 | |
1552 | static int process_cpu_clock_getres(const clockid_t which_clock, |
1553 | struct timespec *tp) |
1554 | { |
1555 | return posix_cpu_clock_getres(PROCESS_CLOCK, tp); |
1556 | } |
1557 | static int process_cpu_clock_get(const clockid_t which_clock, |
1558 | struct timespec *tp) |
1559 | { |
1560 | return posix_cpu_clock_get(PROCESS_CLOCK, tp); |
1561 | } |
1562 | static int process_cpu_timer_create(struct k_itimer *timer) |
1563 | { |
1564 | timer->it_clock = PROCESS_CLOCK; |
1565 | return posix_cpu_timer_create(timer); |
1566 | } |
1567 | static int process_cpu_nsleep(const clockid_t which_clock, int flags, |
1568 | struct timespec *rqtp, |
1569 | struct timespec __user *rmtp) |
1570 | { |
1571 | return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp); |
1572 | } |
1573 | static long process_cpu_nsleep_restart(struct restart_block *restart_block) |
1574 | { |
1575 | return -EINVAL; |
1576 | } |
1577 | static int thread_cpu_clock_getres(const clockid_t which_clock, |
1578 | struct timespec *tp) |
1579 | { |
1580 | return posix_cpu_clock_getres(THREAD_CLOCK, tp); |
1581 | } |
1582 | static int thread_cpu_clock_get(const clockid_t which_clock, |
1583 | struct timespec *tp) |
1584 | { |
1585 | return posix_cpu_clock_get(THREAD_CLOCK, tp); |
1586 | } |
1587 | static int thread_cpu_timer_create(struct k_itimer *timer) |
1588 | { |
1589 | timer->it_clock = THREAD_CLOCK; |
1590 | return posix_cpu_timer_create(timer); |
1591 | } |
1592 | |
1593 | struct k_clock clock_posix_cpu = { |
1594 | .clock_getres = posix_cpu_clock_getres, |
1595 | .clock_set = posix_cpu_clock_set, |
1596 | .clock_get = posix_cpu_clock_get, |
1597 | .timer_create = posix_cpu_timer_create, |
1598 | .nsleep = posix_cpu_nsleep, |
1599 | .nsleep_restart = posix_cpu_nsleep_restart, |
1600 | .timer_set = posix_cpu_timer_set, |
1601 | .timer_del = posix_cpu_timer_del, |
1602 | .timer_get = posix_cpu_timer_get, |
1603 | }; |
1604 | |
1605 | static __init int init_posix_cpu_timers(void) |
1606 | { |
1607 | struct k_clock process = { |
1608 | .clock_getres = process_cpu_clock_getres, |
1609 | .clock_get = process_cpu_clock_get, |
1610 | .timer_create = process_cpu_timer_create, |
1611 | .nsleep = process_cpu_nsleep, |
1612 | .nsleep_restart = process_cpu_nsleep_restart, |
1613 | }; |
1614 | struct k_clock thread = { |
1615 | .clock_getres = thread_cpu_clock_getres, |
1616 | .clock_get = thread_cpu_clock_get, |
1617 | .timer_create = thread_cpu_timer_create, |
1618 | }; |
1619 | struct timespec ts; |
1620 | |
1621 | posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process); |
1622 | posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread); |
1623 | |
1624 | cputime_to_timespec(cputime_one_jiffy, &ts); |
1625 | onecputick = ts.tv_nsec; |
1626 | WARN_ON(ts.tv_sec != 0); |
1627 | |
1628 | return 0; |
1629 | } |
1630 | __initcall(init_posix_cpu_timers); |
1631 |
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