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1 | /* |
2 | * linux/kernel/posix-timers.c |
3 | * |
4 | * |
5 | * 2002-10-15 Posix Clocks & timers |
6 | * by George Anzinger george@mvista.com |
7 | * |
8 | * Copyright (C) 2002 2003 by MontaVista Software. |
9 | * |
10 | * 2004-06-01 Fix CLOCK_REALTIME clock/timer TIMER_ABSTIME bug. |
11 | * Copyright (C) 2004 Boris Hu |
12 | * |
13 | * This program is free software; you can redistribute it and/or modify |
14 | * it under the terms of the GNU General Public License as published by |
15 | * the Free Software Foundation; either version 2 of the License, or (at |
16 | * your option) any later version. |
17 | * |
18 | * This program is distributed in the hope that it will be useful, but |
19 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
20 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
21 | * General Public License for more details. |
22 | |
23 | * You should have received a copy of the GNU General Public License |
24 | * along with this program; if not, write to the Free Software |
25 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
26 | * |
27 | * MontaVista Software | 1237 East Arques Avenue | Sunnyvale | CA 94085 | USA |
28 | */ |
29 | |
30 | /* These are all the functions necessary to implement |
31 | * POSIX clocks & timers |
32 | */ |
33 | #include <linux/mm.h> |
34 | #include <linux/interrupt.h> |
35 | #include <linux/slab.h> |
36 | #include <linux/time.h> |
37 | #include <linux/mutex.h> |
38 | |
39 | #include <asm/uaccess.h> |
40 | #include <linux/list.h> |
41 | #include <linux/init.h> |
42 | #include <linux/compiler.h> |
43 | #include <linux/idr.h> |
44 | #include <linux/posix-timers.h> |
45 | #include <linux/syscalls.h> |
46 | #include <linux/wait.h> |
47 | #include <linux/workqueue.h> |
48 | #include <linux/module.h> |
49 | |
50 | /* |
51 | * Management arrays for POSIX timers. Timers are kept in slab memory |
52 | * Timer ids are allocated by an external routine that keeps track of the |
53 | * id and the timer. The external interface is: |
54 | * |
55 | * void *idr_find(struct idr *idp, int id); to find timer_id <id> |
56 | * int idr_get_new(struct idr *idp, void *ptr); to get a new id and |
57 | * related it to <ptr> |
58 | * void idr_remove(struct idr *idp, int id); to release <id> |
59 | * void idr_init(struct idr *idp); to initialize <idp> |
60 | * which we supply. |
61 | * The idr_get_new *may* call slab for more memory so it must not be |
62 | * called under a spin lock. Likewise idr_remore may release memory |
63 | * (but it may be ok to do this under a lock...). |
64 | * idr_find is just a memory look up and is quite fast. A -1 return |
65 | * indicates that the requested id does not exist. |
66 | */ |
67 | |
68 | /* |
69 | * Lets keep our timers in a slab cache :-) |
70 | */ |
71 | static struct kmem_cache *posix_timers_cache; |
72 | static struct idr posix_timers_id; |
73 | static DEFINE_SPINLOCK(idr_lock); |
74 | |
75 | /* |
76 | * we assume that the new SIGEV_THREAD_ID shares no bits with the other |
77 | * SIGEV values. Here we put out an error if this assumption fails. |
78 | */ |
79 | #if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \ |
80 | ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD)) |
81 | #error "SIGEV_THREAD_ID must not share bit with other SIGEV values!" |
82 | #endif |
83 | |
84 | |
85 | /* |
86 | * The timer ID is turned into a timer address by idr_find(). |
87 | * Verifying a valid ID consists of: |
88 | * |
89 | * a) checking that idr_find() returns other than -1. |
90 | * b) checking that the timer id matches the one in the timer itself. |
91 | * c) that the timer owner is in the callers thread group. |
92 | */ |
93 | |
94 | /* |
95 | * CLOCKs: The POSIX standard calls for a couple of clocks and allows us |
96 | * to implement others. This structure defines the various |
97 | * clocks and allows the possibility of adding others. We |
98 | * provide an interface to add clocks to the table and expect |
99 | * the "arch" code to add at least one clock that is high |
100 | * resolution. Here we define the standard CLOCK_REALTIME as a |
101 | * 1/HZ resolution clock. |
102 | * |
103 | * RESOLUTION: Clock resolution is used to round up timer and interval |
104 | * times, NOT to report clock times, which are reported with as |
105 | * much resolution as the system can muster. In some cases this |
106 | * resolution may depend on the underlying clock hardware and |
107 | * may not be quantifiable until run time, and only then is the |
108 | * necessary code is written. The standard says we should say |
109 | * something about this issue in the documentation... |
110 | * |
111 | * FUNCTIONS: The CLOCKs structure defines possible functions to handle |
112 | * various clock functions. For clocks that use the standard |
113 | * system timer code these entries should be NULL. This will |
114 | * allow dispatch without the overhead of indirect function |
115 | * calls. CLOCKS that depend on other sources (e.g. WWV or GPS) |
116 | * must supply functions here, even if the function just returns |
117 | * ENOSYS. The standard POSIX timer management code assumes the |
118 | * following: 1.) The k_itimer struct (sched.h) is used for the |
119 | * timer. 2.) The list, it_lock, it_clock, it_id and it_pid |
120 | * fields are not modified by timer code. |
121 | * |
122 | * At this time all functions EXCEPT clock_nanosleep can be |
123 | * redirected by the CLOCKS structure. Clock_nanosleep is in |
124 | * there, but the code ignores it. |
125 | * |
126 | * Permissions: It is assumed that the clock_settime() function defined |
127 | * for each clock will take care of permission checks. Some |
128 | * clocks may be set able by any user (i.e. local process |
129 | * clocks) others not. Currently the only set able clock we |
130 | * have is CLOCK_REALTIME and its high res counter part, both of |
131 | * which we beg off on and pass to do_sys_settimeofday(). |
132 | */ |
133 | |
134 | static struct k_clock posix_clocks[MAX_CLOCKS]; |
135 | |
136 | /* |
137 | * These ones are defined below. |
138 | */ |
139 | static int common_nsleep(const clockid_t, int flags, struct timespec *t, |
140 | struct timespec __user *rmtp); |
141 | static void common_timer_get(struct k_itimer *, struct itimerspec *); |
142 | static int common_timer_set(struct k_itimer *, int, |
143 | struct itimerspec *, struct itimerspec *); |
144 | static int common_timer_del(struct k_itimer *timer); |
145 | |
146 | static enum hrtimer_restart posix_timer_fn(struct hrtimer *data); |
147 | |
148 | static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags); |
149 | |
150 | static inline void unlock_timer(struct k_itimer *timr, unsigned long flags) |
151 | { |
152 | spin_unlock_irqrestore(&timr->it_lock, flags); |
153 | } |
154 | |
155 | /* |
156 | * Call the k_clock hook function if non-null, or the default function. |
157 | */ |
158 | #define CLOCK_DISPATCH(clock, call, arglist) \ |
159 | ((clock) < 0 ? posix_cpu_##call arglist : \ |
160 | (posix_clocks[clock].call != NULL \ |
161 | ? (*posix_clocks[clock].call) arglist : common_##call arglist)) |
162 | |
163 | /* |
164 | * Default clock hook functions when the struct k_clock passed |
165 | * to register_posix_clock leaves a function pointer null. |
166 | * |
167 | * The function common_CALL is the default implementation for |
168 | * the function pointer CALL in struct k_clock. |
169 | */ |
170 | |
171 | static inline int common_clock_getres(const clockid_t which_clock, |
172 | struct timespec *tp) |
173 | { |
174 | tp->tv_sec = 0; |
175 | tp->tv_nsec = posix_clocks[which_clock].res; |
176 | return 0; |
177 | } |
178 | |
179 | /* |
180 | * Get real time for posix timers |
181 | */ |
182 | static int common_clock_get(clockid_t which_clock, struct timespec *tp) |
183 | { |
184 | ktime_get_real_ts(tp); |
185 | return 0; |
186 | } |
187 | |
188 | static inline int common_clock_set(const clockid_t which_clock, |
189 | struct timespec *tp) |
190 | { |
191 | return do_sys_settimeofday(tp, NULL); |
192 | } |
193 | |
194 | static int common_timer_create(struct k_itimer *new_timer) |
195 | { |
196 | hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0); |
197 | return 0; |
198 | } |
199 | |
200 | static int no_timer_create(struct k_itimer *new_timer) |
201 | { |
202 | return -EOPNOTSUPP; |
203 | } |
204 | |
205 | static int no_nsleep(const clockid_t which_clock, int flags, |
206 | struct timespec *tsave, struct timespec __user *rmtp) |
207 | { |
208 | return -EOPNOTSUPP; |
209 | } |
210 | |
211 | /* |
212 | * Return nonzero if we know a priori this clockid_t value is bogus. |
213 | */ |
214 | static inline int invalid_clockid(const clockid_t which_clock) |
215 | { |
216 | if (which_clock < 0) /* CPU clock, posix_cpu_* will check it */ |
217 | return 0; |
218 | if ((unsigned) which_clock >= MAX_CLOCKS) |
219 | return 1; |
220 | if (posix_clocks[which_clock].clock_getres != NULL) |
221 | return 0; |
222 | if (posix_clocks[which_clock].res != 0) |
223 | return 0; |
224 | return 1; |
225 | } |
226 | |
227 | /* |
228 | * Get monotonic time for posix timers |
229 | */ |
230 | static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp) |
231 | { |
232 | ktime_get_ts(tp); |
233 | return 0; |
234 | } |
235 | |
236 | /* |
237 | * Get monotonic time for posix timers |
238 | */ |
239 | static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp) |
240 | { |
241 | getrawmonotonic(tp); |
242 | return 0; |
243 | } |
244 | |
245 | |
246 | static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp) |
247 | { |
248 | *tp = current_kernel_time(); |
249 | return 0; |
250 | } |
251 | |
252 | static int posix_get_monotonic_coarse(clockid_t which_clock, |
253 | struct timespec *tp) |
254 | { |
255 | *tp = get_monotonic_coarse(); |
256 | return 0; |
257 | } |
258 | |
259 | static int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp) |
260 | { |
261 | *tp = ktime_to_timespec(KTIME_LOW_RES); |
262 | return 0; |
263 | } |
264 | /* |
265 | * Initialize everything, well, just everything in Posix clocks/timers ;) |
266 | */ |
267 | static __init int init_posix_timers(void) |
268 | { |
269 | struct k_clock clock_realtime = { |
270 | .clock_getres = hrtimer_get_res, |
271 | }; |
272 | struct k_clock clock_monotonic = { |
273 | .clock_getres = hrtimer_get_res, |
274 | .clock_get = posix_ktime_get_ts, |
275 | .clock_set = do_posix_clock_nosettime, |
276 | }; |
277 | struct k_clock clock_monotonic_raw = { |
278 | .clock_getres = hrtimer_get_res, |
279 | .clock_get = posix_get_monotonic_raw, |
280 | .clock_set = do_posix_clock_nosettime, |
281 | .timer_create = no_timer_create, |
282 | .nsleep = no_nsleep, |
283 | }; |
284 | struct k_clock clock_realtime_coarse = { |
285 | .clock_getres = posix_get_coarse_res, |
286 | .clock_get = posix_get_realtime_coarse, |
287 | .clock_set = do_posix_clock_nosettime, |
288 | .timer_create = no_timer_create, |
289 | .nsleep = no_nsleep, |
290 | }; |
291 | struct k_clock clock_monotonic_coarse = { |
292 | .clock_getres = posix_get_coarse_res, |
293 | .clock_get = posix_get_monotonic_coarse, |
294 | .clock_set = do_posix_clock_nosettime, |
295 | .timer_create = no_timer_create, |
296 | .nsleep = no_nsleep, |
297 | }; |
298 | |
299 | register_posix_clock(CLOCK_REALTIME, &clock_realtime); |
300 | register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic); |
301 | register_posix_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw); |
302 | register_posix_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse); |
303 | register_posix_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse); |
304 | |
305 | posix_timers_cache = kmem_cache_create("posix_timers_cache", |
306 | sizeof (struct k_itimer), 0, SLAB_PANIC, |
307 | NULL); |
308 | idr_init(&posix_timers_id); |
309 | return 0; |
310 | } |
311 | |
312 | __initcall(init_posix_timers); |
313 | |
314 | static void schedule_next_timer(struct k_itimer *timr) |
315 | { |
316 | struct hrtimer *timer = &timr->it.real.timer; |
317 | |
318 | if (timr->it.real.interval.tv64 == 0) |
319 | return; |
320 | |
321 | timr->it_overrun += (unsigned int) hrtimer_forward(timer, |
322 | timer->base->get_time(), |
323 | timr->it.real.interval); |
324 | |
325 | timr->it_overrun_last = timr->it_overrun; |
326 | timr->it_overrun = -1; |
327 | ++timr->it_requeue_pending; |
328 | hrtimer_restart(timer); |
329 | } |
330 | |
331 | /* |
332 | * This function is exported for use by the signal deliver code. It is |
333 | * called just prior to the info block being released and passes that |
334 | * block to us. It's function is to update the overrun entry AND to |
335 | * restart the timer. It should only be called if the timer is to be |
336 | * restarted (i.e. we have flagged this in the sys_private entry of the |
337 | * info block). |
338 | * |
339 | * To protect aginst the timer going away while the interrupt is queued, |
340 | * we require that the it_requeue_pending flag be set. |
341 | */ |
342 | void do_schedule_next_timer(struct siginfo *info) |
343 | { |
344 | struct k_itimer *timr; |
345 | unsigned long flags; |
346 | |
347 | timr = lock_timer(info->si_tid, &flags); |
348 | |
349 | if (timr && timr->it_requeue_pending == info->si_sys_private) { |
350 | if (timr->it_clock < 0) |
351 | posix_cpu_timer_schedule(timr); |
352 | else |
353 | schedule_next_timer(timr); |
354 | |
355 | info->si_overrun += timr->it_overrun_last; |
356 | } |
357 | |
358 | if (timr) |
359 | unlock_timer(timr, flags); |
360 | } |
361 | |
362 | int posix_timer_event(struct k_itimer *timr, int si_private) |
363 | { |
364 | struct task_struct *task; |
365 | int shared, ret = -1; |
366 | /* |
367 | * FIXME: if ->sigq is queued we can race with |
368 | * dequeue_signal()->do_schedule_next_timer(). |
369 | * |
370 | * If dequeue_signal() sees the "right" value of |
371 | * si_sys_private it calls do_schedule_next_timer(). |
372 | * We re-queue ->sigq and drop ->it_lock(). |
373 | * do_schedule_next_timer() locks the timer |
374 | * and re-schedules it while ->sigq is pending. |
375 | * Not really bad, but not that we want. |
376 | */ |
377 | timr->sigq->info.si_sys_private = si_private; |
378 | |
379 | rcu_read_lock(); |
380 | task = pid_task(timr->it_pid, PIDTYPE_PID); |
381 | if (task) { |
382 | shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID); |
383 | ret = send_sigqueue(timr->sigq, task, shared); |
384 | } |
385 | rcu_read_unlock(); |
386 | /* If we failed to send the signal the timer stops. */ |
387 | return ret > 0; |
388 | } |
389 | EXPORT_SYMBOL_GPL(posix_timer_event); |
390 | |
391 | /* |
392 | * This function gets called when a POSIX.1b interval timer expires. It |
393 | * is used as a callback from the kernel internal timer. The |
394 | * run_timer_list code ALWAYS calls with interrupts on. |
395 | |
396 | * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers. |
397 | */ |
398 | static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer) |
399 | { |
400 | struct k_itimer *timr; |
401 | unsigned long flags; |
402 | int si_private = 0; |
403 | enum hrtimer_restart ret = HRTIMER_NORESTART; |
404 | |
405 | timr = container_of(timer, struct k_itimer, it.real.timer); |
406 | spin_lock_irqsave(&timr->it_lock, flags); |
407 | |
408 | if (timr->it.real.interval.tv64 != 0) |
409 | si_private = ++timr->it_requeue_pending; |
410 | |
411 | if (posix_timer_event(timr, si_private)) { |
412 | /* |
413 | * signal was not sent because of sig_ignor |
414 | * we will not get a call back to restart it AND |
415 | * it should be restarted. |
416 | */ |
417 | if (timr->it.real.interval.tv64 != 0) { |
418 | ktime_t now = hrtimer_cb_get_time(timer); |
419 | |
420 | /* |
421 | * FIXME: What we really want, is to stop this |
422 | * timer completely and restart it in case the |
423 | * SIG_IGN is removed. This is a non trivial |
424 | * change which involves sighand locking |
425 | * (sigh !), which we don't want to do late in |
426 | * the release cycle. |
427 | * |
428 | * For now we just let timers with an interval |
429 | * less than a jiffie expire every jiffie to |
430 | * avoid softirq starvation in case of SIG_IGN |
431 | * and a very small interval, which would put |
432 | * the timer right back on the softirq pending |
433 | * list. By moving now ahead of time we trick |
434 | * hrtimer_forward() to expire the timer |
435 | * later, while we still maintain the overrun |
436 | * accuracy, but have some inconsistency in |
437 | * the timer_gettime() case. This is at least |
438 | * better than a starved softirq. A more |
439 | * complex fix which solves also another related |
440 | * inconsistency is already in the pipeline. |
441 | */ |
442 | #ifdef CONFIG_HIGH_RES_TIMERS |
443 | { |
444 | ktime_t kj = ktime_set(0, NSEC_PER_SEC / HZ); |
445 | |
446 | if (timr->it.real.interval.tv64 < kj.tv64) |
447 | now = ktime_add(now, kj); |
448 | } |
449 | #endif |
450 | timr->it_overrun += (unsigned int) |
451 | hrtimer_forward(timer, now, |
452 | timr->it.real.interval); |
453 | ret = HRTIMER_RESTART; |
454 | ++timr->it_requeue_pending; |
455 | } |
456 | } |
457 | |
458 | unlock_timer(timr, flags); |
459 | return ret; |
460 | } |
461 | |
462 | static struct pid *good_sigevent(sigevent_t * event) |
463 | { |
464 | struct task_struct *rtn = current->group_leader; |
465 | |
466 | if ((event->sigev_notify & SIGEV_THREAD_ID ) && |
467 | (!(rtn = find_task_by_vpid(event->sigev_notify_thread_id)) || |
468 | !same_thread_group(rtn, current) || |
469 | (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL)) |
470 | return NULL; |
471 | |
472 | if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) && |
473 | ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX))) |
474 | return NULL; |
475 | |
476 | return task_pid(rtn); |
477 | } |
478 | |
479 | void register_posix_clock(const clockid_t clock_id, struct k_clock *new_clock) |
480 | { |
481 | if ((unsigned) clock_id >= MAX_CLOCKS) { |
482 | printk("POSIX clock register failed for clock_id %d\n", |
483 | clock_id); |
484 | return; |
485 | } |
486 | |
487 | posix_clocks[clock_id] = *new_clock; |
488 | } |
489 | EXPORT_SYMBOL_GPL(register_posix_clock); |
490 | |
491 | static struct k_itimer * alloc_posix_timer(void) |
492 | { |
493 | struct k_itimer *tmr; |
494 | tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL); |
495 | if (!tmr) |
496 | return tmr; |
497 | if (unlikely(!(tmr->sigq = sigqueue_alloc()))) { |
498 | kmem_cache_free(posix_timers_cache, tmr); |
499 | return NULL; |
500 | } |
501 | memset(&tmr->sigq->info, 0, sizeof(siginfo_t)); |
502 | return tmr; |
503 | } |
504 | |
505 | #define IT_ID_SET 1 |
506 | #define IT_ID_NOT_SET 0 |
507 | static void release_posix_timer(struct k_itimer *tmr, int it_id_set) |
508 | { |
509 | if (it_id_set) { |
510 | unsigned long flags; |
511 | spin_lock_irqsave(&idr_lock, flags); |
512 | idr_remove(&posix_timers_id, tmr->it_id); |
513 | spin_unlock_irqrestore(&idr_lock, flags); |
514 | } |
515 | put_pid(tmr->it_pid); |
516 | sigqueue_free(tmr->sigq); |
517 | kmem_cache_free(posix_timers_cache, tmr); |
518 | } |
519 | |
520 | /* Create a POSIX.1b interval timer. */ |
521 | |
522 | SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock, |
523 | struct sigevent __user *, timer_event_spec, |
524 | timer_t __user *, created_timer_id) |
525 | { |
526 | struct k_itimer *new_timer; |
527 | int error, new_timer_id; |
528 | sigevent_t event; |
529 | int it_id_set = IT_ID_NOT_SET; |
530 | |
531 | if (invalid_clockid(which_clock)) |
532 | return -EINVAL; |
533 | |
534 | new_timer = alloc_posix_timer(); |
535 | if (unlikely(!new_timer)) |
536 | return -EAGAIN; |
537 | |
538 | spin_lock_init(&new_timer->it_lock); |
539 | retry: |
540 | if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) { |
541 | error = -EAGAIN; |
542 | goto out; |
543 | } |
544 | spin_lock_irq(&idr_lock); |
545 | error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id); |
546 | spin_unlock_irq(&idr_lock); |
547 | if (error) { |
548 | if (error == -EAGAIN) |
549 | goto retry; |
550 | /* |
551 | * Weird looking, but we return EAGAIN if the IDR is |
552 | * full (proper POSIX return value for this) |
553 | */ |
554 | error = -EAGAIN; |
555 | goto out; |
556 | } |
557 | |
558 | it_id_set = IT_ID_SET; |
559 | new_timer->it_id = (timer_t) new_timer_id; |
560 | new_timer->it_clock = which_clock; |
561 | new_timer->it_overrun = -1; |
562 | error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer)); |
563 | if (error) |
564 | goto out; |
565 | |
566 | /* |
567 | * return the timer_id now. The next step is hard to |
568 | * back out if there is an error. |
569 | */ |
570 | if (copy_to_user(created_timer_id, |
571 | &new_timer_id, sizeof (new_timer_id))) { |
572 | error = -EFAULT; |
573 | goto out; |
574 | } |
575 | if (timer_event_spec) { |
576 | if (copy_from_user(&event, timer_event_spec, sizeof (event))) { |
577 | error = -EFAULT; |
578 | goto out; |
579 | } |
580 | rcu_read_lock(); |
581 | new_timer->it_pid = get_pid(good_sigevent(&event)); |
582 | rcu_read_unlock(); |
583 | if (!new_timer->it_pid) { |
584 | error = -EINVAL; |
585 | goto out; |
586 | } |
587 | } else { |
588 | event.sigev_notify = SIGEV_SIGNAL; |
589 | event.sigev_signo = SIGALRM; |
590 | event.sigev_value.sival_int = new_timer->it_id; |
591 | new_timer->it_pid = get_pid(task_tgid(current)); |
592 | } |
593 | |
594 | new_timer->it_sigev_notify = event.sigev_notify; |
595 | new_timer->sigq->info.si_signo = event.sigev_signo; |
596 | new_timer->sigq->info.si_value = event.sigev_value; |
597 | new_timer->sigq->info.si_tid = new_timer->it_id; |
598 | new_timer->sigq->info.si_code = SI_TIMER; |
599 | |
600 | spin_lock_irq(¤t->sighand->siglock); |
601 | new_timer->it_signal = current->signal; |
602 | list_add(&new_timer->list, ¤t->signal->posix_timers); |
603 | spin_unlock_irq(¤t->sighand->siglock); |
604 | |
605 | return 0; |
606 | /* |
607 | * In the case of the timer belonging to another task, after |
608 | * the task is unlocked, the timer is owned by the other task |
609 | * and may cease to exist at any time. Don't use or modify |
610 | * new_timer after the unlock call. |
611 | */ |
612 | out: |
613 | release_posix_timer(new_timer, it_id_set); |
614 | return error; |
615 | } |
616 | |
617 | /* |
618 | * Locking issues: We need to protect the result of the id look up until |
619 | * we get the timer locked down so it is not deleted under us. The |
620 | * removal is done under the idr spinlock so we use that here to bridge |
621 | * the find to the timer lock. To avoid a dead lock, the timer id MUST |
622 | * be release with out holding the timer lock. |
623 | */ |
624 | static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags) |
625 | { |
626 | struct k_itimer *timr; |
627 | /* |
628 | * Watch out here. We do a irqsave on the idr_lock and pass the |
629 | * flags part over to the timer lock. Must not let interrupts in |
630 | * while we are moving the lock. |
631 | */ |
632 | spin_lock_irqsave(&idr_lock, *flags); |
633 | timr = idr_find(&posix_timers_id, (int)timer_id); |
634 | if (timr) { |
635 | spin_lock(&timr->it_lock); |
636 | if (timr->it_signal == current->signal) { |
637 | spin_unlock(&idr_lock); |
638 | return timr; |
639 | } |
640 | spin_unlock(&timr->it_lock); |
641 | } |
642 | spin_unlock_irqrestore(&idr_lock, *flags); |
643 | |
644 | return NULL; |
645 | } |
646 | |
647 | /* |
648 | * Get the time remaining on a POSIX.1b interval timer. This function |
649 | * is ALWAYS called with spin_lock_irq on the timer, thus it must not |
650 | * mess with irq. |
651 | * |
652 | * We have a couple of messes to clean up here. First there is the case |
653 | * of a timer that has a requeue pending. These timers should appear to |
654 | * be in the timer list with an expiry as if we were to requeue them |
655 | * now. |
656 | * |
657 | * The second issue is the SIGEV_NONE timer which may be active but is |
658 | * not really ever put in the timer list (to save system resources). |
659 | * This timer may be expired, and if so, we will do it here. Otherwise |
660 | * it is the same as a requeue pending timer WRT to what we should |
661 | * report. |
662 | */ |
663 | static void |
664 | common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting) |
665 | { |
666 | ktime_t now, remaining, iv; |
667 | struct hrtimer *timer = &timr->it.real.timer; |
668 | |
669 | memset(cur_setting, 0, sizeof(struct itimerspec)); |
670 | |
671 | iv = timr->it.real.interval; |
672 | |
673 | /* interval timer ? */ |
674 | if (iv.tv64) |
675 | cur_setting->it_interval = ktime_to_timespec(iv); |
676 | else if (!hrtimer_active(timer) && |
677 | (timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) |
678 | return; |
679 | |
680 | now = timer->base->get_time(); |
681 | |
682 | /* |
683 | * When a requeue is pending or this is a SIGEV_NONE |
684 | * timer move the expiry time forward by intervals, so |
685 | * expiry is > now. |
686 | */ |
687 | if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING || |
688 | (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) |
689 | timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv); |
690 | |
691 | remaining = ktime_sub(hrtimer_get_expires(timer), now); |
692 | /* Return 0 only, when the timer is expired and not pending */ |
693 | if (remaining.tv64 <= 0) { |
694 | /* |
695 | * A single shot SIGEV_NONE timer must return 0, when |
696 | * it is expired ! |
697 | */ |
698 | if ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) |
699 | cur_setting->it_value.tv_nsec = 1; |
700 | } else |
701 | cur_setting->it_value = ktime_to_timespec(remaining); |
702 | } |
703 | |
704 | /* Get the time remaining on a POSIX.1b interval timer. */ |
705 | SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id, |
706 | struct itimerspec __user *, setting) |
707 | { |
708 | struct k_itimer *timr; |
709 | struct itimerspec cur_setting; |
710 | unsigned long flags; |
711 | |
712 | timr = lock_timer(timer_id, &flags); |
713 | if (!timr) |
714 | return -EINVAL; |
715 | |
716 | CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting)); |
717 | |
718 | unlock_timer(timr, flags); |
719 | |
720 | if (copy_to_user(setting, &cur_setting, sizeof (cur_setting))) |
721 | return -EFAULT; |
722 | |
723 | return 0; |
724 | } |
725 | |
726 | /* |
727 | * Get the number of overruns of a POSIX.1b interval timer. This is to |
728 | * be the overrun of the timer last delivered. At the same time we are |
729 | * accumulating overruns on the next timer. The overrun is frozen when |
730 | * the signal is delivered, either at the notify time (if the info block |
731 | * is not queued) or at the actual delivery time (as we are informed by |
732 | * the call back to do_schedule_next_timer(). So all we need to do is |
733 | * to pick up the frozen overrun. |
734 | */ |
735 | SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id) |
736 | { |
737 | struct k_itimer *timr; |
738 | int overrun; |
739 | unsigned long flags; |
740 | |
741 | timr = lock_timer(timer_id, &flags); |
742 | if (!timr) |
743 | return -EINVAL; |
744 | |
745 | overrun = timr->it_overrun_last; |
746 | unlock_timer(timr, flags); |
747 | |
748 | return overrun; |
749 | } |
750 | |
751 | /* Set a POSIX.1b interval timer. */ |
752 | /* timr->it_lock is taken. */ |
753 | static int |
754 | common_timer_set(struct k_itimer *timr, int flags, |
755 | struct itimerspec *new_setting, struct itimerspec *old_setting) |
756 | { |
757 | struct hrtimer *timer = &timr->it.real.timer; |
758 | enum hrtimer_mode mode; |
759 | |
760 | if (old_setting) |
761 | common_timer_get(timr, old_setting); |
762 | |
763 | /* disable the timer */ |
764 | timr->it.real.interval.tv64 = 0; |
765 | /* |
766 | * careful here. If smp we could be in the "fire" routine which will |
767 | * be spinning as we hold the lock. But this is ONLY an SMP issue. |
768 | */ |
769 | if (hrtimer_try_to_cancel(timer) < 0) |
770 | return TIMER_RETRY; |
771 | |
772 | timr->it_requeue_pending = (timr->it_requeue_pending + 2) & |
773 | ~REQUEUE_PENDING; |
774 | timr->it_overrun_last = 0; |
775 | |
776 | /* switch off the timer when it_value is zero */ |
777 | if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec) |
778 | return 0; |
779 | |
780 | mode = flags & TIMER_ABSTIME ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL; |
781 | hrtimer_init(&timr->it.real.timer, timr->it_clock, mode); |
782 | timr->it.real.timer.function = posix_timer_fn; |
783 | |
784 | hrtimer_set_expires(timer, timespec_to_ktime(new_setting->it_value)); |
785 | |
786 | /* Convert interval */ |
787 | timr->it.real.interval = timespec_to_ktime(new_setting->it_interval); |
788 | |
789 | /* SIGEV_NONE timers are not queued ! See common_timer_get */ |
790 | if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) { |
791 | /* Setup correct expiry time for relative timers */ |
792 | if (mode == HRTIMER_MODE_REL) { |
793 | hrtimer_add_expires(timer, timer->base->get_time()); |
794 | } |
795 | return 0; |
796 | } |
797 | |
798 | hrtimer_start_expires(timer, mode); |
799 | return 0; |
800 | } |
801 | |
802 | /* Set a POSIX.1b interval timer */ |
803 | SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags, |
804 | const struct itimerspec __user *, new_setting, |
805 | struct itimerspec __user *, old_setting) |
806 | { |
807 | struct k_itimer *timr; |
808 | struct itimerspec new_spec, old_spec; |
809 | int error = 0; |
810 | unsigned long flag; |
811 | struct itimerspec *rtn = old_setting ? &old_spec : NULL; |
812 | |
813 | if (!new_setting) |
814 | return -EINVAL; |
815 | |
816 | if (copy_from_user(&new_spec, new_setting, sizeof (new_spec))) |
817 | return -EFAULT; |
818 | |
819 | if (!timespec_valid(&new_spec.it_interval) || |
820 | !timespec_valid(&new_spec.it_value)) |
821 | return -EINVAL; |
822 | retry: |
823 | timr = lock_timer(timer_id, &flag); |
824 | if (!timr) |
825 | return -EINVAL; |
826 | |
827 | error = CLOCK_DISPATCH(timr->it_clock, timer_set, |
828 | (timr, flags, &new_spec, rtn)); |
829 | |
830 | unlock_timer(timr, flag); |
831 | if (error == TIMER_RETRY) { |
832 | rtn = NULL; // We already got the old time... |
833 | goto retry; |
834 | } |
835 | |
836 | if (old_setting && !error && |
837 | copy_to_user(old_setting, &old_spec, sizeof (old_spec))) |
838 | error = -EFAULT; |
839 | |
840 | return error; |
841 | } |
842 | |
843 | static inline int common_timer_del(struct k_itimer *timer) |
844 | { |
845 | timer->it.real.interval.tv64 = 0; |
846 | |
847 | if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0) |
848 | return TIMER_RETRY; |
849 | return 0; |
850 | } |
851 | |
852 | static inline int timer_delete_hook(struct k_itimer *timer) |
853 | { |
854 | return CLOCK_DISPATCH(timer->it_clock, timer_del, (timer)); |
855 | } |
856 | |
857 | /* Delete a POSIX.1b interval timer. */ |
858 | SYSCALL_DEFINE1(timer_delete, timer_t, timer_id) |
859 | { |
860 | struct k_itimer *timer; |
861 | unsigned long flags; |
862 | |
863 | retry_delete: |
864 | timer = lock_timer(timer_id, &flags); |
865 | if (!timer) |
866 | return -EINVAL; |
867 | |
868 | if (timer_delete_hook(timer) == TIMER_RETRY) { |
869 | unlock_timer(timer, flags); |
870 | goto retry_delete; |
871 | } |
872 | |
873 | spin_lock(¤t->sighand->siglock); |
874 | list_del(&timer->list); |
875 | spin_unlock(¤t->sighand->siglock); |
876 | /* |
877 | * This keeps any tasks waiting on the spin lock from thinking |
878 | * they got something (see the lock code above). |
879 | */ |
880 | timer->it_signal = NULL; |
881 | |
882 | unlock_timer(timer, flags); |
883 | release_posix_timer(timer, IT_ID_SET); |
884 | return 0; |
885 | } |
886 | |
887 | /* |
888 | * return timer owned by the process, used by exit_itimers |
889 | */ |
890 | static void itimer_delete(struct k_itimer *timer) |
891 | { |
892 | unsigned long flags; |
893 | |
894 | retry_delete: |
895 | spin_lock_irqsave(&timer->it_lock, flags); |
896 | |
897 | if (timer_delete_hook(timer) == TIMER_RETRY) { |
898 | unlock_timer(timer, flags); |
899 | goto retry_delete; |
900 | } |
901 | list_del(&timer->list); |
902 | /* |
903 | * This keeps any tasks waiting on the spin lock from thinking |
904 | * they got something (see the lock code above). |
905 | */ |
906 | timer->it_signal = NULL; |
907 | |
908 | unlock_timer(timer, flags); |
909 | release_posix_timer(timer, IT_ID_SET); |
910 | } |
911 | |
912 | /* |
913 | * This is called by do_exit or de_thread, only when there are no more |
914 | * references to the shared signal_struct. |
915 | */ |
916 | void exit_itimers(struct signal_struct *sig) |
917 | { |
918 | struct k_itimer *tmr; |
919 | |
920 | while (!list_empty(&sig->posix_timers)) { |
921 | tmr = list_entry(sig->posix_timers.next, struct k_itimer, list); |
922 | itimer_delete(tmr); |
923 | } |
924 | } |
925 | |
926 | /* Not available / possible... functions */ |
927 | int do_posix_clock_nosettime(const clockid_t clockid, struct timespec *tp) |
928 | { |
929 | return -EINVAL; |
930 | } |
931 | EXPORT_SYMBOL_GPL(do_posix_clock_nosettime); |
932 | |
933 | int do_posix_clock_nonanosleep(const clockid_t clock, int flags, |
934 | struct timespec *t, struct timespec __user *r) |
935 | { |
936 | #ifndef ENOTSUP |
937 | return -EOPNOTSUPP; /* aka ENOTSUP in userland for POSIX */ |
938 | #else /* parisc does define it separately. */ |
939 | return -ENOTSUP; |
940 | #endif |
941 | } |
942 | EXPORT_SYMBOL_GPL(do_posix_clock_nonanosleep); |
943 | |
944 | SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock, |
945 | const struct timespec __user *, tp) |
946 | { |
947 | struct timespec new_tp; |
948 | |
949 | if (invalid_clockid(which_clock)) |
950 | return -EINVAL; |
951 | if (copy_from_user(&new_tp, tp, sizeof (*tp))) |
952 | return -EFAULT; |
953 | |
954 | return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp)); |
955 | } |
956 | |
957 | SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock, |
958 | struct timespec __user *,tp) |
959 | { |
960 | struct timespec kernel_tp; |
961 | int error; |
962 | |
963 | if (invalid_clockid(which_clock)) |
964 | return -EINVAL; |
965 | error = CLOCK_DISPATCH(which_clock, clock_get, |
966 | (which_clock, &kernel_tp)); |
967 | if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp))) |
968 | error = -EFAULT; |
969 | |
970 | return error; |
971 | |
972 | } |
973 | |
974 | SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock, |
975 | struct timespec __user *, tp) |
976 | { |
977 | struct timespec rtn_tp; |
978 | int error; |
979 | |
980 | if (invalid_clockid(which_clock)) |
981 | return -EINVAL; |
982 | |
983 | error = CLOCK_DISPATCH(which_clock, clock_getres, |
984 | (which_clock, &rtn_tp)); |
985 | |
986 | if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp))) { |
987 | error = -EFAULT; |
988 | } |
989 | |
990 | return error; |
991 | } |
992 | |
993 | /* |
994 | * nanosleep for monotonic and realtime clocks |
995 | */ |
996 | static int common_nsleep(const clockid_t which_clock, int flags, |
997 | struct timespec *tsave, struct timespec __user *rmtp) |
998 | { |
999 | return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ? |
1000 | HRTIMER_MODE_ABS : HRTIMER_MODE_REL, |
1001 | which_clock); |
1002 | } |
1003 | |
1004 | SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags, |
1005 | const struct timespec __user *, rqtp, |
1006 | struct timespec __user *, rmtp) |
1007 | { |
1008 | struct timespec t; |
1009 | |
1010 | if (invalid_clockid(which_clock)) |
1011 | return -EINVAL; |
1012 | |
1013 | if (copy_from_user(&t, rqtp, sizeof (struct timespec))) |
1014 | return -EFAULT; |
1015 | |
1016 | if (!timespec_valid(&t)) |
1017 | return -EINVAL; |
1018 | |
1019 | return CLOCK_DISPATCH(which_clock, nsleep, |
1020 | (which_clock, flags, &t, rmtp)); |
1021 | } |
1022 | |
1023 | /* |
1024 | * nanosleep_restart for monotonic and realtime clocks |
1025 | */ |
1026 | static int common_nsleep_restart(struct restart_block *restart_block) |
1027 | { |
1028 | return hrtimer_nanosleep_restart(restart_block); |
1029 | } |
1030 | |
1031 | /* |
1032 | * This will restart clock_nanosleep. This is required only by |
1033 | * compat_clock_nanosleep_restart for now. |
1034 | */ |
1035 | long |
1036 | clock_nanosleep_restart(struct restart_block *restart_block) |
1037 | { |
1038 | clockid_t which_clock = restart_block->arg0; |
1039 | |
1040 | return CLOCK_DISPATCH(which_clock, nsleep_restart, |
1041 | (restart_block)); |
1042 | } |
1043 |
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Tags:
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od-2011-09-18
v2.6.34-rc5
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