~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/kernel/time/posix-timers.c

Version: ~ [ linux-5.4-rc3 ] ~ [ linux-5.3.6 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.79 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.149 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.196 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.196 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.75 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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/hash.h>
 44 #include <linux/posix-clock.h>
 45 #include <linux/posix-timers.h>
 46 #include <linux/syscalls.h>
 47 #include <linux/wait.h>
 48 #include <linux/workqueue.h>
 49 #include <linux/export.h>
 50 #include <linux/hashtable.h>
 51 
 52 #include "timekeeping.h"
 53 
 54 /*
 55  * Management arrays for POSIX timers. Timers are now kept in static hash table
 56  * with 512 entries.
 57  * Timer ids are allocated by local routine, which selects proper hash head by
 58  * key, constructed from current->signal address and per signal struct counter.
 59  * This keeps timer ids unique per process, but now they can intersect between
 60  * processes.
 61  */
 62 
 63 /*
 64  * Lets keep our timers in a slab cache :-)
 65  */
 66 static struct kmem_cache *posix_timers_cache;
 67 
 68 static DEFINE_HASHTABLE(posix_timers_hashtable, 9);
 69 static DEFINE_SPINLOCK(hash_lock);
 70 
 71 /*
 72  * we assume that the new SIGEV_THREAD_ID shares no bits with the other
 73  * SIGEV values.  Here we put out an error if this assumption fails.
 74  */
 75 #if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
 76                        ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
 77 #error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
 78 #endif
 79 
 80 /*
 81  * parisc wants ENOTSUP instead of EOPNOTSUPP
 82  */
 83 #ifndef ENOTSUP
 84 # define ENANOSLEEP_NOTSUP EOPNOTSUPP
 85 #else
 86 # define ENANOSLEEP_NOTSUP ENOTSUP
 87 #endif
 88 
 89 /*
 90  * The timer ID is turned into a timer address by idr_find().
 91  * Verifying a valid ID consists of:
 92  *
 93  * a) checking that idr_find() returns other than -1.
 94  * b) checking that the timer id matches the one in the timer itself.
 95  * c) that the timer owner is in the callers thread group.
 96  */
 97 
 98 /*
 99  * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
100  *          to implement others.  This structure defines the various
101  *          clocks.
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
112  *          handle various clock functions.
113  *
114  *          The standard POSIX timer management code assumes the
115  *          following: 1.) The k_itimer struct (sched.h) is used for
116  *          the timer.  2.) The list, it_lock, it_clock, it_id and
117  *          it_pid fields are not modified by timer code.
118  *
119  * Permissions: It is assumed that the clock_settime() function defined
120  *          for each clock will take care of permission checks.  Some
121  *          clocks may be set able by any user (i.e. local process
122  *          clocks) others not.  Currently the only set able clock we
123  *          have is CLOCK_REALTIME and its high res counter part, both of
124  *          which we beg off on and pass to do_sys_settimeofday().
125  */
126 
127 static struct k_clock posix_clocks[MAX_CLOCKS];
128 
129 /*
130  * These ones are defined below.
131  */
132 static int common_nsleep(const clockid_t, int flags, struct timespec *t,
133                          struct timespec __user *rmtp);
134 static int common_timer_create(struct k_itimer *new_timer);
135 static void common_timer_get(struct k_itimer *, struct itimerspec *);
136 static int common_timer_set(struct k_itimer *, int,
137                             struct itimerspec *, struct itimerspec *);
138 static int common_timer_del(struct k_itimer *timer);
139 
140 static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
141 
142 static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
143 
144 #define lock_timer(tid, flags)                                             \
145 ({      struct k_itimer *__timr;                                           \
146         __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags));  \
147         __timr;                                                            \
148 })
149 
150 static int hash(struct signal_struct *sig, unsigned int nr)
151 {
152         return hash_32(hash32_ptr(sig) ^ nr, HASH_BITS(posix_timers_hashtable));
153 }
154 
155 static struct k_itimer *__posix_timers_find(struct hlist_head *head,
156                                             struct signal_struct *sig,
157                                             timer_t id)
158 {
159         struct k_itimer *timer;
160 
161         hlist_for_each_entry_rcu(timer, head, t_hash) {
162                 if ((timer->it_signal == sig) && (timer->it_id == id))
163                         return timer;
164         }
165         return NULL;
166 }
167 
168 static struct k_itimer *posix_timer_by_id(timer_t id)
169 {
170         struct signal_struct *sig = current->signal;
171         struct hlist_head *head = &posix_timers_hashtable[hash(sig, id)];
172 
173         return __posix_timers_find(head, sig, id);
174 }
175 
176 static int posix_timer_add(struct k_itimer *timer)
177 {
178         struct signal_struct *sig = current->signal;
179         int first_free_id = sig->posix_timer_id;
180         struct hlist_head *head;
181         int ret = -ENOENT;
182 
183         do {
184                 spin_lock(&hash_lock);
185                 head = &posix_timers_hashtable[hash(sig, sig->posix_timer_id)];
186                 if (!__posix_timers_find(head, sig, sig->posix_timer_id)) {
187                         hlist_add_head_rcu(&timer->t_hash, head);
188                         ret = sig->posix_timer_id;
189                 }
190                 if (++sig->posix_timer_id < 0)
191                         sig->posix_timer_id = 0;
192                 if ((sig->posix_timer_id == first_free_id) && (ret == -ENOENT))
193                         /* Loop over all possible ids completed */
194                         ret = -EAGAIN;
195                 spin_unlock(&hash_lock);
196         } while (ret == -ENOENT);
197         return ret;
198 }
199 
200 static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
201 {
202         spin_unlock_irqrestore(&timr->it_lock, flags);
203 }
204 
205 /* Get clock_realtime */
206 static int posix_clock_realtime_get(clockid_t which_clock, struct timespec *tp)
207 {
208         ktime_get_real_ts(tp);
209         return 0;
210 }
211 
212 /* Set clock_realtime */
213 static int posix_clock_realtime_set(const clockid_t which_clock,
214                                     const struct timespec *tp)
215 {
216         return do_sys_settimeofday(tp, NULL);
217 }
218 
219 static int posix_clock_realtime_adj(const clockid_t which_clock,
220                                     struct timex *t)
221 {
222         return do_adjtimex(t);
223 }
224 
225 /*
226  * Get monotonic time for posix timers
227  */
228 static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
229 {
230         ktime_get_ts(tp);
231         return 0;
232 }
233 
234 /*
235  * Get monotonic-raw time for posix timers
236  */
237 static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
238 {
239         getrawmonotonic(tp);
240         return 0;
241 }
242 
243 
244 static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp)
245 {
246         *tp = current_kernel_time();
247         return 0;
248 }
249 
250 static int posix_get_monotonic_coarse(clockid_t which_clock,
251                                                 struct timespec *tp)
252 {
253         *tp = get_monotonic_coarse();
254         return 0;
255 }
256 
257 static int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp)
258 {
259         *tp = ktime_to_timespec(KTIME_LOW_RES);
260         return 0;
261 }
262 
263 static int posix_get_boottime(const clockid_t which_clock, struct timespec *tp)
264 {
265         get_monotonic_boottime(tp);
266         return 0;
267 }
268 
269 static int posix_get_tai(clockid_t which_clock, struct timespec *tp)
270 {
271         timekeeping_clocktai(tp);
272         return 0;
273 }
274 
275 static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec *tp)
276 {
277         tp->tv_sec = 0;
278         tp->tv_nsec = hrtimer_resolution;
279         return 0;
280 }
281 
282 /*
283  * Initialize everything, well, just everything in Posix clocks/timers ;)
284  */
285 static __init int init_posix_timers(void)
286 {
287         struct k_clock clock_realtime = {
288                 .clock_getres   = posix_get_hrtimer_res,
289                 .clock_get      = posix_clock_realtime_get,
290                 .clock_set      = posix_clock_realtime_set,
291                 .clock_adj      = posix_clock_realtime_adj,
292                 .nsleep         = common_nsleep,
293                 .nsleep_restart = hrtimer_nanosleep_restart,
294                 .timer_create   = common_timer_create,
295                 .timer_set      = common_timer_set,
296                 .timer_get      = common_timer_get,
297                 .timer_del      = common_timer_del,
298         };
299         struct k_clock clock_monotonic = {
300                 .clock_getres   = posix_get_hrtimer_res,
301                 .clock_get      = posix_ktime_get_ts,
302                 .nsleep         = common_nsleep,
303                 .nsleep_restart = hrtimer_nanosleep_restart,
304                 .timer_create   = common_timer_create,
305                 .timer_set      = common_timer_set,
306                 .timer_get      = common_timer_get,
307                 .timer_del      = common_timer_del,
308         };
309         struct k_clock clock_monotonic_raw = {
310                 .clock_getres   = posix_get_hrtimer_res,
311                 .clock_get      = posix_get_monotonic_raw,
312         };
313         struct k_clock clock_realtime_coarse = {
314                 .clock_getres   = posix_get_coarse_res,
315                 .clock_get      = posix_get_realtime_coarse,
316         };
317         struct k_clock clock_monotonic_coarse = {
318                 .clock_getres   = posix_get_coarse_res,
319                 .clock_get      = posix_get_monotonic_coarse,
320         };
321         struct k_clock clock_tai = {
322                 .clock_getres   = posix_get_hrtimer_res,
323                 .clock_get      = posix_get_tai,
324                 .nsleep         = common_nsleep,
325                 .nsleep_restart = hrtimer_nanosleep_restart,
326                 .timer_create   = common_timer_create,
327                 .timer_set      = common_timer_set,
328                 .timer_get      = common_timer_get,
329                 .timer_del      = common_timer_del,
330         };
331         struct k_clock clock_boottime = {
332                 .clock_getres   = posix_get_hrtimer_res,
333                 .clock_get      = posix_get_boottime,
334                 .nsleep         = common_nsleep,
335                 .nsleep_restart = hrtimer_nanosleep_restart,
336                 .timer_create   = common_timer_create,
337                 .timer_set      = common_timer_set,
338                 .timer_get      = common_timer_get,
339                 .timer_del      = common_timer_del,
340         };
341 
342         posix_timers_register_clock(CLOCK_REALTIME, &clock_realtime);
343         posix_timers_register_clock(CLOCK_MONOTONIC, &clock_monotonic);
344         posix_timers_register_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
345         posix_timers_register_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
346         posix_timers_register_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
347         posix_timers_register_clock(CLOCK_BOOTTIME, &clock_boottime);
348         posix_timers_register_clock(CLOCK_TAI, &clock_tai);
349 
350         posix_timers_cache = kmem_cache_create("posix_timers_cache",
351                                         sizeof (struct k_itimer), 0, SLAB_PANIC,
352                                         NULL);
353         return 0;
354 }
355 
356 __initcall(init_posix_timers);
357 
358 static void schedule_next_timer(struct k_itimer *timr)
359 {
360         struct hrtimer *timer = &timr->it.real.timer;
361 
362         if (timr->it.real.interval.tv64 == 0)
363                 return;
364 
365         timr->it_overrun += (unsigned int) hrtimer_forward(timer,
366                                                 timer->base->get_time(),
367                                                 timr->it.real.interval);
368 
369         timr->it_overrun_last = timr->it_overrun;
370         timr->it_overrun = -1;
371         ++timr->it_requeue_pending;
372         hrtimer_restart(timer);
373 }
374 
375 /*
376  * This function is exported for use by the signal deliver code.  It is
377  * called just prior to the info block being released and passes that
378  * block to us.  It's function is to update the overrun entry AND to
379  * restart the timer.  It should only be called if the timer is to be
380  * restarted (i.e. we have flagged this in the sys_private entry of the
381  * info block).
382  *
383  * To protect against the timer going away while the interrupt is queued,
384  * we require that the it_requeue_pending flag be set.
385  */
386 void do_schedule_next_timer(struct siginfo *info)
387 {
388         struct k_itimer *timr;
389         unsigned long flags;
390 
391         timr = lock_timer(info->si_tid, &flags);
392 
393         if (timr && timr->it_requeue_pending == info->si_sys_private) {
394                 if (timr->it_clock < 0)
395                         posix_cpu_timer_schedule(timr);
396                 else
397                         schedule_next_timer(timr);
398 
399                 info->si_overrun += timr->it_overrun_last;
400         }
401 
402         if (timr)
403                 unlock_timer(timr, flags);
404 }
405 
406 int posix_timer_event(struct k_itimer *timr, int si_private)
407 {
408         struct task_struct *task;
409         int shared, ret = -1;
410         /*
411          * FIXME: if ->sigq is queued we can race with
412          * dequeue_signal()->do_schedule_next_timer().
413          *
414          * If dequeue_signal() sees the "right" value of
415          * si_sys_private it calls do_schedule_next_timer().
416          * We re-queue ->sigq and drop ->it_lock().
417          * do_schedule_next_timer() locks the timer
418          * and re-schedules it while ->sigq is pending.
419          * Not really bad, but not that we want.
420          */
421         timr->sigq->info.si_sys_private = si_private;
422 
423         rcu_read_lock();
424         task = pid_task(timr->it_pid, PIDTYPE_PID);
425         if (task) {
426                 shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
427                 ret = send_sigqueue(timr->sigq, task, shared);
428         }
429         rcu_read_unlock();
430         /* If we failed to send the signal the timer stops. */
431         return ret > 0;
432 }
433 EXPORT_SYMBOL_GPL(posix_timer_event);
434 
435 /*
436  * This function gets called when a POSIX.1b interval timer expires.  It
437  * is used as a callback from the kernel internal timer.  The
438  * run_timer_list code ALWAYS calls with interrupts on.
439 
440  * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
441  */
442 static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
443 {
444         struct k_itimer *timr;
445         unsigned long flags;
446         int si_private = 0;
447         enum hrtimer_restart ret = HRTIMER_NORESTART;
448 
449         timr = container_of(timer, struct k_itimer, it.real.timer);
450         spin_lock_irqsave(&timr->it_lock, flags);
451 
452         if (timr->it.real.interval.tv64 != 0)
453                 si_private = ++timr->it_requeue_pending;
454 
455         if (posix_timer_event(timr, si_private)) {
456                 /*
457                  * signal was not sent because of sig_ignor
458                  * we will not get a call back to restart it AND
459                  * it should be restarted.
460                  */
461                 if (timr->it.real.interval.tv64 != 0) {
462                         ktime_t now = hrtimer_cb_get_time(timer);
463 
464                         /*
465                          * FIXME: What we really want, is to stop this
466                          * timer completely and restart it in case the
467                          * SIG_IGN is removed. This is a non trivial
468                          * change which involves sighand locking
469                          * (sigh !), which we don't want to do late in
470                          * the release cycle.
471                          *
472                          * For now we just let timers with an interval
473                          * less than a jiffie expire every jiffie to
474                          * avoid softirq starvation in case of SIG_IGN
475                          * and a very small interval, which would put
476                          * the timer right back on the softirq pending
477                          * list. By moving now ahead of time we trick
478                          * hrtimer_forward() to expire the timer
479                          * later, while we still maintain the overrun
480                          * accuracy, but have some inconsistency in
481                          * the timer_gettime() case. This is at least
482                          * better than a starved softirq. A more
483                          * complex fix which solves also another related
484                          * inconsistency is already in the pipeline.
485                          */
486 #ifdef CONFIG_HIGH_RES_TIMERS
487                         {
488                                 ktime_t kj = ktime_set(0, NSEC_PER_SEC / HZ);
489 
490                                 if (timr->it.real.interval.tv64 < kj.tv64)
491                                         now = ktime_add(now, kj);
492                         }
493 #endif
494                         timr->it_overrun += (unsigned int)
495                                 hrtimer_forward(timer, now,
496                                                 timr->it.real.interval);
497                         ret = HRTIMER_RESTART;
498                         ++timr->it_requeue_pending;
499                 }
500         }
501 
502         unlock_timer(timr, flags);
503         return ret;
504 }
505 
506 static struct pid *good_sigevent(sigevent_t * event)
507 {
508         struct task_struct *rtn = current->group_leader;
509 
510         if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
511                 (!(rtn = find_task_by_vpid(event->sigev_notify_thread_id)) ||
512                  !same_thread_group(rtn, current) ||
513                  (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
514                 return NULL;
515 
516         if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
517             ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
518                 return NULL;
519 
520         return task_pid(rtn);
521 }
522 
523 void posix_timers_register_clock(const clockid_t clock_id,
524                                  struct k_clock *new_clock)
525 {
526         if ((unsigned) clock_id >= MAX_CLOCKS) {
527                 printk(KERN_WARNING "POSIX clock register failed for clock_id %d\n",
528                        clock_id);
529                 return;
530         }
531 
532         if (!new_clock->clock_get) {
533                 printk(KERN_WARNING "POSIX clock id %d lacks clock_get()\n",
534                        clock_id);
535                 return;
536         }
537         if (!new_clock->clock_getres) {
538                 printk(KERN_WARNING "POSIX clock id %d lacks clock_getres()\n",
539                        clock_id);
540                 return;
541         }
542 
543         posix_clocks[clock_id] = *new_clock;
544 }
545 EXPORT_SYMBOL_GPL(posix_timers_register_clock);
546 
547 static struct k_itimer * alloc_posix_timer(void)
548 {
549         struct k_itimer *tmr;
550         tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
551         if (!tmr)
552                 return tmr;
553         if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
554                 kmem_cache_free(posix_timers_cache, tmr);
555                 return NULL;
556         }
557         memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
558         return tmr;
559 }
560 
561 static void k_itimer_rcu_free(struct rcu_head *head)
562 {
563         struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu);
564 
565         kmem_cache_free(posix_timers_cache, tmr);
566 }
567 
568 #define IT_ID_SET       1
569 #define IT_ID_NOT_SET   0
570 static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
571 {
572         if (it_id_set) {
573                 unsigned long flags;
574                 spin_lock_irqsave(&hash_lock, flags);
575                 hlist_del_rcu(&tmr->t_hash);
576                 spin_unlock_irqrestore(&hash_lock, flags);
577         }
578         put_pid(tmr->it_pid);
579         sigqueue_free(tmr->sigq);
580         call_rcu(&tmr->it.rcu, k_itimer_rcu_free);
581 }
582 
583 static struct k_clock *clockid_to_kclock(const clockid_t id)
584 {
585         if (id < 0)
586                 return (id & CLOCKFD_MASK) == CLOCKFD ?
587                         &clock_posix_dynamic : &clock_posix_cpu;
588 
589         if (id >= MAX_CLOCKS || !posix_clocks[id].clock_getres)
590                 return NULL;
591         return &posix_clocks[id];
592 }
593 
594 static int common_timer_create(struct k_itimer *new_timer)
595 {
596         hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
597         return 0;
598 }
599 
600 /* Create a POSIX.1b interval timer. */
601 
602 SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
603                 struct sigevent __user *, timer_event_spec,
604                 timer_t __user *, created_timer_id)
605 {
606         struct k_clock *kc = clockid_to_kclock(which_clock);
607         struct k_itimer *new_timer;
608         int error, new_timer_id;
609         sigevent_t event;
610         int it_id_set = IT_ID_NOT_SET;
611 
612         if (!kc)
613                 return -EINVAL;
614         if (!kc->timer_create)
615                 return -EOPNOTSUPP;
616 
617         new_timer = alloc_posix_timer();
618         if (unlikely(!new_timer))
619                 return -EAGAIN;
620 
621         spin_lock_init(&new_timer->it_lock);
622         new_timer_id = posix_timer_add(new_timer);
623         if (new_timer_id < 0) {
624                 error = new_timer_id;
625                 goto out;
626         }
627 
628         it_id_set = IT_ID_SET;
629         new_timer->it_id = (timer_t) new_timer_id;
630         new_timer->it_clock = which_clock;
631         new_timer->it_overrun = -1;
632 
633         if (timer_event_spec) {
634                 if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
635                         error = -EFAULT;
636                         goto out;
637                 }
638                 rcu_read_lock();
639                 new_timer->it_pid = get_pid(good_sigevent(&event));
640                 rcu_read_unlock();
641                 if (!new_timer->it_pid) {
642                         error = -EINVAL;
643                         goto out;
644                 }
645         } else {
646                 memset(&event.sigev_value, 0, sizeof(event.sigev_value));
647                 event.sigev_notify = SIGEV_SIGNAL;
648                 event.sigev_signo = SIGALRM;
649                 event.sigev_value.sival_int = new_timer->it_id;
650                 new_timer->it_pid = get_pid(task_tgid(current));
651         }
652 
653         new_timer->it_sigev_notify     = event.sigev_notify;
654         new_timer->sigq->info.si_signo = event.sigev_signo;
655         new_timer->sigq->info.si_value = event.sigev_value;
656         new_timer->sigq->info.si_tid   = new_timer->it_id;
657         new_timer->sigq->info.si_code  = SI_TIMER;
658 
659         if (copy_to_user(created_timer_id,
660                          &new_timer_id, sizeof (new_timer_id))) {
661                 error = -EFAULT;
662                 goto out;
663         }
664 
665         error = kc->timer_create(new_timer);
666         if (error)
667                 goto out;
668 
669         spin_lock_irq(&current->sighand->siglock);
670         new_timer->it_signal = current->signal;
671         list_add(&new_timer->list, &current->signal->posix_timers);
672         spin_unlock_irq(&current->sighand->siglock);
673 
674         return 0;
675         /*
676          * In the case of the timer belonging to another task, after
677          * the task is unlocked, the timer is owned by the other task
678          * and may cease to exist at any time.  Don't use or modify
679          * new_timer after the unlock call.
680          */
681 out:
682         release_posix_timer(new_timer, it_id_set);
683         return error;
684 }
685 
686 /*
687  * Locking issues: We need to protect the result of the id look up until
688  * we get the timer locked down so it is not deleted under us.  The
689  * removal is done under the idr spinlock so we use that here to bridge
690  * the find to the timer lock.  To avoid a dead lock, the timer id MUST
691  * be release with out holding the timer lock.
692  */
693 static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
694 {
695         struct k_itimer *timr;
696 
697         /*
698          * timer_t could be any type >= int and we want to make sure any
699          * @timer_id outside positive int range fails lookup.
700          */
701         if ((unsigned long long)timer_id > INT_MAX)
702                 return NULL;
703 
704         rcu_read_lock();
705         timr = posix_timer_by_id(timer_id);
706         if (timr) {
707                 spin_lock_irqsave(&timr->it_lock, *flags);
708                 if (timr->it_signal == current->signal) {
709                         rcu_read_unlock();
710                         return timr;
711                 }
712                 spin_unlock_irqrestore(&timr->it_lock, *flags);
713         }
714         rcu_read_unlock();
715 
716         return NULL;
717 }
718 
719 /*
720  * Get the time remaining on a POSIX.1b interval timer.  This function
721  * is ALWAYS called with spin_lock_irq on the timer, thus it must not
722  * mess with irq.
723  *
724  * We have a couple of messes to clean up here.  First there is the case
725  * of a timer that has a requeue pending.  These timers should appear to
726  * be in the timer list with an expiry as if we were to requeue them
727  * now.
728  *
729  * The second issue is the SIGEV_NONE timer which may be active but is
730  * not really ever put in the timer list (to save system resources).
731  * This timer may be expired, and if so, we will do it here.  Otherwise
732  * it is the same as a requeue pending timer WRT to what we should
733  * report.
734  */
735 static void
736 common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
737 {
738         ktime_t now, remaining, iv;
739         struct hrtimer *timer = &timr->it.real.timer;
740 
741         memset(cur_setting, 0, sizeof(struct itimerspec));
742 
743         iv = timr->it.real.interval;
744 
745         /* interval timer ? */
746         if (iv.tv64)
747                 cur_setting->it_interval = ktime_to_timespec(iv);
748         else if (!hrtimer_active(timer) &&
749                  (timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
750                 return;
751 
752         now = timer->base->get_time();
753 
754         /*
755          * When a requeue is pending or this is a SIGEV_NONE
756          * timer move the expiry time forward by intervals, so
757          * expiry is > now.
758          */
759         if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
760             (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
761                 timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
762 
763         remaining = ktime_sub(hrtimer_get_expires(timer), now);
764         /* Return 0 only, when the timer is expired and not pending */
765         if (remaining.tv64 <= 0) {
766                 /*
767                  * A single shot SIGEV_NONE timer must return 0, when
768                  * it is expired !
769                  */
770                 if ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
771                         cur_setting->it_value.tv_nsec = 1;
772         } else
773                 cur_setting->it_value = ktime_to_timespec(remaining);
774 }
775 
776 /* Get the time remaining on a POSIX.1b interval timer. */
777 SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
778                 struct itimerspec __user *, setting)
779 {
780         struct itimerspec cur_setting;
781         struct k_itimer *timr;
782         struct k_clock *kc;
783         unsigned long flags;
784         int ret = 0;
785 
786         timr = lock_timer(timer_id, &flags);
787         if (!timr)
788                 return -EINVAL;
789 
790         kc = clockid_to_kclock(timr->it_clock);
791         if (WARN_ON_ONCE(!kc || !kc->timer_get))
792                 ret = -EINVAL;
793         else
794                 kc->timer_get(timr, &cur_setting);
795 
796         unlock_timer(timr, flags);
797 
798         if (!ret && copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
799                 return -EFAULT;
800 
801         return ret;
802 }
803 
804 /*
805  * Get the number of overruns of a POSIX.1b interval timer.  This is to
806  * be the overrun of the timer last delivered.  At the same time we are
807  * accumulating overruns on the next timer.  The overrun is frozen when
808  * the signal is delivered, either at the notify time (if the info block
809  * is not queued) or at the actual delivery time (as we are informed by
810  * the call back to do_schedule_next_timer().  So all we need to do is
811  * to pick up the frozen overrun.
812  */
813 SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
814 {
815         struct k_itimer *timr;
816         int overrun;
817         unsigned long flags;
818 
819         timr = lock_timer(timer_id, &flags);
820         if (!timr)
821                 return -EINVAL;
822 
823         overrun = timr->it_overrun_last;
824         unlock_timer(timr, flags);
825 
826         return overrun;
827 }
828 
829 /* Set a POSIX.1b interval timer. */
830 /* timr->it_lock is taken. */
831 static int
832 common_timer_set(struct k_itimer *timr, int flags,
833                  struct itimerspec *new_setting, struct itimerspec *old_setting)
834 {
835         struct hrtimer *timer = &timr->it.real.timer;
836         enum hrtimer_mode mode;
837 
838         if (old_setting)
839                 common_timer_get(timr, old_setting);
840 
841         /* disable the timer */
842         timr->it.real.interval.tv64 = 0;
843         /*
844          * careful here.  If smp we could be in the "fire" routine which will
845          * be spinning as we hold the lock.  But this is ONLY an SMP issue.
846          */
847         if (hrtimer_try_to_cancel(timer) < 0)
848                 return TIMER_RETRY;
849 
850         timr->it_requeue_pending = (timr->it_requeue_pending + 2) & 
851                 ~REQUEUE_PENDING;
852         timr->it_overrun_last = 0;
853 
854         /* switch off the timer when it_value is zero */
855         if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
856                 return 0;
857 
858         mode = flags & TIMER_ABSTIME ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
859         hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
860         timr->it.real.timer.function = posix_timer_fn;
861 
862         hrtimer_set_expires(timer, timespec_to_ktime(new_setting->it_value));
863 
864         /* Convert interval */
865         timr->it.real.interval = timespec_to_ktime(new_setting->it_interval);
866 
867         /* SIGEV_NONE timers are not queued ! See common_timer_get */
868         if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
869                 /* Setup correct expiry time for relative timers */
870                 if (mode == HRTIMER_MODE_REL) {
871                         hrtimer_add_expires(timer, timer->base->get_time());
872                 }
873                 return 0;
874         }
875 
876         hrtimer_start_expires(timer, mode);
877         return 0;
878 }
879 
880 /* Set a POSIX.1b interval timer */
881 SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
882                 const struct itimerspec __user *, new_setting,
883                 struct itimerspec __user *, old_setting)
884 {
885         struct k_itimer *timr;
886         struct itimerspec new_spec, old_spec;
887         int error = 0;
888         unsigned long flag;
889         struct itimerspec *rtn = old_setting ? &old_spec : NULL;
890         struct k_clock *kc;
891 
892         if (!new_setting)
893                 return -EINVAL;
894 
895         if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
896                 return -EFAULT;
897 
898         if (!timespec_valid(&new_spec.it_interval) ||
899             !timespec_valid(&new_spec.it_value))
900                 return -EINVAL;
901 retry:
902         timr = lock_timer(timer_id, &flag);
903         if (!timr)
904                 return -EINVAL;
905 
906         kc = clockid_to_kclock(timr->it_clock);
907         if (WARN_ON_ONCE(!kc || !kc->timer_set))
908                 error = -EINVAL;
909         else
910                 error = kc->timer_set(timr, flags, &new_spec, rtn);
911 
912         unlock_timer(timr, flag);
913         if (error == TIMER_RETRY) {
914                 rtn = NULL;     // We already got the old time...
915                 goto retry;
916         }
917 
918         if (old_setting && !error &&
919             copy_to_user(old_setting, &old_spec, sizeof (old_spec)))
920                 error = -EFAULT;
921 
922         return error;
923 }
924 
925 static int common_timer_del(struct k_itimer *timer)
926 {
927         timer->it.real.interval.tv64 = 0;
928 
929         if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0)
930                 return TIMER_RETRY;
931         return 0;
932 }
933 
934 static inline int timer_delete_hook(struct k_itimer *timer)
935 {
936         struct k_clock *kc = clockid_to_kclock(timer->it_clock);
937 
938         if (WARN_ON_ONCE(!kc || !kc->timer_del))
939                 return -EINVAL;
940         return kc->timer_del(timer);
941 }
942 
943 /* Delete a POSIX.1b interval timer. */
944 SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
945 {
946         struct k_itimer *timer;
947         unsigned long flags;
948 
949 retry_delete:
950         timer = lock_timer(timer_id, &flags);
951         if (!timer)
952                 return -EINVAL;
953 
954         if (timer_delete_hook(timer) == TIMER_RETRY) {
955                 unlock_timer(timer, flags);
956                 goto retry_delete;
957         }
958 
959         spin_lock(&current->sighand->siglock);
960         list_del(&timer->list);
961         spin_unlock(&current->sighand->siglock);
962         /*
963          * This keeps any tasks waiting on the spin lock from thinking
964          * they got something (see the lock code above).
965          */
966         timer->it_signal = NULL;
967 
968         unlock_timer(timer, flags);
969         release_posix_timer(timer, IT_ID_SET);
970         return 0;
971 }
972 
973 /*
974  * return timer owned by the process, used by exit_itimers
975  */
976 static void itimer_delete(struct k_itimer *timer)
977 {
978         unsigned long flags;
979 
980 retry_delete:
981         spin_lock_irqsave(&timer->it_lock, flags);
982 
983         if (timer_delete_hook(timer) == TIMER_RETRY) {
984                 unlock_timer(timer, flags);
985                 goto retry_delete;
986         }
987         list_del(&timer->list);
988         /*
989          * This keeps any tasks waiting on the spin lock from thinking
990          * they got something (see the lock code above).
991          */
992         timer->it_signal = NULL;
993 
994         unlock_timer(timer, flags);
995         release_posix_timer(timer, IT_ID_SET);
996 }
997 
998 /*
999  * This is called by do_exit or de_thread, only when there are no more
1000  * references to the shared signal_struct.
1001  */
1002 void exit_itimers(struct signal_struct *sig)
1003 {
1004         struct k_itimer *tmr;
1005 
1006         while (!list_empty(&sig->posix_timers)) {
1007                 tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
1008                 itimer_delete(tmr);
1009         }
1010 }
1011 
1012 SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
1013                 const struct timespec __user *, tp)
1014 {
1015         struct k_clock *kc = clockid_to_kclock(which_clock);
1016         struct timespec new_tp;
1017 
1018         if (!kc || !kc->clock_set)
1019                 return -EINVAL;
1020 
1021         if (copy_from_user(&new_tp, tp, sizeof (*tp)))
1022                 return -EFAULT;
1023 
1024         return kc->clock_set(which_clock, &new_tp);
1025 }
1026 
1027 SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
1028                 struct timespec __user *,tp)
1029 {
1030         struct k_clock *kc = clockid_to_kclock(which_clock);
1031         struct timespec kernel_tp;
1032         int error;
1033 
1034         if (!kc)
1035                 return -EINVAL;
1036 
1037         error = kc->clock_get(which_clock, &kernel_tp);
1038 
1039         if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
1040                 error = -EFAULT;
1041 
1042         return error;
1043 }
1044 
1045 SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
1046                 struct timex __user *, utx)
1047 {
1048         struct k_clock *kc = clockid_to_kclock(which_clock);
1049         struct timex ktx;
1050         int err;
1051 
1052         if (!kc)
1053                 return -EINVAL;
1054         if (!kc->clock_adj)
1055                 return -EOPNOTSUPP;
1056 
1057         if (copy_from_user(&ktx, utx, sizeof(ktx)))
1058                 return -EFAULT;
1059 
1060         err = kc->clock_adj(which_clock, &ktx);
1061 
1062         if (err >= 0 && copy_to_user(utx, &ktx, sizeof(ktx)))
1063                 return -EFAULT;
1064 
1065         return err;
1066 }
1067 
1068 SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
1069                 struct timespec __user *, tp)
1070 {
1071         struct k_clock *kc = clockid_to_kclock(which_clock);
1072         struct timespec rtn_tp;
1073         int error;
1074 
1075         if (!kc)
1076                 return -EINVAL;
1077 
1078         error = kc->clock_getres(which_clock, &rtn_tp);
1079 
1080         if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp)))
1081                 error = -EFAULT;
1082 
1083         return error;
1084 }
1085 
1086 /*
1087  * nanosleep for monotonic and realtime clocks
1088  */
1089 static int common_nsleep(const clockid_t which_clock, int flags,
1090                          struct timespec *tsave, struct timespec __user *rmtp)
1091 {
1092         return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
1093                                  HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
1094                                  which_clock);
1095 }
1096 
1097 SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
1098                 const struct timespec __user *, rqtp,
1099                 struct timespec __user *, rmtp)
1100 {
1101         struct k_clock *kc = clockid_to_kclock(which_clock);
1102         struct timespec t;
1103 
1104         if (!kc)
1105                 return -EINVAL;
1106         if (!kc->nsleep)
1107                 return -ENANOSLEEP_NOTSUP;
1108 
1109         if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
1110                 return -EFAULT;
1111 
1112         if (!timespec_valid(&t))
1113                 return -EINVAL;
1114 
1115         return kc->nsleep(which_clock, flags, &t, rmtp);
1116 }
1117 
1118 /*
1119  * This will restart clock_nanosleep. This is required only by
1120  * compat_clock_nanosleep_restart for now.
1121  */
1122 long clock_nanosleep_restart(struct restart_block *restart_block)
1123 {
1124         clockid_t which_clock = restart_block->nanosleep.clockid;
1125         struct k_clock *kc = clockid_to_kclock(which_clock);
1126 
1127         if (WARN_ON_ONCE(!kc || !kc->nsleep_restart))
1128                 return -EINVAL;
1129 
1130         return kc->nsleep_restart(restart_block);
1131 }
1132 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp