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

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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/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 /*
 53  * Management arrays for POSIX timers. Timers are now kept in static hash table
 54  * with 512 entries.
 55  * Timer ids are allocated by local routine, which selects proper hash head by
 56  * key, constructed from current->signal address and per signal struct counter.
 57  * This keeps timer ids unique per process, but now they can intersect between
 58  * processes.
 59  */
 60 
 61 /*
 62  * Lets keep our timers in a slab cache :-)
 63  */
 64 static struct kmem_cache *posix_timers_cache;
 65 
 66 static DEFINE_HASHTABLE(posix_timers_hashtable, 9);
 67 static DEFINE_SPINLOCK(hash_lock);
 68 
 69 /*
 70  * we assume that the new SIGEV_THREAD_ID shares no bits with the other
 71  * SIGEV values.  Here we put out an error if this assumption fails.
 72  */
 73 #if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
 74                        ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
 75 #error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
 76 #endif
 77 
 78 /*
 79  * parisc wants ENOTSUP instead of EOPNOTSUPP
 80  */
 81 #ifndef ENOTSUP
 82 # define ENANOSLEEP_NOTSUP EOPNOTSUPP
 83 #else
 84 # define ENANOSLEEP_NOTSUP ENOTSUP
 85 #endif
 86 
 87 /*
 88  * The timer ID is turned into a timer address by idr_find().
 89  * Verifying a valid ID consists of:
 90  *
 91  * a) checking that idr_find() returns other than -1.
 92  * b) checking that the timer id matches the one in the timer itself.
 93  * c) that the timer owner is in the callers thread group.
 94  */
 95 
 96 /*
 97  * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
 98  *          to implement others.  This structure defines the various
 99  *          clocks.
100  *
101  * RESOLUTION: Clock resolution is used to round up timer and interval
102  *          times, NOT to report clock times, which are reported with as
103  *          much resolution as the system can muster.  In some cases this
104  *          resolution may depend on the underlying clock hardware and
105  *          may not be quantifiable until run time, and only then is the
106  *          necessary code is written.  The standard says we should say
107  *          something about this issue in the documentation...
108  *
109  * FUNCTIONS: The CLOCKs structure defines possible functions to
110  *          handle various clock functions.
111  *
112  *          The standard POSIX timer management code assumes the
113  *          following: 1.) The k_itimer struct (sched.h) is used for
114  *          the timer.  2.) The list, it_lock, it_clock, it_id and
115  *          it_pid fields are not modified by timer code.
116  *
117  * Permissions: It is assumed that the clock_settime() function defined
118  *          for each clock will take care of permission checks.  Some
119  *          clocks may be set able by any user (i.e. local process
120  *          clocks) others not.  Currently the only set able clock we
121  *          have is CLOCK_REALTIME and its high res counter part, both of
122  *          which we beg off on and pass to do_sys_settimeofday().
123  */
124 
125 static struct k_clock posix_clocks[MAX_CLOCKS];
126 
127 /*
128  * These ones are defined below.
129  */
130 static int common_nsleep(const clockid_t, int flags, struct timespec *t,
131                          struct timespec __user *rmtp);
132 static int common_timer_create(struct k_itimer *new_timer);
133 static void common_timer_get(struct k_itimer *, struct itimerspec *);
134 static int common_timer_set(struct k_itimer *, int,
135                             struct itimerspec *, struct itimerspec *);
136 static int common_timer_del(struct k_itimer *timer);
137 
138 static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
139 
140 static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
141 
142 #define lock_timer(tid, flags)                                             \
143 ({      struct k_itimer *__timr;                                           \
144         __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags));  \
145         __timr;                                                            \
146 })
147 
148 static int hash(struct signal_struct *sig, unsigned int nr)
149 {
150         return hash_32(hash32_ptr(sig) ^ nr, HASH_BITS(posix_timers_hashtable));
151 }
152 
153 static struct k_itimer *__posix_timers_find(struct hlist_head *head,
154                                             struct signal_struct *sig,
155                                             timer_t id)
156 {
157         struct k_itimer *timer;
158 
159         hlist_for_each_entry_rcu(timer, head, t_hash) {
160                 if ((timer->it_signal == sig) && (timer->it_id == id))
161                         return timer;
162         }
163         return NULL;
164 }
165 
166 static struct k_itimer *posix_timer_by_id(timer_t id)
167 {
168         struct signal_struct *sig = current->signal;
169         struct hlist_head *head = &posix_timers_hashtable[hash(sig, id)];
170 
171         return __posix_timers_find(head, sig, id);
172 }
173 
174 static int posix_timer_add(struct k_itimer *timer)
175 {
176         struct signal_struct *sig = current->signal;
177         int first_free_id = sig->posix_timer_id;
178         struct hlist_head *head;
179         int ret = -ENOENT;
180 
181         do {
182                 spin_lock(&hash_lock);
183                 head = &posix_timers_hashtable[hash(sig, sig->posix_timer_id)];
184                 if (!__posix_timers_find(head, sig, sig->posix_timer_id)) {
185                         hlist_add_head_rcu(&timer->t_hash, head);
186                         ret = sig->posix_timer_id;
187                 }
188                 if (++sig->posix_timer_id < 0)
189                         sig->posix_timer_id = 0;
190                 if ((sig->posix_timer_id == first_free_id) && (ret == -ENOENT))
191                         /* Loop over all possible ids completed */
192                         ret = -EAGAIN;
193                 spin_unlock(&hash_lock);
194         } while (ret == -ENOENT);
195         return ret;
196 }
197 
198 static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
199 {
200         spin_unlock_irqrestore(&timr->it_lock, flags);
201 }
202 
203 /* Get clock_realtime */
204 static int posix_clock_realtime_get(clockid_t which_clock, struct timespec *tp)
205 {
206         ktime_get_real_ts(tp);
207         return 0;
208 }
209 
210 /* Set clock_realtime */
211 static int posix_clock_realtime_set(const clockid_t which_clock,
212                                     const struct timespec *tp)
213 {
214         return do_sys_settimeofday(tp, NULL);
215 }
216 
217 static int posix_clock_realtime_adj(const clockid_t which_clock,
218                                     struct timex *t)
219 {
220         return do_adjtimex(t);
221 }
222 
223 /*
224  * Get monotonic time for posix timers
225  */
226 static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
227 {
228         ktime_get_ts(tp);
229         return 0;
230 }
231 
232 /*
233  * Get monotonic-raw time for posix timers
234  */
235 static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
236 {
237         getrawmonotonic(tp);
238         return 0;
239 }
240 
241 
242 static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp)
243 {
244         *tp = current_kernel_time();
245         return 0;
246 }
247 
248 static int posix_get_monotonic_coarse(clockid_t which_clock,
249                                                 struct timespec *tp)
250 {
251         *tp = get_monotonic_coarse();
252         return 0;
253 }
254 
255 static int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp)
256 {
257         *tp = ktime_to_timespec(KTIME_LOW_RES);
258         return 0;
259 }
260 
261 static int posix_get_boottime(const clockid_t which_clock, struct timespec *tp)
262 {
263         get_monotonic_boottime(tp);
264         return 0;
265 }
266 
267 static int posix_get_tai(clockid_t which_clock, struct timespec *tp)
268 {
269         timekeeping_clocktai(tp);
270         return 0;
271 }
272 
273 /*
274  * Initialize everything, well, just everything in Posix clocks/timers ;)
275  */
276 static __init int init_posix_timers(void)
277 {
278         struct k_clock clock_realtime = {
279                 .clock_getres   = hrtimer_get_res,
280                 .clock_get      = posix_clock_realtime_get,
281                 .clock_set      = posix_clock_realtime_set,
282                 .clock_adj      = posix_clock_realtime_adj,
283                 .nsleep         = common_nsleep,
284                 .nsleep_restart = hrtimer_nanosleep_restart,
285                 .timer_create   = common_timer_create,
286                 .timer_set      = common_timer_set,
287                 .timer_get      = common_timer_get,
288                 .timer_del      = common_timer_del,
289         };
290         struct k_clock clock_monotonic = {
291                 .clock_getres   = hrtimer_get_res,
292                 .clock_get      = posix_ktime_get_ts,
293                 .nsleep         = common_nsleep,
294                 .nsleep_restart = hrtimer_nanosleep_restart,
295                 .timer_create   = common_timer_create,
296                 .timer_set      = common_timer_set,
297                 .timer_get      = common_timer_get,
298                 .timer_del      = common_timer_del,
299         };
300         struct k_clock clock_monotonic_raw = {
301                 .clock_getres   = hrtimer_get_res,
302                 .clock_get      = posix_get_monotonic_raw,
303         };
304         struct k_clock clock_realtime_coarse = {
305                 .clock_getres   = posix_get_coarse_res,
306                 .clock_get      = posix_get_realtime_coarse,
307         };
308         struct k_clock clock_monotonic_coarse = {
309                 .clock_getres   = posix_get_coarse_res,
310                 .clock_get      = posix_get_monotonic_coarse,
311         };
312         struct k_clock clock_tai = {
313                 .clock_getres   = hrtimer_get_res,
314                 .clock_get      = posix_get_tai,
315                 .nsleep         = common_nsleep,
316                 .nsleep_restart = hrtimer_nanosleep_restart,
317                 .timer_create   = common_timer_create,
318                 .timer_set      = common_timer_set,
319                 .timer_get      = common_timer_get,
320                 .timer_del      = common_timer_del,
321         };
322         struct k_clock clock_boottime = {
323                 .clock_getres   = hrtimer_get_res,
324                 .clock_get      = posix_get_boottime,
325                 .nsleep         = common_nsleep,
326                 .nsleep_restart = hrtimer_nanosleep_restart,
327                 .timer_create   = common_timer_create,
328                 .timer_set      = common_timer_set,
329                 .timer_get      = common_timer_get,
330                 .timer_del      = common_timer_del,
331         };
332 
333         posix_timers_register_clock(CLOCK_REALTIME, &clock_realtime);
334         posix_timers_register_clock(CLOCK_MONOTONIC, &clock_monotonic);
335         posix_timers_register_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
336         posix_timers_register_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
337         posix_timers_register_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
338         posix_timers_register_clock(CLOCK_BOOTTIME, &clock_boottime);
339         posix_timers_register_clock(CLOCK_TAI, &clock_tai);
340 
341         posix_timers_cache = kmem_cache_create("posix_timers_cache",
342                                         sizeof (struct k_itimer), 0, SLAB_PANIC,
343                                         NULL);
344         return 0;
345 }
346 
347 __initcall(init_posix_timers);
348 
349 static void schedule_next_timer(struct k_itimer *timr)
350 {
351         struct hrtimer *timer = &timr->it.real.timer;
352 
353         if (timr->it.real.interval.tv64 == 0)
354                 return;
355 
356         timr->it_overrun += (unsigned int) hrtimer_forward(timer,
357                                                 timer->base->get_time(),
358                                                 timr->it.real.interval);
359 
360         timr->it_overrun_last = timr->it_overrun;
361         timr->it_overrun = -1;
362         ++timr->it_requeue_pending;
363         hrtimer_restart(timer);
364 }
365 
366 /*
367  * This function is exported for use by the signal deliver code.  It is
368  * called just prior to the info block being released and passes that
369  * block to us.  It's function is to update the overrun entry AND to
370  * restart the timer.  It should only be called if the timer is to be
371  * restarted (i.e. we have flagged this in the sys_private entry of the
372  * info block).
373  *
374  * To protect against the timer going away while the interrupt is queued,
375  * we require that the it_requeue_pending flag be set.
376  */
377 void do_schedule_next_timer(struct siginfo *info)
378 {
379         struct k_itimer *timr;
380         unsigned long flags;
381 
382         timr = lock_timer(info->si_tid, &flags);
383 
384         if (timr && timr->it_requeue_pending == info->si_sys_private) {
385                 if (timr->it_clock < 0)
386                         posix_cpu_timer_schedule(timr);
387                 else
388                         schedule_next_timer(timr);
389 
390                 info->si_overrun += timr->it_overrun_last;
391         }
392 
393         if (timr)
394                 unlock_timer(timr, flags);
395 }
396 
397 int posix_timer_event(struct k_itimer *timr, int si_private)
398 {
399         struct task_struct *task;
400         int shared, ret = -1;
401         /*
402          * FIXME: if ->sigq is queued we can race with
403          * dequeue_signal()->do_schedule_next_timer().
404          *
405          * If dequeue_signal() sees the "right" value of
406          * si_sys_private it calls do_schedule_next_timer().
407          * We re-queue ->sigq and drop ->it_lock().
408          * do_schedule_next_timer() locks the timer
409          * and re-schedules it while ->sigq is pending.
410          * Not really bad, but not that we want.
411          */
412         timr->sigq->info.si_sys_private = si_private;
413 
414         rcu_read_lock();
415         task = pid_task(timr->it_pid, PIDTYPE_PID);
416         if (task) {
417                 shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
418                 ret = send_sigqueue(timr->sigq, task, shared);
419         }
420         rcu_read_unlock();
421         /* If we failed to send the signal the timer stops. */
422         return ret > 0;
423 }
424 EXPORT_SYMBOL_GPL(posix_timer_event);
425 
426 /*
427  * This function gets called when a POSIX.1b interval timer expires.  It
428  * is used as a callback from the kernel internal timer.  The
429  * run_timer_list code ALWAYS calls with interrupts on.
430 
431  * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
432  */
433 static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
434 {
435         struct k_itimer *timr;
436         unsigned long flags;
437         int si_private = 0;
438         enum hrtimer_restart ret = HRTIMER_NORESTART;
439 
440         timr = container_of(timer, struct k_itimer, it.real.timer);
441         spin_lock_irqsave(&timr->it_lock, flags);
442 
443         if (timr->it.real.interval.tv64 != 0)
444                 si_private = ++timr->it_requeue_pending;
445 
446         if (posix_timer_event(timr, si_private)) {
447                 /*
448                  * signal was not sent because of sig_ignor
449                  * we will not get a call back to restart it AND
450                  * it should be restarted.
451                  */
452                 if (timr->it.real.interval.tv64 != 0) {
453                         ktime_t now = hrtimer_cb_get_time(timer);
454 
455                         /*
456                          * FIXME: What we really want, is to stop this
457                          * timer completely and restart it in case the
458                          * SIG_IGN is removed. This is a non trivial
459                          * change which involves sighand locking
460                          * (sigh !), which we don't want to do late in
461                          * the release cycle.
462                          *
463                          * For now we just let timers with an interval
464                          * less than a jiffie expire every jiffie to
465                          * avoid softirq starvation in case of SIG_IGN
466                          * and a very small interval, which would put
467                          * the timer right back on the softirq pending
468                          * list. By moving now ahead of time we trick
469                          * hrtimer_forward() to expire the timer
470                          * later, while we still maintain the overrun
471                          * accuracy, but have some inconsistency in
472                          * the timer_gettime() case. This is at least
473                          * better than a starved softirq. A more
474                          * complex fix which solves also another related
475                          * inconsistency is already in the pipeline.
476                          */
477 #ifdef CONFIG_HIGH_RES_TIMERS
478                         {
479                                 ktime_t kj = ktime_set(0, NSEC_PER_SEC / HZ);
480 
481                                 if (timr->it.real.interval.tv64 < kj.tv64)
482                                         now = ktime_add(now, kj);
483                         }
484 #endif
485                         timr->it_overrun += (unsigned int)
486                                 hrtimer_forward(timer, now,
487                                                 timr->it.real.interval);
488                         ret = HRTIMER_RESTART;
489                         ++timr->it_requeue_pending;
490                 }
491         }
492 
493         unlock_timer(timr, flags);
494         return ret;
495 }
496 
497 static struct pid *good_sigevent(sigevent_t * event)
498 {
499         struct task_struct *rtn = current->group_leader;
500 
501         if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
502                 (!(rtn = find_task_by_vpid(event->sigev_notify_thread_id)) ||
503                  !same_thread_group(rtn, current) ||
504                  (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
505                 return NULL;
506 
507         if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
508             ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
509                 return NULL;
510 
511         return task_pid(rtn);
512 }
513 
514 void posix_timers_register_clock(const clockid_t clock_id,
515                                  struct k_clock *new_clock)
516 {
517         if ((unsigned) clock_id >= MAX_CLOCKS) {
518                 printk(KERN_WARNING "POSIX clock register failed for clock_id %d\n",
519                        clock_id);
520                 return;
521         }
522 
523         if (!new_clock->clock_get) {
524                 printk(KERN_WARNING "POSIX clock id %d lacks clock_get()\n",
525                        clock_id);
526                 return;
527         }
528         if (!new_clock->clock_getres) {
529                 printk(KERN_WARNING "POSIX clock id %d lacks clock_getres()\n",
530                        clock_id);
531                 return;
532         }
533 
534         posix_clocks[clock_id] = *new_clock;
535 }
536 EXPORT_SYMBOL_GPL(posix_timers_register_clock);
537 
538 static struct k_itimer * alloc_posix_timer(void)
539 {
540         struct k_itimer *tmr;
541         tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
542         if (!tmr)
543                 return tmr;
544         if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
545                 kmem_cache_free(posix_timers_cache, tmr);
546                 return NULL;
547         }
548         memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
549         return tmr;
550 }
551 
552 static void k_itimer_rcu_free(struct rcu_head *head)
553 {
554         struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu);
555 
556         kmem_cache_free(posix_timers_cache, tmr);
557 }
558 
559 #define IT_ID_SET       1
560 #define IT_ID_NOT_SET   0
561 static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
562 {
563         if (it_id_set) {
564                 unsigned long flags;
565                 spin_lock_irqsave(&hash_lock, flags);
566                 hlist_del_rcu(&tmr->t_hash);
567                 spin_unlock_irqrestore(&hash_lock, flags);
568         }
569         put_pid(tmr->it_pid);
570         sigqueue_free(tmr->sigq);
571         call_rcu(&tmr->it.rcu, k_itimer_rcu_free);
572 }
573 
574 static struct k_clock *clockid_to_kclock(const clockid_t id)
575 {
576         if (id < 0)
577                 return (id & CLOCKFD_MASK) == CLOCKFD ?
578                         &clock_posix_dynamic : &clock_posix_cpu;
579 
580         if (id >= MAX_CLOCKS || !posix_clocks[id].clock_getres)
581                 return NULL;
582         return &posix_clocks[id];
583 }
584 
585 static int common_timer_create(struct k_itimer *new_timer)
586 {
587         hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
588         return 0;
589 }
590 
591 /* Create a POSIX.1b interval timer. */
592 
593 SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
594                 struct sigevent __user *, timer_event_spec,
595                 timer_t __user *, created_timer_id)
596 {
597         struct k_clock *kc = clockid_to_kclock(which_clock);
598         struct k_itimer *new_timer;
599         int error, new_timer_id;
600         sigevent_t event;
601         int it_id_set = IT_ID_NOT_SET;
602 
603         if (!kc)
604                 return -EINVAL;
605         if (!kc->timer_create)
606                 return -EOPNOTSUPP;
607 
608         new_timer = alloc_posix_timer();
609         if (unlikely(!new_timer))
610                 return -EAGAIN;
611 
612         spin_lock_init(&new_timer->it_lock);
613         new_timer_id = posix_timer_add(new_timer);
614         if (new_timer_id < 0) {
615                 error = new_timer_id;
616                 goto out;
617         }
618 
619         it_id_set = IT_ID_SET;
620         new_timer->it_id = (timer_t) new_timer_id;
621         new_timer->it_clock = which_clock;
622         new_timer->it_overrun = -1;
623 
624         if (timer_event_spec) {
625                 if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
626                         error = -EFAULT;
627                         goto out;
628                 }
629                 rcu_read_lock();
630                 new_timer->it_pid = get_pid(good_sigevent(&event));
631                 rcu_read_unlock();
632                 if (!new_timer->it_pid) {
633                         error = -EINVAL;
634                         goto out;
635                 }
636         } else {
637                 event.sigev_notify = SIGEV_SIGNAL;
638                 event.sigev_signo = SIGALRM;
639                 event.sigev_value.sival_int = new_timer->it_id;
640                 new_timer->it_pid = get_pid(task_tgid(current));
641         }
642 
643         new_timer->it_sigev_notify     = event.sigev_notify;
644         new_timer->sigq->info.si_signo = event.sigev_signo;
645         new_timer->sigq->info.si_value = event.sigev_value;
646         new_timer->sigq->info.si_tid   = new_timer->it_id;
647         new_timer->sigq->info.si_code  = SI_TIMER;
648 
649         if (copy_to_user(created_timer_id,
650                          &new_timer_id, sizeof (new_timer_id))) {
651                 error = -EFAULT;
652                 goto out;
653         }
654 
655         error = kc->timer_create(new_timer);
656         if (error)
657                 goto out;
658 
659         spin_lock_irq(&current->sighand->siglock);
660         new_timer->it_signal = current->signal;
661         list_add(&new_timer->list, &current->signal->posix_timers);
662         spin_unlock_irq(&current->sighand->siglock);
663 
664         return 0;
665         /*
666          * In the case of the timer belonging to another task, after
667          * the task is unlocked, the timer is owned by the other task
668          * and may cease to exist at any time.  Don't use or modify
669          * new_timer after the unlock call.
670          */
671 out:
672         release_posix_timer(new_timer, it_id_set);
673         return error;
674 }
675 
676 /*
677  * Locking issues: We need to protect the result of the id look up until
678  * we get the timer locked down so it is not deleted under us.  The
679  * removal is done under the idr spinlock so we use that here to bridge
680  * the find to the timer lock.  To avoid a dead lock, the timer id MUST
681  * be release with out holding the timer lock.
682  */
683 static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
684 {
685         struct k_itimer *timr;
686 
687         /*
688          * timer_t could be any type >= int and we want to make sure any
689          * @timer_id outside positive int range fails lookup.
690          */
691         if ((unsigned long long)timer_id > INT_MAX)
692                 return NULL;
693 
694         rcu_read_lock();
695         timr = posix_timer_by_id(timer_id);
696         if (timr) {
697                 spin_lock_irqsave(&timr->it_lock, *flags);
698                 if (timr->it_signal == current->signal) {
699                         rcu_read_unlock();
700                         return timr;
701                 }
702                 spin_unlock_irqrestore(&timr->it_lock, *flags);
703         }
704         rcu_read_unlock();
705 
706         return NULL;
707 }
708 
709 /*
710  * Get the time remaining on a POSIX.1b interval timer.  This function
711  * is ALWAYS called with spin_lock_irq on the timer, thus it must not
712  * mess with irq.
713  *
714  * We have a couple of messes to clean up here.  First there is the case
715  * of a timer that has a requeue pending.  These timers should appear to
716  * be in the timer list with an expiry as if we were to requeue them
717  * now.
718  *
719  * The second issue is the SIGEV_NONE timer which may be active but is
720  * not really ever put in the timer list (to save system resources).
721  * This timer may be expired, and if so, we will do it here.  Otherwise
722  * it is the same as a requeue pending timer WRT to what we should
723  * report.
724  */
725 static void
726 common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
727 {
728         ktime_t now, remaining, iv;
729         struct hrtimer *timer = &timr->it.real.timer;
730 
731         memset(cur_setting, 0, sizeof(struct itimerspec));
732 
733         iv = timr->it.real.interval;
734 
735         /* interval timer ? */
736         if (iv.tv64)
737                 cur_setting->it_interval = ktime_to_timespec(iv);
738         else if (!hrtimer_active(timer) &&
739                  (timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
740                 return;
741 
742         now = timer->base->get_time();
743 
744         /*
745          * When a requeue is pending or this is a SIGEV_NONE
746          * timer move the expiry time forward by intervals, so
747          * expiry is > now.
748          */
749         if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
750             (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
751                 timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
752 
753         remaining = ktime_sub(hrtimer_get_expires(timer), now);
754         /* Return 0 only, when the timer is expired and not pending */
755         if (remaining.tv64 <= 0) {
756                 /*
757                  * A single shot SIGEV_NONE timer must return 0, when
758                  * it is expired !
759                  */
760                 if ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
761                         cur_setting->it_value.tv_nsec = 1;
762         } else
763                 cur_setting->it_value = ktime_to_timespec(remaining);
764 }
765 
766 /* Get the time remaining on a POSIX.1b interval timer. */
767 SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
768                 struct itimerspec __user *, setting)
769 {
770         struct itimerspec cur_setting;
771         struct k_itimer *timr;
772         struct k_clock *kc;
773         unsigned long flags;
774         int ret = 0;
775 
776         timr = lock_timer(timer_id, &flags);
777         if (!timr)
778                 return -EINVAL;
779 
780         kc = clockid_to_kclock(timr->it_clock);
781         if (WARN_ON_ONCE(!kc || !kc->timer_get))
782                 ret = -EINVAL;
783         else
784                 kc->timer_get(timr, &cur_setting);
785 
786         unlock_timer(timr, flags);
787 
788         if (!ret && copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
789                 return -EFAULT;
790 
791         return ret;
792 }
793 
794 /*
795  * Get the number of overruns of a POSIX.1b interval timer.  This is to
796  * be the overrun of the timer last delivered.  At the same time we are
797  * accumulating overruns on the next timer.  The overrun is frozen when
798  * the signal is delivered, either at the notify time (if the info block
799  * is not queued) or at the actual delivery time (as we are informed by
800  * the call back to do_schedule_next_timer().  So all we need to do is
801  * to pick up the frozen overrun.
802  */
803 SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
804 {
805         struct k_itimer *timr;
806         int overrun;
807         unsigned long flags;
808 
809         timr = lock_timer(timer_id, &flags);
810         if (!timr)
811                 return -EINVAL;
812 
813         overrun = timr->it_overrun_last;
814         unlock_timer(timr, flags);
815 
816         return overrun;
817 }
818 
819 /* Set a POSIX.1b interval timer. */
820 /* timr->it_lock is taken. */
821 static int
822 common_timer_set(struct k_itimer *timr, int flags,
823                  struct itimerspec *new_setting, struct itimerspec *old_setting)
824 {
825         struct hrtimer *timer = &timr->it.real.timer;
826         enum hrtimer_mode mode;
827 
828         if (old_setting)
829                 common_timer_get(timr, old_setting);
830 
831         /* disable the timer */
832         timr->it.real.interval.tv64 = 0;
833         /*
834          * careful here.  If smp we could be in the "fire" routine which will
835          * be spinning as we hold the lock.  But this is ONLY an SMP issue.
836          */
837         if (hrtimer_try_to_cancel(timer) < 0)
838                 return TIMER_RETRY;
839 
840         timr->it_requeue_pending = (timr->it_requeue_pending + 2) & 
841                 ~REQUEUE_PENDING;
842         timr->it_overrun_last = 0;
843 
844         /* switch off the timer when it_value is zero */
845         if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
846                 return 0;
847 
848         mode = flags & TIMER_ABSTIME ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
849         hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
850         timr->it.real.timer.function = posix_timer_fn;
851 
852         hrtimer_set_expires(timer, timespec_to_ktime(new_setting->it_value));
853 
854         /* Convert interval */
855         timr->it.real.interval = timespec_to_ktime(new_setting->it_interval);
856 
857         /* SIGEV_NONE timers are not queued ! See common_timer_get */
858         if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
859                 /* Setup correct expiry time for relative timers */
860                 if (mode == HRTIMER_MODE_REL) {
861                         hrtimer_add_expires(timer, timer->base->get_time());
862                 }
863                 return 0;
864         }
865 
866         hrtimer_start_expires(timer, mode);
867         return 0;
868 }
869 
870 /* Set a POSIX.1b interval timer */
871 SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
872                 const struct itimerspec __user *, new_setting,
873                 struct itimerspec __user *, old_setting)
874 {
875         struct k_itimer *timr;
876         struct itimerspec new_spec, old_spec;
877         int error = 0;
878         unsigned long flag;
879         struct itimerspec *rtn = old_setting ? &old_spec : NULL;
880         struct k_clock *kc;
881 
882         if (!new_setting)
883                 return -EINVAL;
884 
885         if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
886                 return -EFAULT;
887 
888         if (!timespec_valid(&new_spec.it_interval) ||
889             !timespec_valid(&new_spec.it_value))
890                 return -EINVAL;
891 retry:
892         timr = lock_timer(timer_id, &flag);
893         if (!timr)
894                 return -EINVAL;
895 
896         kc = clockid_to_kclock(timr->it_clock);
897         if (WARN_ON_ONCE(!kc || !kc->timer_set))
898                 error = -EINVAL;
899         else
900                 error = kc->timer_set(timr, flags, &new_spec, rtn);
901 
902         unlock_timer(timr, flag);
903         if (error == TIMER_RETRY) {
904                 rtn = NULL;     // We already got the old time...
905                 goto retry;
906         }
907 
908         if (old_setting && !error &&
909             copy_to_user(old_setting, &old_spec, sizeof (old_spec)))
910                 error = -EFAULT;
911 
912         return error;
913 }
914 
915 static int common_timer_del(struct k_itimer *timer)
916 {
917         timer->it.real.interval.tv64 = 0;
918 
919         if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0)
920                 return TIMER_RETRY;
921         return 0;
922 }
923 
924 static inline int timer_delete_hook(struct k_itimer *timer)
925 {
926         struct k_clock *kc = clockid_to_kclock(timer->it_clock);
927 
928         if (WARN_ON_ONCE(!kc || !kc->timer_del))
929                 return -EINVAL;
930         return kc->timer_del(timer);
931 }
932 
933 /* Delete a POSIX.1b interval timer. */
934 SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
935 {
936         struct k_itimer *timer;
937         unsigned long flags;
938 
939 retry_delete:
940         timer = lock_timer(timer_id, &flags);
941         if (!timer)
942                 return -EINVAL;
943 
944         if (timer_delete_hook(timer) == TIMER_RETRY) {
945                 unlock_timer(timer, flags);
946                 goto retry_delete;
947         }
948 
949         spin_lock(&current->sighand->siglock);
950         list_del(&timer->list);
951         spin_unlock(&current->sighand->siglock);
952         /*
953          * This keeps any tasks waiting on the spin lock from thinking
954          * they got something (see the lock code above).
955          */
956         timer->it_signal = NULL;
957 
958         unlock_timer(timer, flags);
959         release_posix_timer(timer, IT_ID_SET);
960         return 0;
961 }
962 
963 /*
964  * return timer owned by the process, used by exit_itimers
965  */
966 static void itimer_delete(struct k_itimer *timer)
967 {
968         unsigned long flags;
969 
970 retry_delete:
971         spin_lock_irqsave(&timer->it_lock, flags);
972 
973         if (timer_delete_hook(timer) == TIMER_RETRY) {
974                 unlock_timer(timer, flags);
975                 goto retry_delete;
976         }
977         list_del(&timer->list);
978         /*
979          * This keeps any tasks waiting on the spin lock from thinking
980          * they got something (see the lock code above).
981          */
982         timer->it_signal = NULL;
983 
984         unlock_timer(timer, flags);
985         release_posix_timer(timer, IT_ID_SET);
986 }
987 
988 /*
989  * This is called by do_exit or de_thread, only when there are no more
990  * references to the shared signal_struct.
991  */
992 void exit_itimers(struct signal_struct *sig)
993 {
994         struct k_itimer *tmr;
995 
996         while (!list_empty(&sig->posix_timers)) {
997                 tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
998                 itimer_delete(tmr);
999         }
1000 }
1001 
1002 SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
1003                 const struct timespec __user *, tp)
1004 {
1005         struct k_clock *kc = clockid_to_kclock(which_clock);
1006         struct timespec new_tp;
1007 
1008         if (!kc || !kc->clock_set)
1009                 return -EINVAL;
1010 
1011         if (copy_from_user(&new_tp, tp, sizeof (*tp)))
1012                 return -EFAULT;
1013 
1014         return kc->clock_set(which_clock, &new_tp);
1015 }
1016 
1017 SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
1018                 struct timespec __user *,tp)
1019 {
1020         struct k_clock *kc = clockid_to_kclock(which_clock);
1021         struct timespec kernel_tp;
1022         int error;
1023 
1024         if (!kc)
1025                 return -EINVAL;
1026 
1027         error = kc->clock_get(which_clock, &kernel_tp);
1028 
1029         if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
1030                 error = -EFAULT;
1031 
1032         return error;
1033 }
1034 
1035 SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
1036                 struct timex __user *, utx)
1037 {
1038         struct k_clock *kc = clockid_to_kclock(which_clock);
1039         struct timex ktx;
1040         int err;
1041 
1042         if (!kc)
1043                 return -EINVAL;
1044         if (!kc->clock_adj)
1045                 return -EOPNOTSUPP;
1046 
1047         if (copy_from_user(&ktx, utx, sizeof(ktx)))
1048                 return -EFAULT;
1049 
1050         err = kc->clock_adj(which_clock, &ktx);
1051 
1052         if (err >= 0 && copy_to_user(utx, &ktx, sizeof(ktx)))
1053                 return -EFAULT;
1054 
1055         return err;
1056 }
1057 
1058 SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
1059                 struct timespec __user *, tp)
1060 {
1061         struct k_clock *kc = clockid_to_kclock(which_clock);
1062         struct timespec rtn_tp;
1063         int error;
1064 
1065         if (!kc)
1066                 return -EINVAL;
1067 
1068         error = kc->clock_getres(which_clock, &rtn_tp);
1069 
1070         if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp)))
1071                 error = -EFAULT;
1072 
1073         return error;
1074 }
1075 
1076 /*
1077  * nanosleep for monotonic and realtime clocks
1078  */
1079 static int common_nsleep(const clockid_t which_clock, int flags,
1080                          struct timespec *tsave, struct timespec __user *rmtp)
1081 {
1082         return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
1083                                  HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
1084                                  which_clock);
1085 }
1086 
1087 SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
1088                 const struct timespec __user *, rqtp,
1089                 struct timespec __user *, rmtp)
1090 {
1091         struct k_clock *kc = clockid_to_kclock(which_clock);
1092         struct timespec t;
1093 
1094         if (!kc)
1095                 return -EINVAL;
1096         if (!kc->nsleep)
1097                 return -ENANOSLEEP_NOTSUP;
1098 
1099         if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
1100                 return -EFAULT;
1101 
1102         if (!timespec_valid(&t))
1103                 return -EINVAL;
1104 
1105         return kc->nsleep(which_clock, flags, &t, rmtp);
1106 }
1107 
1108 /*
1109  * This will restart clock_nanosleep. This is required only by
1110  * compat_clock_nanosleep_restart for now.
1111  */
1112 long clock_nanosleep_restart(struct restart_block *restart_block)
1113 {
1114         clockid_t which_clock = restart_block->nanosleep.clockid;
1115         struct k_clock *kc = clockid_to_kclock(which_clock);
1116 
1117         if (WARN_ON_ONCE(!kc || !kc->nsleep_restart))
1118                 return -EINVAL;
1119 
1120         return kc->nsleep_restart(restart_block);
1121 }
1122 

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