Root/kernel/posix-timers.c

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 */
64static struct kmem_cache *posix_timers_cache;
65
66static DEFINE_HASHTABLE(posix_timers_hashtable, 9);
67static 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
125static struct k_clock posix_clocks[MAX_CLOCKS];
126
127/*
128 * These ones are defined below.
129 */
130static int common_nsleep(const clockid_t, int flags, struct timespec *t,
131             struct timespec __user *rmtp);
132static int common_timer_create(struct k_itimer *new_timer);
133static void common_timer_get(struct k_itimer *, struct itimerspec *);
134static int common_timer_set(struct k_itimer *, int,
135                struct itimerspec *, struct itimerspec *);
136static int common_timer_del(struct k_itimer *timer);
137
138static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
139
140static 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
148static 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
153static 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
166static 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
174static 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
198static 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 */
204static 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 */
211static 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
217static 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 */
226static 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 */
235static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
236{
237    getrawmonotonic(tp);
238    return 0;
239}
240
241
242static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp)
243{
244    *tp = current_kernel_time();
245    return 0;
246}
247
248static int posix_get_monotonic_coarse(clockid_t which_clock,
249                        struct timespec *tp)
250{
251    *tp = get_monotonic_coarse();
252    return 0;
253}
254
255static 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
261static int posix_get_boottime(const clockid_t which_clock, struct timespec *tp)
262{
263    get_monotonic_boottime(tp);
264    return 0;
265}
266
267static 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 */
276static __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
349static 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 */
377void 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
397int 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}
424EXPORT_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 */
433static 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
497static 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
514void 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}
536EXPORT_SYMBOL_GPL(posix_timers_register_clock);
537
538static 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
552static 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
561static 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
574static 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
585static 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
593SYSCALL_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     */
671out:
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 */
683static 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 */
725static void
726common_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. */
767SYSCALL_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 */
803SYSCALL_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. */
821static int
822common_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 */
871SYSCALL_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;
891retry:
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
915static 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
924static 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. */
934SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
935{
936    struct k_itimer *timer;
937    unsigned long flags;
938
939retry_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 */
966static void itimer_delete(struct k_itimer *timer)
967{
968    unsigned long flags;
969
970retry_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 */
992void 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
1002SYSCALL_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
1017SYSCALL_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
1035SYSCALL_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
1058SYSCALL_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 */
1079static 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
1087SYSCALL_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 */
1112long 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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