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/idr.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
51/*
52 * Management arrays for POSIX timers. Timers are kept in slab memory
53 * Timer ids are allocated by an external routine that keeps track of the
54 * id and the timer. The external interface is:
55 *
56 * void *idr_find(struct idr *idp, int id); to find timer_id <id>
57 * int idr_get_new(struct idr *idp, void *ptr); to get a new id and
58 * related it to <ptr>
59 * void idr_remove(struct idr *idp, int id); to release <id>
60 * void idr_init(struct idr *idp); to initialize <idp>
61 * which we supply.
62 * The idr_get_new *may* call slab for more memory so it must not be
63 * called under a spin lock. Likewise idr_remore may release memory
64 * (but it may be ok to do this under a lock...).
65 * idr_find is just a memory look up and is quite fast. A -1 return
66 * indicates that the requested id does not exist.
67 */
68
69/*
70 * Lets keep our timers in a slab cache :-)
71 */
72static struct kmem_cache *posix_timers_cache;
73static struct idr posix_timers_id;
74static DEFINE_SPINLOCK(idr_lock);
75
76/*
77 * we assume that the new SIGEV_THREAD_ID shares no bits with the other
78 * SIGEV values. Here we put out an error if this assumption fails.
79 */
80#if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
81                       ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
82#error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
83#endif
84
85/*
86 * parisc wants ENOTSUP instead of EOPNOTSUPP
87 */
88#ifndef ENOTSUP
89# define ENANOSLEEP_NOTSUP EOPNOTSUPP
90#else
91# define ENANOSLEEP_NOTSUP ENOTSUP
92#endif
93
94/*
95 * The timer ID is turned into a timer address by idr_find().
96 * Verifying a valid ID consists of:
97 *
98 * a) checking that idr_find() returns other than -1.
99 * b) checking that the timer id matches the one in the timer itself.
100 * c) that the timer owner is in the callers thread group.
101 */
102
103/*
104 * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
105 * to implement others. This structure defines the various
106 * clocks.
107 *
108 * RESOLUTION: Clock resolution is used to round up timer and interval
109 * times, NOT to report clock times, which are reported with as
110 * much resolution as the system can muster. In some cases this
111 * resolution may depend on the underlying clock hardware and
112 * may not be quantifiable until run time, and only then is the
113 * necessary code is written. The standard says we should say
114 * something about this issue in the documentation...
115 *
116 * FUNCTIONS: The CLOCKs structure defines possible functions to
117 * handle various clock functions.
118 *
119 * The standard POSIX timer management code assumes the
120 * following: 1.) The k_itimer struct (sched.h) is used for
121 * the timer. 2.) The list, it_lock, it_clock, it_id and
122 * it_pid fields are not modified by timer code.
123 *
124 * Permissions: It is assumed that the clock_settime() function defined
125 * for each clock will take care of permission checks. Some
126 * clocks may be set able by any user (i.e. local process
127 * clocks) others not. Currently the only set able clock we
128 * have is CLOCK_REALTIME and its high res counter part, both of
129 * which we beg off on and pass to do_sys_settimeofday().
130 */
131
132static struct k_clock posix_clocks[MAX_CLOCKS];
133
134/*
135 * These ones are defined below.
136 */
137static int common_nsleep(const clockid_t, int flags, struct timespec *t,
138             struct timespec __user *rmtp);
139static int common_timer_create(struct k_itimer *new_timer);
140static void common_timer_get(struct k_itimer *, struct itimerspec *);
141static int common_timer_set(struct k_itimer *, int,
142                struct itimerspec *, struct itimerspec *);
143static int common_timer_del(struct k_itimer *timer);
144
145static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
146
147static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
148
149#define lock_timer(tid, flags) \
150({ struct k_itimer *__timr; \
151    __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags)); \
152    __timr; \
153})
154
155static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
156{
157    spin_unlock_irqrestore(&timr->it_lock, flags);
158}
159
160/* Get clock_realtime */
161static int posix_clock_realtime_get(clockid_t which_clock, struct timespec *tp)
162{
163    ktime_get_real_ts(tp);
164    return 0;
165}
166
167/* Set clock_realtime */
168static int posix_clock_realtime_set(const clockid_t which_clock,
169                    const struct timespec *tp)
170{
171    return do_sys_settimeofday(tp, NULL);
172}
173
174static int posix_clock_realtime_adj(const clockid_t which_clock,
175                    struct timex *t)
176{
177    return do_adjtimex(t);
178}
179
180/*
181 * Get monotonic time for posix timers
182 */
183static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
184{
185    ktime_get_ts(tp);
186    return 0;
187}
188
189/*
190 * Get monotonic-raw time for posix timers
191 */
192static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
193{
194    getrawmonotonic(tp);
195    return 0;
196}
197
198
199static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp)
200{
201    *tp = current_kernel_time();
202    return 0;
203}
204
205static int posix_get_monotonic_coarse(clockid_t which_clock,
206                        struct timespec *tp)
207{
208    *tp = get_monotonic_coarse();
209    return 0;
210}
211
212static int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp)
213{
214    *tp = ktime_to_timespec(KTIME_LOW_RES);
215    return 0;
216}
217
218static int posix_get_boottime(const clockid_t which_clock, struct timespec *tp)
219{
220    get_monotonic_boottime(tp);
221    return 0;
222}
223
224
225/*
226 * Initialize everything, well, just everything in Posix clocks/timers ;)
227 */
228static __init int init_posix_timers(void)
229{
230    struct k_clock clock_realtime = {
231        .clock_getres = hrtimer_get_res,
232        .clock_get = posix_clock_realtime_get,
233        .clock_set = posix_clock_realtime_set,
234        .clock_adj = posix_clock_realtime_adj,
235        .nsleep = common_nsleep,
236        .nsleep_restart = hrtimer_nanosleep_restart,
237        .timer_create = common_timer_create,
238        .timer_set = common_timer_set,
239        .timer_get = common_timer_get,
240        .timer_del = common_timer_del,
241    };
242    struct k_clock clock_monotonic = {
243        .clock_getres = hrtimer_get_res,
244        .clock_get = posix_ktime_get_ts,
245        .nsleep = common_nsleep,
246        .nsleep_restart = hrtimer_nanosleep_restart,
247        .timer_create = common_timer_create,
248        .timer_set = common_timer_set,
249        .timer_get = common_timer_get,
250        .timer_del = common_timer_del,
251    };
252    struct k_clock clock_monotonic_raw = {
253        .clock_getres = hrtimer_get_res,
254        .clock_get = posix_get_monotonic_raw,
255    };
256    struct k_clock clock_realtime_coarse = {
257        .clock_getres = posix_get_coarse_res,
258        .clock_get = posix_get_realtime_coarse,
259    };
260    struct k_clock clock_monotonic_coarse = {
261        .clock_getres = posix_get_coarse_res,
262        .clock_get = posix_get_monotonic_coarse,
263    };
264    struct k_clock clock_boottime = {
265        .clock_getres = hrtimer_get_res,
266        .clock_get = posix_get_boottime,
267        .nsleep = common_nsleep,
268        .nsleep_restart = hrtimer_nanosleep_restart,
269        .timer_create = common_timer_create,
270        .timer_set = common_timer_set,
271        .timer_get = common_timer_get,
272        .timer_del = common_timer_del,
273    };
274
275    posix_timers_register_clock(CLOCK_REALTIME, &clock_realtime);
276    posix_timers_register_clock(CLOCK_MONOTONIC, &clock_monotonic);
277    posix_timers_register_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
278    posix_timers_register_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
279    posix_timers_register_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
280    posix_timers_register_clock(CLOCK_BOOTTIME, &clock_boottime);
281
282    posix_timers_cache = kmem_cache_create("posix_timers_cache",
283                    sizeof (struct k_itimer), 0, SLAB_PANIC,
284                    NULL);
285    idr_init(&posix_timers_id);
286    return 0;
287}
288
289__initcall(init_posix_timers);
290
291static void schedule_next_timer(struct k_itimer *timr)
292{
293    struct hrtimer *timer = &timr->it.real.timer;
294
295    if (timr->it.real.interval.tv64 == 0)
296        return;
297
298    timr->it_overrun += (unsigned int) hrtimer_forward(timer,
299                        timer->base->get_time(),
300                        timr->it.real.interval);
301
302    timr->it_overrun_last = timr->it_overrun;
303    timr->it_overrun = -1;
304    ++timr->it_requeue_pending;
305    hrtimer_restart(timer);
306}
307
308/*
309 * This function is exported for use by the signal deliver code. It is
310 * called just prior to the info block being released and passes that
311 * block to us. It's function is to update the overrun entry AND to
312 * restart the timer. It should only be called if the timer is to be
313 * restarted (i.e. we have flagged this in the sys_private entry of the
314 * info block).
315 *
316 * To protect against the timer going away while the interrupt is queued,
317 * we require that the it_requeue_pending flag be set.
318 */
319void do_schedule_next_timer(struct siginfo *info)
320{
321    struct k_itimer *timr;
322    unsigned long flags;
323
324    timr = lock_timer(info->si_tid, &flags);
325
326    if (timr && timr->it_requeue_pending == info->si_sys_private) {
327        if (timr->it_clock < 0)
328            posix_cpu_timer_schedule(timr);
329        else
330            schedule_next_timer(timr);
331
332        info->si_overrun += timr->it_overrun_last;
333    }
334
335    if (timr)
336        unlock_timer(timr, flags);
337}
338
339int posix_timer_event(struct k_itimer *timr, int si_private)
340{
341    struct task_struct *task;
342    int shared, ret = -1;
343    /*
344     * FIXME: if ->sigq is queued we can race with
345     * dequeue_signal()->do_schedule_next_timer().
346     *
347     * If dequeue_signal() sees the "right" value of
348     * si_sys_private it calls do_schedule_next_timer().
349     * We re-queue ->sigq and drop ->it_lock().
350     * do_schedule_next_timer() locks the timer
351     * and re-schedules it while ->sigq is pending.
352     * Not really bad, but not that we want.
353     */
354    timr->sigq->info.si_sys_private = si_private;
355
356    rcu_read_lock();
357    task = pid_task(timr->it_pid, PIDTYPE_PID);
358    if (task) {
359        shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
360        ret = send_sigqueue(timr->sigq, task, shared);
361    }
362    rcu_read_unlock();
363    /* If we failed to send the signal the timer stops. */
364    return ret > 0;
365}
366EXPORT_SYMBOL_GPL(posix_timer_event);
367
368/*
369 * This function gets called when a POSIX.1b interval timer expires. It
370 * is used as a callback from the kernel internal timer. The
371 * run_timer_list code ALWAYS calls with interrupts on.
372
373 * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
374 */
375static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
376{
377    struct k_itimer *timr;
378    unsigned long flags;
379    int si_private = 0;
380    enum hrtimer_restart ret = HRTIMER_NORESTART;
381
382    timr = container_of(timer, struct k_itimer, it.real.timer);
383    spin_lock_irqsave(&timr->it_lock, flags);
384
385    if (timr->it.real.interval.tv64 != 0)
386        si_private = ++timr->it_requeue_pending;
387
388    if (posix_timer_event(timr, si_private)) {
389        /*
390         * signal was not sent because of sig_ignor
391         * we will not get a call back to restart it AND
392         * it should be restarted.
393         */
394        if (timr->it.real.interval.tv64 != 0) {
395            ktime_t now = hrtimer_cb_get_time(timer);
396
397            /*
398             * FIXME: What we really want, is to stop this
399             * timer completely and restart it in case the
400             * SIG_IGN is removed. This is a non trivial
401             * change which involves sighand locking
402             * (sigh !), which we don't want to do late in
403             * the release cycle.
404             *
405             * For now we just let timers with an interval
406             * less than a jiffie expire every jiffie to
407             * avoid softirq starvation in case of SIG_IGN
408             * and a very small interval, which would put
409             * the timer right back on the softirq pending
410             * list. By moving now ahead of time we trick
411             * hrtimer_forward() to expire the timer
412             * later, while we still maintain the overrun
413             * accuracy, but have some inconsistency in
414             * the timer_gettime() case. This is at least
415             * better than a starved softirq. A more
416             * complex fix which solves also another related
417             * inconsistency is already in the pipeline.
418             */
419#ifdef CONFIG_HIGH_RES_TIMERS
420            {
421                ktime_t kj = ktime_set(0, NSEC_PER_SEC / HZ);
422
423                if (timr->it.real.interval.tv64 < kj.tv64)
424                    now = ktime_add(now, kj);
425            }
426#endif
427            timr->it_overrun += (unsigned int)
428                hrtimer_forward(timer, now,
429                        timr->it.real.interval);
430            ret = HRTIMER_RESTART;
431            ++timr->it_requeue_pending;
432        }
433    }
434
435    unlock_timer(timr, flags);
436    return ret;
437}
438
439static struct pid *good_sigevent(sigevent_t * event)
440{
441    struct task_struct *rtn = current->group_leader;
442
443    if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
444        (!(rtn = find_task_by_vpid(event->sigev_notify_thread_id)) ||
445         !same_thread_group(rtn, current) ||
446         (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
447        return NULL;
448
449    if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
450        ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
451        return NULL;
452
453    return task_pid(rtn);
454}
455
456void posix_timers_register_clock(const clockid_t clock_id,
457                 struct k_clock *new_clock)
458{
459    if ((unsigned) clock_id >= MAX_CLOCKS) {
460        printk(KERN_WARNING "POSIX clock register failed for clock_id %d\n",
461               clock_id);
462        return;
463    }
464
465    if (!new_clock->clock_get) {
466        printk(KERN_WARNING "POSIX clock id %d lacks clock_get()\n",
467               clock_id);
468        return;
469    }
470    if (!new_clock->clock_getres) {
471        printk(KERN_WARNING "POSIX clock id %d lacks clock_getres()\n",
472               clock_id);
473        return;
474    }
475
476    posix_clocks[clock_id] = *new_clock;
477}
478EXPORT_SYMBOL_GPL(posix_timers_register_clock);
479
480static struct k_itimer * alloc_posix_timer(void)
481{
482    struct k_itimer *tmr;
483    tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
484    if (!tmr)
485        return tmr;
486    if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
487        kmem_cache_free(posix_timers_cache, tmr);
488        return NULL;
489    }
490    memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
491    return tmr;
492}
493
494static void k_itimer_rcu_free(struct rcu_head *head)
495{
496    struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu);
497
498    kmem_cache_free(posix_timers_cache, tmr);
499}
500
501#define IT_ID_SET 1
502#define IT_ID_NOT_SET 0
503static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
504{
505    if (it_id_set) {
506        unsigned long flags;
507        spin_lock_irqsave(&idr_lock, flags);
508        idr_remove(&posix_timers_id, tmr->it_id);
509        spin_unlock_irqrestore(&idr_lock, flags);
510    }
511    put_pid(tmr->it_pid);
512    sigqueue_free(tmr->sigq);
513    call_rcu(&tmr->it.rcu, k_itimer_rcu_free);
514}
515
516static struct k_clock *clockid_to_kclock(const clockid_t id)
517{
518    if (id < 0)
519        return (id & CLOCKFD_MASK) == CLOCKFD ?
520            &clock_posix_dynamic : &clock_posix_cpu;
521
522    if (id >= MAX_CLOCKS || !posix_clocks[id].clock_getres)
523        return NULL;
524    return &posix_clocks[id];
525}
526
527static int common_timer_create(struct k_itimer *new_timer)
528{
529    hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
530    return 0;
531}
532
533/* Create a POSIX.1b interval timer. */
534
535SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
536        struct sigevent __user *, timer_event_spec,
537        timer_t __user *, created_timer_id)
538{
539    struct k_clock *kc = clockid_to_kclock(which_clock);
540    struct k_itimer *new_timer;
541    int error, new_timer_id;
542    sigevent_t event;
543    int it_id_set = IT_ID_NOT_SET;
544
545    if (!kc)
546        return -EINVAL;
547    if (!kc->timer_create)
548        return -EOPNOTSUPP;
549
550    new_timer = alloc_posix_timer();
551    if (unlikely(!new_timer))
552        return -EAGAIN;
553
554    spin_lock_init(&new_timer->it_lock);
555 retry:
556    if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) {
557        error = -EAGAIN;
558        goto out;
559    }
560    spin_lock_irq(&idr_lock);
561    error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id);
562    spin_unlock_irq(&idr_lock);
563    if (error) {
564        if (error == -EAGAIN)
565            goto retry;
566        /*
567         * Weird looking, but we return EAGAIN if the IDR is
568         * full (proper POSIX return value for this)
569         */
570        error = -EAGAIN;
571        goto out;
572    }
573
574    it_id_set = IT_ID_SET;
575    new_timer->it_id = (timer_t) new_timer_id;
576    new_timer->it_clock = which_clock;
577    new_timer->it_overrun = -1;
578
579    if (timer_event_spec) {
580        if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
581            error = -EFAULT;
582            goto out;
583        }
584        rcu_read_lock();
585        new_timer->it_pid = get_pid(good_sigevent(&event));
586        rcu_read_unlock();
587        if (!new_timer->it_pid) {
588            error = -EINVAL;
589            goto out;
590        }
591    } else {
592        event.sigev_notify = SIGEV_SIGNAL;
593        event.sigev_signo = SIGALRM;
594        event.sigev_value.sival_int = new_timer->it_id;
595        new_timer->it_pid = get_pid(task_tgid(current));
596    }
597
598    new_timer->it_sigev_notify = event.sigev_notify;
599    new_timer->sigq->info.si_signo = event.sigev_signo;
600    new_timer->sigq->info.si_value = event.sigev_value;
601    new_timer->sigq->info.si_tid = new_timer->it_id;
602    new_timer->sigq->info.si_code = SI_TIMER;
603
604    if (copy_to_user(created_timer_id,
605             &new_timer_id, sizeof (new_timer_id))) {
606        error = -EFAULT;
607        goto out;
608    }
609
610    error = kc->timer_create(new_timer);
611    if (error)
612        goto out;
613
614    spin_lock_irq(&current->sighand->siglock);
615    new_timer->it_signal = current->signal;
616    list_add(&new_timer->list, &current->signal->posix_timers);
617    spin_unlock_irq(&current->sighand->siglock);
618
619    return 0;
620    /*
621     * In the case of the timer belonging to another task, after
622     * the task is unlocked, the timer is owned by the other task
623     * and may cease to exist at any time. Don't use or modify
624     * new_timer after the unlock call.
625     */
626out:
627    release_posix_timer(new_timer, it_id_set);
628    return error;
629}
630
631/*
632 * Locking issues: We need to protect the result of the id look up until
633 * we get the timer locked down so it is not deleted under us. The
634 * removal is done under the idr spinlock so we use that here to bridge
635 * the find to the timer lock. To avoid a dead lock, the timer id MUST
636 * be release with out holding the timer lock.
637 */
638static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
639{
640    struct k_itimer *timr;
641
642    rcu_read_lock();
643    timr = idr_find(&posix_timers_id, (int)timer_id);
644    if (timr) {
645        spin_lock_irqsave(&timr->it_lock, *flags);
646        if (timr->it_signal == current->signal) {
647            rcu_read_unlock();
648            return timr;
649        }
650        spin_unlock_irqrestore(&timr->it_lock, *flags);
651    }
652    rcu_read_unlock();
653
654    return NULL;
655}
656
657/*
658 * Get the time remaining on a POSIX.1b interval timer. This function
659 * is ALWAYS called with spin_lock_irq on the timer, thus it must not
660 * mess with irq.
661 *
662 * We have a couple of messes to clean up here. First there is the case
663 * of a timer that has a requeue pending. These timers should appear to
664 * be in the timer list with an expiry as if we were to requeue them
665 * now.
666 *
667 * The second issue is the SIGEV_NONE timer which may be active but is
668 * not really ever put in the timer list (to save system resources).
669 * This timer may be expired, and if so, we will do it here. Otherwise
670 * it is the same as a requeue pending timer WRT to what we should
671 * report.
672 */
673static void
674common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
675{
676    ktime_t now, remaining, iv;
677    struct hrtimer *timer = &timr->it.real.timer;
678
679    memset(cur_setting, 0, sizeof(struct itimerspec));
680
681    iv = timr->it.real.interval;
682
683    /* interval timer ? */
684    if (iv.tv64)
685        cur_setting->it_interval = ktime_to_timespec(iv);
686    else if (!hrtimer_active(timer) &&
687         (timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
688        return;
689
690    now = timer->base->get_time();
691
692    /*
693     * When a requeue is pending or this is a SIGEV_NONE
694     * timer move the expiry time forward by intervals, so
695     * expiry is > now.
696     */
697    if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
698        (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
699        timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
700
701    remaining = ktime_sub(hrtimer_get_expires(timer), now);
702    /* Return 0 only, when the timer is expired and not pending */
703    if (remaining.tv64 <= 0) {
704        /*
705         * A single shot SIGEV_NONE timer must return 0, when
706         * it is expired !
707         */
708        if ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
709            cur_setting->it_value.tv_nsec = 1;
710    } else
711        cur_setting->it_value = ktime_to_timespec(remaining);
712}
713
714/* Get the time remaining on a POSIX.1b interval timer. */
715SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
716        struct itimerspec __user *, setting)
717{
718    struct itimerspec cur_setting;
719    struct k_itimer *timr;
720    struct k_clock *kc;
721    unsigned long flags;
722    int ret = 0;
723
724    timr = lock_timer(timer_id, &flags);
725    if (!timr)
726        return -EINVAL;
727
728    kc = clockid_to_kclock(timr->it_clock);
729    if (WARN_ON_ONCE(!kc || !kc->timer_get))
730        ret = -EINVAL;
731    else
732        kc->timer_get(timr, &cur_setting);
733
734    unlock_timer(timr, flags);
735
736    if (!ret && copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
737        return -EFAULT;
738
739    return ret;
740}
741
742/*
743 * Get the number of overruns of a POSIX.1b interval timer. This is to
744 * be the overrun of the timer last delivered. At the same time we are
745 * accumulating overruns on the next timer. The overrun is frozen when
746 * the signal is delivered, either at the notify time (if the info block
747 * is not queued) or at the actual delivery time (as we are informed by
748 * the call back to do_schedule_next_timer(). So all we need to do is
749 * to pick up the frozen overrun.
750 */
751SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
752{
753    struct k_itimer *timr;
754    int overrun;
755    unsigned long flags;
756
757    timr = lock_timer(timer_id, &flags);
758    if (!timr)
759        return -EINVAL;
760
761    overrun = timr->it_overrun_last;
762    unlock_timer(timr, flags);
763
764    return overrun;
765}
766
767/* Set a POSIX.1b interval timer. */
768/* timr->it_lock is taken. */
769static int
770common_timer_set(struct k_itimer *timr, int flags,
771         struct itimerspec *new_setting, struct itimerspec *old_setting)
772{
773    struct hrtimer *timer = &timr->it.real.timer;
774    enum hrtimer_mode mode;
775
776    if (old_setting)
777        common_timer_get(timr, old_setting);
778
779    /* disable the timer */
780    timr->it.real.interval.tv64 = 0;
781    /*
782     * careful here. If smp we could be in the "fire" routine which will
783     * be spinning as we hold the lock. But this is ONLY an SMP issue.
784     */
785    if (hrtimer_try_to_cancel(timer) < 0)
786        return TIMER_RETRY;
787
788    timr->it_requeue_pending = (timr->it_requeue_pending + 2) &
789        ~REQUEUE_PENDING;
790    timr->it_overrun_last = 0;
791
792    /* switch off the timer when it_value is zero */
793    if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
794        return 0;
795
796    mode = flags & TIMER_ABSTIME ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
797    hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
798    timr->it.real.timer.function = posix_timer_fn;
799
800    hrtimer_set_expires(timer, timespec_to_ktime(new_setting->it_value));
801
802    /* Convert interval */
803    timr->it.real.interval = timespec_to_ktime(new_setting->it_interval);
804
805    /* SIGEV_NONE timers are not queued ! See common_timer_get */
806    if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
807        /* Setup correct expiry time for relative timers */
808        if (mode == HRTIMER_MODE_REL) {
809            hrtimer_add_expires(timer, timer->base->get_time());
810        }
811        return 0;
812    }
813
814    hrtimer_start_expires(timer, mode);
815    return 0;
816}
817
818/* Set a POSIX.1b interval timer */
819SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
820        const struct itimerspec __user *, new_setting,
821        struct itimerspec __user *, old_setting)
822{
823    struct k_itimer *timr;
824    struct itimerspec new_spec, old_spec;
825    int error = 0;
826    unsigned long flag;
827    struct itimerspec *rtn = old_setting ? &old_spec : NULL;
828    struct k_clock *kc;
829
830    if (!new_setting)
831        return -EINVAL;
832
833    if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
834        return -EFAULT;
835
836    if (!timespec_valid(&new_spec.it_interval) ||
837        !timespec_valid(&new_spec.it_value))
838        return -EINVAL;
839retry:
840    timr = lock_timer(timer_id, &flag);
841    if (!timr)
842        return -EINVAL;
843
844    kc = clockid_to_kclock(timr->it_clock);
845    if (WARN_ON_ONCE(!kc || !kc->timer_set))
846        error = -EINVAL;
847    else
848        error = kc->timer_set(timr, flags, &new_spec, rtn);
849
850    unlock_timer(timr, flag);
851    if (error == TIMER_RETRY) {
852        rtn = NULL; // We already got the old time...
853        goto retry;
854    }
855
856    if (old_setting && !error &&
857        copy_to_user(old_setting, &old_spec, sizeof (old_spec)))
858        error = -EFAULT;
859
860    return error;
861}
862
863static int common_timer_del(struct k_itimer *timer)
864{
865    timer->it.real.interval.tv64 = 0;
866
867    if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0)
868        return TIMER_RETRY;
869    return 0;
870}
871
872static inline int timer_delete_hook(struct k_itimer *timer)
873{
874    struct k_clock *kc = clockid_to_kclock(timer->it_clock);
875
876    if (WARN_ON_ONCE(!kc || !kc->timer_del))
877        return -EINVAL;
878    return kc->timer_del(timer);
879}
880
881/* Delete a POSIX.1b interval timer. */
882SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
883{
884    struct k_itimer *timer;
885    unsigned long flags;
886
887retry_delete:
888    timer = lock_timer(timer_id, &flags);
889    if (!timer)
890        return -EINVAL;
891
892    if (timer_delete_hook(timer) == TIMER_RETRY) {
893        unlock_timer(timer, flags);
894        goto retry_delete;
895    }
896
897    spin_lock(&current->sighand->siglock);
898    list_del(&timer->list);
899    spin_unlock(&current->sighand->siglock);
900    /*
901     * This keeps any tasks waiting on the spin lock from thinking
902     * they got something (see the lock code above).
903     */
904    timer->it_signal = NULL;
905
906    unlock_timer(timer, flags);
907    release_posix_timer(timer, IT_ID_SET);
908    return 0;
909}
910
911/*
912 * return timer owned by the process, used by exit_itimers
913 */
914static void itimer_delete(struct k_itimer *timer)
915{
916    unsigned long flags;
917
918retry_delete:
919    spin_lock_irqsave(&timer->it_lock, flags);
920
921    if (timer_delete_hook(timer) == TIMER_RETRY) {
922        unlock_timer(timer, flags);
923        goto retry_delete;
924    }
925    list_del(&timer->list);
926    /*
927     * This keeps any tasks waiting on the spin lock from thinking
928     * they got something (see the lock code above).
929     */
930    timer->it_signal = NULL;
931
932    unlock_timer(timer, flags);
933    release_posix_timer(timer, IT_ID_SET);
934}
935
936/*
937 * This is called by do_exit or de_thread, only when there are no more
938 * references to the shared signal_struct.
939 */
940void exit_itimers(struct signal_struct *sig)
941{
942    struct k_itimer *tmr;
943
944    while (!list_empty(&sig->posix_timers)) {
945        tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
946        itimer_delete(tmr);
947    }
948}
949
950SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
951        const struct timespec __user *, tp)
952{
953    struct k_clock *kc = clockid_to_kclock(which_clock);
954    struct timespec new_tp;
955
956    if (!kc || !kc->clock_set)
957        return -EINVAL;
958
959    if (copy_from_user(&new_tp, tp, sizeof (*tp)))
960        return -EFAULT;
961
962    return kc->clock_set(which_clock, &new_tp);
963}
964
965SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
966        struct timespec __user *,tp)
967{
968    struct k_clock *kc = clockid_to_kclock(which_clock);
969    struct timespec kernel_tp;
970    int error;
971
972    if (!kc)
973        return -EINVAL;
974
975    error = kc->clock_get(which_clock, &kernel_tp);
976
977    if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
978        error = -EFAULT;
979
980    return error;
981}
982
983SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
984        struct timex __user *, utx)
985{
986    struct k_clock *kc = clockid_to_kclock(which_clock);
987    struct timex ktx;
988    int err;
989
990    if (!kc)
991        return -EINVAL;
992    if (!kc->clock_adj)
993        return -EOPNOTSUPP;
994
995    if (copy_from_user(&ktx, utx, sizeof(ktx)))
996        return -EFAULT;
997
998    err = kc->clock_adj(which_clock, &ktx);
999
1000    if (!err && copy_to_user(utx, &ktx, sizeof(ktx)))
1001        return -EFAULT;
1002
1003    return err;
1004}
1005
1006SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
1007        struct timespec __user *, tp)
1008{
1009    struct k_clock *kc = clockid_to_kclock(which_clock);
1010    struct timespec rtn_tp;
1011    int error;
1012
1013    if (!kc)
1014        return -EINVAL;
1015
1016    error = kc->clock_getres(which_clock, &rtn_tp);
1017
1018    if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp)))
1019        error = -EFAULT;
1020
1021    return error;
1022}
1023
1024/*
1025 * nanosleep for monotonic and realtime clocks
1026 */
1027static int common_nsleep(const clockid_t which_clock, int flags,
1028             struct timespec *tsave, struct timespec __user *rmtp)
1029{
1030    return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
1031                 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
1032                 which_clock);
1033}
1034
1035SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
1036        const struct timespec __user *, rqtp,
1037        struct timespec __user *, rmtp)
1038{
1039    struct k_clock *kc = clockid_to_kclock(which_clock);
1040    struct timespec t;
1041
1042    if (!kc)
1043        return -EINVAL;
1044    if (!kc->nsleep)
1045        return -ENANOSLEEP_NOTSUP;
1046
1047    if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
1048        return -EFAULT;
1049
1050    if (!timespec_valid(&t))
1051        return -EINVAL;
1052
1053    return kc->nsleep(which_clock, flags, &t, rmtp);
1054}
1055
1056/*
1057 * This will restart clock_nanosleep. This is required only by
1058 * compat_clock_nanosleep_restart for now.
1059 */
1060long clock_nanosleep_restart(struct restart_block *restart_block)
1061{
1062    clockid_t which_clock = restart_block->nanosleep.clockid;
1063    struct k_clock *kc = clockid_to_kclock(which_clock);
1064
1065    if (WARN_ON_ONCE(!kc || !kc->nsleep_restart))
1066        return -EINVAL;
1067
1068    return kc->nsleep_restart(restart_block);
1069}
1070

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