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-timers.h>
45#include <linux/syscalls.h>
46#include <linux/wait.h>
47#include <linux/workqueue.h>
48#include <linux/module.h>
49
50/*
51 * Management arrays for POSIX timers. Timers are kept in slab memory
52 * Timer ids are allocated by an external routine that keeps track of the
53 * id and the timer. The external interface is:
54 *
55 * void *idr_find(struct idr *idp, int id); to find timer_id <id>
56 * int idr_get_new(struct idr *idp, void *ptr); to get a new id and
57 * related it to <ptr>
58 * void idr_remove(struct idr *idp, int id); to release <id>
59 * void idr_init(struct idr *idp); to initialize <idp>
60 * which we supply.
61 * The idr_get_new *may* call slab for more memory so it must not be
62 * called under a spin lock. Likewise idr_remore may release memory
63 * (but it may be ok to do this under a lock...).
64 * idr_find is just a memory look up and is quite fast. A -1 return
65 * indicates that the requested id does not exist.
66 */
67
68/*
69 * Lets keep our timers in a slab cache :-)
70 */
71static struct kmem_cache *posix_timers_cache;
72static struct idr posix_timers_id;
73static DEFINE_SPINLOCK(idr_lock);
74
75/*
76 * we assume that the new SIGEV_THREAD_ID shares no bits with the other
77 * SIGEV values. Here we put out an error if this assumption fails.
78 */
79#if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
80                       ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
81#error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
82#endif
83
84
85/*
86 * The timer ID is turned into a timer address by idr_find().
87 * Verifying a valid ID consists of:
88 *
89 * a) checking that idr_find() returns other than -1.
90 * b) checking that the timer id matches the one in the timer itself.
91 * c) that the timer owner is in the callers thread group.
92 */
93
94/*
95 * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
96 * to implement others. This structure defines the various
97 * clocks and allows the possibility of adding others. We
98 * provide an interface to add clocks to the table and expect
99 * the "arch" code to add at least one clock that is high
100 * resolution. Here we define the standard CLOCK_REALTIME as a
101 * 1/HZ resolution clock.
102 *
103 * RESOLUTION: Clock resolution is used to round up timer and interval
104 * times, NOT to report clock times, which are reported with as
105 * much resolution as the system can muster. In some cases this
106 * resolution may depend on the underlying clock hardware and
107 * may not be quantifiable until run time, and only then is the
108 * necessary code is written. The standard says we should say
109 * something about this issue in the documentation...
110 *
111 * FUNCTIONS: The CLOCKs structure defines possible functions to handle
112 * various clock functions. For clocks that use the standard
113 * system timer code these entries should be NULL. This will
114 * allow dispatch without the overhead of indirect function
115 * calls. CLOCKS that depend on other sources (e.g. WWV or GPS)
116 * must supply functions here, even if the function just returns
117 * ENOSYS. The standard POSIX timer management code assumes the
118 * following: 1.) The k_itimer struct (sched.h) is used for the
119 * timer. 2.) The list, it_lock, it_clock, it_id and it_pid
120 * fields are not modified by timer code.
121 *
122 * At this time all functions EXCEPT clock_nanosleep can be
123 * redirected by the CLOCKS structure. Clock_nanosleep is in
124 * there, but the code ignores it.
125 *
126 * Permissions: It is assumed that the clock_settime() function defined
127 * for each clock will take care of permission checks. Some
128 * clocks may be set able by any user (i.e. local process
129 * clocks) others not. Currently the only set able clock we
130 * have is CLOCK_REALTIME and its high res counter part, both of
131 * which we beg off on and pass to do_sys_settimeofday().
132 */
133
134static struct k_clock posix_clocks[MAX_CLOCKS];
135
136/*
137 * These ones are defined below.
138 */
139static int common_nsleep(const clockid_t, int flags, struct timespec *t,
140             struct timespec __user *rmtp);
141static void common_timer_get(struct k_itimer *, struct itimerspec *);
142static int common_timer_set(struct k_itimer *, int,
143                struct itimerspec *, struct itimerspec *);
144static int common_timer_del(struct k_itimer *timer);
145
146static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
147
148static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
149
150#define lock_timer(tid, flags) \
151({ struct k_itimer *__timr; \
152    __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags)); \
153    __timr; \
154})
155
156static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
157{
158    spin_unlock_irqrestore(&timr->it_lock, flags);
159}
160
161/*
162 * Call the k_clock hook function if non-null, or the default function.
163 */
164#define CLOCK_DISPATCH(clock, call, arglist) \
165     ((clock) < 0 ? posix_cpu_##call arglist : \
166      (posix_clocks[clock].call != NULL \
167       ? (*posix_clocks[clock].call) arglist : common_##call arglist))
168
169/*
170 * Default clock hook functions when the struct k_clock passed
171 * to register_posix_clock leaves a function pointer null.
172 *
173 * The function common_CALL is the default implementation for
174 * the function pointer CALL in struct k_clock.
175 */
176
177static inline int common_clock_getres(const clockid_t which_clock,
178                      struct timespec *tp)
179{
180    tp->tv_sec = 0;
181    tp->tv_nsec = posix_clocks[which_clock].res;
182    return 0;
183}
184
185/*
186 * Get real time for posix timers
187 */
188static int common_clock_get(clockid_t which_clock, struct timespec *tp)
189{
190    ktime_get_real_ts(tp);
191    return 0;
192}
193
194static inline int common_clock_set(const clockid_t which_clock,
195                   struct timespec *tp)
196{
197    return do_sys_settimeofday(tp, NULL);
198}
199
200static int common_timer_create(struct k_itimer *new_timer)
201{
202    hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
203    return 0;
204}
205
206static int no_timer_create(struct k_itimer *new_timer)
207{
208    return -EOPNOTSUPP;
209}
210
211static int no_nsleep(const clockid_t which_clock, int flags,
212             struct timespec *tsave, struct timespec __user *rmtp)
213{
214    return -EOPNOTSUPP;
215}
216
217/*
218 * Return nonzero if we know a priori this clockid_t value is bogus.
219 */
220static inline int invalid_clockid(const clockid_t which_clock)
221{
222    if (which_clock < 0) /* CPU clock, posix_cpu_* will check it */
223        return 0;
224    if ((unsigned) which_clock >= MAX_CLOCKS)
225        return 1;
226    if (posix_clocks[which_clock].clock_getres != NULL)
227        return 0;
228    if (posix_clocks[which_clock].res != 0)
229        return 0;
230    return 1;
231}
232
233/*
234 * Get monotonic time for posix timers
235 */
236static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
237{
238    ktime_get_ts(tp);
239    return 0;
240}
241
242/*
243 * Get monotonic time for posix timers
244 */
245static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
246{
247    getrawmonotonic(tp);
248    return 0;
249}
250
251
252static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp)
253{
254    *tp = current_kernel_time();
255    return 0;
256}
257
258static int posix_get_monotonic_coarse(clockid_t which_clock,
259                        struct timespec *tp)
260{
261    *tp = get_monotonic_coarse();
262    return 0;
263}
264
265static int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp)
266{
267    *tp = ktime_to_timespec(KTIME_LOW_RES);
268    return 0;
269}
270/*
271 * Initialize everything, well, just everything in Posix clocks/timers ;)
272 */
273static __init int init_posix_timers(void)
274{
275    struct k_clock clock_realtime = {
276        .clock_getres = hrtimer_get_res,
277    };
278    struct k_clock clock_monotonic = {
279        .clock_getres = hrtimer_get_res,
280        .clock_get = posix_ktime_get_ts,
281        .clock_set = do_posix_clock_nosettime,
282    };
283    struct k_clock clock_monotonic_raw = {
284        .clock_getres = hrtimer_get_res,
285        .clock_get = posix_get_monotonic_raw,
286        .clock_set = do_posix_clock_nosettime,
287        .timer_create = no_timer_create,
288        .nsleep = no_nsleep,
289    };
290    struct k_clock clock_realtime_coarse = {
291        .clock_getres = posix_get_coarse_res,
292        .clock_get = posix_get_realtime_coarse,
293        .clock_set = do_posix_clock_nosettime,
294        .timer_create = no_timer_create,
295        .nsleep = no_nsleep,
296    };
297    struct k_clock clock_monotonic_coarse = {
298        .clock_getres = posix_get_coarse_res,
299        .clock_get = posix_get_monotonic_coarse,
300        .clock_set = do_posix_clock_nosettime,
301        .timer_create = no_timer_create,
302        .nsleep = no_nsleep,
303    };
304
305    register_posix_clock(CLOCK_REALTIME, &clock_realtime);
306    register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic);
307    register_posix_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
308    register_posix_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
309    register_posix_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
310
311    posix_timers_cache = kmem_cache_create("posix_timers_cache",
312                    sizeof (struct k_itimer), 0, SLAB_PANIC,
313                    NULL);
314    idr_init(&posix_timers_id);
315    return 0;
316}
317
318__initcall(init_posix_timers);
319
320static void schedule_next_timer(struct k_itimer *timr)
321{
322    struct hrtimer *timer = &timr->it.real.timer;
323
324    if (timr->it.real.interval.tv64 == 0)
325        return;
326
327    timr->it_overrun += (unsigned int) hrtimer_forward(timer,
328                        timer->base->get_time(),
329                        timr->it.real.interval);
330
331    timr->it_overrun_last = timr->it_overrun;
332    timr->it_overrun = -1;
333    ++timr->it_requeue_pending;
334    hrtimer_restart(timer);
335}
336
337/*
338 * This function is exported for use by the signal deliver code. It is
339 * called just prior to the info block being released and passes that
340 * block to us. It's function is to update the overrun entry AND to
341 * restart the timer. It should only be called if the timer is to be
342 * restarted (i.e. we have flagged this in the sys_private entry of the
343 * info block).
344 *
345 * To protect aginst the timer going away while the interrupt is queued,
346 * we require that the it_requeue_pending flag be set.
347 */
348void do_schedule_next_timer(struct siginfo *info)
349{
350    struct k_itimer *timr;
351    unsigned long flags;
352
353    timr = lock_timer(info->si_tid, &flags);
354
355    if (timr && timr->it_requeue_pending == info->si_sys_private) {
356        if (timr->it_clock < 0)
357            posix_cpu_timer_schedule(timr);
358        else
359            schedule_next_timer(timr);
360
361        info->si_overrun += timr->it_overrun_last;
362    }
363
364    if (timr)
365        unlock_timer(timr, flags);
366}
367
368int posix_timer_event(struct k_itimer *timr, int si_private)
369{
370    struct task_struct *task;
371    int shared, ret = -1;
372    /*
373     * FIXME: if ->sigq is queued we can race with
374     * dequeue_signal()->do_schedule_next_timer().
375     *
376     * If dequeue_signal() sees the "right" value of
377     * si_sys_private it calls do_schedule_next_timer().
378     * We re-queue ->sigq and drop ->it_lock().
379     * do_schedule_next_timer() locks the timer
380     * and re-schedules it while ->sigq is pending.
381     * Not really bad, but not that we want.
382     */
383    timr->sigq->info.si_sys_private = si_private;
384
385    rcu_read_lock();
386    task = pid_task(timr->it_pid, PIDTYPE_PID);
387    if (task) {
388        shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
389        ret = send_sigqueue(timr->sigq, task, shared);
390    }
391    rcu_read_unlock();
392    /* If we failed to send the signal the timer stops. */
393    return ret > 0;
394}
395EXPORT_SYMBOL_GPL(posix_timer_event);
396
397/*
398 * This function gets called when a POSIX.1b interval timer expires. It
399 * is used as a callback from the kernel internal timer. The
400 * run_timer_list code ALWAYS calls with interrupts on.
401
402 * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
403 */
404static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
405{
406    struct k_itimer *timr;
407    unsigned long flags;
408    int si_private = 0;
409    enum hrtimer_restart ret = HRTIMER_NORESTART;
410
411    timr = container_of(timer, struct k_itimer, it.real.timer);
412    spin_lock_irqsave(&timr->it_lock, flags);
413
414    if (timr->it.real.interval.tv64 != 0)
415        si_private = ++timr->it_requeue_pending;
416
417    if (posix_timer_event(timr, si_private)) {
418        /*
419         * signal was not sent because of sig_ignor
420         * we will not get a call back to restart it AND
421         * it should be restarted.
422         */
423        if (timr->it.real.interval.tv64 != 0) {
424            ktime_t now = hrtimer_cb_get_time(timer);
425
426            /*
427             * FIXME: What we really want, is to stop this
428             * timer completely and restart it in case the
429             * SIG_IGN is removed. This is a non trivial
430             * change which involves sighand locking
431             * (sigh !), which we don't want to do late in
432             * the release cycle.
433             *
434             * For now we just let timers with an interval
435             * less than a jiffie expire every jiffie to
436             * avoid softirq starvation in case of SIG_IGN
437             * and a very small interval, which would put
438             * the timer right back on the softirq pending
439             * list. By moving now ahead of time we trick
440             * hrtimer_forward() to expire the timer
441             * later, while we still maintain the overrun
442             * accuracy, but have some inconsistency in
443             * the timer_gettime() case. This is at least
444             * better than a starved softirq. A more
445             * complex fix which solves also another related
446             * inconsistency is already in the pipeline.
447             */
448#ifdef CONFIG_HIGH_RES_TIMERS
449            {
450                ktime_t kj = ktime_set(0, NSEC_PER_SEC / HZ);
451
452                if (timr->it.real.interval.tv64 < kj.tv64)
453                    now = ktime_add(now, kj);
454            }
455#endif
456            timr->it_overrun += (unsigned int)
457                hrtimer_forward(timer, now,
458                        timr->it.real.interval);
459            ret = HRTIMER_RESTART;
460            ++timr->it_requeue_pending;
461        }
462    }
463
464    unlock_timer(timr, flags);
465    return ret;
466}
467
468static struct pid *good_sigevent(sigevent_t * event)
469{
470    struct task_struct *rtn = current->group_leader;
471
472    if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
473        (!(rtn = find_task_by_vpid(event->sigev_notify_thread_id)) ||
474         !same_thread_group(rtn, current) ||
475         (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
476        return NULL;
477
478    if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
479        ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
480        return NULL;
481
482    return task_pid(rtn);
483}
484
485void register_posix_clock(const clockid_t clock_id, struct k_clock *new_clock)
486{
487    if ((unsigned) clock_id >= MAX_CLOCKS) {
488        printk("POSIX clock register failed for clock_id %d\n",
489               clock_id);
490        return;
491    }
492
493    posix_clocks[clock_id] = *new_clock;
494}
495EXPORT_SYMBOL_GPL(register_posix_clock);
496
497static struct k_itimer * alloc_posix_timer(void)
498{
499    struct k_itimer *tmr;
500    tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
501    if (!tmr)
502        return tmr;
503    if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
504        kmem_cache_free(posix_timers_cache, tmr);
505        return NULL;
506    }
507    memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
508    return tmr;
509}
510
511#define IT_ID_SET 1
512#define IT_ID_NOT_SET 0
513static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
514{
515    if (it_id_set) {
516        unsigned long flags;
517        spin_lock_irqsave(&idr_lock, flags);
518        idr_remove(&posix_timers_id, tmr->it_id);
519        spin_unlock_irqrestore(&idr_lock, flags);
520    }
521    put_pid(tmr->it_pid);
522    sigqueue_free(tmr->sigq);
523    kmem_cache_free(posix_timers_cache, tmr);
524}
525
526/* Create a POSIX.1b interval timer. */
527
528SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
529        struct sigevent __user *, timer_event_spec,
530        timer_t __user *, created_timer_id)
531{
532    struct k_itimer *new_timer;
533    int error, new_timer_id;
534    sigevent_t event;
535    int it_id_set = IT_ID_NOT_SET;
536
537    if (invalid_clockid(which_clock))
538        return -EINVAL;
539
540    new_timer = alloc_posix_timer();
541    if (unlikely(!new_timer))
542        return -EAGAIN;
543
544    spin_lock_init(&new_timer->it_lock);
545 retry:
546    if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) {
547        error = -EAGAIN;
548        goto out;
549    }
550    spin_lock_irq(&idr_lock);
551    error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id);
552    spin_unlock_irq(&idr_lock);
553    if (error) {
554        if (error == -EAGAIN)
555            goto retry;
556        /*
557         * Weird looking, but we return EAGAIN if the IDR is
558         * full (proper POSIX return value for this)
559         */
560        error = -EAGAIN;
561        goto out;
562    }
563
564    it_id_set = IT_ID_SET;
565    new_timer->it_id = (timer_t) new_timer_id;
566    new_timer->it_clock = which_clock;
567    new_timer->it_overrun = -1;
568
569    if (timer_event_spec) {
570        if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
571            error = -EFAULT;
572            goto out;
573        }
574        rcu_read_lock();
575        new_timer->it_pid = get_pid(good_sigevent(&event));
576        rcu_read_unlock();
577        if (!new_timer->it_pid) {
578            error = -EINVAL;
579            goto out;
580        }
581    } else {
582        event.sigev_notify = SIGEV_SIGNAL;
583        event.sigev_signo = SIGALRM;
584        event.sigev_value.sival_int = new_timer->it_id;
585        new_timer->it_pid = get_pid(task_tgid(current));
586    }
587
588    new_timer->it_sigev_notify = event.sigev_notify;
589    new_timer->sigq->info.si_signo = event.sigev_signo;
590    new_timer->sigq->info.si_value = event.sigev_value;
591    new_timer->sigq->info.si_tid = new_timer->it_id;
592    new_timer->sigq->info.si_code = SI_TIMER;
593
594    if (copy_to_user(created_timer_id,
595             &new_timer_id, sizeof (new_timer_id))) {
596        error = -EFAULT;
597        goto out;
598    }
599
600    error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
601    if (error)
602        goto out;
603
604    spin_lock_irq(&current->sighand->siglock);
605    new_timer->it_signal = current->signal;
606    list_add(&new_timer->list, &current->signal->posix_timers);
607    spin_unlock_irq(&current->sighand->siglock);
608
609    return 0;
610     /*
611     * In the case of the timer belonging to another task, after
612     * the task is unlocked, the timer is owned by the other task
613     * and may cease to exist at any time. Don't use or modify
614     * new_timer after the unlock call.
615     */
616out:
617    release_posix_timer(new_timer, it_id_set);
618    return error;
619}
620
621/*
622 * Locking issues: We need to protect the result of the id look up until
623 * we get the timer locked down so it is not deleted under us. The
624 * removal is done under the idr spinlock so we use that here to bridge
625 * the find to the timer lock. To avoid a dead lock, the timer id MUST
626 * be release with out holding the timer lock.
627 */
628static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
629{
630    struct k_itimer *timr;
631    /*
632     * Watch out here. We do a irqsave on the idr_lock and pass the
633     * flags part over to the timer lock. Must not let interrupts in
634     * while we are moving the lock.
635     */
636    spin_lock_irqsave(&idr_lock, *flags);
637    timr = idr_find(&posix_timers_id, (int)timer_id);
638    if (timr) {
639        spin_lock(&timr->it_lock);
640        if (timr->it_signal == current->signal) {
641            spin_unlock(&idr_lock);
642            return timr;
643        }
644        spin_unlock(&timr->it_lock);
645    }
646    spin_unlock_irqrestore(&idr_lock, *flags);
647
648    return NULL;
649}
650
651/*
652 * Get the time remaining on a POSIX.1b interval timer. This function
653 * is ALWAYS called with spin_lock_irq on the timer, thus it must not
654 * mess with irq.
655 *
656 * We have a couple of messes to clean up here. First there is the case
657 * of a timer that has a requeue pending. These timers should appear to
658 * be in the timer list with an expiry as if we were to requeue them
659 * now.
660 *
661 * The second issue is the SIGEV_NONE timer which may be active but is
662 * not really ever put in the timer list (to save system resources).
663 * This timer may be expired, and if so, we will do it here. Otherwise
664 * it is the same as a requeue pending timer WRT to what we should
665 * report.
666 */
667static void
668common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
669{
670    ktime_t now, remaining, iv;
671    struct hrtimer *timer = &timr->it.real.timer;
672
673    memset(cur_setting, 0, sizeof(struct itimerspec));
674
675    iv = timr->it.real.interval;
676
677    /* interval timer ? */
678    if (iv.tv64)
679        cur_setting->it_interval = ktime_to_timespec(iv);
680    else if (!hrtimer_active(timer) &&
681         (timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
682        return;
683
684    now = timer->base->get_time();
685
686    /*
687     * When a requeue is pending or this is a SIGEV_NONE
688     * timer move the expiry time forward by intervals, so
689     * expiry is > now.
690     */
691    if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
692        (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
693        timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
694
695    remaining = ktime_sub(hrtimer_get_expires(timer), now);
696    /* Return 0 only, when the timer is expired and not pending */
697    if (remaining.tv64 <= 0) {
698        /*
699         * A single shot SIGEV_NONE timer must return 0, when
700         * it is expired !
701         */
702        if ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
703            cur_setting->it_value.tv_nsec = 1;
704    } else
705        cur_setting->it_value = ktime_to_timespec(remaining);
706}
707
708/* Get the time remaining on a POSIX.1b interval timer. */
709SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
710        struct itimerspec __user *, setting)
711{
712    struct k_itimer *timr;
713    struct itimerspec cur_setting;
714    unsigned long flags;
715
716    timr = lock_timer(timer_id, &flags);
717    if (!timr)
718        return -EINVAL;
719
720    CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting));
721
722    unlock_timer(timr, flags);
723
724    if (copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
725        return -EFAULT;
726
727    return 0;
728}
729
730/*
731 * Get the number of overruns of a POSIX.1b interval timer. This is to
732 * be the overrun of the timer last delivered. At the same time we are
733 * accumulating overruns on the next timer. The overrun is frozen when
734 * the signal is delivered, either at the notify time (if the info block
735 * is not queued) or at the actual delivery time (as we are informed by
736 * the call back to do_schedule_next_timer(). So all we need to do is
737 * to pick up the frozen overrun.
738 */
739SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
740{
741    struct k_itimer *timr;
742    int overrun;
743    unsigned long flags;
744
745    timr = lock_timer(timer_id, &flags);
746    if (!timr)
747        return -EINVAL;
748
749    overrun = timr->it_overrun_last;
750    unlock_timer(timr, flags);
751
752    return overrun;
753}
754
755/* Set a POSIX.1b interval timer. */
756/* timr->it_lock is taken. */
757static int
758common_timer_set(struct k_itimer *timr, int flags,
759         struct itimerspec *new_setting, struct itimerspec *old_setting)
760{
761    struct hrtimer *timer = &timr->it.real.timer;
762    enum hrtimer_mode mode;
763
764    if (old_setting)
765        common_timer_get(timr, old_setting);
766
767    /* disable the timer */
768    timr->it.real.interval.tv64 = 0;
769    /*
770     * careful here. If smp we could be in the "fire" routine which will
771     * be spinning as we hold the lock. But this is ONLY an SMP issue.
772     */
773    if (hrtimer_try_to_cancel(timer) < 0)
774        return TIMER_RETRY;
775
776    timr->it_requeue_pending = (timr->it_requeue_pending + 2) &
777        ~REQUEUE_PENDING;
778    timr->it_overrun_last = 0;
779
780    /* switch off the timer when it_value is zero */
781    if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
782        return 0;
783
784    mode = flags & TIMER_ABSTIME ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
785    hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
786    timr->it.real.timer.function = posix_timer_fn;
787
788    hrtimer_set_expires(timer, timespec_to_ktime(new_setting->it_value));
789
790    /* Convert interval */
791    timr->it.real.interval = timespec_to_ktime(new_setting->it_interval);
792
793    /* SIGEV_NONE timers are not queued ! See common_timer_get */
794    if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
795        /* Setup correct expiry time for relative timers */
796        if (mode == HRTIMER_MODE_REL) {
797            hrtimer_add_expires(timer, timer->base->get_time());
798        }
799        return 0;
800    }
801
802    hrtimer_start_expires(timer, mode);
803    return 0;
804}
805
806/* Set a POSIX.1b interval timer */
807SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
808        const struct itimerspec __user *, new_setting,
809        struct itimerspec __user *, old_setting)
810{
811    struct k_itimer *timr;
812    struct itimerspec new_spec, old_spec;
813    int error = 0;
814    unsigned long flag;
815    struct itimerspec *rtn = old_setting ? &old_spec : NULL;
816
817    if (!new_setting)
818        return -EINVAL;
819
820    if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
821        return -EFAULT;
822
823    if (!timespec_valid(&new_spec.it_interval) ||
824        !timespec_valid(&new_spec.it_value))
825        return -EINVAL;
826retry:
827    timr = lock_timer(timer_id, &flag);
828    if (!timr)
829        return -EINVAL;
830
831    error = CLOCK_DISPATCH(timr->it_clock, timer_set,
832                   (timr, flags, &new_spec, rtn));
833
834    unlock_timer(timr, flag);
835    if (error == TIMER_RETRY) {
836        rtn = NULL; // We already got the old time...
837        goto retry;
838    }
839
840    if (old_setting && !error &&
841        copy_to_user(old_setting, &old_spec, sizeof (old_spec)))
842        error = -EFAULT;
843
844    return error;
845}
846
847static inline int common_timer_del(struct k_itimer *timer)
848{
849    timer->it.real.interval.tv64 = 0;
850
851    if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0)
852        return TIMER_RETRY;
853    return 0;
854}
855
856static inline int timer_delete_hook(struct k_itimer *timer)
857{
858    return CLOCK_DISPATCH(timer->it_clock, timer_del, (timer));
859}
860
861/* Delete a POSIX.1b interval timer. */
862SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
863{
864    struct k_itimer *timer;
865    unsigned long flags;
866
867retry_delete:
868    timer = lock_timer(timer_id, &flags);
869    if (!timer)
870        return -EINVAL;
871
872    if (timer_delete_hook(timer) == TIMER_RETRY) {
873        unlock_timer(timer, flags);
874        goto retry_delete;
875    }
876
877    spin_lock(&current->sighand->siglock);
878    list_del(&timer->list);
879    spin_unlock(&current->sighand->siglock);
880    /*
881     * This keeps any tasks waiting on the spin lock from thinking
882     * they got something (see the lock code above).
883     */
884    timer->it_signal = NULL;
885
886    unlock_timer(timer, flags);
887    release_posix_timer(timer, IT_ID_SET);
888    return 0;
889}
890
891/*
892 * return timer owned by the process, used by exit_itimers
893 */
894static void itimer_delete(struct k_itimer *timer)
895{
896    unsigned long flags;
897
898retry_delete:
899    spin_lock_irqsave(&timer->it_lock, flags);
900
901    if (timer_delete_hook(timer) == TIMER_RETRY) {
902        unlock_timer(timer, flags);
903        goto retry_delete;
904    }
905    list_del(&timer->list);
906    /*
907     * This keeps any tasks waiting on the spin lock from thinking
908     * they got something (see the lock code above).
909     */
910    timer->it_signal = NULL;
911
912    unlock_timer(timer, flags);
913    release_posix_timer(timer, IT_ID_SET);
914}
915
916/*
917 * This is called by do_exit or de_thread, only when there are no more
918 * references to the shared signal_struct.
919 */
920void exit_itimers(struct signal_struct *sig)
921{
922    struct k_itimer *tmr;
923
924    while (!list_empty(&sig->posix_timers)) {
925        tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
926        itimer_delete(tmr);
927    }
928}
929
930/* Not available / possible... functions */
931int do_posix_clock_nosettime(const clockid_t clockid, struct timespec *tp)
932{
933    return -EINVAL;
934}
935EXPORT_SYMBOL_GPL(do_posix_clock_nosettime);
936
937int do_posix_clock_nonanosleep(const clockid_t clock, int flags,
938                   struct timespec *t, struct timespec __user *r)
939{
940#ifndef ENOTSUP
941    return -EOPNOTSUPP; /* aka ENOTSUP in userland for POSIX */
942#else /* parisc does define it separately. */
943    return -ENOTSUP;
944#endif
945}
946EXPORT_SYMBOL_GPL(do_posix_clock_nonanosleep);
947
948SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
949        const struct timespec __user *, tp)
950{
951    struct timespec new_tp;
952
953    if (invalid_clockid(which_clock))
954        return -EINVAL;
955    if (copy_from_user(&new_tp, tp, sizeof (*tp)))
956        return -EFAULT;
957
958    return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp));
959}
960
961SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
962        struct timespec __user *,tp)
963{
964    struct timespec kernel_tp;
965    int error;
966
967    if (invalid_clockid(which_clock))
968        return -EINVAL;
969    error = CLOCK_DISPATCH(which_clock, clock_get,
970                   (which_clock, &kernel_tp));
971    if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
972        error = -EFAULT;
973
974    return error;
975
976}
977
978SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
979        struct timespec __user *, tp)
980{
981    struct timespec rtn_tp;
982    int error;
983
984    if (invalid_clockid(which_clock))
985        return -EINVAL;
986
987    error = CLOCK_DISPATCH(which_clock, clock_getres,
988                   (which_clock, &rtn_tp));
989
990    if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp))) {
991        error = -EFAULT;
992    }
993
994    return error;
995}
996
997/*
998 * nanosleep for monotonic and realtime clocks
999 */
1000static int common_nsleep(const clockid_t which_clock, int flags,
1001             struct timespec *tsave, struct timespec __user *rmtp)
1002{
1003    return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
1004                 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
1005                 which_clock);
1006}
1007
1008SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
1009        const struct timespec __user *, rqtp,
1010        struct timespec __user *, rmtp)
1011{
1012    struct timespec t;
1013
1014    if (invalid_clockid(which_clock))
1015        return -EINVAL;
1016
1017    if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
1018        return -EFAULT;
1019
1020    if (!timespec_valid(&t))
1021        return -EINVAL;
1022
1023    return CLOCK_DISPATCH(which_clock, nsleep,
1024                  (which_clock, flags, &t, rmtp));
1025}
1026
1027/*
1028 * nanosleep_restart for monotonic and realtime clocks
1029 */
1030static int common_nsleep_restart(struct restart_block *restart_block)
1031{
1032    return hrtimer_nanosleep_restart(restart_block);
1033}
1034
1035/*
1036 * This will restart clock_nanosleep. This is required only by
1037 * compat_clock_nanosleep_restart for now.
1038 */
1039long
1040clock_nanosleep_restart(struct restart_block *restart_block)
1041{
1042    clockid_t which_clock = restart_block->arg0;
1043
1044    return CLOCK_DISPATCH(which_clock, nsleep_restart,
1045                  (restart_block));
1046}
1047

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