Release 4.15 kernel/time/posix-timers.c

/*
 * linux/kernel/posix-timers.c
 *
 *
 * 2002-10-15  Posix Clocks & timers
 *                           by George Anzinger george@mvista.com
 *
 *                           Copyright (C) 2002 2003 by MontaVista Software.
 *
 * 2004-06-01  Fix CLOCK_REALTIME clock/timer TIMER_ABSTIME bug.
 *                           Copyright (C) 2004 Boris Hu
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * MontaVista Software | 1237 East Arques Avenue | Sunnyvale | CA 94085 | USA
 */

/* These are all the functions necessary to implement
 * POSIX clocks & timers
 */
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/mutex.h>
#include <linux/sched/task.h>

#include <linux/uaccess.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/compiler.h>
#include <linux/hash.h>
#include <linux/posix-clock.h>
#include <linux/posix-timers.h>
#include <linux/syscalls.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <linux/export.h>
#include <linux/hashtable.h>
#include <linux/compat.h>

#include "timekeeping.h"
#include "posix-timers.h"

/*
 * Management arrays for POSIX timers. Timers are now kept in static hash table
 * with 512 entries.
 * Timer ids are allocated by local routine, which selects proper hash head by
 * key, constructed from current->signal address and per signal struct counter.
 * This keeps timer ids unique per process, but now they can intersect between
 * processes.
 */

/*
 * Lets keep our timers in a slab cache :-)
 */

static struct kmem_cache *posix_timers_cache;

static DEFINE_HASHTABLE(posix_timers_hashtable, 9);
static DEFINE_SPINLOCK(hash_lock);


static const struct k_clock * const posix_clocks[];
static const struct k_clock *clockid_to_kclock(const clockid_t id);


static const struct k_clock clock_realtime, clock_monotonic;

/*
 * we assume that the new SIGEV_THREAD_ID shares no bits with the other
 * SIGEV values.  Here we put out an error if this assumption fails.
 */
#if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
                       ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
#error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
#endif

/*
 * parisc wants ENOTSUP instead of EOPNOTSUPP
 */
#ifndef ENOTSUP

# define ENANOSLEEP_NOTSUP EOPNOTSUPP
#else

# define ENANOSLEEP_NOTSUP ENOTSUP
#endif

/*
 * The timer ID is turned into a timer address by idr_find().
 * Verifying a valid ID consists of:
 *
 * a) checking that idr_find() returns other than -1.
 * b) checking that the timer id matches the one in the timer itself.
 * c) that the timer owner is in the callers thread group.
 */

/*
 * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
 *          to implement others.  This structure defines the various
 *          clocks.
 *
 * RESOLUTION: Clock resolution is used to round up timer and interval
 *          times, NOT to report clock times, which are reported with as
 *          much resolution as the system can muster.  In some cases this
 *          resolution may depend on the underlying clock hardware and
 *          may not be quantifiable until run time, and only then is the
 *          necessary code is written.  The standard says we should say
 *          something about this issue in the documentation...
 *
 * FUNCTIONS: The CLOCKs structure defines possible functions to
 *          handle various clock functions.
 *
 *          The standard POSIX timer management code assumes the
 *          following: 1.) The k_itimer struct (sched.h) is used for
 *          the timer.  2.) The list, it_lock, it_clock, it_id and
 *          it_pid fields are not modified by timer code.
 *
 * Permissions: It is assumed that the clock_settime() function defined
 *          for each clock will take care of permission checks.  Some
 *          clocks may be set able by any user (i.e. local process
 *          clocks) others not.  Currently the only set able clock we
 *          have is CLOCK_REALTIME and its high res counter part, both of
 *          which we beg off on and pass to do_sys_settimeofday().
 */
static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);


#define lock_timer(tid, flags)						   \
({      struct k_itimer *__timr;                                           \
        __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags));  \
        __timr;                                                            \
})



static int hash(struct signal_struct *sig, unsigned int nr)
{
	return hash_32(hash32_ptr(sig) ^ nr, HASH_BITS(posix_timers_hashtable));
}

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static struct k_itimer *__posix_timers_find(struct hlist_head *head,
					    struct signal_struct *sig,
					    timer_t id)
{
	struct k_itimer *timer;

	hlist_for_each_entry_rcu(timer, head, t_hash) {
		if ((timer->it_signal == sig) && (timer->it_id == id))
			return timer;
	}
	return NULL;
}

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static struct k_itimer *posix_timer_by_id(timer_t id)
{
	struct signal_struct *sig = current->signal;
	struct hlist_head *head = &posix_timers_hashtable[hash(sig, id)];

	return __posix_timers_find(head, sig, id);
}

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static int posix_timer_add(struct k_itimer *timer)
{
	struct signal_struct *sig = current->signal;
	int first_free_id = sig->posix_timer_id;
	struct hlist_head *head;
	int ret = -ENOENT;

	do {
		spin_lock(&hash_lock);
		head = &posix_timers_hashtable[hash(sig, sig->posix_timer_id)];
		if (!__posix_timers_find(head, sig, sig->posix_timer_id)) {
			hlist_add_head_rcu(&timer->t_hash, head);
			ret = sig->posix_timer_id;
		}
		if (++sig->posix_timer_id < 0)
			sig->posix_timer_id = 0;
		if ((sig->posix_timer_id == first_free_id) && (ret == -ENOENT))
			/* Loop over all possible ids completed */
			ret = -EAGAIN;
		spin_unlock(&hash_lock);
	} while (ret == -ENOENT);
	return ret;
}

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static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
{
	spin_unlock_irqrestore(&timr->it_lock, flags);
}

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/* Get clock_realtime */


static int posix_clock_realtime_get(clockid_t which_clock, struct timespec64 *tp)
{
	ktime_get_real_ts64(tp);
	return 0;
}

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/* Set clock_realtime */


static int posix_clock_realtime_set(const clockid_t which_clock,
				    const struct timespec64 *tp)
{
	return do_sys_settimeofday64(tp, NULL);
}

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static int posix_clock_realtime_adj(const clockid_t which_clock,
				    struct timex *t)
{
	return do_adjtimex(t);
}

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/*
 * Get monotonic time for posix timers
 */


static int posix_ktime_get_ts(clockid_t which_clock, struct timespec64 *tp)
{
	ktime_get_ts64(tp);
	return 0;
}

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/*
 * Get monotonic-raw time for posix timers
 */


static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec64 *tp)
{
	getrawmonotonic64(tp);
	return 0;
}


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static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec64 *tp)
{
	*tp = current_kernel_time64();
	return 0;
}

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static int posix_get_monotonic_coarse(clockid_t which_clock,
						struct timespec64 *tp)
{
	*tp = get_monotonic_coarse64();
	return 0;
}

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static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *tp)
{
	*tp = ktime_to_timespec64(KTIME_LOW_RES);
	return 0;
}

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static int posix_get_boottime(const clockid_t which_clock, struct timespec64 *tp)
{
	get_monotonic_boottime64(tp);
	return 0;
}

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static int posix_get_tai(clockid_t which_clock, struct timespec64 *tp)
{
	timekeeping_clocktai64(tp);
	return 0;
}

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static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
{
	tp->tv_sec = 0;
	tp->tv_nsec = hrtimer_resolution;
	return 0;
}

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/*
 * Initialize everything, well, just everything in Posix clocks/timers ;)
 */


static __init int init_posix_timers(void)
{
	posix_timers_cache = kmem_cache_create("posix_timers_cache",
					sizeof (struct k_itimer), 0, SLAB_PANIC,
					NULL);
	return 0;
}
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__initcall(init_posix_timers);



static void common_hrtimer_rearm(struct k_itimer *timr)
{
	struct hrtimer *timer = &timr->it.real.timer;

	if (!timr->it_interval)
		return;

	timr->it_overrun += (unsigned int) hrtimer_forward(timer,
						timer->base->get_time(),
						timr->it_interval);
	hrtimer_restart(timer);
}

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/*
 * This function is exported for use by the signal deliver code.  It is
 * called just prior to the info block being released and passes that
 * block to us.  It's function is to update the overrun entry AND to
 * restart the timer.  It should only be called if the timer is to be
 * restarted (i.e. we have flagged this in the sys_private entry of the
 * info block).
 *
 * To protect against the timer going away while the interrupt is queued,
 * we require that the it_requeue_pending flag be set.
 */


void posixtimer_rearm(struct siginfo *info)
{
	struct k_itimer *timr;
	unsigned long flags;

	timr = lock_timer(info->si_tid, &flags);
	if (!timr)
		return;

	if (timr->it_requeue_pending == info->si_sys_private) {
		timr->kclock->timer_rearm(timr);

		timr->it_active = 1;
		timr->it_overrun_last = timr->it_overrun;
		timr->it_overrun = -1;
		++timr->it_requeue_pending;

		info->si_overrun += timr->it_overrun_last;
	}

	unlock_timer(timr, flags);
}

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int posix_timer_event(struct k_itimer *timr, int si_private)
{
	struct task_struct *task;
	int shared, ret = -1;
	/*
         * FIXME: if ->sigq is queued we can race with
         * dequeue_signal()->posixtimer_rearm().
         *
         * If dequeue_signal() sees the "right" value of
         * si_sys_private it calls posixtimer_rearm().
         * We re-queue ->sigq and drop ->it_lock().
         * posixtimer_rearm() locks the timer
         * and re-schedules it while ->sigq is pending.
         * Not really bad, but not that we want.
         */
	timr->sigq->info.si_sys_private = si_private;

	rcu_read_lock();
	task = pid_task(timr->it_pid, PIDTYPE_PID);
	if (task) {
		shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
		ret = send_sigqueue(timr->sigq, task, shared);
	}
	rcu_read_unlock();
	/* If we failed to send the signal the timer stops. */
	return ret > 0;
}

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/*
 * This function gets called when a POSIX.1b interval timer expires.  It
 * is used as a callback from the kernel internal timer.  The
 * run_timer_list code ALWAYS calls with interrupts on.

 * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
 */


static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
{
	struct k_itimer *timr;
	unsigned long flags;
	int si_private = 0;
	enum hrtimer_restart ret = HRTIMER_NORESTART;

	timr = container_of(timer, struct k_itimer, it.real.timer);
	spin_lock_irqsave(&timr->it_lock, flags);

	timr->it_active = 0;
	if (timr->it_interval != 0)
		si_private = ++timr->it_requeue_pending;

	if (posix_timer_event(timr, si_private)) {
		/*
                 * signal was not sent because of sig_ignor
                 * we will not get a call back to restart it AND
                 * it should be restarted.
                 */
		if (timr->it_interval != 0) {
			ktime_t now = hrtimer_cb_get_time(timer);

			/*
                         * FIXME: What we really want, is to stop this
                         * timer completely and restart it in case the
                         * SIG_IGN is removed. This is a non trivial
                         * change which involves sighand locking
                         * (sigh !), which we don't want to do late in
                         * the release cycle.
                         *
                         * For now we just let timers with an interval
                         * less than a jiffie expire every jiffie to
                         * avoid softirq starvation in case of SIG_IGN
                         * and a very small interval, which would put
                         * the timer right back on the softirq pending
                         * list. By moving now ahead of time we trick
                         * hrtimer_forward() to expire the timer
                         * later, while we still maintain the overrun
                         * accuracy, but have some inconsistency in
                         * the timer_gettime() case. This is at least
                         * better than a starved softirq. A more
                         * complex fix which solves also another related
                         * inconsistency is already in the pipeline.
                         */
#ifdef CONFIG_HIGH_RES_TIMERS
			{
				ktime_t kj = NSEC_PER_SEC / HZ;

				if (timr->it_interval < kj)
					now = ktime_add(now, kj);
			}
#endif
			timr->it_overrun += (unsigned int)
				hrtimer_forward(timer, now,
						timr->it_interval);
			ret = HRTIMER_RESTART;
			++timr->it_requeue_pending;
			timr->it_active = 1;
		}
	}

	unlock_timer(timr, flags);
	return ret;
}

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static struct pid *good_sigevent(sigevent_t * event)
{
	struct task_struct *rtn = current->group_leader;

	switch (event->sigev_notify) {
	case SIGEV_SIGNAL | SIGEV_THREAD_ID:
		rtn = find_task_by_vpid(event->sigev_notify_thread_id);
		if (!rtn || !same_thread_group(rtn, current))
			return NULL;
		/* FALLTHRU */
	case SIGEV_SIGNAL:
	case SIGEV_THREAD:
		if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
			return NULL;
		/* FALLTHRU */
	case SIGEV_NONE:
		return task_pid(rtn);
	default:
		return NULL;
	}
}

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static struct k_itimer * alloc_posix_timer(void)
{
	struct k_itimer *tmr;
	tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
	if (!tmr)
		return tmr;
	if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
		kmem_cache_free(posix_timers_cache, tmr);
		return NULL;
	}
	memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
	return tmr;
}

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static void k_itimer_rcu_free(struct rcu_head *head)
{
	struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu);

	kmem_cache_free(posix_timers_cache, tmr);
}

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#define IT_ID_SET	1

#define IT_ID_NOT_SET	0


static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
{
	if (it_id_set) {
		unsigned long flags;
		spin_lock_irqsave(&hash_lock, flags);
		hlist_del_rcu(&tmr->t_hash);
		spin_unlock_irqrestore(&hash_lock, flags);
	}
	put_pid(tmr->it_pid);
	sigqueue_free(tmr->sigq);
	call_rcu(&tmr->it.rcu, k_itimer_rcu_free);
}

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static int common_timer_create(struct k_itimer *new_timer)
{
	hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
	return 0;
}

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/* Create a POSIX.1b interval timer. */


static int do_timer_create(clockid_t which_clock, struct sigevent *event,
			   timer_t __user *created_timer_id)
{
	const struct k_clock *kc = clockid_to_kclock(which_clock);
	struct k_itimer *new_timer;
	int error, new_timer_id;
	int it_id_set = IT_ID_NOT_SET;

	if (!kc)
		return -EINVAL;
	if (!kc->timer_create)
		return -EOPNOTSUPP;

	new_timer = alloc_posix_timer();
	if (unlikely(!new_timer))
		return -EAGAIN;

	spin_lock_init(&new_timer->it_lock);
	new_timer_id = posix_timer_add(new_timer);
	if (new_timer_id < 0) {
		error = new_timer_id;
		goto out;
	}

	it_id_set = IT_ID_SET;
	new_timer->it_id = (timer_t) new_timer_id;
	new_timer->it_clock = which_clock;
	new_timer->kclock = kc;
	new_timer->it_overrun = -1;

	if (event) {
		rcu_read_lock();
		new_timer->it_pid = get_pid(good_sigevent(event));
		rcu_read_unlock();
		if (!new_timer->it_pid) {
			error = -EINVAL;
			goto out;
		}
		new_timer->it_sigev_notify     = event->sigev_notify;
		new_timer->sigq->info.si_signo = event->sigev_signo;
		new_timer->sigq->info.si_value = event->sigev_value;
	} else {
		new_timer->it_sigev_notify     = SIGEV_SIGNAL;
		new_timer->sigq->info.si_signo = SIGALRM;
		memset(&new_timer->sigq->info.si_value, 0, sizeof(sigval_t));
		new_timer->sigq->info.si_value.sival_int = new_timer->it_id;
		new_timer->it_pid = get_pid(task_tgid(current));
	}

	new_timer->sigq->info.si_tid   = new_timer->it_id;
	new_timer->sigq->info.si_code  = SI_TIMER;

	if (copy_to_user(created_timer_id,
			 &new_timer_id, sizeof (new_timer_id))) {
		error = -EFAULT;
		goto out;
	}

	error = kc->timer_create(new_timer);
	if (error)
		goto out;

	spin_lock_irq(&current->sighand->siglock);
	new_timer->it_signal = current->signal;
	list_add(&new_timer->list, &current->signal->posix_timers);
	spin_unlock_irq(&current->sighand->siglock);

	return 0;
	/*
         * In the case of the timer belonging to another task, after
         * the task is unlocked, the timer is owned by the other task
         * and may cease to exist at any time.  Don't use or modify
         * new_timer after the unlock call.
         */
out:
	release_posix_timer(new_timer, it_id_set);
	return error;
}

Contributors
Person
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CommitProp
Thomas Gleixner
126
31.27%
4
18.18%
Al Viro
77
19.11%
1
4.55%
Oleg Nesterov
72
17.87%
8
36.36%
George Anzinger
50
12.41%
1
4.55%
Andrey Vagin
38
9.43%
2
9.09%
Andrew Morton
19
4.71%
2
9.09%
Jim Houston
9
2.23%
1
4.55%
Corey Minyard
7
1.74%
1
4.55%
Eric Dumazet
3
0.74%
1
4.55%
Dan Carpenter
2
0.50%
1
4.55%
Total
403
100.00%
22
100.00%


SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
		struct sigevent __user *, timer_event_spec,
		timer_t __user *, created_timer_id)
{
	if (timer_event_spec) {
		sigevent_t event;

		if (copy_from_user(&event, timer_event_spec, sizeof (event)))
			return -EFAULT;
		return do_timer_create(which_clock, &event, created_timer_id);
	}
	return do_timer_create(which_clock, NULL, created_timer_id);
}

#ifdef CONFIG_COMPAT

COMPAT_SYSCALL_DEFINE3(timer_create, clockid_t, which_clock,
		       struct compat_sigevent __user *, timer_event_spec,
		       timer_t __user *, created_timer_id)
{
	if (timer_event_spec) {
		sigevent_t event;

		if (get_compat_sigevent(&event, timer_event_spec))
			return -EFAULT;
		return do_timer_create(which_clock, &event, created_timer_id);
	}
	return do_timer_create(which_clock, NULL, created_timer_id);
}
#endif

/*
 * Locking issues: We need to protect the result of the id look up until
 * we get the timer locked down so it is not deleted under us.  The
 * removal is done under the idr spinlock so we use that here to bridge
 * the find to the timer lock.  To avoid a dead lock, the timer id MUST
 * be release with out holding the timer lock.
 */


static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
{
	struct k_itimer *timr;

	/*
         * timer_t could be any type >= int and we want to make sure any
         * @timer_id outside positive int range fails lookup.
         */
	if ((unsigned long long)timer_id > INT_MAX)
		return NULL;

	rcu_read_lock();
	timr = posix_timer_by_id(timer_id);
	if (timr) {
		spin_lock_irqsave(&timr->it_lock, *flags);
		if (timr->it_signal == current->signal) {
			rcu_read_unlock();
			return timr;
		}
		spin_unlock_irqrestore(&timr->it_lock, *flags);
	}
	rcu_read_unlock();

	return NULL;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
George Anzinger
55
56.12%
1
11.11%
Tejun Heo
15
15.31%
1
11.11%
Eric Dumazet
13
13.27%
1
11.11%
Oleg Nesterov
10
10.20%
2
22.22%
Thomas Gleixner
2
2.04%
1
11.11%
Pavel Emelyanov
1
1.02%
1
11.11%
Andi Kleen
1
1.02%
1
11.11%
Namhyung Kim
1
1.02%
1
11.11%
Total
98
100.00%
9
100.00%



static ktime_t common_hrtimer_remaining(struct k_itimer *timr, ktime_t now)
{
	struct hrtimer *timer = &timr->it.real.timer;

	return __hrtimer_expires_remaining_adjusted(timer, now);
}

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Thomas Gleixner
36
100.00%
1
100.00%
Total
36
100.00%
1
100.00%



static int common_hrtimer_forward(struct k_itimer *timr, ktime_t now)
{
	struct hrtimer *timer = &timr->it.real.timer;

	return (int)hrtimer_forward(timer, now, timr->it_interval);
}

Contributors
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CommitProp
Thomas Gleixner
43
100.00%
1
100.00%
Total
43
100.00%
1
100.00%

/*
 * Get the time remaining on a POSIX.1b interval timer.  This function
 * is ALWAYS called with spin_lock_irq on the timer, thus it must not
 * mess with irq.
 *
 * We have a couple of messes to clean up here.  First there is the case
 * of a timer that has a requeue pending.  These timers should appear to
 * be in the timer list with an expiry as if we were to requeue them
 * now.
 *
 * The second issue is the SIGEV_NONE timer which may be active but is
 * not really ever put in the timer list (to save system resources).
 * This timer may be expired, and if so, we will do it here.  Otherwise
 * it is the same as a requeue pending timer WRT to what we should
 * report.
 */


void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
{
	const struct k_clock *kc = timr->kclock;
	ktime_t now, remaining, iv;
	struct timespec64 ts64;
	bool sig_none;

	sig_none = timr->it_sigev_notify == SIGEV_NONE;
	iv = timr->it_interval;

	/* interval timer ? */
	if (iv) {
		cur_setting->it_interval = ktime_to_timespec64(iv);
	} else if (!timr->it_active) {
		/*
                 * SIGEV_NONE oneshot timers are never queued. Check them
                 * below.
                 */
		if (!sig_none)
			return;
	}

	/*
         * The timespec64 based conversion is suboptimal, but it's not
         * worth to implement yet another callback.
         */
	kc->clock_get(timr->it_clock, &ts64);
	now = timespec64_to_ktime(ts64);

	/*
         * When a requeue is pending or this is a SIGEV_NONE timer move the
         * expiry time forward by intervals, so expiry is > now.
         */
	if (iv && (timr->it_requeue_pending & REQUEUE_PENDING || sig_none))
		timr->it_overrun += kc->timer_forward(timr, now);

	remaining = kc->timer_remaining(timr, now);
	/* Return 0 only, when the timer is expired and not pending */
	if (remaining <= 0) {
		/*
                 * A single shot SIGEV_NONE timer must return 0, when
                 * it is expired !
                 */
		if (!sig_none)
			cur_setting->it_value.tv_nsec = 1;
	} else {
		cur_setting->it_value = ktime_to_timespec64(remaining);
	}
}

Contributors
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Tokens
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CommitProp
Thomas Gleixner
89
49.44%
5
45.45%
George Anzinger
52
28.89%
2
18.18%
Roman Zippel
34
18.89%
1
9.09%
Deepa Dinamani
3
1.67%
1
9.09%
Roland McGrath
1
0.56%
1
9.09%
Arjan van de Ven
1
0.56%
1
9.09%
Total
180
100.00%
11
100.00%

/* Get the time remaining on a POSIX.1b interval timer. */


static int do_timer_gettime(timer_t timer_id,  struct itimerspec64 *setting)
{
	struct k_itimer *timr;
	const struct k_clock *kc;
	unsigned long flags;
	int ret = 0;

	timr = lock_timer(timer_id, &flags);
	if (!timr)
		return -EINVAL;

	memset(setting, 0, sizeof(*setting));
	kc = timr->kclock;
	if (WARN_ON_ONCE(!kc || !kc->timer_get))
		ret = -EINVAL;
	else
		kc->timer_get(timr, setting);

	unlock_timer(timr, flags);
	return ret;
}

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CommitProp
Thomas Gleixner
49
44.55%
4
36.36%
George Anzinger
37
33.64%
2
18.18%
Al Viro
19
17.27%
1
9.09%
Roland McGrath
2
1.82%
1
9.09%
Deepa Dinamani
1
0.91%
1
9.09%
Andi Kleen
1
0.91%
1
9.09%
Christoph Hellwig
1
0.91%
1
9.09%
Total
110
100.00%
11
100.00%

/* Get the time remaining on a POSIX.1b interval timer. */

SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
		struct itimerspec __user *, setting)
{
	struct itimerspec64 cur_setting;

	int ret = do_timer_gettime(timer_id, &cur_setting);
	if (!ret) {
		if (put_itimerspec64(&cur_setting, setting))
			ret = -EFAULT;
	}
	return ret;
}

#ifdef CONFIG_COMPAT

COMPAT_SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
		       struct compat_itimerspec __user *, setting)
{
	struct itimerspec64 cur_setting;

	int ret = do_timer_gettime(timer_id, &cur_setting);
	if (!ret) {
		if (put_compat_itimerspec64(&cur_setting, setting))
			ret = -EFAULT;
	}
	return ret;
}
#endif

/*
 * Get the number of overruns of a POSIX.1b interval timer.  This is to
 * be the overrun of the timer last delivered.  At the same time we are
 * accumulating overruns on the next timer.  The overrun is frozen when
 * the signal is delivered, either at the notify time (if the info block
 * is not queued) or at the actual delivery time (as we are informed by
 * the call back to posixtimer_rearm().  So all we need to do is
 * to pick up the frozen overrun.
 */

SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
{