posix-timers.c

linux 2.6.19 kernel source code before patching

			 &new_timer_id, sizeof (new_timer_id))) {
		error = -EFAULT;
		goto out;
	}
	if (timer_event_spec) {
		if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
			error = -EFAULT;
			goto out;
		}
		new_timer->it_sigev_notify = event.sigev_notify;
		new_timer->it_sigev_signo = event.sigev_signo;
		new_timer->it_sigev_value = event.sigev_value;

		read_lock(&tasklist_lock);
		if ((process = good_sigevent(&event))) {
			/*
			 * We may be setting up this process for another
			 * thread.  It may be exiting.  To catch this
			 * case the we check the PF_EXITING flag.  If
			 * the flag is not set, the siglock will catch
			 * him before it is too late (in exit_itimers).
			 *
			 * The exec case is a bit more invloved but easy
			 * to code.  If the process is in our thread
			 * group (and it must be or we would not allow
			 * it here) and is doing an exec, it will cause
			 * us to be killed.  In this case it will wait
			 * for us to die which means we can finish this
			 * linkage with our last gasp. I.e. no code :)
			 */
			spin_lock_irqsave(&process->sighand->siglock, flags);
			if (!(process->flags & PF_EXITING)) {
				new_timer->it_process = process;
				list_add(&new_timer->list,
					 &process->signal->posix_timers);
				spin_unlock_irqrestore(&process->sighand->siglock, flags);
				if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
					get_task_struct(process);
			} else {
				spin_unlock_irqrestore(&process->sighand->siglock, flags);
				process = NULL;
			}
		}
		read_unlock(&tasklist_lock);
		if (!process) {
			error = -EINVAL;
			goto out;
		}
	} else {
		new_timer->it_sigev_notify = SIGEV_SIGNAL;
		new_timer->it_sigev_signo = SIGALRM;
		new_timer->it_sigev_value.sival_int = new_timer->it_id;
		process = current->group_leader;
		spin_lock_irqsave(&process->sighand->siglock, flags);
		new_timer->it_process = process;
		list_add(&new_timer->list, &process->signal->posix_timers);
		spin_unlock_irqrestore(&process->sighand->siglock, flags);
	}

 	/*
	 * 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:
	if (error)
		release_posix_timer(new_timer, it_id_set);

	return error;
}

/*
 * 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;
	/*
	 * Watch out here.  We do a irqsave on the idr_lock and pass the
	 * flags part over to the timer lock.  Must not let interrupts in
	 * while we are moving the lock.
	 */

	spin_lock_irqsave(&idr_lock, *flags);
	timr = (struct k_itimer *) idr_find(&posix_timers_id, (int) timer_id);
	if (timr) {
		spin_lock(&timr->it_lock);
		spin_unlock(&idr_lock);

		if ((timr->it_id != timer_id) || !(timr->it_process) ||
				timr->it_process->tgid != current->tgid) {
			unlock_timer(timr, *flags);
			timr = NULL;
		}
	} else
		spin_unlock_irqrestore(&idr_lock, *flags);

	return timr;
}

/*
 * 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.
 */
static void
common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
{
	ktime_t now, remaining, iv;
	struct hrtimer *timer = &timr->it.real.timer;

	memset(cur_setting, 0, sizeof(struct itimerspec));

	iv = timr->it.real.interval;

	/* interval timer ? */
	if (iv.tv64)
		cur_setting->it_interval = ktime_to_timespec(iv);
	else if (!hrtimer_active(timer) &&
		 (timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
		return;

	now = timer->base->get_time();

	/*
	 * 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.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
	    (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
		timr->it_overrun += hrtimer_forward(timer, now, iv);

	remaining = ktime_sub(timer->expires, now);
	/* Return 0 only, when the timer is expired and not pending */
	if (remaining.tv64 <= 0) {
		/*
		 * A single shot SIGEV_NONE timer must return 0, when
		 * it is expired !
		 */
		if ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
			cur_setting->it_value.tv_nsec = 1;
	} else
		cur_setting->it_value = ktime_to_timespec(remaining);
}

/* Get the time remaining on a POSIX.1b interval timer. */
asmlinkage long
sys_timer_gettime(timer_t timer_id, struct itimerspec __user *setting)
{
	struct k_itimer *timr;
	struct itimerspec cur_setting;
	unsigned long flags;

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

	CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting));

	unlock_timer(timr, flags);

	if (copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
		return -EFAULT;

	return 0;
}

/*
 * 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 do_schedule_next_timer().  So all we need to do is
 * to pick up the frozen overrun.
 */
asmlinkage long
sys_timer_getoverrun(timer_t timer_id)
{
	struct k_itimer *timr;
	int overrun;
	long flags;

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

	overrun = timr->it_overrun_last;
	unlock_timer(timr, flags);

	return overrun;
}

/* Set a POSIX.1b interval timer. */
/* timr->it_lock is taken. */
static int
common_timer_set(struct k_itimer *timr, int flags,
		 struct itimerspec *new_setting, struct itimerspec *old_setting)
{
	struct hrtimer *timer = &timr->it.real.timer;
	enum hrtimer_mode mode;

	if (old_setting)
		common_timer_get(timr, old_setting);

	/* disable the timer */
	timr->it.real.interval.tv64 = 0;
	/*
	 * careful here.  If smp we could be in the "fire" routine which will
	 * be spinning as we hold the lock.  But this is ONLY an SMP issue.
	 */
	if (hrtimer_try_to_cancel(timer) < 0)
		return TIMER_RETRY;

	timr->it_requeue_pending = (timr->it_requeue_pending + 2) & 
		~REQUEUE_PENDING;
	timr->it_overrun_last = 0;

	/* switch off the timer when it_value is zero */
	if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
		return 0;

	mode = flags & TIMER_ABSTIME ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
	hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
	timr->it.real.timer.function = posix_timer_fn;

	timer->expires = timespec_to_ktime(new_setting->it_value);

	/* Convert interval */
	timr->it.real.interval = timespec_to_ktime(new_setting->it_interval);

	/* SIGEV_NONE timers are not queued ! See common_timer_get */
	if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
		/* Setup correct expiry time for relative timers */
		if (mode == HRTIMER_MODE_REL)
			timer->expires = ktime_add(timer->expires,
						   timer->base->get_time());
		return 0;
	}

	hrtimer_start(timer, timer->expires, mode);
	return 0;
}

/* Set a POSIX.1b interval timer */
asmlinkage long
sys_timer_settime(timer_t timer_id, int flags,
		  const struct itimerspec __user *new_setting,
		  struct itimerspec __user *old_setting)
{
	struct k_itimer *timr;
	struct itimerspec new_spec, old_spec;
	int error = 0;
	long flag;
	struct itimerspec *rtn = old_setting ? &old_spec : NULL;

	if (!new_setting)
		return -EINVAL;

	if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
		return -EFAULT;

	if (!timespec_valid(&new_spec.it_interval) ||
	    !timespec_valid(&new_spec.it_value))
		return -EINVAL;
retry:
	timr = lock_timer(timer_id, &flag);
	if (!timr)
		return -EINVAL;

	error = CLOCK_DISPATCH(timr->it_clock, timer_set,
			       (timr, flags, &new_spec, rtn));

	unlock_timer(timr, flag);
	if (error == TIMER_RETRY) {
		rtn = NULL;	// We already got the old time...
		goto retry;
	}

	if (old_setting && !error &&
	    copy_to_user(old_setting, &old_spec, sizeof (old_spec)))
		error = -EFAULT;

	return error;
}

static inline int common_timer_del(struct k_itimer *timer)
{
	timer->it.real.interval.tv64 = 0;

	if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0)
		return TIMER_RETRY;
	return 0;
}

static inline int timer_delete_hook(struct k_itimer *timer)
{
	return CLOCK_DISPATCH(timer->it_clock, timer_del, (timer));
}

/* Delete a POSIX.1b interval timer. */
asmlinkage long
sys_timer_delete(timer_t timer_id)
{
	struct k_itimer *timer;
	long flags;

retry_delete:
	timer = lock_timer(timer_id, &flags);
	if (!timer)
		return -EINVAL;

	if (timer_delete_hook(timer) == TIMER_RETRY) {
		unlock_timer(timer, flags);
		goto retry_delete;
	}

	spin_lock(&current->sighand->siglock);
	list_del(&timer->list);
	spin_unlock(&current->sighand->siglock);
	/*
	 * This keeps any tasks waiting on the spin lock from thinking
	 * they got something (see the lock code above).
	 */
	if (timer->it_process) {
		if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
			put_task_struct(timer->it_process);
		timer->it_process = NULL;
	}
	unlock_timer(timer, flags);
	release_posix_timer(timer, IT_ID_SET);
	return 0;
}

/*
 * return timer owned by the process, used by exit_itimers
 */
static void itimer_delete(struct k_itimer *timer)
{
	unsigned long flags;

retry_delete:
	spin_lock_irqsave(&timer->it_lock, flags);

	if (timer_delete_hook(timer) == TIMER_RETRY) {
		unlock_timer(timer, flags);
		goto retry_delete;
	}
	list_del(&timer->list);
	/*
	 * This keeps any tasks waiting on the spin lock from thinking
	 * they got something (see the lock code above).
	 */
	if (timer->it_process) {
		if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
			put_task_struct(timer->it_process);
		timer->it_process = NULL;
	}
	unlock_timer(timer, flags);
	release_posix_timer(timer, IT_ID_SET);
}

/*
 * This is called by do_exit or de_thread, only when there are no more
 * references to the shared signal_struct.
 */
void exit_itimers(struct signal_struct *sig)
{
	struct k_itimer *tmr;

	while (!list_empty(&sig->posix_timers)) {
		tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
		itimer_delete(tmr);
	}
}

/* Not available / possible... functions */
int do_posix_clock_nosettime(const clockid_t clockid, struct timespec *tp)
{
	return -EINVAL;
}
EXPORT_SYMBOL_GPL(do_posix_clock_nosettime);

int do_posix_clock_nonanosleep(const clockid_t clock, int flags,
			       struct timespec *t, struct timespec __user *r)
{
#ifndef ENOTSUP
	return -EOPNOTSUPP;	/* aka ENOTSUP in userland for POSIX */
#else  /*  parisc does define it separately.  */
	return -ENOTSUP;
#endif
}
EXPORT_SYMBOL_GPL(do_posix_clock_nonanosleep);

asmlinkage long sys_clock_settime(const clockid_t which_clock,
				  const struct timespec __user *tp)
{
	struct timespec new_tp;

	if (invalid_clockid(which_clock))
		return -EINVAL;
	if (copy_from_user(&new_tp, tp, sizeof (*tp)))
		return -EFAULT;

	return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp));
}

asmlinkage long
sys_clock_gettime(const clockid_t which_clock, struct timespec __user *tp)
{
	struct timespec kernel_tp;
	int error;

	if (invalid_clockid(which_clock))
		return -EINVAL;
	error = CLOCK_DISPATCH(which_clock, clock_get,
			       (which_clock, &kernel_tp));
	if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
		error = -EFAULT;

	return error;

}

asmlinkage long
sys_clock_getres(const clockid_t which_clock, struct timespec __user *tp)
{
	struct timespec rtn_tp;
	int error;

	if (invalid_clockid(which_clock))
		return -EINVAL;

	error = CLOCK_DISPATCH(which_clock, clock_getres,
			       (which_clock, &rtn_tp));

	if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp))) {
		error = -EFAULT;
	}

	return error;
}

/*
 * nanosleep for monotonic and realtime clocks
 */
static int common_nsleep(const clockid_t which_clock, int flags,
			 struct timespec *tsave, struct timespec __user *rmtp)
{
	return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
				 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
				 which_clock);
}

asmlinkage long
sys_clock_nanosleep(const clockid_t which_clock, int flags,
		    const struct timespec __user *rqtp,
		    struct timespec __user *rmtp)
{
	struct timespec t;

	if (invalid_clockid(which_clock))
		return -EINVAL;

	if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
		return -EFAULT;

	if (!timespec_valid(&t))
		return -EINVAL;

	return CLOCK_DISPATCH(which_clock, nsleep,
			      (which_clock, flags, &t, rmtp));
}

/*
 * nanosleep_restart for monotonic and realtime clocks
 */
static int common_nsleep_restart(struct restart_block *restart_block)
{
	return hrtimer_nanosleep_restart(restart_block);
}

/*
 * This will restart clock_nanosleep. This is required only by
 * compat_clock_nanosleep_restart for now.
 */
long
clock_nanosleep_restart(struct restart_block *restart_block)
{
	clockid_t which_clock = restart_block->arg0;

	return CLOCK_DISPATCH(which_clock, nsleep_restart,
			      (restart_block));
}