ALSA: timer: Call notifier in the same spinlock
snd_timer_notify1() is called outside the spinlock and it retakes the lock after the unlock. This is rather racy, and it's safer to move snd_timer_notify() call inside the main spinlock. The patch also contains a slight refactoring / cleanup of the code. Now all start/stop/continue/pause look more symmetric and a bit better readable. Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai
Родитель
9984d1b583
Коммит
f65e0d2998
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@ -305,8 +305,6 @@ int snd_timer_open(struct snd_timer_instance **ti,
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return 0;
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}
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static int _snd_timer_stop(struct snd_timer_instance *timeri, int event);
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/*
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* close a timer instance
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*/
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@ -389,7 +387,6 @@ unsigned long snd_timer_resolution(struct snd_timer_instance *timeri)
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static void snd_timer_notify1(struct snd_timer_instance *ti, int event)
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{
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struct snd_timer *timer;
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unsigned long flags;
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unsigned long resolution = 0;
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struct snd_timer_instance *ts;
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struct timespec tstamp;
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@ -413,34 +410,66 @@ static void snd_timer_notify1(struct snd_timer_instance *ti, int event)
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return;
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if (timer->hw.flags & SNDRV_TIMER_HW_SLAVE)
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return;
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spin_lock_irqsave(&timer->lock, flags);
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list_for_each_entry(ts, &ti->slave_active_head, active_list)
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if (ts->ccallback)
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ts->ccallback(ts, event + 100, &tstamp, resolution);
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spin_unlock_irqrestore(&timer->lock, flags);
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}
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static int snd_timer_start1(struct snd_timer *timer, struct snd_timer_instance *timeri,
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unsigned long sticks)
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/* start/continue a master timer */
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static int snd_timer_start1(struct snd_timer_instance *timeri,
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bool start, unsigned long ticks)
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{
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struct snd_timer *timer;
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int result;
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unsigned long flags;
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timer = timeri->timer;
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if (!timer)
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return -EINVAL;
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spin_lock_irqsave(&timer->lock, flags);
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if (timer->card && timer->card->shutdown) {
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result = -ENODEV;
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goto unlock;
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}
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if (timeri->flags & (SNDRV_TIMER_IFLG_RUNNING |
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SNDRV_TIMER_IFLG_START)) {
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result = -EBUSY;
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goto unlock;
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}
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if (start)
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timeri->ticks = timeri->cticks = ticks;
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else if (!timeri->cticks)
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timeri->cticks = 1;
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timeri->pticks = 0;
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list_move_tail(&timeri->active_list, &timer->active_list_head);
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if (timer->running) {
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if (timer->hw.flags & SNDRV_TIMER_HW_SLAVE)
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goto __start_now;
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timer->flags |= SNDRV_TIMER_FLG_RESCHED;
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timeri->flags |= SNDRV_TIMER_IFLG_START;
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return 1; /* delayed start */
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result = 1; /* delayed start */
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} else {
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timer->sticks = sticks;
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if (start)
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timer->sticks = ticks;
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timer->hw.start(timer);
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__start_now:
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timer->running++;
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timeri->flags |= SNDRV_TIMER_IFLG_RUNNING;
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return 0;
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result = 0;
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}
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snd_timer_notify1(timeri, start ? SNDRV_TIMER_EVENT_START :
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SNDRV_TIMER_EVENT_CONTINUE);
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unlock:
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spin_unlock_irqrestore(&timer->lock, flags);
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return result;
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}
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static int snd_timer_start_slave(struct snd_timer_instance *timeri)
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/* start/continue a slave timer */
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static int snd_timer_start_slave(struct snd_timer_instance *timeri,
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bool start)
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{
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unsigned long flags;
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@ -454,88 +483,37 @@ static int snd_timer_start_slave(struct snd_timer_instance *timeri)
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spin_lock(&timeri->timer->lock);
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list_add_tail(&timeri->active_list,
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&timeri->master->slave_active_head);
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snd_timer_notify1(timeri, start ? SNDRV_TIMER_EVENT_START :
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SNDRV_TIMER_EVENT_CONTINUE);
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spin_unlock(&timeri->timer->lock);
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}
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spin_unlock_irqrestore(&slave_active_lock, flags);
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return 1; /* delayed start */
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}
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/*
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* start the timer instance
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*/
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int snd_timer_start(struct snd_timer_instance *timeri, unsigned int ticks)
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/* stop/pause a master timer */
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static int snd_timer_stop1(struct snd_timer_instance *timeri, bool stop)
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{
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struct snd_timer *timer;
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int result = -EINVAL;
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int result = 0;
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unsigned long flags;
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if (timeri == NULL || ticks < 1)
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return -EINVAL;
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if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE) {
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result = snd_timer_start_slave(timeri);
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if (result >= 0)
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snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_START);
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return result;
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}
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timer = timeri->timer;
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if (timer == NULL)
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return -EINVAL;
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if (timer->card && timer->card->shutdown)
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return -ENODEV;
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spin_lock_irqsave(&timer->lock, flags);
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if (timeri->flags & (SNDRV_TIMER_IFLG_RUNNING |
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SNDRV_TIMER_IFLG_START)) {
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result = -EBUSY;
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goto unlock;
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}
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timeri->ticks = timeri->cticks = ticks;
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timeri->pticks = 0;
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result = snd_timer_start1(timer, timeri, ticks);
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unlock:
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spin_unlock_irqrestore(&timer->lock, flags);
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if (result >= 0)
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snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_START);
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return result;
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}
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static int _snd_timer_stop(struct snd_timer_instance *timeri, int event)
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{
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struct snd_timer *timer;
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unsigned long flags;
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if (snd_BUG_ON(!timeri))
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return -ENXIO;
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if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE) {
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spin_lock_irqsave(&slave_active_lock, flags);
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if (!(timeri->flags & SNDRV_TIMER_IFLG_RUNNING)) {
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spin_unlock_irqrestore(&slave_active_lock, flags);
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return -EBUSY;
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}
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if (timeri->timer)
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spin_lock(&timeri->timer->lock);
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timeri->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
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list_del_init(&timeri->ack_list);
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list_del_init(&timeri->active_list);
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if (timeri->timer)
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spin_unlock(&timeri->timer->lock);
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spin_unlock_irqrestore(&slave_active_lock, flags);
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goto __end;
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}
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timer = timeri->timer;
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if (!timer)
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return -EINVAL;
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spin_lock_irqsave(&timer->lock, flags);
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if (!(timeri->flags & (SNDRV_TIMER_IFLG_RUNNING |
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SNDRV_TIMER_IFLG_START))) {
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spin_unlock_irqrestore(&timer->lock, flags);
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return -EBUSY;
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result = -EBUSY;
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goto unlock;
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}
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list_del_init(&timeri->ack_list);
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list_del_init(&timeri->active_list);
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if (timer->card && timer->card->shutdown) {
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spin_unlock_irqrestore(&timer->lock, flags);
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return 0;
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if (timer->card && timer->card->shutdown)
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goto unlock;
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if (stop) {
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timeri->cticks = timeri->ticks;
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timeri->pticks = 0;
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}
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if ((timeri->flags & SNDRV_TIMER_IFLG_RUNNING) &&
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!(--timer->running)) {
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@ -550,13 +528,49 @@ static int _snd_timer_stop(struct snd_timer_instance *timeri, int event)
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}
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}
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timeri->flags &= ~(SNDRV_TIMER_IFLG_RUNNING | SNDRV_TIMER_IFLG_START);
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snd_timer_notify1(timeri, stop ? SNDRV_TIMER_EVENT_STOP :
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SNDRV_TIMER_EVENT_CONTINUE);
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unlock:
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spin_unlock_irqrestore(&timer->lock, flags);
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__end:
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if (event != SNDRV_TIMER_EVENT_RESOLUTION)
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snd_timer_notify1(timeri, event);
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return result;
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}
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/* stop/pause a slave timer */
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static int snd_timer_stop_slave(struct snd_timer_instance *timeri, bool stop)
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{
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unsigned long flags;
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spin_lock_irqsave(&slave_active_lock, flags);
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if (!(timeri->flags & SNDRV_TIMER_IFLG_RUNNING)) {
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spin_unlock_irqrestore(&slave_active_lock, flags);
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return -EBUSY;
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}
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timeri->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
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if (timeri->timer) {
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spin_lock(&timeri->timer->lock);
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list_del_init(&timeri->ack_list);
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list_del_init(&timeri->active_list);
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snd_timer_notify1(timeri, stop ? SNDRV_TIMER_EVENT_STOP :
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SNDRV_TIMER_EVENT_CONTINUE);
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spin_unlock(&timeri->timer->lock);
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}
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spin_unlock_irqrestore(&slave_active_lock, flags);
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return 0;
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}
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/*
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* start the timer instance
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*/
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int snd_timer_start(struct snd_timer_instance *timeri, unsigned int ticks)
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{
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if (timeri == NULL || ticks < 1)
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return -EINVAL;
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if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
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return snd_timer_start_slave(timeri, true);
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else
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return snd_timer_start1(timeri, true, ticks);
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}
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/*
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* stop the timer instance.
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*
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@ -564,21 +578,10 @@ static int _snd_timer_stop(struct snd_timer_instance *timeri, int event)
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*/
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int snd_timer_stop(struct snd_timer_instance *timeri)
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{
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struct snd_timer *timer;
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unsigned long flags;
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int err;
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err = _snd_timer_stop(timeri, SNDRV_TIMER_EVENT_STOP);
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if (err < 0)
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return err;
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timer = timeri->timer;
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if (!timer)
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return -EINVAL;
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spin_lock_irqsave(&timer->lock, flags);
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timeri->cticks = timeri->ticks;
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timeri->pticks = 0;
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spin_unlock_irqrestore(&timer->lock, flags);
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return 0;
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if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
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return snd_timer_stop_slave(timeri, true);
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else
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return snd_timer_stop1(timeri, true);
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}
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/*
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@ -586,32 +589,10 @@ int snd_timer_stop(struct snd_timer_instance *timeri)
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*/
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int snd_timer_continue(struct snd_timer_instance *timeri)
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{
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struct snd_timer *timer;
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int result = -EINVAL;
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unsigned long flags;
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if (timeri == NULL)
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return result;
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if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
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return snd_timer_start_slave(timeri);
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timer = timeri->timer;
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if (! timer)
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return -EINVAL;
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if (timer->card && timer->card->shutdown)
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return -ENODEV;
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spin_lock_irqsave(&timer->lock, flags);
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if (timeri->flags & SNDRV_TIMER_IFLG_RUNNING) {
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result = -EBUSY;
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goto unlock;
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}
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if (!timeri->cticks)
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timeri->cticks = 1;
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timeri->pticks = 0;
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result = snd_timer_start1(timer, timeri, timer->sticks);
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unlock:
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spin_unlock_irqrestore(&timer->lock, flags);
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snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_CONTINUE);
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return result;
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return snd_timer_start_slave(timeri, false);
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else
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return snd_timer_start1(timeri, false, 0);
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}
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/*
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@ -619,7 +600,10 @@ int snd_timer_continue(struct snd_timer_instance *timeri)
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*/
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int snd_timer_pause(struct snd_timer_instance * timeri)
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{
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return _snd_timer_stop(timeri, SNDRV_TIMER_EVENT_PAUSE);
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if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
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return snd_timer_stop_slave(timeri, false);
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else
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return snd_timer_stop1(timeri, false);
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}
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/*
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