ALSA: timer: Fix link corruption due to double start or stop

[pandora-kernel.git] / sound / core / timer.c

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 76bdfac..39bf01d 100644 (file)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -443,6 +443,10 @@ static int snd_timer_start_slave(struct snd_timer_instance *timeri)
        unsigned long flags;
 
        spin_lock_irqsave(&slave_active_lock, flags);
+       if (timeri->flags & SNDRV_TIMER_IFLG_RUNNING) {
+               spin_unlock_irqrestore(&slave_active_lock, flags);
+               return -EBUSY;
+       }
        timeri->flags |= SNDRV_TIMER_IFLG_RUNNING;
        if (timeri->master && timeri->timer) {
                spin_lock(&timeri->timer->lock);
@@ -467,18 +471,26 @@ int snd_timer_start(struct snd_timer_instance *timeri, unsigned int ticks)
                return -EINVAL;
        if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE) {
                result = snd_timer_start_slave(timeri);
-               snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_START);
+               if (result >= 0)
+                       snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_START);
                return result;
        }
        timer = timeri->timer;
        if (timer == NULL)
                return -EINVAL;
        spin_lock_irqsave(&timer->lock, flags);
+       if (timeri->flags & (SNDRV_TIMER_IFLG_RUNNING |
+                            SNDRV_TIMER_IFLG_START)) {
+               result = -EBUSY;
+               goto unlock;
+       }
        timeri->ticks = timeri->cticks = ticks;
        timeri->pticks = 0;
        result = snd_timer_start1(timer, timeri, ticks);
+ unlock:
        spin_unlock_irqrestore(&timer->lock, flags);
-       snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_START);
+       if (result >= 0)
+               snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_START);
        return result;
 }
 
@@ -494,6 +506,10 @@ static int _snd_timer_stop(struct snd_timer_instance * timeri,
        if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE) {
                if (!keep_flag) {
                        spin_lock_irqsave(&slave_active_lock, flags);
+                       if (!(timeri->flags & SNDRV_TIMER_IFLG_RUNNING)) {
+                               spin_unlock_irqrestore(&slave_active_lock, flags);
+                               return -EBUSY;
+                       }
                        timeri->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
                        list_del_init(&timeri->ack_list);
                        list_del_init(&timeri->active_list);
@@ -505,6 +521,11 @@ static int _snd_timer_stop(struct snd_timer_instance * timeri,
        if (!timer)
                return -EINVAL;
        spin_lock_irqsave(&timer->lock, flags);
+       if (!(timeri->flags & (SNDRV_TIMER_IFLG_RUNNING |
+                              SNDRV_TIMER_IFLG_START))) {
+               spin_unlock_irqrestore(&timer->lock, flags);
+               return -EBUSY;
+       }
        list_del_init(&timeri->ack_list);
        list_del_init(&timeri->active_list);
        if ((timeri->flags & SNDRV_TIMER_IFLG_RUNNING) &&
@@ -570,10 +591,15 @@ int snd_timer_continue(struct snd_timer_instance *timeri)
        if (! timer)
                return -EINVAL;
        spin_lock_irqsave(&timer->lock, flags);
+       if (timeri->flags & SNDRV_TIMER_IFLG_RUNNING) {
+               result = -EBUSY;
+               goto unlock;
+       }
        if (!timeri->cticks)
                timeri->cticks = 1;
        timeri->pticks = 0;
        result = snd_timer_start1(timer, timeri, timer->sticks);
+ unlock:
        spin_unlock_irqrestore(&timer->lock, flags);
        snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_CONTINUE);
        return result;