ALSA: timer: Fix race between stop and interrupt

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

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 1a97baa..9198fe2 100644 (file)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -214,11 +214,13 @@ static void snd_timer_check_master(struct snd_timer_instance *master)
                    slave->slave_id == master->slave_id) {
                        list_move_tail(&slave->open_list, &master->slave_list_head);
                        spin_lock_irq(&slave_active_lock);
+                       spin_lock(&master->timer->lock);
                        slave->master = master;
                        slave->timer = master->timer;
                        if (slave->flags & SNDRV_TIMER_IFLG_RUNNING)
                                list_add_tail(&slave->active_list,
                                              &master->slave_active_head);
+                       spin_unlock(&master->timer->lock);
                        spin_unlock_irq(&slave_active_lock);
                }
        }
@@ -344,15 +346,18 @@ int snd_timer_close(struct snd_timer_instance *timeri)
                    timer->hw.close)
                        timer->hw.close(timer);
                /* remove slave links */
+               spin_lock_irq(&slave_active_lock);
+               spin_lock(&timer->lock);
                list_for_each_entry_safe(slave, tmp, &timeri->slave_list_head,
                                         open_list) {
-                       spin_lock_irq(&slave_active_lock);
-                       _snd_timer_stop(slave, 1, SNDRV_TIMER_EVENT_RESOLUTION);
                        list_move_tail(&slave->open_list, &snd_timer_slave_list);
                        slave->master = NULL;
                        slave->timer = NULL;
-                       spin_unlock_irq(&slave_active_lock);
+                       list_del_init(&slave->ack_list);
+                       list_del_init(&slave->active_list);
                }
+               spin_unlock(&timer->lock);
+               spin_unlock_irq(&slave_active_lock);
                mutex_unlock(&register_mutex);
        }
  out:
@@ -409,7 +414,7 @@ static void snd_timer_notify1(struct snd_timer_instance *ti, int event)
        spin_lock_irqsave(&timer->lock, flags);
        list_for_each_entry(ts, &ti->slave_active_head, active_list)
                if (ts->ccallback)
-                       ts->ccallback(ti, event + 100, &tstamp, resolution);
+                       ts->ccallback(ts, event + 100, &tstamp, resolution);
        spin_unlock_irqrestore(&timer->lock, flags);
 }
 
@@ -438,10 +443,17 @@ 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)
+       if (timeri->master && timeri->timer) {
+               spin_lock(&timeri->timer->lock);
                list_add_tail(&timeri->active_list,
                              &timeri->master->slave_active_head);
+               spin_unlock(&timeri->timer->lock);
+       }
        spin_unlock_irqrestore(&slave_active_lock, flags);
        return 1; /* delayed start */
 }
@@ -459,18 +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;
 }
 
@@ -486,7 +506,17 @@ 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;
+                       }
+                       if (timeri->timer)
+                               spin_lock(&timeri->timer->lock);
                        timeri->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
+                       list_del_init(&timeri->ack_list);
+                       list_del_init(&timeri->active_list);
+                       if (timeri->timer)
+                               spin_unlock(&timeri->timer->lock);
                        spin_unlock_irqrestore(&slave_active_lock, flags);
                }
                goto __end;
@@ -495,6 +525,11 @@ 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) &&
@@ -560,10 +595,15 @@ 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;
@@ -691,8 +731,8 @@ void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left)
                        ti->cticks = ti->ticks;
                } else {
                        ti->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
-                       if (--timer->running)
-                               list_del_init(&ti->active_list);
+                       --timer->running;
+                       list_del_init(&ti->active_list);
                }
                if ((timer->hw.flags & SNDRV_TIMER_HW_TASKLET) ||
                    (ti->flags & SNDRV_TIMER_IFLG_FAST))