There is a race between timer and process contexts. Process context
does not disable irqs, so when a timer ticks inside process' critical
section, the system can deadlock. Fix this by a traditional _irqsave
variant of spin_lock.
Signed-off-by: Jiri Slaby <jsl...@suse.cz>
Cc: Jaroslav Kysela <pe...@perex.cz>
Cc: Takashi Iwai <ti...@suse.de>
Cc: alsa-de...@alsa-project.org
---
sound/drivers/dummy.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
index 6d6bf4093583..18a7cfc99078 100644
--- a/sound/drivers/dummy.c
+++ b/sound/drivers/dummy.c
@@ -271,10 +271,13 @@ static void dummy_systimer_update(struct
dummy_systimer_pcm *dpcm)
static int dummy_systimer_start(struct snd_pcm_substream *substream)
{
struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
- spin_lock(&dpcm->lock);
+ unsigned long flags;
+
+ spin_lock_irqsave(&dpcm->lock, flags);
dpcm->base_time = jiffies;
dummy_systimer_rearm(dpcm);
- spin_unlock(&dpcm->lock);
+ spin_unlock_irqrestore(&dpcm->lock, flags);
+
return 0;
}
@@ -322,12 +325,14 @@ static snd_pcm_uframes_t
dummy_systimer_pointer(struct snd_pcm_substream *substream)
{
struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
+ unsigned long flags;
snd_pcm_uframes_t pos;
- spin_lock(&dpcm->lock);
+ spin_lock_irqsave(&dpcm->lock, flags);
dummy_systimer_update(dpcm);
pos = dpcm->frac_pos / HZ;
- spin_unlock(&dpcm->lock);
+ spin_unlock_irqrestore(&dpcm->lock, flags);
+
return pos;
}
--
2.2.1
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