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authorTakashi Iwai <tiwai@suse.de>2014-10-13 23:18:02 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-10-30 09:35:13 -0700
commit8205fae0f07db86ca05108a478d5f8b7e5fe2737 (patch)
tree8f7268408cad3a6641eaa3ca023ebacb929ab66c /sound/pci/emu10k1
parentaff3c48530a9bd58edf42d94684234244c957a6b (diff)
downloadlinux-linaro-stable-8205fae0f07db86ca05108a478d5f8b7e5fe2737.tar.gz
ALSA: emu10k1: Fix deadlock in synth voice lookup
commit 95926035b187cc9fee6fb61385b7da9c28123f74 upstream. The emu10k1 voice allocator takes voice_lock spinlock. When there is no empty stream available, it tries to release a voice used by synth, and calls get_synth_voice. The callback function, snd_emu10k1_synth_get_voice(), however, also takes the voice_lock, thus it deadlocks. The fix is simply removing the voice_lock holds in snd_emu10k1_synth_get_voice(), as this is always called in the spinlock context. Reported-and-tested-by: Arthur Marsh <arthur.marsh@internode.on.net> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound/pci/emu10k1')
-rw-r--r--sound/pci/emu10k1/emu10k1_callback.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/sound/pci/emu10k1/emu10k1_callback.c b/sound/pci/emu10k1/emu10k1_callback.c
index cae36597aa71..0a34b5f1c475 100644
--- a/sound/pci/emu10k1/emu10k1_callback.c
+++ b/sound/pci/emu10k1/emu10k1_callback.c
@@ -85,6 +85,8 @@ snd_emu10k1_ops_setup(struct snd_emux *emux)
* get more voice for pcm
*
* terminate most inactive voice and give it as a pcm voice.
+ *
+ * voice_lock is already held.
*/
int
snd_emu10k1_synth_get_voice(struct snd_emu10k1 *hw)
@@ -92,12 +94,10 @@ snd_emu10k1_synth_get_voice(struct snd_emu10k1 *hw)
struct snd_emux *emu;
struct snd_emux_voice *vp;
struct best_voice best[V_END];
- unsigned long flags;
int i;
emu = hw->synth;
- spin_lock_irqsave(&emu->voice_lock, flags);
lookup_voices(emu, hw, best, 1); /* no OFF voices */
for (i = 0; i < V_END; i++) {
if (best[i].voice >= 0) {
@@ -113,11 +113,9 @@ snd_emu10k1_synth_get_voice(struct snd_emu10k1 *hw)
vp->emu->num_voices--;
vp->ch = -1;
vp->state = SNDRV_EMUX_ST_OFF;
- spin_unlock_irqrestore(&emu->voice_lock, flags);
return ch;
}
}
- spin_unlock_irqrestore(&emu->voice_lock, flags);
/* not found */
return -ENOMEM;