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| author | Takashi Iwai <tiwai@suse.de> | 2014-10-13 23:18:02 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-10-30 09:35:13 -0700 |
| commit | 8205fae0f07db86ca05108a478d5f8b7e5fe2737 (patch) | |
| tree | 8f7268408cad3a6641eaa3ca023ebacb929ab66c /sound/pci | |
| parent | aff3c48530a9bd58edf42d94684234244c957a6b (diff) | |
| download | lwn-8205fae0f07db86ca05108a478d5f8b7e5fe2737.tar.gz lwn-8205fae0f07db86ca05108a478d5f8b7e5fe2737.zip | |
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')
| -rw-r--r-- | sound/pci/emu10k1/emu10k1_callback.c | 6 |
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; |