This is a note to let you know that I've just added the patch titled
ALSA: emu10k1: Fix deadlock in synth voice lookup
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
alsa-emu10k1-fix-deadlock-in-synth-voice-lookup.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 95926035b187cc9fee6fb61385b7da9c28123f74 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@xxxxxxx>
Date: Mon, 13 Oct 2014 23:18:02 +0200
Subject: ALSA: emu10k1: Fix deadlock in synth voice lookup
From: Takashi Iwai <tiwai@xxxxxxx>
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@xxxxxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/pci/emu10k1/emu10k1_callback.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- 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 *e
* 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_e
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_e
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;
Patches currently in stable-queue which might be from tiwai@xxxxxxx are
queue-3.10/alsa-pcm-use-the-same-dma-mmap-codepath-both-for-arm-and-arm64.patch
queue-3.10/alsa-usb-audio-add-support-for-steinberg-ur22-usb-interface.patch
queue-3.10/alsa-emu10k1-fix-deadlock-in-synth-voice-lookup.patch
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