| From 95926035b187cc9fee6fb61385b7da9c28123f74 Mon Sep 17 00:00:00 2001 |
| From: Takashi Iwai <tiwai@suse.de> |
| Date: Mon, 13 Oct 2014 23:18:02 +0200 |
| Subject: ALSA: emu10k1: Fix deadlock in synth voice lookup |
| |
| From: Takashi Iwai <tiwai@suse.de> |
| |
| 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> |
| |
| --- |
| 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; |