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authorTakashi Iwai <tiwai@suse.de>2015-04-27 14:50:39 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-05-13 05:14:24 -0700
commit7327ee488670217fdf31787fe03ebbafd96b796e (patch)
treecb2ae8e030e05f147d030a6f5e425a9a48d65579 /sound
parentcf30fb9b72fbf301f397d6cbdc28ac69686e4798 (diff)
downloadlinux-linaro-stable-7327ee488670217fdf31787fe03ebbafd96b796e.tar.gz
ALSA: emux: Fix mutex deadlock at unloading
commit 07b0e5d49d227e3950cb13a3e8caf248ef2a310e upstream. The emux-synth driver has a possible AB/BA mutex deadlock at unloading the emu10k1 driver: snd_emux_free() -> snd_emux_detach_seq(): mutex_lock(&emu->register_mutex) -> snd_seq_delete_kernel_client() -> snd_seq_free_client(): mutex_lock(&register_mutex) snd_seq_release() -> snd_seq_free_client(): mutex_lock(&register_mutex) -> snd_seq_delete_all_ports() -> snd_emux_unuse(): mutex_lock(&emu->register_mutex) Basically snd_emux_detach_seq() doesn't need a protection of emu->register_mutex as it's already being unregistered. So, we can get rid of this for avoiding the deadlock. Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound')
-rw-r--r--sound/synth/emux/emux_seq.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/sound/synth/emux/emux_seq.c b/sound/synth/emux/emux_seq.c
index 7778b8e19782..188fda0effb0 100644
--- a/sound/synth/emux/emux_seq.c
+++ b/sound/synth/emux/emux_seq.c
@@ -124,12 +124,10 @@ snd_emux_detach_seq(struct snd_emux *emu)
if (emu->voices)
snd_emux_terminate_all(emu);
- mutex_lock(&emu->register_mutex);
if (emu->client >= 0) {
snd_seq_delete_kernel_client(emu->client);
emu->client = -1;
}
- mutex_unlock(&emu->register_mutex);
}