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| author | Takashi Iwai <tiwai@suse.de> | 2015-04-27 14:50:39 +0200 |
|---|---|---|
| committer | Zefan Li <lizefan@huawei.com> | 2015-09-18 09:20:32 +0800 |
| commit | 0243c10d3341502b3653b71abfe7b4da068a2a02 (patch) | |
| tree | 5fe6ca383594c53638d78684d0cc8dd43d0b63ca | |
| parent | 96a987dfe32ffe562be8876392d0539437b0d780 (diff) | |
| download | lwn-0243c10d3341502b3653b71abfe7b4da068a2a02.tar.gz lwn-0243c10d3341502b3653b71abfe7b4da068a2a02.zip | |
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(®ister_mutex)
snd_seq_release() ->
snd_seq_free_client(): mutex_lock(®ister_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: Zefan Li <lizefan@huawei.com>
| -rw-r--r-- | sound/synth/emux/emux_seq.c | 2 |
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); } |