Commit 07b0e5d4 authored by Takashi Iwai's avatar Takashi Iwai

ALSA: emux: Fix mutex deadlock at unloading

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.

Cc: <>
Signed-off-by: default avatarTakashi Iwai <>
parent d0226082
......@@ -124,12 +124,10 @@ snd_emux_detach_seq(struct snd_emux *emu)
if (emu->voices)
if (emu->client >= 0) {
emu->client = -1;
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment