From: <gregkh@linuxfoundation.org>
To: tiwai@suse.de, gregkh@linuxfoundation.org
Cc: <stable@vger.kernel.org>, <stable-commits@vger.kernel.org>
Subject: Patch "ALSA: emux: Fix mutex deadlock at unloading" has been added to the 3.14-stable tree
Date: Sat, 09 May 2015 19:24:24 +0200 [thread overview]
Message-ID: <1431192264247141@kroah.com> (raw)
This is a note to let you know that I've just added the patch titled
ALSA: emux: Fix mutex deadlock at unloading
to the 3.14-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-emux-fix-mutex-deadlock-at-unloading.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From 07b0e5d49d227e3950cb13a3e8caf248ef2a310e Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 27 Apr 2015 14:50:39 +0200
Subject: ALSA: emux: Fix mutex deadlock at unloading
From: Takashi Iwai <tiwai@suse.de>
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/synth/emux/emux_seq.c | 2 --
1 file changed, 2 deletions(-)
--- 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);
}
Patches currently in stable-queue which might be from tiwai@suse.de are
queue-3.14/alsa-emux-fix-mutex-deadlock-at-unloading.patch
queue-3.14/alsa-hda-add-mute-led-mode-control-to-thinkpad.patch
queue-3.14/alsa-emu10k1-emu10k2-32-bit-dma-mode.patch
queue-3.14/alsa-emux-fix-mutex-deadlock-in-oss-emulation.patch
queue-3.14/alsa-hda-fix-mute-led-fixed-mode.patch
queue-3.14/alsa-emu10k1-fix-card-shortname-string-buffer-overflow.patch
reply other threads:[~2015-05-09 17:24 UTC|newest]
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