FAILED: patch "[PATCH] ALSA: mixer: fix deadlock in snd_mixer_oss_set_volume" failed to apply to 4.9-stable tree

FAILED: patch "[PATCH] ALSA: mixer: fix deadlock in snd_mixer_oss_set_volume" failed to apply to 4.9-stable tree

[gregkh]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3ab7992018455ac63c33e9b3eaa7264e293e40f4 Mon Sep 17 00:00:00 2001
From: Pavel Skripkin <paskripkin@gmail.com>
Date: Sun, 24 Oct 2021 17:03:15 +0300
Subject: [PATCH] ALSA: mixer: fix deadlock in snd_mixer_oss_set_volume

In commit 411cef6adfb3 ("ALSA: mixer: oss: Fix racy access to slots")
added mutex protection in snd_mixer_oss_set_volume(). Second
mutex_lock() in same function looks like typo, fix it.

Reported-by: syzbot+ace149a75a9a0a399ac7@syzkaller.appspotmail.com
Fixes: 411cef6adfb3 ("ALSA: mixer: oss: Fix racy access to slots")
Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Link: https://lore.kernel.org/r/20211024140315.16704-1-paskripkin@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c
index d5ddc154a735..9620115cfdc0 100644
--- a/sound/core/oss/mixer_oss.c
+++ b/sound/core/oss/mixer_oss.c
@@ -313,7 +313,7 @@ static int snd_mixer_oss_set_volume(struct snd_mixer_oss_file *fmixer,
 	pslot->volume[1] = right;
 	result = (left & 0xff) | ((right & 0xff) << 8);
  unlock:
-	mutex_lock(&mixer->reg_mutex);
+	mutex_unlock(&mixer->reg_mutex);
 	return result;
 }