ALSA: jack: Fix mutex call in snd_jack_report()
authorTakashi Iwai <tiwai@suse.de>
Thu, 6 Jul 2023 15:53:57 +0000 (17:53 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 19 Jul 2023 14:21:47 +0000 (16:21 +0200)
commit14eb1a2b6f9152b1303dcce663a923e8911a824a
tree56647f6e66829ee86b56233ab2c093b53bdaf8ae
parent83c6725556d4b0132de2621fa785e4fed278727e
ALSA: jack: Fix mutex call in snd_jack_report()

commit 89dbb335cb6a627a4067bc42caa09c8bc3326d40 upstream.

snd_jack_report() is supposed to be callable from an IRQ context, too,
and it's indeed used in that way from virtsnd driver.  The fix for
input_dev race in commit 1b6a6fc5280e ("ALSA: jack: Access input_dev
under mutex"), however, introduced a mutex lock in snd_jack_report(),
and this resulted in a potential sleep-in-atomic.

For addressing that problem, this patch changes the relevant code to
use the object get/put and removes the mutex usage.  That is,
snd_jack_report(), it takes input_get_device() and leaves with
input_put_device() for assuring the input_dev being assigned.

Although the whole mutex could be reduced, we keep it because it can
be still a protection for potential races between creation and
deletion.

Fixes: 1b6a6fc5280e ("ALSA: jack: Access input_dev under mutex")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/cf95f7fe-a748-4990-8378-000491b40329@moroto.mountain
Tested-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20230706155357.3470-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sound/core/jack.c