diff options
| author | Takashi Iwai <tiwai@suse.de> | 2015-07-17 15:22:33 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-08-10 12:21:53 -0700 |
| commit | 898dbc106e50ab6de4106e2415d0f40e260903c4 (patch) | |
| tree | 3f4bed88b289a7b205822e0dd797a96348740b91 | |
| parent | 2b16e01ae6b5c0c5e1f382fcad51a3053270374a (diff) | |
ALSA: pcm: Fix lockdep warning with nonatomic PCM ops
commit 67756e3191c90e7c0b94b8b2fb63de255b6cd337 upstream.
With the nonatomic PCM ops, the system may spew lockdep warnings like:
=============================================
[ INFO: possible recursive locking detected ]
4.2.0-rc1-jeejaval3 #12 Not tainted
---------------------------------------------
aplay/4029 is trying to acquire lock:
(snd_pcm_link_rwsem){.+.+.+}, at: [<ffffffff816fd473>] snd_pcm_stream_lock+0x43/0x60
but task is already holding lock:
(snd_pcm_link_rwsem){.+.+.+}, at: [<ffffffff816fcf29>] snd_pcm_action_nonatomic+0x29/0x80
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(snd_pcm_link_rwsem);
lock(snd_pcm_link_rwsem);
Although this is false-positive as the rwsem is taken always as
read-only for these code paths, it's certainly annoying to see this at
any occasion. A simple fix is to use down_read_nested() in
snd_pcm_stream_lock() that can be called inside another lock.
Reported-by: Vinod Koul <vinod.koul@intel.com>
Reported-by: Jeeja Kp <jeeja.kp@intel.com>
Tested-by: Jeeja Kp <jeeja.kp@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | sound/core/pcm_native.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index d126c03361ae..75888dd38a7f 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -85,7 +85,7 @@ static DECLARE_RWSEM(snd_pcm_link_rwsem); void snd_pcm_stream_lock(struct snd_pcm_substream *substream) { if (substream->pcm->nonatomic) { - down_read(&snd_pcm_link_rwsem); + down_read_nested(&snd_pcm_link_rwsem, SINGLE_DEPTH_NESTING); mutex_lock(&substream->self_group.mutex); } else { read_lock(&snd_pcm_link_rwlock); |