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 Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/core/pcm_native.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

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);