diff options
authorTakashi Iwai <tiwai@suse.de>2015-07-17 15:22:33 +0200
committerTakashi Iwai <tiwai@suse.de>2015-07-17 15:36:54 +0200
commit67756e3191c90e7c0b94b8b2fb63de255b6cd337 (patch)
parent98973f2f083a5ec580da8bbb685e6baa93613546 (diff)
ALSA: pcm: Fix lockdep warning with nonatomic PCM ops
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>
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);
} else {

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