From: Takashi Iwai Date: Fri, 17 Jul 2015 13:22:33 +0000 (+0200) Subject: ALSA: pcm: Fix lockdep warning with nonatomic PCM ops X-Git-Tag: omap-for-v4.3/fixes-merge-window~198^2~7 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=67756e3191c90e7c0b94b8b2fb63de255b6cd337;p=pandora-kernel.git 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: [] snd_pcm_stream_lock+0x43/0x60 but task is already holding lock: (snd_pcm_link_rwsem){.+.+.+}, at: [] 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 Reported-by: Jeeja Kp Tested-by: Jeeja Kp Cc: Signed-off-by: Takashi Iwai --- Reading git-diff-tree failed