ASoC: Use nested lock for snd_soc_dapm_mutex_lock
authorCharles Keepax <ckeepax@opensource.wolfsonmicro.com>
Tue, 29 Dec 2015 16:25:13 +0000 (16:25 +0000)
committerMark Brown <broonie@kernel.org>
Wed, 30 Dec 2015 16:48:13 +0000 (16:48 +0000)
snd_soc_dapm_mutex_lock currently uses the un-nested call which can
cause lockdep warnings when called from control handlers (a relatively
common usage) and using modules. As creating the control causes a
potential mutex inversion with the handler, creating the control will
take the controls_rwsem under the dapm_mutex and accessing the control
will take the dapm_mutex under controls_rwsem.

All the users look like they want to be using the runtime class of the
lock anyway, so this patch just changes snd_soc_dapm_mutex_lock to use
the nested call, with the SND_SOC_DAPM_CLASS_RUNTIME class.

Fixes: f6d5e586b416 ("ASoC: dapm: Add helpers to lock/unlock DAPM mutex")
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
include/sound/soc.h

index a8b4b9c8b1d2415e7220913715fc2cd4bd95212c..fb955e69a78ea29f79bd4382b492bca009cd6fe7 100644 (file)
@@ -1655,7 +1655,7 @@ extern const struct dev_pm_ops snd_soc_pm_ops;
 /* Helper functions */
 static inline void snd_soc_dapm_mutex_lock(struct snd_soc_dapm_context *dapm)
 {
-       mutex_lock(&dapm->card->dapm_mutex);
+       mutex_lock_nested(&dapm->card->dapm_mutex, SND_SOC_DAPM_CLASS_RUNTIME);
 }
 
 static inline void snd_soc_dapm_mutex_unlock(struct snd_soc_dapm_context *dapm)