Unverified Commit 3c75c0ea authored by Takashi Iwai's avatar Takashi Iwai Committed by Mark Brown
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ASoC: soc-pcm: Fix DPCM lockdep warning due to nested stream locks 



The recent change for DPCM locking caused spurious lockdep warnings.
Actually the warnings are false-positive, as those are triggered due
to the nested stream locks for FE and BE.  Since both locks belong to
the same lock class, lockdep sees it as if a deadlock.

For fixing this, we need to take PCM stream locks for BE with the
nested lock primitives.  Since currently snd_pcm_stream_lock*() helper
assumes only the top-level single locking, a new helper function
snd_pcm_stream_lock_irqsave_nested() is defined for a single-depth
nested lock, which is now used in the BE DAI trigger that is always
performed inside a FE stream lock.

Fixes: b2ae8066 ("ASoC: soc-pcm: serialize BE triggers")
Reported-and-tested-by: default avatarHans de Goede <hdegoede@redhat.com>
Reported-and-tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/73018f3c-9769-72ea-0325-b3f8e2381e30@redhat.com
Link: https://lore.kernel.org/alsa-devel/9a0abddd-49e9-872d-2f00-a1697340f786@samsung.com


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20220119155249.26754-2-tiwai@suse.de


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent fb25621d

include/sound/pcm.h

+15 −0
Original line number Diff line number Diff line
@@ -614,6 +614,7 @@ void snd_pcm_stream_unlock(struct snd_pcm_substream *substream); 
void snd_pcm_stream_lock_irq(struct snd_pcm_substream *substream);

void snd_pcm_stream_unlock_irq(struct snd_pcm_substream *substream);

unsigned long _snd_pcm_stream_lock_irqsave(struct snd_pcm_substream *substream);

unsigned long _snd_pcm_stream_lock_irqsave_nested(struct snd_pcm_substream *substream);



/**

 * snd_pcm_stream_lock_irqsave - Lock the PCM stream
@@ -632,6 +633,20 @@ unsigned long _snd_pcm_stream_lock_irqsave(struct snd_pcm_substream *substream); 
void snd_pcm_stream_unlock_irqrestore(struct snd_pcm_substream *substream,

				      unsigned long flags);



/**

 * snd_pcm_stream_lock_irqsave_nested - Single-nested PCM stream locking

 * @substream: PCM substream

 * @flags: irq flags

 *

 * This locks the PCM stream like snd_pcm_stream_lock_irqsave() but with

 * the single-depth lockdep subclass.

 */

#define snd_pcm_stream_lock_irqsave_nested(substream, flags)		\

	do {								\

		typecheck(unsigned long, flags);			\

		flags = _snd_pcm_stream_lock_irqsave_nested(substream); \

	} while (0)



/**

 * snd_pcm_group_for_each_entry - iterate over the linked substreams

 * @s: the iterator

sound/core/pcm_native.c

+13 −0
Original line number Diff line number Diff line
@@ -172,6 +172,19 @@ unsigned long _snd_pcm_stream_lock_irqsave(struct snd_pcm_substream *substream) 
}

EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave);



unsigned long _snd_pcm_stream_lock_irqsave_nested(struct snd_pcm_substream *substream)

{

	unsigned long flags = 0;

	if (substream->pcm->nonatomic)

		mutex_lock_nested(&substream->self_group.mutex,

				  SINGLE_DEPTH_NESTING);

	else

		spin_lock_irqsave_nested(&substream->self_group.lock, flags,

					 SINGLE_DEPTH_NESTING);

	return flags;

}

EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave_nested);



/**

 * snd_pcm_stream_unlock_irqrestore - Unlock the PCM stream

 * @substream: PCM substream

sound/soc/soc-pcm.c

+3 −3
Original line number Diff line number Diff line
@@ -46,8 +46,8 @@ static inline void snd_soc_dpcm_stream_lock_irq(struct snd_soc_pcm_runtime *rtd, 
	snd_pcm_stream_lock_irq(snd_soc_dpcm_get_substream(rtd, stream));

}



#define snd_soc_dpcm_stream_lock_irqsave(rtd, stream, flags) \

	snd_pcm_stream_lock_irqsave(snd_soc_dpcm_get_substream(rtd, stream), flags)

#define snd_soc_dpcm_stream_lock_irqsave_nested(rtd, stream, flags) \

	snd_pcm_stream_lock_irqsave_nested(snd_soc_dpcm_get_substream(rtd, stream), flags)



static inline void snd_soc_dpcm_stream_unlock_irq(struct snd_soc_pcm_runtime *rtd,

						  int stream)
@@ -2094,7 +2094,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
		be = dpcm->be;

		be_substream = snd_soc_dpcm_get_substream(be, stream);



		snd_soc_dpcm_stream_lock_irqsave(be, stream, flags);

		snd_soc_dpcm_stream_lock_irqsave_nested(be, stream, flags);



		/* is this op for this BE ? */

		if (!snd_soc_dpcm_be_can_update(fe, be, stream))