ALSA: hda - Fix concurrent hash accesses

The amp and caps hashes aren't protected properly for concurrent
accesses.  Protect them via a new mutex now.

But it can't be so simple as originally thought: since the update of a
hash table entry itself might trigger the power-up sequence which
again accesses the hash table, we can't cover the whole function
simply via mutex.  Thus the update part has to be split from the mutex
and revalidated.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/sound/pci/hda/hda_codec.h b/sound/pci/hda/hda_codec.h
index fce30b42bc4..29a311b05f2 100644
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -827,6 +827,7 @@ struct hda_codec {
 
 	struct mutex spdif_mutex;
 	struct mutex control_mutex;
+	struct mutex hash_mutex;
 	struct snd_array spdif_out;
 	unsigned int spdif_in_enable;	/* SPDIF input enable? */
 	const hda_nid_t *slave_dig_outs; /* optional digital out slave widgets */