[PATCH] ALSA: hda/realtek: Fix deadlock by COEF mutex

[Takashi Iwai <tiwai@xxxxxxx>]

The recently introduced coef_mutex for Realtek codec seems causing a
deadlock when the relevant code is invoked from the power-off state;
then the HD-audio core tries to power-up internally, and this kicks
off the codec runtime PM code that tries to take the same coef_mutex.

In order to avoid the deadlock, do the temporary power up/down around
the coef_mutex acquisition and release.  This assures that the
power-up sequence runs before the mutex, hence no re-entrance will
happen.

Fixes: b837a9f5ab3b ("ALSA: hda: realtek: Fix race at concurrent COEF updates")
Reported-and-tested-by: Julian Wollrath <jwollrath@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220214132838.4db10fca@schienar
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
 sound/pci/hda/patch_realtek.c | 39 +++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 15 deletions(-)

diff --git a/sound/pci/hda/patch_realtek.c b/sound/pci/hda/patch_realtek.c
index 9473fb76ff19..3a42457984e9 100644
--- a/sound/pci/hda/patch_realtek.c
+++ b/sound/pci/hda/patch_realtek.c
@@ -138,6 +138,22 @@ struct alc_spec {
  * COEF access helper functions
  */
 
+static void coef_mutex_lock(struct hda_codec *codec)
+{
+	struct alc_spec *spec = codec->spec;
+
+	snd_hda_power_up_pm(codec);
+	mutex_lock(&spec->coef_mutex);
+}
+
+static void coef_mutex_unlock(struct hda_codec *codec)
+{
+	struct alc_spec *spec = codec->spec;
+
+	mutex_unlock(&spec->coef_mutex);
+	snd_hda_power_down_pm(codec);
+}
+
 static int __alc_read_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
 				 unsigned int coef_idx)
 {
@@ -151,12 +167,11 @@ static int __alc_read_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
 static int alc_read_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
 			       unsigned int coef_idx)
 {
-	struct alc_spec *spec = codec->spec;
 	unsigned int val;
 
-	mutex_lock(&spec->coef_mutex);
+	coef_mutex_lock(codec);
 	val = __alc_read_coefex_idx(codec, nid, coef_idx);
-	mutex_unlock(&spec->coef_mutex);
+	coef_mutex_unlock(codec);
 	return val;
 }
 
@@ -173,11 +188,9 @@ static void __alc_write_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
 static void alc_write_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
 				 unsigned int coef_idx, unsigned int coef_val)
 {
-	struct alc_spec *spec = codec->spec;
-
-	mutex_lock(&spec->coef_mutex);
+	coef_mutex_lock(codec);
 	__alc_write_coefex_idx(codec, nid, coef_idx, coef_val);
-	mutex_unlock(&spec->coef_mutex);
+	coef_mutex_unlock(codec);
 }
 
 #define alc_write_coef_idx(codec, coef_idx, coef_val) \
@@ -198,11 +211,9 @@ static void alc_update_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
 				  unsigned int coef_idx, unsigned int mask,
 				  unsigned int bits_set)
 {
-	struct alc_spec *spec = codec->spec;
-
-	mutex_lock(&spec->coef_mutex);
+	coef_mutex_lock(codec);
 	__alc_update_coefex_idx(codec, nid, coef_idx, mask, bits_set);
-	mutex_unlock(&spec->coef_mutex);
+	coef_mutex_unlock(codec);
 }
 
 #define alc_update_coef_idx(codec, coef_idx, mask, bits_set)	\
@@ -235,9 +246,7 @@ struct coef_fw {
 static void alc_process_coef_fw(struct hda_codec *codec,
 				const struct coef_fw *fw)
 {
-	struct alc_spec *spec = codec->spec;
-
-	mutex_lock(&spec->coef_mutex);
+	coef_mutex_lock(codec);
 	for (; fw->nid; fw++) {
 		if (fw->mask == (unsigned short)-1)
 			__alc_write_coefex_idx(codec, fw->nid, fw->idx, fw->val);
@@ -245,7 +254,7 @@ static void alc_process_coef_fw(struct hda_codec *codec,
 			__alc_update_coefex_idx(codec, fw->nid, fw->idx,
 						fw->mask, fw->val);
 	}
-	mutex_unlock(&spec->coef_mutex);
+	coef_mutex_unlock(codec);
 }
 
 /*
-- 
2.31.1