ALSA: hda: Manage concurrent reg access more properly

In the commit 8e85def5723e ("ALSA: hda: enable regmap internal
locking"), we re-enabled the regmap lock due to the reported
regression that showed the possible concurrent accesses.  It was a
temporary workaround, and there are still a few opened races even
after the revert.  In this patch, we cover those still opened windows
with a proper mutex lock and disable the regmap internal lock again.

First off, the patch introduces a new snd_hdac_device.regmap_lock
mutex that is applied for each snd_hdac_regmap_*() call, including
read, write and update helpers.  The mutex is applied carefully so
that it won't block the self-power-up procedure in the helper
function.  Also, this assures the protection for the accesses without
regmap, too.

The snd_hdac_regmap_update_raw() is refactored to use the standard
regmap_update_bits_check() function instead of the open-code.  The
non-regmap case is still open-coded but it's an easy part.  The all
read and write operations are in the single mutex protection, so it's
now race-free.

In addition, a couple of new helper functions are added:
snd_hdac_regmap_update_raw_once() and snd_hdac_regmap_sync().  Both
are called from HD-audio legacy driver.  The former is to initialize
the given verb bits but only once when it's not initialized yet.  Due
to this condition, the function invokes regcache_cache_only(), and
it's now performed inside the regmap_lock (formerly it was racy) too.
The latter function is for simply invoking regcache_sync() inside the
regmap_lock, which is called from the codec resume call path.
Along with that, the HD-audio codec driver code is slightly modified /
simplified to adapt those new functions.

And finally, snd_hdac_regmap_read_raw(), *_write_raw(), etc are
rewritten with the helper macro.  It's just for simplification because
the code logic is identical among all those functions.

Tested-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20200109090104.26073-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 16 insertions, 14 deletions

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index 4377b2aba835..83aa4c1015d2 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -1267,6 +1267,18 @@ int snd_hda_override_amp_caps(struct hda_codec *codec, hda_nid_t nid, int dir,
 }
 EXPORT_SYMBOL_GPL(snd_hda_override_amp_caps);
 
+static unsigned int encode_amp(struct hda_codec *codec, hda_nid_t nid,
+			       int ch, int dir, int idx)
+{
+	unsigned int cmd = snd_hdac_regmap_encode_amp(nid, ch, dir, idx);
+
+	/* enable fake mute if no h/w mute but min=mute */
+	if ((query_amp_caps(codec, nid, dir) &
+	     (AC_AMPCAP_MUTE | AC_AMPCAP_MIN_MUTE)) == AC_AMPCAP_MIN_MUTE)
+		cmd |= AC_AMP_FAKE_MUTE;
+	return cmd;
+}
+
 /**
  * snd_hda_codec_amp_update - update the AMP mono value
  * @codec: HD-audio codec
@@ -1282,12 +1294,8 @@ EXPORT_SYMBOL_GPL(snd_hda_override_amp_caps);
 int snd_hda_codec_amp_update(struct hda_codec *codec, hda_nid_t nid,
 			     int ch, int dir, int idx, int mask, int val)
 {
-	unsigned int cmd = snd_hdac_regmap_encode_amp(nid, ch, dir, idx);
+	unsigned int cmd = encode_amp(codec, nid, ch, dir, idx);
 
-	/* enable fake mute if no h/w mute but min=mute */
-	if ((query_amp_caps(codec, nid, dir) &
-	     (AC_AMPCAP_MUTE | AC_AMPCAP_MIN_MUTE)) == AC_AMPCAP_MIN_MUTE)
-		cmd |= AC_AMP_FAKE_MUTE;
 	return snd_hdac_regmap_update_raw(&codec->core, cmd, mask, val);
 }
 EXPORT_SYMBOL_GPL(snd_hda_codec_amp_update);
@@ -1335,16 +1343,11 @@ EXPORT_SYMBOL_GPL(snd_hda_codec_amp_stereo);
 int snd_hda_codec_amp_init(struct hda_codec *codec, hda_nid_t nid, int ch,
 			   int dir, int idx, int mask, int val)
 {
-	int orig;
+	unsigned int cmd = encode_amp(codec, nid, ch, dir, idx);
 
 	if (!codec->core.regmap)
 		return -EINVAL;
-	regcache_cache_only(codec->core.regmap, true);
-	orig = snd_hda_codec_amp_read(codec, nid, ch, dir, idx);
-	regcache_cache_only(codec->core.regmap, false);
-	if (orig >= 0)
-		return 0;
-	return snd_hda_codec_amp_update(codec, nid, ch, dir, idx, mask, val);
+	return snd_hdac_regmap_update_raw_once(&codec->core, cmd, mask, val);
 }
 EXPORT_SYMBOL_GPL(snd_hda_codec_amp_init);
 
@@ -2905,8 +2908,7 @@ static void hda_call_codec_resume(struct hda_codec *codec)
 	else {
 		if (codec->patch_ops.init)
 			codec->patch_ops.init(codec);
-		if (codec->core.regmap)
-			regcache_sync(codec->core.regmap);
+		snd_hda_regmap_sync(codec);
 	}
 
 	if (codec->jackpoll_interval)