[PATCH 3/3] ASoC: hdac_hda: fix deadlock after PCM open error

[Kai Vehmanen]

Commit 5bd70440cb0a ("ASoC: soc-dai: revert all changes to DAI
startup/shutdown sequence"), introduced a slight change of semantics
to DAI startup/shutdown. If startup() returns an error, shutdown()
is now called for the DAI.

This causes a deadlock in hdac_hda which issues a call to
snd_hda_codec_pcm_put() in case open fails. Upon error, soc_pcm_open()
will call shutdown(), and pcm_put() ends up getting called twice. Result
is a deadlock on pcm->open_mutex, as snd_device_free() gets called from
within snd_pcm_open(). Typical task backtrace looks like this:

[  334.244627]  snd_pcm_dev_disconnect+0x49/0x340 [snd_pcm]
[  334.244634]  __snd_device_disconnect.part.0+0x2c/0x50 [snd]
[  334.244640]  __snd_device_free+0x7f/0xc0 [snd]
[  334.244650]  snd_hda_codec_pcm_put+0x87/0x120 [snd_hda_codec]
[  334.244660]  soc_pcm_open+0x6a0/0xbe0 [snd_soc_core]
[  334.244676]  ? dpcm_add_paths.isra.0+0x491/0x590 [snd_soc_core]
[  334.244679]  ? kfree+0x9a/0x230
[  334.244686]  dpcm_be_dai_startup+0x255/0x300 [snd_soc_core]
[  334.244695]  dpcm_fe_dai_open+0x20e/0xf30 [snd_soc_core]
[  334.244701]  ? snd_pcm_hw_rule_muldivk+0x110/0x110 [snd_pcm]
[  334.244709]  ? dpcm_be_dai_startup+0x300/0x300 [snd_soc_core]
[  334.244714]  ? snd_pcm_attach_substream+0x3c4/0x540 [snd_pcm]
[  334.244719]  snd_pcm_open_substream+0x69a/0xb60 [snd_pcm]
[  334.244729]  ? snd_pcm_release_substream+0x30/0x30 [snd_pcm]
[  334.244732]  ? __mutex_lock_slowpath+0x10/0x10
[  334.244736]  snd_pcm_open+0x1b3/0x3c0 [snd_pcm]

Fixes: 5bd70440cb0a ("ASoC: soc-dai: revert all changes to DAI startup/shutdown sequence")
BugLink: https://github.com/thesofproject/linux/issues/2159
Signed-off-by: Kai Vehmanen <kai.vehmanen at linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
Reviewed-by: Rander Wang <rander.wang at linux.intel.com>
---
 sound/soc/codecs/hdac_hda.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/sound/soc/codecs/hdac_hda.c b/sound/soc/codecs/hdac_hda.c
index 74574b9180a5..49e6f23fc766 100644
--- a/sound/soc/codecs/hdac_hda.c
+++ b/sound/soc/codecs/hdac_hda.c
@@ -289,7 +289,6 @@ static int hdac_hda_dai_open(struct snd_pcm_substream *substream,
 	struct hdac_hda_priv *hda_pvt;
 	struct hda_pcm_stream *hda_stream;
 	struct hda_pcm *pcm;
-	int ret;
 
 	hda_pvt = snd_soc_component_get_drvdata(component);
 	pcm = snd_soc_find_pcm_from_dai(hda_pvt, dai);
@@ -300,11 +299,7 @@ static int hdac_hda_dai_open(struct snd_pcm_substream *substream,
 
 	hda_stream = &pcm->stream[substream->stream];
 
-	ret = hda_stream->ops.open(hda_stream, &hda_pvt->codec, substream);
-	if (ret < 0)
-		snd_hda_codec_pcm_put(pcm);
-
-	return ret;
+	return hda_stream->ops.open(hda_stream, &hda_pvt->codec, substream);
 }
 
 static void hdac_hda_dai_close(struct snd_pcm_substream *substream,
-- 
2.27.0