[alsa-devel] [PATCH] ASoC: hdac_hda: fix race in device removal

[Pierre-Louis Bossart]

From: Kai Vehmanen <kai.vehmanen at linux.intel.com>

When ASoC card instance is removed containing a HDA codec,
hdac_hda_codec_remove() may run in parallel with codec resume.
This will cause problems if the HDA link is freed with
snd_hdac_ext_bus_link_put() while the codec is still in
middle of its resume process.

To fix this, change the order such that pm_runtime_disable()
is called before the link is freed. This will ensure any
pending runtime PM action is completed before proceeding
to free the link.

This issue can be easily hit with e.g. SOF driver by loading and
unloading the drivers.

Signed-off-by: Kai Vehmanen <kai.vehmanen at linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 sound/soc/codecs/hdac_hda.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/codecs/hdac_hda.c b/sound/soc/codecs/hdac_hda.c
index 298761a26180..6803d39e09a5 100644
--- a/sound/soc/codecs/hdac_hda.c
+++ b/sound/soc/codecs/hdac_hda.c
@@ -500,8 +500,8 @@ static void hdac_hda_codec_remove(struct snd_soc_component *component)
 		return;
 	}
 
-	snd_hdac_ext_bus_link_put(hdev->bus, hlink);
 	pm_runtime_disable(&hdev->dev);
+	snd_hdac_ext_bus_link_put(hdev->bus, hlink);
 }
 
 static const struct snd_soc_dapm_route hdac_hda_dapm_routes[] = {
-- 
2.20.1