[alsa-devel] [PATCH 2/3] ASoC: SOF: Intel: hda: hda-dai: fix oops on hda_link .hw_free

[Pierre-Louis Bossart]

When the PCM_PARAM IPC fails while configuring the FE, the kernel
oopses in the HDaudio link DMA .hw_free operation. The root cause is a
NULL dma_data since the BE .hw_params was never called by the SOC
core.

This error can also happen if the HDaudio link DMA configuration IPC
fails in the BE .hw_params.

This patches makes sure the dma_data is properly saved in .hw_params,
and tested before being use in hw_free.

GitHub issue: https://github.com/thesofproject/linux/issues/1417

Reviewed-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen at linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 sound/soc/sof/intel/hda-dai.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/sound/soc/sof/intel/hda-dai.c b/sound/soc/sof/intel/hda-dai.c
index 8796f385be76..896d21984b73 100644
--- a/sound/soc/sof/intel/hda-dai.c
+++ b/sound/soc/sof/intel/hda-dai.c
@@ -216,6 +216,8 @@ static int hda_link_hw_params(struct snd_pcm_substream *substream,
 		link_dev = hda_link_stream_assign(bus, substream);
 		if (!link_dev)
 			return -EBUSY;
+
+		snd_soc_dai_set_dma_data(dai, substream, (void *)link_dev);
 	}
 
 	stream_tag = hdac_stream(link_dev)->stream_tag;
@@ -228,8 +230,6 @@ static int hda_link_hw_params(struct snd_pcm_substream *substream,
 	if (ret < 0)
 		return ret;
 
-	snd_soc_dai_set_dma_data(dai, substream, (void *)link_dev);
-
 	link = snd_hdac_ext_bus_get_link(bus, codec_dai->component->name);
 	if (!link)
 		return -EINVAL;
@@ -361,6 +361,13 @@ static int hda_link_hw_free(struct snd_pcm_substream *substream,
 	bus = hstream->bus;
 	rtd = snd_pcm_substream_chip(substream);
 	link_dev = snd_soc_dai_get_dma_data(dai, substream);
+
+	if (!link_dev) {
+		dev_dbg(dai->dev,
+			"%s: link_dev is not assigned\n", __func__);
+		return -EINVAL;
+	}
+
 	hda_stream = hstream_to_sof_hda_stream(link_dev);
 
 	/* free the link DMA channel in the FW */
-- 
2.20.1