ASoC: dpcm: improve robustness

Avoid oopsing if there is no backend stream associated with a front end
stream.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Mark Brown <broonie@linaro.org>

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index d81b7925176006977f96df74cd61134c41294e41..591f0f3074c58b75eeb5b99a939bc9bf46ffae52 100644 (file)
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1038,6 +1038,12 @@ static int dpcm_be_dai_startup(struct snd_soc_pcm_runtime *fe, int stream)
                struct snd_pcm_substream *be_substream =
                        snd_soc_dpcm_get_substream(be, stream);
 
+               if (!be_substream) {
+                       dev_err(be->dev, "ASoC: no backend %s stream\n",
+                               stream ? "capture" : "playback");
+                       continue;
+               }
+
                /* is this op for this BE ? */
                if (!snd_soc_dpcm_be_can_update(fe, be, stream))
                        continue;
@@ -1055,7 +1061,8 @@ static int dpcm_be_dai_startup(struct snd_soc_pcm_runtime *fe, int stream)
                    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_CLOSE))
                        continue;
 
-               dev_dbg(be->dev, "ASoC: open BE %s\n", be->dai_link->name);
+               dev_dbg(be->dev, "ASoC: open %s BE %s\n",
+                       stream ? "capture" : "playback", be->dai_link->name);
 
                be_substream->runtime = be->dpcm[stream].runtime;
                err = soc_pcm_open(be_substream);