[PATCH v2] ASoC: soc-pcm: don't use soc_pcm_ret() on .prepare callback

[Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>]

commit 1f5664351410 ("ASoC: lower "no backend DAIs enabled for ... Port"
log severity") ignores -EINVAL error message on common soc_pcm_ret().
It is used from many functions, ignoring -EINVAL is over-kill.

The reason why -EINVAL was ignored was it really should only be used
upon invalid parameters coming from userspace and in that case we don't
want to log an error since we do not want to give userspace a way to do
a denial-of-service attack on the syslog / diskspace.

So don't use soc_pcm_ret() on .prepare callback is better idea.

Link: https://lore.kernel.org/r/87v7vptzap.wl-kuninori.morimoto.gx@xxxxxxxxxxx
Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
---
v1 -> v2
	- Change idea not to use soc_pcm_ret() on .prepare callback

 sound/soc/soc-pcm.c | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 1150455619aa4..88b3ad5a25520 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -38,7 +38,6 @@ static inline int _soc_pcm_ret(struct snd_soc_pcm_runtime *rtd,
 	switch (ret) {
 	case -EPROBE_DEFER:
 	case -ENOTSUPP:
-	case -EINVAL:
 		break;
 	default:
 		dev_err(rtd->dev,
@@ -986,7 +985,13 @@ static int __soc_pcm_prepare(struct snd_soc_pcm_runtime *rtd,
 	}
 
 out:
-	return soc_pcm_ret(rtd, ret);
+	/*
+	 * Don't use soc_pcm_ret() on .prepare callback to lower error log severity
+	 *
+	 * We don't want to log an error since we do not want to give userspace a way to do a
+	 * denial-of-service attack on the syslog / diskspace.
+	 */
+	return ret;
 }
 
 /* PCM prepare ops for non-DPCM streams */
@@ -998,6 +1003,13 @@ static int soc_pcm_prepare(struct snd_pcm_substream *substream)
 	snd_soc_dpcm_mutex_lock(rtd);
 	ret = __soc_pcm_prepare(rtd, substream);
 	snd_soc_dpcm_mutex_unlock(rtd);
+
+	/*
+	 * Don't use soc_pcm_ret() on .prepare callback to lower error log severity
+	 *
+	 * We don't want to log an error since we do not want to give userspace a way to do a
+	 * denial-of-service attack on the syslog / diskspace.
+	 */
 	return ret;
 }
 
@@ -2539,7 +2551,13 @@ int dpcm_be_dai_prepare(struct snd_soc_pcm_runtime *fe, int stream)
 		be->dpcm[stream].state = SND_SOC_DPCM_STATE_PREPARE;
 	}
 
-	return soc_pcm_ret(fe, ret);
+	/*
+	 * Don't use soc_pcm_ret() on .prepare callback to lower error log severity
+	 *
+	 * We don't want to log an error since we do not want to give userspace a way to do a
+	 * denial-of-service attack on the syslog / diskspace.
+	 */
+	return ret;
 }
 
 static int dpcm_fe_dai_prepare(struct snd_pcm_substream *substream)
@@ -2579,7 +2597,13 @@ static int dpcm_fe_dai_prepare(struct snd_pcm_substream *substream)
 	dpcm_set_fe_update_state(fe, stream, SND_SOC_DPCM_UPDATE_NO);
 	snd_soc_dpcm_mutex_unlock(fe);
 
-	return soc_pcm_ret(fe, ret);
+	/*
+	 * Don't use soc_pcm_ret() on .prepare callback to lower error log severity
+	 *
+	 * We don't want to log an error since we do not want to give userspace a way to do a
+	 * denial-of-service attack on the syslog / diskspace.
+	 */
+	return ret;
 }
 
 static int dpcm_run_update_shutdown(struct snd_soc_pcm_runtime *fe, int stream)
-- 
2.43.0