ALSA: hda - Don't assume non-NULL PCM ops

The PCM ops might be set NULL, or cleared to NULL when the driver is
unbound.  Give a proper NULL check at each place to be more robust.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_codec.c

@@ -4525,7 +4525,11 @@ int snd_hda_codec_prepare(struct hda_codec *codec,
 {
 	int ret;
 	mutex_lock(&codec->bus->prepare_mutex);
-	ret = hinfo->ops.prepare(hinfo, codec, stream, format, substream);
+	if (hinfo->ops.prepare)
+		ret = hinfo->ops.prepare(hinfo, codec, stream, format,
+					 substream);
+	else
+		ret = -ENODEV;
 	if (ret >= 0)
 		purify_inactive_streams(codec);
 	mutex_unlock(&codec->bus->prepare_mutex);
@@ -4546,7 +4550,8 @@ void snd_hda_codec_cleanup(struct hda_codec *codec,
 			   struct snd_pcm_substream *substream)
 {
 	mutex_lock(&codec->bus->prepare_mutex);
-	hinfo->ops.cleanup(hinfo, codec, substream);
+	if (hinfo->ops.cleanup)
+		hinfo->ops.cleanup(hinfo, codec, substream);
 	mutex_unlock(&codec->bus->prepare_mutex);
 }
 EXPORT_SYMBOL_GPL(snd_hda_codec_cleanup);

sound/pci/hda/hda_controller.c

@@ -416,7 +416,8 @@ static int azx_pcm_close(struct snd_pcm_substream *substream)
 	azx_dev->running = 0;
 	spin_unlock_irqrestore(&chip->reg_lock, flags);
 	azx_release_device(azx_dev);
-	hinfo->ops.close(hinfo, apcm->codec, substream);
+	if (hinfo->ops.close)
+		hinfo->ops.close(hinfo, apcm->codec, substream);
 	snd_hda_power_down(apcm->codec);
 	mutex_unlock(&chip->open_mutex);
 	return 0;
@@ -808,8 +809,8 @@ static int azx_pcm_open(struct snd_pcm_substream *substream)
 	mutex_lock(&chip->open_mutex);
 	azx_dev = azx_assign_device(chip, substream);
 	if (azx_dev == NULL) {
-		mutex_unlock(&chip->open_mutex);
-		return -EBUSY;
+		err = -EBUSY;
+		goto unlock;
 	}
 	runtime->hw = azx_pcm_hw;
 	runtime->hw.channels_min = hinfo->channels_min;
@@ -844,12 +845,13 @@ static int azx_pcm_open(struct snd_pcm_substream *substream)
 	snd_pcm_hw_constraint_step(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
 				   buff_step);
 	snd_hda_power_up(apcm->codec);
-	err = hinfo->ops.open(hinfo, apcm->codec, substream);
+	if (hinfo->ops.open)
+		err = hinfo->ops.open(hinfo, apcm->codec, substream);
+	else
+		err = -ENODEV;
 	if (err < 0) {
 		azx_release_device(azx_dev);
-		snd_hda_power_down(apcm->codec);
-		mutex_unlock(&chip->open_mutex);
-		return err;
+		goto powerdown;
 	}
 	snd_pcm_limit_hw_rates(runtime);
 	/* sanity check */
@@ -858,10 +860,10 @@ static int azx_pcm_open(struct snd_pcm_substream *substream)
 	    snd_BUG_ON(!runtime->hw.formats) ||
 	    snd_BUG_ON(!runtime->hw.rates)) {
 		azx_release_device(azx_dev);
-		hinfo->ops.close(hinfo, apcm->codec, substream);
-		snd_hda_power_down(apcm->codec);
-		mutex_unlock(&chip->open_mutex);
-		return -EINVAL;
+		if (hinfo->ops.close)
+			hinfo->ops.close(hinfo, apcm->codec, substream);
+		err = -EINVAL;
+		goto powerdown;
 	}
 
 	/* disable LINK_ATIME timestamps for capture streams
@@ -880,6 +882,12 @@ static int azx_pcm_open(struct snd_pcm_substream *substream)
 	snd_pcm_set_sync(substream);
 	mutex_unlock(&chip->open_mutex);
 	return 0;
+
+ powerdown:
+	snd_hda_power_down(apcm->codec);
+ unlock:
+	mutex_unlock(&chip->open_mutex);
+	return err;
 }
 
 static int azx_pcm_mmap(struct snd_pcm_substream *substream,