ALSA: compress_offload: Use automatic cleanup of kfree()

There are common patterns where a temporary buffer is allocated and
freed at the exit, and those can be simplified with the recent cleanup
mechanism via __free(kfree).

A caveat is that some allocations are memdup_user() and they return an
error pointer instead of NULL.  Those need special cares and the value
has to be cleared with no_free_ptr() at the allocation error path.

Other than that, the conversions are straightforward.

No functional changes, only code refactoring.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20240222111509.28390-4-tiwai@suse.de

sound/core/compress_offload.c

@@ -465,7 +465,7 @@ static int
 snd_compr_get_codec_caps(struct snd_compr_stream *stream, unsigned long arg)
 {
 	int retval;
-	struct snd_compr_codec_caps *caps;
+	struct snd_compr_codec_caps *caps __free(kfree) = NULL;
 
 	if (!stream->ops->get_codec_caps)
 		return -ENXIO;
@@ -476,12 +476,9 @@ snd_compr_get_codec_caps(struct snd_compr_stream *stream, unsigned long arg)
 
 	retval = stream->ops->get_codec_caps(stream, caps);
 	if (retval)
-		goto out;
+		return retval;
 	if (copy_to_user((void __user *)arg, caps, sizeof(*caps)))
-		retval = -EFAULT;
-
-out:
-	kfree(caps);
+		return -EFAULT;
 	return retval;
 }
 #endif /* !COMPR_CODEC_CAPS_OVERFLOW */
@@ -586,7 +583,7 @@ static int snd_compress_check_input(struct snd_compr_params *params)
 static int
 snd_compr_set_params(struct snd_compr_stream *stream, unsigned long arg)
 {
-	struct snd_compr_params *params;
+	struct snd_compr_params *params __free(kfree) = NULL;
 	int retval;
 
 	if (stream->runtime->state == SNDRV_PCM_STATE_OPEN || stream->next_track) {
@@ -596,24 +593,22 @@ snd_compr_set_params(struct snd_compr_stream *stream, unsigned long arg)
 		 */
 		params = memdup_user((void __user *)arg, sizeof(*params));
 		if (IS_ERR(params))
-			return PTR_ERR(params);
+			return PTR_ERR(no_free_ptr(params));
 
 		retval = snd_compress_check_input(params);
 		if (retval)
-			goto out;
+			return retval;
 
 		retval = snd_compr_allocate_buffer(stream, params);
-		if (retval) {
-			retval = -ENOMEM;
-			goto out;
-		}
+		if (retval)
+			return -ENOMEM;
 
 		retval = stream->ops->set_params(stream, params);
 		if (retval)
-			goto out;
+			return retval;
 
 		if (stream->next_track)
-			goto out;
+			return retval;
 
 		stream->metadata_set = false;
 		stream->next_track = false;
@@ -622,15 +617,13 @@ snd_compr_set_params(struct snd_compr_stream *stream, unsigned long arg)
 	} else {
 		return -EPERM;
 	}
-out:
-	kfree(params);
 	return retval;
 }
 
 static int
 snd_compr_get_params(struct snd_compr_stream *stream, unsigned long arg)
 {
-	struct snd_codec *params;
+	struct snd_codec *params __free(kfree) = NULL;
 	int retval;
 
 	if (!stream->ops->get_params)
@@ -641,12 +634,9 @@ snd_compr_get_params(struct snd_compr_stream *stream, unsigned long arg)
 		return -ENOMEM;
 	retval = stream->ops->get_params(stream, params);
 	if (retval)
-		goto out;
+		return retval;
 	if (copy_to_user((char __user *)arg, params, sizeof(*params)))
-		retval = -EFAULT;
-
-out:
-	kfree(params);
+		return -EFAULT;
 	return retval;
 }