[alsa-devel] [PATCH] compress: add support for gapless playback

[Takashi Iwai]

At Wed, 13 Feb 2013 08:00:34 -0800,
Vinod Koul wrote:
> 
> +static int
> +snd_compr_get_metadata(struct snd_compr_stream *stream, unsigned long arg)
> +{
> +	struct snd_compr_metadata *metadata;
> +	int retval;
> +
> +	if (!stream->ops->get_metadata)
> +		return -ENXIO;
> +
> +	metadata = kmalloc(sizeof(*metadata), GFP_KERNEL);

There is no merit to use kmalloc just for two integers at all.
Simply put on stack:
	struct snd_compr_metadata metdata;
	if (copy_from_user(&metadata, (void __user *)arg, sizeof(metadata)))
	...

Ditto for snd_compr_set_metadata().

> +static int snd_compr_partial_drain(struct snd_compr_stream *stream)
> +{
> +	int retval;
> +	if (stream->runtime->state == SNDRV_PCM_STATE_PREPARED ||
> +			stream->runtime->state == SNDRV_PCM_STATE_SETUP)
> +		return -EPERM;
> +	/* stream can be drained only when next track has been signalled */
> +	if (stream->next_track == false)
> +		return -EPERM;
> +
> +	retval = stream->ops->trigger(stream, SND_COMPR_TRIGGER_PARTIAL_DRAIN);
> +	if (retval)
> +		pr_err("Partial drain returned failure\n");

I don't think it's good to spew errors.

Also, the initialization of new stream fields is missing in other
places like prepare callback?  Otherwise the values will retain.


thanks,

Takashi