[alsa-devel] [PATCH] Tell user that stream to be rewound is suspended

[Takashi Iwai]

At Sun,  2 Aug 2009 18:14:44 +0200,
Lubomir Rintel wrote:
> 
> Return STRPIPE instead of EBADF when userspace attempts to rewind
> of forward a stream that was suspended in meanwhile, so that it
> can be recovered by snd_pcm_recover().
> 
> This was causing Pulseaudio to unload the ALSA sink module under a race
> condition when it attempted to rewind the stream right after resume from
> suspend, before writing to the stream which would cause it to revive the
> stream otherwise. Tested to work with Pulseaudio patched to attempt to
> snd_pcm_recover() upon receiving an error from snd_pcm_rewind().
> 
> Signed-off-by: Lubomir Rintel <lkundrak at v3.sk>

The change looks fine, but I think this isn't for stable kernel since
this is actually an ABI extension.

For testing, I'm going to apply this to sound-unstable tree for the
time being.  I'll merge to the main sound tree soon later, though.


thanks,

Takashi

> ---
>  sound/core/pcm_native.c |   12 ++++++++++++
>  1 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> index ac2150e..d89c816 100644
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -2208,6 +2208,9 @@ static snd_pcm_sframes_t snd_pcm_playback_rewind(struct snd_pcm_substream *subst
>  	case SNDRV_PCM_STATE_XRUN:
>  		ret = -EPIPE;
>  		goto __end;
> +	case SNDRV_PCM_STATE_SUSPENDED:
> +		ret = -ESTRPIPE;
> +		goto __end;
>  	default:
>  		ret = -EBADFD;
>  		goto __end;
> @@ -2253,6 +2256,9 @@ static snd_pcm_sframes_t snd_pcm_capture_rewind(struct snd_pcm_substream *substr
>  	case SNDRV_PCM_STATE_XRUN:
>  		ret = -EPIPE;
>  		goto __end;
> +	case SNDRV_PCM_STATE_SUSPENDED:
> +		ret = -ESTRPIPE;
> +		goto __end;
>  	default:
>  		ret = -EBADFD;
>  		goto __end;
> @@ -2299,6 +2305,9 @@ static snd_pcm_sframes_t snd_pcm_playback_forward(struct snd_pcm_substream *subs
>  	case SNDRV_PCM_STATE_XRUN:
>  		ret = -EPIPE;
>  		goto __end;
> +	case SNDRV_PCM_STATE_SUSPENDED:
> +		ret = -ESTRPIPE;
> +		goto __end;
>  	default:
>  		ret = -EBADFD;
>  		goto __end;
> @@ -2345,6 +2354,9 @@ static snd_pcm_sframes_t snd_pcm_capture_forward(struct snd_pcm_substream *subst
>  	case SNDRV_PCM_STATE_XRUN:
>  		ret = -EPIPE;
>  		goto __end;
> +	case SNDRV_PCM_STATE_SUSPENDED:
> +		ret = -ESTRPIPE;
> +		goto __end;
>  	default:
>  		ret = -EBADFD;
>  		goto __end;
> -- 
> 1.6.2.5
>