[alsa-devel] [PATCH] PCM: snd_pcm_dmix_drain() maybe blocked after suspend and resume

[Takashi Iwai]

At Mon, 8 Jun 2015 17:38:11 +0800,
Shengjiu Wang wrote:
> 
> After suspend and resume, the alsa driver is stopped. But if alsa-lib run
> into snd_pcm_dmix_drain(), it need to wait avail >= pcm->stop_threshold,
> otherwise, it will not exit the loop, so finally it is blocked at poll() of
> snd_pcm_wait_nocheck(pcm, -1).
> This patch is to add state check after snd_pcm_wait_nocheck(pcm, -1), if
> the state is SND_PCM_STATE_SUSPENDED, then return error.
> 
> Signed-off-by: Shengjiu Wang <shengjiu.wang at freescale.com>
> ---
>  src/pcm/pcm_dmix.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/src/pcm/pcm_dmix.c b/src/pcm/pcm_dmix.c
> index babde6a..0cc318e 100644
> --- a/src/pcm/pcm_dmix.c
> +++ b/src/pcm/pcm_dmix.c
> @@ -647,6 +647,12 @@ static int snd_pcm_dmix_drain(snd_pcm_t *pcm)
>  		if (dmix->state == SND_PCM_STATE_DRAINING) {
>  			snd_pcm_dmix_sync_area(pcm);
>  			snd_pcm_wait_nocheck(pcm, -1);
> +			switch (snd_pcm_state(pcm)) {

It's better (shorter) to call snd_pcm_state(dmix->spcm) in this case.

And, I think we should have the check of SND_PCM_STATE_SUSPENDED at
the beginning of snd_pcm_dmix_drain() before entering to the loop,
too.

Last but not least, the very same bug is present for dshare.  Could
you fix this together?


thanks,

Takashi

> +			case SND_PCM_STATE_SUSPENDED:
> +				return -ESTRPIPE;
> +			default:
> +				break;
> +			}
>  			snd_pcm_direct_clear_timer_queue(dmix); /* force poll to wait */
>  		}
>  	} while (dmix->state == SND_PCM_STATE_DRAINING);
> -- 
> 1.7.9.5
>