[alsa-devel] [PATCH] Fix Jack plugin

[Adrian Knoth]

On 08/04/2011 07:35 AM, Kevin Ross wrote:

> I've uploaded a patch to ticket 2727, at 
> https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2727
> 
> The symptom:  Using the Jack plugin causes whatever program is 
> outputting audio to hang after about 10-20 seconds.
> 
> The cause: The plugin creates a pipe, so that the fd's could be polled 
> to indicate completion of a transfer.  However, the call to write() 
> blocks when playing audio, as nothing actually reads from the pipe, and 
> it fills up until it blocks.
> 
> The patch:
> 
> --- alsa-plugins-1.0.23/jack/pcm_jack.c 2010-04-16 04:11:10.000000000 -0700
> +++ alsa-plugins-1.0.23.new/jack/pcm_jack.c     2011-08-03 
> 21:54:51.795378947 -0700
> @@ -307,6 +308,18 @@
>          return 0;
>   }
> 
> +static int make_nonblock(int fd) {
> +       int fl;
> +
> +       if ((fl = fcntl(fd, F_GETFL)) < 0)
> +               return fl;
> +
> +       if (fl & O_NONBLOCK)
> +               return 0;
> +
> +       return fcntl(fd, F_SETFL, fl | O_NONBLOCK);
> +}
> +
>   static int snd_pcm_jack_open(snd_pcm_t **pcmp, const char *name,
>                               snd_config_t *playback_conf,
>                               snd_config_t *capture_conf,
> @@ -363,6 +376,9 @@
> 
>          socketpair(AF_LOCAL, SOCK_STREAM, 0, fd);
> 
> +       make_nonblock(fd[0]);
> +       make_nonblock(fd[1]);
> +
>          jack->fd = fd[0];
> 
>          jack->io.version = SND_PCM_IOPLUG_VERSION;

Confirmed to be working. I'm going to send a git patch ASAP.



Cheers