[ 3.8.y.z extended stable ] Patch "ALSA: seq-oss: Initialize MIDI clients asynchronously" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Mon Jul 29 17:32:01 UTC 2013


On Mon, 2013-07-29 at 16:21 +0200, Takashi Iwai wrote:
> At Thu, 25 Jul 2013 12:29:00 -0700,
> Kamal Mostafa wrote:
> > 
> > This is a note to let you know that I have just added a patch titled
> > 
> >     ALSA: seq-oss: Initialize MIDI clients asynchronously
> > 
> > to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
> > which can be found at:
> > 
> >  http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue
> > 
> > This patch is scheduled to be released in version 3.8.13.6.
> > 
> > If you, or anyone else, feels it should not be added to this tree, please 
> > reply to this email.
> 
> This patch isn't needed for 3.8.x unless someone actually hits the
> problem.  The problem was reported first for 3.10 kernel.


Hi Takashi-

This one looks to me like a good fix for 3.8 anyway -- is there a reason
why it specifically shouldn't go into 3.8.y-stable?

Per your request, I have dropped it from the linux-3.8.y-queue, but I'd
be happy to re-apply it if you change your mind.  :-)

Thanks,

 -Kamal



> > ------
> > 
> > >From 2e602e4007d29e182ac090df7d0c9fb72018c35f Mon Sep 17 00:00:00 2001
> > From: Takashi Iwai <tiwai at suse.de>
> > Date: Tue, 16 Jul 2013 12:17:49 +0200
> > Subject: ALSA: seq-oss: Initialize MIDI clients asynchronously
> > 
> > commit 256ca9c3ad5013ff8a8f165e5a82fab437628c8e upstream.
> > 
> > We've got bug reports that the module loading stuck on Debian system
> > with 3.10 kernel.  The debugging session revealed that the initial
> > registration of OSS sequencer clients stuck at module loading time,
> > which involves again with request_module() at the init phase.  This is
> > triggered only by special --install stuff Debian is using, but it's
> > still not good to have such loops.
> > 
> > As a workaround, call the registration part asynchronously.  This is a
> > better approach irrespective of the hang fix, in anyway.
> > 
> > Reported-and-tested-by: Philipp Matthias Hahn <pmhahn at pmhahn.de>
> > Signed-off-by: Takashi Iwai <tiwai at suse.de>
> > Signed-off-by: Kamal Mostafa <kamal at canonical.com>
> > ---
> >  sound/core/seq/oss/seq_oss_init.c | 16 +++++++++++++---
> >  sound/core/seq/oss/seq_oss_midi.c |  2 +-
> >  2 files changed, 14 insertions(+), 4 deletions(-)
> > 
> > diff --git a/sound/core/seq/oss/seq_oss_init.c b/sound/core/seq/oss/seq_oss_init.c
> > index e3cb46f..b3f39b5 100644
> > --- a/sound/core/seq/oss/seq_oss_init.c
> > +++ b/sound/core/seq/oss/seq_oss_init.c
> > @@ -31,6 +31,7 @@
> >  #include <linux/export.h>
> >  #include <linux/moduleparam.h>
> >  #include <linux/slab.h>
> > +#include <linux/workqueue.h>
> > 
> >  /*
> >   * common variables
> > @@ -60,6 +61,14 @@ static void free_devinfo(void *private);
> >  #define call_ctl(type,rec) snd_seq_kernel_client_ctl(system_client, type, rec)
> > 
> > 
> > +/* call snd_seq_oss_midi_lookup_ports() asynchronously */
> > +static void async_call_lookup_ports(struct work_struct *work)
> > +{
> > +	snd_seq_oss_midi_lookup_ports(system_client);
> > +}
> > +
> > +static DECLARE_WORK(async_lookup_work, async_call_lookup_ports);
> > +
> >  /*
> >   * create sequencer client for OSS sequencer
> >   */
> > @@ -85,9 +94,6 @@ snd_seq_oss_create_client(void)
> >  	system_client = rc;
> >  	debug_printk(("new client = %d\n", rc));
> > 
> > -	/* look up midi devices */
> > -	snd_seq_oss_midi_lookup_ports(system_client);
> > -
> >  	/* create annoucement receiver port */
> >  	memset(port, 0, sizeof(*port));
> >  	strcpy(port->name, "Receiver");
> > @@ -115,6 +121,9 @@ snd_seq_oss_create_client(void)
> >  	}
> >  	rc = 0;
> > 
> > +	/* look up midi devices */
> > +	schedule_work(&async_lookup_work);
> > +
> >   __error:
> >  	kfree(port);
> >  	return rc;
> > @@ -160,6 +169,7 @@ receive_announce(struct snd_seq_event *ev, int direct, void *private, int atomic
> >  int
> >  snd_seq_oss_delete_client(void)
> >  {
> > +	cancel_work_sync(&async_lookup_work);
> >  	if (system_client >= 0)
> >  		snd_seq_delete_kernel_client(system_client);
> > 
> > diff --git a/sound/core/seq/oss/seq_oss_midi.c b/sound/core/seq/oss/seq_oss_midi.c
> > index 677dc84..862d8489 100644
> > --- a/sound/core/seq/oss/seq_oss_midi.c
> > +++ b/sound/core/seq/oss/seq_oss_midi.c
> > @@ -72,7 +72,7 @@ static int send_midi_event(struct seq_oss_devinfo *dp, struct snd_seq_event *ev,
> >   * look up the existing ports
> >   * this looks a very exhausting job.
> >   */
> > -int __init
> > +int
> >  snd_seq_oss_midi_lookup_ports(int client)
> >  {
> >  	struct snd_seq_client_info *clinfo;
> > --
> > 1.8.1.2
> > 
> 

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