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

[Takashi Iwai]

At Mon, 29 Jul 2013 10:32:01 -0700,
Kamal Mostafa wrote:
> 
> 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?

Because there is no problem to fix in 3.8 kernel :)


Takashi

> 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
> > > 
> > 
>