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

[Luis Henriques]

Takashi Iwai <tiwai at suse.de> writes:

> At Wed, 24 Jul 2013 10:12:09 +0100,
> Luis Henriques 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-3.5.y-queue branch of the 3.5.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-3.5.y-queue
>> 
>> If you, or anyone else, feels it should not be added to this tree, please 
>> reply to this email.
>> 
>> For more information about the 3.5.y.z tree, see
>> https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
>
> This problem was reported to appear since 3.10, so no need to patch
> older kernels, although it's not that bad to apply it.
>
>
> Takashi
>

Thank you for your feedback.  I'll drop this patch from the 3.5 queue.

Cheers,
-- 
Luis

>> 
>> Thanks.
>> -Luis
>> 
>> ------
>> 
>> >From 84d0ac92d9bc06b1a5a6df8b12c44e2ab47249df Mon Sep 17 00:00:00 2001
>> From: Takashi Iwai <tiwai at suse.de>
>> Date: Tue, 16 Jul 2013 12:17:49 +0200
>> Subject: [PATCH] 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: Luis Henriques <luis.henriques 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
>>