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Bug#560212: alsa-source: Driver snd-hrtimer - causing system freeze with Rosegarden

Przemysław Pawełczyk wrote:
> Wojtek Zabolotny wrote:

>> When I try to use the "HR timer" as a MIDI sequencer timer in the
>> Rosegarden (http://www.rosegardenmusic.com) application, the system
>> freezes.
> Just for the record: The problem still exists in current wheezy.
> linux-image-3.1.0-1-amd64 3.1.6-1
> rosegarden 1:11.11.11-1
> alsa-base 1.0.23+dfsg-4
> libasound2

Hm.  The following patch was included in v2.6.33:

| commit fcfdebe70759
| Author: Takashi Iwai <tiwai@suse.de>
| Date:   Fri Dec 11 12:51:05 2009 +0100
|     ALSA: hrtimer - Fix lock-up
|     The timer stop callback can be called from snd_timer_interrupt(), which
|     is called from the hrtimer callback.  Since hrtimer_cancel() waits for
|     the callback completion, this eventually results in a lock-up.
|     This patch fixes the problem by just toggling a flag at stop callback
|     and call hrtimer_cancel() later.
|     Reported-and-tested-by: Wojtek Zabolotny <W.Zabolotny@elka.pw.edu.pl>
|     Cc: <stable@kernel.org>
|     Signed-off-by: Takashi Iwai <tiwai@suse.de>

Based on the description, it seems that Wojtek tested that, and the
patch was backported to 2.6.32.y, so I'm tempted to close this bug
(though it would be nice to have confirmation from him either way).

Could you file a separate bug?

If you have time, the next step would be to write a summary of the
problem (including exact steps to reproduce it) to the
alsa-devel@alsa-project.org list, cc-ing Clemens Ladisch
<clemens@ladisch.de> and me or the bug log so we can track it.  The
alsa-info.sh[1] script might be useful when doing so to tell upstream
what hardware and software you're using.

They might say, "oh, right.  that bug." and provide us with lots of
advice towards fixing it. :)  Or maybe they'll have questions.

Thanks and hope that helps,

[1] http://www.alsa-project.org/alsa-info.sh

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