Bug #952 - MIDI lockup

Bug #952 - MIDI lockup

[Lee Revell]

Can someone take a quick look at:

https://bugtrack.alsa-project.org/alsa-bug/view.php?id=952

There is a nice screenshot of the kernel panic.  The bug has been
verified with ALSA 1.0.12-rc1.

It seems to crash while taking a spinlock in snd_timer_interrupt when
called from rtc_interrupt - maybe the changes to the ALSA RTC timer a
few months ago are involved?

Lee


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Re: Bug #952 - MIDI lockup

[Takashi Iwai]

At Sun, 02 Jul 2006 18:45:59 -0400,
Lee Revell wrote:
> 
> Can someone take a quick look at:
> 
> https://bugtrack.alsa-project.org/alsa-bug/view.php?id=952
> 
> There is a nice screenshot of the kernel panic.  The bug has been
> verified with ALSA 1.0.12-rc1.
> 
> It seems to crash while taking a spinlock in snd_timer_interrupt when
> called from rtc_interrupt - maybe the changes to the ALSA RTC timer a
> few months ago are involved?

Does the patch below fix?


Takashi


diff -r 0dc0bac494b6 core/timer.c
--- a/core/timer.c	Mon Jul 03 16:38:28 2006 +0200
+++ b/core/timer.c	Mon Jul 03 17:56:22 2006 +0200
@@ -628,8 +628,9 @@ static void snd_timer_tasklet(unsigned l
 	struct snd_timer_instance *ti;
 	struct list_head *p;
 	unsigned long resolution, ticks;
-
-	spin_lock(&timer->lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&timer->lock, flags);
 	/* now process all callbacks */
 	while (!list_empty(&timer->sack_list_head)) {
 		p = timer->sack_list_head.next;		/* get first item */
@@ -649,7 +650,7 @@ static void snd_timer_tasklet(unsigned l
 		spin_lock(&timer->lock);
 		ti->flags &= ~SNDRV_TIMER_IFLG_CALLBACK;
 	}
-	spin_unlock(&timer->lock);
+	spin_unlock_irqrestore(&timer->lock, flags);
 }
 
 /*

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Re: Bug #952 - MIDI lockup

[Lee Revell]

On Mon, 2006-07-03 at 17:56 +0200, Takashi Iwai wrote:
> At Sun, 02 Jul 2006 18:45:59 -0400,
> Lee Revell wrote:
> > 
> > Can someone take a quick look at:
> > 
> > https://bugtrack.alsa-project.org/alsa-bug/view.php?id=952
> > 
> > There is a nice screenshot of the kernel panic.  The bug has been
> > verified with ALSA 1.0.12-rc1.
> > 
> > It seems to crash while taking a spinlock in snd_timer_interrupt when
> > called from rtc_interrupt - maybe the changes to the ALSA RTC timer a
> > few months ago are involved?
> 
> Does the patch below fix?
> 

Looks like it might.  I could not reproduce the problem myself but I've
attached it to the bug report for testing.

Lee


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Re: Bug #952 - MIDI lockup

[Lee Revell]

On Mon, 2006-07-03 at 17:56 +0200, Takashi Iwai wrote:
> At Sun, 02 Jul 2006 18:45:59 -0400,
> Lee Revell wrote:
> > 
> > Can someone take a quick look at:
> > 
> > https://bugtrack.alsa-project.org/alsa-bug/view.php?id=952
> > 
> > There is a nice screenshot of the kernel panic.  The bug has been
> > verified with ALSA 1.0.12-rc1.
> > 
> > It seems to crash while taking a spinlock in snd_timer_interrupt when
> > called from rtc_interrupt - maybe the changes to the ALSA RTC timer a
> > few months ago are involved?
> 
> Does the patch below fix?

No.

Lee


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Re: Bug #952 - MIDI lockup

[Takashi Iwai]

At Tue, 04 Jul 2006 11:00:40 -0400,
Lee Revell wrote:
> 
> On Mon, 2006-07-03 at 17:56 +0200, Takashi Iwai wrote:
> > At Sun, 02 Jul 2006 18:45:59 -0400,
> > Lee Revell wrote:
> > > 
> > > Can someone take a quick look at:
> > > 
> > > https://bugtrack.alsa-project.org/alsa-bug/view.php?id=952
> > > 
> > > There is a nice screenshot of the kernel panic.  The bug has been
> > > verified with ALSA 1.0.12-rc1.
> > > 
> > > It seems to crash while taking a spinlock in snd_timer_interrupt when
> > > called from rtc_interrupt - maybe the changes to the ALSA RTC timer a
> > > few months ago are involved?
> > 
> > Does the patch below fix?
> 
> No.

Pointer?  The test in bug #952 seems inaccurate.


Takashi

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Re: Bug #952 - MIDI lockup

[Lee Revell]

On Tue, 2006-07-04 at 17:32 +0200, Takashi Iwai wrote:
> At Tue, 04 Jul 2006 11:00:40 -0400,
> Lee Revell wrote:
> > 
> > On Mon, 2006-07-03 at 17:56 +0200, Takashi Iwai wrote:
> > > At Sun, 02 Jul 2006 18:45:59 -0400,
> > > Lee Revell wrote:
> > > > 
> > > > Can someone take a quick look at:
> > > > 
> > > > https://bugtrack.alsa-project.org/alsa-bug/view.php?id=952
> > > > 
> > > > There is a nice screenshot of the kernel panic.  The bug has been
> > > > verified with ALSA 1.0.12-rc1.
> > > > 
> > > > It seems to crash while taking a spinlock in snd_timer_interrupt when
> > > > called from rtc_interrupt - maybe the changes to the ALSA RTC timer a
> > > > few months ago are involved?
> > > 
> > > Does the patch below fix?
> > 
> > No.
> 
> Pointer?  The test in bug #952 seems inaccurate.

Hmm, it might have fixed it.  I think the user did not test correctly.

Lee


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Re: Bug #952 - MIDI lockup

[Lee Revell]

On Tue, 2006-07-04 at 17:32 +0200, Takashi Iwai wrote:
> At Tue, 04 Jul 2006 11:00:40 -0400,
> Lee Revell wrote:
> > 
> > On Mon, 2006-07-03 at 17:56 +0200, Takashi Iwai wrote:
> > > At Sun, 02 Jul 2006 18:45:59 -0400,
> > > Lee Revell wrote:
> > > > 
> > > > Can someone take a quick look at:
> > > > 
> > > > https://bugtrack.alsa-project.org/alsa-bug/view.php?id=952
> > > > 
> > > > There is a nice screenshot of the kernel panic.  The bug has been
> > > > verified with ALSA 1.0.12-rc1.
> > > > 
> > > > It seems to crash while taking a spinlock in snd_timer_interrupt when
> > > > called from rtc_interrupt - maybe the changes to the ALSA RTC timer a
> > > > few months ago are involved?
> > > 
> > > Does the patch below fix?
> > 
> > No.
> 
> Pointer?  The test in bug #952 seems inaccurate.

OK, the patch does fix the problem.  Please apply.

Lee


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Re: Bug #952 - MIDI lockup

[Takashi Iwai]

At Wed, 05 Jul 2006 11:08:15 -0400,
Lee Revell wrote:
> 
> On Tue, 2006-07-04 at 17:32 +0200, Takashi Iwai wrote:
> > At Tue, 04 Jul 2006 11:00:40 -0400,
> > Lee Revell wrote:
> > > 
> > > On Mon, 2006-07-03 at 17:56 +0200, Takashi Iwai wrote:
> > > > At Sun, 02 Jul 2006 18:45:59 -0400,
> > > > Lee Revell wrote:
> > > > > 
> > > > > Can someone take a quick look at:
> > > > > 
> > > > > https://bugtrack.alsa-project.org/alsa-bug/view.php?id=952
> > > > > 
> > > > > There is a nice screenshot of the kernel panic.  The bug has been
> > > > > verified with ALSA 1.0.12-rc1.
> > > > > 
> > > > > It seems to crash while taking a spinlock in snd_timer_interrupt when
> > > > > called from rtc_interrupt - maybe the changes to the ALSA RTC timer a
> > > > > few months ago are involved?
> > > > 
> > > > Does the patch below fix?
> > > 
> > > No.
> > 
> > Pointer?  The test in bug #952 seems inaccurate.
> 
> OK, the patch does fix the problem.  Please apply.

Thanks for the confirmation.  Committed to HG repo.


Takashi

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