5.2.1-RC hangs occasionally when sound files are played using the pcm driver

[Brian O'Shea]

Sorry for the late response on this.  I've been trying various combinations
of kernel options in an attempt to narrow down the problem.

--- Don Lewis <truckman at FreeBSD.org> wrote:
> On 23 Feb, Brian O'Shea wrote:
> > --- Don Lewis <truckman at FreeBSD.org> wrote:
> >> 
> >> The cause of deadlocks is more likely to be caught by WITNESS.  In this
> > 
> > With WITNESS the hang still occurrs, and still no panic.  It's hard to
> > tell since the problem tends to happen at random times, but it seems like
> > it happens more quickly with the kernel that has WITNESS and INVARIANTS
> > enabled.
> 
> Can you see any kernel diagnostic messages, or are you running X?  If
> you are running X, can you set up a serial console, or can you reproduce
> the hang while switched to a text console?

I was able to reproduce the problem from a text console, and there were
no diagnostic messages when the problem happened, even with the WITNESS
code enabled.  However, I think I have narrowed the problem down to the
SMP kernel where it happens reliably.  I have not observed the problem
at all on a UP kernel.

> Depending on the cause of the problem, you might need to build a kernel
> with DDB support and break into DDB from the console while the machine
> is hung to figure out the cause.

I will try this.

> > I'd be willing to test your patch, if that would help.  Where can I
> > find it?
> 
> The patch below should be applied to a recent version of -CURRENT.

At the moment I don't have a -CURRENT system.  It might make more sense
for me to try to debug this on a scratch system, instead of on the machine
that I rely on.  I'll try to cobble something together from scraps, and
keep you posted.

Thanks,
-brian

> Index: sys/dev/sound/pcm/dsp.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/dev/sound/pcm/dsp.c,v
> retrieving revision 1.73
> diff -u -r1.73 dsp.c
...


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