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From: John Baldwin <jhb@freebsd.org>
To: Andriy Gapon <avg@freebsd.org>
Date: Thu, 1 Dec 2011 13:49:50 -0500
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	(bigwig.baldwin.cx); Thu, 01 Dec 2011 13:49:51 -0500 (EST)
Cc: freebsd-current@freebsd.org
Subject: Re: Stop scheduler on panic
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On Thursday, December 01, 2011 11:59:10 am Andriy Gapon wrote:
> 
> [cc list trimmed]
> 
> on 21/11/2011 18:32 John Baldwin said the following:
> > On Friday, November 18, 2011 4:59:32 pm Andriy Gapon wrote:
> >> on 17/11/2011 23:38 John Baldwin said the following:
> >>> On Thursday, November 17, 2011 4:35:07 pm John Baldwin wrote:
> >>>> Hmmm, you could also make critical_exit() not perform deferred preemptions
> >>>> if SCHEDULER_STOPPED?  That would fix the recursion and still let the
> >>>> preemption "work" when resuming from the debugger?
> 
> 
> Just to clarify, probably you are actually suggesting to not perform deferred
> preemptions if kdb_active == TRUE.  Because that's where we get the recursion (via
> kdb_switch).
> 
> I think that if we get into the mi_switch in a state where !kdb_active &&
> SCHEDULER_STOPPED(), then we probably should just - I don't know - panic again?
> 
> [the following is preserved for context]

Hmmm.  I'd be tempted to just ignore pending preemptions anytime
SCHEDULER_STOPPED() is true.  If it's stopped for a reason other than being
in the debugger (e.g. panic), I'd rather make a best effort at getting a dump
than panic again.

-- 
John Baldwin