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From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Ingo Molnar <mingo@elte.hu>
Subject: Re: [RFC][PATCH] PM: Warn if interrupts are enabled during suspend-resume of sysdevs
Date: Sun, 5 Apr 2009 19:39:29 +0200
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Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, Len Brown <lenb@kernel.org>,
       pm list <linux-pm@lists.linux-foundation.org>,
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On Sunday 05 April 2009, Ingo Molnar wrote:
> 
> * Rafael J. Wysocki <rjw@sisk.pl> wrote:
> 
> > From: Rafael J. Wysocki <rjw@sisk.pl>
> > 
> > Sysdev have to be suspended and resumed with interrupts disabled 
> > and things usually break in a way that's difficult to debug if one 
> > of sysdev drivers enables interrupts by mistake during suspend or 
> > resume.  Add extra checks that will generate warnings in such 
> > cases.
> 
> no objections - but obviously the real solution would be to finish 
> PeterZ's "detect assymetric kernel functions" patch:
> 
> That patch (Peter posted an initial version of it already on lkml) 
> works the following way:
> 
> the ftrace function-graph-tracer plugin is utilized to instrument 
> every function call in the kernel. That is extended with the 
> following check: every function except __lockfunc and __sched 
> functions must be 'balanced' - i.e. they must enter and exit with 
> the same IRQ flags, preempt count and lock depth counter.

Nothing wrong with that, but I'd also like to have checks that don't depend on
ftrace. :-)

Thanks,
Rafael