From: Andi Kleen <ak@suse.de>
To: eranian@hpl.hp.com
Subject: Re: [PATCH 10/18] 2.6.17.9 perfmon2 patch for review: PMU context switch support
Date: Fri, 25 Aug 2006 15:17:30 +0200
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Cc: linux-kernel@vger.kernel.org, "S. P. Prasanna" <prasanna@in.ibm.com>
References: <200608230806.k7N86151000456@frankl.hpl.hp.com> <200608251420.31564.ak@suse.de> <20060825125633.GE5330@frankl.hpl.hp.com>
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On Friday 25 August 2006 14:56, Stephane Eranian wrote:
> On Fri, Aug 25, 2006 at 02:20:31PM +0200, Andi Kleen wrote:
> > On Friday 25 August 2006 13:56, Stephane Eranian wrote:
> > 
> > > > I suppose some of those functions must be marked __kprobes
> > > >  
> > > Are there any guidelines as to why some functions must be ignored
> > > by kprobes? I assume if meaans they cannot be instrumented.
> > 
> > It does yes.
> > 
> > In general anything that could cause kprobes to recurse is forbidden.
> 
> In the case of the PMU context switch, are you saying that you may
> context switch as a consequence of hitting a (K)probe?

I hope not, but at least the current __switch_to is marked __kprobes
and I assume there was some reason for it and it will likely apply
to callees too. For details ask Prasanna (cc'ed).

-Andi
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