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Subject: Re: [PATCH 01/10] perf, trace: Remove IRQ-disable from
 perf/tracepoint interaction
From: Steven Rostedt <rostedt@goodmis.org>
Reply-To: rostedt@goodmis.org
To: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, Ingo Molnar <mingo@elte.hu>,
       Paul Mackerras <paulus@samba.org>,
       Arnaldo Carvalho de Melo <acme@infradead.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <y0maartf8ve.fsf@fche.csb>
References: <20100521090201.326791353@chello.nl>
	 <20100521090710.419716197@chello.nl>  <y0maartf8ve.fsf@fche.csb>
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Organization: Kihon Technologies Inc.
Date: Fri, 21 May 2010 13:53:00 -0400
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On Fri, 2010-05-21 at 13:43 -0400, Frank Ch. Eigler wrote:
> Peter Zijlstra <a.p.zijlstra@chello.nl> writes:
> 
> > [...]
> > @@ -799,13 +799,10 @@ perf_trace_templ_##call(struct ftrace_ev
> >  static notrace void perf_trace_##call(proto)				\
> >  {									\
> >  	struct ftrace_event_call *event_call = &event_##call;		\
> > -	struct pt_regs *__regs = &get_cpu_var(perf_trace_regs);		\
> > -									\
> > -	perf_fetch_caller_regs(__regs, 1);				\
> > -									\
> > -	perf_trace_templ_##template(event_call, __regs, args);		\
> > +	struct pt_regs __regs;						\
> >  									\
> > -	put_cpu_var(perf_trace_regs);					\
> > +	perf_fetch_caller_regs(&__regs, 1);				\
> > +	perf_trace_templ_##template(event_call, &__regs, args);		\
> >  }
> >  [...]
> 
> To what extent are you worried about something the size of struct
> pt_regs being auto/stack allocated?

Isn't pt_regs already allocated on the stack when interrupted?

-- Steve