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Date: Thu, 10 Jun 2010 11:34:33 -0400 From: Jason Baron <jbaron@...hat.com> To: Frederic Weisbecker <fweisbec@...il.com> Cc: linux-kernel@...r.kernel.org, mingo@...e.hu, mathieu.desnoyers@...ymtl.ca, hpa@...or.com, tglx@...utronix.de, rostedt@...dmis.org, andi@...stfloor.org, roland@...hat.com, rth@...hat.com, mhiramat@...hat.com, avi@...hat.com, davem@...emloft.net, vgoyal@...hat.com, sam@...nborg.org Subject: Re: [PATCH 01/13] jump label v9: notifier atomic call chain notrace On Wed, Jun 09, 2010 at 11:58:13PM +0200, Frederic Weisbecker wrote: > On Wed, Jun 09, 2010 at 05:38:52PM -0400, Jason Baron wrote: > > From: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca> > > > > In LTTng, being able to use the atomic notifier from cpu idle entry to > > ensure the tracer flush the last events in the current subbuffer > > requires the rcu read-side to be marked "notrace", otherwise it can end > > up calling back into lockdep and the tracer. > > > > Also apply to the the die notifier. > > > > Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca> > > Signed-off-by: Jason Baron <jbaron@...hat.com> > > Reviewed-by: Masami Hiramatsu <mhiramat@...hat.com> > > --- > > > > I don't understand the purpose of this patch. The only notifier > I see that is used by jmp label is the module notifier, and I > don't see how it can do bad things if we don't use the notrace > version. > hmmm...yeah, this patch was introduced b/c of the use of the 'int3' notifier when updating the kernel text. We got into a recursive loop without it. However, since the current implementation is using stop_machine() to do text updates, I don't think this patch is necessary until we have the more optimal text updating mechanism in place. I'll re-test without this patch. thanks, -Jason -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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