Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932313Ab0FJPfQ (ORCPT ); Thu, 10 Jun 2010 11:35:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6884 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751893Ab0FJPfM (ORCPT ); Thu, 10 Jun 2010 11:35:12 -0400 Date: Thu, 10 Jun 2010 11:34:33 -0400 From: Jason Baron To: Frederic Weisbecker Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, mathieu.desnoyers@polymtl.ca, hpa@zytor.com, tglx@linutronix.de, rostedt@goodmis.org, andi@firstfloor.org, roland@redhat.com, rth@redhat.com, mhiramat@redhat.com, avi@redhat.com, davem@davemloft.net, vgoyal@redhat.com, sam@ravnborg.org Subject: Re: [PATCH 01/13] jump label v9: notifier atomic call chain notrace Message-ID: <20100610153432.GB3923@redhat.com> References: <20100609215810.GA12752@nowhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100609215810.GA12752@nowhere> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1550 Lines: 39 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 > > > > 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 > > Signed-off-by: Jason Baron > > Reviewed-by: Masami Hiramatsu > > --- > > > > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/