From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756224Ab3HaUkN (ORCPT ); Sat, 31 Aug 2013 16:40:13 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:25202 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754077Ab3HaUkL (ORCPT ); Sat, 31 Aug 2013 16:40:11 -0400 X-Authority-Analysis: v=2.0 cv=fJG7LOme c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=ZnFBpunljT8A:10 a=5SG0PmZfjMsA:10 a=IkcTkHD0fZMA:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=QYmdpx3kvKkA:10 a=VnNF1IyMAAAA:8 a=hCKiQadejs-moRHCX5cA:9 a=QEXdDO2ut3YA:10 a=jeBq3FmKZ4MA:10 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Subject: Re: [RFC][PATCH 11/18 v2] ftrace: Adde infrastructure to stop RCU unsafe checker from checking From: Steven Rostedt To: paulmck@linux.vnet.ibm.com Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Peter Zijlstra , Frederic Weisbecker , Jiri Olsa In-Reply-To: <20130831195258.GQ3871@linux.vnet.ibm.com> References: <20130831051117.884125230@goodmis.org> <20130831051702.253028770@goodmis.org> <20130831195258.GQ3871@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Date: Sat, 31 Aug 2013 16:40:04 -0400 Message-ID: <1377981604.26624.4.camel@pippen.local.home> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2013-08-31 at 12:52 -0700, Paul E. McKenney wrote: > On Sat, Aug 31, 2013 at 01:11:28AM -0400, Steven Rostedt wrote: > > From: "Steven Rostedt (Red Hat)" > > > > This is a light weight way to keep the rcu checker from checking > > RCU safety. It adds a ftrace_unsafe_rcu_checker_disable/enable() > > that increments or decrements a counter respectively. When the > > counter is set, the RCU unsafe checker callback does not run the > > tests to see if RCU is safe or not. > > Please add something saying what we do instead of testing RCU safety. > Looks to me like it skips not only the tests, but also invoking the > callback, but I could easily be wrong. Yeah, the change log sucks. I wrote the change logs after 1am and was half asleep. I see I wrote "Add" as "Adde" ;-) > > > This is required by the graph tracer because the checks can cause > > the graph tracer to live lock the system by its own calls. > > > > It's also needed by the irqsoff tracer, because it may be called > > in RCU unsafe regions and if its internal functions get traced > > then the RCU unsafe checker may have some false positives. > > > > Signed-off-by: Steven Rostedt > > With the augmented commit log as noted above: > > Acked-by: Paul E. McKenney > Thanks, come Tuesday, I'll update the logs. -- Steve > > --- > > kernel/trace/trace.h | 12 +++++++++--- > > kernel/trace/trace_functions.c | 15 +++++++++++++++ > > 2 files changed, 24 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > > index e551316..58e4c37 100644 > > --- a/kernel/trace/trace.h > > +++ b/kernel/trace/trace.h > > @@ -760,9 +760,6 @@ static inline int ftrace_graph_addr(unsigned long addr)