From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754187AbZHYCZf (ORCPT ); Mon, 24 Aug 2009 22:25:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754100AbZHYCZe (ORCPT ); Mon, 24 Aug 2009 22:25:34 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:54170 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754018AbZHYCZe (ORCPT ); Mon, 24 Aug 2009 22:25:34 -0400 Date: Mon, 24 Aug 2009 19:25:32 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josht@linux.vnet.ibm.com, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org Subject: Re: [PATCH -tip 1/2] Add "notrace" to RCU function headers used by ftrace. Message-ID: <20090825022532.GD7355@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20090824164112.GA13693@linux.vnet.ibm.com> <20090825020221.GA7355@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 24, 2009 at 10:11:40PM -0400, Steven Rostedt wrote: > > On Mon, 24 Aug 2009, Paul E. McKenney wrote: > > > On Mon, Aug 24, 2009 at 07:38:51PM -0400, Steven Rostedt wrote: > > > > > > On Mon, 24 Aug 2009, Paul E. McKenney wrote: > > > > > > > Both rcu_read_lock_sched_notrace() and rcu_read_unlock_sched_notrace() > > > > are used by ftrace, and thus need to be marked "notrace". Unfortunately, > > > > my naive assumption that gcc would see the inner "notrace" does not hold. > > > > Kudos to Lai Jiangshan for noting this. > > > > > > > > Signed-off-by: Paul E. McKenney > > > > --- > > > > include/linux/rcupdate.h | 4 ++-- > > > > 1 files changed, 2 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > > > > index ec90fc3..8b4422c 100644 > > > > --- a/include/linux/rcupdate.h > > > > +++ b/include/linux/rcupdate.h > > > > @@ -191,7 +191,7 @@ static inline void rcu_read_lock_sched(void) > > > > __acquire(RCU_SCHED); > > > > rcu_read_acquire(); > > > > } > > > > -static inline void rcu_read_lock_sched_notrace(void) > > > > +static inline notrace void rcu_read_lock_sched_notrace(void) > > > > { > > > > preempt_disable_notrace(); > > > > __acquire(RCU_SCHED); > > > > @@ -209,7 +209,7 @@ static inline void rcu_read_unlock_sched(void) > > > > __release(RCU_SCHED); > > > > preempt_enable(); > > > > } > > > > -static inline void rcu_read_unlock_sched_notrace(void) > > > > +static inline notrace void rcu_read_unlock_sched_notrace(void) > > > > > > Funny, inlines should not be traced. Is gcc ignoring the inlines here? > > > > Well, that was my line of thinking as well, until Lai Jiangshan set > > me straight. Version 4.x of gcc apparently decides on a case-by-case > > basis. > > Yeah, I've seen gcc do it, but when it does it to static inlines in header > files, I just get a feeling to squinge. Especially when they are as short and simple as those particular functions were... Thanx, Paul