From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753587Ab1K2BAy (ORCPT ); Mon, 28 Nov 2011 20:00:54 -0500 Received: from mail-ey0-f174.google.com ([209.85.215.174]:49154 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752874Ab1K2BAw (ORCPT ); Mon, 28 Nov 2011 20:00:52 -0500 Date: Tue, 29 Nov 2011 02:00:48 +0100 From: Frederic Weisbecker To: "Paul E. McKenney" Cc: LKML , Josh Triplett Subject: Re: [PATCH 2/4] rcu: Irq nesting is always 0 on rcu_enter_idle_common Message-ID: <20111129010045.GC18182@somewhere.redhat.com> References: <1322515487-18690-1-git-send-email-fweisbec@gmail.com> <1322515487-18690-3-git-send-email-fweisbec@gmail.com> <20111129002914.GP2346@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111129002914.GP2346@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 28, 2011 at 04:29:14PM -0800, Paul E. McKenney wrote: > On Mon, Nov 28, 2011 at 10:24:45PM +0100, Frederic Weisbecker wrote: > > So pass 0 directly as a nesting value on the tracing calls. > > > > Signed-off-by: Frederic Weisbecker > > Cc: Josh Triplett > > --- > > kernel/rcutree.c | 5 ++--- > > 1 files changed, 2 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > > index c2aaadf..b80cb41 100644 > > --- a/kernel/rcutree.c > > +++ b/kernel/rcutree.c > > @@ -350,11 +350,10 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp) > > */ > > static void rcu_idle_enter_common(struct rcu_dynticks *rdtp) > > { > > - trace_rcu_dyntick("Start", rdtp->dynticks_nesting); > > + trace_rcu_dyntick("Start", 0); > > if (!idle_cpu(smp_processor_id())) { > > WARN_ON_ONCE(1); /* must be idle task! */ > > - trace_rcu_dyntick("Error on entry: not idle task", > > - rdtp->dynticks_nesting); > > + trace_rcu_dyntick("Error on entry: not idle task", 0); > > ftrace_dump(DUMP_ALL); > > } > > /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ > > Queued, again updating to work around the mid-air collision. > > Thanx, Paul > > ------------------------------------------------------------------------ > > rcu: Irq nesting is always 0 on rcu_enter_idle_common > > Because tasks don't nest, the ->dyntick_nesting must always be zero upon > entry to rcu_idle_enter_common(). Therefore, pass "0" rather than the > counter itself. And with a better changelog. Thanks! > > Signed-off-by: Frederic Weisbecker > Cc: Josh Triplett > Signed-off-by: Paul E. McKenney > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > index 54d9b4f..e0f5072 100644 > --- a/kernel/rcutree.c > +++ b/kernel/rcutree.c > @@ -350,12 +350,11 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp) > */ > static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval) > { > - trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting); > + trace_rcu_dyntick("Start", oldval, 0); > if (!is_idle_task(current)) { > struct task_struct *idle = idle_task(smp_processor_id()); > > - trace_rcu_dyntick("Error on entry: not idle task", > - oldval, rdtp->dynticks_nesting); > + trace_rcu_dyntick("Error on entry: not idle task", oldval, 0); > ftrace_dump(DUMP_ALL); > WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", > current->pid, current->comm, >