From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754315Ab1LCSe4 (ORCPT ); Sat, 3 Dec 2011 13:34:56 -0500 Received: from e3.ny.us.ibm.com ([32.97.182.143]:38327 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753689Ab1LCSex (ORCPT ); Sat, 3 Dec 2011 13:34:53 -0500 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, patches@linaro.org, Frederic Weisbecker , "Paul E. McKenney" Subject: [PATCH RFC tip/core/rcu 1/7] rcu: Don't check irq nesting from rcu idle entry/exit Date: Sat, 3 Dec 2011 10:34:36 -0800 Message-Id: <1322937282-19846-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <20111203183417.GA18914@linux.vnet.ibm.com> References: <20111203183417.GA18914@linux.vnet.ibm.com> x-cbid: 11120318-8974-0000-0000-000003E43D3E Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Frederic Weisbecker Because tasks do not nest, rcu_idle_enter() and rcu_idle_exit() do not need to check for nesting. This commit therefore moves nesting checks from rcu_idle_enter_common() to rcu_irq_exit() and from rcu_idle_exit_common() to rcu_irq_enter(). Signed-off-by: Frederic Weisbecker Cc: Josh Triplett Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 18 ++++++++---------- 1 files changed, 8 insertions(+), 10 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index bf085d7..860c02c 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -350,10 +350,6 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp) */ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval) { - if (rdtp->dynticks_nesting) { - trace_rcu_dyntick("--=", oldval, rdtp->dynticks_nesting); - return; - } trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting); if (!is_idle_task(current)) { struct task_struct *idle = idle_task(smp_processor_id()); @@ -426,7 +422,10 @@ void rcu_irq_exit(void) oldval = rdtp->dynticks_nesting; rdtp->dynticks_nesting--; WARN_ON_ONCE(rdtp->dynticks_nesting < 0); - rcu_idle_enter_common(rdtp, oldval); + if (rdtp->dynticks_nesting) + trace_rcu_dyntick("--=", oldval, rdtp->dynticks_nesting); + else + rcu_idle_enter_common(rdtp, oldval); local_irq_restore(flags); } @@ -439,10 +438,6 @@ void rcu_irq_exit(void) */ static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval) { - if (oldval) { - trace_rcu_dyntick("++=", oldval, rdtp->dynticks_nesting); - return; - } smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ atomic_inc(&rdtp->dynticks); /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ @@ -518,7 +513,10 @@ void rcu_irq_enter(void) oldval = rdtp->dynticks_nesting; rdtp->dynticks_nesting++; WARN_ON_ONCE(rdtp->dynticks_nesting == 0); - rcu_idle_exit_common(rdtp, oldval); + if (oldval) + trace_rcu_dyntick("++=", oldval, rdtp->dynticks_nesting); + else + rcu_idle_exit_common(rdtp, oldval); local_irq_restore(flags); } -- 1.7.3.2