From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933657Ab2JKBjx (ORCPT ); Wed, 10 Oct 2012 21:39:53 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:59285 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933384Ab2JKBNi (ORCPT ); Wed, 10 Oct 2012 21:13:38 -0400 X-Sasl-enc: R9Ycc4nfhAhctXWKbw3p/wy3BDI/VUgOOygq14YWdmMK 1349918017 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, "Paul E. McKenney" , Frederic Weisbecker , Mikael Starvik , Jesper Nilsson , Cris , Josh Triplett Subject: [ 094/120] cris: Add missing RCU idle APIs on idle loop Date: Thu, 11 Oct 2012 10:00:46 +0900 Message-Id: <20121011005844.132602658@linuxfoundation.org> X-Mailer: git-send-email 1.8.0.rc0.18.gf84667d In-Reply-To: <20121011005825.364610894@linuxfoundation.org> References: <20121011005825.364610894@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Frederic Weisbecker commit c633f9e788928e91ad11f44df29b47bbbe9550b0 upstream. In the old times, the whole idle task was considered as an RCU quiescent state. But as RCU became more and more successful overtime, some RCU read side critical section have been added even in the code of some architectures idle tasks, for tracing for example. So nowadays, rcu_idle_enter() and rcu_idle_exit() must be called by the architecture to tell RCU about the part in the idle loop that doesn't make use of rcu read side critical sections, typically the part that puts the CPU in low power mode. This is necessary for RCU to find the quiescent states in idle in order to complete grace periods. Add this missing pair of calls in the Cris's idle loop. Reported-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker Cc: Mikael Starvik Cc: Jesper Nilsson Cc: Cris Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett Signed-off-by: Greg Kroah-Hartman --- arch/cris/kernel/process.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/cris/kernel/process.c +++ b/arch/cris/kernel/process.c @@ -25,6 +25,7 @@ #include #include #include +#include //#define DEBUG @@ -102,6 +103,7 @@ void cpu_idle (void) { /* endless idle loop with no priority at all */ while (1) { + rcu_idle_enter(); while (!need_resched()) { void (*idle)(void); /* @@ -114,6 +116,7 @@ void cpu_idle (void) idle = default_idle; idle(); } + rcu_idle_exit(); schedule_preempt_disabled(); } }