Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933058Ab2HVQYb (ORCPT ); Wed, 22 Aug 2012 12:24:31 -0400 Received: from mail-ey0-f174.google.com ([209.85.215.174]:33198 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964781Ab2HVQYZ (ORCPT ); Wed, 22 Aug 2012 12:24:25 -0400 From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Chris Zankel , "3.2.x.." , "Paul E. McKenney" Subject: [PATCH 10/10] xtensa: Add missing RCU idle APIs on idle loop Date: Wed, 22 Aug 2012 18:23:48 +0200 Message-Id: <1345652628-15060-11-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1345652628-15060-1-git-send-email-fweisbec@gmail.com> References: <1345652628-15060-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1836 Lines: 57 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 xtensa's idle loop. Reported-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker Cc: Chris Zankel Cc: 3.2.x.. Cc: Paul E. McKenney --- arch/xtensa/kernel/process.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c index 2c8d6a3..bc44311 100644 --- a/arch/xtensa/kernel/process.c +++ b/arch/xtensa/kernel/process.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include @@ -110,8 +111,10 @@ void cpu_idle(void) /* endless idle loop with no priority at all */ while (1) { + rcu_idle_enter(); while (!need_resched()) platform_idle(); + rcu_idle_exit(); schedule_preempt_disabled(); } } -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/