From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933098Ab2JKBND (ORCPT ); Wed, 10 Oct 2012 21:13:03 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:33597 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932876Ab2JKBM5 (ORCPT ); Wed, 10 Oct 2012 21:12:57 -0400 X-Sasl-enc: /1asdZxDm3OE3qkHUhJaXDpYAAQWBqA8Bs9rSPEoWfkd 1349917976 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 , David Howells , Josh Triplett Subject: [ 090/120] frv: Add missing RCU idle APIs on idle loop Date: Thu, 11 Oct 2012 10:00:42 +0900 Message-Id: <20121011005843.294541182@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 41d8fe5bb3cf91ce2716ac8f43e4b40d802a99c8 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 Frv's idle loop. Reported-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker Cc: David Howells Acked-by: David Howells Reviewed-by: Josh Triplett Signed-off-by: Greg Kroah-Hartman --- arch/frv/kernel/process.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/frv/kernel/process.c +++ b/arch/frv/kernel/process.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include @@ -84,12 +85,14 @@ void cpu_idle(void) { /* endless idle loop with no priority at all */ while (1) { + rcu_idle_enter(); while (!need_resched()) { check_pgt_cache(); if (!frv_dma_inprogress && idle) idle(); } + rcu_idle_exit(); schedule_preempt_disabled(); }