From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755457Ab0AMKZ4 (ORCPT ); Wed, 13 Jan 2010 05:25:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755335Ab0AMKZa (ORCPT ); Wed, 13 Jan 2010 05:25:30 -0500 Received: from hera.kernel.org ([140.211.167.34]:37984 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932070Ab0AMKZ3 (ORCPT ); Wed, 13 Jan 2010 05:25:29 -0500 Date: Wed, 13 Jan 2010 10:25:01 GMT From: "tip-bot for Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <12626465501994-git-send-email-> References: <12626465501994-git-send-email-> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/rcu] rcu: Adjust force_quiescent_state() locking, step 2 Message-ID: Git-Commit-ID: 559569acf94f538b56bd6eead80b439d6a78cdff X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Wed, 13 Jan 2010 10:25:02 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 559569acf94f538b56bd6eead80b439d6a78cdff Gitweb: http://git.kernel.org/tip/559569acf94f538b56bd6eead80b439d6a78cdff Author: Paul E. McKenney AuthorDate: Mon, 4 Jan 2010 15:09:01 -0800 Committer: Ingo Molnar CommitDate: Wed, 13 Jan 2010 09:06:01 +0100 rcu: Adjust force_quiescent_state() locking, step 2 This patch releases rnp->lock after the end of force_quiescent_state()'s switch statement. This is a second step towards prohibiting starting grace periods while force_quiescent_state() is executing, which will reduce the number and complexity of races that force_quiescent_state() is involved in. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <12626465501994-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcutree.c | 13 +++---------- 1 files changed, 3 insertions(+), 10 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index eae331d..d42ad30 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1219,7 +1219,6 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) case RCU_GP_IDLE: case RCU_GP_INIT: - spin_unlock(&rnp->lock); break; /* grace period idle or initializing, ignore. */ case RCU_SAVE_DYNTICK: @@ -1246,10 +1245,8 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) rsp->completed_fqs = lastcomp; forcenow = signaled == RCU_SAVE_COMPLETED; } - if (!forcenow) { - spin_unlock(&rnp->lock); + if (!forcenow) break; - } /* fall into next case. */ case RCU_FORCE_QS: @@ -1262,14 +1259,10 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) /* Leave state in case more forcing is required. */ - break; - - default: - - spin_unlock(&rnp->lock); - WARN_ON_ONCE(1); + spin_lock(&rnp->lock); break; } + spin_unlock(&rnp->lock); unlock_fqs_ret: spin_unlock_irqrestore(&rsp->fqslock, flags); }