From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934199AbZLOXNX (ORCPT ); Tue, 15 Dec 2009 18:13:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934241AbZLOXNK (ORCPT ); Tue, 15 Dec 2009 18:13:10 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.146]:33551 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934184AbZLOXCs (ORCPT ); Tue, 15 Dec 2009 18:02:48 -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, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, "Paul E. McKenney" Subject: [PATCH RFC tip/core/rcu 02/18] rcu: adjust force_quiescent_state() locking, step 2 Date: Tue, 15 Dec 2009 15:02:25 -0800 Message-Id: <12609181611638-git-send-email-> X-Mailer: git-send-email 1.5.2.5 In-Reply-To: <20091215230213.GA9093@linux.vnet.ibm.com> References: <20091215230213.GA9093@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paul E. McKenney Proposed for 2.6.34, not for inclusion. 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 --- 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); } -- 1.5.2.5