From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757489AbaGWFLE (ORCPT ); Wed, 23 Jul 2014 01:11:04 -0400 Received: from mail-yk0-f171.google.com ([209.85.160.171]:49284 "EHLO mail-yk0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757458AbaGWFLA (ORCPT ); Wed, 23 Jul 2014 01:11:00 -0400 From: Pranith Kumar To: "Paul E. McKenney" , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , linux-kernel@vger.kernel.org (open list:READ-COPY UPDATE...) Subject: [PATCH 10/16] rcu: Check for RCU_FLAG_GP_INIT bit in gp_flags for spurious wakeup Date: Wed, 23 Jul 2014 01:09:47 -0400 Message-Id: <1406092194-13004-11-git-send-email-bobby.prani@gmail.com> X-Mailer: git-send-email 2.0.0.rc2 In-Reply-To: <1406092194-13004-1-git-send-email-bobby.prani@gmail.com> References: <1406092194-13004-1-git-send-email-bobby.prani@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org rcu_gp_init() is called once the gp_kthread wakes up on the condition that the init bit is set in the gp_flags. For a spurious wakeup we need to check that it is actually set. This commit ensures that the RCU_GP_FLAG_INIT bit is set in gp_flags. Signed-off-by: Pranith Kumar --- kernel/rcu/tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 8d598a2..f8847d9 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1600,7 +1600,7 @@ static int rcu_gp_init(struct rcu_state *rsp) rcu_bind_gp_kthread(); raw_spin_lock_irq(&rnp->lock); smp_mb__after_unlock_lock(); - if (!ACCESS_ONCE(rsp->gp_flags)) { + if (!(ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_INIT)) { /* Spurious wakeup, tell caller to go back to sleep. */ raw_spin_unlock_irq(&rnp->lock); return 0; -- 2.0.0.rc2