From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758652Ab3IYBm6 (ORCPT ); Tue, 24 Sep 2013 21:42:58 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:36925 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757730Ab3IYBmz (ORCPT ); Tue, 24 Sep 2013 21:42:55 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 03/10] rcu: Flag lockless access to ->gp_flags with ACCESS_ONCE() Date: Tue, 24 Sep 2013 18:42:32 -0700 Message-Id: <1380073359-31959-3-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1380073359-31959-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20130925014210.GA31690@linux.vnet.ibm.com> <1380073359-31959-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13092501-0928-0000-0000-000001DB9FF1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" This commit applies ACCESS_ONCE() to an outside-of-lock access to ->gp_flags. Although it is hard to imagine any sane compiler messing this particular case up, the documentation benefits are substantial. Plus the definition of "sane compiler" grows ever looser. Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 62b67b7..6d028fd 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1481,7 +1481,7 @@ static int __noreturn rcu_gp_kthread(void *arg) /* Handle grace-period start. */ for (;;) { wait_event_interruptible(rsp->gp_wq, - rsp->gp_flags & + ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_INIT); if (rcu_gp_init(rsp)) break; -- 1.8.1.5