From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752203AbbAQEOG (ORCPT ); Fri, 16 Jan 2015 23:14:06 -0500 Received: from www.osadl.org ([62.245.132.105]:55578 "EHLO www.osadl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751618AbbAQEOE (ORCPT ); Fri, 16 Jan 2015 23:14:04 -0500 From: Nicholas Mc Guire To: Ingo Molnar Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, Nicholas Mc Guire Subject: [PATCH] locks should not be needed for reading completion state Date: Sat, 17 Jan 2015 05:05:34 +0100 Message-Id: <1421467534-22834-1-git-send-email-der.herr@hofr.at> X-Mailer: git-send-email 1.7.10.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Nicholas Mc Guire --- Should that not be enough to wrap it into ACCESS_ONCE() here ? Not a wild performance benefit - but might be worth it anyway kernel/sched/completion.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c index 607f852..7c5cd70 100644 --- a/kernel/sched/completion.c +++ b/kernel/sched/completion.c @@ -288,13 +288,6 @@ EXPORT_SYMBOL(try_wait_for_completion); */ bool completion_done(struct completion *x) { - unsigned long flags; - int ret = 1; - - spin_lock_irqsave(&x->wait.lock, flags); - if (!x->done) - ret = 0; - spin_unlock_irqrestore(&x->wait.lock, flags); - return ret; + return !ACCESS_ONCE(x->done); } EXPORT_SYMBOL(completion_done); -- 1.7.10.4