From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754995AbbAFLs7 (ORCPT ); Tue, 6 Jan 2015 06:48:59 -0500 Received: from casper.infradead.org ([85.118.1.10]:53685 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751540AbbAFLs6 (ORCPT ); Tue, 6 Jan 2015 06:48:58 -0500 Date: Tue, 6 Jan 2015 12:48:42 +0100 From: Peter Zijlstra To: Kent Overstreet Cc: Sedat Dilek , Dave Jones , Linus Torvalds , LKML , Chris Mason Subject: Re: Linux 3.19-rc3 Message-ID: <20150106114842.GP10476@twins.programming.kicks-ass.net> References: <20150106094039.GI29390@twins.programming.kicks-ass.net> <20150106100621.GL29390@twins.programming.kicks-ass.net> <20150106110112.GQ29390@twins.programming.kicks-ass.net> <20150106110730.GA25846@kmo-pixel> <20150106114215.GS29390@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150106114215.GS29390@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Looking at that closure stuff, why is there an smp_mb() in closure_wake_up() ? Typically wakeup only needs to imply a wmb. Also note that __closure_wake_up() starts with a fully serializing instruction (xchg) and thereby already implies the full barrier.