Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758256AbZGGPvt (ORCPT ); Tue, 7 Jul 2009 11:51:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756062AbZGGPvm (ORCPT ); Tue, 7 Jul 2009 11:51:42 -0400 Received: from viefep22-int.chello.at ([62.179.121.42]:31619 "EHLO viefep22-int.chello.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755607AbZGGPvl (ORCPT ); Tue, 7 Jul 2009 11:51:41 -0400 X-SourceIP: 213.93.53.227 Subject: Re: [PATCHv5 2/2] memory barrier: adding smp_mb__after_lock From: Peter Zijlstra To: Oleg Nesterov Cc: Mathieu Desnoyers , Jiri Olsa , Ingo Molnar , Eric Dumazet , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, fbl@redhat.com, nhorman@redhat.com, davem@redhat.com, htejun@gmail.com, jarkao2@gmail.com, davidel@xmailserver.org In-Reply-To: <20090707154440.GA15605@redhat.com> References: <4A4DCD54.1080908@gmail.com> <20090703092438.GE3902@elte.hu> <20090703095659.GA4518@jolsa.lab.eng.brq.redhat.com> <20090703102530.GD32128@elte.hu> <20090703111848.GA10267@jolsa.lab.eng.brq.redhat.com> <20090707101816.GA6619@jolsa.lab.eng.brq.redhat.com> <20090707134601.GB6619@jolsa.lab.eng.brq.redhat.com> <20090707140135.GA5506@Krystal> <20090707143416.GB11704@redhat.com> <20090707150406.GC7124@Krystal> <20090707154440.GA15605@redhat.com> Content-Type: text/plain Date: Tue, 07 Jul 2009 17:50:15 +0200 Message-Id: <1246981815.9777.12.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 841 Lines: 23 On Tue, 2009-07-07 at 17:44 +0200, Oleg Nesterov wrote: > On 07/07, Mathieu Desnoyers wrote: > > > > Actually, thinking about it more, to appropriately support x86, as well > > as powerpc, arm and mips, we would need something like: > > > > read_lock_smp_mb() > > > > Which would be a read_lock with an included memory barrier. > > Then we need read_lock_irq_smp_mb, read_lock_irqsave__smp_mb, write_lock_xxx, > otherwise it is not clear why only read_lock() has _smp_mb() version. > > The same for spin_lock_xxx... At which time the smp_mb__{before,after}_{un,}lock become attractive again. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/