From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933587AbXCPL6d (ORCPT ); Fri, 16 Mar 2007 07:58:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933584AbXCPL6c (ORCPT ); Fri, 16 Mar 2007 07:58:32 -0400 Received: from 207.47.60.4.static.nextweb.net ([207.47.60.4]:7068 "EHLO rpc.xensource.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933587AbXCPL6c (ORCPT ); Fri, 16 Mar 2007 07:58:32 -0400 User-Agent: Microsoft-Entourage/11.2.5.060620 Date: Fri, 16 Mar 2007 11:58:19 +0000 Subject: Re: [Xen-devel] Re: [patch 21/26] Xen-paravirt_ops: Use the hvc console infrastructure for Xen console From: Keir Fraser To: Andrew Morton , Keir Fraser CC: Wright , , , Andi Kleen , , Ingo Molnar , , Keir Fraser Message-ID: Thread-Topic: [Xen-devel] Re: [patch 21/26] Xen-paravirt_ops: Use the hvc console infrastructure for Xen console Thread-Index: AcdnwmNCoft8fNO1EduhtwAX8io7RQ== In-Reply-To: <20070316034123.9de92632.akpm@linux-foundation.org> Mime-version: 1.0 Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 16/3/07 11:41, "Andrew Morton" wrote: >> It's needed for writing data /after/ reading the consumer index that shows >> you have space to write. Looking through xenbus_comms.c I think all the >> barriers are correct except there is a spurious extra mb() in xb_read(), >> where there is a later rmb() which is sufficient by itself. All the others >> have a purpose. >> > > If Ingo couldn't work this out from reading the code then nobody else can, > and we have a maintainability problem which can only be solved with > adequate commenting. Agreed. I've fixed up the commenting, removed the spurious mb(), and I just need Jeremy to merge that change into the Xen pv_ops patchset. :-) -- Keir