From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor ownership. Date: Wed, 02 May 2007 16:30:19 -0500 Message-ID: <463902EB.8070401@freescale.com> References: <20070502195712.GA16541@ld0162-tx32.am.freescale.net> <4638F0C4.2000406@freescale.com> <4638F734.2040809@freescale.com> <41B347BE-06AA-4346-BEFB-19DFB52AC533@kernel.crashing.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: jgarzik@pobox.com, netdev@vger.kernel.org, linuxppc-dev@ozlabs.org To: Kumar Gala Return-path: Received: from de01egw02.freescale.net ([192.88.165.103]:50935 "EHLO de01egw02.freescale.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1767030AbXEBVag (ORCPT ); Wed, 2 May 2007 17:30:36 -0400 In-Reply-To: <41B347BE-06AA-4346-BEFB-19DFB52AC533@kernel.crashing.org> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Kumar Gala wrote: > Why doesn't marking the bdp pointer volatile resolve the issue in > gfar_clean_rx_ring() to ensure load ordering? Because that only addresses compiler reordering (and does so in a rather clumsy way -- not all accesses need to be strongly ordered), not hardware reordering. -Scott