From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net] amd-xgbe: Fix race between access of desc and desc index Date: Sun, 01 Nov 2015 12:04:04 -0500 (EST) Message-ID: <20151101.120404.1795383010650058295.davem@davemloft.net> References: <20151026221354.927.9237.stgit@tlendack-t1.amdoffice.net> <20151027.195007.1435133435434786670.davem@davemloft.net> <5630D234.3070600@amd.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, alexander.duyck@gmail.com To: thomas.lendacky@amd.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:53891 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751123AbbKAREF (ORCPT ); Sun, 1 Nov 2015 12:04:05 -0500 In-Reply-To: <5630D234.3070600@amd.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Tom Lendacky Date: Wed, 28 Oct 2015 08:48:36 -0500 > On 10/27/2015 09:50 PM, David Miller wrote: >> From: Tom Lendacky >> Date: Mon, 26 Oct 2015 17:13:54 -0500 >> >>> During Tx cleanup it's still possible for the descriptor data to be >>> read ahead of the descriptor index. A memory barrier is required >>> between >>> the read of the descriptor index and the start of the Tx cleanup loop. >>> This allows a change to a lighter-weight barrier in the Tx transmit >>> routine just before updating the current descriptor index. >>> >>> Since the memory barrier does result in extra overhead on arm64, keep >>> the previous change to not chase the current descriptor value. This >>> prevents the execution of the barrier for each loop performed. >>> >>> Suggested-by: Alexander Duyck >>> Signed-off-by: Tom Lendacky >> >> Applied, thanks. >> > > Thanks David. Could you queue this up for the 4.1 and 4.2 stable > trees? Ok, done.