From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net] amd-xgbe: Fix jumbo MTU processing on newer hardware Date: Wed, 15 Mar 2017 16:43:42 -0700 (PDT) Message-ID: <20170315.164342.1399522126912671968.davem@davemloft.net> References: <20170315.154149.1161814285370679300.davem@davemloft.net> <1b4a099a-66a8-3fdb-01ed-bc110756244a@amd.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: thomas.lendacky@amd.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:56418 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750926AbdCOXts (ORCPT ); Wed, 15 Mar 2017 19:49:48 -0400 In-Reply-To: <1b4a099a-66a8-3fdb-01ed-bc110756244a@amd.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Tom Lendacky Date: Wed, 15 Mar 2017 17:52:44 -0500 > On 3/15/2017 5:41 PM, David Miller wrote: >> From: Tom Lendacky >> Date: Wed, 15 Mar 2017 17:40:51 -0500 >> >>> On 3/15/2017 5:37 PM, David Miller wrote: >>>> From: Tom Lendacky >>>> Date: Wed, 15 Mar 2017 15:11:23 -0500 >>>> >>>>> Newer hardware does not provide a cumulative payload length when >>>>> multiple >>>>> descriptors are needed to handle the data. Once the MTU increases >>>>> beyond >>>>> the size that can be handled by a single descriptor, the SKB does not >>>>> get >>>>> built properly by the driver. >>>>> >>>>> The driver will now calculate the size of the data buffers used by the >>>>> hardware. The first buffer of the first descriptor is for packet >>>>> headers >>>>> or packet headers and data when the headers can't be split. Subsequent >>>>> descriptors in a multi-descriptor chain will not use the first >>>>> buffer. The >>>>> second buffer is used by all the descriptors in the chain for payload >>>>> data. >>>>> Based on whether the driver is processing the first, intermediate, or >>>>> last >>>>> descriptor it can calculate the buffer usage and build the SKB >>>>> properly. >>>>> >>>>> Tested and verified on both old and new hardware. >>>>> >>>>> Signed-off-by: Tom Lendacky >>>> >>>> Applied, thanks Tom. >>> >>> Thanks David. This is another patch for 4.10 stable. Can you please >>> queue it up? >> >> Can you properly state this in your patch postings, instead of always >> mentioning it later? >> > > Sorry, yes, I can do that. I didn't realize you preferred it that > way. > Do you want the "Cc" tag to stable included in the patch or just > mention the stable targets in the patch description? I know you > coordinate the stable submissions and I don't want to mess anything > up. Just put a note after a "---" delimiter, requesting that I queue it up for -stable. Thanks.