From mboxrd@z Thu Jan 1 00:00:00 1970 From: Edward Cree Subject: Re: [RFC PATCH 3/4] net: Store checksum result for offloaded GSO checksums Date: Thu, 14 Jan 2016 12:02:33 +0000 Message-ID: <56978E59.4070406@solarflare.com> References: <20160114045532.5119.56124.stgit@localhost.localdomain> <20160114051214.5119.63241.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit To: Alexander Duyck , , Return-path: Received: from nbfkord-smmo04.seg.att.com ([209.65.160.86]:30511 "EHLO nbfkord-smmo04.seg.att.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752841AbcANMCl (ORCPT ); Thu, 14 Jan 2016 07:02:41 -0500 In-Reply-To: <20160114051214.5119.63241.stgit@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: On 14/01/16 05:12, Alexander Duyck wrote: > In order to do that I replaced CHECKSUM_PARTIAL with > CHECKSUM_UNNECESSARY in the case of us computing checksums for the outer > header while skipping computing checksums for the inner headers. We clean > up the ip_summed flag and set it to either CHECKSUM_PARTIAL or > CHECKSUM_NONE once we hand the packet off to the next lower level. I feel like this should probably be mentioned in the comment at thetop of skbuff.h. I think section E of that comment will need to be more or less completely re-written with this patch series. In particular, if I'm understandingcorrectly, csum_start and csum_offset will point to the inner checksum (unless using RCO), same as they do without GSO. And GSO will never offload multiple checksums (although TSO will still have to _edit_ multiple checksums). Or better still, proper documentation of GSO and TSO would be nice :)