From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kieran Mansley Subject: Re: [PATCH 0/2] Disable forwarding of LRO skbs Date: Thu, 01 May 2008 12:18:08 +0100 Message-ID: <1209640688.4191.35.camel@moonstone.uk.level5networks.com> References: <20080430214845.GC14219@solarflare.com> <20080501110225.GG14219@solarflare.com> <1209640128.4191.30.camel@moonstone.uk.level5networks.com> <20080501111247.GA7756@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Ben Hutchings , davem@davemloft.net, shemminger@vyatta.com, netdev@vger.kernel.org To: Herbert Xu Return-path: Received: from 216-237-3-220.orange.nextweb.net ([216.237.3.220]:2721 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753407AbYEALSN (ORCPT ); Thu, 1 May 2008 07:18:13 -0400 In-Reply-To: <20080501111247.GA7756@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2008-05-01 at 19:12 +0800, Herbert Xu wrote: > On Thu, May 01, 2008 at 12:08:48PM +0100, Kieran Mansley wrote: > > > > Yes, everything works fine in that case. It's only when LRO packets are > > forwarded to another physical interface that things go wrong. > > Now this is definitely broken because it fiddles with TCP packets > in the middle, but still it should *work* in as much as making the > packet go out. Well except that you need to fix up the checksum > so that it only contains the pseudo-header on output. That's > probably what you need to address if we failed in avoiding LRO > on forwarded traffic. If I remember rightly it also gets upset when it comes to split the packet because the frag_list is already in use; it expects this not to be the case for GSO but it's valid for an LRO packet to do this I think. I don't think there's anything fundamentally difficult here, it's just that the code has never been written to cope. Kieran