From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH v6 2/2] net: ip, ipv6: handle gso skbs in forwarding path Date: Thu, 13 Feb 2014 17:17:57 -0500 (EST) Message-ID: <20140213.171757.1460052863443832827.davem@davemloft.net> References: <1392329352-31606-1-git-send-email-fw@strlen.de> <1392329352-31606-2-git-send-email-fw@strlen.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: fw@strlen.de Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:50670 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751464AbaBMWR6 (ORCPT ); Thu, 13 Feb 2014 17:17:58 -0500 In-Reply-To: <1392329352-31606-2-git-send-email-fw@strlen.de> Sender: netdev-owner@vger.kernel.org List-ID: From: Florian Westphal Date: Thu, 13 Feb 2014 23:09:12 +0100 > Marcelo Ricardo Leitner reported problems when the forwarding link path > has a lower mtu than the incoming one if the inbound interface supports GRO. ... > However it turns out that skb_segment() assumes skb nr_frags is related > to mss size so we would BUG there. I don't want to mess with it considering > Herbert and Eric disagree on what the correct behavior should be. > > Hannes Frederic Sowa notes that when we would shrink gso_size > skb_segment would then also need to deal with the case where > SKB_MAX_FRAGS would be exceeded. > > This uses sofware segmentation in the forward path when we hit ipv4 > non-DF packets and the outgoing link mtu is too small. Its not perfect, > but given the lack of bug reports wrt. GRO fwd being broken this is a > rare case anyway. Also its not like this could not be improved later > once the dust settles. > > Acked-by: Herbert Xu > Reported-by: Marcelo Ricardo Leitner > Signed-off-by: Florian Westphal Also applied and queued up for -stable, thanks.