From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [Lxc-users] Bad checksums and lost packets with macvlan on dummy Date: Wed, 02 Mar 2011 17:03:33 +0100 Message-ID: <4D6E6A55.6000607@free.fr> References: <20110221150710.GA5651@nord.niifaq.ru> <4D6282DB.2080204@free.fr> <20110221153421.GA6602@nord.niifaq.ru> <4D628DC3.9000400@free.fr> <20110223170512.GA10277@nord.niifaq.ru> <4D6A6A5F.4030707@free.fr> <1298836236.8726.109.camel@edumazet-laptop> <4D6AB578.3010704@free.fr> <1298879114.8726.131.camel@edumazet-laptop> <4D6CF4A8.6000205@free.fr> <4D6D2402.6020705@trash.net> <4D6D515A.8060707@free.fr> <4D6E23F3.4010402@trash.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: Eric Dumazet , Andrian Nord , lxc-users@lists.sourceforge.net, Linux Netdev List To: Patrick McHardy Return-path: Received: from smtp5-g21.free.fr ([212.27.42.5]:59024 "EHLO smtp5-g21.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751384Ab1CBQDn (ORCPT ); Wed, 2 Mar 2011 11:03:43 -0500 In-Reply-To: <4D6E23F3.4010402@trash.net> Sender: netdev-owner@vger.kernel.org List-ID: On 03/02/2011 12:03 PM, Patrick McHardy wrote: > Am 01.03.2011 21:04, schrieb Daniel Lezcano: >> On 03/01/2011 05:51 PM, Patrick McHardy wrote: >>>> Patrick, do you have any suggestions to fix this ? >>> Since the frames are only looped back locally, I suppose the easiest >>> fix would be to mark them with CHECKSUM_UNNECESSARY. Alternatively >>> we need to complete the checksum manually, similar to what >>> dev_hard_start_xmit() does. >> That sounds very simple to fix, maybe too much simple :) >> >> I did the following change: >> >> --- linux-next.orig/drivers/net/macvlan.c >> +++ linux-next/drivers/net/macvlan.c >> @@ -222,6 +222,7 @@ static int macvlan_queue_xmit(struct sk_ >> >> if (vlan->mode == MACVLAN_MODE_BRIDGE) { >> const struct ethhdr *eth = (void *)skb->data; >> + skb->ip_summed = CHECKSUM_UNNECESSARY; >> >> /* send to other bridge ports directly */ >> if (is_multicast_ether_addr(eth->h_dest)) { >> >> >> and that fixed the problem. Do you think it is acceptable ? > The only problem I see is if the packets are bridged to a > different networking device (or redirected using the mirred > action), in this case the checksum will not be completed. > This would be a very strange setup though and probably wouldn't > be using dummy as lower device, so I'm not sure we have to > worry about this case. I am not sure to get it, do you say the patch is correct ? If my understanding is correct, the packet will be flagged CHECKSUM_UNNECESSARY only for the macvlan devices, right ? By the way, this problem occurs for any lower device with offloading capabilities with a macvlan port in bridge mode. Thanks -- Daniel