From: Daniel Lezcano <daniel.lezcano@free•fr>
To: Patrick McHardy <kaber@trash•net>
Cc: Eric Dumazet <eric.dumazet@gmail•com>,
Andrian Nord <nightnord@gmail•com>,
lxc-users@lists•sourceforge.net,
Linux Netdev List <netdev@vger•kernel.org>
Subject: Re: [Lxc-users] Bad checksums and lost packets with macvlan on dummy
Date: Tue, 01 Mar 2011 21:04:42 +0100 [thread overview]
Message-ID: <4D6D515A.8060707@free.fr> (raw)
In-Reply-To: <4D6D2402.6020705@trash.net>
On 03/01/2011 05:51 PM, Patrick McHardy wrote:
> On 01.03.2011 14:29, Daniel Lezcano wrote:
>> On 02/28/2011 08:45 AM, Eric Dumazet wrote:
>>>> In the normal case, dummy0 is supposed to drop the packets. But with
>>>> macvlan these packets are broadcasted to the other macvlan ports, so no
>>>> checksum is computed when the packets are transmitted between macvlan1
>>>> and macvlan2.
>>> So where frames get bad checksums ?
>>>
>>> In this "bridge" mode, I suspect the broadcast is done _before_ sending
>>> frame to dummy, so maybe macvlan should not inherit from lowerdev in
>>> this particular case ?
>> Hi Eric,
>>
>> yes, you are right, the packets are sent before.
>>
>> In the 'macvlan_queue_xmit', the code checks the dev is in 'bridge'
>> mode. If so, it looks if there is a destination port for the packet and
>> then calls the 'forward' callback which is 'dev_forward_skb'.
>>
>> I was able to reproduce the same problem with qemu and an emulated
>> 'e1000' card instead of dummy0. The packets are dropped too.
>>
>> 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:
---
drivers/net/macvlan.c | 1 +
1 file changed, 1 insertion(+)
Index: linux-next/drivers/net/macvlan.c
===================================================================
--- 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 ?
Thanks
-- Daniel
next prev parent reply other threads:[~2011-03-01 20:04 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20110221150710.GA5651@nord.niifaq.ru>
[not found] ` <4D6282DB.2080204@free.fr>
[not found] ` <20110221153421.GA6602@nord.niifaq.ru>
2011-02-21 16:07 ` [Lxc-users] Huge ammount of invalid checksum packets on macvlan Daniel Lezcano
[not found] ` <4D628DC3.9000400-GANU6spQydw@public.gmane.org>
2011-02-21 17:39 ` Andrian Nord
2011-02-23 17:13 ` [Lxc-users] Bad checksums and lost packets with macvlan on dummy Andrian Nord
2011-02-24 10:20 ` Daniel Lezcano
2011-02-26 20:38 ` Andrian Nord
2011-02-27 15:14 ` Daniel Lezcano
2011-02-27 19:50 ` Eric Dumazet
2011-02-27 20:35 ` Daniel Lezcano
2011-02-28 7:45 ` [Lxc-users] " Eric Dumazet
2011-03-01 13:29 ` Daniel Lezcano
2011-03-01 16:51 ` Patrick McHardy
2011-03-01 20:04 ` Daniel Lezcano [this message]
2011-03-02 11:03 ` Patrick McHardy
2011-03-02 16:03 ` Daniel Lezcano
2011-03-02 18:03 ` Patrick McHardy
2011-03-02 18:33 ` Daniel Lezcano
2011-03-03 14:30 ` Changli Gao
2011-03-08 14:41 ` Patrick McHardy
[not found] ` <4D764030.8020202-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org>
2011-03-12 21:59 ` Daniel Lezcano
2011-03-12 22:07 ` [Lxc-users] " Daniel Lezcano
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