On Tue, Aug 30, 2011 at 04:42:42PM +0200, Eric Dumazet wrote:

Le mardi 30 août 2011 à 16:23 +0200, Ruslan N. Marchenko a écrit :

quoted

On Tue, Aug 30, 2011 at 03:46:24PM +0200, Ruslan N. Marchenko wrote:

quoted

On Tue, Aug 30, 2011 at 03:23:48PM +0200, Eric Dumazet wrote:

quoted

What kernel version are you using ?

Oh, sorry for missing it, it runs on 
Linux ruff.mobi 2.6.38-11-generic #48-Ubuntu SMP Fri Jul 29 19:05:14 UTC 2011 i686 i686 i386 GNU/Linux

Just fyi - the openwrt box to which it is connected is 
Linux OpenWrt 2.6.39.2 #2 Fri Aug 12 09:36:23 EEST 2011 mips GNU/Linux
although packet drop happens even if there're no vlans configured on remote side.

Here is double-tag sample:
16:20:31.151268 e0:46:9a:4e:88:1d > 00:26:18:40:21:62, ethertype 802.1Q (0x8100), length 106: vlan 2112, p 7, ethertype 802.1Q, vlan 6, p 0, ethertype IPv4, [|ip]
        0x0000:  0026 1840 2162 e046 9a4e 881d 8100 e840
        0x0010:  8100 0006 0800 4500 0054 abec 0000

Latest kernel should be fine. Some patches need to be backported by
Ubuntu team, if you can test them.

commit 9331db4f00cfee8a79d2147ac83723ef436b9759
Author: Jiri Pirko [off-list ref]
Date:   Wed Aug 17 23:50:37 2011 -0700

    forcedeth: call vlan_mode only if hw supports vlans
    
    If hw does not support vlans, dont call nv_vlan_mode because it has no point.
    I believe that this should fix issues on older non-vlan supportive
    chips (like Ingo has).
    
    Reported-ty: Ingo Molnar [off-list ref]
    Signed-off-by: Jiri Pirko [off-list ref]
    Signed-off-by: David S. Miller [off-list ref]

commit 0891b0e08937aaec2c4734acb94c5ff8042313bb
Author: Jiri Pirko [off-list ref]
Date:   Tue Jul 26 10:19:28 2011 +0000

    forcedeth: fix vlans
    
    For some reason, when rxaccel is disabled, NV_RX3_VLAN_TAG_PRESENT is
    still set and some pseudorandom vids appear. So check for
    NETIF_F_HW_VLAN_RX as well. Also set correctly hw_features and set vlan
    mode on probe.
    
    Signed-off-by: Jiri Pirko [off-list ref]
    Signed-off-by: David S. Miller [off-list ref]

commit 3326c784c9f492e988617d93f647ae0cfd4c8d09
Author: Jiri Pirko [off-list ref]
Date:   Wed Jul 20 04:54:38 2011 +0000

    forcedeth: do vlan cleanup
    
    - unify vlan and nonvlan rx path
    - kill np->vlangrp and nv_vlan_rx_register
    - allow to turn on/off rx vlan accel via ethtool (set_features)
    
    Signed-off-by: Jiri Pirko [off-list ref]
    Signed-off-by: David S. Miller [off-list ref]

Thanks Eric for quick hint, atom n270 however is not as fast in compiling kernel :D
I'm trying to backport the patch (and dependencies) and compile kernel with it, takes lot of time though. Will report back and raise a report/request to ubuntu kernel team. Anyway it seems exactly what I have.

Cheers,
Ruslan