netdev - Re: 802.1Q VLAN random tag injected when vlan configured on forcedeth interface

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Date:	Tue, 30 Aug 2011 15:23:48 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	"Ruslan N. Marchenko" <me@...f.mobi>
Cc:	netdev@...r.kernel.org
Subject: Re: 802.1Q VLAN random tag injected when vlan configured on
 forcedeth interface

Le mardi 30 août 2011 à 14:51 +0200, Ruslan N. Marchenko a écrit :
> Hi guys,
> I've faced with strange behaviour of 8021q driver: when enabling vlan subinterface on eth interface I'm getting ~50% packetloss due to packets are marked with incorrect tags (and eventually dropped by kernel since no vlans configured for such IDs).
> Scenario:
> [    0.476950] cpufreq-nforce2: No nForce2 chipset.
> [    1.519133] forcedeth: Reverse Engineered nForce ethernet driver. Version 0.64.
> [    1.519991] forcedeth 0000:00:0a.0: PCI INT A -> Link[LMAC] -> GSI 22 (level, low) -> IRQ 22
> [    1.520037] forcedeth 0000:00:0a.0: setting latency timer to 64
> [    1.586526] forcedeth 0000:00:0a.0: ifname eth0, PHY OUI 0x732 @ 3, addr 00:26:18:40:21:61
> [    1.586542] forcedeth 0000:00:0a.0: highdma csum pwrctl gbit lnktim msi desc-v3
> 
> modprobe 8021q
> 
> - network still works properly, packets are comming not marked at all.
> 
> ip li add link eth0 name vl6 type vlan id 6
> 
> - from this moment massive packetdrop starting to happen, almost half of the *incoming* packets are shown in tcpdump as 
> 14:15:52.859296 00:13:f7:1e:fe:e4 > 00:26:18:40:21:61, ethertype 802.1Q (0x8100), length 102: vlan 64, p 3, ethertype IPv4, [|ip]
> 14:15:56.869572 00:13:f7:1e:fe:e4 > 00:26:18:40:21:61, ethertype 802.1Q (0x8100), length 102: vlan 2112, p 7, ethertype IPv4, [|ip]
> 
> mostly only these two tags appears (64 & 2112). Moreover this happens as on native vlan level (pure ethernet) so on tagged subinterface (as if qinq double tagging) for properly tagged with ID 6 incomming packets.
> 
> I've tried disabling all offloads:
> 
> Offload parameters for eth0:
> rx-checksumming: off
> tx-checksumming: off
> scatter-gather: off
> tcp-segmentation-offload: off
> udp-fragmentation-offload: off
> generic-segmentation-offload: off
> generic-receive-offload: off
> large-receive-offload: off
> rx-vlan-offload: off
> tx-vlan-offload: off
> ntuple-filters: off
> receive-hashing: off
> 
> - doesn't have any effect.
> Once executing 
> ip li del vl6 type vlan
> misterious tags disappear and everything works smoothly. Don't know who injects that garbage into frames - 8021q or forcedeth driver :(
> Any ideas or suggestions to narrow the problem down?
> 
> Additional data.
> Link level data dump example for broken frame:
> 12:35:32.175523 00:13:f7:1e:fe:e4 > 00:26:18:40:21:61, ethertype 802.1Q (0x8100), length 102: vlan 2112, p 2, ethertype IPv4, [|ip]
>         0x0000:  0026 1840 2161 0013 f71e fee4 8100 4840
>         0x0010:  0800 4500 0054 7a12 0000 4001 eb0f
> 0x0C-0D - TPID: ethertype 802.1Q (0x8100) 
> 0x0E-0F - TCI (0100100001000000) PCP 010, CFI 0, VID 100001000000/0x840/2112
> 0x10-11 - ethertype IPv4
> normal ping reply follows, which appears untagged in 50% cases with vlan configured and 100% cases without.
> 
> Interface is plugged into openwrt box into non-switched (wan) gigabit port with vid 6 subinterface configured.
> 

What kernel version are you using ?


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