netdev - Re: [PATCH] be2net: Adding support for 802.1ad (q-in-q mode)

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Message-ID: <20090723100533.GB3172@serverengines.com>
Date:	Thu, 23 Jul 2009 15:35:34 +0530
From:	Sarveshwar Bandi <sarveshwarb@...verengines.com>
To:	Patrick McHardy <kaber@...sh.net>
Cc:	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH] be2net: Adding support for 802.1ad (q-in-q mode)

On 23/07/09 11:48 +0200, Patrick McHardy wrote:
> Sarveshwar Bandi wrote:
> > On 23/07/09 11:25 +0200, Patrick McHardy wrote:
> >> Sarveshwar Bandi wrote:
> >>> On 23/07/09 11:07 +0200, Patrick McHardy wrote:
> >>>>> Patch has code to check if the controller is in q-in-q mode. When the packet
> >>>>> has two vids, only the inner vid is passed onto the stack. The stack is never
> >>>>> made aware of the outer vid.
> >>>> But you're still using the outer VLAN group when passing the packet to
> >>>> the VLAN code, so the association to the correct VLAN device can't work.
> >>> In the case where packet comes with two vlan ids, the rx descriptor contains
> >>> the inner vlan id and qnq is set to 1, the driver indicates this vid to the
> >>> stack.
> >>> In the case where packet comes with single vlan id, the rx descriptor
> >>> contains the outer vlan id and qnq is set to 0, the driver indicates this
> >>> packet as a non-vlan packet to the stack by calling netif_receive_skb.
> >> I understand that. But the driver does:
> >>
> >> 	if (vtp) {
> >> 		if (!adapter->vlan_grp || adapter->num_vlans == 0) {
> >> 			kfree_skb(skb);
> >> 			return;
> >> 		}
> >> 		vid = AMAP_GET_BITS(struct amap_eth_rx_compl, vlan_tag, rxcp);
> >> 		vid = be16_to_cpu(vid);
> >> 		vlan_hwaccel_receive_skb(skb, adapter->vlan_grp, vid);
> >> 	}
> >>
> >> adapter->vlan_grp will always be the VLAN group associated directly with
> >> the device, which is the group for the outer tag, not the inner one. So
> >> this can't properly associate packets with the correct VLAN device.
> >>
> > In this case, vid is the inner vlan id in the packet. This is also the
> > vlan id configured by vconfig. 
> 
> So where does the outer tag come from then? Please provide an example
> how to configure this using Q-in-Q.
> 
The outer vlan is totally transparent to the host. It is used by the NIC 
to demux packets across multiple pci network functions. Currently the 
outer vlan tags are configured on the NIC by OEM provided utilities.
> > In the other case where packet had a single vlan tag, the following code
> > will set vlanf to 0 (vtp now renamed to vlanf in the patch) and will be
> > indicated as a non-vlan packet.
> >        if (adapter->qnq && !qnq)
> >                vlanf = 0;
> 
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