Re: [net-next-2.6 PATCH] macvlan: add VLAN filters to lowerdev

[David Miller <davem@davemloft.net>]

From: John Fastabend <john.r.fastabend@intel.com>
Date: Mon, 06 Jun 2011 15:44:39 -0700

> On 6/6/2011 3:03 PM, David Miller wrote:
>> From: John Fastabend <john.r.fastabend@intel.com>
>> Date: Mon, 06 Jun 2011 07:27:16 -0700
>> 
>>> Stacking VLANs on top of the macvlan device does not
>>> work if the lowerdev device is using vlan filters set
>>> by NETIF_F_HW_VLAN_FILTER. Add ndo ops to pass vlan
>>> calls to lowerdev.
>>>
>>> Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
>> 
>> I think this might have unintended side-effects.
>> 
>> Much of the VLAN code makes decisions based upon whether these
>> ops are NULL or not.
>> 
>> Now, no matter what is implemented in the lower device, the VLAN
>> code will see them non-NULL in the macvlan device.
> 
> I would expect these decisions to be wrapped in the feature flag
> like this,
> 
>         if (vlan_id && (real_dev->features & NETIF_F_HW_VLAN_FILTER))
>                 ops->ndo_vlan_rx_kill_vid(real_dev, vlan_id);
> 
> Although grep found two call sites not wrapped,
 ...
> I could wrap these in feature flag checks as well but I see no harm
> in letting these fall through to the macvlan driver and failing.

Fair enough, patch applied.