Re: [PATCH 1/4] veth: move loopback logic to common location

From: Patrick McHardy
Date: Tue Nov 24 2009 - 05:17:20 EST


Arnd Bergmann wrote:
> On Tuesday 24 November 2009 09:51:19 Patrick McHardy wrote:
>>> + skb_dst_drop(skb);
>>> + skb->tstamp.tv64 = 0;
>>> + skb->pkt_type = PACKET_HOST;
>>> + skb->protocol = eth_type_trans(skb, dev);
>>> + skb->mark = 0;
>> skb->mark clearing should stay private to veth since its usually
>> supposed to stay intact. The only exception is packets crossing
>> namespaces, where they should appear like a freshly received skbs.
>
> But isn't that what we want in macvlan as well when we're
> forwarding from one downstream interface to another?

In the TX direction you can use the mark for TC classification
on the underlying device.

> I did all my testing with macvlan interfaces in separate namespaces
> communicating with each other, so I'd assume that we should always
> clear skb->mark and skb->dst in this function.

Good point, in that case we probably should clear it as well. But
in the non-namespace case the TC classification currently works and
this is consistent with any other virtual device driver, so it
should continue to work.
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