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From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH 1/2] NET: Re-add VLAN tag for devices incapable of
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Date: Mon, 05 Nov 2007 15:15:44 -0800 (PST)
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From: Patrick McHardy <kaber@trash.net>
Date: Mon, 05 Nov 2007 19:00:19 +0100

> This looks like a rather expensive operation for the unlikely case
> that packets will be received by a packet socket. IMO it should only
> be reconstructed if actually needed, by af_packet itself.

Completely agreed.  We should not do this by default when %99
of the networking stack simply does not care about this.

> As we discussed some time back storing the VLAN tag in the CB on
> TX clashes with other users of the CB like qdiscs, so we need a
> new field in the skb for this anyway.

Someone will have to find a way to remove some other fields in
sk_buff before I'm going to allow more space to be eaten up
by this completely fringe case feature.