Subject: Re: [Bridge] RE: [VLAN] Re: [PATCH/RFC] Let {ip, arp}tables "see" bridged VLAN tagged{I,AR}P packets

From: "David S. Miller" <[email-masked]>
Date: Wed, 8 Oct 2003 09:33:54 -0700

On Wed, 08 Oct 2003 09:34:20 -0700
Ben Greear <[email-masked]> wrote:

> So, what good is skb_share_check then?
> Maybe we should have a skb_share_or_cloned_check() ?

What input handlers are supposed to do is first:

	skb = skb_share_check(...);

then look at packet contents etc., then if they need to write
to the header do something like skb_cow().

The best example, as usual, is ipv4 input.  Look at how ip_rcv()
makes sure it can safely get at the packet header parts it needs
to parse, then look at ip_forward and how it cows the IPV4 header
so it can modify the TTL field.