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

["David S. Miller" <davem@xxxxxxxxxx>]

On Wed, 08 Oct 2003 09:34:20 -0700
Ben Greear <greearb@xxxxxxxxxxxxxxx> 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.