question about bridge code

[lkcd <kernelluck@xxxxxxx>]

br_nf_forward_ip() {

    parent = bridge_parent(out);

    NF_HOOK(pf, NF_INET_FORWARD, skb, brnf_get_logical_dev(skb, in), parent, br_nf_forward_finish);

}

 

here, i suppose pf = NFPROTO_IPV4,    i think  the return of brnf_get_logical_dev(skb, in) equals parent ?

 

then when calls iptable_filter_hook to match iptables rules , how to distinct in and out devices?

 

thanks