Re: [PATCH] af_pppox: create module infrastructure for protocol modules

   From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxx>
   Date: Tue, 29 Apr 2003 03:12:27 -0300

        Max, take a look and see if this same approach can be used in
   bluetooth, I bet it can, its just a matter of not using struct
   net_proto_family for bt_proto, just like pppox already was doing
   before my changes :-)

Something similar can be done for ipv4/ipv6 by adding a struct module
*owner member to struct inet_protosw etc. etc.

Although the idea is conceptually sound, you miss one crucial thing.
Such struct sock's reference _TWO_ modules, the "PPPOE" module
and the "PPPOX" module.

So in the TCP/UDP/SCTP example case, a struct sock references the
TCP/UDP/SCTP module _AND_ the ipv4/ipv6 module.

So what we'll need to do is use two owner pointers in struct sock,
one for propagating the "struct socket" owner, and one for the
"sub-protocol".

        struct module   *owner;
        struct module   *sub_owner;