Hi James,
Quoting James Morris:
| On Wed, 23 Aug 2006, [email protected] wrote:
|
| > +void __init udplite4_register(void)
| > +{
| > + if (proto_register(&udplite_prot, 1))
| > + goto out_register_err;
| > +
| > + if (inet_add_protocol(&udplite_protocol, IPPROTO_UDPLITE) < 0)
| > + goto out_unregister_proto;
| > +
| > + inet_register_protosw(&udplite4_protosw);
| > +
| > + return;
| > +
| > +out_unregister_proto:
| > + proto_unregister(&udplite_prot);
| > +out_register_err:
| > + printk(KERN_ERR "udplite4_register: Cannot add UDP-Lite protocol\n");
| > +}
|
| Other protocols & network components call panic() if they fail during boot
| initialization. Not sure if this is a great thing, but it raises the
| issue of whether udp-lite should remain consistent here.
The behaviour is consistent (modulo loglevel) with inet_init()
of net/ipv4/af_inet.c:
// ...
rc = proto_register(&udp_prot, 1);
if (rc)
goto out_unregister_tcp_proto;
// ...
if (inet_add_protocol(&udp_protocol, IPPROTO_UDP) < 0)
printk(KERN_CRIT "inet_init: Cannot add UDP protocol\n");
if (inet_add_protocol(&tcp_protocol, IPPROTO_TCP) < 0)
printk(KERN_CRIT "inet_init: Cannot add TCP protocol\n");
// ...
for (q = inetsw_array; q < &inetsw_array[INETSW_ARRAY_LEN]; ++q)
inet_register_protosw(q);
// ...
/* UDP Lite is called here, but the code of udplite4_register()
* could as well be put in place within inet_init() */
udplite4_register();
But your question raises another:
* if TCP cannot init, there is no layer-4 protocol
* if UDP cannot register, TCP is unregistered also
* if RAW cannot register, only UDP is unregistered, but not TCP
>From that I could not deduct a rule what would happen if UDP-Lite failed
to register. If control had reached that above point, it means that all
other protocols have already successfully registered -- if then UDP-Lite
could not register and called a panic(), it would abort the remainder of the
stack.
So how should the code be integrated:
(a) following the same scheme as in af_inet.c (like f.e. raw_prot ) or
(b) keep separate initialisation (as it is used e.g. in net/dccp/ipv4, dccp_v4_init())
(c) ... ?
Gerrit
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