Messages in this thread |  | | | From | gerrit@erg ... | | Subject | Re: [RFC][PATCH 1/3] net/ipv4: UDP-Lite extensions | | Date | Wed, 23 Aug 2006 16:03:07 +0100 |
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Hi James,
Quoting James Morris: | On Wed, 23 Aug 2006, gerrit@erg.abdn.ac.uk 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) ... ?
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