linux/net/ipv4/protocol.c

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/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* INET protocol dispatch tables.
*
* Authors: Ross Biro
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
*
* Fixes:
* Alan Cox : Ahah! udp icmp errors don't work because
* udp_err is never called!
* Alan Cox : Added new fields for init and ready for
* proper fragmentation (_NO_ 4K limits!)
* Richard Colella : Hang on hash collision
* Vince Laviano : Modified inet_del_protocol() to correctly
* maintain copy bit.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/cache.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/spinlock.h>
#include <net/protocol.h>
const struct net_protocol __rcu *inet_protos[MAX_INET_PROTOS] __read_mostly;
/*
* Add a protocol handler to the hash tables
*/
int inet_add_protocol(const struct net_protocol *prot, unsigned char protocol)
{
int hash = protocol & (MAX_INET_PROTOS - 1);
return !cmpxchg((const struct net_protocol **)&inet_protos[hash],
NULL, prot) ? 0 : -1;
}
EXPORT_SYMBOL(inet_add_protocol);
/*
* Remove a protocol from the hash tables.
*/
int inet_del_protocol(const struct net_protocol *prot, unsigned char protocol)
{
int ret, hash = protocol & (MAX_INET_PROTOS - 1);
ret = (cmpxchg((const struct net_protocol **)&inet_protos[hash],
prot, NULL) == prot) ? 0 : -1;
synchronize_net();
return ret;
}
EXPORT_SYMBOL(inet_del_protocol);