LXR linux/net/ipv4/protocol.c

   1/*
   2 * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3 *              operating system.  INET is implemented using the  BSD Socket
   4 *              interface as the means of communication with the user level.
   5 *
   6 *              INET protocol dispatch tables.
   7 *
   8 * Authors:     Ross Biro
   9 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  10 *
  11 * Fixes:
  12 *              Alan Cox        : Ahah! udp icmp errors don't work because
  13 *                                udp_err is never called!
  14 *              Alan Cox        : Added new fields for init and ready for
  15 *                                proper fragmentation (_NO_ 4K limits!)
  16 *              Richard Colella : Hang on hash collision
  17 *              Vince Laviano   : Modified inet_del_protocol() to correctly
  18 *                                maintain copy bit.
  19 *
  20 *              This program is free software; you can redistribute it and/or
  21 *              modify it under the terms of the GNU General Public License
  22 *              as published by the Free Software Foundation; either version
  23 *              2 of the License, or (at your option) any later version.
  24 */
  25#include <linux/cache.h>
  26#include <linux/module.h>
  27#include <linux/netdevice.h>
  28#include <linux/spinlock.h>
  29#include <net/protocol.h>
  30
  31const struct net_protocol __rcu *inet_protos[MAX_INET_PROTOS] __read_mostly;
  32const struct net_offload __rcu *inet_offloads[MAX_INET_PROTOS] __read_mostly;
  33
  34/*
  35 *      Add a protocol handler to the hash tables
  36 */
  37
  38int inet_add_protocol(const struct net_protocol *prot, unsigned char protocol)
  39{
  40        if (!prot->netns_ok) {
  41                pr_err("Protocol %u is not namespace aware, cannot register.\n",
  42                        protocol);
  43                return -EINVAL;
  44        }
  45
  46        return !cmpxchg((const struct net_protocol **)&inet_protos[protocol],
  47                        NULL, prot) ? 0 : -1;
  48}
  49EXPORT_SYMBOL(inet_add_protocol);
  50
  51int inet_add_offload(const struct net_offload *prot, unsigned char protocol)
  52{
  53        return !cmpxchg((const struct net_offload **)&inet_offloads[protocol],
  54                        NULL, prot) ? 0 : -1;
  55}
  56EXPORT_SYMBOL(inet_add_offload);
  57
  58/*
  59 *      Remove a protocol from the hash tables.
  60 */
  61
  62int inet_del_protocol(const struct net_protocol *prot, unsigned char protocol)
  63{
  64        int ret;
  65
  66        ret = (cmpxchg((const struct net_protocol **)&inet_protos[protocol],
  67                       prot, NULL) == prot) ? 0 : -1;
  68
  69        synchronize_net();
  70
  71        return ret;
  72}
  73EXPORT_SYMBOL(inet_del_protocol);
  74
  75int inet_del_offload(const struct net_offload *prot, unsigned char protocol)
  76{
  77        int ret;
  78
  79        ret = (cmpxchg((const struct net_offload **)&inet_offloads[protocol],
  80                       prot, NULL) == prot) ? 0 : -1;
  81
  82        synchronize_net();
  83
  84        return ret;
  85}
  86EXPORT_SYMBOL(inet_del_offload);
  87