net/ipv4/protocol.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              INET protocol dispatch tables.
   8  *
   9  * Authors:     Ross Biro
  10  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  11  *
  12  * Fixes:
  13  *              Alan Cox        : Ahah! udp icmp errors don't work because
  14  *                                udp_err is never called!
  15  *              Alan Cox        : Added new fields for init and ready for
  16  *                                proper fragmentation (_NO_ 4K limits!)
  17  *              Richard Colella : Hang on hash collision
  18  *              Vince Laviano   : Modified inet_del_protocol() to correctly
  19  *                                maintain copy bit.
  20  */
  21 #include <linux/cache.h>
  22 #include <linux/module.h>
  23 #include <linux/netdevice.h>
  24 #include <linux/spinlock.h>
  25 #include <net/protocol.h>
  26
  27 struct net_protocol __rcu *inet_protos[MAX_INET_PROTOS] __read_mostly;
  28 EXPORT_SYMBOL(inet_protos);
  29 const struct net_offload __rcu *inet_offloads[MAX_INET_PROTOS] __read_mostly;
  30 EXPORT_SYMBOL(inet_offloads);
  31
  32 int inet_add_protocol(const struct net_protocol *prot, unsigned char protocol)
  33 {
  34         return !cmpxchg((const struct net_protocol **)&inet_protos[protocol],
  35                         NULL, prot) ? 0 : -1;
  36 }
  37 EXPORT_SYMBOL(inet_add_protocol);
  38
  39 int inet_add_offload(const struct net_offload *prot, unsigned char protocol)
  40 {
  41         return !cmpxchg((const struct net_offload **)&inet_offloads[protocol],
  42                         NULL, prot) ? 0 : -1;
  43 }
  44 EXPORT_SYMBOL(inet_add_offload);
  45
  46 int inet_del_protocol(const struct net_protocol *prot, unsigned char protocol)
  47 {
  48         int ret;
  49
  50         ret = (cmpxchg((const struct net_protocol **)&inet_protos[protocol],
  51                        prot, NULL) == prot) ? 0 : -1;
  52
  53         synchronize_net();
  54
  55         return ret;
  56 }
  57 EXPORT_SYMBOL(inet_del_protocol);
  58
  59 int inet_del_offload(const struct net_offload *prot, unsigned char protocol)
  60 {
  61         int ret;
  62
  63         ret = (cmpxchg((const struct net_offload **)&inet_offloads[protocol],
  64                        prot, NULL) == prot) ? 0 : -1;
  65
  66         synchronize_net();
  67
  68         return ret;
  69 }
  70 EXPORT_SYMBOL(inet_del_offload);