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  * Version:     $Id: protocol.c,v 1.14 2001/05/18 02:25:49 davem Exp $
   9  *
  10  * Authors:     Ross Biro
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *
  13  * Fixes:
  14  *              Alan Cox        : Ahah! udp icmp errors don't work because
  15  *                                udp_err is never called!
  16  *              Alan Cox        : Added new fields for init and ready for
  17  *                                proper fragmentation (_NO_ 4K limits!)
  18  *              Richard Colella : Hang on hash collision
  19  *              Vince Laviano   : Modified inet_del_protocol() to correctly
  20  *                                maintain copy bit.
  21  *
  22  *              This program is free software; you can redistribute it and/or
  23  *              modify it under the terms of the GNU General Public License
  24  *              as published by the Free Software Foundation; either version
  25  *              2 of the License, or (at your option) any later version.
  26  */
  27
  28 #include <asm/uaccess.h>
  29 #include <asm/system.h>
  30 #include <linux/module.h>
  31 #include <linux/types.h>
  32 #include <linux/kernel.h>
  33 #include <linux/string.h>
  34 #include <linux/socket.h>
  35 #include <linux/in.h>
  36 #include <linux/inet.h>
  37 #include <linux/netdevice.h>
  38 #include <linux/timer.h>
  39 #include <net/ip.h>
  40 #include <net/protocol.h>
  41 #include <linux/skbuff.h>
  42 #include <net/sock.h>
  43 #include <net/icmp.h>
  44 #include <net/udp.h>
  45 #include <net/ipip.h>
  46 #include <linux/igmp.h>
  47
  48 struct net_protocol *inet_protos[MAX_INET_PROTOS] ____cacheline_aligned_in_smp;
  49 static DEFINE_SPINLOCK(inet_proto_lock);
  50
  51 /*
  52  *      Add a protocol handler to the hash tables
  53  */
  54
  55 int inet_add_protocol(struct net_protocol *prot, unsigned char protocol)
  56 {
  57         int hash, ret;
  58
  59         hash = protocol & (MAX_INET_PROTOS - 1);
  60
  61         spin_lock_bh(&inet_proto_lock);
  62         if (inet_protos[hash]) {
  63                 ret = -1;
  64         } else {
  65                 inet_protos[hash] = prot;
  66                 ret = 0;
  67         }
  68         spin_unlock_bh(&inet_proto_lock);
  69
  70         return ret;
  71 }
  72
  73 /*
  74  *      Remove a protocol from the hash tables.
  75  */
  76
  77 int inet_del_protocol(struct net_protocol *prot, unsigned char protocol)
  78 {
  79         int hash, ret;
  80
  81         hash = protocol & (MAX_INET_PROTOS - 1);
  82
  83         spin_lock_bh(&inet_proto_lock);
  84         if (inet_protos[hash] == prot) {
  85                 inet_protos[hash] = NULL;
  86                 ret = 0;
  87         } else {
  88                 ret = -1;
  89         }
  90         spin_unlock_bh(&inet_proto_lock);
  91
  92         synchronize_net();
  93
  94         return ret;
  95 }
  96
  97 EXPORT_SYMBOL(inet_add_protocol);
  98 EXPORT_SYMBOL(inet_del_protocol);