/*
   * 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);