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, <[email protected]>
 *
 * 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)
{
    return !cmpxchg((const struct net_protocol **)&inet_protos[protocol],
            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;

    ret = (cmpxchg((const struct net_protocol **)&inet_protos[protocol],
               prot, NULL) == prot) ? 0 : -1;

    synchronize_net();

    return ret;
}
EXPORT_SYMBOL(inet_del_protocol);