llc_core.c

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/*
 * llc_core.c - Minimum needed routines for sap handling and module init/exit
 *
 * Copyright (c) 1997 by Procom Technology, Inc.
 *       2001-2003 by Arnaldo Carvalho de Melo <[email protected]>
 *
 * This program can be redistributed or modified under the terms of the
 * GNU General Public License as published by the Free Software Foundation.
 * This program is distributed without any warranty or implied warranty
 * of merchantability or fitness for a particular purpose.
 *
 * See the GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/init.h>
#include <net/net_namespace.h>
#include <net/llc.h>

LIST_HEAD(llc_sap_list);
DEFINE_SPINLOCK(llc_sap_list_lock);

static struct llc_sap *llc_sap_alloc(void)
{
    struct llc_sap *sap = kzalloc(sizeof(*sap), GFP_ATOMIC);
    int i;

    if (sap) {
        /* sap->laddr.mac - leave as a null, it's filled by bind */
        sap->state = LLC_SAP_STATE_ACTIVE;
        spin_lock_init(&sap->sk_lock);
        for (i = 0; i < LLC_SK_LADDR_HASH_ENTRIES; i++)
            INIT_HLIST_NULLS_HEAD(&sap->sk_laddr_hash[i], i);
        atomic_set(&sap->refcnt, 1);
    }
    return sap;
}

static struct llc_sap *__llc_sap_find(unsigned char sap_value)
{
    struct llc_sap* sap;

    list_for_each_entry(sap, &llc_sap_list, node)
        if (sap->laddr.lsap == sap_value)
            goto out;
    sap = NULL;
out:
    return sap;
}

struct llc_sap *llc_sap_find(unsigned char sap_value)
{
    struct llc_sap *sap;

    rcu_read_lock_bh();
    sap = __llc_sap_find(sap_value);
    if (sap)
        llc_sap_hold(sap);
    rcu_read_unlock_bh();
    return sap;
}

struct llc_sap *llc_sap_open(unsigned char lsap,
                 int (*func)(struct sk_buff *skb,
                     struct net_device *dev,
                     struct packet_type *pt,
                     struct net_device *orig_dev))
{
    struct llc_sap *sap = NULL;

    spin_lock_bh(&llc_sap_list_lock);
    if (__llc_sap_find(lsap)) /* SAP already exists */
        goto out;
    sap = llc_sap_alloc();
    if (!sap)
        goto out;
    sap->laddr.lsap = lsap;
    sap->rcv_func   = func;
    list_add_tail_rcu(&sap->node, &llc_sap_list);
out:
    spin_unlock_bh(&llc_sap_list_lock);
    return sap;
}

void llc_sap_close(struct llc_sap *sap)
{
    WARN_ON(sap->sk_count);

    spin_lock_bh(&llc_sap_list_lock);
    list_del_rcu(&sap->node);
    spin_unlock_bh(&llc_sap_list_lock);

    synchronize_rcu();

    kfree(sap);
}

static struct packet_type llc_packet_type __read_mostly = {
    .type = cpu_to_be16(ETH_P_802_2),
    .func = llc_rcv,
};

static struct packet_type llc_tr_packet_type __read_mostly = {
    .type = cpu_to_be16(ETH_P_TR_802_2),
    .func = llc_rcv,
};

static int __init llc_init(void)
{
    dev_add_pack(&llc_packet_type);
    dev_add_pack(&llc_tr_packet_type);
    return 0;
}

static void __exit llc_exit(void)
{
    dev_remove_pack(&llc_packet_type);
    dev_remove_pack(&llc_tr_packet_type);
}

module_init(llc_init);
module_exit(llc_exit);

EXPORT_SYMBOL(llc_sap_list);
EXPORT_SYMBOL(llc_sap_list_lock);
EXPORT_SYMBOL(llc_sap_find);
EXPORT_SYMBOL(llc_sap_open);
EXPORT_SYMBOL(llc_sap_close);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Procom 1997, Jay Schullist 2001, Arnaldo C. Melo 2001-2003");
MODULE_DESCRIPTION("LLC IEEE 802.2 core support");