/*
 * 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 <acme@conectiva.com.br>
 *
 * 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);
static DEFINE_SPINLOCK(llc_sap_list_lock);

/**
 *      llc_sap_alloc - allocates and initializes sap.
 *
 *      Allocates and initializes sap.
 */
static struct llc_sap *llc_sap_alloc(void)
{
        struct llc_sap *sap = kzalloc_obj(*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);
                refcount_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;
}

/**
 *      llc_sap_find - searches a SAP in station
 *      @sap_value: sap to be found
 *
 *      Searches for a sap in the sap list of the LLC's station upon the sap ID.
 *      If the sap is found it will be refcounted and the user will have to do
 *      a llc_sap_put after use.
 *      Returns the sap or %NULL if not found.
 */
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_safe(sap))
                sap = NULL;
        rcu_read_unlock_bh();
        return sap;
}

/**
 *      llc_sap_open - open interface to the upper layers.
 *      @lsap: SAP number.
 *      @func: rcv func for datalink protos
 *
 *      Interface function to upper layer. Each one who wants to get a SAP
 *      (for example NetBEUI) should call this function. Returns the opened
 *      SAP for success, NULL for failure.
 */
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;
}

/**
 *      llc_sap_close - close interface for upper layers.
 *      @sap: SAP to be closed.
 *
 *      Close interface function to upper layer. Each one who wants to
 *      close an open SAP (for example NetBEUI) should call this function.
 *      Removes this sap from the list of saps in the station and then
 *      frees the memory for this 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);

        kfree_rcu(sap, rcu);
}

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

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

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

module_init(llc_init);
module_exit(llc_exit);

EXPORT_SYMBOL(llc_sap_list);
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");