1/*
2 * llc_core.c - Minimum needed routines for sap handling and module init/exit
3 *
4 * Copyright (c) 1997 by Procom Technology, Inc.
5 * 		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6 *
7 * This program can be redistributed or modified under the terms of the
8 * GNU General Public License as published by the Free Software Foundation.
9 * This program is distributed without any warranty or implied warranty
10 * of merchantability or fitness for a particular purpose.
11 *
12 * See the GNU General Public License for more details.
13 */
14
15#include <linux/module.h>
16#include <linux/interrupt.h>
17#include <linux/if_ether.h>
18#include <linux/netdevice.h>
19#include <linux/slab.h>
20#include <linux/string.h>
21#include <linux/init.h>
22#include <net/net_namespace.h>
23#include <net/llc.h>
24
25LIST_HEAD(llc_sap_list);
26static DEFINE_SPINLOCK(llc_sap_list_lock);
27
28/**
29 *	llc_sap_alloc - allocates and initializes sap.
30 *
31 *	Allocates and initializes sap.
32 */
33static struct llc_sap *llc_sap_alloc(void)
34{
35	struct llc_sap *sap = kzalloc(sizeof(*sap), GFP_ATOMIC);
36	int i;
37
38	if (sap) {
39		/* sap->laddr.mac - leave as a null, it's filled by bind */
40		sap->state = LLC_SAP_STATE_ACTIVE;
41		spin_lock_init(&sap->sk_lock);
42		for (i = 0; i < LLC_SK_LADDR_HASH_ENTRIES; i++)
43			INIT_HLIST_NULLS_HEAD(&sap->sk_laddr_hash[i], i);
44		refcount_set(&sap->refcnt, 1);
45	}
46	return sap;
47}
48
49static struct llc_sap *__llc_sap_find(unsigned char sap_value)
50{
51	struct llc_sap *sap;
52
53	list_for_each_entry(sap, &llc_sap_list, node)
54		if (sap->laddr.lsap == sap_value)
55			goto out;
56	sap = NULL;
57out:
58	return sap;
59}
60
61/**
62 *	llc_sap_find - searches a SAP in station
63 *	@sap_value: sap to be found
64 *
65 *	Searches for a sap in the sap list of the LLC's station upon the sap ID.
66 *	If the sap is found it will be refcounted and the user will have to do
67 *	a llc_sap_put after use.
68 *	Returns the sap or %NULL if not found.
69 */
70struct llc_sap *llc_sap_find(unsigned char sap_value)
71{
72	struct llc_sap *sap;
73
74	rcu_read_lock_bh();
75	sap = __llc_sap_find(sap_value);
76	if (!sap || !llc_sap_hold_safe(sap))
77		sap = NULL;
78	rcu_read_unlock_bh();
79	return sap;
80}
81
82/**
83 *	llc_sap_open - open interface to the upper layers.
84 *	@lsap: SAP number.
85 *	@func: rcv func for datalink protos
86 *
87 *	Interface function to upper layer. Each one who wants to get a SAP
88 *	(for example NetBEUI) should call this function. Returns the opened
89 *	SAP for success, NULL for failure.
90 */
91struct llc_sap *llc_sap_open(unsigned char lsap,
92			     int (*func)(struct sk_buff *skb,
93					 struct net_device *dev,
94					 struct packet_type *pt,
95					 struct net_device *orig_dev))
96{
97	struct llc_sap *sap = NULL;
98
99	spin_lock_bh(&llc_sap_list_lock);
100	if (__llc_sap_find(lsap)) /* SAP already exists */
101		goto out;
102	sap = llc_sap_alloc();
103	if (!sap)
104		goto out;
105	sap->laddr.lsap = lsap;
106	sap->rcv_func	= func;
107	list_add_tail_rcu(&sap->node, &llc_sap_list);
108out:
109	spin_unlock_bh(&llc_sap_list_lock);
110	return sap;
111}
112
113/**
114 *	llc_sap_close - close interface for upper layers.
115 *	@sap: SAP to be closed.
116 *
117 *	Close interface function to upper layer. Each one who wants to
118 *	close an open SAP (for example NetBEUI) should call this function.
119 * 	Removes this sap from the list of saps in the station and then
120 * 	frees the memory for this sap.
121 */
122void llc_sap_close(struct llc_sap *sap)
123{
124	WARN_ON(sap->sk_count);
125
126	spin_lock_bh(&llc_sap_list_lock);
127	list_del_rcu(&sap->node);
128	spin_unlock_bh(&llc_sap_list_lock);
129
130	kfree_rcu(sap, rcu);
131}
132
133static struct packet_type llc_packet_type __read_mostly = {
134	.type = cpu_to_be16(ETH_P_802_2),
135	.func = llc_rcv,
136};
137
138static int __init llc_init(void)
139{
140	dev_add_pack(&llc_packet_type);
141	return 0;
142}
143
144static void __exit llc_exit(void)
145{
146	dev_remove_pack(&llc_packet_type);
147}
148
149module_init(llc_init);
150module_exit(llc_exit);
151
152EXPORT_SYMBOL(llc_sap_list);
153EXPORT_SYMBOL(llc_sap_find);
154EXPORT_SYMBOL(llc_sap_open);
155EXPORT_SYMBOL(llc_sap_close);
156
157MODULE_LICENSE("GPL");
158MODULE_AUTHOR("Procom 1997, Jay Schullist 2001, Arnaldo C. Melo 2001-2003");
159MODULE_DESCRIPTION("LLC IEEE 802.2 core support");
160