llc_core.c revision 9f09243890a4e7d2e06d40b56f26a64f88c6ec8b 
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);
26DEFINE_RWLOCK(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
37	if (sap) {
38		/* sap->laddr.mac - leave as a null, it's filled by bind */
39		sap->state = LLC_SAP_STATE_ACTIVE;
40		rwlock_init(&sap->sk_list.lock);
41		atomic_set(&sap->refcnt, 1);
42	}
43	return sap;
44}
45
46/**
47 *	llc_add_sap - add sap to station list
48 *	@sap: Address of the sap
49 *
50 *	Adds a sap to the LLC's station sap list.
51 */
52static void llc_add_sap(struct llc_sap *sap)
53{
54	list_add_tail(&sap->node, &llc_sap_list);
55}
56
57/**
58 *	llc_del_sap - del sap from station list
59 *	@sap: Address of the sap
60 *
61 *	Removes a sap to the LLC's station sap list.
62 */
63static void llc_del_sap(struct llc_sap *sap)
64{
65	write_lock_bh(&llc_sap_list_lock);
66	list_del(&sap->node);
67	write_unlock_bh(&llc_sap_list_lock);
68}
69
70static struct llc_sap *__llc_sap_find(unsigned char sap_value)
71{
72	struct llc_sap* sap;
73
74	list_for_each_entry(sap, &llc_sap_list, node)
75		if (sap->laddr.lsap == sap_value)
76			goto out;
77	sap = NULL;
78out:
79	return sap;
80}
81
82/**
83 *	llc_sap_find - searchs a SAP in station
84 *	@sap_value: sap to be found
85 *
86 *	Searchs for a sap in the sap list of the LLC's station upon the sap ID.
87 *	If the sap is found it will be refcounted and the user will have to do
88 *	a llc_sap_put after use.
89 *	Returns the sap or %NULL if not found.
90 */
91struct llc_sap *llc_sap_find(unsigned char sap_value)
92{
93	struct llc_sap* sap;
94
95	read_lock_bh(&llc_sap_list_lock);
96	sap = __llc_sap_find(sap_value);
97	if (sap)
98		llc_sap_hold(sap);
99	read_unlock_bh(&llc_sap_list_lock);
100	return sap;
101}
102
103/**
104 *	llc_sap_open - open interface to the upper layers.
105 *	@lsap: SAP number.
106 *	@func: rcv func for datalink protos
107 *
108 *	Interface function to upper layer. Each one who wants to get a SAP
109 *	(for example NetBEUI) should call this function. Returns the opened
110 *	SAP for success, NULL for failure.
111 */
112struct llc_sap *llc_sap_open(unsigned char lsap,
113			     int (*func)(struct sk_buff *skb,
114					 struct net_device *dev,
115					 struct packet_type *pt,
116					 struct net_device *orig_dev))
117{
118	struct llc_sap *sap = NULL;
119
120	write_lock_bh(&llc_sap_list_lock);
121	if (__llc_sap_find(lsap)) /* SAP already exists */
122		goto out;
123	sap = llc_sap_alloc();
124	if (!sap)
125		goto out;
126	sap->laddr.lsap = lsap;
127	sap->rcv_func	= func;
128	llc_add_sap(sap);
129out:
130	write_unlock_bh(&llc_sap_list_lock);
131	return sap;
132}
133
134/**
135 *	llc_sap_close - close interface for upper layers.
136 *	@sap: SAP to be closed.
137 *
138 *	Close interface function to upper layer. Each one who wants to
139 *	close an open SAP (for example NetBEUI) should call this function.
140 * 	Removes this sap from the list of saps in the station and then
141 * 	frees the memory for this sap.
142 */
143void llc_sap_close(struct llc_sap *sap)
144{
145	WARN_ON(!hlist_empty(&sap->sk_list.list));
146	llc_del_sap(sap);
147	kfree(sap);
148}
149
150static struct packet_type llc_packet_type = {
151	.type = __constant_htons(ETH_P_802_2),
152	.func = llc_rcv,
153};
154
155static struct packet_type llc_tr_packet_type = {
156	.type = __constant_htons(ETH_P_TR_802_2),
157	.func = llc_rcv,
158};
159
160static int __init llc_init(void)
161{
162	struct net_device *dev;
163
164	dev = first_net_device(&init_net);
165	if (dev != NULL)
166		dev = next_net_device(dev);
167
168	dev_add_pack(&llc_packet_type);
169	dev_add_pack(&llc_tr_packet_type);
170	return 0;
171}
172
173static void __exit llc_exit(void)
174{
175	dev_remove_pack(&llc_packet_type);
176	dev_remove_pack(&llc_tr_packet_type);
177}
178
179module_init(llc_init);
180module_exit(llc_exit);
181
182EXPORT_SYMBOL(llc_sap_list);
183EXPORT_SYMBOL(llc_sap_list_lock);
184EXPORT_SYMBOL(llc_sap_find);
185EXPORT_SYMBOL(llc_sap_open);
186EXPORT_SYMBOL(llc_sap_close);
187
188MODULE_LICENSE("GPL");
189MODULE_AUTHOR("Procom 1997, Jay Schullist 2001, Arnaldo C. Melo 2001-2003");
190MODULE_DESCRIPTION("LLC IEEE 802.2 core support");
191