br_fdb.c revision e18b890bb0881bbab6f4f1a6cd20d9c60d66b003 
1/*
2 *	Forwarding database
3 *	Linux ethernet bridge
4 *
5 *	Authors:
6 *	Lennert Buytenhek		<buytenh@gnu.org>
7 *
8 *	$Id: br_fdb.c,v 1.6 2002/01/17 00:57:07 davem Exp $
9 *
10 *	This program is free software; you can redistribute it and/or
11 *	modify it under the terms of the GNU General Public License
12 *	as published by the Free Software Foundation; either version
13 *	2 of the License, or (at your option) any later version.
14 */
15
16#include <linux/kernel.h>
17#include <linux/init.h>
18#include <linux/spinlock.h>
19#include <linux/times.h>
20#include <linux/netdevice.h>
21#include <linux/etherdevice.h>
22#include <linux/jhash.h>
23#include <asm/atomic.h>
24#include "br_private.h"
25
26static struct kmem_cache *br_fdb_cache __read_mostly;
27static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
28		      const unsigned char *addr);
29
30void __init br_fdb_init(void)
31{
32	br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
33					 sizeof(struct net_bridge_fdb_entry),
34					 0,
35					 SLAB_HWCACHE_ALIGN, NULL, NULL);
36}
37
38void __exit br_fdb_fini(void)
39{
40	kmem_cache_destroy(br_fdb_cache);
41}
42
43
44/* if topology_changing then use forward_delay (default 15 sec)
45 * otherwise keep longer (default 5 minutes)
46 */
47static __inline__ unsigned long hold_time(const struct net_bridge *br)
48{
49	return br->topology_change ? br->forward_delay : br->ageing_time;
50}
51
52static __inline__ int has_expired(const struct net_bridge *br,
53				  const struct net_bridge_fdb_entry *fdb)
54{
55	return !fdb->is_static
56		&& time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
57}
58
59static __inline__ int br_mac_hash(const unsigned char *mac)
60{
61	return jhash(mac, ETH_ALEN, 0) & (BR_HASH_SIZE - 1);
62}
63
64static __inline__ void fdb_delete(struct net_bridge_fdb_entry *f)
65{
66	hlist_del_rcu(&f->hlist);
67	br_fdb_put(f);
68}
69
70void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
71{
72	struct net_bridge *br = p->br;
73	int i;
74
75	spin_lock_bh(&br->hash_lock);
76
77	/* Search all chains since old address/hash is unknown */
78	for (i = 0; i < BR_HASH_SIZE; i++) {
79		struct hlist_node *h;
80		hlist_for_each(h, &br->hash[i]) {
81			struct net_bridge_fdb_entry *f;
82
83			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
84			if (f->dst == p && f->is_local) {
85				/* maybe another port has same hw addr? */
86				struct net_bridge_port *op;
87				list_for_each_entry(op, &br->port_list, list) {
88					if (op != p &&
89					    !compare_ether_addr(op->dev->dev_addr,
90								f->addr.addr)) {
91						f->dst = op;
92						goto insert;
93					}
94				}
95
96				/* delete old one */
97				fdb_delete(f);
98				goto insert;
99			}
100		}
101	}
102 insert:
103	/* insert new address,  may fail if invalid address or dup. */
104	fdb_insert(br, p, newaddr);
105
106	spin_unlock_bh(&br->hash_lock);
107}
108
109void br_fdb_cleanup(unsigned long _data)
110{
111	struct net_bridge *br = (struct net_bridge *)_data;
112	unsigned long delay = hold_time(br);
113	int i;
114
115	spin_lock_bh(&br->hash_lock);
116	for (i = 0; i < BR_HASH_SIZE; i++) {
117		struct net_bridge_fdb_entry *f;
118		struct hlist_node *h, *n;
119
120		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
121			if (!f->is_static &&
122			    time_before_eq(f->ageing_timer + delay, jiffies))
123				fdb_delete(f);
124		}
125	}
126	spin_unlock_bh(&br->hash_lock);
127
128	mod_timer(&br->gc_timer, jiffies + HZ/10);
129}
130
131
132void br_fdb_delete_by_port(struct net_bridge *br,
133			   const struct net_bridge_port *p,
134			   int do_all)
135{
136	int i;
137
138	spin_lock_bh(&br->hash_lock);
139	for (i = 0; i < BR_HASH_SIZE; i++) {
140		struct hlist_node *h, *g;
141
142		hlist_for_each_safe(h, g, &br->hash[i]) {
143			struct net_bridge_fdb_entry *f
144				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
145			if (f->dst != p)
146				continue;
147
148			if (f->is_static && !do_all)
149				continue;
150			/*
151			 * if multiple ports all have the same device address
152			 * then when one port is deleted, assign
153			 * the local entry to other port
154			 */
155			if (f->is_local) {
156				struct net_bridge_port *op;
157				list_for_each_entry(op, &br->port_list, list) {
158					if (op != p &&
159					    !compare_ether_addr(op->dev->dev_addr,
160								f->addr.addr)) {
161						f->dst = op;
162						goto skip_delete;
163					}
164				}
165			}
166
167			fdb_delete(f);
168		skip_delete: ;
169		}
170	}
171	spin_unlock_bh(&br->hash_lock);
172}
173
174/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
175struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
176					  const unsigned char *addr)
177{
178	struct hlist_node *h;
179	struct net_bridge_fdb_entry *fdb;
180
181	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
182		if (!compare_ether_addr(fdb->addr.addr, addr)) {
183			if (unlikely(has_expired(br, fdb)))
184				break;
185			return fdb;
186		}
187	}
188
189	return NULL;
190}
191
192/* Interface used by ATM hook that keeps a ref count */
193struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
194					unsigned char *addr)
195{
196	struct net_bridge_fdb_entry *fdb;
197
198	rcu_read_lock();
199	fdb = __br_fdb_get(br, addr);
200	if (fdb)
201		atomic_inc(&fdb->use_count);
202	rcu_read_unlock();
203	return fdb;
204}
205
206static void fdb_rcu_free(struct rcu_head *head)
207{
208	struct net_bridge_fdb_entry *ent
209		= container_of(head, struct net_bridge_fdb_entry, rcu);
210	kmem_cache_free(br_fdb_cache, ent);
211}
212
213/* Set entry up for deletion with RCU  */
214void br_fdb_put(struct net_bridge_fdb_entry *ent)
215{
216	if (atomic_dec_and_test(&ent->use_count))
217		call_rcu(&ent->rcu, fdb_rcu_free);
218}
219
220/*
221 * Fill buffer with forwarding table records in
222 * the API format.
223 */
224int br_fdb_fillbuf(struct net_bridge *br, void *buf,
225		   unsigned long maxnum, unsigned long skip)
226{
227	struct __fdb_entry *fe = buf;
228	int i, num = 0;
229	struct hlist_node *h;
230	struct net_bridge_fdb_entry *f;
231
232	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
233
234	rcu_read_lock();
235	for (i = 0; i < BR_HASH_SIZE; i++) {
236		hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
237			if (num >= maxnum)
238				goto out;
239
240			if (has_expired(br, f))
241				continue;
242
243			if (skip) {
244				--skip;
245				continue;
246			}
247
248			/* convert from internal format to API */
249			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
250			fe->port_no = f->dst->port_no;
251			fe->is_local = f->is_local;
252			if (!f->is_static)
253				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
254			++fe;
255			++num;
256		}
257	}
258
259 out:
260	rcu_read_unlock();
261
262	return num;
263}
264
265static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
266						    const unsigned char *addr)
267{
268	struct hlist_node *h;
269	struct net_bridge_fdb_entry *fdb;
270
271	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
272		if (!compare_ether_addr(fdb->addr.addr, addr))
273			return fdb;
274	}
275	return NULL;
276}
277
278static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
279					       struct net_bridge_port *source,
280					       const unsigned char *addr,
281					       int is_local)
282{
283	struct net_bridge_fdb_entry *fdb;
284
285	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
286	if (fdb) {
287		memcpy(fdb->addr.addr, addr, ETH_ALEN);
288		atomic_set(&fdb->use_count, 1);
289		hlist_add_head_rcu(&fdb->hlist, head);
290
291		fdb->dst = source;
292		fdb->is_local = is_local;
293		fdb->is_static = is_local;
294		fdb->ageing_timer = jiffies;
295	}
296	return fdb;
297}
298
299static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
300		  const unsigned char *addr)
301{
302	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
303	struct net_bridge_fdb_entry *fdb;
304
305	if (!is_valid_ether_addr(addr))
306		return -EINVAL;
307
308	fdb = fdb_find(head, addr);
309	if (fdb) {
310		/* it is okay to have multiple ports with same
311		 * address, just use the first one.
312		 */
313		if (fdb->is_local)
314			return 0;
315
316		printk(KERN_WARNING "%s adding interface with same address "
317		       "as a received packet\n",
318		       source->dev->name);
319		fdb_delete(fdb);
320 	}
321
322	if (!fdb_create(head, source, addr, 1))
323		return -ENOMEM;
324
325	return 0;
326}
327
328int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
329		  const unsigned char *addr)
330{
331	int ret;
332
333	spin_lock_bh(&br->hash_lock);
334	ret = fdb_insert(br, source, addr);
335	spin_unlock_bh(&br->hash_lock);
336	return ret;
337}
338
339void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
340		   const unsigned char *addr)
341{
342	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
343	struct net_bridge_fdb_entry *fdb;
344
345	/* some users want to always flood. */
346	if (hold_time(br) == 0)
347		return;
348
349	fdb = fdb_find(head, addr);
350	if (likely(fdb)) {
351		/* attempt to update an entry for a local interface */
352		if (unlikely(fdb->is_local)) {
353			if (net_ratelimit())
354				printk(KERN_WARNING "%s: received packet with "
355				       " own address as source address\n",
356				       source->dev->name);
357		} else {
358			/* fastpath: update of existing entry */
359			fdb->dst = source;
360			fdb->ageing_timer = jiffies;
361		}
362	} else {
363		spin_lock(&br->hash_lock);
364		if (!fdb_find(head, addr))
365			fdb_create(head, source, addr, 0);
366		/* else  we lose race and someone else inserts
367		 * it first, don't bother updating
368		 */
369		spin_unlock(&br->hash_lock);
370	}
371}
372