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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Spanning tree protocol; generic parts
3 * Linux ethernet bridge
4 *
5 * Authors:
6 * Lennert Buytenhek <buytenh@gnu.org>
7 *
8 * $Id: br_stp.c,v 1.4 2000/06/19 10:13:35 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#include <linux/kernel.h>
16#include <linux/smp_lock.h>
17
18#include "br_private.h"
19#include "br_private_stp.h"
20
21/* since time values in bpdu are in jiffies and then scaled (1/256)
22 * before sending, make sure that is at least one.
23 */
24#define MESSAGE_AGE_INCR ((HZ < 256) ? 1 : (HZ/256))
25
26static const char *br_port_state_names[] = {
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090027 [BR_STATE_DISABLED] = "disabled",
Linus Torvalds1da177e2005-04-16 15:20:36 -070028 [BR_STATE_LISTENING] = "listening",
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090029 [BR_STATE_LEARNING] = "learning",
30 [BR_STATE_FORWARDING] = "forwarding",
Linus Torvalds1da177e2005-04-16 15:20:36 -070031 [BR_STATE_BLOCKING] = "blocking",
32};
33
34void br_log_state(const struct net_bridge_port *p)
35{
36 pr_info("%s: port %d(%s) entering %s state\n",
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090037 p->br->dev->name, p->port_no, p->dev->name,
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 br_port_state_names[p->state]);
39
40}
41
42/* called under bridge lock */
43struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
44{
45 struct net_bridge_port *p;
46
47 list_for_each_entry_rcu(p, &br->port_list, list) {
48 if (p->port_no == port_no)
49 return p;
50 }
51
52 return NULL;
53}
54
55/* called under bridge lock */
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090056static int br_should_become_root_port(const struct net_bridge_port *p,
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 u16 root_port)
58{
59 struct net_bridge *br;
60 struct net_bridge_port *rp;
61 int t;
62
63 br = p->br;
64 if (p->state == BR_STATE_DISABLED ||
65 br_is_designated_port(p))
66 return 0;
67
68 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
69 return 0;
70
71 if (!root_port)
72 return 1;
73
74 rp = br_get_port(br, root_port);
75
76 t = memcmp(&p->designated_root, &rp->designated_root, 8);
77 if (t < 0)
78 return 1;
79 else if (t > 0)
80 return 0;
81
82 if (p->designated_cost + p->path_cost <
83 rp->designated_cost + rp->path_cost)
84 return 1;
85 else if (p->designated_cost + p->path_cost >
86 rp->designated_cost + rp->path_cost)
87 return 0;
88
89 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
90 if (t < 0)
91 return 1;
92 else if (t > 0)
93 return 0;
94
95 if (p->designated_port < rp->designated_port)
96 return 1;
97 else if (p->designated_port > rp->designated_port)
98 return 0;
99
100 if (p->port_id < rp->port_id)
101 return 1;
102
103 return 0;
104}
105
106/* called under bridge lock */
107static void br_root_selection(struct net_bridge *br)
108{
109 struct net_bridge_port *p;
110 u16 root_port = 0;
111
112 list_for_each_entry(p, &br->port_list, list) {
113 if (br_should_become_root_port(p, root_port))
114 root_port = p->port_no;
115
116 }
117
118 br->root_port = root_port;
119
120 if (!root_port) {
121 br->designated_root = br->bridge_id;
122 br->root_path_cost = 0;
123 } else {
124 p = br_get_port(br, root_port);
125 br->designated_root = p->designated_root;
126 br->root_path_cost = p->designated_cost + p->path_cost;
127 }
128}
129
130/* called under bridge lock */
131void br_become_root_bridge(struct net_bridge *br)
132{
133 br->max_age = br->bridge_max_age;
134 br->hello_time = br->bridge_hello_time;
135 br->forward_delay = br->bridge_forward_delay;
136 br_topology_change_detection(br);
137 del_timer(&br->tcn_timer);
138
139 if (br->dev->flags & IFF_UP) {
140 br_config_bpdu_generation(br);
141 mod_timer(&br->hello_timer, jiffies + br->hello_time);
142 }
143}
144
145/* called under bridge lock */
146void br_transmit_config(struct net_bridge_port *p)
147{
148 struct br_config_bpdu bpdu;
149 struct net_bridge *br;
150
151
152 if (timer_pending(&p->hold_timer)) {
153 p->config_pending = 1;
154 return;
155 }
156
157 br = p->br;
158
159 bpdu.topology_change = br->topology_change;
160 bpdu.topology_change_ack = p->topology_change_ack;
161 bpdu.root = br->designated_root;
162 bpdu.root_path_cost = br->root_path_cost;
163 bpdu.bridge_id = br->bridge_id;
164 bpdu.port_id = p->port_id;
165 if (br_is_root_bridge(br))
166 bpdu.message_age = 0;
167 else {
168 struct net_bridge_port *root
169 = br_get_port(br, br->root_port);
170 bpdu.message_age = br->max_age
171 - (root->message_age_timer.expires - jiffies)
172 + MESSAGE_AGE_INCR;
173 }
174 bpdu.max_age = br->max_age;
175 bpdu.hello_time = br->hello_time;
176 bpdu.forward_delay = br->forward_delay;
177
178 if (bpdu.message_age < br->max_age) {
179 br_send_config_bpdu(p, &bpdu);
180 p->topology_change_ack = 0;
181 p->config_pending = 0;
182 mod_timer(&p->hold_timer, jiffies + BR_HOLD_TIME);
183 }
184}
185
186/* called under bridge lock */
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900187static inline void br_record_config_information(struct net_bridge_port *p,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 const struct br_config_bpdu *bpdu)
189{
190 p->designated_root = bpdu->root;
191 p->designated_cost = bpdu->root_path_cost;
192 p->designated_bridge = bpdu->bridge_id;
193 p->designated_port = bpdu->port_id;
194
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900195 mod_timer(&p->message_age_timer, jiffies
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 + (p->br->max_age - bpdu->message_age));
197}
198
199/* called under bridge lock */
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900200static inline void br_record_config_timeout_values(struct net_bridge *br,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 const struct br_config_bpdu *bpdu)
202{
203 br->max_age = bpdu->max_age;
204 br->hello_time = bpdu->hello_time;
205 br->forward_delay = bpdu->forward_delay;
206 br->topology_change = bpdu->topology_change;
207}
208
209/* called under bridge lock */
210void br_transmit_tcn(struct net_bridge *br)
211{
212 br_send_tcn_bpdu(br_get_port(br, br->root_port));
213}
214
215/* called under bridge lock */
216static int br_should_become_designated_port(const struct net_bridge_port *p)
217{
218 struct net_bridge *br;
219 int t;
220
221 br = p->br;
222 if (br_is_designated_port(p))
223 return 1;
224
225 if (memcmp(&p->designated_root, &br->designated_root, 8))
226 return 1;
227
228 if (br->root_path_cost < p->designated_cost)
229 return 1;
230 else if (br->root_path_cost > p->designated_cost)
231 return 0;
232
233 t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
234 if (t < 0)
235 return 1;
236 else if (t > 0)
237 return 0;
238
239 if (p->port_id < p->designated_port)
240 return 1;
241
242 return 0;
243}
244
245/* called under bridge lock */
246static void br_designated_port_selection(struct net_bridge *br)
247{
248 struct net_bridge_port *p;
249
250 list_for_each_entry(p, &br->port_list, list) {
251 if (p->state != BR_STATE_DISABLED &&
252 br_should_become_designated_port(p))
253 br_become_designated_port(p);
254
255 }
256}
257
258/* called under bridge lock */
259static int br_supersedes_port_info(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
260{
261 int t;
262
263 t = memcmp(&bpdu->root, &p->designated_root, 8);
264 if (t < 0)
265 return 1;
266 else if (t > 0)
267 return 0;
268
269 if (bpdu->root_path_cost < p->designated_cost)
270 return 1;
271 else if (bpdu->root_path_cost > p->designated_cost)
272 return 0;
273
274 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
275 if (t < 0)
276 return 1;
277 else if (t > 0)
278 return 0;
279
280 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
281 return 1;
282
283 if (bpdu->port_id <= p->designated_port)
284 return 1;
285
286 return 0;
287}
288
289/* called under bridge lock */
290static inline void br_topology_change_acknowledged(struct net_bridge *br)
291{
292 br->topology_change_detected = 0;
293 del_timer(&br->tcn_timer);
294}
295
296/* called under bridge lock */
297void br_topology_change_detection(struct net_bridge *br)
298{
299 int isroot = br_is_root_bridge(br);
300
301 pr_info("%s: topology change detected, %s\n", br->dev->name,
302 isroot ? "propagating" : "sending tcn bpdu");
303
304 if (isroot) {
305 br->topology_change = 1;
306 mod_timer(&br->topology_change_timer, jiffies
307 + br->bridge_forward_delay + br->bridge_max_age);
308 } else if (!br->topology_change_detected) {
309 br_transmit_tcn(br);
310 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
311 }
312
313 br->topology_change_detected = 1;
314}
315
316/* called under bridge lock */
317void br_config_bpdu_generation(struct net_bridge *br)
318{
319 struct net_bridge_port *p;
320
321 list_for_each_entry(p, &br->port_list, list) {
322 if (p->state != BR_STATE_DISABLED &&
323 br_is_designated_port(p))
324 br_transmit_config(p);
325 }
326}
327
328/* called under bridge lock */
329static inline void br_reply(struct net_bridge_port *p)
330{
331 br_transmit_config(p);
332}
333
334/* called under bridge lock */
335void br_configuration_update(struct net_bridge *br)
336{
337 br_root_selection(br);
338 br_designated_port_selection(br);
339}
340
341/* called under bridge lock */
342void br_become_designated_port(struct net_bridge_port *p)
343{
344 struct net_bridge *br;
345
346 br = p->br;
347 p->designated_root = br->designated_root;
348 p->designated_cost = br->root_path_cost;
349 p->designated_bridge = br->bridge_id;
350 p->designated_port = p->port_id;
351}
352
353
354/* called under bridge lock */
355static void br_make_blocking(struct net_bridge_port *p)
356{
357 if (p->state != BR_STATE_DISABLED &&
358 p->state != BR_STATE_BLOCKING) {
359 if (p->state == BR_STATE_FORWARDING ||
360 p->state == BR_STATE_LEARNING)
361 br_topology_change_detection(p->br);
362
363 p->state = BR_STATE_BLOCKING;
364 br_log_state(p);
365 del_timer(&p->forward_delay_timer);
366 }
367}
368
369/* called under bridge lock */
370static void br_make_forwarding(struct net_bridge_port *p)
371{
372 if (p->state == BR_STATE_BLOCKING) {
373 if (p->br->stp_enabled) {
374 p->state = BR_STATE_LISTENING;
375 } else {
376 p->state = BR_STATE_LEARNING;
377 }
378 br_log_state(p);
379 mod_timer(&p->forward_delay_timer, jiffies + p->br->forward_delay); }
380}
381
382/* called under bridge lock */
383void br_port_state_selection(struct net_bridge *br)
384{
385 struct net_bridge_port *p;
386
387 list_for_each_entry(p, &br->port_list, list) {
388 if (p->state != BR_STATE_DISABLED) {
389 if (p->port_no == br->root_port) {
390 p->config_pending = 0;
391 p->topology_change_ack = 0;
392 br_make_forwarding(p);
393 } else if (br_is_designated_port(p)) {
394 del_timer(&p->message_age_timer);
395 br_make_forwarding(p);
396 } else {
397 p->config_pending = 0;
398 p->topology_change_ack = 0;
399 br_make_blocking(p);
400 }
401 }
402
403 }
404}
405
406/* called under bridge lock */
407static inline void br_topology_change_acknowledge(struct net_bridge_port *p)
408{
409 p->topology_change_ack = 1;
410 br_transmit_config(p);
411}
412
413/* called under bridge lock */
414void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
415{
416 struct net_bridge *br;
417 int was_root;
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900418
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 br = p->br;
420 was_root = br_is_root_bridge(br);
421
422 if (br_supersedes_port_info(p, bpdu)) {
423 br_record_config_information(p, bpdu);
424 br_configuration_update(br);
425 br_port_state_selection(br);
426
427 if (!br_is_root_bridge(br) && was_root) {
428 del_timer(&br->hello_timer);
429 if (br->topology_change_detected) {
430 del_timer(&br->topology_change_timer);
431 br_transmit_tcn(br);
432
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900433 mod_timer(&br->tcn_timer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 jiffies + br->bridge_hello_time);
435 }
436 }
437
438 if (p->port_no == br->root_port) {
439 br_record_config_timeout_values(br, bpdu);
440 br_config_bpdu_generation(br);
441 if (bpdu->topology_change_ack)
442 br_topology_change_acknowledged(br);
443 }
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900444 } else if (br_is_designated_port(p)) {
445 br_reply(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446 }
447}
448
449/* called under bridge lock */
450void br_received_tcn_bpdu(struct net_bridge_port *p)
451{
452 if (br_is_designated_port(p)) {
453 pr_info("%s: received tcn bpdu on port %i(%s)\n",
454 p->br->dev->name, p->port_no, p->dev->name);
455
456 br_topology_change_detection(p->br);
457 br_topology_change_acknowledge(p);
458 }
459}