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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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016
17#include "br_private.h"
18#include "br_private_stp.h"
19
20/* since time values in bpdu are in jiffies and then scaled (1/256)
21 * before sending, make sure that is at least one.
22 */
23#define MESSAGE_AGE_INCR ((HZ < 256) ? 1 : (HZ/256))
24
25static const char *br_port_state_names[] = {
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090026 [BR_STATE_DISABLED] = "disabled",
Linus Torvalds1da177e2005-04-16 15:20:36 -070027 [BR_STATE_LISTENING] = "listening",
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090028 [BR_STATE_LEARNING] = "learning",
29 [BR_STATE_FORWARDING] = "forwarding",
Linus Torvalds1da177e2005-04-16 15:20:36 -070030 [BR_STATE_BLOCKING] = "blocking",
31};
32
33void br_log_state(const struct net_bridge_port *p)
34{
35 pr_info("%s: port %d(%s) entering %s state\n",
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090036 p->br->dev->name, p->port_no, p->dev->name,
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 br_port_state_names[p->state]);
38
39}
40
41/* called under bridge lock */
42struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
43{
44 struct net_bridge_port *p;
45
46 list_for_each_entry_rcu(p, &br->port_list, list) {
47 if (p->port_no == port_no)
48 return p;
49 }
50
51 return NULL;
52}
53
54/* called under bridge lock */
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090055static int br_should_become_root_port(const struct net_bridge_port *p,
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 u16 root_port)
57{
58 struct net_bridge *br;
59 struct net_bridge_port *rp;
60 int t;
61
62 br = p->br;
63 if (p->state == BR_STATE_DISABLED ||
64 br_is_designated_port(p))
65 return 0;
66
67 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
68 return 0;
69
70 if (!root_port)
71 return 1;
72
73 rp = br_get_port(br, root_port);
74
75 t = memcmp(&p->designated_root, &rp->designated_root, 8);
76 if (t < 0)
77 return 1;
78 else if (t > 0)
79 return 0;
80
81 if (p->designated_cost + p->path_cost <
82 rp->designated_cost + rp->path_cost)
83 return 1;
84 else if (p->designated_cost + p->path_cost >
85 rp->designated_cost + rp->path_cost)
86 return 0;
87
88 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
89 if (t < 0)
90 return 1;
91 else if (t > 0)
92 return 0;
93
94 if (p->designated_port < rp->designated_port)
95 return 1;
96 else if (p->designated_port > rp->designated_port)
97 return 0;
98
99 if (p->port_id < rp->port_id)
100 return 1;
101
102 return 0;
103}
104
105/* called under bridge lock */
106static void br_root_selection(struct net_bridge *br)
107{
108 struct net_bridge_port *p;
109 u16 root_port = 0;
110
111 list_for_each_entry(p, &br->port_list, list) {
112 if (br_should_become_root_port(p, root_port))
113 root_port = p->port_no;
114
115 }
116
117 br->root_port = root_port;
118
119 if (!root_port) {
120 br->designated_root = br->bridge_id;
121 br->root_path_cost = 0;
122 } else {
123 p = br_get_port(br, root_port);
124 br->designated_root = p->designated_root;
125 br->root_path_cost = p->designated_cost + p->path_cost;
126 }
127}
128
129/* called under bridge lock */
130void br_become_root_bridge(struct net_bridge *br)
131{
132 br->max_age = br->bridge_max_age;
133 br->hello_time = br->bridge_hello_time;
134 br->forward_delay = br->bridge_forward_delay;
135 br_topology_change_detection(br);
136 del_timer(&br->tcn_timer);
137
138 if (br->dev->flags & IFF_UP) {
139 br_config_bpdu_generation(br);
140 mod_timer(&br->hello_timer, jiffies + br->hello_time);
141 }
142}
143
144/* called under bridge lock */
145void br_transmit_config(struct net_bridge_port *p)
146{
147 struct br_config_bpdu bpdu;
148 struct net_bridge *br;
149
150
151 if (timer_pending(&p->hold_timer)) {
152 p->config_pending = 1;
153 return;
154 }
155
156 br = p->br;
157
158 bpdu.topology_change = br->topology_change;
159 bpdu.topology_change_ack = p->topology_change_ack;
160 bpdu.root = br->designated_root;
161 bpdu.root_path_cost = br->root_path_cost;
162 bpdu.bridge_id = br->bridge_id;
163 bpdu.port_id = p->port_id;
164 if (br_is_root_bridge(br))
165 bpdu.message_age = 0;
166 else {
167 struct net_bridge_port *root
168 = br_get_port(br, br->root_port);
169 bpdu.message_age = br->max_age
170 - (root->message_age_timer.expires - jiffies)
171 + MESSAGE_AGE_INCR;
172 }
173 bpdu.max_age = br->max_age;
174 bpdu.hello_time = br->hello_time;
175 bpdu.forward_delay = br->forward_delay;
176
177 if (bpdu.message_age < br->max_age) {
178 br_send_config_bpdu(p, &bpdu);
179 p->topology_change_ack = 0;
180 p->config_pending = 0;
Stephen Hemminger9a834b82007-05-31 01:21:39 -0700181 mod_timer(&p->hold_timer,
182 round_jiffies(jiffies + BR_HOLD_TIME));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 }
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) {
Stephen Hemminger9cde0702007-03-21 14:22:44 -0700373 if (p->br->stp_enabled == BR_KERNEL_STP)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 p->state = BR_STATE_LISTENING;
Stephen Hemminger9cde0702007-03-21 14:22:44 -0700375 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 p->state = BR_STATE_LEARNING;
Stephen Hemminger9cde0702007-03-21 14:22:44 -0700377
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 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
Stephen Hemminger9cde0702007-03-21 14:22:44 -0700387 /* Don't change port states if userspace is handling STP */
388 if (br->stp_enabled == BR_USER_STP)
389 return;
390
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 list_for_each_entry(p, &br->port_list, list) {
392 if (p->state != BR_STATE_DISABLED) {
393 if (p->port_no == br->root_port) {
394 p->config_pending = 0;
395 p->topology_change_ack = 0;
396 br_make_forwarding(p);
397 } else if (br_is_designated_port(p)) {
398 del_timer(&p->message_age_timer);
399 br_make_forwarding(p);
400 } else {
401 p->config_pending = 0;
402 p->topology_change_ack = 0;
403 br_make_blocking(p);
404 }
405 }
406
407 }
408}
409
410/* called under bridge lock */
411static inline void br_topology_change_acknowledge(struct net_bridge_port *p)
412{
413 p->topology_change_ack = 1;
414 br_transmit_config(p);
415}
416
417/* called under bridge lock */
418void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
419{
420 struct net_bridge *br;
421 int was_root;
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900422
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 br = p->br;
424 was_root = br_is_root_bridge(br);
425
426 if (br_supersedes_port_info(p, bpdu)) {
427 br_record_config_information(p, bpdu);
428 br_configuration_update(br);
429 br_port_state_selection(br);
430
431 if (!br_is_root_bridge(br) && was_root) {
432 del_timer(&br->hello_timer);
433 if (br->topology_change_detected) {
434 del_timer(&br->topology_change_timer);
435 br_transmit_tcn(br);
436
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900437 mod_timer(&br->tcn_timer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 jiffies + br->bridge_hello_time);
439 }
440 }
441
442 if (p->port_no == br->root_port) {
443 br_record_config_timeout_values(br, bpdu);
444 br_config_bpdu_generation(br);
445 if (bpdu->topology_change_ack)
446 br_topology_change_acknowledged(br);
447 }
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900448 } else if (br_is_designated_port(p)) {
449 br_reply(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 }
451}
452
453/* called under bridge lock */
454void br_received_tcn_bpdu(struct net_bridge_port *p)
455{
456 if (br_is_designated_port(p)) {
457 pr_info("%s: received tcn bpdu on port %i(%s)\n",
458 p->br->dev->name, p->port_no, p->dev->name);
459
460 br_topology_change_detection(p->br);
461 br_topology_change_acknowledge(p);
462 }
463}