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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 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 */
13#include <linux/kernel.h>
Franck Bui-Huu82524742008-05-12 21:21:05 +020014#include <linux/rculist.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015
16#include "br_private.h"
17#include "br_private_stp.h"
18
19/* since time values in bpdu are in jiffies and then scaled (1/256)
20 * before sending, make sure that is at least one.
21 */
22#define MESSAGE_AGE_INCR ((HZ < 256) ? 1 : (HZ/256))
23
24static const char *br_port_state_names[] = {
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090025 [BR_STATE_DISABLED] = "disabled",
Linus Torvalds1da177e2005-04-16 15:20:36 -070026 [BR_STATE_LISTENING] = "listening",
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090027 [BR_STATE_LEARNING] = "learning",
28 [BR_STATE_FORWARDING] = "forwarding",
Linus Torvalds1da177e2005-04-16 15:20:36 -070029 [BR_STATE_BLOCKING] = "blocking",
30};
31
32void br_log_state(const struct net_bridge_port *p)
33{
34 pr_info("%s: port %d(%s) entering %s state\n",
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090035 p->br->dev->name, p->port_no, p->dev->name,
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 br_port_state_names[p->state]);
37
38}
39
40/* called under bridge lock */
41struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
42{
43 struct net_bridge_port *p;
44
45 list_for_each_entry_rcu(p, &br->port_list, list) {
46 if (p->port_no == port_no)
47 return p;
48 }
49
50 return NULL;
51}
52
53/* called under bridge lock */
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +090054static int br_should_become_root_port(const struct net_bridge_port *p,
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 u16 root_port)
56{
57 struct net_bridge *br;
58 struct net_bridge_port *rp;
59 int t;
60
61 br = p->br;
62 if (p->state == BR_STATE_DISABLED ||
63 br_is_designated_port(p))
64 return 0;
65
66 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
67 return 0;
68
69 if (!root_port)
70 return 1;
71
72 rp = br_get_port(br, root_port);
73
74 t = memcmp(&p->designated_root, &rp->designated_root, 8);
75 if (t < 0)
76 return 1;
77 else if (t > 0)
78 return 0;
79
80 if (p->designated_cost + p->path_cost <
81 rp->designated_cost + rp->path_cost)
82 return 1;
83 else if (p->designated_cost + p->path_cost >
84 rp->designated_cost + rp->path_cost)
85 return 0;
86
87 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
88 if (t < 0)
89 return 1;
90 else if (t > 0)
91 return 0;
92
93 if (p->designated_port < rp->designated_port)
94 return 1;
95 else if (p->designated_port > rp->designated_port)
96 return 0;
97
98 if (p->port_id < rp->port_id)
99 return 1;
100
101 return 0;
102}
103
104/* called under bridge lock */
105static void br_root_selection(struct net_bridge *br)
106{
107 struct net_bridge_port *p;
108 u16 root_port = 0;
109
110 list_for_each_entry(p, &br->port_list, list) {
111 if (br_should_become_root_port(p, root_port))
112 root_port = p->port_no;
113
114 }
115
116 br->root_port = root_port;
117
118 if (!root_port) {
119 br->designated_root = br->bridge_id;
120 br->root_path_cost = 0;
121 } else {
122 p = br_get_port(br, root_port);
123 br->designated_root = p->designated_root;
124 br->root_path_cost = p->designated_cost + p->path_cost;
125 }
126}
127
128/* called under bridge lock */
129void br_become_root_bridge(struct net_bridge *br)
130{
131 br->max_age = br->bridge_max_age;
132 br->hello_time = br->bridge_hello_time;
133 br->forward_delay = br->bridge_forward_delay;
134 br_topology_change_detection(br);
135 del_timer(&br->tcn_timer);
136
137 if (br->dev->flags & IFF_UP) {
138 br_config_bpdu_generation(br);
139 mod_timer(&br->hello_timer, jiffies + br->hello_time);
140 }
141}
142
143/* called under bridge lock */
144void br_transmit_config(struct net_bridge_port *p)
145{
146 struct br_config_bpdu bpdu;
147 struct net_bridge *br;
148
149
150 if (timer_pending(&p->hold_timer)) {
151 p->config_pending = 1;
152 return;
153 }
154
155 br = p->br;
156
157 bpdu.topology_change = br->topology_change;
158 bpdu.topology_change_ack = p->topology_change_ack;
159 bpdu.root = br->designated_root;
160 bpdu.root_path_cost = br->root_path_cost;
161 bpdu.bridge_id = br->bridge_id;
162 bpdu.port_id = p->port_id;
163 if (br_is_root_bridge(br))
164 bpdu.message_age = 0;
165 else {
166 struct net_bridge_port *root
167 = br_get_port(br, br->root_port);
168 bpdu.message_age = br->max_age
169 - (root->message_age_timer.expires - jiffies)
170 + MESSAGE_AGE_INCR;
171 }
172 bpdu.max_age = br->max_age;
173 bpdu.hello_time = br->hello_time;
174 bpdu.forward_delay = br->forward_delay;
175
176 if (bpdu.message_age < br->max_age) {
177 br_send_config_bpdu(p, &bpdu);
178 p->topology_change_ack = 0;
179 p->config_pending = 0;
Stephen Hemminger9a834b82007-05-31 01:21:39 -0700180 mod_timer(&p->hold_timer,
181 round_jiffies(jiffies + BR_HOLD_TIME));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 }
183}
184
185/* called under bridge lock */
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900186static inline void br_record_config_information(struct net_bridge_port *p,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 const struct br_config_bpdu *bpdu)
188{
189 p->designated_root = bpdu->root;
190 p->designated_cost = bpdu->root_path_cost;
191 p->designated_bridge = bpdu->bridge_id;
192 p->designated_port = bpdu->port_id;
193
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900194 mod_timer(&p->message_age_timer, jiffies
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 + (p->br->max_age - bpdu->message_age));
196}
197
198/* called under bridge lock */
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900199static inline void br_record_config_timeout_values(struct net_bridge *br,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 const struct br_config_bpdu *bpdu)
201{
202 br->max_age = bpdu->max_age;
203 br->hello_time = bpdu->hello_time;
204 br->forward_delay = bpdu->forward_delay;
205 br->topology_change = bpdu->topology_change;
206}
207
208/* called under bridge lock */
209void br_transmit_tcn(struct net_bridge *br)
210{
211 br_send_tcn_bpdu(br_get_port(br, br->root_port));
212}
213
214/* called under bridge lock */
215static int br_should_become_designated_port(const struct net_bridge_port *p)
216{
217 struct net_bridge *br;
218 int t;
219
220 br = p->br;
221 if (br_is_designated_port(p))
222 return 1;
223
224 if (memcmp(&p->designated_root, &br->designated_root, 8))
225 return 1;
226
227 if (br->root_path_cost < p->designated_cost)
228 return 1;
229 else if (br->root_path_cost > p->designated_cost)
230 return 0;
231
232 t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
233 if (t < 0)
234 return 1;
235 else if (t > 0)
236 return 0;
237
238 if (p->port_id < p->designated_port)
239 return 1;
240
241 return 0;
242}
243
244/* called under bridge lock */
245static void br_designated_port_selection(struct net_bridge *br)
246{
247 struct net_bridge_port *p;
248
249 list_for_each_entry(p, &br->port_list, list) {
250 if (p->state != BR_STATE_DISABLED &&
251 br_should_become_designated_port(p))
252 br_become_designated_port(p);
253
254 }
255}
256
257/* called under bridge lock */
258static int br_supersedes_port_info(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
259{
260 int t;
261
262 t = memcmp(&bpdu->root, &p->designated_root, 8);
263 if (t < 0)
264 return 1;
265 else if (t > 0)
266 return 0;
267
268 if (bpdu->root_path_cost < p->designated_cost)
269 return 1;
270 else if (bpdu->root_path_cost > p->designated_cost)
271 return 0;
272
273 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
274 if (t < 0)
275 return 1;
276 else if (t > 0)
277 return 0;
278
279 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
280 return 1;
281
282 if (bpdu->port_id <= p->designated_port)
283 return 1;
284
285 return 0;
286}
287
288/* called under bridge lock */
289static inline void br_topology_change_acknowledged(struct net_bridge *br)
290{
291 br->topology_change_detected = 0;
292 del_timer(&br->tcn_timer);
293}
294
295/* called under bridge lock */
296void br_topology_change_detection(struct net_bridge *br)
297{
298 int isroot = br_is_root_bridge(br);
299
300 pr_info("%s: topology change detected, %s\n", br->dev->name,
301 isroot ? "propagating" : "sending tcn bpdu");
302
303 if (isroot) {
304 br->topology_change = 1;
305 mod_timer(&br->topology_change_timer, jiffies
306 + br->bridge_forward_delay + br->bridge_max_age);
307 } else if (!br->topology_change_detected) {
308 br_transmit_tcn(br);
309 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
310 }
311
312 br->topology_change_detected = 1;
313}
314
315/* called under bridge lock */
316void br_config_bpdu_generation(struct net_bridge *br)
317{
318 struct net_bridge_port *p;
319
320 list_for_each_entry(p, &br->port_list, list) {
321 if (p->state != BR_STATE_DISABLED &&
322 br_is_designated_port(p))
323 br_transmit_config(p);
324 }
325}
326
327/* called under bridge lock */
328static inline void br_reply(struct net_bridge_port *p)
329{
330 br_transmit_config(p);
331}
332
333/* called under bridge lock */
334void br_configuration_update(struct net_bridge *br)
335{
336 br_root_selection(br);
337 br_designated_port_selection(br);
338}
339
340/* called under bridge lock */
341void br_become_designated_port(struct net_bridge_port *p)
342{
343 struct net_bridge *br;
344
345 br = p->br;
346 p->designated_root = br->designated_root;
347 p->designated_cost = br->root_path_cost;
348 p->designated_bridge = br->bridge_id;
349 p->designated_port = p->port_id;
350}
351
352
353/* called under bridge lock */
354static void br_make_blocking(struct net_bridge_port *p)
355{
356 if (p->state != BR_STATE_DISABLED &&
357 p->state != BR_STATE_BLOCKING) {
358 if (p->state == BR_STATE_FORWARDING ||
359 p->state == BR_STATE_LEARNING)
360 br_topology_change_detection(p->br);
361
362 p->state = BR_STATE_BLOCKING;
363 br_log_state(p);
364 del_timer(&p->forward_delay_timer);
365 }
366}
367
368/* called under bridge lock */
369static void br_make_forwarding(struct net_bridge_port *p)
370{
Stephen Hemmingeref647f12008-08-05 18:42:51 -0700371 struct net_bridge *br = p->br;
Stephen Hemminger9cde0702007-03-21 14:22:44 -0700372
Stephen Hemmingeref647f12008-08-05 18:42:51 -0700373 if (p->state != BR_STATE_BLOCKING)
374 return;
375
376 if (br->forward_delay == 0) {
377 p->state = BR_STATE_FORWARDING;
378 br_topology_change_detection(br);
379 del_timer(&p->forward_delay_timer);
380 }
381 else if (p->br->stp_enabled == BR_KERNEL_STP)
382 p->state = BR_STATE_LISTENING;
383 else
384 p->state = BR_STATE_LEARNING;
385
386 br_log_state(p);
387
388 if (br->forward_delay != 0)
389 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390}
391
392/* called under bridge lock */
393void br_port_state_selection(struct net_bridge *br)
394{
395 struct net_bridge_port *p;
396
Stephen Hemminger9cde0702007-03-21 14:22:44 -0700397 /* Don't change port states if userspace is handling STP */
398 if (br->stp_enabled == BR_USER_STP)
399 return;
400
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 list_for_each_entry(p, &br->port_list, list) {
402 if (p->state != BR_STATE_DISABLED) {
403 if (p->port_no == br->root_port) {
404 p->config_pending = 0;
405 p->topology_change_ack = 0;
406 br_make_forwarding(p);
407 } else if (br_is_designated_port(p)) {
408 del_timer(&p->message_age_timer);
409 br_make_forwarding(p);
410 } else {
411 p->config_pending = 0;
412 p->topology_change_ack = 0;
413 br_make_blocking(p);
414 }
415 }
416
417 }
418}
419
420/* called under bridge lock */
421static inline void br_topology_change_acknowledge(struct net_bridge_port *p)
422{
423 p->topology_change_ack = 1;
424 br_transmit_config(p);
425}
426
427/* called under bridge lock */
428void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
429{
430 struct net_bridge *br;
431 int was_root;
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900432
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 br = p->br;
434 was_root = br_is_root_bridge(br);
435
436 if (br_supersedes_port_info(p, bpdu)) {
437 br_record_config_information(p, bpdu);
438 br_configuration_update(br);
439 br_port_state_selection(br);
440
441 if (!br_is_root_bridge(br) && was_root) {
442 del_timer(&br->hello_timer);
443 if (br->topology_change_detected) {
444 del_timer(&br->topology_change_timer);
445 br_transmit_tcn(br);
446
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900447 mod_timer(&br->tcn_timer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 jiffies + br->bridge_hello_time);
449 }
450 }
451
452 if (p->port_no == br->root_port) {
453 br_record_config_timeout_values(br, bpdu);
454 br_config_bpdu_generation(br);
455 if (bpdu->topology_change_ack)
456 br_topology_change_acknowledged(br);
457 }
YOSHIFUJI Hideaki9d6f2292007-02-09 23:24:35 +0900458 } else if (br_is_designated_port(p)) {
459 br_reply(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 }
461}
462
463/* called under bridge lock */
464void br_received_tcn_bpdu(struct net_bridge_port *p)
465{
466 if (br_is_designated_port(p)) {
467 pr_info("%s: received tcn bpdu on port %i(%s)\n",
468 p->br->dev->name, p->port_no, p->dev->name);
469
470 br_topology_change_detection(p->br);
471 br_topology_change_acknowledge(p);
472 }
473}