1 /*
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
16 #include <linux/kernel.h>
17 #include <linux/if_bridge.h>
18 #include <linux/smp_lock.h>
19 #include <asm/uaccess.h>
20 #include "br_private.h"
21 #include "br_private_stp.h"
22
23
24
25 /* called under ioctl_lock or bridge lock */
26 int br_is_root_bridge(struct net_bridge *br)
27 {
28 return !memcmp(&br->bridge_id, &br->designated_root, 8);
29 }
30
31 /* called under bridge lock */
32 int br_is_designated_port(struct net_bridge_port *p)
33 {
34 return !memcmp(&p->designated_bridge, &p->br->bridge_id, 8) &&
35 (p->designated_port == p->port_id);
36 }
37
38 /* called under ioctl_lock or bridge lock */
39 struct net_bridge_port *br_get_port(struct net_bridge *br, int port_no)
40 {
41 struct net_bridge_port *p;
42
43 p = br->port_list;
44 while (p != NULL) {
45 if (p->port_no == port_no)
46 return p;
47
48 p = p->next;
49 }
50
51 return NULL;
52 }
53
54 /* called under bridge lock */
55 static int br_should_become_root_port(struct net_bridge_port *p, int 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 */
105 static void br_root_selection(struct net_bridge *br)
106 {
107 struct net_bridge_port *p;
108 int root_port;
109
110 root_port = 0;
111
112 p = br->port_list;
113 while (p != NULL) {
114 if (br_should_become_root_port(p, root_port))
115 root_port = p->port_no;
116
117 p = p->next;
118 }
119
120 br->root_port = root_port;
121
122 if (!root_port) {
123 br->designated_root = br->bridge_id;
124 br->root_path_cost = 0;
125 } else {
126 p = br_get_port(br, root_port);
127 br->designated_root = p->designated_root;
128 br->root_path_cost = p->designated_cost + p->path_cost;
129 }
130 }
131
132 /* called under bridge lock */
133 void br_become_root_bridge(struct net_bridge *br)
134 {
135 br->max_age = br->bridge_max_age;
136 br->hello_time = br->bridge_hello_time;
137 br->forward_delay = br->bridge_forward_delay;
138 br_topology_change_detection(br);
139 br_timer_clear(&br->tcn_timer);
140 br_config_bpdu_generation(br);
141 br_timer_set(&br->hello_timer, jiffies);
142 }
143
144 /* called under bridge lock */
145 void br_transmit_config(struct net_bridge_port *p)
146 {
147 struct br_config_bpdu bpdu;
148 struct net_bridge *br;
149
150 if (br_timer_is_running(&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 bpdu.message_age = 0;
164 if (!br_is_root_bridge(br)) {
165 struct net_bridge_port *root;
166 unsigned long age;
167
168 root = br_get_port(br, br->root_port);
169 age = br_timer_get_residue(&root->message_age_timer) + 1;
170 bpdu.message_age = age;
171 }
172 bpdu.max_age = br->max_age;
173 bpdu.hello_time = br->hello_time;
174 bpdu.forward_delay = br->forward_delay;
175
176 br_send_config_bpdu(p, &bpdu);
177
178 p->topology_change_ack = 0;
179 p->config_pending = 0;
180 br_timer_set(&p->hold_timer, jiffies);
181 }
182
183 /* called under bridge lock */
184 static void br_record_config_information(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
185 {
186 p->designated_root = bpdu->root;
187 p->designated_cost = bpdu->root_path_cost;
188 p->designated_bridge = bpdu->bridge_id;
189 p->designated_port = bpdu->port_id;
190
191 br_timer_set(&p->message_age_timer, jiffies - bpdu->message_age);
192 }
193
194 /* called under bridge lock */
195 static void br_record_config_timeout_values(struct net_bridge *br, struct br_config_bpdu *bpdu)
196 {
197 br->max_age = bpdu->max_age;
198 br->hello_time = bpdu->hello_time;
199 br->forward_delay = bpdu->forward_delay;
200 br->topology_change = bpdu->topology_change;
201 }
202
203 /* called under bridge lock */
204 void br_transmit_tcn(struct net_bridge *br)
205 {
206 br_send_tcn_bpdu(br_get_port(br, br->root_port));
207 }
208
209 /* called under bridge lock */
210 static int br_should_become_designated_port(struct net_bridge_port *p)
211 {
212 struct net_bridge *br;
213 int t;
214
215 br = p->br;
216 if (br_is_designated_port(p))
217 return 1;
218
219 if (memcmp(&p->designated_root, &br->designated_root, 8))
220 return 1;
221
222 if (br->root_path_cost < p->designated_cost)
223 return 1;
224 else if (br->root_path_cost > p->designated_cost)
225 return 0;
226
227 t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
228 if (t < 0)
229 return 1;
230 else if (t > 0)
231 return 0;
232
233 if (p->port_id < p->designated_port)
234 return 1;
235
236 return 0;
237 }
238
239 /* called under bridge lock */
240 static void br_designated_port_selection(struct net_bridge *br)
241 {
242 struct net_bridge_port *p;
243
244 p = br->port_list;
245 while (p != NULL) {
246 if (p->state != BR_STATE_DISABLED &&
247 br_should_become_designated_port(p))
248 br_become_designated_port(p);
249
250 p = p->next;
251 }
252 }
253
254 /* called under bridge lock */
255 static int br_supersedes_port_info(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
256 {
257 int t;
258
259 t = memcmp(&bpdu->root, &p->designated_root, 8);
260 if (t < 0)
261 return 1;
262 else if (t > 0)
263 return 0;
264
265 if (bpdu->root_path_cost < p->designated_cost)
266 return 1;
267 else if (bpdu->root_path_cost > p->designated_cost)
268 return 0;
269
270 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
271 if (t < 0)
272 return 1;
273 else if (t > 0)
274 return 0;
275
276 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
277 return 1;
278
279 if (bpdu->port_id <= p->designated_port)
280 return 1;
281
282 return 0;
283 }
284
285 /* called under bridge lock */
286 static void br_topology_change_acknowledged(struct net_bridge *br)
287 {
288 br->topology_change_detected = 0;
289 br_timer_clear(&br->tcn_timer);
290 }
291
292 /* called under bridge lock */
293 void br_topology_change_detection(struct net_bridge *br)
294 {
295 printk(KERN_INFO "%s: topology change detected", br->dev.name);
296
297 if (br_is_root_bridge(br)) {
298 printk(", propagating");
299 br->topology_change = 1;
300 br_timer_set(&br->topology_change_timer, jiffies);
301 } else if (!br->topology_change_detected) {
302 printk(", sending tcn bpdu");
303 br_transmit_tcn(br);
304 br_timer_set(&br->tcn_timer, jiffies);
305 }
306
307 printk("\n");
308 br->topology_change_detected = 1;
309 }
310
311 /* called under bridge lock */
312 void br_config_bpdu_generation(struct net_bridge *br)
313 {
314 struct net_bridge_port *p;
315
316 p = br->port_list;
317 while (p != NULL) {
318 if (p->state != BR_STATE_DISABLED &&
319 br_is_designated_port(p))
320 br_transmit_config(p);
321
322 p = p->next;
323 }
324 }
325
326 /* called under bridge lock */
327 static void br_reply(struct net_bridge_port *p)
328 {
329 br_transmit_config(p);
330 }
331
332 /* called under bridge lock */
333 void br_configuration_update(struct net_bridge *br)
334 {
335 br_root_selection(br);
336 br_designated_port_selection(br);
337 }
338
339 /* called under bridge lock */
340 void br_become_designated_port(struct net_bridge_port *p)
341 {
342 struct net_bridge *br;
343
344 br = p->br;
345 p->designated_root = br->designated_root;
346 p->designated_cost = br->root_path_cost;
347 p->designated_bridge = br->bridge_id;
348 p->designated_port = p->port_id;
349 }
350
351 /* called under bridge lock */
352 static void br_make_blocking(struct net_bridge_port *p)
353 {
354 if (p->state != BR_STATE_DISABLED &&
355 p->state != BR_STATE_BLOCKING) {
356 if (p->state == BR_STATE_FORWARDING ||
357 p->state == BR_STATE_LEARNING)
358 br_topology_change_detection(p->br);
359
360 printk(KERN_INFO "%s: port %i(%s) entering %s state\n",
361 p->br->dev.name, p->port_no, p->dev->name, "blocking");
362
363 p->state = BR_STATE_BLOCKING;
364 br_timer_clear(&p->forward_delay_timer);
365 }
366 }
367
368 /* called under bridge lock */
369 static void br_make_forwarding(struct net_bridge_port *p)
370 {
371 if (p->state == BR_STATE_BLOCKING) {
372 printk(KERN_INFO "%s: port %i(%s) entering %s state\n",
373 p->br->dev.name, p->port_no, p->dev->name, "listening");
374
375 p->state = BR_STATE_LISTENING;
376 br_timer_set(&p->forward_delay_timer, jiffies);
377 }
378 }
379
380 /* called under bridge lock */
381 void br_port_state_selection(struct net_bridge *br)
382 {
383 struct net_bridge_port *p;
384
385 p = br->port_list;
386 while (p != NULL) {
387 if (p->state != BR_STATE_DISABLED) {
388 if (p->port_no == br->root_port) {
389 p->config_pending = 0;
390 p->topology_change_ack = 0;
391 br_make_forwarding(p);
392 } else if (br_is_designated_port(p)) {
393 br_timer_clear(&p->message_age_timer);
394 br_make_forwarding(p);
395 } else {
396 p->config_pending = 0;
397 p->topology_change_ack = 0;
398 br_make_blocking(p);
399 }
400 }
401
402 p = p->next;
403 }
404 }
405
406 /* called under bridge lock */
407 static 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 /* lock-safe */
414 void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
415 {
416 struct net_bridge *br;
417 int was_root;
418
419 if (p->state == BR_STATE_DISABLED)
420 return;
421
422 br = p->br;
423 read_lock(&br->lock);
424
425 was_root = br_is_root_bridge(br);
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 br_timer_clear(&br->hello_timer);
433 if (br->topology_change_detected) {
434 br_timer_clear(&br->topology_change_timer);
435 br_transmit_tcn(br);
436 br_timer_set(&br->tcn_timer, jiffies);
437 }
438 }
439
440 if (p->port_no == br->root_port) {
441 br_record_config_timeout_values(br, bpdu);
442 br_config_bpdu_generation(br);
443 if (bpdu->topology_change_ack)
444 br_topology_change_acknowledged(br);
445 }
446 } else if (br_is_designated_port(p)) {
447 br_reply(p);
448 }
449
450 read_unlock(&br->lock);
451 }
452
453 /* lock-safe */
454 void br_received_tcn_bpdu(struct net_bridge_port *p)
455 {
456 read_lock(&p->br->lock);
457 if (p->state != BR_STATE_DISABLED &&
458 br_is_designated_port(p)) {
459 printk(KERN_INFO "%s: received tcn bpdu on port %i(%s)\n",
460 p->br->dev.name, p->port_no, p->dev->name);
461
462 br_topology_change_detection(p->br);
463 br_topology_change_acknowledge(p);
464 }
465 read_unlock(&p->br->lock);
466 }
467
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