2 * Spanning tree protocol; generic parts
3 * Linux ethernet bridge
6 * Lennert Buytenhek <buytenh@gnu.org>
8 * $Id: br_stp.c,v 1.4 2000/06/19 10:13:35 davem Exp $
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.
15 #include <linux/kernel.h>
17 #include "br_private.h"
18 #include "br_private_stp.h"
20 /* since time values in bpdu are in jiffies and then scaled (1/256)
21 * before sending, make sure that is at least one.
23 #define MESSAGE_AGE_INCR ((HZ < 256) ? 1 : (HZ/256))
25 static const char *br_port_state_names[] = {
26 [BR_STATE_DISABLED] = "disabled",
27 [BR_STATE_LISTENING] = "listening",
28 [BR_STATE_LEARNING] = "learning",
29 [BR_STATE_FORWARDING] = "forwarding",
30 [BR_STATE_BLOCKING] = "blocking",
33 void br_log_state(const struct net_bridge_port *p)
35 pr_info("%s: port %d(%s) entering %s state\n",
36 p->br->dev->name, p->port_no, p->dev->name,
37 br_port_state_names[p->state]);
41 /* called under bridge lock */
42 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
44 struct net_bridge_port *p;
46 list_for_each_entry_rcu(p, &br->port_list, list) {
47 if (p->port_no == port_no)
54 /* called under bridge lock */
55 static int br_should_become_root_port(const struct net_bridge_port *p,
58 struct net_bridge *br;
59 struct net_bridge_port *rp;
63 if (p->state == BR_STATE_DISABLED ||
64 br_is_designated_port(p))
67 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
73 rp = br_get_port(br, root_port);
75 t = memcmp(&p->designated_root, &rp->designated_root, 8);
81 if (p->designated_cost + p->path_cost <
82 rp->designated_cost + rp->path_cost)
84 else if (p->designated_cost + p->path_cost >
85 rp->designated_cost + rp->path_cost)
88 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
94 if (p->designated_port < rp->designated_port)
96 else if (p->designated_port > rp->designated_port)
99 if (p->port_id < rp->port_id)
105 /* called under bridge lock */
106 static void br_root_selection(struct net_bridge *br)
108 struct net_bridge_port *p;
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;
117 br->root_port = root_port;
120 br->designated_root = br->bridge_id;
121 br->root_path_cost = 0;
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;
129 /* called under bridge lock */
130 void br_become_root_bridge(struct net_bridge *br)
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);
138 if (br->dev->flags & IFF_UP) {
139 br_config_bpdu_generation(br);
140 mod_timer(&br->hello_timer, jiffies + br->hello_time);
144 /* called under bridge lock */
145 void br_transmit_config(struct net_bridge_port *p)
147 struct br_config_bpdu bpdu;
148 struct net_bridge *br;
151 if (timer_pending(&p->hold_timer)) {
152 p->config_pending = 1;
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;
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)
173 bpdu.max_age = br->max_age;
174 bpdu.hello_time = br->hello_time;
175 bpdu.forward_delay = br->forward_delay;
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;
181 mod_timer(&p->hold_timer, jiffies + BR_HOLD_TIME);
185 /* called under bridge lock */
186 static inline void br_record_config_information(struct net_bridge_port *p,
187 const struct br_config_bpdu *bpdu)
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;
194 mod_timer(&p->message_age_timer, jiffies
195 + (p->br->max_age - bpdu->message_age));
198 /* called under bridge lock */
199 static inline void br_record_config_timeout_values(struct net_bridge *br,
200 const struct br_config_bpdu *bpdu)
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;
208 /* called under bridge lock */
209 void br_transmit_tcn(struct net_bridge *br)
211 br_send_tcn_bpdu(br_get_port(br, br->root_port));
214 /* called under bridge lock */
215 static int br_should_become_designated_port(const struct net_bridge_port *p)
217 struct net_bridge *br;
221 if (br_is_designated_port(p))
224 if (memcmp(&p->designated_root, &br->designated_root, 8))
227 if (br->root_path_cost < p->designated_cost)
229 else if (br->root_path_cost > p->designated_cost)
232 t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
238 if (p->port_id < p->designated_port)
244 /* called under bridge lock */
245 static void br_designated_port_selection(struct net_bridge *br)
247 struct net_bridge_port *p;
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);
257 /* called under bridge lock */
258 static int br_supersedes_port_info(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
262 t = memcmp(&bpdu->root, &p->designated_root, 8);
268 if (bpdu->root_path_cost < p->designated_cost)
270 else if (bpdu->root_path_cost > p->designated_cost)
273 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
279 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
282 if (bpdu->port_id <= p->designated_port)
288 /* called under bridge lock */
289 static inline void br_topology_change_acknowledged(struct net_bridge *br)
291 br->topology_change_detected = 0;
292 del_timer(&br->tcn_timer);
295 /* called under bridge lock */
296 void br_topology_change_detection(struct net_bridge *br)
298 int isroot = br_is_root_bridge(br);
300 pr_info("%s: topology change detected, %s\n", br->dev->name,
301 isroot ? "propagating" : "sending tcn bpdu");
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) {
309 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
312 br->topology_change_detected = 1;
315 /* called under bridge lock */
316 void br_config_bpdu_generation(struct net_bridge *br)
318 struct net_bridge_port *p;
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);
327 /* called under bridge lock */
328 static inline void br_reply(struct net_bridge_port *p)
330 br_transmit_config(p);
333 /* called under bridge lock */
334 void br_configuration_update(struct net_bridge *br)
336 br_root_selection(br);
337 br_designated_port_selection(br);
340 /* called under bridge lock */
341 void br_become_designated_port(struct net_bridge_port *p)
343 struct net_bridge *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;
353 /* called under bridge lock */
354 static void br_make_blocking(struct net_bridge_port *p)
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);
362 p->state = BR_STATE_BLOCKING;
364 del_timer(&p->forward_delay_timer);
368 /* called under bridge lock */
369 static void br_make_forwarding(struct net_bridge_port *p)
371 if (p->state == BR_STATE_BLOCKING) {
372 if (p->br->stp_enabled == BR_KERNEL_STP)
373 p->state = BR_STATE_LISTENING;
375 p->state = BR_STATE_LEARNING;
378 mod_timer(&p->forward_delay_timer, jiffies + p->br->forward_delay); }
381 /* called under bridge lock */
382 void br_port_state_selection(struct net_bridge *br)
384 struct net_bridge_port *p;
386 /* Don't change port states if userspace is handling STP */
387 if (br->stp_enabled == BR_USER_STP)
390 list_for_each_entry(p, &br->port_list, list) {
391 if (p->state != BR_STATE_DISABLED) {
392 if (p->port_no == br->root_port) {
393 p->config_pending = 0;
394 p->topology_change_ack = 0;
395 br_make_forwarding(p);
396 } else if (br_is_designated_port(p)) {
397 del_timer(&p->message_age_timer);
398 br_make_forwarding(p);
400 p->config_pending = 0;
401 p->topology_change_ack = 0;
409 /* called under bridge lock */
410 static inline void br_topology_change_acknowledge(struct net_bridge_port *p)
412 p->topology_change_ack = 1;
413 br_transmit_config(p);
416 /* called under bridge lock */
417 void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
419 struct net_bridge *br;
423 was_root = br_is_root_bridge(br);
425 if (br_supersedes_port_info(p, bpdu)) {
426 br_record_config_information(p, bpdu);
427 br_configuration_update(br);
428 br_port_state_selection(br);
430 if (!br_is_root_bridge(br) && was_root) {
431 del_timer(&br->hello_timer);
432 if (br->topology_change_detected) {
433 del_timer(&br->topology_change_timer);
436 mod_timer(&br->tcn_timer,
437 jiffies + br->bridge_hello_time);
441 if (p->port_no == br->root_port) {
442 br_record_config_timeout_values(br, bpdu);
443 br_config_bpdu_generation(br);
444 if (bpdu->topology_change_ack)
445 br_topology_change_acknowledged(br);
447 } else if (br_is_designated_port(p)) {
452 /* called under bridge lock */
453 void br_received_tcn_bpdu(struct net_bridge_port *p)
455 if (br_is_designated_port(p)) {
456 pr_info("%s: received tcn bpdu on port %i(%s)\n",
457 p->br->dev->name, p->port_no, p->dev->name);
459 br_topology_change_detection(p->br);
460 br_topology_change_acknowledge(p);