2 * Spanning tree protocol; generic parts
3 * Linux ethernet bridge
6 * Lennert Buytenhek <buytenh@gnu.org>
8 * 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.
13 #include <linux/kernel.h>
14 #include <linux/rculist.h>
16 #include "br_private.h"
17 #include "br_private_stp.h"
19 /* since time values in bpdu are in jiffies and then scaled (1/256)
20 * before sending, make sure that is at least one.
22 #define MESSAGE_AGE_INCR ((HZ < 256) ? 1 : (HZ/256))
24 static const char *const br_port_state_names[] = {
25 [BR_STATE_DISABLED] = "disabled",
26 [BR_STATE_LISTENING] = "listening",
27 [BR_STATE_LEARNING] = "learning",
28 [BR_STATE_FORWARDING] = "forwarding",
29 [BR_STATE_BLOCKING] = "blocking",
32 void br_log_state(const struct net_bridge_port *p)
34 br_info(p->br, "port %u(%s) entering %s state\n",
35 (unsigned) p->port_no, p->dev->name,
36 br_port_state_names[p->state]);
39 /* called under bridge lock */
40 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
42 struct net_bridge_port *p;
44 list_for_each_entry_rcu(p, &br->port_list, list) {
45 if (p->port_no == port_no)
52 /* called under bridge lock */
53 static int br_should_become_root_port(const struct net_bridge_port *p,
56 struct net_bridge *br;
57 struct net_bridge_port *rp;
61 if (p->state == BR_STATE_DISABLED ||
62 br_is_designated_port(p))
65 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
71 rp = br_get_port(br, root_port);
73 t = memcmp(&p->designated_root, &rp->designated_root, 8);
79 if (p->designated_cost + p->path_cost <
80 rp->designated_cost + rp->path_cost)
82 else if (p->designated_cost + p->path_cost >
83 rp->designated_cost + rp->path_cost)
86 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
92 if (p->designated_port < rp->designated_port)
94 else if (p->designated_port > rp->designated_port)
97 if (p->port_id < rp->port_id)
103 /* called under bridge lock */
104 static void br_root_selection(struct net_bridge *br)
106 struct net_bridge_port *p;
109 list_for_each_entry(p, &br->port_list, list) {
110 if (br_should_become_root_port(p, root_port))
111 root_port = p->port_no;
115 br->root_port = root_port;
118 br->designated_root = br->bridge_id;
119 br->root_path_cost = 0;
121 p = br_get_port(br, root_port);
122 br->designated_root = p->designated_root;
123 br->root_path_cost = p->designated_cost + p->path_cost;
127 /* called under bridge lock */
128 void br_become_root_bridge(struct net_bridge *br)
130 br->max_age = br->bridge_max_age;
131 br->hello_time = br->bridge_hello_time;
132 br->forward_delay = br->bridge_forward_delay;
133 br_topology_change_detection(br);
134 del_timer(&br->tcn_timer);
136 if (br->dev->flags & IFF_UP) {
137 br_config_bpdu_generation(br);
138 mod_timer(&br->hello_timer, jiffies + br->hello_time);
142 /* called under bridge lock */
143 void br_transmit_config(struct net_bridge_port *p)
145 struct br_config_bpdu bpdu;
146 struct net_bridge *br;
149 if (timer_pending(&p->hold_timer)) {
150 p->config_pending = 1;
156 bpdu.topology_change = br->topology_change;
157 bpdu.topology_change_ack = p->topology_change_ack;
158 bpdu.root = br->designated_root;
159 bpdu.root_path_cost = br->root_path_cost;
160 bpdu.bridge_id = br->bridge_id;
161 bpdu.port_id = p->port_id;
162 if (br_is_root_bridge(br))
163 bpdu.message_age = 0;
165 struct net_bridge_port *root
166 = br_get_port(br, br->root_port);
167 bpdu.message_age = br->max_age
168 - (root->message_age_timer.expires - jiffies)
171 bpdu.max_age = br->max_age;
172 bpdu.hello_time = br->hello_time;
173 bpdu.forward_delay = br->forward_delay;
175 if (bpdu.message_age < br->max_age) {
176 br_send_config_bpdu(p, &bpdu);
177 p->topology_change_ack = 0;
178 p->config_pending = 0;
179 mod_timer(&p->hold_timer,
180 round_jiffies(jiffies + BR_HOLD_TIME));
184 /* called under bridge lock */
185 static inline void br_record_config_information(struct net_bridge_port *p,
186 const struct br_config_bpdu *bpdu)
188 p->designated_root = bpdu->root;
189 p->designated_cost = bpdu->root_path_cost;
190 p->designated_bridge = bpdu->bridge_id;
191 p->designated_port = bpdu->port_id;
193 mod_timer(&p->message_age_timer, jiffies
194 + (p->br->max_age - bpdu->message_age));
197 /* called under bridge lock */
198 static inline void br_record_config_timeout_values(struct net_bridge *br,
199 const struct br_config_bpdu *bpdu)
201 br->max_age = bpdu->max_age;
202 br->hello_time = bpdu->hello_time;
203 br->forward_delay = bpdu->forward_delay;
204 br->topology_change = bpdu->topology_change;
207 /* called under bridge lock */
208 void br_transmit_tcn(struct net_bridge *br)
210 br_send_tcn_bpdu(br_get_port(br, br->root_port));
213 /* called under bridge lock */
214 static int br_should_become_designated_port(const struct net_bridge_port *p)
216 struct net_bridge *br;
220 if (br_is_designated_port(p))
223 if (memcmp(&p->designated_root, &br->designated_root, 8))
226 if (br->root_path_cost < p->designated_cost)
228 else if (br->root_path_cost > p->designated_cost)
231 t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
237 if (p->port_id < p->designated_port)
243 /* called under bridge lock */
244 static void br_designated_port_selection(struct net_bridge *br)
246 struct net_bridge_port *p;
248 list_for_each_entry(p, &br->port_list, list) {
249 if (p->state != BR_STATE_DISABLED &&
250 br_should_become_designated_port(p))
251 br_become_designated_port(p);
256 /* called under bridge lock */
257 static int br_supersedes_port_info(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
261 t = memcmp(&bpdu->root, &p->designated_root, 8);
267 if (bpdu->root_path_cost < p->designated_cost)
269 else if (bpdu->root_path_cost > p->designated_cost)
272 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
278 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
281 if (bpdu->port_id <= p->designated_port)
287 /* called under bridge lock */
288 static inline void br_topology_change_acknowledged(struct net_bridge *br)
290 br->topology_change_detected = 0;
291 del_timer(&br->tcn_timer);
294 /* called under bridge lock */
295 void br_topology_change_detection(struct net_bridge *br)
297 int isroot = br_is_root_bridge(br);
299 if (br->stp_enabled != BR_KERNEL_STP)
302 br_info(br, "topology change detected, %s\n",
303 isroot ? "propagating" : "sending tcn bpdu");
306 br->topology_change = 1;
307 mod_timer(&br->topology_change_timer, jiffies
308 + br->bridge_forward_delay + br->bridge_max_age);
309 } else if (!br->topology_change_detected) {
311 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
314 br->topology_change_detected = 1;
317 /* called under bridge lock */
318 void br_config_bpdu_generation(struct net_bridge *br)
320 struct net_bridge_port *p;
322 list_for_each_entry(p, &br->port_list, list) {
323 if (p->state != BR_STATE_DISABLED &&
324 br_is_designated_port(p))
325 br_transmit_config(p);
329 /* called under bridge lock */
330 static inline void br_reply(struct net_bridge_port *p)
332 br_transmit_config(p);
335 /* called under bridge lock */
336 void br_configuration_update(struct net_bridge *br)
338 br_root_selection(br);
339 br_designated_port_selection(br);
342 /* called under bridge lock */
343 void br_become_designated_port(struct net_bridge_port *p)
345 struct net_bridge *br;
348 p->designated_root = br->designated_root;
349 p->designated_cost = br->root_path_cost;
350 p->designated_bridge = br->bridge_id;
351 p->designated_port = p->port_id;
355 /* called under bridge lock */
356 static void br_make_blocking(struct net_bridge_port *p)
358 if (p->state != BR_STATE_DISABLED &&
359 p->state != BR_STATE_BLOCKING) {
360 if (p->state == BR_STATE_FORWARDING ||
361 p->state == BR_STATE_LEARNING)
362 br_topology_change_detection(p->br);
364 p->state = BR_STATE_BLOCKING;
366 del_timer(&p->forward_delay_timer);
370 /* called under bridge lock */
371 static void br_make_forwarding(struct net_bridge_port *p)
373 struct net_bridge *br = p->br;
375 if (p->state != BR_STATE_BLOCKING)
378 if (br->forward_delay == 0) {
379 p->state = BR_STATE_FORWARDING;
380 br_topology_change_detection(br);
381 del_timer(&p->forward_delay_timer);
383 else if (p->br->stp_enabled == BR_KERNEL_STP)
384 p->state = BR_STATE_LISTENING;
386 p->state = BR_STATE_LEARNING;
388 br_multicast_enable_port(p);
392 if (br->forward_delay != 0)
393 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
396 /* called under bridge lock */
397 void br_port_state_selection(struct net_bridge *br)
399 struct net_bridge_port *p;
400 unsigned int liveports = 0;
402 /* Don't change port states if userspace is handling STP */
403 if (br->stp_enabled == BR_USER_STP)
406 list_for_each_entry(p, &br->port_list, list) {
407 if (p->state == BR_STATE_DISABLED)
410 if (p->port_no == br->root_port) {
411 p->config_pending = 0;
412 p->topology_change_ack = 0;
413 br_make_forwarding(p);
414 } else if (br_is_designated_port(p)) {
415 del_timer(&p->message_age_timer);
416 br_make_forwarding(p);
418 p->config_pending = 0;
419 p->topology_change_ack = 0;
423 if (p->state == BR_STATE_FORWARDING)
428 netif_carrier_off(br->dev);
430 netif_carrier_on(br->dev);
433 /* called under bridge lock */
434 static inline void br_topology_change_acknowledge(struct net_bridge_port *p)
436 p->topology_change_ack = 1;
437 br_transmit_config(p);
440 /* called under bridge lock */
441 void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
443 struct net_bridge *br;
447 was_root = br_is_root_bridge(br);
449 if (br_supersedes_port_info(p, bpdu)) {
450 br_record_config_information(p, bpdu);
451 br_configuration_update(br);
452 br_port_state_selection(br);
454 if (!br_is_root_bridge(br) && was_root) {
455 del_timer(&br->hello_timer);
456 if (br->topology_change_detected) {
457 del_timer(&br->topology_change_timer);
460 mod_timer(&br->tcn_timer,
461 jiffies + br->bridge_hello_time);
465 if (p->port_no == br->root_port) {
466 br_record_config_timeout_values(br, bpdu);
467 br_config_bpdu_generation(br);
468 if (bpdu->topology_change_ack)
469 br_topology_change_acknowledged(br);
471 } else if (br_is_designated_port(p)) {
476 /* called under bridge lock */
477 void br_received_tcn_bpdu(struct net_bridge_port *p)
479 if (br_is_designated_port(p)) {
480 br_info(p->br, "port %u(%s) received tcn bpdu\n",
481 (unsigned) p->port_no, p->dev->name);
483 br_topology_change_detection(p->br);
484 br_topology_change_acknowledge(p);