[NET]: Share correct feature code between bridging and bonding
[linux-2.6.git] / net / bridge / br_stp.c
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 #include <linux/kernel.h>
16
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
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",
31 };
32
33 void br_log_state(const struct net_bridge_port *p)
34 {
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]);
38
39 }
40
41 /* called under bridge lock */
42 struct 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 */
55 static int br_should_become_root_port(const struct net_bridge_port *p,
56                                       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 */
106 static 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 */
130 void 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 */
145 void 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;
181                 mod_timer(&p->hold_timer,
182                           round_jiffies(jiffies + BR_HOLD_TIME));
183         }
184 }
185
186 /* called under bridge lock */
187 static inline void br_record_config_information(struct net_bridge_port *p,
188                                                 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
195         mod_timer(&p->message_age_timer, jiffies
196                   + (p->br->max_age - bpdu->message_age));
197 }
198
199 /* called under bridge lock */
200 static inline void br_record_config_timeout_values(struct net_bridge *br,
201                                             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 */
210 void 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 */
216 static 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 */
246 static 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 */
259 static 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 */
290 static 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 */
297 void 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 */
317 void 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 */
329 static inline void br_reply(struct net_bridge_port *p)
330 {
331         br_transmit_config(p);
332 }
333
334 /* called under bridge lock */
335 void 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 */
342 void 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 */
355 static 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 */
370 static void br_make_forwarding(struct net_bridge_port *p)
371 {
372         if (p->state == BR_STATE_BLOCKING) {
373                 if (p->br->stp_enabled == BR_KERNEL_STP)
374                         p->state = BR_STATE_LISTENING;
375                 else
376                         p->state = BR_STATE_LEARNING;
377
378                 br_log_state(p);
379                 mod_timer(&p->forward_delay_timer, jiffies + p->br->forward_delay);     }
380 }
381
382 /* called under bridge lock */
383 void br_port_state_selection(struct net_bridge *br)
384 {
385         struct net_bridge_port *p;
386
387         /* Don't change port states if userspace is handling STP */
388         if (br->stp_enabled == BR_USER_STP)
389                 return;
390
391         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 */
411 static 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 */
418 void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
419 {
420         struct net_bridge *br;
421         int was_root;
422
423         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
437                                 mod_timer(&br->tcn_timer,
438                                           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                 }
448         } else if (br_is_designated_port(p)) {
449                 br_reply(p);
450         }
451 }
452
453 /* called under bridge lock */
454 void 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 }