bridge: Adjust min age inc for HZ > 256
[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  *      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>
14 #include <linux/rculist.h>
15
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 STP tick.
21  */
22 #define MESSAGE_AGE_INCR        ((HZ / 256) + 1)
23
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",
30 };
31
32 void br_log_state(const struct net_bridge_port *p)
33 {
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]);
37 }
38
39 /* called under bridge lock */
40 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
41 {
42         struct net_bridge_port *p;
43
44         list_for_each_entry_rcu(p, &br->port_list, list) {
45                 if (p->port_no == port_no)
46                         return p;
47         }
48
49         return NULL;
50 }
51
52 /* called under bridge lock */
53 static int br_should_become_root_port(const struct net_bridge_port *p,
54                                       u16 root_port)
55 {
56         struct net_bridge *br;
57         struct net_bridge_port *rp;
58         int t;
59
60         br = p->br;
61         if (p->state == BR_STATE_DISABLED ||
62             br_is_designated_port(p))
63                 return 0;
64
65         if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
66                 return 0;
67
68         if (!root_port)
69                 return 1;
70
71         rp = br_get_port(br, root_port);
72
73         t = memcmp(&p->designated_root, &rp->designated_root, 8);
74         if (t < 0)
75                 return 1;
76         else if (t > 0)
77                 return 0;
78
79         if (p->designated_cost + p->path_cost <
80             rp->designated_cost + rp->path_cost)
81                 return 1;
82         else if (p->designated_cost + p->path_cost >
83                  rp->designated_cost + rp->path_cost)
84                 return 0;
85
86         t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
87         if (t < 0)
88                 return 1;
89         else if (t > 0)
90                 return 0;
91
92         if (p->designated_port < rp->designated_port)
93                 return 1;
94         else if (p->designated_port > rp->designated_port)
95                 return 0;
96
97         if (p->port_id < rp->port_id)
98                 return 1;
99
100         return 0;
101 }
102
103 /* called under bridge lock */
104 static void br_root_selection(struct net_bridge *br)
105 {
106         struct net_bridge_port *p;
107         u16 root_port = 0;
108
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;
112         }
113
114         br->root_port = root_port;
115
116         if (!root_port) {
117                 br->designated_root = br->bridge_id;
118                 br->root_path_cost = 0;
119         } else {
120                 p = br_get_port(br, root_port);
121                 br->designated_root = p->designated_root;
122                 br->root_path_cost = p->designated_cost + p->path_cost;
123         }
124 }
125
126 /* called under bridge lock */
127 void br_become_root_bridge(struct net_bridge *br)
128 {
129         br->max_age = br->bridge_max_age;
130         br->hello_time = br->bridge_hello_time;
131         br->forward_delay = br->bridge_forward_delay;
132         br_topology_change_detection(br);
133         del_timer(&br->tcn_timer);
134
135         if (br->dev->flags & IFF_UP) {
136                 br_config_bpdu_generation(br);
137                 mod_timer(&br->hello_timer, jiffies + br->hello_time);
138         }
139 }
140
141 /* called under bridge lock */
142 void br_transmit_config(struct net_bridge_port *p)
143 {
144         struct br_config_bpdu bpdu;
145         struct net_bridge *br;
146
147         if (timer_pending(&p->hold_timer)) {
148                 p->config_pending = 1;
149                 return;
150         }
151
152         br = p->br;
153
154         bpdu.topology_change = br->topology_change;
155         bpdu.topology_change_ack = p->topology_change_ack;
156         bpdu.root = br->designated_root;
157         bpdu.root_path_cost = br->root_path_cost;
158         bpdu.bridge_id = br->bridge_id;
159         bpdu.port_id = p->port_id;
160         if (br_is_root_bridge(br))
161                 bpdu.message_age = 0;
162         else {
163                 struct net_bridge_port *root
164                         = br_get_port(br, br->root_port);
165                 bpdu.message_age = (jiffies - root->designated_age)
166                         + MESSAGE_AGE_INCR;
167         }
168         bpdu.max_age = br->max_age;
169         bpdu.hello_time = br->hello_time;
170         bpdu.forward_delay = br->forward_delay;
171
172         if (bpdu.message_age < br->max_age) {
173                 br_send_config_bpdu(p, &bpdu);
174                 p->topology_change_ack = 0;
175                 p->config_pending = 0;
176                 mod_timer(&p->hold_timer,
177                           round_jiffies(jiffies + BR_HOLD_TIME));
178         }
179 }
180
181 /* called under bridge lock */
182 static void br_record_config_information(struct net_bridge_port *p,
183                                          const struct br_config_bpdu *bpdu)
184 {
185         p->designated_root = bpdu->root;
186         p->designated_cost = bpdu->root_path_cost;
187         p->designated_bridge = bpdu->bridge_id;
188         p->designated_port = bpdu->port_id;
189         p->designated_age = jiffies + bpdu->message_age;
190
191         mod_timer(&p->message_age_timer, jiffies
192                   + (p->br->max_age - bpdu->message_age));
193 }
194
195 /* called under bridge lock */
196 static void br_record_config_timeout_values(struct net_bridge *br,
197                                             const struct br_config_bpdu *bpdu)
198 {
199         br->max_age = bpdu->max_age;
200         br->hello_time = bpdu->hello_time;
201         br->forward_delay = bpdu->forward_delay;
202         br->topology_change = bpdu->topology_change;
203 }
204
205 /* called under bridge lock */
206 void br_transmit_tcn(struct net_bridge *br)
207 {
208         br_send_tcn_bpdu(br_get_port(br, br->root_port));
209 }
210
211 /* called under bridge lock */
212 static int br_should_become_designated_port(const struct net_bridge_port *p)
213 {
214         struct net_bridge *br;
215         int t;
216
217         br = p->br;
218         if (br_is_designated_port(p))
219                 return 1;
220
221         if (memcmp(&p->designated_root, &br->designated_root, 8))
222                 return 1;
223
224         if (br->root_path_cost < p->designated_cost)
225                 return 1;
226         else if (br->root_path_cost > p->designated_cost)
227                 return 0;
228
229         t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
230         if (t < 0)
231                 return 1;
232         else if (t > 0)
233                 return 0;
234
235         if (p->port_id < p->designated_port)
236                 return 1;
237
238         return 0;
239 }
240
241 /* called under bridge lock */
242 static void br_designated_port_selection(struct net_bridge *br)
243 {
244         struct net_bridge_port *p;
245
246         list_for_each_entry(p, &br->port_list, list) {
247                 if (p->state != BR_STATE_DISABLED &&
248                     br_should_become_designated_port(p))
249                         br_become_designated_port(p);
250
251         }
252 }
253
254 /* called under bridge lock */
255 static int br_supersedes_port_info(const struct net_bridge_port *p,
256                                    const struct br_config_bpdu *bpdu)
257 {
258         int t;
259
260         t = memcmp(&bpdu->root, &p->designated_root, 8);
261         if (t < 0)
262                 return 1;
263         else if (t > 0)
264                 return 0;
265
266         if (bpdu->root_path_cost < p->designated_cost)
267                 return 1;
268         else if (bpdu->root_path_cost > p->designated_cost)
269                 return 0;
270
271         t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
272         if (t < 0)
273                 return 1;
274         else if (t > 0)
275                 return 0;
276
277         if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
278                 return 1;
279
280         if (bpdu->port_id <= p->designated_port)
281                 return 1;
282
283         return 0;
284 }
285
286 /* called under bridge lock */
287 static void br_topology_change_acknowledged(struct net_bridge *br)
288 {
289         br->topology_change_detected = 0;
290         del_timer(&br->tcn_timer);
291 }
292
293 /* called under bridge lock */
294 void br_topology_change_detection(struct net_bridge *br)
295 {
296         int isroot = br_is_root_bridge(br);
297
298         if (br->stp_enabled != BR_KERNEL_STP)
299                 return;
300
301         br_info(br, "topology change detected, %s\n",
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 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                 br_ifinfo_notify(RTM_NEWLINK, p);
366
367                 del_timer(&p->forward_delay_timer);
368         }
369 }
370
371 /* called under bridge lock */
372 static void br_make_forwarding(struct net_bridge_port *p)
373 {
374         struct net_bridge *br = p->br;
375
376         if (p->state != BR_STATE_BLOCKING)
377                 return;
378
379         if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) {
380                 p->state = BR_STATE_FORWARDING;
381                 br_topology_change_detection(br);
382                 del_timer(&p->forward_delay_timer);
383         } else if (br->stp_enabled == BR_KERNEL_STP)
384                 p->state = BR_STATE_LISTENING;
385         else
386                 p->state = BR_STATE_LEARNING;
387
388         br_multicast_enable_port(p);
389         br_log_state(p);
390         br_ifinfo_notify(RTM_NEWLINK, p);
391
392         if (br->forward_delay != 0)
393                 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
394 }
395
396 /* called under bridge lock */
397 void br_port_state_selection(struct net_bridge *br)
398 {
399         struct net_bridge_port *p;
400         unsigned int liveports = 0;
401
402         list_for_each_entry(p, &br->port_list, list) {
403                 if (p->state == BR_STATE_DISABLED)
404                         continue;
405
406                 /* Don't change port states if userspace is handling STP */
407                 if (br->stp_enabled != BR_USER_STP) {
408                         if (p->port_no == br->root_port) {
409                                 p->config_pending = 0;
410                                 p->topology_change_ack = 0;
411                                 br_make_forwarding(p);
412                         } else if (br_is_designated_port(p)) {
413                                 del_timer(&p->message_age_timer);
414                                 br_make_forwarding(p);
415                         } else {
416                                 p->config_pending = 0;
417                                 p->topology_change_ack = 0;
418                                 br_make_blocking(p);
419                         }
420                 }
421
422                 if (p->state == BR_STATE_FORWARDING)
423                         ++liveports;
424         }
425
426         if (liveports == 0)
427                 netif_carrier_off(br->dev);
428         else
429                 netif_carrier_on(br->dev);
430 }
431
432 /* called under bridge lock */
433 static void br_topology_change_acknowledge(struct net_bridge_port *p)
434 {
435         p->topology_change_ack = 1;
436         br_transmit_config(p);
437 }
438
439 /* called under bridge lock */
440 void br_received_config_bpdu(struct net_bridge_port *p,
441                              const struct br_config_bpdu *bpdu)
442 {
443         struct net_bridge *br;
444         int was_root;
445
446         br = p->br;
447         was_root = br_is_root_bridge(br);
448
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);
453
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);
458                                 br_transmit_tcn(br);
459
460                                 mod_timer(&br->tcn_timer,
461                                           jiffies + br->bridge_hello_time);
462                         }
463                 }
464
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);
470                 }
471         } else if (br_is_designated_port(p)) {
472                 br_reply(p);
473         }
474 }
475
476 /* called under bridge lock */
477 void br_received_tcn_bpdu(struct net_bridge_port *p)
478 {
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);
482
483                 br_topology_change_detection(p->br);
484                 br_topology_change_acknowledge(p);
485         }
486 }
487
488 /* Change bridge STP parameter */
489 int br_set_hello_time(struct net_bridge *br, unsigned long val)
490 {
491         unsigned long t = clock_t_to_jiffies(val);
492
493         if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME)
494                 return -ERANGE;
495
496         spin_lock_bh(&br->lock);
497         br->bridge_hello_time = t;
498         if (br_is_root_bridge(br))
499                 br->hello_time = br->bridge_hello_time;
500         spin_unlock_bh(&br->lock);
501         return 0;
502 }
503
504 int br_set_max_age(struct net_bridge *br, unsigned long val)
505 {
506         unsigned long t = clock_t_to_jiffies(val);
507
508         if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE)
509                 return -ERANGE;
510
511         spin_lock_bh(&br->lock);
512         br->bridge_max_age = t;
513         if (br_is_root_bridge(br))
514                 br->max_age = br->bridge_max_age;
515         spin_unlock_bh(&br->lock);
516         return 0;
517
518 }
519
520 int br_set_forward_delay(struct net_bridge *br, unsigned long val)
521 {
522         unsigned long t = clock_t_to_jiffies(val);
523
524         if (br->stp_enabled != BR_NO_STP &&
525             (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
526                 return -ERANGE;
527
528         spin_lock_bh(&br->lock);
529         br->bridge_forward_delay = t;
530         if (br_is_root_bridge(br))
531                 br->forward_delay = br->bridge_forward_delay;
532         spin_unlock_bh(&br->lock);
533         return 0;
534 }