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1 | /* net/sched/sch_teql.c "True" (or "trivial") link equalizer. | |
2 | * | |
3 | * This program is free software; you can redistribute it and/or | |
4 | * modify it under the terms of the GNU General Public License | |
5 | * as published by the Free Software Foundation; either version | |
6 | * 2 of the License, or (at your option) any later version. | |
7 | * | |
8 | * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> | |
9 | */ | |
10 | ||
11 | #include <linux/module.h> | |
12 | #include <linux/types.h> | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/string.h> | |
16 | #include <linux/errno.h> | |
17 | #include <linux/if_arp.h> | |
18 | #include <linux/netdevice.h> | |
19 | #include <linux/init.h> | |
20 | #include <linux/skbuff.h> | |
21 | #include <linux/moduleparam.h> | |
22 | #include <net/dst.h> | |
23 | #include <net/neighbour.h> | |
24 | #include <net/pkt_sched.h> | |
25 | ||
26 | /* | |
27 | How to setup it. | |
28 | ---------------- | |
29 | ||
30 | After loading this module you will find a new device teqlN | |
31 | and new qdisc with the same name. To join a slave to the equalizer | |
32 | you should just set this qdisc on a device f.e. | |
33 | ||
34 | # tc qdisc add dev eth0 root teql0 | |
35 | # tc qdisc add dev eth1 root teql0 | |
36 | ||
37 | That's all. Full PnP 8) | |
38 | ||
39 | Applicability. | |
40 | -------------- | |
41 | ||
42 | 1. Slave devices MUST be active devices, i.e., they must raise the tbusy | |
43 | signal and generate EOI events. If you want to equalize virtual devices | |
44 | like tunnels, use a normal eql device. | |
45 | 2. This device puts no limitations on physical slave characteristics | |
46 | f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-) | |
47 | Certainly, large difference in link speeds will make the resulting | |
48 | eqalized link unusable, because of huge packet reordering. | |
49 | I estimate an upper useful difference as ~10 times. | |
50 | 3. If the slave requires address resolution, only protocols using | |
51 | neighbour cache (IPv4/IPv6) will work over the equalized link. | |
52 | Other protocols are still allowed to use the slave device directly, | |
53 | which will not break load balancing, though native slave | |
54 | traffic will have the highest priority. */ | |
55 | ||
56 | struct teql_master { | |
57 | struct Qdisc_ops qops; | |
58 | struct net_device *dev; | |
59 | struct Qdisc *slaves; | |
60 | struct list_head master_list; | |
61 | unsigned long tx_bytes; | |
62 | unsigned long tx_packets; | |
63 | unsigned long tx_errors; | |
64 | unsigned long tx_dropped; | |
65 | }; | |
66 | ||
67 | struct teql_sched_data { | |
68 | struct Qdisc *next; | |
69 | struct teql_master *m; | |
70 | struct sk_buff_head q; | |
71 | }; | |
72 | ||
73 | #define NEXT_SLAVE(q) (((struct teql_sched_data *)qdisc_priv(q))->next) | |
74 | ||
75 | #define FMASK (IFF_BROADCAST | IFF_POINTOPOINT) | |
76 | ||
77 | /* "teql*" qdisc routines */ | |
78 | ||
79 | static int | |
80 | teql_enqueue(struct sk_buff *skb, struct Qdisc *sch) | |
81 | { | |
82 | struct net_device *dev = qdisc_dev(sch); | |
83 | struct teql_sched_data *q = qdisc_priv(sch); | |
84 | ||
85 | if (q->q.qlen < dev->tx_queue_len) { | |
86 | __skb_queue_tail(&q->q, skb); | |
87 | return NET_XMIT_SUCCESS; | |
88 | } | |
89 | ||
90 | return qdisc_drop(skb, sch); | |
91 | } | |
92 | ||
93 | static struct sk_buff * | |
94 | teql_dequeue(struct Qdisc *sch) | |
95 | { | |
96 | struct teql_sched_data *dat = qdisc_priv(sch); | |
97 | struct netdev_queue *dat_queue; | |
98 | struct sk_buff *skb; | |
99 | struct Qdisc *q; | |
100 | ||
101 | skb = __skb_dequeue(&dat->q); | |
102 | dat_queue = netdev_get_tx_queue(dat->m->dev, 0); | |
103 | q = rcu_dereference_bh(dat_queue->qdisc); | |
104 | ||
105 | if (skb == NULL) { | |
106 | struct net_device *m = qdisc_dev(q); | |
107 | if (m) { | |
108 | dat->m->slaves = sch; | |
109 | netif_wake_queue(m); | |
110 | } | |
111 | } else { | |
112 | qdisc_bstats_update(sch, skb); | |
113 | } | |
114 | sch->q.qlen = dat->q.qlen + q->q.qlen; | |
115 | return skb; | |
116 | } | |
117 | ||
118 | static struct sk_buff * | |
119 | teql_peek(struct Qdisc *sch) | |
120 | { | |
121 | /* teql is meant to be used as root qdisc */ | |
122 | return NULL; | |
123 | } | |
124 | ||
125 | static void | |
126 | teql_reset(struct Qdisc *sch) | |
127 | { | |
128 | struct teql_sched_data *dat = qdisc_priv(sch); | |
129 | ||
130 | skb_queue_purge(&dat->q); | |
131 | sch->q.qlen = 0; | |
132 | } | |
133 | ||
134 | static void | |
135 | teql_destroy(struct Qdisc *sch) | |
136 | { | |
137 | struct Qdisc *q, *prev; | |
138 | struct teql_sched_data *dat = qdisc_priv(sch); | |
139 | struct teql_master *master = dat->m; | |
140 | ||
141 | prev = master->slaves; | |
142 | if (prev) { | |
143 | do { | |
144 | q = NEXT_SLAVE(prev); | |
145 | if (q == sch) { | |
146 | NEXT_SLAVE(prev) = NEXT_SLAVE(q); | |
147 | if (q == master->slaves) { | |
148 | master->slaves = NEXT_SLAVE(q); | |
149 | if (q == master->slaves) { | |
150 | struct netdev_queue *txq; | |
151 | spinlock_t *root_lock; | |
152 | ||
153 | txq = netdev_get_tx_queue(master->dev, 0); | |
154 | master->slaves = NULL; | |
155 | ||
156 | root_lock = qdisc_root_sleeping_lock(rtnl_dereference(txq->qdisc)); | |
157 | spin_lock_bh(root_lock); | |
158 | qdisc_reset(rtnl_dereference(txq->qdisc)); | |
159 | spin_unlock_bh(root_lock); | |
160 | } | |
161 | } | |
162 | skb_queue_purge(&dat->q); | |
163 | break; | |
164 | } | |
165 | ||
166 | } while ((prev = q) != master->slaves); | |
167 | } | |
168 | } | |
169 | ||
170 | static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt) | |
171 | { | |
172 | struct net_device *dev = qdisc_dev(sch); | |
173 | struct teql_master *m = (struct teql_master *)sch->ops; | |
174 | struct teql_sched_data *q = qdisc_priv(sch); | |
175 | ||
176 | if (dev->hard_header_len > m->dev->hard_header_len) | |
177 | return -EINVAL; | |
178 | ||
179 | if (m->dev == dev) | |
180 | return -ELOOP; | |
181 | ||
182 | q->m = m; | |
183 | ||
184 | skb_queue_head_init(&q->q); | |
185 | ||
186 | if (m->slaves) { | |
187 | if (m->dev->flags & IFF_UP) { | |
188 | if ((m->dev->flags & IFF_POINTOPOINT && | |
189 | !(dev->flags & IFF_POINTOPOINT)) || | |
190 | (m->dev->flags & IFF_BROADCAST && | |
191 | !(dev->flags & IFF_BROADCAST)) || | |
192 | (m->dev->flags & IFF_MULTICAST && | |
193 | !(dev->flags & IFF_MULTICAST)) || | |
194 | dev->mtu < m->dev->mtu) | |
195 | return -EINVAL; | |
196 | } else { | |
197 | if (!(dev->flags&IFF_POINTOPOINT)) | |
198 | m->dev->flags &= ~IFF_POINTOPOINT; | |
199 | if (!(dev->flags&IFF_BROADCAST)) | |
200 | m->dev->flags &= ~IFF_BROADCAST; | |
201 | if (!(dev->flags&IFF_MULTICAST)) | |
202 | m->dev->flags &= ~IFF_MULTICAST; | |
203 | if (dev->mtu < m->dev->mtu) | |
204 | m->dev->mtu = dev->mtu; | |
205 | } | |
206 | q->next = NEXT_SLAVE(m->slaves); | |
207 | NEXT_SLAVE(m->slaves) = sch; | |
208 | } else { | |
209 | q->next = sch; | |
210 | m->slaves = sch; | |
211 | m->dev->mtu = dev->mtu; | |
212 | m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK); | |
213 | } | |
214 | return 0; | |
215 | } | |
216 | ||
217 | ||
218 | static int | |
219 | __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, | |
220 | struct net_device *dev, struct netdev_queue *txq, | |
221 | struct dst_entry *dst) | |
222 | { | |
223 | struct neighbour *n; | |
224 | int err = 0; | |
225 | ||
226 | n = dst_neigh_lookup_skb(dst, skb); | |
227 | if (!n) | |
228 | return -ENOENT; | |
229 | ||
230 | if (dst->dev != dev) { | |
231 | struct neighbour *mn; | |
232 | ||
233 | mn = __neigh_lookup_errno(n->tbl, n->primary_key, dev); | |
234 | neigh_release(n); | |
235 | if (IS_ERR(mn)) | |
236 | return PTR_ERR(mn); | |
237 | n = mn; | |
238 | } | |
239 | ||
240 | if (neigh_event_send(n, skb_res) == 0) { | |
241 | int err; | |
242 | char haddr[MAX_ADDR_LEN]; | |
243 | ||
244 | neigh_ha_snapshot(haddr, n, dev); | |
245 | err = dev_hard_header(skb, dev, ntohs(tc_skb_protocol(skb)), | |
246 | haddr, NULL, skb->len); | |
247 | ||
248 | if (err < 0) | |
249 | err = -EINVAL; | |
250 | } else { | |
251 | err = (skb_res == NULL) ? -EAGAIN : 1; | |
252 | } | |
253 | neigh_release(n); | |
254 | return err; | |
255 | } | |
256 | ||
257 | static inline int teql_resolve(struct sk_buff *skb, | |
258 | struct sk_buff *skb_res, | |
259 | struct net_device *dev, | |
260 | struct netdev_queue *txq) | |
261 | { | |
262 | struct dst_entry *dst = skb_dst(skb); | |
263 | int res; | |
264 | ||
265 | if (rcu_access_pointer(txq->qdisc) == &noop_qdisc) | |
266 | return -ENODEV; | |
267 | ||
268 | if (!dev->header_ops || !dst) | |
269 | return 0; | |
270 | ||
271 | rcu_read_lock(); | |
272 | res = __teql_resolve(skb, skb_res, dev, txq, dst); | |
273 | rcu_read_unlock(); | |
274 | ||
275 | return res; | |
276 | } | |
277 | ||
278 | static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev) | |
279 | { | |
280 | struct teql_master *master = netdev_priv(dev); | |
281 | struct Qdisc *start, *q; | |
282 | int busy; | |
283 | int nores; | |
284 | int subq = skb_get_queue_mapping(skb); | |
285 | struct sk_buff *skb_res = NULL; | |
286 | ||
287 | start = master->slaves; | |
288 | ||
289 | restart: | |
290 | nores = 0; | |
291 | busy = 0; | |
292 | ||
293 | q = start; | |
294 | if (!q) | |
295 | goto drop; | |
296 | ||
297 | do { | |
298 | struct net_device *slave = qdisc_dev(q); | |
299 | struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0); | |
300 | ||
301 | if (slave_txq->qdisc_sleeping != q) | |
302 | continue; | |
303 | if (netif_xmit_stopped(netdev_get_tx_queue(slave, subq)) || | |
304 | !netif_running(slave)) { | |
305 | busy = 1; | |
306 | continue; | |
307 | } | |
308 | ||
309 | switch (teql_resolve(skb, skb_res, slave, slave_txq)) { | |
310 | case 0: | |
311 | if (__netif_tx_trylock(slave_txq)) { | |
312 | unsigned int length = qdisc_pkt_len(skb); | |
313 | ||
314 | if (!netif_xmit_frozen_or_stopped(slave_txq) && | |
315 | netdev_start_xmit(skb, slave, slave_txq, false) == | |
316 | NETDEV_TX_OK) { | |
317 | __netif_tx_unlock(slave_txq); | |
318 | master->slaves = NEXT_SLAVE(q); | |
319 | netif_wake_queue(dev); | |
320 | master->tx_packets++; | |
321 | master->tx_bytes += length; | |
322 | return NETDEV_TX_OK; | |
323 | } | |
324 | __netif_tx_unlock(slave_txq); | |
325 | } | |
326 | if (netif_xmit_stopped(netdev_get_tx_queue(dev, 0))) | |
327 | busy = 1; | |
328 | break; | |
329 | case 1: | |
330 | master->slaves = NEXT_SLAVE(q); | |
331 | return NETDEV_TX_OK; | |
332 | default: | |
333 | nores = 1; | |
334 | break; | |
335 | } | |
336 | __skb_pull(skb, skb_network_offset(skb)); | |
337 | } while ((q = NEXT_SLAVE(q)) != start); | |
338 | ||
339 | if (nores && skb_res == NULL) { | |
340 | skb_res = skb; | |
341 | goto restart; | |
342 | } | |
343 | ||
344 | if (busy) { | |
345 | netif_stop_queue(dev); | |
346 | return NETDEV_TX_BUSY; | |
347 | } | |
348 | master->tx_errors++; | |
349 | ||
350 | drop: | |
351 | master->tx_dropped++; | |
352 | dev_kfree_skb(skb); | |
353 | return NETDEV_TX_OK; | |
354 | } | |
355 | ||
356 | static int teql_master_open(struct net_device *dev) | |
357 | { | |
358 | struct Qdisc *q; | |
359 | struct teql_master *m = netdev_priv(dev); | |
360 | int mtu = 0xFFFE; | |
361 | unsigned int flags = IFF_NOARP | IFF_MULTICAST; | |
362 | ||
363 | if (m->slaves == NULL) | |
364 | return -EUNATCH; | |
365 | ||
366 | flags = FMASK; | |
367 | ||
368 | q = m->slaves; | |
369 | do { | |
370 | struct net_device *slave = qdisc_dev(q); | |
371 | ||
372 | if (slave == NULL) | |
373 | return -EUNATCH; | |
374 | ||
375 | if (slave->mtu < mtu) | |
376 | mtu = slave->mtu; | |
377 | if (slave->hard_header_len > LL_MAX_HEADER) | |
378 | return -EINVAL; | |
379 | ||
380 | /* If all the slaves are BROADCAST, master is BROADCAST | |
381 | If all the slaves are PtP, master is PtP | |
382 | Otherwise, master is NBMA. | |
383 | */ | |
384 | if (!(slave->flags&IFF_POINTOPOINT)) | |
385 | flags &= ~IFF_POINTOPOINT; | |
386 | if (!(slave->flags&IFF_BROADCAST)) | |
387 | flags &= ~IFF_BROADCAST; | |
388 | if (!(slave->flags&IFF_MULTICAST)) | |
389 | flags &= ~IFF_MULTICAST; | |
390 | } while ((q = NEXT_SLAVE(q)) != m->slaves); | |
391 | ||
392 | m->dev->mtu = mtu; | |
393 | m->dev->flags = (m->dev->flags&~FMASK) | flags; | |
394 | netif_start_queue(m->dev); | |
395 | return 0; | |
396 | } | |
397 | ||
398 | static int teql_master_close(struct net_device *dev) | |
399 | { | |
400 | netif_stop_queue(dev); | |
401 | return 0; | |
402 | } | |
403 | ||
404 | static struct rtnl_link_stats64 *teql_master_stats64(struct net_device *dev, | |
405 | struct rtnl_link_stats64 *stats) | |
406 | { | |
407 | struct teql_master *m = netdev_priv(dev); | |
408 | ||
409 | stats->tx_packets = m->tx_packets; | |
410 | stats->tx_bytes = m->tx_bytes; | |
411 | stats->tx_errors = m->tx_errors; | |
412 | stats->tx_dropped = m->tx_dropped; | |
413 | return stats; | |
414 | } | |
415 | ||
416 | static int teql_master_mtu(struct net_device *dev, int new_mtu) | |
417 | { | |
418 | struct teql_master *m = netdev_priv(dev); | |
419 | struct Qdisc *q; | |
420 | ||
421 | if (new_mtu < 68) | |
422 | return -EINVAL; | |
423 | ||
424 | q = m->slaves; | |
425 | if (q) { | |
426 | do { | |
427 | if (new_mtu > qdisc_dev(q)->mtu) | |
428 | return -EINVAL; | |
429 | } while ((q = NEXT_SLAVE(q)) != m->slaves); | |
430 | } | |
431 | ||
432 | dev->mtu = new_mtu; | |
433 | return 0; | |
434 | } | |
435 | ||
436 | static const struct net_device_ops teql_netdev_ops = { | |
437 | .ndo_open = teql_master_open, | |
438 | .ndo_stop = teql_master_close, | |
439 | .ndo_start_xmit = teql_master_xmit, | |
440 | .ndo_get_stats64 = teql_master_stats64, | |
441 | .ndo_change_mtu = teql_master_mtu, | |
442 | }; | |
443 | ||
444 | static __init void teql_master_setup(struct net_device *dev) | |
445 | { | |
446 | struct teql_master *master = netdev_priv(dev); | |
447 | struct Qdisc_ops *ops = &master->qops; | |
448 | ||
449 | master->dev = dev; | |
450 | ops->priv_size = sizeof(struct teql_sched_data); | |
451 | ||
452 | ops->enqueue = teql_enqueue; | |
453 | ops->dequeue = teql_dequeue; | |
454 | ops->peek = teql_peek; | |
455 | ops->init = teql_qdisc_init; | |
456 | ops->reset = teql_reset; | |
457 | ops->destroy = teql_destroy; | |
458 | ops->owner = THIS_MODULE; | |
459 | ||
460 | dev->netdev_ops = &teql_netdev_ops; | |
461 | dev->type = ARPHRD_VOID; | |
462 | dev->mtu = 1500; | |
463 | dev->tx_queue_len = 100; | |
464 | dev->flags = IFF_NOARP; | |
465 | dev->hard_header_len = LL_MAX_HEADER; | |
466 | netif_keep_dst(dev); | |
467 | } | |
468 | ||
469 | static LIST_HEAD(master_dev_list); | |
470 | static int max_equalizers = 1; | |
471 | module_param(max_equalizers, int, 0); | |
472 | MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers"); | |
473 | ||
474 | static int __init teql_init(void) | |
475 | { | |
476 | int i; | |
477 | int err = -ENODEV; | |
478 | ||
479 | for (i = 0; i < max_equalizers; i++) { | |
480 | struct net_device *dev; | |
481 | struct teql_master *master; | |
482 | ||
483 | dev = alloc_netdev(sizeof(struct teql_master), "teql%d", | |
484 | NET_NAME_UNKNOWN, teql_master_setup); | |
485 | if (!dev) { | |
486 | err = -ENOMEM; | |
487 | break; | |
488 | } | |
489 | ||
490 | if ((err = register_netdev(dev))) { | |
491 | free_netdev(dev); | |
492 | break; | |
493 | } | |
494 | ||
495 | master = netdev_priv(dev); | |
496 | ||
497 | strlcpy(master->qops.id, dev->name, IFNAMSIZ); | |
498 | err = register_qdisc(&master->qops); | |
499 | ||
500 | if (err) { | |
501 | unregister_netdev(dev); | |
502 | free_netdev(dev); | |
503 | break; | |
504 | } | |
505 | ||
506 | list_add_tail(&master->master_list, &master_dev_list); | |
507 | } | |
508 | return i ? 0 : err; | |
509 | } | |
510 | ||
511 | static void __exit teql_exit(void) | |
512 | { | |
513 | struct teql_master *master, *nxt; | |
514 | ||
515 | list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) { | |
516 | ||
517 | list_del(&master->master_list); | |
518 | ||
519 | unregister_qdisc(&master->qops); | |
520 | unregister_netdev(master->dev); | |
521 | free_netdev(master->dev); | |
522 | } | |
523 | } | |
524 | ||
525 | module_init(teql_init); | |
526 | module_exit(teql_exit); | |
527 | ||
528 | MODULE_LICENSE("GPL"); |