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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
56struct 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
67struct teql_sched_data {
68 struct Qdisc *next;
69 struct teql_master *m;
70 struct neighbour *ncache;
71 struct sk_buff_head q;
72};
73
74#define NEXT_SLAVE(q) (((struct teql_sched_data *)qdisc_priv(q))->next)
75
76#define FMASK (IFF_BROADCAST | IFF_POINTOPOINT)
77
78/* "teql*" qdisc routines */
79
80static int
81teql_enqueue(struct sk_buff *skb, struct Qdisc *sch)
82{
83 struct net_device *dev = qdisc_dev(sch);
84 struct teql_sched_data *q = qdisc_priv(sch);
85
86 if (q->q.qlen < dev->tx_queue_len) {
87 __skb_queue_tail(&q->q, skb);
88 return NET_XMIT_SUCCESS;
89 }
90
91 return qdisc_drop(skb, sch);
92}
93
94static struct sk_buff *
95teql_dequeue(struct Qdisc *sch)
96{
97 struct teql_sched_data *dat = qdisc_priv(sch);
98 struct netdev_queue *dat_queue;
99 struct sk_buff *skb;
100
101 skb = __skb_dequeue(&dat->q);
102 dat_queue = netdev_get_tx_queue(dat->m->dev, 0);
103 if (skb == NULL) {
104 struct net_device *m = qdisc_dev(dat_queue->qdisc);
105 if (m) {
106 dat->m->slaves = sch;
107 netif_wake_queue(m);
108 }
109 } else {
110 qdisc_bstats_update(sch, skb);
111 }
112 sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen;
113 return skb;
114}
115
116static struct sk_buff *
117teql_peek(struct Qdisc *sch)
118{
119 /* teql is meant to be used as root qdisc */
120 return NULL;
121}
122
123static inline void
124teql_neigh_release(struct neighbour *n)
125{
126 if (n)
127 neigh_release(n);
128}
129
130static void
131teql_reset(struct Qdisc *sch)
132{
133 struct teql_sched_data *dat = qdisc_priv(sch);
134
135 skb_queue_purge(&dat->q);
136 sch->q.qlen = 0;
137 teql_neigh_release(xchg(&dat->ncache, NULL));
138}
139
140static void
141teql_destroy(struct Qdisc *sch)
142{
143 struct Qdisc *q, *prev;
144 struct teql_sched_data *dat = qdisc_priv(sch);
145 struct teql_master *master = dat->m;
146
147 prev = master->slaves;
148 if (prev) {
149 do {
150 q = NEXT_SLAVE(prev);
151 if (q == sch) {
152 NEXT_SLAVE(prev) = NEXT_SLAVE(q);
153 if (q == master->slaves) {
154 master->slaves = NEXT_SLAVE(q);
155 if (q == master->slaves) {
156 struct netdev_queue *txq;
157 spinlock_t *root_lock;
158
159 txq = netdev_get_tx_queue(master->dev, 0);
160 master->slaves = NULL;
161
162 root_lock = qdisc_root_sleeping_lock(txq->qdisc);
163 spin_lock_bh(root_lock);
164 qdisc_reset(txq->qdisc);
165 spin_unlock_bh(root_lock);
166 }
167 }
168 skb_queue_purge(&dat->q);
169 teql_neigh_release(xchg(&dat->ncache, NULL));
170 break;
171 }
172
173 } while ((prev = q) != master->slaves);
174 }
175}
176
177static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt)
178{
179 struct net_device *dev = qdisc_dev(sch);
180 struct teql_master *m = (struct teql_master *)sch->ops;
181 struct teql_sched_data *q = qdisc_priv(sch);
182
183 if (dev->hard_header_len > m->dev->hard_header_len)
184 return -EINVAL;
185
186 if (m->dev == dev)
187 return -ELOOP;
188
189 q->m = m;
190
191 skb_queue_head_init(&q->q);
192
193 if (m->slaves) {
194 if (m->dev->flags & IFF_UP) {
195 if ((m->dev->flags & IFF_POINTOPOINT &&
196 !(dev->flags & IFF_POINTOPOINT)) ||
197 (m->dev->flags & IFF_BROADCAST &&
198 !(dev->flags & IFF_BROADCAST)) ||
199 (m->dev->flags & IFF_MULTICAST &&
200 !(dev->flags & IFF_MULTICAST)) ||
201 dev->mtu < m->dev->mtu)
202 return -EINVAL;
203 } else {
204 if (!(dev->flags&IFF_POINTOPOINT))
205 m->dev->flags &= ~IFF_POINTOPOINT;
206 if (!(dev->flags&IFF_BROADCAST))
207 m->dev->flags &= ~IFF_BROADCAST;
208 if (!(dev->flags&IFF_MULTICAST))
209 m->dev->flags &= ~IFF_MULTICAST;
210 if (dev->mtu < m->dev->mtu)
211 m->dev->mtu = dev->mtu;
212 }
213 q->next = NEXT_SLAVE(m->slaves);
214 NEXT_SLAVE(m->slaves) = sch;
215 } else {
216 q->next = sch;
217 m->slaves = sch;
218 m->dev->mtu = dev->mtu;
219 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK);
220 }
221 return 0;
222}
223
224
225static int
226__teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res,
227 struct net_device *dev, struct netdev_queue *txq,
228 struct neighbour *mn)
229{
230 struct teql_sched_data *q = qdisc_priv(txq->qdisc);
231 struct neighbour *n = q->ncache;
232
233 if (mn->tbl == NULL)
234 return -EINVAL;
235 if (n && n->tbl == mn->tbl &&
236 memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) {
237 atomic_inc(&n->refcnt);
238 } else {
239 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev);
240 if (IS_ERR(n))
241 return PTR_ERR(n);
242 }
243 if (neigh_event_send(n, skb_res) == 0) {
244 int err;
245 char haddr[MAX_ADDR_LEN];
246
247 neigh_ha_snapshot(haddr, n, dev);
248 err = dev_hard_header(skb, dev, ntohs(skb->protocol), haddr,
249 NULL, skb->len);
250
251 if (err < 0) {
252 neigh_release(n);
253 return -EINVAL;
254 }
255 teql_neigh_release(xchg(&q->ncache, n));
256 return 0;
257 }
258 neigh_release(n);
259 return (skb_res == NULL) ? -EAGAIN : 1;
260}
261
262static inline int teql_resolve(struct sk_buff *skb,
263 struct sk_buff *skb_res,
264 struct net_device *dev,
265 struct netdev_queue *txq)
266{
267 struct dst_entry *dst = skb_dst(skb);
268 struct neighbour *mn;
269 int res;
270
271 if (txq->qdisc == &noop_qdisc)
272 return -ENODEV;
273
274 if (!dev->header_ops || !dst)
275 return 0;
276
277 rcu_read_lock();
278 mn = dst_get_neighbour_noref(dst);
279 res = mn ? __teql_resolve(skb, skb_res, dev, txq, mn) : 0;
280 rcu_read_unlock();
281
282 return res;
283}
284
285static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
286{
287 struct teql_master *master = netdev_priv(dev);
288 struct Qdisc *start, *q;
289 int busy;
290 int nores;
291 int subq = skb_get_queue_mapping(skb);
292 struct sk_buff *skb_res = NULL;
293
294 start = master->slaves;
295
296restart:
297 nores = 0;
298 busy = 0;
299
300 q = start;
301 if (!q)
302 goto drop;
303
304 do {
305 struct net_device *slave = qdisc_dev(q);
306 struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0);
307 const struct net_device_ops *slave_ops = slave->netdev_ops;
308
309 if (slave_txq->qdisc_sleeping != q)
310 continue;
311 if (netif_xmit_stopped(netdev_get_tx_queue(slave, subq)) ||
312 !netif_running(slave)) {
313 busy = 1;
314 continue;
315 }
316
317 switch (teql_resolve(skb, skb_res, slave, slave_txq)) {
318 case 0:
319 if (__netif_tx_trylock(slave_txq)) {
320 unsigned int length = qdisc_pkt_len(skb);
321
322 if (!netif_xmit_frozen_or_stopped(slave_txq) &&
323 slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) {
324 txq_trans_update(slave_txq);
325 __netif_tx_unlock(slave_txq);
326 master->slaves = NEXT_SLAVE(q);
327 netif_wake_queue(dev);
328 master->tx_packets++;
329 master->tx_bytes += length;
330 return NETDEV_TX_OK;
331 }
332 __netif_tx_unlock(slave_txq);
333 }
334 if (netif_xmit_stopped(netdev_get_tx_queue(dev, 0)))
335 busy = 1;
336 break;
337 case 1:
338 master->slaves = NEXT_SLAVE(q);
339 return NETDEV_TX_OK;
340 default:
341 nores = 1;
342 break;
343 }
344 __skb_pull(skb, skb_network_offset(skb));
345 } while ((q = NEXT_SLAVE(q)) != start);
346
347 if (nores && skb_res == NULL) {
348 skb_res = skb;
349 goto restart;
350 }
351
352 if (busy) {
353 netif_stop_queue(dev);
354 return NETDEV_TX_BUSY;
355 }
356 master->tx_errors++;
357
358drop:
359 master->tx_dropped++;
360 dev_kfree_skb(skb);
361 return NETDEV_TX_OK;
362}
363
364static int teql_master_open(struct net_device *dev)
365{
366 struct Qdisc *q;
367 struct teql_master *m = netdev_priv(dev);
368 int mtu = 0xFFFE;
369 unsigned int flags = IFF_NOARP | IFF_MULTICAST;
370
371 if (m->slaves == NULL)
372 return -EUNATCH;
373
374 flags = FMASK;
375
376 q = m->slaves;
377 do {
378 struct net_device *slave = qdisc_dev(q);
379
380 if (slave == NULL)
381 return -EUNATCH;
382
383 if (slave->mtu < mtu)
384 mtu = slave->mtu;
385 if (slave->hard_header_len > LL_MAX_HEADER)
386 return -EINVAL;
387
388 /* If all the slaves are BROADCAST, master is BROADCAST
389 If all the slaves are PtP, master is PtP
390 Otherwise, master is NBMA.
391 */
392 if (!(slave->flags&IFF_POINTOPOINT))
393 flags &= ~IFF_POINTOPOINT;
394 if (!(slave->flags&IFF_BROADCAST))
395 flags &= ~IFF_BROADCAST;
396 if (!(slave->flags&IFF_MULTICAST))
397 flags &= ~IFF_MULTICAST;
398 } while ((q = NEXT_SLAVE(q)) != m->slaves);
399
400 m->dev->mtu = mtu;
401 m->dev->flags = (m->dev->flags&~FMASK) | flags;
402 netif_start_queue(m->dev);
403 return 0;
404}
405
406static int teql_master_close(struct net_device *dev)
407{
408 netif_stop_queue(dev);
409 return 0;
410}
411
412static struct rtnl_link_stats64 *teql_master_stats64(struct net_device *dev,
413 struct rtnl_link_stats64 *stats)
414{
415 struct teql_master *m = netdev_priv(dev);
416
417 stats->tx_packets = m->tx_packets;
418 stats->tx_bytes = m->tx_bytes;
419 stats->tx_errors = m->tx_errors;
420 stats->tx_dropped = m->tx_dropped;
421 return stats;
422}
423
424static int teql_master_mtu(struct net_device *dev, int new_mtu)
425{
426 struct teql_master *m = netdev_priv(dev);
427 struct Qdisc *q;
428
429 if (new_mtu < 68)
430 return -EINVAL;
431
432 q = m->slaves;
433 if (q) {
434 do {
435 if (new_mtu > qdisc_dev(q)->mtu)
436 return -EINVAL;
437 } while ((q = NEXT_SLAVE(q)) != m->slaves);
438 }
439
440 dev->mtu = new_mtu;
441 return 0;
442}
443
444static const struct net_device_ops teql_netdev_ops = {
445 .ndo_open = teql_master_open,
446 .ndo_stop = teql_master_close,
447 .ndo_start_xmit = teql_master_xmit,
448 .ndo_get_stats64 = teql_master_stats64,
449 .ndo_change_mtu = teql_master_mtu,
450};
451
452static __init void teql_master_setup(struct net_device *dev)
453{
454 struct teql_master *master = netdev_priv(dev);
455 struct Qdisc_ops *ops = &master->qops;
456
457 master->dev = dev;
458 ops->priv_size = sizeof(struct teql_sched_data);
459
460 ops->enqueue = teql_enqueue;
461 ops->dequeue = teql_dequeue;
462 ops->peek = teql_peek;
463 ops->init = teql_qdisc_init;
464 ops->reset = teql_reset;
465 ops->destroy = teql_destroy;
466 ops->owner = THIS_MODULE;
467
468 dev->netdev_ops = &teql_netdev_ops;
469 dev->type = ARPHRD_VOID;
470 dev->mtu = 1500;
471 dev->tx_queue_len = 100;
472 dev->flags = IFF_NOARP;
473 dev->hard_header_len = LL_MAX_HEADER;
474 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
475}
476
477static LIST_HEAD(master_dev_list);
478static int max_equalizers = 1;
479module_param(max_equalizers, int, 0);
480MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers");
481
482static int __init teql_init(void)
483{
484 int i;
485 int err = -ENODEV;
486
487 for (i = 0; i < max_equalizers; i++) {
488 struct net_device *dev;
489 struct teql_master *master;
490
491 dev = alloc_netdev(sizeof(struct teql_master),
492 "teql%d", teql_master_setup);
493 if (!dev) {
494 err = -ENOMEM;
495 break;
496 }
497
498 if ((err = register_netdev(dev))) {
499 free_netdev(dev);
500 break;
501 }
502
503 master = netdev_priv(dev);
504
505 strlcpy(master->qops.id, dev->name, IFNAMSIZ);
506 err = register_qdisc(&master->qops);
507
508 if (err) {
509 unregister_netdev(dev);
510 free_netdev(dev);
511 break;
512 }
513
514 list_add_tail(&master->master_list, &master_dev_list);
515 }
516 return i ? 0 : err;
517}
518
519static void __exit teql_exit(void)
520{
521 struct teql_master *master, *nxt;
522
523 list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) {
524
525 list_del(&master->master_list);
526
527 unregister_qdisc(&master->qops);
528 unregister_netdev(master->dev);
529 free_netdev(master->dev);
530 }
531}
532
533module_init(teql_init);
534module_exit(teql_exit);
535
536MODULE_LICENSE("GPL");