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[mirror_ubuntu-bionic-kernel.git] / net / sched / sch_teql.c
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 {
58 struct Qdisc_ops qops;
59 struct net_device *dev;
60 struct Qdisc *slaves;
61 struct list_head master_list;
62 };
63
64 struct teql_sched_data
65 {
66 struct Qdisc *next;
67 struct teql_master *m;
68 struct neighbour *ncache;
69 struct sk_buff_head q;
70 };
71
72 #define NEXT_SLAVE(q) (((struct teql_sched_data*)qdisc_priv(q))->next)
73
74 #define FMASK (IFF_BROADCAST|IFF_POINTOPOINT)
75
76 /* "teql*" qdisc routines */
77
78 static int
79 teql_enqueue(struct sk_buff *skb, struct Qdisc* sch)
80 {
81 struct net_device *dev = qdisc_dev(sch);
82 struct teql_sched_data *q = qdisc_priv(sch);
83
84 if (q->q.qlen < dev->tx_queue_len) {
85 __skb_queue_tail(&q->q, skb);
86 sch->bstats.bytes += qdisc_pkt_len(skb);
87 sch->bstats.packets++;
88 return NET_XMIT_SUCCESS;
89 }
90
91 kfree_skb(skb);
92 sch->qstats.drops++;
93 return NET_XMIT_DROP;
94 }
95
96 static struct sk_buff *
97 teql_dequeue(struct Qdisc* sch)
98 {
99 struct teql_sched_data *dat = qdisc_priv(sch);
100 struct netdev_queue *dat_queue;
101 struct sk_buff *skb;
102
103 skb = __skb_dequeue(&dat->q);
104 dat_queue = netdev_get_tx_queue(dat->m->dev, 0);
105 if (skb == NULL) {
106 struct net_device *m = qdisc_dev(dat_queue->qdisc);
107 if (m) {
108 dat->m->slaves = sch;
109 netif_wake_queue(m);
110 }
111 }
112 sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen;
113 return skb;
114 }
115
116 static struct sk_buff *
117 teql_peek(struct Qdisc* sch)
118 {
119 /* teql is meant to be used as root qdisc */
120 return NULL;
121 }
122
123 static __inline__ void
124 teql_neigh_release(struct neighbour *n)
125 {
126 if (n)
127 neigh_release(n);
128 }
129
130 static void
131 teql_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
140 static void
141 teql_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 if ((prev = master->slaves) != NULL) {
148 do {
149 q = NEXT_SLAVE(prev);
150 if (q == sch) {
151 NEXT_SLAVE(prev) = NEXT_SLAVE(q);
152 if (q == master->slaves) {
153 master->slaves = NEXT_SLAVE(q);
154 if (q == master->slaves) {
155 struct netdev_queue *txq;
156 spinlock_t *root_lock;
157
158 txq = netdev_get_tx_queue(master->dev, 0);
159 master->slaves = NULL;
160
161 root_lock = qdisc_root_sleeping_lock(txq->qdisc);
162 spin_lock_bh(root_lock);
163 qdisc_reset(txq->qdisc);
164 spin_unlock_bh(root_lock);
165 }
166 }
167 skb_queue_purge(&dat->q);
168 teql_neigh_release(xchg(&dat->ncache, NULL));
169 break;
170 }
171
172 } while ((prev = q) != master->slaves);
173 }
174 }
175
176 static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt)
177 {
178 struct net_device *dev = qdisc_dev(sch);
179 struct teql_master *m = (struct teql_master*)sch->ops;
180 struct teql_sched_data *q = qdisc_priv(sch);
181
182 if (dev->hard_header_len > m->dev->hard_header_len)
183 return -EINVAL;
184
185 if (m->dev == dev)
186 return -ELOOP;
187
188 q->m = m;
189
190 skb_queue_head_init(&q->q);
191
192 if (m->slaves) {
193 if (m->dev->flags & IFF_UP) {
194 if ((m->dev->flags & IFF_POINTOPOINT &&
195 !(dev->flags & IFF_POINTOPOINT)) ||
196 (m->dev->flags & IFF_BROADCAST &&
197 !(dev->flags & IFF_BROADCAST)) ||
198 (m->dev->flags & IFF_MULTICAST &&
199 !(dev->flags & IFF_MULTICAST)) ||
200 dev->mtu < m->dev->mtu)
201 return -EINVAL;
202 } else {
203 if (!(dev->flags&IFF_POINTOPOINT))
204 m->dev->flags &= ~IFF_POINTOPOINT;
205 if (!(dev->flags&IFF_BROADCAST))
206 m->dev->flags &= ~IFF_BROADCAST;
207 if (!(dev->flags&IFF_MULTICAST))
208 m->dev->flags &= ~IFF_MULTICAST;
209 if (dev->mtu < m->dev->mtu)
210 m->dev->mtu = dev->mtu;
211 }
212 q->next = NEXT_SLAVE(m->slaves);
213 NEXT_SLAVE(m->slaves) = sch;
214 } else {
215 q->next = sch;
216 m->slaves = sch;
217 m->dev->mtu = dev->mtu;
218 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK);
219 }
220 return 0;
221 }
222
223
224 static int
225 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
226 {
227 struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, 0);
228 struct teql_sched_data *q = qdisc_priv(dev_queue->qdisc);
229 struct neighbour *mn = skb_dst(skb)->neighbour;
230 struct neighbour *n = q->ncache;
231
232 if (mn->tbl == NULL)
233 return -EINVAL;
234 if (n && n->tbl == mn->tbl &&
235 memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) {
236 atomic_inc(&n->refcnt);
237 } else {
238 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev);
239 if (IS_ERR(n))
240 return PTR_ERR(n);
241 }
242 if (neigh_event_send(n, skb_res) == 0) {
243 int err;
244 char haddr[MAX_ADDR_LEN];
245
246 neigh_ha_snapshot(haddr, n, dev);
247 err = dev_hard_header(skb, dev, ntohs(skb->protocol), haddr,
248 NULL, skb->len);
249
250 if (err < 0) {
251 neigh_release(n);
252 return -EINVAL;
253 }
254 teql_neigh_release(xchg(&q->ncache, n));
255 return 0;
256 }
257 neigh_release(n);
258 return (skb_res == NULL) ? -EAGAIN : 1;
259 }
260
261 static inline int teql_resolve(struct sk_buff *skb,
262 struct sk_buff *skb_res, struct net_device *dev)
263 {
264 struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
265 if (txq->qdisc == &noop_qdisc)
266 return -ENODEV;
267
268 if (dev->header_ops == NULL ||
269 skb_dst(skb) == NULL ||
270 skb_dst(skb)->neighbour == NULL)
271 return 0;
272 return __teql_resolve(skb, skb_res, dev);
273 }
274
275 static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
276 {
277 struct teql_master *master = netdev_priv(dev);
278 struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
279 struct Qdisc *start, *q;
280 int busy;
281 int nores;
282 int subq = skb_get_queue_mapping(skb);
283 struct sk_buff *skb_res = NULL;
284
285 start = master->slaves;
286
287 restart:
288 nores = 0;
289 busy = 0;
290
291 if ((q = start) == NULL)
292 goto drop;
293
294 do {
295 struct net_device *slave = qdisc_dev(q);
296 struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0);
297 const struct net_device_ops *slave_ops = slave->netdev_ops;
298
299 if (slave_txq->qdisc_sleeping != q)
300 continue;
301 if (__netif_subqueue_stopped(slave, subq) ||
302 !netif_running(slave)) {
303 busy = 1;
304 continue;
305 }
306
307 switch (teql_resolve(skb, skb_res, slave)) {
308 case 0:
309 if (__netif_tx_trylock(slave_txq)) {
310 unsigned int length = qdisc_pkt_len(skb);
311
312 if (!netif_tx_queue_stopped(slave_txq) &&
313 !netif_tx_queue_frozen(slave_txq) &&
314 slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) {
315 txq_trans_update(slave_txq);
316 __netif_tx_unlock(slave_txq);
317 master->slaves = NEXT_SLAVE(q);
318 netif_wake_queue(dev);
319 txq->tx_packets++;
320 txq->tx_bytes += length;
321 return NETDEV_TX_OK;
322 }
323 __netif_tx_unlock(slave_txq);
324 }
325 if (netif_queue_stopped(dev))
326 busy = 1;
327 break;
328 case 1:
329 master->slaves = NEXT_SLAVE(q);
330 return NETDEV_TX_OK;
331 default:
332 nores = 1;
333 break;
334 }
335 __skb_pull(skb, skb_network_offset(skb));
336 } while ((q = NEXT_SLAVE(q)) != start);
337
338 if (nores && skb_res == NULL) {
339 skb_res = skb;
340 goto restart;
341 }
342
343 if (busy) {
344 netif_stop_queue(dev);
345 return NETDEV_TX_BUSY;
346 }
347 dev->stats.tx_errors++;
348
349 drop:
350 txq->tx_dropped++;
351 dev_kfree_skb(skb);
352 return NETDEV_TX_OK;
353 }
354
355 static int teql_master_open(struct net_device *dev)
356 {
357 struct Qdisc * q;
358 struct teql_master *m = netdev_priv(dev);
359 int mtu = 0xFFFE;
360 unsigned flags = IFF_NOARP|IFF_MULTICAST;
361
362 if (m->slaves == NULL)
363 return -EUNATCH;
364
365 flags = FMASK;
366
367 q = m->slaves;
368 do {
369 struct net_device *slave = qdisc_dev(q);
370
371 if (slave == NULL)
372 return -EUNATCH;
373
374 if (slave->mtu < mtu)
375 mtu = slave->mtu;
376 if (slave->hard_header_len > LL_MAX_HEADER)
377 return -EINVAL;
378
379 /* If all the slaves are BROADCAST, master is BROADCAST
380 If all the slaves are PtP, master is PtP
381 Otherwise, master is NBMA.
382 */
383 if (!(slave->flags&IFF_POINTOPOINT))
384 flags &= ~IFF_POINTOPOINT;
385 if (!(slave->flags&IFF_BROADCAST))
386 flags &= ~IFF_BROADCAST;
387 if (!(slave->flags&IFF_MULTICAST))
388 flags &= ~IFF_MULTICAST;
389 } while ((q = NEXT_SLAVE(q)) != m->slaves);
390
391 m->dev->mtu = mtu;
392 m->dev->flags = (m->dev->flags&~FMASK) | flags;
393 netif_start_queue(m->dev);
394 return 0;
395 }
396
397 static int teql_master_close(struct net_device *dev)
398 {
399 netif_stop_queue(dev);
400 return 0;
401 }
402
403 static int teql_master_mtu(struct net_device *dev, int new_mtu)
404 {
405 struct teql_master *m = netdev_priv(dev);
406 struct Qdisc *q;
407
408 if (new_mtu < 68)
409 return -EINVAL;
410
411 q = m->slaves;
412 if (q) {
413 do {
414 if (new_mtu > qdisc_dev(q)->mtu)
415 return -EINVAL;
416 } while ((q=NEXT_SLAVE(q)) != m->slaves);
417 }
418
419 dev->mtu = new_mtu;
420 return 0;
421 }
422
423 static const struct net_device_ops teql_netdev_ops = {
424 .ndo_open = teql_master_open,
425 .ndo_stop = teql_master_close,
426 .ndo_start_xmit = teql_master_xmit,
427 .ndo_change_mtu = teql_master_mtu,
428 };
429
430 static __init void teql_master_setup(struct net_device *dev)
431 {
432 struct teql_master *master = netdev_priv(dev);
433 struct Qdisc_ops *ops = &master->qops;
434
435 master->dev = dev;
436 ops->priv_size = sizeof(struct teql_sched_data);
437
438 ops->enqueue = teql_enqueue;
439 ops->dequeue = teql_dequeue;
440 ops->peek = teql_peek;
441 ops->init = teql_qdisc_init;
442 ops->reset = teql_reset;
443 ops->destroy = teql_destroy;
444 ops->owner = THIS_MODULE;
445
446 dev->netdev_ops = &teql_netdev_ops;
447 dev->type = ARPHRD_VOID;
448 dev->mtu = 1500;
449 dev->tx_queue_len = 100;
450 dev->flags = IFF_NOARP;
451 dev->hard_header_len = LL_MAX_HEADER;
452 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
453 }
454
455 static LIST_HEAD(master_dev_list);
456 static int max_equalizers = 1;
457 module_param(max_equalizers, int, 0);
458 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers");
459
460 static int __init teql_init(void)
461 {
462 int i;
463 int err = -ENODEV;
464
465 for (i = 0; i < max_equalizers; i++) {
466 struct net_device *dev;
467 struct teql_master *master;
468
469 dev = alloc_netdev(sizeof(struct teql_master),
470 "teql%d", teql_master_setup);
471 if (!dev) {
472 err = -ENOMEM;
473 break;
474 }
475
476 if ((err = register_netdev(dev))) {
477 free_netdev(dev);
478 break;
479 }
480
481 master = netdev_priv(dev);
482
483 strlcpy(master->qops.id, dev->name, IFNAMSIZ);
484 err = register_qdisc(&master->qops);
485
486 if (err) {
487 unregister_netdev(dev);
488 free_netdev(dev);
489 break;
490 }
491
492 list_add_tail(&master->master_list, &master_dev_list);
493 }
494 return i ? 0 : err;
495 }
496
497 static void __exit teql_exit(void)
498 {
499 struct teql_master *master, *nxt;
500
501 list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) {
502
503 list_del(&master->master_list);
504
505 unregister_qdisc(&master->qops);
506 unregister_netdev(master->dev);
507 free_netdev(master->dev);
508 }
509 }
510
511 module_init(teql_init);
512 module_exit(teql_exit);
513
514 MODULE_LICENSE("GPL");
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