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/string.h> 15 #include <linux/errno.h> 16 #include <linux/if_arp.h> 17 #include <linux/netdevice.h> 18 #include <linux/init.h> 19 #include <linux/skbuff.h> 20 #include <linux/moduleparam.h> 21 #include <net/dst.h> 22 #include <net/neighbour.h> 23 #include <net/pkt_sched.h> 24 25 /* 26 How to setup it. 27 ---------------- 28 29 After loading this module you will find a new device teqlN 30 and new qdisc with the same name. To join a slave to the equalizer 31 you should just set this qdisc on a device f.e. 32 33 # tc qdisc add dev eth0 root teql0 34 # tc qdisc add dev eth1 root teql0 35 36 That's all. Full PnP 8) 37 38 Applicability. 39 -------------- 40 41 1. Slave devices MUST be active devices, i.e., they must raise the tbusy 42 signal and generate EOI events. If you want to equalize virtual devices 43 like tunnels, use a normal eql device. 44 2. This device puts no limitations on physical slave characteristics 45 f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-) 46 Certainly, large difference in link speeds will make the resulting 47 eqalized link unusable, because of huge packet reordering. 48 I estimate an upper useful difference as ~10 times. 49 3. If the slave requires address resolution, only protocols using 50 neighbour cache (IPv4/IPv6) will work over the equalized link. 51 Other protocols are still allowed to use the slave device directly, 52 which will not break load balancing, though native slave 53 traffic will have the highest priority. */ 54 55 struct teql_master 56 { 57 struct Qdisc_ops qops; 58 struct net_device *dev; 59 struct Qdisc *slaves; 60 struct list_head master_list; 61 struct net_device_stats stats; 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 0; 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 && !(dev->flags&IFF_POINTOPOINT)) 195 || (m->dev->flags&IFF_BROADCAST && !(dev->flags&IFF_BROADCAST)) 196 || (m->dev->flags&IFF_MULTICAST && !(dev->flags&IFF_MULTICAST)) 197 || dev->mtu < m->dev->mtu) 198 return -EINVAL; 199 } else { 200 if (!(dev->flags&IFF_POINTOPOINT)) 201 m->dev->flags &= ~IFF_POINTOPOINT; 202 if (!(dev->flags&IFF_BROADCAST)) 203 m->dev->flags &= ~IFF_BROADCAST; 204 if (!(dev->flags&IFF_MULTICAST)) 205 m->dev->flags &= ~IFF_MULTICAST; 206 if (dev->mtu < m->dev->mtu) 207 m->dev->mtu = dev->mtu; 208 } 209 q->next = NEXT_SLAVE(m->slaves); 210 NEXT_SLAVE(m->slaves) = sch; 211 } else { 212 q->next = sch; 213 m->slaves = sch; 214 m->dev->mtu = dev->mtu; 215 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK); 216 } 217 return 0; 218 } 219 220 221 static int 222 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev) 223 { 224 struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, 0); 225 struct teql_sched_data *q = qdisc_priv(dev_queue->qdisc); 226 struct neighbour *mn = skb->dst->neighbour; 227 struct neighbour *n = q->ncache; 228 229 if (mn->tbl == NULL) 230 return -EINVAL; 231 if (n && n->tbl == mn->tbl && 232 memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) { 233 atomic_inc(&n->refcnt); 234 } else { 235 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev); 236 if (IS_ERR(n)) 237 return PTR_ERR(n); 238 } 239 if (neigh_event_send(n, skb_res) == 0) { 240 int err; 241 242 read_lock(&n->lock); 243 err = dev_hard_header(skb, dev, ntohs(skb->protocol), 244 n->ha, NULL, skb->len); 245 read_unlock(&n->lock); 246 247 if (err < 0) { 248 neigh_release(n); 249 return -EINVAL; 250 } 251 teql_neigh_release(xchg(&q->ncache, n)); 252 return 0; 253 } 254 neigh_release(n); 255 return (skb_res == NULL) ? -EAGAIN : 1; 256 } 257 258 static inline int teql_resolve(struct sk_buff *skb, 259 struct sk_buff *skb_res, struct net_device *dev) 260 { 261 struct netdev_queue *txq = netdev_get_tx_queue(dev, 0); 262 if (txq->qdisc == &noop_qdisc) 263 return -ENODEV; 264 265 if (dev->header_ops == NULL || 266 skb->dst == NULL || 267 skb->dst->neighbour == NULL) 268 return 0; 269 return __teql_resolve(skb, skb_res, dev); 270 } 271 272 static int teql_master_xmit(struct sk_buff *skb, struct net_device *dev) 273 { 274 struct teql_master *master = netdev_priv(dev); 275 struct Qdisc *start, *q; 276 int busy; 277 int nores; 278 int subq = skb_get_queue_mapping(skb); 279 struct sk_buff *skb_res = NULL; 280 281 start = master->slaves; 282 283 restart: 284 nores = 0; 285 busy = 0; 286 287 if ((q = start) == NULL) 288 goto drop; 289 290 do { 291 struct net_device *slave = qdisc_dev(q); 292 struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0); 293 const struct net_device_ops *slave_ops = slave->netdev_ops; 294 295 if (slave_txq->qdisc_sleeping != q) 296 continue; 297 if (__netif_subqueue_stopped(slave, subq) || 298 !netif_running(slave)) { 299 busy = 1; 300 continue; 301 } 302 303 switch (teql_resolve(skb, skb_res, slave)) { 304 case 0: 305 if (__netif_tx_trylock(slave_txq)) { 306 if (!netif_tx_queue_stopped(slave_txq) && 307 !netif_tx_queue_frozen(slave_txq) && 308 slave_ops->ndo_start_xmit(skb, slave) == 0) { 309 __netif_tx_unlock(slave_txq); 310 master->slaves = NEXT_SLAVE(q); 311 netif_wake_queue(dev); 312 master->stats.tx_packets++; 313 master->stats.tx_bytes += 314 qdisc_pkt_len(skb); 315 return 0; 316 } 317 __netif_tx_unlock(slave_txq); 318 } 319 if (netif_queue_stopped(dev)) 320 busy = 1; 321 break; 322 case 1: 323 master->slaves = NEXT_SLAVE(q); 324 return 0; 325 default: 326 nores = 1; 327 break; 328 } 329 __skb_pull(skb, skb_network_offset(skb)); 330 } while ((q = NEXT_SLAVE(q)) != start); 331 332 if (nores && skb_res == NULL) { 333 skb_res = skb; 334 goto restart; 335 } 336 337 if (busy) { 338 netif_stop_queue(dev); 339 return 1; 340 } 341 master->stats.tx_errors++; 342 343 drop: 344 master->stats.tx_dropped++; 345 dev_kfree_skb(skb); 346 return 0; 347 } 348 349 static int teql_master_open(struct net_device *dev) 350 { 351 struct Qdisc * q; 352 struct teql_master *m = netdev_priv(dev); 353 int mtu = 0xFFFE; 354 unsigned flags = IFF_NOARP|IFF_MULTICAST; 355 356 if (m->slaves == NULL) 357 return -EUNATCH; 358 359 flags = FMASK; 360 361 q = m->slaves; 362 do { 363 struct net_device *slave = qdisc_dev(q); 364 365 if (slave == NULL) 366 return -EUNATCH; 367 368 if (slave->mtu < mtu) 369 mtu = slave->mtu; 370 if (slave->hard_header_len > LL_MAX_HEADER) 371 return -EINVAL; 372 373 /* If all the slaves are BROADCAST, master is BROADCAST 374 If all the slaves are PtP, master is PtP 375 Otherwise, master is NBMA. 376 */ 377 if (!(slave->flags&IFF_POINTOPOINT)) 378 flags &= ~IFF_POINTOPOINT; 379 if (!(slave->flags&IFF_BROADCAST)) 380 flags &= ~IFF_BROADCAST; 381 if (!(slave->flags&IFF_MULTICAST)) 382 flags &= ~IFF_MULTICAST; 383 } while ((q = NEXT_SLAVE(q)) != m->slaves); 384 385 m->dev->mtu = mtu; 386 m->dev->flags = (m->dev->flags&~FMASK) | flags; 387 netif_start_queue(m->dev); 388 return 0; 389 } 390 391 static int teql_master_close(struct net_device *dev) 392 { 393 netif_stop_queue(dev); 394 return 0; 395 } 396 397 static struct net_device_stats *teql_master_stats(struct net_device *dev) 398 { 399 struct teql_master *m = netdev_priv(dev); 400 return &m->stats; 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_get_stats = teql_master_stats, 428 .ndo_change_mtu = teql_master_mtu, 429 }; 430 431 static __init void teql_master_setup(struct net_device *dev) 432 { 433 struct teql_master *master = netdev_priv(dev); 434 struct Qdisc_ops *ops = &master->qops; 435 436 master->dev = dev; 437 ops->priv_size = sizeof(struct teql_sched_data); 438 439 ops->enqueue = teql_enqueue; 440 ops->dequeue = teql_dequeue; 441 ops->peek = teql_peek; 442 ops->init = teql_qdisc_init; 443 ops->reset = teql_reset; 444 ops->destroy = teql_destroy; 445 ops->owner = THIS_MODULE; 446 447 dev->netdev_ops = &teql_netdev_ops; 448 dev->type = ARPHRD_VOID; 449 dev->mtu = 1500; 450 dev->tx_queue_len = 100; 451 dev->flags = IFF_NOARP; 452 dev->hard_header_len = LL_MAX_HEADER; 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"); 515