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|IFF_BROADCAST) 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 = sch->dev; 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 += skb->len; 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 int 97 teql_requeue(struct sk_buff *skb, struct Qdisc* sch) 98 { 99 struct teql_sched_data *q = qdisc_priv(sch); 100 101 __skb_queue_head(&q->q, skb); 102 sch->qstats.requeues++; 103 return 0; 104 } 105 106 static struct sk_buff * 107 teql_dequeue(struct Qdisc* sch) 108 { 109 struct teql_sched_data *dat = qdisc_priv(sch); 110 struct sk_buff *skb; 111 112 skb = __skb_dequeue(&dat->q); 113 if (skb == NULL) { 114 struct net_device *m = dat->m->dev->qdisc->dev; 115 if (m) { 116 dat->m->slaves = sch; 117 netif_wake_queue(m); 118 } 119 } 120 sch->q.qlen = dat->q.qlen + dat->m->dev->qdisc->q.qlen; 121 return skb; 122 } 123 124 static __inline__ void 125 teql_neigh_release(struct neighbour *n) 126 { 127 if (n) 128 neigh_release(n); 129 } 130 131 static void 132 teql_reset(struct Qdisc* sch) 133 { 134 struct teql_sched_data *dat = qdisc_priv(sch); 135 136 skb_queue_purge(&dat->q); 137 sch->q.qlen = 0; 138 teql_neigh_release(xchg(&dat->ncache, NULL)); 139 } 140 141 static void 142 teql_destroy(struct Qdisc* sch) 143 { 144 struct Qdisc *q, *prev; 145 struct teql_sched_data *dat = qdisc_priv(sch); 146 struct teql_master *master = dat->m; 147 148 if ((prev = master->slaves) != NULL) { 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 master->slaves = NULL; 157 spin_lock_bh(&master->dev->queue_lock); 158 qdisc_reset(master->dev->qdisc); 159 spin_unlock_bh(&master->dev->queue_lock); 160 } 161 } 162 skb_queue_purge(&dat->q); 163 teql_neigh_release(xchg(&dat->ncache, NULL)); 164 break; 165 } 166 167 } while ((prev = q) != master->slaves); 168 } 169 } 170 171 static int teql_qdisc_init(struct Qdisc *sch, struct rtattr *opt) 172 { 173 struct net_device *dev = sch->dev; 174 struct teql_master *m = (struct teql_master*)sch->ops; 175 struct teql_sched_data *q = qdisc_priv(sch); 176 177 if (dev->hard_header_len > m->dev->hard_header_len) 178 return -EINVAL; 179 180 if (m->dev == dev) 181 return -ELOOP; 182 183 q->m = m; 184 185 skb_queue_head_init(&q->q); 186 187 if (m->slaves) { 188 if (m->dev->flags & IFF_UP) { 189 if ((m->dev->flags&IFF_POINTOPOINT && !(dev->flags&IFF_POINTOPOINT)) 190 || (m->dev->flags&IFF_BROADCAST && !(dev->flags&IFF_BROADCAST)) 191 || (m->dev->flags&IFF_MULTICAST && !(dev->flags&IFF_MULTICAST)) 192 || dev->mtu < m->dev->mtu) 193 return -EINVAL; 194 } else { 195 if (!(dev->flags&IFF_POINTOPOINT)) 196 m->dev->flags &= ~IFF_POINTOPOINT; 197 if (!(dev->flags&IFF_BROADCAST)) 198 m->dev->flags &= ~IFF_BROADCAST; 199 if (!(dev->flags&IFF_MULTICAST)) 200 m->dev->flags &= ~IFF_MULTICAST; 201 if (dev->mtu < m->dev->mtu) 202 m->dev->mtu = dev->mtu; 203 } 204 q->next = NEXT_SLAVE(m->slaves); 205 NEXT_SLAVE(m->slaves) = sch; 206 } else { 207 q->next = sch; 208 m->slaves = sch; 209 m->dev->mtu = dev->mtu; 210 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK); 211 } 212 return 0; 213 } 214 215 216 static int 217 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev) 218 { 219 struct teql_sched_data *q = qdisc_priv(dev->qdisc); 220 struct neighbour *mn = skb->dst->neighbour; 221 struct neighbour *n = q->ncache; 222 223 if (mn->tbl == NULL) 224 return -EINVAL; 225 if (n && n->tbl == mn->tbl && 226 memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) { 227 atomic_inc(&n->refcnt); 228 } else { 229 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev); 230 if (IS_ERR(n)) 231 return PTR_ERR(n); 232 } 233 if (neigh_event_send(n, skb_res) == 0) { 234 int err; 235 236 read_lock(&n->lock); 237 err = dev_hard_header(skb, dev, ntohs(skb->protocol), 238 n->ha, NULL, skb->len); 239 read_unlock(&n->lock); 240 241 if (err < 0) { 242 neigh_release(n); 243 return -EINVAL; 244 } 245 teql_neigh_release(xchg(&q->ncache, n)); 246 return 0; 247 } 248 neigh_release(n); 249 return (skb_res == NULL) ? -EAGAIN : 1; 250 } 251 252 static inline int teql_resolve(struct sk_buff *skb, 253 struct sk_buff *skb_res, struct net_device *dev) 254 { 255 if (dev->header_ops == NULL || 256 skb->dst == NULL || 257 skb->dst->neighbour == NULL) 258 return 0; 259 return __teql_resolve(skb, skb_res, dev); 260 } 261 262 static int teql_master_xmit(struct sk_buff *skb, struct net_device *dev) 263 { 264 struct teql_master *master = netdev_priv(dev); 265 struct Qdisc *start, *q; 266 int busy; 267 int nores; 268 int len = skb->len; 269 int subq = skb->queue_mapping; 270 struct sk_buff *skb_res = NULL; 271 272 start = master->slaves; 273 274 restart: 275 nores = 0; 276 busy = 0; 277 278 if ((q = start) == NULL) 279 goto drop; 280 281 do { 282 struct net_device *slave = q->dev; 283 284 if (slave->qdisc_sleeping != q) 285 continue; 286 if (netif_queue_stopped(slave) || 287 netif_subqueue_stopped(slave, subq) || 288 !netif_running(slave)) { 289 busy = 1; 290 continue; 291 } 292 293 switch (teql_resolve(skb, skb_res, slave)) { 294 case 0: 295 if (netif_tx_trylock(slave)) { 296 if (!netif_queue_stopped(slave) && 297 !netif_subqueue_stopped(slave, subq) && 298 slave->hard_start_xmit(skb, slave) == 0) { 299 netif_tx_unlock(slave); 300 master->slaves = NEXT_SLAVE(q); 301 netif_wake_queue(dev); 302 master->stats.tx_packets++; 303 master->stats.tx_bytes += len; 304 return 0; 305 } 306 netif_tx_unlock(slave); 307 } 308 if (netif_queue_stopped(dev)) 309 busy = 1; 310 break; 311 case 1: 312 master->slaves = NEXT_SLAVE(q); 313 return 0; 314 default: 315 nores = 1; 316 break; 317 } 318 __skb_pull(skb, skb_network_offset(skb)); 319 } while ((q = NEXT_SLAVE(q)) != start); 320 321 if (nores && skb_res == NULL) { 322 skb_res = skb; 323 goto restart; 324 } 325 326 if (busy) { 327 netif_stop_queue(dev); 328 return 1; 329 } 330 master->stats.tx_errors++; 331 332 drop: 333 master->stats.tx_dropped++; 334 dev_kfree_skb(skb); 335 return 0; 336 } 337 338 static int teql_master_open(struct net_device *dev) 339 { 340 struct Qdisc * q; 341 struct teql_master *m = netdev_priv(dev); 342 int mtu = 0xFFFE; 343 unsigned flags = IFF_NOARP|IFF_MULTICAST; 344 345 if (m->slaves == NULL) 346 return -EUNATCH; 347 348 flags = FMASK; 349 350 q = m->slaves; 351 do { 352 struct net_device *slave = q->dev; 353 354 if (slave == NULL) 355 return -EUNATCH; 356 357 if (slave->mtu < mtu) 358 mtu = slave->mtu; 359 if (slave->hard_header_len > LL_MAX_HEADER) 360 return -EINVAL; 361 362 /* If all the slaves are BROADCAST, master is BROADCAST 363 If all the slaves are PtP, master is PtP 364 Otherwise, master is NBMA. 365 */ 366 if (!(slave->flags&IFF_POINTOPOINT)) 367 flags &= ~IFF_POINTOPOINT; 368 if (!(slave->flags&IFF_BROADCAST)) 369 flags &= ~IFF_BROADCAST; 370 if (!(slave->flags&IFF_MULTICAST)) 371 flags &= ~IFF_MULTICAST; 372 } while ((q = NEXT_SLAVE(q)) != m->slaves); 373 374 m->dev->mtu = mtu; 375 m->dev->flags = (m->dev->flags&~FMASK) | flags; 376 netif_start_queue(m->dev); 377 return 0; 378 } 379 380 static int teql_master_close(struct net_device *dev) 381 { 382 netif_stop_queue(dev); 383 return 0; 384 } 385 386 static struct net_device_stats *teql_master_stats(struct net_device *dev) 387 { 388 struct teql_master *m = netdev_priv(dev); 389 return &m->stats; 390 } 391 392 static int teql_master_mtu(struct net_device *dev, int new_mtu) 393 { 394 struct teql_master *m = netdev_priv(dev); 395 struct Qdisc *q; 396 397 if (new_mtu < 68) 398 return -EINVAL; 399 400 q = m->slaves; 401 if (q) { 402 do { 403 if (new_mtu > q->dev->mtu) 404 return -EINVAL; 405 } while ((q=NEXT_SLAVE(q)) != m->slaves); 406 } 407 408 dev->mtu = new_mtu; 409 return 0; 410 } 411 412 static __init void teql_master_setup(struct net_device *dev) 413 { 414 struct teql_master *master = netdev_priv(dev); 415 struct Qdisc_ops *ops = &master->qops; 416 417 master->dev = dev; 418 ops->priv_size = sizeof(struct teql_sched_data); 419 420 ops->enqueue = teql_enqueue; 421 ops->dequeue = teql_dequeue; 422 ops->requeue = teql_requeue; 423 ops->init = teql_qdisc_init; 424 ops->reset = teql_reset; 425 ops->destroy = teql_destroy; 426 ops->owner = THIS_MODULE; 427 428 dev->open = teql_master_open; 429 dev->hard_start_xmit = teql_master_xmit; 430 dev->stop = teql_master_close; 431 dev->get_stats = teql_master_stats; 432 dev->change_mtu = teql_master_mtu; 433 dev->type = ARPHRD_VOID; 434 dev->mtu = 1500; 435 dev->tx_queue_len = 100; 436 dev->flags = IFF_NOARP; 437 dev->hard_header_len = LL_MAX_HEADER; 438 } 439 440 static LIST_HEAD(master_dev_list); 441 static int max_equalizers = 1; 442 module_param(max_equalizers, int, 0); 443 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers"); 444 445 static int __init teql_init(void) 446 { 447 int i; 448 int err = -ENODEV; 449 450 for (i = 0; i < max_equalizers; i++) { 451 struct net_device *dev; 452 struct teql_master *master; 453 454 dev = alloc_netdev(sizeof(struct teql_master), 455 "teql%d", teql_master_setup); 456 if (!dev) { 457 err = -ENOMEM; 458 break; 459 } 460 461 if ((err = register_netdev(dev))) { 462 free_netdev(dev); 463 break; 464 } 465 466 master = netdev_priv(dev); 467 468 strlcpy(master->qops.id, dev->name, IFNAMSIZ); 469 err = register_qdisc(&master->qops); 470 471 if (err) { 472 unregister_netdev(dev); 473 free_netdev(dev); 474 break; 475 } 476 477 list_add_tail(&master->master_list, &master_dev_list); 478 } 479 return i ? 0 : err; 480 } 481 482 static void __exit teql_exit(void) 483 { 484 struct teql_master *master, *nxt; 485 486 list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) { 487 488 list_del(&master->master_list); 489 490 unregister_qdisc(&master->qops); 491 unregister_netdev(master->dev); 492 free_netdev(master->dev); 493 } 494 } 495 496 module_init(teql_init); 497 module_exit(teql_exit); 498 499 MODULE_LICENSE("GPL"); 500