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 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 80 static int 81 teql_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 qdisc_bstats_update(sch, skb); 89 return NET_XMIT_SUCCESS; 90 } 91 92 kfree_skb(skb); 93 sch->qstats.drops++; 94 return NET_XMIT_DROP; 95 } 96 97 static struct sk_buff * 98 teql_dequeue(struct Qdisc *sch) 99 { 100 struct teql_sched_data *dat = qdisc_priv(sch); 101 struct netdev_queue *dat_queue; 102 struct sk_buff *skb; 103 104 skb = __skb_dequeue(&dat->q); 105 dat_queue = netdev_get_tx_queue(dat->m->dev, 0); 106 if (skb == NULL) { 107 struct net_device *m = qdisc_dev(dat_queue->qdisc); 108 if (m) { 109 dat->m->slaves = sch; 110 netif_wake_queue(m); 111 } 112 } 113 sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen; 114 return skb; 115 } 116 117 static struct sk_buff * 118 teql_peek(struct Qdisc *sch) 119 { 120 /* teql is meant to be used as root qdisc */ 121 return NULL; 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 prev = master->slaves; 149 if (prev) { 150 do { 151 q = NEXT_SLAVE(prev); 152 if (q == sch) { 153 NEXT_SLAVE(prev) = NEXT_SLAVE(q); 154 if (q == master->slaves) { 155 master->slaves = NEXT_SLAVE(q); 156 if (q == master->slaves) { 157 struct netdev_queue *txq; 158 spinlock_t *root_lock; 159 160 txq = netdev_get_tx_queue(master->dev, 0); 161 master->slaves = NULL; 162 163 root_lock = qdisc_root_sleeping_lock(txq->qdisc); 164 spin_lock_bh(root_lock); 165 qdisc_reset(txq->qdisc); 166 spin_unlock_bh(root_lock); 167 } 168 } 169 skb_queue_purge(&dat->q); 170 teql_neigh_release(xchg(&dat->ncache, NULL)); 171 break; 172 } 173 174 } while ((prev = q) != master->slaves); 175 } 176 } 177 178 static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt) 179 { 180 struct net_device *dev = qdisc_dev(sch); 181 struct teql_master *m = (struct teql_master *)sch->ops; 182 struct teql_sched_data *q = qdisc_priv(sch); 183 184 if (dev->hard_header_len > m->dev->hard_header_len) 185 return -EINVAL; 186 187 if (m->dev == dev) 188 return -ELOOP; 189 190 q->m = m; 191 192 skb_queue_head_init(&q->q); 193 194 if (m->slaves) { 195 if (m->dev->flags & IFF_UP) { 196 if ((m->dev->flags & IFF_POINTOPOINT && 197 !(dev->flags & IFF_POINTOPOINT)) || 198 (m->dev->flags & IFF_BROADCAST && 199 !(dev->flags & IFF_BROADCAST)) || 200 (m->dev->flags & IFF_MULTICAST && 201 !(dev->flags & IFF_MULTICAST)) || 202 dev->mtu < m->dev->mtu) 203 return -EINVAL; 204 } else { 205 if (!(dev->flags&IFF_POINTOPOINT)) 206 m->dev->flags &= ~IFF_POINTOPOINT; 207 if (!(dev->flags&IFF_BROADCAST)) 208 m->dev->flags &= ~IFF_BROADCAST; 209 if (!(dev->flags&IFF_MULTICAST)) 210 m->dev->flags &= ~IFF_MULTICAST; 211 if (dev->mtu < m->dev->mtu) 212 m->dev->mtu = dev->mtu; 213 } 214 q->next = NEXT_SLAVE(m->slaves); 215 NEXT_SLAVE(m->slaves) = sch; 216 } else { 217 q->next = sch; 218 m->slaves = sch; 219 m->dev->mtu = dev->mtu; 220 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK); 221 } 222 return 0; 223 } 224 225 226 static int 227 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev) 228 { 229 struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, 0); 230 struct teql_sched_data *q = qdisc_priv(dev_queue->qdisc); 231 struct neighbour *mn = skb_dst(skb)->neighbour; 232 struct neighbour *n = q->ncache; 233 234 if (mn->tbl == NULL) 235 return -EINVAL; 236 if (n && n->tbl == mn->tbl && 237 memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) { 238 atomic_inc(&n->refcnt); 239 } else { 240 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev); 241 if (IS_ERR(n)) 242 return PTR_ERR(n); 243 } 244 if (neigh_event_send(n, skb_res) == 0) { 245 int err; 246 char haddr[MAX_ADDR_LEN]; 247 248 neigh_ha_snapshot(haddr, n, dev); 249 err = dev_hard_header(skb, dev, ntohs(skb->protocol), haddr, 250 NULL, skb->len); 251 252 if (err < 0) { 253 neigh_release(n); 254 return -EINVAL; 255 } 256 teql_neigh_release(xchg(&q->ncache, n)); 257 return 0; 258 } 259 neigh_release(n); 260 return (skb_res == NULL) ? -EAGAIN : 1; 261 } 262 263 static inline int teql_resolve(struct sk_buff *skb, 264 struct sk_buff *skb_res, struct net_device *dev) 265 { 266 struct netdev_queue *txq = netdev_get_tx_queue(dev, 0); 267 if (txq->qdisc == &noop_qdisc) 268 return -ENODEV; 269 270 if (dev->header_ops == NULL || 271 skb_dst(skb) == NULL || 272 skb_dst(skb)->neighbour == NULL) 273 return 0; 274 return __teql_resolve(skb, skb_res, dev); 275 } 276 277 static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev) 278 { 279 struct teql_master *master = netdev_priv(dev); 280 struct Qdisc *start, *q; 281 int busy; 282 int nores; 283 int subq = skb_get_queue_mapping(skb); 284 struct sk_buff *skb_res = NULL; 285 286 start = master->slaves; 287 288 restart: 289 nores = 0; 290 busy = 0; 291 292 q = start; 293 if (!q) 294 goto drop; 295 296 do { 297 struct net_device *slave = qdisc_dev(q); 298 struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0); 299 const struct net_device_ops *slave_ops = slave->netdev_ops; 300 301 if (slave_txq->qdisc_sleeping != q) 302 continue; 303 if (__netif_subqueue_stopped(slave, subq) || 304 !netif_running(slave)) { 305 busy = 1; 306 continue; 307 } 308 309 switch (teql_resolve(skb, skb_res, slave)) { 310 case 0: 311 if (__netif_tx_trylock(slave_txq)) { 312 unsigned int length = qdisc_pkt_len(skb); 313 314 if (!netif_tx_queue_frozen_or_stopped(slave_txq) && 315 slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) { 316 txq_trans_update(slave_txq); 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_queue_stopped(dev)) 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 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; 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), 484 "teql%d", 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"); 529