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