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 return qdisc_drop(skb, sch); 92 } 93 94 static struct sk_buff * 95 teql_dequeue(struct Qdisc *sch) 96 { 97 struct teql_sched_data *dat = qdisc_priv(sch); 98 struct netdev_queue *dat_queue; 99 struct sk_buff *skb; 100 101 skb = __skb_dequeue(&dat->q); 102 dat_queue = netdev_get_tx_queue(dat->m->dev, 0); 103 if (skb == NULL) { 104 struct net_device *m = qdisc_dev(dat_queue->qdisc); 105 if (m) { 106 dat->m->slaves = sch; 107 netif_wake_queue(m); 108 } 109 } else { 110 qdisc_bstats_update(sch, skb); 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 prev = master->slaves; 148 if (prev) { 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 struct netdev_queue *txq; 157 spinlock_t *root_lock; 158 159 txq = netdev_get_tx_queue(master->dev, 0); 160 master->slaves = NULL; 161 162 root_lock = qdisc_root_sleeping_lock(txq->qdisc); 163 spin_lock_bh(root_lock); 164 qdisc_reset(txq->qdisc); 165 spin_unlock_bh(root_lock); 166 } 167 } 168 skb_queue_purge(&dat->q); 169 teql_neigh_release(xchg(&dat->ncache, NULL)); 170 break; 171 } 172 173 } while ((prev = q) != master->slaves); 174 } 175 } 176 177 static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt) 178 { 179 struct net_device *dev = qdisc_dev(sch); 180 struct teql_master *m = (struct teql_master *)sch->ops; 181 struct teql_sched_data *q = qdisc_priv(sch); 182 183 if (dev->hard_header_len > m->dev->hard_header_len) 184 return -EINVAL; 185 186 if (m->dev == dev) 187 return -ELOOP; 188 189 q->m = m; 190 191 skb_queue_head_init(&q->q); 192 193 if (m->slaves) { 194 if (m->dev->flags & IFF_UP) { 195 if ((m->dev->flags & IFF_POINTOPOINT && 196 !(dev->flags & IFF_POINTOPOINT)) || 197 (m->dev->flags & IFF_BROADCAST && 198 !(dev->flags & IFF_BROADCAST)) || 199 (m->dev->flags & IFF_MULTICAST && 200 !(dev->flags & IFF_MULTICAST)) || 201 dev->mtu < m->dev->mtu) 202 return -EINVAL; 203 } else { 204 if (!(dev->flags&IFF_POINTOPOINT)) 205 m->dev->flags &= ~IFF_POINTOPOINT; 206 if (!(dev->flags&IFF_BROADCAST)) 207 m->dev->flags &= ~IFF_BROADCAST; 208 if (!(dev->flags&IFF_MULTICAST)) 209 m->dev->flags &= ~IFF_MULTICAST; 210 if (dev->mtu < m->dev->mtu) 211 m->dev->mtu = dev->mtu; 212 } 213 q->next = NEXT_SLAVE(m->slaves); 214 NEXT_SLAVE(m->slaves) = sch; 215 } else { 216 q->next = sch; 217 m->slaves = sch; 218 m->dev->mtu = dev->mtu; 219 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK); 220 } 221 return 0; 222 } 223 224 225 static int 226 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, 227 struct net_device *dev, struct netdev_queue *txq, 228 struct neighbour *mn) 229 { 230 struct teql_sched_data *q = qdisc_priv(txq->qdisc); 231 struct neighbour *n = q->ncache; 232 233 if (mn->tbl == NULL) 234 return -EINVAL; 235 if (n && n->tbl == mn->tbl && 236 memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) { 237 atomic_inc(&n->refcnt); 238 } else { 239 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev); 240 if (IS_ERR(n)) 241 return PTR_ERR(n); 242 } 243 if (neigh_event_send(n, skb_res) == 0) { 244 int err; 245 char haddr[MAX_ADDR_LEN]; 246 247 neigh_ha_snapshot(haddr, n, dev); 248 err = dev_hard_header(skb, dev, ntohs(skb->protocol), haddr, 249 NULL, skb->len); 250 251 if (err < 0) { 252 neigh_release(n); 253 return -EINVAL; 254 } 255 teql_neigh_release(xchg(&q->ncache, n)); 256 return 0; 257 } 258 neigh_release(n); 259 return (skb_res == NULL) ? -EAGAIN : 1; 260 } 261 262 static inline int teql_resolve(struct sk_buff *skb, 263 struct sk_buff *skb_res, 264 struct net_device *dev, 265 struct netdev_queue *txq) 266 { 267 struct dst_entry *dst = skb_dst(skb); 268 struct neighbour *mn; 269 int res; 270 271 if (txq->qdisc == &noop_qdisc) 272 return -ENODEV; 273 274 if (!dev->header_ops || !dst) 275 return 0; 276 277 rcu_read_lock(); 278 mn = dst_get_neighbour_noref(dst); 279 res = mn ? __teql_resolve(skb, skb_res, dev, txq, mn) : 0; 280 rcu_read_unlock(); 281 282 return res; 283 } 284 285 static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev) 286 { 287 struct teql_master *master = netdev_priv(dev); 288 struct Qdisc *start, *q; 289 int busy; 290 int nores; 291 int subq = skb_get_queue_mapping(skb); 292 struct sk_buff *skb_res = NULL; 293 294 start = master->slaves; 295 296 restart: 297 nores = 0; 298 busy = 0; 299 300 q = start; 301 if (!q) 302 goto drop; 303 304 do { 305 struct net_device *slave = qdisc_dev(q); 306 struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0); 307 const struct net_device_ops *slave_ops = slave->netdev_ops; 308 309 if (slave_txq->qdisc_sleeping != q) 310 continue; 311 if (netif_xmit_stopped(netdev_get_tx_queue(slave, subq)) || 312 !netif_running(slave)) { 313 busy = 1; 314 continue; 315 } 316 317 switch (teql_resolve(skb, skb_res, slave, slave_txq)) { 318 case 0: 319 if (__netif_tx_trylock(slave_txq)) { 320 unsigned int length = qdisc_pkt_len(skb); 321 322 if (!netif_xmit_frozen_or_stopped(slave_txq) && 323 slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) { 324 txq_trans_update(slave_txq); 325 __netif_tx_unlock(slave_txq); 326 master->slaves = NEXT_SLAVE(q); 327 netif_wake_queue(dev); 328 master->tx_packets++; 329 master->tx_bytes += length; 330 return NETDEV_TX_OK; 331 } 332 __netif_tx_unlock(slave_txq); 333 } 334 if (netif_xmit_stopped(netdev_get_tx_queue(dev, 0))) 335 busy = 1; 336 break; 337 case 1: 338 master->slaves = NEXT_SLAVE(q); 339 return NETDEV_TX_OK; 340 default: 341 nores = 1; 342 break; 343 } 344 __skb_pull(skb, skb_network_offset(skb)); 345 } while ((q = NEXT_SLAVE(q)) != start); 346 347 if (nores && skb_res == NULL) { 348 skb_res = skb; 349 goto restart; 350 } 351 352 if (busy) { 353 netif_stop_queue(dev); 354 return NETDEV_TX_BUSY; 355 } 356 master->tx_errors++; 357 358 drop: 359 master->tx_dropped++; 360 dev_kfree_skb(skb); 361 return NETDEV_TX_OK; 362 } 363 364 static int teql_master_open(struct net_device *dev) 365 { 366 struct Qdisc *q; 367 struct teql_master *m = netdev_priv(dev); 368 int mtu = 0xFFFE; 369 unsigned int flags = IFF_NOARP | IFF_MULTICAST; 370 371 if (m->slaves == NULL) 372 return -EUNATCH; 373 374 flags = FMASK; 375 376 q = m->slaves; 377 do { 378 struct net_device *slave = qdisc_dev(q); 379 380 if (slave == NULL) 381 return -EUNATCH; 382 383 if (slave->mtu < mtu) 384 mtu = slave->mtu; 385 if (slave->hard_header_len > LL_MAX_HEADER) 386 return -EINVAL; 387 388 /* If all the slaves are BROADCAST, master is BROADCAST 389 If all the slaves are PtP, master is PtP 390 Otherwise, master is NBMA. 391 */ 392 if (!(slave->flags&IFF_POINTOPOINT)) 393 flags &= ~IFF_POINTOPOINT; 394 if (!(slave->flags&IFF_BROADCAST)) 395 flags &= ~IFF_BROADCAST; 396 if (!(slave->flags&IFF_MULTICAST)) 397 flags &= ~IFF_MULTICAST; 398 } while ((q = NEXT_SLAVE(q)) != m->slaves); 399 400 m->dev->mtu = mtu; 401 m->dev->flags = (m->dev->flags&~FMASK) | flags; 402 netif_start_queue(m->dev); 403 return 0; 404 } 405 406 static int teql_master_close(struct net_device *dev) 407 { 408 netif_stop_queue(dev); 409 return 0; 410 } 411 412 static struct rtnl_link_stats64 *teql_master_stats64(struct net_device *dev, 413 struct rtnl_link_stats64 *stats) 414 { 415 struct teql_master *m = netdev_priv(dev); 416 417 stats->tx_packets = m->tx_packets; 418 stats->tx_bytes = m->tx_bytes; 419 stats->tx_errors = m->tx_errors; 420 stats->tx_dropped = m->tx_dropped; 421 return stats; 422 } 423 424 static int teql_master_mtu(struct net_device *dev, int new_mtu) 425 { 426 struct teql_master *m = netdev_priv(dev); 427 struct Qdisc *q; 428 429 if (new_mtu < 68) 430 return -EINVAL; 431 432 q = m->slaves; 433 if (q) { 434 do { 435 if (new_mtu > qdisc_dev(q)->mtu) 436 return -EINVAL; 437 } while ((q = NEXT_SLAVE(q)) != m->slaves); 438 } 439 440 dev->mtu = new_mtu; 441 return 0; 442 } 443 444 static const struct net_device_ops teql_netdev_ops = { 445 .ndo_open = teql_master_open, 446 .ndo_stop = teql_master_close, 447 .ndo_start_xmit = teql_master_xmit, 448 .ndo_get_stats64 = teql_master_stats64, 449 .ndo_change_mtu = teql_master_mtu, 450 }; 451 452 static __init void teql_master_setup(struct net_device *dev) 453 { 454 struct teql_master *master = netdev_priv(dev); 455 struct Qdisc_ops *ops = &master->qops; 456 457 master->dev = dev; 458 ops->priv_size = sizeof(struct teql_sched_data); 459 460 ops->enqueue = teql_enqueue; 461 ops->dequeue = teql_dequeue; 462 ops->peek = teql_peek; 463 ops->init = teql_qdisc_init; 464 ops->reset = teql_reset; 465 ops->destroy = teql_destroy; 466 ops->owner = THIS_MODULE; 467 468 dev->netdev_ops = &teql_netdev_ops; 469 dev->type = ARPHRD_VOID; 470 dev->mtu = 1500; 471 dev->tx_queue_len = 100; 472 dev->flags = IFF_NOARP; 473 dev->hard_header_len = LL_MAX_HEADER; 474 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; 475 } 476 477 static LIST_HEAD(master_dev_list); 478 static int max_equalizers = 1; 479 module_param(max_equalizers, int, 0); 480 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers"); 481 482 static int __init teql_init(void) 483 { 484 int i; 485 int err = -ENODEV; 486 487 for (i = 0; i < max_equalizers; i++) { 488 struct net_device *dev; 489 struct teql_master *master; 490 491 dev = alloc_netdev(sizeof(struct teql_master), 492 "teql%d", teql_master_setup); 493 if (!dev) { 494 err = -ENOMEM; 495 break; 496 } 497 498 if ((err = register_netdev(dev))) { 499 free_netdev(dev); 500 break; 501 } 502 503 master = netdev_priv(dev); 504 505 strlcpy(master->qops.id, dev->name, IFNAMSIZ); 506 err = register_qdisc(&master->qops); 507 508 if (err) { 509 unregister_netdev(dev); 510 free_netdev(dev); 511 break; 512 } 513 514 list_add_tail(&master->master_list, &master_dev_list); 515 } 516 return i ? 0 : err; 517 } 518 519 static void __exit teql_exit(void) 520 { 521 struct teql_master *master, *nxt; 522 523 list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) { 524 525 list_del(&master->master_list); 526 527 unregister_qdisc(&master->qops); 528 unregister_netdev(master->dev); 529 free_netdev(master->dev); 530 } 531 } 532 533 module_init(teql_init); 534 module_exit(teql_exit); 535 536 MODULE_LICENSE("GPL"); 537