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 sk_buff_head q; 71 }; 72 73 #define NEXT_SLAVE(q) (((struct teql_sched_data *)qdisc_priv(q))->next) 74 75 #define FMASK (IFF_BROADCAST | IFF_POINTOPOINT) 76 77 /* "teql*" qdisc routines */ 78 79 static int 80 teql_enqueue(struct sk_buff *skb, struct Qdisc *sch) 81 { 82 struct net_device *dev = qdisc_dev(sch); 83 struct teql_sched_data *q = qdisc_priv(sch); 84 85 if (q->q.qlen < dev->tx_queue_len) { 86 __skb_queue_tail(&q->q, skb); 87 return NET_XMIT_SUCCESS; 88 } 89 90 return qdisc_drop(skb, sch); 91 } 92 93 static struct sk_buff * 94 teql_dequeue(struct Qdisc *sch) 95 { 96 struct teql_sched_data *dat = qdisc_priv(sch); 97 struct netdev_queue *dat_queue; 98 struct sk_buff *skb; 99 struct Qdisc *q; 100 101 skb = __skb_dequeue(&dat->q); 102 dat_queue = netdev_get_tx_queue(dat->m->dev, 0); 103 q = rcu_dereference_bh(dat_queue->qdisc); 104 105 if (skb == NULL) { 106 struct net_device *m = qdisc_dev(q); 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 + q->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 } 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(rtnl_dereference(txq->qdisc)); 164 spin_lock_bh(root_lock); 165 qdisc_reset(rtnl_dereference(txq->qdisc)); 166 spin_unlock_bh(root_lock); 167 } 168 } 169 skb_queue_purge(&dat->q); 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 dst_entry *dst) 229 { 230 struct neighbour *n; 231 int err = 0; 232 233 n = dst_neigh_lookup_skb(dst, skb); 234 if (!n) 235 return -ENOENT; 236 237 if (dst->dev != dev) { 238 struct neighbour *mn; 239 240 mn = __neigh_lookup_errno(n->tbl, n->primary_key, dev); 241 neigh_release(n); 242 if (IS_ERR(mn)) 243 return PTR_ERR(mn); 244 n = mn; 245 } 246 247 if (neigh_event_send(n, skb_res) == 0) { 248 int err; 249 char haddr[MAX_ADDR_LEN]; 250 251 neigh_ha_snapshot(haddr, n, dev); 252 err = dev_hard_header(skb, dev, ntohs(skb->protocol), haddr, 253 NULL, skb->len); 254 255 if (err < 0) 256 err = -EINVAL; 257 } else { 258 err = (skb_res == NULL) ? -EAGAIN : 1; 259 } 260 neigh_release(n); 261 return err; 262 } 263 264 static inline int teql_resolve(struct sk_buff *skb, 265 struct sk_buff *skb_res, 266 struct net_device *dev, 267 struct netdev_queue *txq) 268 { 269 struct dst_entry *dst = skb_dst(skb); 270 int res; 271 272 if (rcu_access_pointer(txq->qdisc) == &noop_qdisc) 273 return -ENODEV; 274 275 if (!dev->header_ops || !dst) 276 return 0; 277 278 rcu_read_lock(); 279 res = __teql_resolve(skb, skb_res, dev, txq, dst); 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); 307 308 if (slave_txq->qdisc_sleeping != q) 309 continue; 310 if (netif_xmit_stopped(netdev_get_tx_queue(slave, subq)) || 311 !netif_running(slave)) { 312 busy = 1; 313 continue; 314 } 315 316 switch (teql_resolve(skb, skb_res, slave, slave_txq)) { 317 case 0: 318 if (__netif_tx_trylock(slave_txq)) { 319 unsigned int length = qdisc_pkt_len(skb); 320 321 if (!netif_xmit_frozen_or_stopped(slave_txq) && 322 netdev_start_xmit(skb, slave, slave_txq, false) == 323 NETDEV_TX_OK) { 324 __netif_tx_unlock(slave_txq); 325 master->slaves = NEXT_SLAVE(q); 326 netif_wake_queue(dev); 327 master->tx_packets++; 328 master->tx_bytes += length; 329 return NETDEV_TX_OK; 330 } 331 __netif_tx_unlock(slave_txq); 332 } 333 if (netif_xmit_stopped(netdev_get_tx_queue(dev, 0))) 334 busy = 1; 335 break; 336 case 1: 337 master->slaves = NEXT_SLAVE(q); 338 return NETDEV_TX_OK; 339 default: 340 nores = 1; 341 break; 342 } 343 __skb_pull(skb, skb_network_offset(skb)); 344 } while ((q = NEXT_SLAVE(q)) != start); 345 346 if (nores && skb_res == NULL) { 347 skb_res = skb; 348 goto restart; 349 } 350 351 if (busy) { 352 netif_stop_queue(dev); 353 return NETDEV_TX_BUSY; 354 } 355 master->tx_errors++; 356 357 drop: 358 master->tx_dropped++; 359 dev_kfree_skb(skb); 360 return NETDEV_TX_OK; 361 } 362 363 static int teql_master_open(struct net_device *dev) 364 { 365 struct Qdisc *q; 366 struct teql_master *m = netdev_priv(dev); 367 int mtu = 0xFFFE; 368 unsigned int flags = IFF_NOARP | IFF_MULTICAST; 369 370 if (m->slaves == NULL) 371 return -EUNATCH; 372 373 flags = FMASK; 374 375 q = m->slaves; 376 do { 377 struct net_device *slave = qdisc_dev(q); 378 379 if (slave == NULL) 380 return -EUNATCH; 381 382 if (slave->mtu < mtu) 383 mtu = slave->mtu; 384 if (slave->hard_header_len > LL_MAX_HEADER) 385 return -EINVAL; 386 387 /* If all the slaves are BROADCAST, master is BROADCAST 388 If all the slaves are PtP, master is PtP 389 Otherwise, master is NBMA. 390 */ 391 if (!(slave->flags&IFF_POINTOPOINT)) 392 flags &= ~IFF_POINTOPOINT; 393 if (!(slave->flags&IFF_BROADCAST)) 394 flags &= ~IFF_BROADCAST; 395 if (!(slave->flags&IFF_MULTICAST)) 396 flags &= ~IFF_MULTICAST; 397 } while ((q = NEXT_SLAVE(q)) != m->slaves); 398 399 m->dev->mtu = mtu; 400 m->dev->flags = (m->dev->flags&~FMASK) | flags; 401 netif_start_queue(m->dev); 402 return 0; 403 } 404 405 static int teql_master_close(struct net_device *dev) 406 { 407 netif_stop_queue(dev); 408 return 0; 409 } 410 411 static struct rtnl_link_stats64 *teql_master_stats64(struct net_device *dev, 412 struct rtnl_link_stats64 *stats) 413 { 414 struct teql_master *m = netdev_priv(dev); 415 416 stats->tx_packets = m->tx_packets; 417 stats->tx_bytes = m->tx_bytes; 418 stats->tx_errors = m->tx_errors; 419 stats->tx_dropped = m->tx_dropped; 420 return stats; 421 } 422 423 static int teql_master_mtu(struct net_device *dev, int new_mtu) 424 { 425 struct teql_master *m = netdev_priv(dev); 426 struct Qdisc *q; 427 428 if (new_mtu < 68) 429 return -EINVAL; 430 431 q = m->slaves; 432 if (q) { 433 do { 434 if (new_mtu > qdisc_dev(q)->mtu) 435 return -EINVAL; 436 } while ((q = NEXT_SLAVE(q)) != m->slaves); 437 } 438 439 dev->mtu = new_mtu; 440 return 0; 441 } 442 443 static const struct net_device_ops teql_netdev_ops = { 444 .ndo_open = teql_master_open, 445 .ndo_stop = teql_master_close, 446 .ndo_start_xmit = teql_master_xmit, 447 .ndo_get_stats64 = teql_master_stats64, 448 .ndo_change_mtu = teql_master_mtu, 449 }; 450 451 static __init void teql_master_setup(struct net_device *dev) 452 { 453 struct teql_master *master = netdev_priv(dev); 454 struct Qdisc_ops *ops = &master->qops; 455 456 master->dev = dev; 457 ops->priv_size = sizeof(struct teql_sched_data); 458 459 ops->enqueue = teql_enqueue; 460 ops->dequeue = teql_dequeue; 461 ops->peek = teql_peek; 462 ops->init = teql_qdisc_init; 463 ops->reset = teql_reset; 464 ops->destroy = teql_destroy; 465 ops->owner = THIS_MODULE; 466 467 dev->netdev_ops = &teql_netdev_ops; 468 dev->type = ARPHRD_VOID; 469 dev->mtu = 1500; 470 dev->tx_queue_len = 100; 471 dev->flags = IFF_NOARP; 472 dev->hard_header_len = LL_MAX_HEADER; 473 netif_keep_dst(dev); 474 } 475 476 static LIST_HEAD(master_dev_list); 477 static int max_equalizers = 1; 478 module_param(max_equalizers, int, 0); 479 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers"); 480 481 static int __init teql_init(void) 482 { 483 int i; 484 int err = -ENODEV; 485 486 for (i = 0; i < max_equalizers; i++) { 487 struct net_device *dev; 488 struct teql_master *master; 489 490 dev = alloc_netdev(sizeof(struct teql_master), "teql%d", 491 NET_NAME_UNKNOWN, teql_master_setup); 492 if (!dev) { 493 err = -ENOMEM; 494 break; 495 } 496 497 if ((err = register_netdev(dev))) { 498 free_netdev(dev); 499 break; 500 } 501 502 master = netdev_priv(dev); 503 504 strlcpy(master->qops.id, dev->name, IFNAMSIZ); 505 err = register_qdisc(&master->qops); 506 507 if (err) { 508 unregister_netdev(dev); 509 free_netdev(dev); 510 break; 511 } 512 513 list_add_tail(&master->master_list, &master_dev_list); 514 } 515 return i ? 0 : err; 516 } 517 518 static void __exit teql_exit(void) 519 { 520 struct teql_master *master, *nxt; 521 522 list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) { 523 524 list_del(&master->master_list); 525 526 unregister_qdisc(&master->qops); 527 unregister_netdev(master->dev); 528 free_netdev(master->dev); 529 } 530 } 531 532 module_init(teql_init); 533 module_exit(teql_exit); 534 535 MODULE_LICENSE("GPL"); 536