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, struct sk_buff **to_free) 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, to_free); 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 void 126 teql_reset(struct Qdisc *sch) 127 { 128 struct teql_sched_data *dat = qdisc_priv(sch); 129 130 skb_queue_purge(&dat->q); 131 sch->q.qlen = 0; 132 } 133 134 static void 135 teql_destroy(struct Qdisc *sch) 136 { 137 struct Qdisc *q, *prev; 138 struct teql_sched_data *dat = qdisc_priv(sch); 139 struct teql_master *master = dat->m; 140 141 prev = master->slaves; 142 if (prev) { 143 do { 144 q = NEXT_SLAVE(prev); 145 if (q == sch) { 146 NEXT_SLAVE(prev) = NEXT_SLAVE(q); 147 if (q == master->slaves) { 148 master->slaves = NEXT_SLAVE(q); 149 if (q == master->slaves) { 150 struct netdev_queue *txq; 151 spinlock_t *root_lock; 152 153 txq = netdev_get_tx_queue(master->dev, 0); 154 master->slaves = NULL; 155 156 root_lock = qdisc_root_sleeping_lock(rtnl_dereference(txq->qdisc)); 157 spin_lock_bh(root_lock); 158 qdisc_reset(rtnl_dereference(txq->qdisc)); 159 spin_unlock_bh(root_lock); 160 } 161 } 162 skb_queue_purge(&dat->q); 163 break; 164 } 165 166 } while ((prev = q) != master->slaves); 167 } 168 } 169 170 static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt) 171 { 172 struct net_device *dev = qdisc_dev(sch); 173 struct teql_master *m = (struct teql_master *)sch->ops; 174 struct teql_sched_data *q = qdisc_priv(sch); 175 176 if (dev->hard_header_len > m->dev->hard_header_len) 177 return -EINVAL; 178 179 if (m->dev == dev) 180 return -ELOOP; 181 182 q->m = m; 183 184 skb_queue_head_init(&q->q); 185 186 if (m->slaves) { 187 if (m->dev->flags & IFF_UP) { 188 if ((m->dev->flags & IFF_POINTOPOINT && 189 !(dev->flags & IFF_POINTOPOINT)) || 190 (m->dev->flags & IFF_BROADCAST && 191 !(dev->flags & IFF_BROADCAST)) || 192 (m->dev->flags & IFF_MULTICAST && 193 !(dev->flags & IFF_MULTICAST)) || 194 dev->mtu < m->dev->mtu) 195 return -EINVAL; 196 } else { 197 if (!(dev->flags&IFF_POINTOPOINT)) 198 m->dev->flags &= ~IFF_POINTOPOINT; 199 if (!(dev->flags&IFF_BROADCAST)) 200 m->dev->flags &= ~IFF_BROADCAST; 201 if (!(dev->flags&IFF_MULTICAST)) 202 m->dev->flags &= ~IFF_MULTICAST; 203 if (dev->mtu < m->dev->mtu) 204 m->dev->mtu = dev->mtu; 205 } 206 q->next = NEXT_SLAVE(m->slaves); 207 NEXT_SLAVE(m->slaves) = sch; 208 } else { 209 q->next = sch; 210 m->slaves = sch; 211 m->dev->mtu = dev->mtu; 212 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK); 213 } 214 return 0; 215 } 216 217 218 static int 219 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, 220 struct net_device *dev, struct netdev_queue *txq, 221 struct dst_entry *dst) 222 { 223 struct neighbour *n; 224 int err = 0; 225 226 n = dst_neigh_lookup_skb(dst, skb); 227 if (!n) 228 return -ENOENT; 229 230 if (dst->dev != dev) { 231 struct neighbour *mn; 232 233 mn = __neigh_lookup_errno(n->tbl, n->primary_key, dev); 234 neigh_release(n); 235 if (IS_ERR(mn)) 236 return PTR_ERR(mn); 237 n = mn; 238 } 239 240 if (neigh_event_send(n, skb_res) == 0) { 241 int err; 242 char haddr[MAX_ADDR_LEN]; 243 244 neigh_ha_snapshot(haddr, n, dev); 245 err = dev_hard_header(skb, dev, ntohs(tc_skb_protocol(skb)), 246 haddr, NULL, skb->len); 247 248 if (err < 0) 249 err = -EINVAL; 250 } else { 251 err = (skb_res == NULL) ? -EAGAIN : 1; 252 } 253 neigh_release(n); 254 return err; 255 } 256 257 static inline int teql_resolve(struct sk_buff *skb, 258 struct sk_buff *skb_res, 259 struct net_device *dev, 260 struct netdev_queue *txq) 261 { 262 struct dst_entry *dst = skb_dst(skb); 263 int res; 264 265 if (rcu_access_pointer(txq->qdisc) == &noop_qdisc) 266 return -ENODEV; 267 268 if (!dev->header_ops || !dst) 269 return 0; 270 271 rcu_read_lock(); 272 res = __teql_resolve(skb, skb_res, dev, txq, dst); 273 rcu_read_unlock(); 274 275 return res; 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); 300 301 if (slave_txq->qdisc_sleeping != q) 302 continue; 303 if (netif_xmit_stopped(netdev_get_tx_queue(slave, subq)) || 304 !netif_running(slave)) { 305 busy = 1; 306 continue; 307 } 308 309 switch (teql_resolve(skb, skb_res, slave, slave_txq)) { 310 case 0: 311 if (__netif_tx_trylock(slave_txq)) { 312 unsigned int length = qdisc_pkt_len(skb); 313 314 if (!netif_xmit_frozen_or_stopped(slave_txq) && 315 netdev_start_xmit(skb, slave, slave_txq, false) == 316 NETDEV_TX_OK) { 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_xmit_stopped(netdev_get_tx_queue(dev, 0))) 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 netif_keep_dst(dev); 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), "teql%d", 484 NET_NAME_UNKNOWN, 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