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; 99 100 skb = __skb_dequeue(&dat->q); 101 dat_queue = netdev_get_tx_queue(dat->m->dev, 0); 102 if (skb == NULL) { 103 struct net_device *m = qdisc_dev(dat_queue->qdisc); 104 if (m) { 105 dat->m->slaves = sch; 106 netif_wake_queue(m); 107 } 108 } else { 109 qdisc_bstats_update(sch, skb); 110 } 111 sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen; 112 return skb; 113 } 114 115 static struct sk_buff * 116 teql_peek(struct Qdisc *sch) 117 { 118 /* teql is meant to be used as root qdisc */ 119 return NULL; 120 } 121 122 static inline void 123 teql_neigh_release(struct neighbour *n) 124 { 125 if (n) 126 neigh_release(n); 127 } 128 129 static void 130 teql_reset(struct Qdisc *sch) 131 { 132 struct teql_sched_data *dat = qdisc_priv(sch); 133 134 skb_queue_purge(&dat->q); 135 sch->q.qlen = 0; 136 } 137 138 static void 139 teql_destroy(struct Qdisc *sch) 140 { 141 struct Qdisc *q, *prev; 142 struct teql_sched_data *dat = qdisc_priv(sch); 143 struct teql_master *master = dat->m; 144 145 prev = master->slaves; 146 if (prev) { 147 do { 148 q = NEXT_SLAVE(prev); 149 if (q == sch) { 150 NEXT_SLAVE(prev) = NEXT_SLAVE(q); 151 if (q == master->slaves) { 152 master->slaves = NEXT_SLAVE(q); 153 if (q == master->slaves) { 154 struct netdev_queue *txq; 155 spinlock_t *root_lock; 156 157 txq = netdev_get_tx_queue(master->dev, 0); 158 master->slaves = NULL; 159 160 root_lock = qdisc_root_sleeping_lock(txq->qdisc); 161 spin_lock_bh(root_lock); 162 qdisc_reset(txq->qdisc); 163 spin_unlock_bh(root_lock); 164 } 165 } 166 skb_queue_purge(&dat->q); 167 break; 168 } 169 170 } while ((prev = q) != master->slaves); 171 } 172 } 173 174 static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt) 175 { 176 struct net_device *dev = qdisc_dev(sch); 177 struct teql_master *m = (struct teql_master *)sch->ops; 178 struct teql_sched_data *q = qdisc_priv(sch); 179 180 if (dev->hard_header_len > m->dev->hard_header_len) 181 return -EINVAL; 182 183 if (m->dev == dev) 184 return -ELOOP; 185 186 q->m = m; 187 188 skb_queue_head_init(&q->q); 189 190 if (m->slaves) { 191 if (m->dev->flags & IFF_UP) { 192 if ((m->dev->flags & IFF_POINTOPOINT && 193 !(dev->flags & IFF_POINTOPOINT)) || 194 (m->dev->flags & IFF_BROADCAST && 195 !(dev->flags & IFF_BROADCAST)) || 196 (m->dev->flags & IFF_MULTICAST && 197 !(dev->flags & IFF_MULTICAST)) || 198 dev->mtu < m->dev->mtu) 199 return -EINVAL; 200 } else { 201 if (!(dev->flags&IFF_POINTOPOINT)) 202 m->dev->flags &= ~IFF_POINTOPOINT; 203 if (!(dev->flags&IFF_BROADCAST)) 204 m->dev->flags &= ~IFF_BROADCAST; 205 if (!(dev->flags&IFF_MULTICAST)) 206 m->dev->flags &= ~IFF_MULTICAST; 207 if (dev->mtu < m->dev->mtu) 208 m->dev->mtu = dev->mtu; 209 } 210 q->next = NEXT_SLAVE(m->slaves); 211 NEXT_SLAVE(m->slaves) = sch; 212 } else { 213 q->next = sch; 214 m->slaves = sch; 215 m->dev->mtu = dev->mtu; 216 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK); 217 } 218 return 0; 219 } 220 221 222 static int 223 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, 224 struct net_device *dev, struct netdev_queue *txq, 225 struct dst_entry *dst) 226 { 227 struct neighbour *n; 228 int err = 0; 229 230 n = dst_neigh_lookup_skb(dst, skb); 231 if (!n) 232 return -ENOENT; 233 234 if (dst->dev != dev) { 235 struct neighbour *mn; 236 237 mn = __neigh_lookup_errno(n->tbl, n->primary_key, dev); 238 neigh_release(n); 239 if (IS_ERR(mn)) 240 return PTR_ERR(mn); 241 n = mn; 242 } 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 err = -EINVAL; 254 } else { 255 err = (skb_res == NULL) ? -EAGAIN : 1; 256 } 257 neigh_release(n); 258 return err; 259 } 260 261 static inline int teql_resolve(struct sk_buff *skb, 262 struct sk_buff *skb_res, 263 struct net_device *dev, 264 struct netdev_queue *txq) 265 { 266 struct dst_entry *dst = skb_dst(skb); 267 int res; 268 269 if (txq->qdisc == &noop_qdisc) 270 return -ENODEV; 271 272 if (!dev->header_ops || !dst) 273 return 0; 274 275 rcu_read_lock(); 276 res = __teql_resolve(skb, skb_res, dev, txq, dst); 277 rcu_read_unlock(); 278 279 return res; 280 } 281 282 static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev) 283 { 284 struct teql_master *master = netdev_priv(dev); 285 struct Qdisc *start, *q; 286 int busy; 287 int nores; 288 int subq = skb_get_queue_mapping(skb); 289 struct sk_buff *skb_res = NULL; 290 291 start = master->slaves; 292 293 restart: 294 nores = 0; 295 busy = 0; 296 297 q = start; 298 if (!q) 299 goto drop; 300 301 do { 302 struct net_device *slave = qdisc_dev(q); 303 struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0); 304 const struct net_device_ops *slave_ops = slave->netdev_ops; 305 306 if (slave_txq->qdisc_sleeping != q) 307 continue; 308 if (netif_xmit_stopped(netdev_get_tx_queue(slave, subq)) || 309 !netif_running(slave)) { 310 busy = 1; 311 continue; 312 } 313 314 switch (teql_resolve(skb, skb_res, slave, slave_txq)) { 315 case 0: 316 if (__netif_tx_trylock(slave_txq)) { 317 unsigned int length = qdisc_pkt_len(skb); 318 319 if (!netif_xmit_frozen_or_stopped(slave_txq) && 320 slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) { 321 txq_trans_update(slave_txq); 322 __netif_tx_unlock(slave_txq); 323 master->slaves = NEXT_SLAVE(q); 324 netif_wake_queue(dev); 325 master->tx_packets++; 326 master->tx_bytes += length; 327 return NETDEV_TX_OK; 328 } 329 __netif_tx_unlock(slave_txq); 330 } 331 if (netif_xmit_stopped(netdev_get_tx_queue(dev, 0))) 332 busy = 1; 333 break; 334 case 1: 335 master->slaves = NEXT_SLAVE(q); 336 return NETDEV_TX_OK; 337 default: 338 nores = 1; 339 break; 340 } 341 __skb_pull(skb, skb_network_offset(skb)); 342 } while ((q = NEXT_SLAVE(q)) != start); 343 344 if (nores && skb_res == NULL) { 345 skb_res = skb; 346 goto restart; 347 } 348 349 if (busy) { 350 netif_stop_queue(dev); 351 return NETDEV_TX_BUSY; 352 } 353 master->tx_errors++; 354 355 drop: 356 master->tx_dropped++; 357 dev_kfree_skb(skb); 358 return NETDEV_TX_OK; 359 } 360 361 static int teql_master_open(struct net_device *dev) 362 { 363 struct Qdisc *q; 364 struct teql_master *m = netdev_priv(dev); 365 int mtu = 0xFFFE; 366 unsigned int flags = IFF_NOARP | IFF_MULTICAST; 367 368 if (m->slaves == NULL) 369 return -EUNATCH; 370 371 flags = FMASK; 372 373 q = m->slaves; 374 do { 375 struct net_device *slave = qdisc_dev(q); 376 377 if (slave == NULL) 378 return -EUNATCH; 379 380 if (slave->mtu < mtu) 381 mtu = slave->mtu; 382 if (slave->hard_header_len > LL_MAX_HEADER) 383 return -EINVAL; 384 385 /* If all the slaves are BROADCAST, master is BROADCAST 386 If all the slaves are PtP, master is PtP 387 Otherwise, master is NBMA. 388 */ 389 if (!(slave->flags&IFF_POINTOPOINT)) 390 flags &= ~IFF_POINTOPOINT; 391 if (!(slave->flags&IFF_BROADCAST)) 392 flags &= ~IFF_BROADCAST; 393 if (!(slave->flags&IFF_MULTICAST)) 394 flags &= ~IFF_MULTICAST; 395 } while ((q = NEXT_SLAVE(q)) != m->slaves); 396 397 m->dev->mtu = mtu; 398 m->dev->flags = (m->dev->flags&~FMASK) | flags; 399 netif_start_queue(m->dev); 400 return 0; 401 } 402 403 static int teql_master_close(struct net_device *dev) 404 { 405 netif_stop_queue(dev); 406 return 0; 407 } 408 409 static struct rtnl_link_stats64 *teql_master_stats64(struct net_device *dev, 410 struct rtnl_link_stats64 *stats) 411 { 412 struct teql_master *m = netdev_priv(dev); 413 414 stats->tx_packets = m->tx_packets; 415 stats->tx_bytes = m->tx_bytes; 416 stats->tx_errors = m->tx_errors; 417 stats->tx_dropped = m->tx_dropped; 418 return stats; 419 } 420 421 static int teql_master_mtu(struct net_device *dev, int new_mtu) 422 { 423 struct teql_master *m = netdev_priv(dev); 424 struct Qdisc *q; 425 426 if (new_mtu < 68) 427 return -EINVAL; 428 429 q = m->slaves; 430 if (q) { 431 do { 432 if (new_mtu > qdisc_dev(q)->mtu) 433 return -EINVAL; 434 } while ((q = NEXT_SLAVE(q)) != m->slaves); 435 } 436 437 dev->mtu = new_mtu; 438 return 0; 439 } 440 441 static const struct net_device_ops teql_netdev_ops = { 442 .ndo_open = teql_master_open, 443 .ndo_stop = teql_master_close, 444 .ndo_start_xmit = teql_master_xmit, 445 .ndo_get_stats64 = teql_master_stats64, 446 .ndo_change_mtu = teql_master_mtu, 447 }; 448 449 static __init void teql_master_setup(struct net_device *dev) 450 { 451 struct teql_master *master = netdev_priv(dev); 452 struct Qdisc_ops *ops = &master->qops; 453 454 master->dev = dev; 455 ops->priv_size = sizeof(struct teql_sched_data); 456 457 ops->enqueue = teql_enqueue; 458 ops->dequeue = teql_dequeue; 459 ops->peek = teql_peek; 460 ops->init = teql_qdisc_init; 461 ops->reset = teql_reset; 462 ops->destroy = teql_destroy; 463 ops->owner = THIS_MODULE; 464 465 dev->netdev_ops = &teql_netdev_ops; 466 dev->type = ARPHRD_VOID; 467 dev->mtu = 1500; 468 dev->tx_queue_len = 100; 469 dev->flags = IFF_NOARP; 470 dev->hard_header_len = LL_MAX_HEADER; 471 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; 472 } 473 474 static LIST_HEAD(master_dev_list); 475 static int max_equalizers = 1; 476 module_param(max_equalizers, int, 0); 477 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers"); 478 479 static int __init teql_init(void) 480 { 481 int i; 482 int err = -ENODEV; 483 484 for (i = 0; i < max_equalizers; i++) { 485 struct net_device *dev; 486 struct teql_master *master; 487 488 dev = alloc_netdev(sizeof(struct teql_master), 489 "teql%d", teql_master_setup); 490 if (!dev) { 491 err = -ENOMEM; 492 break; 493 } 494 495 if ((err = register_netdev(dev))) { 496 free_netdev(dev); 497 break; 498 } 499 500 master = netdev_priv(dev); 501 502 strlcpy(master->qops.id, dev->name, IFNAMSIZ); 503 err = register_qdisc(&master->qops); 504 505 if (err) { 506 unregister_netdev(dev); 507 free_netdev(dev); 508 break; 509 } 510 511 list_add_tail(&master->master_list, &master_dev_list); 512 } 513 return i ? 0 : err; 514 } 515 516 static void __exit teql_exit(void) 517 { 518 struct teql_master *master, *nxt; 519 520 list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) { 521 522 list_del(&master->master_list); 523 524 unregister_qdisc(&master->qops); 525 unregister_netdev(master->dev); 526 free_netdev(master->dev); 527 } 528 } 529 530 module_init(teql_init); 531 module_exit(teql_exit); 532 533 MODULE_LICENSE("GPL"); 534