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/string.h> 15 #include <linux/errno.h> 16 #include <linux/if_arp.h> 17 #include <linux/netdevice.h> 18 #include <linux/init.h> 19 #include <linux/skbuff.h> 20 #include <linux/moduleparam.h> 21 #include <net/dst.h> 22 #include <net/neighbour.h> 23 #include <net/pkt_sched.h> 24 25 /* 26 How to setup it. 27 ---------------- 28 29 After loading this module you will find a new device teqlN 30 and new qdisc with the same name. To join a slave to the equalizer 31 you should just set this qdisc on a device f.e. 32 33 # tc qdisc add dev eth0 root teql0 34 # tc qdisc add dev eth1 root teql0 35 36 That's all. Full PnP 8) 37 38 Applicability. 39 -------------- 40 41 1. Slave devices MUST be active devices, i.e., they must raise the tbusy 42 signal and generate EOI events. If you want to equalize virtual devices 43 like tunnels, use a normal eql device. 44 2. This device puts no limitations on physical slave characteristics 45 f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-) 46 Certainly, large difference in link speeds will make the resulting 47 eqalized link unusable, because of huge packet reordering. 48 I estimate an upper useful difference as ~10 times. 49 3. If the slave requires address resolution, only protocols using 50 neighbour cache (IPv4/IPv6) will work over the equalized link. 51 Other protocols are still allowed to use the slave device directly, 52 which will not break load balancing, though native slave 53 traffic will have the highest priority. */ 54 55 struct teql_master 56 { 57 struct Qdisc_ops qops; 58 struct net_device *dev; 59 struct Qdisc *slaves; 60 struct list_head master_list; 61 }; 62 63 struct teql_sched_data 64 { 65 struct Qdisc *next; 66 struct teql_master *m; 67 struct neighbour *ncache; 68 struct sk_buff_head q; 69 }; 70 71 #define NEXT_SLAVE(q) (((struct teql_sched_data*)qdisc_priv(q))->next) 72 73 #define FMASK (IFF_BROADCAST|IFF_POINTOPOINT) 74 75 /* "teql*" qdisc routines */ 76 77 static int 78 teql_enqueue(struct sk_buff *skb, struct Qdisc* sch) 79 { 80 struct net_device *dev = qdisc_dev(sch); 81 struct teql_sched_data *q = qdisc_priv(sch); 82 83 if (q->q.qlen < dev->tx_queue_len) { 84 __skb_queue_tail(&q->q, skb); 85 sch->bstats.bytes += qdisc_pkt_len(skb); 86 sch->bstats.packets++; 87 return 0; 88 } 89 90 kfree_skb(skb); 91 sch->qstats.drops++; 92 return NET_XMIT_DROP; 93 } 94 95 static struct sk_buff * 96 teql_dequeue(struct Qdisc* sch) 97 { 98 struct teql_sched_data *dat = qdisc_priv(sch); 99 struct netdev_queue *dat_queue; 100 struct sk_buff *skb; 101 102 skb = __skb_dequeue(&dat->q); 103 dat_queue = netdev_get_tx_queue(dat->m->dev, 0); 104 if (skb == NULL) { 105 struct net_device *m = qdisc_dev(dat_queue->qdisc); 106 if (m) { 107 dat->m->slaves = sch; 108 netif_wake_queue(m); 109 } 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 teql_neigh_release(xchg(&dat->ncache, NULL)); 137 } 138 139 static void 140 teql_destroy(struct Qdisc* sch) 141 { 142 struct Qdisc *q, *prev; 143 struct teql_sched_data *dat = qdisc_priv(sch); 144 struct teql_master *master = dat->m; 145 146 if ((prev = master->slaves) != NULL) { 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 teql_neigh_release(xchg(&dat->ncache, NULL)); 168 break; 169 } 170 171 } while ((prev = q) != master->slaves); 172 } 173 } 174 175 static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt) 176 { 177 struct net_device *dev = qdisc_dev(sch); 178 struct teql_master *m = (struct teql_master*)sch->ops; 179 struct teql_sched_data *q = qdisc_priv(sch); 180 181 if (dev->hard_header_len > m->dev->hard_header_len) 182 return -EINVAL; 183 184 if (m->dev == dev) 185 return -ELOOP; 186 187 q->m = m; 188 189 skb_queue_head_init(&q->q); 190 191 if (m->slaves) { 192 if (m->dev->flags & IFF_UP) { 193 if ((m->dev->flags&IFF_POINTOPOINT && !(dev->flags&IFF_POINTOPOINT)) 194 || (m->dev->flags&IFF_BROADCAST && !(dev->flags&IFF_BROADCAST)) 195 || (m->dev->flags&IFF_MULTICAST && !(dev->flags&IFF_MULTICAST)) 196 || dev->mtu < m->dev->mtu) 197 return -EINVAL; 198 } else { 199 if (!(dev->flags&IFF_POINTOPOINT)) 200 m->dev->flags &= ~IFF_POINTOPOINT; 201 if (!(dev->flags&IFF_BROADCAST)) 202 m->dev->flags &= ~IFF_BROADCAST; 203 if (!(dev->flags&IFF_MULTICAST)) 204 m->dev->flags &= ~IFF_MULTICAST; 205 if (dev->mtu < m->dev->mtu) 206 m->dev->mtu = dev->mtu; 207 } 208 q->next = NEXT_SLAVE(m->slaves); 209 NEXT_SLAVE(m->slaves) = sch; 210 } else { 211 q->next = sch; 212 m->slaves = sch; 213 m->dev->mtu = dev->mtu; 214 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK); 215 } 216 return 0; 217 } 218 219 220 static int 221 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev) 222 { 223 struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, 0); 224 struct teql_sched_data *q = qdisc_priv(dev_queue->qdisc); 225 struct neighbour *mn = skb_dst(skb)->neighbour; 226 struct neighbour *n = q->ncache; 227 228 if (mn->tbl == NULL) 229 return -EINVAL; 230 if (n && n->tbl == mn->tbl && 231 memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) { 232 atomic_inc(&n->refcnt); 233 } else { 234 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev); 235 if (IS_ERR(n)) 236 return PTR_ERR(n); 237 } 238 if (neigh_event_send(n, skb_res) == 0) { 239 int err; 240 241 read_lock(&n->lock); 242 err = dev_hard_header(skb, dev, ntohs(skb->protocol), 243 n->ha, NULL, skb->len); 244 read_unlock(&n->lock); 245 246 if (err < 0) { 247 neigh_release(n); 248 return -EINVAL; 249 } 250 teql_neigh_release(xchg(&q->ncache, n)); 251 return 0; 252 } 253 neigh_release(n); 254 return (skb_res == NULL) ? -EAGAIN : 1; 255 } 256 257 static inline int teql_resolve(struct sk_buff *skb, 258 struct sk_buff *skb_res, struct net_device *dev) 259 { 260 struct netdev_queue *txq = netdev_get_tx_queue(dev, 0); 261 if (txq->qdisc == &noop_qdisc) 262 return -ENODEV; 263 264 if (dev->header_ops == NULL || 265 skb_dst(skb) == NULL || 266 skb_dst(skb)->neighbour == NULL) 267 return 0; 268 return __teql_resolve(skb, skb_res, dev); 269 } 270 271 static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev) 272 { 273 struct teql_master *master = netdev_priv(dev); 274 struct netdev_queue *txq = netdev_get_tx_queue(dev, 0); 275 struct Qdisc *start, *q; 276 int busy; 277 int nores; 278 int subq = skb_get_queue_mapping(skb); 279 struct sk_buff *skb_res = NULL; 280 281 start = master->slaves; 282 283 restart: 284 nores = 0; 285 busy = 0; 286 287 if ((q = start) == NULL) 288 goto drop; 289 290 do { 291 struct net_device *slave = qdisc_dev(q); 292 struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0); 293 const struct net_device_ops *slave_ops = slave->netdev_ops; 294 295 if (slave_txq->qdisc_sleeping != q) 296 continue; 297 if (__netif_subqueue_stopped(slave, subq) || 298 !netif_running(slave)) { 299 busy = 1; 300 continue; 301 } 302 303 switch (teql_resolve(skb, skb_res, slave)) { 304 case 0: 305 if (__netif_tx_trylock(slave_txq)) { 306 unsigned int length = qdisc_pkt_len(skb); 307 308 if (!netif_tx_queue_stopped(slave_txq) && 309 !netif_tx_queue_frozen(slave_txq) && 310 slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) { 311 txq_trans_update(slave_txq); 312 __netif_tx_unlock(slave_txq); 313 master->slaves = NEXT_SLAVE(q); 314 netif_wake_queue(dev); 315 txq->tx_packets++; 316 txq->tx_bytes += length; 317 return NETDEV_TX_OK; 318 } 319 __netif_tx_unlock(slave_txq); 320 } 321 if (netif_queue_stopped(dev)) 322 busy = 1; 323 break; 324 case 1: 325 master->slaves = NEXT_SLAVE(q); 326 return NETDEV_TX_OK; 327 default: 328 nores = 1; 329 break; 330 } 331 __skb_pull(skb, skb_network_offset(skb)); 332 } while ((q = NEXT_SLAVE(q)) != start); 333 334 if (nores && skb_res == NULL) { 335 skb_res = skb; 336 goto restart; 337 } 338 339 if (busy) { 340 netif_stop_queue(dev); 341 return NETDEV_TX_BUSY; 342 } 343 dev->stats.tx_errors++; 344 345 drop: 346 txq->tx_dropped++; 347 dev_kfree_skb(skb); 348 return NETDEV_TX_OK; 349 } 350 351 static int teql_master_open(struct net_device *dev) 352 { 353 struct Qdisc * q; 354 struct teql_master *m = netdev_priv(dev); 355 int mtu = 0xFFFE; 356 unsigned flags = IFF_NOARP|IFF_MULTICAST; 357 358 if (m->slaves == NULL) 359 return -EUNATCH; 360 361 flags = FMASK; 362 363 q = m->slaves; 364 do { 365 struct net_device *slave = qdisc_dev(q); 366 367 if (slave == NULL) 368 return -EUNATCH; 369 370 if (slave->mtu < mtu) 371 mtu = slave->mtu; 372 if (slave->hard_header_len > LL_MAX_HEADER) 373 return -EINVAL; 374 375 /* If all the slaves are BROADCAST, master is BROADCAST 376 If all the slaves are PtP, master is PtP 377 Otherwise, master is NBMA. 378 */ 379 if (!(slave->flags&IFF_POINTOPOINT)) 380 flags &= ~IFF_POINTOPOINT; 381 if (!(slave->flags&IFF_BROADCAST)) 382 flags &= ~IFF_BROADCAST; 383 if (!(slave->flags&IFF_MULTICAST)) 384 flags &= ~IFF_MULTICAST; 385 } while ((q = NEXT_SLAVE(q)) != m->slaves); 386 387 m->dev->mtu = mtu; 388 m->dev->flags = (m->dev->flags&~FMASK) | flags; 389 netif_start_queue(m->dev); 390 return 0; 391 } 392 393 static int teql_master_close(struct net_device *dev) 394 { 395 netif_stop_queue(dev); 396 return 0; 397 } 398 399 static int teql_master_mtu(struct net_device *dev, int new_mtu) 400 { 401 struct teql_master *m = netdev_priv(dev); 402 struct Qdisc *q; 403 404 if (new_mtu < 68) 405 return -EINVAL; 406 407 q = m->slaves; 408 if (q) { 409 do { 410 if (new_mtu > qdisc_dev(q)->mtu) 411 return -EINVAL; 412 } while ((q=NEXT_SLAVE(q)) != m->slaves); 413 } 414 415 dev->mtu = new_mtu; 416 return 0; 417 } 418 419 static const struct net_device_ops teql_netdev_ops = { 420 .ndo_open = teql_master_open, 421 .ndo_stop = teql_master_close, 422 .ndo_start_xmit = teql_master_xmit, 423 .ndo_change_mtu = teql_master_mtu, 424 }; 425 426 static __init void teql_master_setup(struct net_device *dev) 427 { 428 struct teql_master *master = netdev_priv(dev); 429 struct Qdisc_ops *ops = &master->qops; 430 431 master->dev = dev; 432 ops->priv_size = sizeof(struct teql_sched_data); 433 434 ops->enqueue = teql_enqueue; 435 ops->dequeue = teql_dequeue; 436 ops->peek = teql_peek; 437 ops->init = teql_qdisc_init; 438 ops->reset = teql_reset; 439 ops->destroy = teql_destroy; 440 ops->owner = THIS_MODULE; 441 442 dev->netdev_ops = &teql_netdev_ops; 443 dev->type = ARPHRD_VOID; 444 dev->mtu = 1500; 445 dev->tx_queue_len = 100; 446 dev->flags = IFF_NOARP; 447 dev->hard_header_len = LL_MAX_HEADER; 448 } 449 450 static LIST_HEAD(master_dev_list); 451 static int max_equalizers = 1; 452 module_param(max_equalizers, int, 0); 453 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers"); 454 455 static int __init teql_init(void) 456 { 457 int i; 458 int err = -ENODEV; 459 460 for (i = 0; i < max_equalizers; i++) { 461 struct net_device *dev; 462 struct teql_master *master; 463 464 dev = alloc_netdev(sizeof(struct teql_master), 465 "teql%d", teql_master_setup); 466 if (!dev) { 467 err = -ENOMEM; 468 break; 469 } 470 471 if ((err = register_netdev(dev))) { 472 free_netdev(dev); 473 break; 474 } 475 476 master = netdev_priv(dev); 477 478 strlcpy(master->qops.id, dev->name, IFNAMSIZ); 479 err = register_qdisc(&master->qops); 480 481 if (err) { 482 unregister_netdev(dev); 483 free_netdev(dev); 484 break; 485 } 486 487 list_add_tail(&master->master_list, &master_dev_list); 488 } 489 return i ? 0 : err; 490 } 491 492 static void __exit teql_exit(void) 493 { 494 struct teql_master *master, *nxt; 495 496 list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) { 497 498 list_del(&master->master_list); 499 500 unregister_qdisc(&master->qops); 501 unregister_netdev(master->dev); 502 free_netdev(master->dev); 503 } 504 } 505 506 module_init(teql_init); 507 module_exit(teql_exit); 508 509 MODULE_LICENSE("GPL"); 510