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   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 <asm/uaccess.h>
  13 #include <asm/system.h>
  14 #include <linux/bitops.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/sched.h>
  18 #include <linux/string.h>
  19 #include <linux/mm.h>
  20 #include <linux/socket.h>
  21 #include <linux/sockios.h>
  22 #include <linux/in.h>
  23 #include <linux/errno.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/if_arp.h>
  26 #include <linux/if_ether.h>
  27 #include <linux/inet.h>
  28 #include <linux/netdevice.h>
  29 #include <linux/etherdevice.h>
  30 #include <linux/notifier.h>
  31 #include <linux/init.h>
  32 #include <net/ip.h>
  33 #include <net/route.h>
  34 #include <linux/skbuff.h>
  35 #include <linux/moduleparam.h>
  36 #include <net/sock.h>
  37 #include <net/pkt_sched.h>
  38
  39 /*
  40    How to setup it.
  41    ----------------
  42
  43    After loading this module you will find a new device teqlN
  44    and new qdisc with the same name. To join a slave to the equalizer
  45    you should just set this qdisc on a device f.e.
  46
  47    # tc qdisc add dev eth0 root teql0
  48    # tc qdisc add dev eth1 root teql0
  49
  50    That's all. Full PnP 8)
  51
  52    Applicability.
  53    --------------
  54
  55    1. Slave devices MUST be active devices, i.e., they must raise the tbusy
  56       signal and generate EOI events. If you want to equalize virtual devices
  57       like tunnels, use a normal eql device.
  58    2. This device puts no limitations on physical slave characteristics
  59       f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-)
  60       Certainly, large difference in link speeds will make the resulting
  61       eqalized link unusable, because of huge packet reordering.
  62       I estimate an upper useful difference as ~10 times.
  63    3. If the slave requires address resolution, only protocols using
  64       neighbour cache (IPv4/IPv6) will work over the equalized link.
  65       Other protocols are still allowed to use the slave device directly,
  66       which will not break load balancing, though native slave
  67       traffic will have the highest priority.  */
  68
  69 struct teql_master
  70 {
  71         struct Qdisc_ops qops;
  72         struct net_device *dev;
  73         struct Qdisc *slaves;
  74         struct list_head master_list;
  75         struct net_device_stats stats;
  76 };
  77
  78 struct teql_sched_data
  79 {
  80         struct Qdisc *next;
  81         struct teql_master *m;
  82         struct neighbour *ncache;
  83         struct sk_buff_head q;
  84 };
  85
  86 #define NEXT_SLAVE(q) (((struct teql_sched_data*)qdisc_priv(q))->next)
  87
  88 #define FMASK (IFF_BROADCAST|IFF_POINTOPOINT|IFF_BROADCAST)
  89
  90 /* "teql*" qdisc routines */
  91
  92 static int
  93 teql_enqueue(struct sk_buff *skb, struct Qdisc* sch)
  94 {
  95         struct net_device *dev = sch->dev;
  96         struct teql_sched_data *q = qdisc_priv(sch);
  97
  98         __skb_queue_tail(&q->q, skb);
  99         if (q->q.qlen <= dev->tx_queue_len) {
 100                 sch->bstats.bytes += skb->len;
 101                 sch->bstats.packets++;
 102                 return 0;
 103         }
 104
 105         __skb_unlink(skb, &q->q);
 106         kfree_skb(skb);
 107         sch->qstats.drops++;
 108         return NET_XMIT_DROP;
 109 }
 110
 111 static int
 112 teql_requeue(struct sk_buff *skb, struct Qdisc* sch)
 113 {
 114         struct teql_sched_data *q = qdisc_priv(sch);
 115
 116         __skb_queue_head(&q->q, skb);
 117         sch->qstats.requeues++;
 118         return 0;
 119 }
 120
 121 static struct sk_buff *
 122 teql_dequeue(struct Qdisc* sch)
 123 {
 124         struct teql_sched_data *dat = qdisc_priv(sch);
 125         struct sk_buff *skb;
 126
 127         skb = __skb_dequeue(&dat->q);
 128         if (skb == NULL) {
 129                 struct net_device *m = dat->m->dev->qdisc->dev;
 130                 if (m) {
 131                         dat->m->slaves = sch;
 132                         netif_wake_queue(m);
 133                 }
 134         }
 135         sch->q.qlen = dat->q.qlen + dat->m->dev->qdisc->q.qlen;
 136         return skb;
 137 }
 138
 139 static __inline__ void
 140 teql_neigh_release(struct neighbour *n)
 141 {
 142         if (n)
 143                 neigh_release(n);
 144 }
 145
 146 static void
 147 teql_reset(struct Qdisc* sch)
 148 {
 149         struct teql_sched_data *dat = qdisc_priv(sch);
 150
 151         skb_queue_purge(&dat->q);
 152         sch->q.qlen = 0;
 153         teql_neigh_release(xchg(&dat->ncache, NULL));
 154 }
 155
 156 static void
 157 teql_destroy(struct Qdisc* sch)
 158 {
 159         struct Qdisc *q, *prev;
 160         struct teql_sched_data *dat = qdisc_priv(sch);
 161         struct teql_master *master = dat->m;
 162
 163         if ((prev = master->slaves) != NULL) {
 164                 do {
 165                         q = NEXT_SLAVE(prev);
 166                         if (q == sch) {
 167                                 NEXT_SLAVE(prev) = NEXT_SLAVE(q);
 168                                 if (q == master->slaves) {
 169                                         master->slaves = NEXT_SLAVE(q);
 170                                         if (q == master->slaves) {
 171                                                 master->slaves = NULL;
 172                                                 spin_lock_bh(&master->dev->queue_lock);
 173                                                 qdisc_reset(master->dev->qdisc);
 174                                                 spin_unlock_bh(&master->dev->queue_lock);
 175                                         }
 176                                 }
 177                                 skb_queue_purge(&dat->q);
 178                                 teql_neigh_release(xchg(&dat->ncache, NULL));
 179                                 break;
 180                         }
 181
 182                 } while ((prev = q) != master->slaves);
 183         }
 184 }
 185
 186 static int teql_qdisc_init(struct Qdisc *sch, struct rtattr *opt)
 187 {
 188         struct net_device *dev = sch->dev;
 189         struct teql_master *m = (struct teql_master*)sch->ops;
 190         struct teql_sched_data *q = qdisc_priv(sch);
 191
 192         if (dev->hard_header_len > m->dev->hard_header_len)
 193                 return -EINVAL;
 194
 195         if (m->dev == dev)
 196                 return -ELOOP;
 197
 198         q->m = m;
 199
 200         skb_queue_head_init(&q->q);
 201
 202         if (m->slaves) {
 203                 if (m->dev->flags & IFF_UP) {
 204                         if ((m->dev->flags&IFF_POINTOPOINT && !(dev->flags&IFF_POINTOPOINT))
 205                             || (m->dev->flags&IFF_BROADCAST && !(dev->flags&IFF_BROADCAST))
 206                             || (m->dev->flags&IFF_MULTICAST && !(dev->flags&IFF_MULTICAST))
 207                             || dev->mtu < m->dev->mtu)
 208                                 return -EINVAL;
 209                 } else {
 210                         if (!(dev->flags&IFF_POINTOPOINT))
 211                                 m->dev->flags &= ~IFF_POINTOPOINT;
 212                         if (!(dev->flags&IFF_BROADCAST))
 213                                 m->dev->flags &= ~IFF_BROADCAST;
 214                         if (!(dev->flags&IFF_MULTICAST))
 215                                 m->dev->flags &= ~IFF_MULTICAST;
 216                         if (dev->mtu < m->dev->mtu)
 217                                 m->dev->mtu = dev->mtu;
 218                 }
 219                 q->next = NEXT_SLAVE(m->slaves);
 220                 NEXT_SLAVE(m->slaves) = sch;
 221         } else {
 222                 q->next = sch;
 223                 m->slaves = sch;
 224                 m->dev->mtu = dev->mtu;
 225                 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK);
 226         }
 227         return 0;
 228 }
 229
 230 /* "teql*" netdevice routines */
 231
 232 static int
 233 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
 234 {
 235         struct teql_sched_data *q = qdisc_priv(dev->qdisc);
 236         struct neighbour *mn = skb->dst->neighbour;
 237         struct neighbour *n = q->ncache;
 238
 239         if (mn->tbl == NULL)
 240                 return -EINVAL;
 241         if (n && n->tbl == mn->tbl &&
 242             memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) {
 243                 atomic_inc(&n->refcnt);
 244         } else {
 245                 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev);
 246                 if (IS_ERR(n))
 247                         return PTR_ERR(n);
 248         }
 249         if (neigh_event_send(n, skb_res) == 0) {
 250                 int err;
 251                 read_lock(&n->lock);
 252                 err = dev->hard_header(skb, dev, ntohs(skb->protocol), n->ha, NULL, skb->len);
 253                 read_unlock(&n->lock);
 254                 if (err < 0) {
 255                         neigh_release(n);
 256                         return -EINVAL;
 257                 }
 258                 teql_neigh_release(xchg(&q->ncache, n));
 259                 return 0;
 260         }
 261         neigh_release(n);
 262         return (skb_res == NULL) ? -EAGAIN : 1;
 263 }
 264
 265 static __inline__ int
 266 teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
 267 {
 268         if (dev->hard_header == NULL ||
 269             skb->dst == NULL ||
 270             skb->dst->neighbour == NULL)
 271                 return 0;
 272         return __teql_resolve(skb, skb_res, dev);
 273 }
 274
 275 static int teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
 276 {
 277         struct teql_master *master = netdev_priv(dev);
 278         struct Qdisc *start, *q;
 279         int busy;
 280         int nores;
 281         int len = skb->len;
 282         struct sk_buff *skb_res = NULL;
 283
 284         start = master->slaves;
 285
 286 restart:
 287         nores = 0;
 288         busy = 0;
 289
 290         if ((q = start) == NULL)
 291                 goto drop;
 292
 293         do {
 294                 struct net_device *slave = q->dev;
 295
 296                 if (slave->qdisc_sleeping != q)
 297                         continue;
 298                 if (netif_queue_stopped(slave) || ! 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)) {
 306                                 if (!netif_queue_stopped(slave) &&
 307                                     slave->hard_start_xmit(skb, slave) == 0) {
 308                                         netif_tx_unlock(slave);
 309                                         master->slaves = NEXT_SLAVE(q);
 310                                         netif_wake_queue(dev);
 311                                         master->stats.tx_packets++;
 312                                         master->stats.tx_bytes += len;
 313                                         return 0;
 314                                 }
 315                                 netif_tx_unlock(slave);
 316                         }
 317                         if (netif_queue_stopped(dev))
 318                                 busy = 1;
 319                         break;
 320                 case 1:
 321                         master->slaves = NEXT_SLAVE(q);
 322                         return 0;
 323                 default:
 324                         nores = 1;
 325                         break;
 326                 }
 327                 __skb_pull(skb, skb->nh.raw - skb->data);
 328         } while ((q = NEXT_SLAVE(q)) != start);
 329
 330         if (nores && skb_res == NULL) {
 331                 skb_res = skb;
 332                 goto restart;
 333         }
 334
 335         if (busy) {
 336                 netif_stop_queue(dev);
 337                 return 1;
 338         }
 339         master->stats.tx_errors++;
 340
 341 drop:
 342         master->stats.tx_dropped++;
 343         dev_kfree_skb(skb);
 344         return 0;
 345 }
 346
 347 static int teql_master_open(struct net_device *dev)
 348 {
 349         struct Qdisc * q;
 350         struct teql_master *m = netdev_priv(dev);
 351         int mtu = 0xFFFE;
 352         unsigned flags = IFF_NOARP|IFF_MULTICAST;
 353
 354         if (m->slaves == NULL)
 355                 return -EUNATCH;
 356
 357         flags = FMASK;
 358
 359         q = m->slaves;
 360         do {
 361                 struct net_device *slave = q->dev;
 362
 363                 if (slave == NULL)
 364                         return -EUNATCH;
 365
 366                 if (slave->mtu < mtu)
 367                         mtu = slave->mtu;
 368                 if (slave->hard_header_len > LL_MAX_HEADER)
 369                         return -EINVAL;
 370
 371                 /* If all the slaves are BROADCAST, master is BROADCAST
 372                    If all the slaves are PtP, master is PtP
 373                    Otherwise, master is NBMA.
 374                  */
 375                 if (!(slave->flags&IFF_POINTOPOINT))
 376                         flags &= ~IFF_POINTOPOINT;
 377                 if (!(slave->flags&IFF_BROADCAST))
 378                         flags &= ~IFF_BROADCAST;
 379                 if (!(slave->flags&IFF_MULTICAST))
 380                         flags &= ~IFF_MULTICAST;
 381         } while ((q = NEXT_SLAVE(q)) != m->slaves);
 382
 383         m->dev->mtu = mtu;
 384         m->dev->flags = (m->dev->flags&~FMASK) | flags;
 385         netif_start_queue(m->dev);
 386         return 0;
 387 }
 388
 389 static int teql_master_close(struct net_device *dev)
 390 {
 391         netif_stop_queue(dev);
 392         return 0;
 393 }
 394
 395 static struct net_device_stats *teql_master_stats(struct net_device *dev)
 396 {
 397         struct teql_master *m = netdev_priv(dev);
 398         return &m->stats;
 399 }
 400
 401 static int teql_master_mtu(struct net_device *dev, int new_mtu)
 402 {
 403         struct teql_master *m = netdev_priv(dev);
 404         struct Qdisc *q;
 405
 406         if (new_mtu < 68)
 407                 return -EINVAL;
 408
 409         q = m->slaves;
 410         if (q) {
 411                 do {
 412                         if (new_mtu > q->dev->mtu)
 413                                 return -EINVAL;
 414                 } while ((q=NEXT_SLAVE(q)) != m->slaves);
 415         }
 416
 417         dev->mtu = new_mtu;
 418         return 0;
 419 }
 420
 421 static __init void teql_master_setup(struct net_device *dev)
 422 {
 423         struct teql_master *master = netdev_priv(dev);
 424         struct Qdisc_ops *ops = &master->qops;
 425
 426         master->dev     = dev;
 427         ops->priv_size  = sizeof(struct teql_sched_data);
 428
 429         ops->enqueue    =       teql_enqueue;
 430         ops->dequeue    =       teql_dequeue;
 431         ops->requeue    =       teql_requeue;
 432         ops->init       =       teql_qdisc_init;
 433         ops->reset      =       teql_reset;
 434         ops->destroy    =       teql_destroy;
 435         ops->owner      =       THIS_MODULE;
 436
 437         dev->open               = teql_master_open;
 438         dev->hard_start_xmit    = teql_master_xmit;
 439         dev->stop               = teql_master_close;
 440         dev->get_stats          = teql_master_stats;
 441         dev->change_mtu         = teql_master_mtu;
 442         dev->type               = ARPHRD_VOID;
 443         dev->mtu                = 1500;
 444         dev->tx_queue_len       = 100;
 445         dev->flags              = IFF_NOARP;
 446         dev->hard_header_len    = LL_MAX_HEADER;
 447         SET_MODULE_OWNER(dev);
 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");