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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 (spin_trylock(&slave->xmit_lock)) {
 306                                 slave->xmit_lock_owner = smp_processor_id();
 307                                 if (!netif_queue_stopped(slave) &&
 308                                     slave->hard_start_xmit(skb, slave) == 0) {
 309                                         slave->xmit_lock_owner = -1;
 310                                         spin_unlock(&slave->xmit_lock);
 311                                         master->slaves = NEXT_SLAVE(q);
 312                                         netif_wake_queue(dev);
 313                                         master->stats.tx_packets++;
 314                                         master->stats.tx_bytes += len;
 315                                         return 0;
 316                                 }
 317                                 slave->xmit_lock_owner = -1;
 318                                 spin_unlock(&slave->xmit_lock);
 319                         }
 320                         if (netif_queue_stopped(dev))
 321                                 busy = 1;
 322                         break;
 323                 case 1:
 324                         master->slaves = NEXT_SLAVE(q);
 325                         return 0;
 326                 default:
 327                         nores = 1;
 328                         break;
 329                 }
 330                 __skb_pull(skb, skb->nh.raw - skb->data);
 331         } while ((q = NEXT_SLAVE(q)) != start);
 332
 333         if (nores && skb_res == NULL) {
 334                 skb_res = skb;
 335                 goto restart;
 336         }
 337
 338         if (busy) {
 339                 netif_stop_queue(dev);
 340                 return 1;
 341         }
 342         master->stats.tx_errors++;
 343
 344 drop:
 345         master->stats.tx_dropped++;
 346         dev_kfree_skb(skb);
 347         return 0;
 348 }
 349
 350 static int teql_master_open(struct net_device *dev)
 351 {
 352         struct Qdisc * q;
 353         struct teql_master *m = netdev_priv(dev);
 354         int mtu = 0xFFFE;
 355         unsigned flags = IFF_NOARP|IFF_MULTICAST;
 356
 357         if (m->slaves == NULL)
 358                 return -EUNATCH;
 359
 360         flags = FMASK;
 361
 362         q = m->slaves;
 363         do {
 364                 struct net_device *slave = q->dev;
 365
 366                 if (slave == NULL)
 367                         return -EUNATCH;
 368
 369                 if (slave->mtu < mtu)
 370                         mtu = slave->mtu;
 371                 if (slave->hard_header_len > LL_MAX_HEADER)
 372                         return -EINVAL;
 373
 374                 /* If all the slaves are BROADCAST, master is BROADCAST
 375                    If all the slaves are PtP, master is PtP
 376                    Otherwise, master is NBMA.
 377                  */
 378                 if (!(slave->flags&IFF_POINTOPOINT))
 379                         flags &= ~IFF_POINTOPOINT;
 380                 if (!(slave->flags&IFF_BROADCAST))
 381                         flags &= ~IFF_BROADCAST;
 382                 if (!(slave->flags&IFF_MULTICAST))
 383                         flags &= ~IFF_MULTICAST;
 384         } while ((q = NEXT_SLAVE(q)) != m->slaves);
 385
 386         m->dev->mtu = mtu;
 387         m->dev->flags = (m->dev->flags&~FMASK) | flags;
 388         netif_start_queue(m->dev);
 389         return 0;
 390 }
 391
 392 static int teql_master_close(struct net_device *dev)
 393 {
 394         netif_stop_queue(dev);
 395         return 0;
 396 }
 397
 398 static struct net_device_stats *teql_master_stats(struct net_device *dev)
 399 {
 400         struct teql_master *m = netdev_priv(dev);
 401         return &m->stats;
 402 }
 403
 404 static int teql_master_mtu(struct net_device *dev, int new_mtu)
 405 {
 406         struct teql_master *m = netdev_priv(dev);
 407         struct Qdisc *q;
 408
 409         if (new_mtu < 68)
 410                 return -EINVAL;
 411
 412         q = m->slaves;
 413         if (q) {
 414                 do {
 415                         if (new_mtu > q->dev->mtu)
 416                                 return -EINVAL;
 417                 } while ((q=NEXT_SLAVE(q)) != m->slaves);
 418         }
 419
 420         dev->mtu = new_mtu;
 421         return 0;
 422 }
 423
 424 static __init void teql_master_setup(struct net_device *dev)
 425 {
 426         struct teql_master *master = netdev_priv(dev);
 427         struct Qdisc_ops *ops = &master->qops;
 428
 429         master->dev     = dev;
 430         ops->priv_size  = sizeof(struct teql_sched_data);
 431
 432         ops->enqueue    =       teql_enqueue;
 433         ops->dequeue    =       teql_dequeue;
 434         ops->requeue    =       teql_requeue;
 435         ops->init       =       teql_qdisc_init;
 436         ops->reset      =       teql_reset;
 437         ops->destroy    =       teql_destroy;
 438         ops->owner      =       THIS_MODULE;
 439
 440         dev->open               = teql_master_open;
 441         dev->hard_start_xmit    = teql_master_xmit;
 442         dev->stop               = teql_master_close;
 443         dev->get_stats          = teql_master_stats;
 444         dev->change_mtu         = teql_master_mtu;
 445         dev->type               = ARPHRD_VOID;
 446         dev->mtu                = 1500;
 447         dev->tx_queue_len       = 100;
 448         dev->flags              = IFF_NOARP;
 449         dev->hard_header_len    = LL_MAX_HEADER;
 450         SET_MODULE_OWNER(dev);
 451 }
 452
 453 static LIST_HEAD(master_dev_list);
 454 static int max_equalizers = 1;
 455 module_param(max_equalizers, int, 0);
 456 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers");
 457
 458 static int __init teql_init(void)
 459 {
 460         int i;
 461         int err = -ENODEV;
 462
 463         for (i = 0; i < max_equalizers; i++) {
 464                 struct net_device *dev;
 465                 struct teql_master *master;
 466
 467                 dev = alloc_netdev(sizeof(struct teql_master),
 468                                   "teql%d", teql_master_setup);
 469                 if (!dev) {
 470                         err = -ENOMEM;
 471                         break;
 472                 }
 473
 474                 if ((err = register_netdev(dev))) {
 475                         free_netdev(dev);
 476                         break;
 477                 }
 478
 479                 master = netdev_priv(dev);
 480
 481                 strlcpy(master->qops.id, dev->name, IFNAMSIZ);
 482                 err = register_qdisc(&master->qops);
 483
 484                 if (err) {
 485                         unregister_netdev(dev);
 486                         free_netdev(dev);
 487                         break;
 488                 }
 489
 490                 list_add_tail(&master->master_list, &master_dev_list);
 491         }
 492         return i ? 0 : err;
 493 }
 494
 495 static void __exit teql_exit(void)
 496 {
 497         struct teql_master *master, *nxt;
 498
 499         list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) {
 500
 501                 list_del(&master->master_list);
 502
 503                 unregister_qdisc(&master->qops);
 504                 unregister_netdev(master->dev);
 505                 free_netdev(master->dev);
 506         }
 507 }
 508
 509 module_init(teql_init);
 510 module_exit(teql_exit);
 511
 512 MODULE_LICENSE("GPL");