net/sched/sch_teql.c

   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/string.h>
  18 #include <linux/mm.h>
  19 #include <linux/socket.h>
  20 #include <linux/sockios.h>
  21 #include <linux/in.h>
  22 #include <linux/errno.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/if_arp.h>
  25 #include <linux/if_ether.h>
  26 #include <linux/inet.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/etherdevice.h>
  29 #include <linux/notifier.h>
  30 #include <linux/init.h>
  31 #include <net/ip.h>
  32 #include <net/route.h>
  33 #include <linux/skbuff.h>
  34 #include <linux/moduleparam.h>
  35 #include <net/sock.h>
  36 #include <net/pkt_sched.h>
  37
  38 /*
  39    How to setup it.
  40    ----------------
  41
  42    After loading this module you will find a new device teqlN
  43    and new qdisc with the same name. To join a slave to the equalizer
  44    you should just set this qdisc on a device f.e.
  45
  46    # tc qdisc add dev eth0 root teql0
  47    # tc qdisc add dev eth1 root teql0
  48
  49    That's all. Full PnP 8)
  50
  51    Applicability.
  52    --------------
  53
  54    1. Slave devices MUST be active devices, i.e., they must raise the tbusy
  55       signal and generate EOI events. If you want to equalize virtual devices
  56       like tunnels, use a normal eql device.
  57    2. This device puts no limitations on physical slave characteristics
  58       f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-)
  59       Certainly, large difference in link speeds will make the resulting
  60       eqalized link unusable, because of huge packet reordering.
  61       I estimate an upper useful difference as ~10 times.
  62    3. If the slave requires address resolution, only protocols using
  63       neighbour cache (IPv4/IPv6) will work over the equalized link.
  64       Other protocols are still allowed to use the slave device directly,
  65       which will not break load balancing, though native slave
  66       traffic will have the highest priority.  */
  67
  68 struct teql_master
  69 {
  70         struct Qdisc_ops qops;
  71         struct net_device *dev;
  72         struct Qdisc *slaves;
  73         struct list_head master_list;
  74         struct net_device_stats stats;
  75 };
  76
  77 struct teql_sched_data
  78 {
  79         struct Qdisc *next;
  80         struct teql_master *m;
  81         struct neighbour *ncache;
  82         struct sk_buff_head q;
  83 };
  84
  85 #define NEXT_SLAVE(q) (((struct teql_sched_data*)qdisc_priv(q))->next)
  86
  87 #define FMASK (IFF_BROADCAST|IFF_POINTOPOINT|IFF_BROADCAST)
  88
  89 /* "teql*" qdisc routines */
  90
  91 static int
  92 teql_enqueue(struct sk_buff *skb, struct Qdisc* sch)
  93 {
  94         struct net_device *dev = sch->dev;
  95         struct teql_sched_data *q = qdisc_priv(sch);
  96
  97         if (q->q.qlen < dev->tx_queue_len) {
  98                 __skb_queue_tail(&q->q, skb);
  99                 sch->bstats.bytes += skb->len;
 100                 sch->bstats.packets++;
 101                 return 0;
 102         }
 103
 104         kfree_skb(skb);
 105         sch->qstats.drops++;
 106         return NET_XMIT_DROP;
 107 }
 108
 109 static int
 110 teql_requeue(struct sk_buff *skb, struct Qdisc* sch)
 111 {
 112         struct teql_sched_data *q = qdisc_priv(sch);
 113
 114         __skb_queue_head(&q->q, skb);
 115         sch->qstats.requeues++;
 116         return 0;
 117 }
 118
 119 static struct sk_buff *
 120 teql_dequeue(struct Qdisc* sch)
 121 {
 122         struct teql_sched_data *dat = qdisc_priv(sch);
 123         struct sk_buff *skb;
 124
 125         skb = __skb_dequeue(&dat->q);
 126         if (skb == NULL) {
 127                 struct net_device *m = dat->m->dev->qdisc->dev;
 128                 if (m) {
 129                         dat->m->slaves = sch;
 130                         netif_wake_queue(m);
 131                 }
 132         }
 133         sch->q.qlen = dat->q.qlen + dat->m->dev->qdisc->q.qlen;
 134         return skb;
 135 }
 136
 137 static __inline__ void
 138 teql_neigh_release(struct neighbour *n)
 139 {
 140         if (n)
 141                 neigh_release(n);
 142 }
 143
 144 static void
 145 teql_reset(struct Qdisc* sch)
 146 {
 147         struct teql_sched_data *dat = qdisc_priv(sch);
 148
 149         skb_queue_purge(&dat->q);
 150         sch->q.qlen = 0;
 151         teql_neigh_release(xchg(&dat->ncache, NULL));
 152 }
 153
 154 static void
 155 teql_destroy(struct Qdisc* sch)
 156 {
 157         struct Qdisc *q, *prev;
 158         struct teql_sched_data *dat = qdisc_priv(sch);
 159         struct teql_master *master = dat->m;
 160
 161         if ((prev = master->slaves) != NULL) {
 162                 do {
 163                         q = NEXT_SLAVE(prev);
 164                         if (q == sch) {
 165                                 NEXT_SLAVE(prev) = NEXT_SLAVE(q);
 166                                 if (q == master->slaves) {
 167                                         master->slaves = NEXT_SLAVE(q);
 168                                         if (q == master->slaves) {
 169                                                 master->slaves = NULL;
 170                                                 spin_lock_bh(&master->dev->queue_lock);
 171                                                 qdisc_reset(master->dev->qdisc);
 172                                                 spin_unlock_bh(&master->dev->queue_lock);
 173                                         }
 174                                 }
 175                                 skb_queue_purge(&dat->q);
 176                                 teql_neigh_release(xchg(&dat->ncache, NULL));
 177                                 break;
 178                         }
 179
 180                 } while ((prev = q) != master->slaves);
 181         }
 182 }
 183
 184 static int teql_qdisc_init(struct Qdisc *sch, struct rtattr *opt)
 185 {
 186         struct net_device *dev = sch->dev;
 187         struct teql_master *m = (struct teql_master*)sch->ops;
 188         struct teql_sched_data *q = qdisc_priv(sch);
 189
 190         if (dev->hard_header_len > m->dev->hard_header_len)
 191                 return -EINVAL;
 192
 193         if (m->dev == dev)
 194                 return -ELOOP;
 195
 196         q->m = m;
 197
 198         skb_queue_head_init(&q->q);
 199
 200         if (m->slaves) {
 201                 if (m->dev->flags & IFF_UP) {
 202                         if ((m->dev->flags&IFF_POINTOPOINT && !(dev->flags&IFF_POINTOPOINT))
 203                             || (m->dev->flags&IFF_BROADCAST && !(dev->flags&IFF_BROADCAST))
 204                             || (m->dev->flags&IFF_MULTICAST && !(dev->flags&IFF_MULTICAST))
 205                             || dev->mtu < m->dev->mtu)
 206                                 return -EINVAL;
 207                 } else {
 208                         if (!(dev->flags&IFF_POINTOPOINT))
 209                                 m->dev->flags &= ~IFF_POINTOPOINT;
 210                         if (!(dev->flags&IFF_BROADCAST))
 211                                 m->dev->flags &= ~IFF_BROADCAST;
 212                         if (!(dev->flags&IFF_MULTICAST))
 213                                 m->dev->flags &= ~IFF_MULTICAST;
 214                         if (dev->mtu < m->dev->mtu)
 215                                 m->dev->mtu = dev->mtu;
 216                 }
 217                 q->next = NEXT_SLAVE(m->slaves);
 218                 NEXT_SLAVE(m->slaves) = sch;
 219         } else {
 220                 q->next = sch;
 221                 m->slaves = sch;
 222                 m->dev->mtu = dev->mtu;
 223                 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK);
 224         }
 225         return 0;
 226 }
 227
 228 /* "teql*" netdevice routines */
 229
 230 static int
 231 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
 232 {
 233         struct teql_sched_data *q = qdisc_priv(dev->qdisc);
 234         struct neighbour *mn = skb->dst->neighbour;
 235         struct neighbour *n = q->ncache;
 236
 237         if (mn->tbl == NULL)
 238                 return -EINVAL;
 239         if (n && n->tbl == mn->tbl &&
 240             memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) {
 241                 atomic_inc(&n->refcnt);
 242         } else {
 243                 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev);
 244                 if (IS_ERR(n))
 245                         return PTR_ERR(n);
 246         }
 247         if (neigh_event_send(n, skb_res) == 0) {
 248                 int err;
 249                 read_lock(&n->lock);
 250                 err = dev->hard_header(skb, dev, ntohs(skb->protocol), n->ha, NULL, skb->len);
 251                 read_unlock(&n->lock);
 252                 if (err < 0) {
 253                         neigh_release(n);
 254                         return -EINVAL;
 255                 }
 256                 teql_neigh_release(xchg(&q->ncache, n));
 257                 return 0;
 258         }
 259         neigh_release(n);
 260         return (skb_res == NULL) ? -EAGAIN : 1;
 261 }
 262
 263 static __inline__ int
 264 teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
 265 {
 266         if (dev->hard_header == NULL ||
 267             skb->dst == NULL ||
 268             skb->dst->neighbour == NULL)
 269                 return 0;
 270         return __teql_resolve(skb, skb_res, dev);
 271 }
 272
 273 static int teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
 274 {
 275         struct teql_master *master = netdev_priv(dev);
 276         struct Qdisc *start, *q;
 277         int busy;
 278         int nores;
 279         int len = skb->len;
 280         int subq = skb->queue_mapping;
 281         struct sk_buff *skb_res = NULL;
 282
 283         start = master->slaves;
 284
 285 restart:
 286         nores = 0;
 287         busy = 0;
 288
 289         if ((q = start) == NULL)
 290                 goto drop;
 291
 292         do {
 293                 struct net_device *slave = q->dev;
 294
 295                 if (slave->qdisc_sleeping != q)
 296                         continue;
 297                 if (netif_queue_stopped(slave) ||
 298                     netif_subqueue_stopped(slave, subq) ||
 299                     !netif_running(slave)) {
 300                         busy = 1;
 301                         continue;
 302                 }
 303
 304                 switch (teql_resolve(skb, skb_res, slave)) {
 305                 case 0:
 306                         if (netif_tx_trylock(slave)) {
 307                                 if (!netif_queue_stopped(slave) &&
 308                                     !netif_subqueue_stopped(slave, subq) &&
 309                                     slave->hard_start_xmit(skb, slave) == 0) {
 310                                         netif_tx_unlock(slave);
 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                                 netif_tx_unlock(slave);
 318                         }
 319                         if (netif_queue_stopped(dev))
 320                                 busy = 1;
 321                         break;
 322                 case 1:
 323                         master->slaves = NEXT_SLAVE(q);
 324                         return 0;
 325                 default:
 326                         nores = 1;
 327                         break;
 328                 }
 329                 __skb_pull(skb, skb_network_offset(skb));
 330         } while ((q = NEXT_SLAVE(q)) != start);
 331
 332         if (nores && skb_res == NULL) {
 333                 skb_res = skb;
 334                 goto restart;
 335         }
 336
 337         if (busy) {
 338                 netif_stop_queue(dev);
 339                 return 1;
 340         }
 341         master->stats.tx_errors++;
 342
 343 drop:
 344         master->stats.tx_dropped++;
 345         dev_kfree_skb(skb);
 346         return 0;
 347 }
 348
 349 static int teql_master_open(struct net_device *dev)
 350 {
 351         struct Qdisc * q;
 352         struct teql_master *m = netdev_priv(dev);
 353         int mtu = 0xFFFE;
 354         unsigned flags = IFF_NOARP|IFF_MULTICAST;
 355
 356         if (m->slaves == NULL)
 357                 return -EUNATCH;
 358
 359         flags = FMASK;
 360
 361         q = m->slaves;
 362         do {
 363                 struct net_device *slave = q->dev;
 364
 365                 if (slave == NULL)
 366                         return -EUNATCH;
 367
 368                 if (slave->mtu < mtu)
 369                         mtu = slave->mtu;
 370                 if (slave->hard_header_len > LL_MAX_HEADER)
 371                         return -EINVAL;
 372
 373                 /* If all the slaves are BROADCAST, master is BROADCAST
 374                    If all the slaves are PtP, master is PtP
 375                    Otherwise, master is NBMA.
 376                  */
 377                 if (!(slave->flags&IFF_POINTOPOINT))
 378                         flags &= ~IFF_POINTOPOINT;
 379                 if (!(slave->flags&IFF_BROADCAST))
 380                         flags &= ~IFF_BROADCAST;
 381                 if (!(slave->flags&IFF_MULTICAST))
 382                         flags &= ~IFF_MULTICAST;
 383         } while ((q = NEXT_SLAVE(q)) != m->slaves);
 384
 385         m->dev->mtu = mtu;
 386         m->dev->flags = (m->dev->flags&~FMASK) | flags;
 387         netif_start_queue(m->dev);
 388         return 0;
 389 }
 390
 391 static int teql_master_close(struct net_device *dev)
 392 {
 393         netif_stop_queue(dev);
 394         return 0;
 395 }
 396
 397 static struct net_device_stats *teql_master_stats(struct net_device *dev)
 398 {
 399         struct teql_master *m = netdev_priv(dev);
 400         return &m->stats;
 401 }
 402
 403 static int teql_master_mtu(struct net_device *dev, int new_mtu)
 404 {
 405         struct teql_master *m = netdev_priv(dev);
 406         struct Qdisc *q;
 407
 408         if (new_mtu < 68)
 409                 return -EINVAL;
 410
 411         q = m->slaves;
 412         if (q) {
 413                 do {
 414                         if (new_mtu > q->dev->mtu)
 415                                 return -EINVAL;
 416                 } while ((q=NEXT_SLAVE(q)) != m->slaves);
 417         }
 418
 419         dev->mtu = new_mtu;
 420         return 0;
 421 }
 422
 423 static __init void teql_master_setup(struct net_device *dev)
 424 {
 425         struct teql_master *master = netdev_priv(dev);
 426         struct Qdisc_ops *ops = &master->qops;
 427
 428         master->dev     = dev;
 429         ops->priv_size  = sizeof(struct teql_sched_data);
 430
 431         ops->enqueue    =       teql_enqueue;
 432         ops->dequeue    =       teql_dequeue;
 433         ops->requeue    =       teql_requeue;
 434         ops->init       =       teql_qdisc_init;
 435         ops->reset      =       teql_reset;
 436         ops->destroy    =       teql_destroy;
 437         ops->owner      =       THIS_MODULE;
 438
 439         dev->open               = teql_master_open;
 440         dev->hard_start_xmit    = teql_master_xmit;
 441         dev->stop               = teql_master_close;
 442         dev->get_stats          = teql_master_stats;
 443         dev->change_mtu         = teql_master_mtu;
 444         dev->type               = ARPHRD_VOID;
 445         dev->mtu                = 1500;
 446         dev->tx_queue_len       = 100;
 447         dev->flags              = IFF_NOARP;
 448         dev->hard_header_len    = LL_MAX_HEADER;
 449         SET_MODULE_OWNER(dev);
 450 }
 451
 452 static LIST_HEAD(master_dev_list);
 453 static int max_equalizers = 1;
 454 module_param(max_equalizers, int, 0);
 455 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers");
 456
 457 static int __init teql_init(void)
 458 {
 459         int i;
 460         int err = -ENODEV;
 461
 462         for (i = 0; i < max_equalizers; i++) {
 463                 struct net_device *dev;
 464                 struct teql_master *master;
 465
 466                 dev = alloc_netdev(sizeof(struct teql_master),
 467                                   "teql%d", teql_master_setup);
 468                 if (!dev) {
 469                         err = -ENOMEM;
 470                         break;
 471                 }
 472
 473                 if ((err = register_netdev(dev))) {
 474                         free_netdev(dev);
 475                         break;
 476                 }
 477
 478                 master = netdev_priv(dev);
 479
 480                 strlcpy(master->qops.id, dev->name, IFNAMSIZ);
 481                 err = register_qdisc(&master->qops);
 482
 483                 if (err) {
 484                         unregister_netdev(dev);
 485                         free_netdev(dev);
 486                         break;
 487                 }
 488
 489                 list_add_tail(&master->master_list, &master_dev_list);
 490         }
 491         return i ? 0 : err;
 492 }
 493
 494 static void __exit teql_exit(void)
 495 {
 496         struct teql_master *master, *nxt;
 497
 498         list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) {
 499
 500                 list_del(&master->master_list);
 501
 502                 unregister_qdisc(&master->qops);
 503                 unregister_netdev(master->dev);
 504                 free_netdev(master->dev);
 505         }
 506 }
 507
 508 module_init(teql_init);
 509 module_exit(teql_exit);
 510
 511 MODULE_LICENSE("GPL");