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 <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         struct net_device_stats stats;
  62 };
  63
  64 struct teql_sched_data
  65 {
  66         struct Qdisc *next;
  67         struct teql_master *m;
  68         struct neighbour *ncache;
  69         struct sk_buff_head q;
  70 };
  71
  72 #define NEXT_SLAVE(q) (((struct teql_sched_data*)qdisc_priv(q))->next)
  73
  74 #define FMASK (IFF_BROADCAST|IFF_POINTOPOINT)
  75
  76 /* "teql*" qdisc routines */
  77
  78 static int
  79 teql_enqueue(struct sk_buff *skb, struct Qdisc* sch)
  80 {
  81         struct net_device *dev = qdisc_dev(sch);
  82         struct teql_sched_data *q = qdisc_priv(sch);
  83
  84         if (q->q.qlen < dev->tx_queue_len) {
  85                 __skb_queue_tail(&q->q, skb);
  86                 sch->bstats.bytes += qdisc_pkt_len(skb);
  87                 sch->bstats.packets++;
  88                 return 0;
  89         }
  90
  91         kfree_skb(skb);
  92         sch->qstats.drops++;
  93         return NET_XMIT_DROP;
  94 }
  95
  96 static int
  97 teql_requeue(struct sk_buff *skb, struct Qdisc* sch)
  98 {
  99         struct teql_sched_data *q = qdisc_priv(sch);
 100
 101         __skb_queue_head(&q->q, skb);
 102         sch->qstats.requeues++;
 103         return 0;
 104 }
 105
 106 static struct sk_buff *
 107 teql_dequeue(struct Qdisc* sch)
 108 {
 109         struct teql_sched_data *dat = qdisc_priv(sch);
 110         struct netdev_queue *dat_queue;
 111         struct sk_buff *skb;
 112
 113         skb = __skb_dequeue(&dat->q);
 114         dat_queue = netdev_get_tx_queue(dat->m->dev, 0);
 115         if (skb == NULL) {
 116                 struct net_device *m = qdisc_dev(dat_queue->qdisc);
 117                 if (m) {
 118                         dat->m->slaves = sch;
 119                         netif_wake_queue(m);
 120                 }
 121         }
 122         sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen;
 123         return skb;
 124 }
 125
 126 static __inline__ void
 127 teql_neigh_release(struct neighbour *n)
 128 {
 129         if (n)
 130                 neigh_release(n);
 131 }
 132
 133 static void
 134 teql_reset(struct Qdisc* sch)
 135 {
 136         struct teql_sched_data *dat = qdisc_priv(sch);
 137
 138         skb_queue_purge(&dat->q);
 139         sch->q.qlen = 0;
 140         teql_neigh_release(xchg(&dat->ncache, NULL));
 141 }
 142
 143 static void
 144 teql_destroy(struct Qdisc* sch)
 145 {
 146         struct Qdisc *q, *prev;
 147         struct teql_sched_data *dat = qdisc_priv(sch);
 148         struct teql_master *master = dat->m;
 149
 150         if ((prev = master->slaves) != NULL) {
 151                 do {
 152                         q = NEXT_SLAVE(prev);
 153                         if (q == sch) {
 154                                 NEXT_SLAVE(prev) = NEXT_SLAVE(q);
 155                                 if (q == master->slaves) {
 156                                         master->slaves = NEXT_SLAVE(q);
 157                                         if (q == master->slaves) {
 158                                                 struct netdev_queue *txq;
 159                                                 spinlock_t *root_lock;
 160
 161                                                 txq = netdev_get_tx_queue(master->dev, 0);
 162                                                 master->slaves = NULL;
 163
 164                                                 root_lock = qdisc_root_lock(txq->qdisc);
 165                                                 spin_lock_bh(root_lock);
 166                                                 qdisc_reset(txq->qdisc);
 167                                                 spin_unlock_bh(root_lock);
 168                                         }
 169                                 }
 170                                 skb_queue_purge(&dat->q);
 171                                 teql_neigh_release(xchg(&dat->ncache, NULL));
 172                                 break;
 173                         }
 174
 175                 } while ((prev = q) != master->slaves);
 176         }
 177 }
 178
 179 static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt)
 180 {
 181         struct net_device *dev = qdisc_dev(sch);
 182         struct teql_master *m = (struct teql_master*)sch->ops;
 183         struct teql_sched_data *q = qdisc_priv(sch);
 184
 185         if (dev->hard_header_len > m->dev->hard_header_len)
 186                 return -EINVAL;
 187
 188         if (m->dev == dev)
 189                 return -ELOOP;
 190
 191         q->m = m;
 192
 193         skb_queue_head_init(&q->q);
 194
 195         if (m->slaves) {
 196                 if (m->dev->flags & IFF_UP) {
 197                         if ((m->dev->flags&IFF_POINTOPOINT && !(dev->flags&IFF_POINTOPOINT))
 198                             || (m->dev->flags&IFF_BROADCAST && !(dev->flags&IFF_BROADCAST))
 199                             || (m->dev->flags&IFF_MULTICAST && !(dev->flags&IFF_MULTICAST))
 200                             || dev->mtu < m->dev->mtu)
 201                                 return -EINVAL;
 202                 } else {
 203                         if (!(dev->flags&IFF_POINTOPOINT))
 204                                 m->dev->flags &= ~IFF_POINTOPOINT;
 205                         if (!(dev->flags&IFF_BROADCAST))
 206                                 m->dev->flags &= ~IFF_BROADCAST;
 207                         if (!(dev->flags&IFF_MULTICAST))
 208                                 m->dev->flags &= ~IFF_MULTICAST;
 209                         if (dev->mtu < m->dev->mtu)
 210                                 m->dev->mtu = dev->mtu;
 211                 }
 212                 q->next = NEXT_SLAVE(m->slaves);
 213                 NEXT_SLAVE(m->slaves) = sch;
 214         } else {
 215                 q->next = sch;
 216                 m->slaves = sch;
 217                 m->dev->mtu = dev->mtu;
 218                 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK);
 219         }
 220         return 0;
 221 }
 222
 223
 224 static int
 225 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
 226 {
 227         struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, 0);
 228         struct teql_sched_data *q = qdisc_priv(dev_queue->qdisc);
 229         struct neighbour *mn = skb->dst->neighbour;
 230         struct neighbour *n = q->ncache;
 231
 232         if (mn->tbl == NULL)
 233                 return -EINVAL;
 234         if (n && n->tbl == mn->tbl &&
 235             memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) {
 236                 atomic_inc(&n->refcnt);
 237         } else {
 238                 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev);
 239                 if (IS_ERR(n))
 240                         return PTR_ERR(n);
 241         }
 242         if (neigh_event_send(n, skb_res) == 0) {
 243                 int err;
 244
 245                 read_lock(&n->lock);
 246                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 247                                       n->ha, NULL, skb->len);
 248                 read_unlock(&n->lock);
 249
 250                 if (err < 0) {
 251                         neigh_release(n);
 252                         return -EINVAL;
 253                 }
 254                 teql_neigh_release(xchg(&q->ncache, n));
 255                 return 0;
 256         }
 257         neigh_release(n);
 258         return (skb_res == NULL) ? -EAGAIN : 1;
 259 }
 260
 261 static inline int teql_resolve(struct sk_buff *skb,
 262                                struct sk_buff *skb_res, struct net_device *dev)
 263 {
 264         struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
 265         if (txq->qdisc == &noop_qdisc)
 266                 return -ENODEV;
 267
 268         if (dev->header_ops == 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 subq = skb_get_queue_mapping(skb);
 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 = qdisc_dev(q);
 295                 struct netdev_queue *slave_txq;
 296
 297                 slave_txq = netdev_get_tx_queue(slave, 0);
 298                 if (slave_txq->qdisc_sleeping != q)
 299                         continue;
 300                 if (__netif_subqueue_stopped(slave, subq) ||
 301                     !netif_running(slave)) {
 302                         busy = 1;
 303                         continue;
 304                 }
 305
 306                 switch (teql_resolve(skb, skb_res, slave)) {
 307                 case 0:
 308                         if (netif_tx_trylock(slave)) {
 309                                 if (!__netif_subqueue_stopped(slave, subq) &&
 310                                     slave->hard_start_xmit(skb, slave) == 0) {
 311                                         netif_tx_unlock(slave);
 312                                         master->slaves = NEXT_SLAVE(q);
 313                                         netif_wake_queue(dev);
 314                                         master->stats.tx_packets++;
 315                                         master->stats.tx_bytes +=
 316                                                 qdisc_pkt_len(skb);
 317                                         return 0;
 318                                 }
 319                                 netif_tx_unlock(slave);
 320                         }
 321                         if (netif_queue_stopped(dev))
 322                                 busy = 1;
 323                         break;
 324                 case 1:
 325                         master->slaves = NEXT_SLAVE(q);
 326                         return 0;
 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 1;
 342         }
 343         master->stats.tx_errors++;
 344
 345 drop:
 346         master->stats.tx_dropped++;
 347         dev_kfree_skb(skb);
 348         return 0;
 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 struct net_device_stats *teql_master_stats(struct net_device *dev)
 400 {
 401         struct teql_master *m = netdev_priv(dev);
 402         return &m->stats;
 403 }
 404
 405 static int teql_master_mtu(struct net_device *dev, int new_mtu)
 406 {
 407         struct teql_master *m = netdev_priv(dev);
 408         struct Qdisc *q;
 409
 410         if (new_mtu < 68)
 411                 return -EINVAL;
 412
 413         q = m->slaves;
 414         if (q) {
 415                 do {
 416                         if (new_mtu > qdisc_dev(q)->mtu)
 417                                 return -EINVAL;
 418                 } while ((q=NEXT_SLAVE(q)) != m->slaves);
 419         }
 420
 421         dev->mtu = new_mtu;
 422         return 0;
 423 }
 424
 425 static __init void teql_master_setup(struct net_device *dev)
 426 {
 427         struct teql_master *master = netdev_priv(dev);
 428         struct Qdisc_ops *ops = &master->qops;
 429
 430         master->dev     = dev;
 431         ops->priv_size  = sizeof(struct teql_sched_data);
 432
 433         ops->enqueue    =       teql_enqueue;
 434         ops->dequeue    =       teql_dequeue;
 435         ops->requeue    =       teql_requeue;
 436         ops->init       =       teql_qdisc_init;
 437         ops->reset      =       teql_reset;
 438         ops->destroy    =       teql_destroy;
 439         ops->owner      =       THIS_MODULE;
 440
 441         dev->open               = teql_master_open;
 442         dev->hard_start_xmit    = teql_master_xmit;
 443         dev->stop               = teql_master_close;
 444         dev->get_stats          = teql_master_stats;
 445         dev->change_mtu         = teql_master_mtu;
 446         dev->type               = ARPHRD_VOID;
 447         dev->mtu                = 1500;
 448         dev->tx_queue_len       = 100;
 449         dev->flags              = IFF_NOARP;
 450         dev->hard_header_len    = LL_MAX_HEADER;
 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");