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/slab.h>
  15 #include <linux/string.h>
  16 #include <linux/errno.h>
  17 #include <linux/if_arp.h>
  18 #include <linux/netdevice.h>
  19 #include <linux/init.h>
  20 #include <linux/skbuff.h>
  21 #include <linux/moduleparam.h>
  22 #include <net/dst.h>
  23 #include <net/neighbour.h>
  24 #include <net/pkt_sched.h>
  25
  26 /*
  27    How to setup it.
  28    ----------------
  29
  30    After loading this module you will find a new device teqlN
  31    and new qdisc with the same name. To join a slave to the equalizer
  32    you should just set this qdisc on a device f.e.
  33
  34    # tc qdisc add dev eth0 root teql0
  35    # tc qdisc add dev eth1 root teql0
  36
  37    That's all. Full PnP 8)
  38
  39    Applicability.
  40    --------------
  41
  42    1. Slave devices MUST be active devices, i.e., they must raise the tbusy
  43       signal and generate EOI events. If you want to equalize virtual devices
  44       like tunnels, use a normal eql device.
  45    2. This device puts no limitations on physical slave characteristics
  46       f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-)
  47       Certainly, large difference in link speeds will make the resulting
  48       eqalized link unusable, because of huge packet reordering.
  49       I estimate an upper useful difference as ~10 times.
  50    3. If the slave requires address resolution, only protocols using
  51       neighbour cache (IPv4/IPv6) will work over the equalized link.
  52       Other protocols are still allowed to use the slave device directly,
  53       which will not break load balancing, though native slave
  54       traffic will have the highest priority.  */
  55
  56 struct teql_master
  57 {
  58         struct Qdisc_ops qops;
  59         struct net_device *dev;
  60         struct Qdisc *slaves;
  61         struct list_head master_list;
  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 struct sk_buff *
  97 teql_dequeue(struct Qdisc* sch)
  98 {
  99         struct teql_sched_data *dat = qdisc_priv(sch);
 100         struct netdev_queue *dat_queue;
 101         struct sk_buff *skb;
 102
 103         skb = __skb_dequeue(&dat->q);
 104         dat_queue = netdev_get_tx_queue(dat->m->dev, 0);
 105         if (skb == NULL) {
 106                 struct net_device *m = qdisc_dev(dat_queue->qdisc);
 107                 if (m) {
 108                         dat->m->slaves = sch;
 109                         netif_wake_queue(m);
 110                 }
 111         }
 112         sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen;
 113         return skb;
 114 }
 115
 116 static struct sk_buff *
 117 teql_peek(struct Qdisc* sch)
 118 {
 119         /* teql is meant to be used as root qdisc */
 120         return NULL;
 121 }
 122
 123 static __inline__ void
 124 teql_neigh_release(struct neighbour *n)
 125 {
 126         if (n)
 127                 neigh_release(n);
 128 }
 129
 130 static void
 131 teql_reset(struct Qdisc* sch)
 132 {
 133         struct teql_sched_data *dat = qdisc_priv(sch);
 134
 135         skb_queue_purge(&dat->q);
 136         sch->q.qlen = 0;
 137         teql_neigh_release(xchg(&dat->ncache, NULL));
 138 }
 139
 140 static void
 141 teql_destroy(struct Qdisc* sch)
 142 {
 143         struct Qdisc *q, *prev;
 144         struct teql_sched_data *dat = qdisc_priv(sch);
 145         struct teql_master *master = dat->m;
 146
 147         if ((prev = master->slaves) != NULL) {
 148                 do {
 149                         q = NEXT_SLAVE(prev);
 150                         if (q == sch) {
 151                                 NEXT_SLAVE(prev) = NEXT_SLAVE(q);
 152                                 if (q == master->slaves) {
 153                                         master->slaves = NEXT_SLAVE(q);
 154                                         if (q == master->slaves) {
 155                                                 struct netdev_queue *txq;
 156                                                 spinlock_t *root_lock;
 157
 158                                                 txq = netdev_get_tx_queue(master->dev, 0);
 159                                                 master->slaves = NULL;
 160
 161                                                 root_lock = qdisc_root_sleeping_lock(txq->qdisc);
 162                                                 spin_lock_bh(root_lock);
 163                                                 qdisc_reset(txq->qdisc);
 164                                                 spin_unlock_bh(root_lock);
 165                                         }
 166                                 }
 167                                 skb_queue_purge(&dat->q);
 168                                 teql_neigh_release(xchg(&dat->ncache, NULL));
 169                                 break;
 170                         }
 171
 172                 } while ((prev = q) != master->slaves);
 173         }
 174 }
 175
 176 static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt)
 177 {
 178         struct net_device *dev = qdisc_dev(sch);
 179         struct teql_master *m = (struct teql_master*)sch->ops;
 180         struct teql_sched_data *q = qdisc_priv(sch);
 181
 182         if (dev->hard_header_len > m->dev->hard_header_len)
 183                 return -EINVAL;
 184
 185         if (m->dev == dev)
 186                 return -ELOOP;
 187
 188         q->m = m;
 189
 190         skb_queue_head_init(&q->q);
 191
 192         if (m->slaves) {
 193                 if (m->dev->flags & IFF_UP) {
 194                         if ((m->dev->flags & IFF_POINTOPOINT &&
 195                              !(dev->flags & IFF_POINTOPOINT)) ||
 196                             (m->dev->flags & IFF_BROADCAST &&
 197                              !(dev->flags & IFF_BROADCAST)) ||
 198                             (m->dev->flags & IFF_MULTICAST &&
 199                              !(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(skb)->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(skb) == NULL ||
 270             skb_dst(skb)->neighbour == NULL)
 271                 return 0;
 272         return __teql_resolve(skb, skb_res, dev);
 273 }
 274
 275 static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
 276 {
 277         struct teql_master *master = netdev_priv(dev);
 278         struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
 279         struct Qdisc *start, *q;
 280         int busy;
 281         int nores;
 282         int subq = skb_get_queue_mapping(skb);
 283         struct sk_buff *skb_res = NULL;
 284
 285         start = master->slaves;
 286
 287 restart:
 288         nores = 0;
 289         busy = 0;
 290
 291         if ((q = start) == NULL)
 292                 goto drop;
 293
 294         do {
 295                 struct net_device *slave = qdisc_dev(q);
 296                 struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0);
 297                 const struct net_device_ops *slave_ops = slave->netdev_ops;
 298
 299                 if (slave_txq->qdisc_sleeping != q)
 300                         continue;
 301                 if (__netif_subqueue_stopped(slave, subq) ||
 302                     !netif_running(slave)) {
 303                         busy = 1;
 304                         continue;
 305                 }
 306
 307                 switch (teql_resolve(skb, skb_res, slave)) {
 308                 case 0:
 309                         if (__netif_tx_trylock(slave_txq)) {
 310                                 unsigned int length = qdisc_pkt_len(skb);
 311
 312                                 if (!netif_tx_queue_stopped(slave_txq) &&
 313                                     !netif_tx_queue_frozen(slave_txq) &&
 314                                     slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) {
 315                                         txq_trans_update(slave_txq);
 316                                         __netif_tx_unlock(slave_txq);
 317                                         master->slaves = NEXT_SLAVE(q);
 318                                         netif_wake_queue(dev);
 319                                         txq->tx_packets++;
 320                                         txq->tx_bytes += length;
 321                                         return NETDEV_TX_OK;
 322                                 }
 323                                 __netif_tx_unlock(slave_txq);
 324                         }
 325                         if (netif_queue_stopped(dev))
 326                                 busy = 1;
 327                         break;
 328                 case 1:
 329                         master->slaves = NEXT_SLAVE(q);
 330                         return NETDEV_TX_OK;
 331                 default:
 332                         nores = 1;
 333                         break;
 334                 }
 335                 __skb_pull(skb, skb_network_offset(skb));
 336         } while ((q = NEXT_SLAVE(q)) != start);
 337
 338         if (nores && skb_res == NULL) {
 339                 skb_res = skb;
 340                 goto restart;
 341         }
 342
 343         if (busy) {
 344                 netif_stop_queue(dev);
 345                 return NETDEV_TX_BUSY;
 346         }
 347         dev->stats.tx_errors++;
 348
 349 drop:
 350         txq->tx_dropped++;
 351         dev_kfree_skb(skb);
 352         return NETDEV_TX_OK;
 353 }
 354
 355 static int teql_master_open(struct net_device *dev)
 356 {
 357         struct Qdisc * q;
 358         struct teql_master *m = netdev_priv(dev);
 359         int mtu = 0xFFFE;
 360         unsigned flags = IFF_NOARP|IFF_MULTICAST;
 361
 362         if (m->slaves == NULL)
 363                 return -EUNATCH;
 364
 365         flags = FMASK;
 366
 367         q = m->slaves;
 368         do {
 369                 struct net_device *slave = qdisc_dev(q);
 370
 371                 if (slave == NULL)
 372                         return -EUNATCH;
 373
 374                 if (slave->mtu < mtu)
 375                         mtu = slave->mtu;
 376                 if (slave->hard_header_len > LL_MAX_HEADER)
 377                         return -EINVAL;
 378
 379                 /* If all the slaves are BROADCAST, master is BROADCAST
 380                    If all the slaves are PtP, master is PtP
 381                    Otherwise, master is NBMA.
 382                  */
 383                 if (!(slave->flags&IFF_POINTOPOINT))
 384                         flags &= ~IFF_POINTOPOINT;
 385                 if (!(slave->flags&IFF_BROADCAST))
 386                         flags &= ~IFF_BROADCAST;
 387                 if (!(slave->flags&IFF_MULTICAST))
 388                         flags &= ~IFF_MULTICAST;
 389         } while ((q = NEXT_SLAVE(q)) != m->slaves);
 390
 391         m->dev->mtu = mtu;
 392         m->dev->flags = (m->dev->flags&~FMASK) | flags;
 393         netif_start_queue(m->dev);
 394         return 0;
 395 }
 396
 397 static int teql_master_close(struct net_device *dev)
 398 {
 399         netif_stop_queue(dev);
 400         return 0;
 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 > qdisc_dev(q)->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 const struct net_device_ops teql_netdev_ops = {
 424         .ndo_open       = teql_master_open,
 425         .ndo_stop       = teql_master_close,
 426         .ndo_start_xmit = teql_master_xmit,
 427         .ndo_change_mtu = teql_master_mtu,
 428 };
 429
 430 static __init void teql_master_setup(struct net_device *dev)
 431 {
 432         struct teql_master *master = netdev_priv(dev);
 433         struct Qdisc_ops *ops = &master->qops;
 434
 435         master->dev     = dev;
 436         ops->priv_size  = sizeof(struct teql_sched_data);
 437
 438         ops->enqueue    =       teql_enqueue;
 439         ops->dequeue    =       teql_dequeue;
 440         ops->peek       =       teql_peek;
 441         ops->init       =       teql_qdisc_init;
 442         ops->reset      =       teql_reset;
 443         ops->destroy    =       teql_destroy;
 444         ops->owner      =       THIS_MODULE;
 445
 446         dev->netdev_ops =       &teql_netdev_ops;
 447         dev->type               = ARPHRD_VOID;
 448         dev->mtu                = 1500;
 449         dev->tx_queue_len       = 100;
 450         dev->flags              = IFF_NOARP;
 451         dev->hard_header_len    = LL_MAX_HEADER;
 452 }
 453
 454 static LIST_HEAD(master_dev_list);
 455 static int max_equalizers = 1;
 456 module_param(max_equalizers, int, 0);
 457 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers");
 458
 459 static int __init teql_init(void)
 460 {
 461         int i;
 462         int err = -ENODEV;
 463
 464         for (i = 0; i < max_equalizers; i++) {
 465                 struct net_device *dev;
 466                 struct teql_master *master;
 467
 468                 dev = alloc_netdev(sizeof(struct teql_master),
 469                                   "teql%d", teql_master_setup);
 470                 if (!dev) {
 471                         err = -ENOMEM;
 472                         break;
 473                 }
 474
 475                 if ((err = register_netdev(dev))) {
 476                         free_netdev(dev);
 477                         break;
 478                 }
 479
 480                 master = netdev_priv(dev);
 481
 482                 strlcpy(master->qops.id, dev->name, IFNAMSIZ);
 483                 err = register_qdisc(&master->qops);
 484
 485                 if (err) {
 486                         unregister_netdev(dev);
 487                         free_netdev(dev);
 488                         break;
 489                 }
 490
 491                 list_add_tail(&master->master_list, &master_dev_list);
 492         }
 493         return i ? 0 : err;
 494 }
 495
 496 static void __exit teql_exit(void)
 497 {
 498         struct teql_master *master, *nxt;
 499
 500         list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) {
 501
 502                 list_del(&master->master_list);
 503
 504                 unregister_qdisc(&master->qops);
 505                 unregister_netdev(master->dev);
 506                 free_netdev(master->dev);
 507         }
 508 }
 509
 510 module_init(teql_init);
 511 module_exit(teql_exit);
 512
 513 MODULE_LICENSE("GPL");