err.no Git - linux-2.6/blob - net/sched/sch_generic.c

   1 /*
   2  * net/sched/sch_generic.c      Generic packet scheduler routines.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *              Jamal Hadi Salim, <hadi@cyberus.ca> 990601
  11  *              - Ingress support
  12  */
  13
  14 #include <asm/uaccess.h>
  15 #include <asm/system.h>
  16 #include <linux/bitops.h>
  17 #include <linux/config.h>
  18 #include <linux/module.h>
  19 #include <linux/types.h>
  20 #include <linux/kernel.h>
  21 #include <linux/sched.h>
  22 #include <linux/string.h>
  23 #include <linux/mm.h>
  24 #include <linux/socket.h>
  25 #include <linux/sockios.h>
  26 #include <linux/in.h>
  27 #include <linux/errno.h>
  28 #include <linux/interrupt.h>
  29 #include <linux/netdevice.h>
  30 #include <linux/skbuff.h>
  31 #include <linux/rtnetlink.h>
  32 #include <linux/init.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/list.h>
  35 #include <net/sock.h>
  36 #include <net/pkt_sched.h>
  37
  38 /* Main transmission queue. */
  39
  40 /* Main qdisc structure lock.
  41
  42    However, modifications
  43    to data, participating in scheduling must be additionally
  44    protected with dev->queue_lock spinlock.
  45
  46    The idea is the following:
  47    - enqueue, dequeue are serialized via top level device
  48      spinlock dev->queue_lock.
  49    - tree walking is protected by read_lock_bh(qdisc_tree_lock)
  50      and this lock is used only in process context.
  51    - updates to tree are made under rtnl semaphore or
  52      from softirq context (__qdisc_destroy rcu-callback)
  53      hence this lock needs local bh disabling.
  54
  55    qdisc_tree_lock must be grabbed BEFORE dev->queue_lock!
  56  */
  57 DEFINE_RWLOCK(qdisc_tree_lock);
  58
  59 void qdisc_lock_tree(struct net_device *dev)
  60 {
  61         write_lock_bh(&qdisc_tree_lock);
  62         spin_lock_bh(&dev->queue_lock);
  63 }
  64
  65 void qdisc_unlock_tree(struct net_device *dev)
  66 {
  67         spin_unlock_bh(&dev->queue_lock);
  68         write_unlock_bh(&qdisc_tree_lock);
  69 }
  70
  71 /*
  72    dev->queue_lock serializes queue accesses for this device
  73    AND dev->qdisc pointer itself.
  74
  75    dev->xmit_lock serializes accesses to device driver.
  76
  77    dev->queue_lock and dev->xmit_lock are mutually exclusive,
  78    if one is grabbed, another must be free.
  79  */
  80
  81
  82 /* Kick device.
  83    Note, that this procedure can be called by a watchdog timer, so that
  84    we do not check dev->tbusy flag here.
  85
  86    Returns:  0  - queue is empty.
  87             >0  - queue is not empty, but throttled.
  88             <0  - queue is not empty. Device is throttled, if dev->tbusy != 0.
  89
  90    NOTE: Called under dev->queue_lock with locally disabled BH.
  91 */
  92
  93 int qdisc_restart(struct net_device *dev)
  94 {
  95         struct Qdisc *q = dev->qdisc;
  96         struct sk_buff *skb;
  97
  98         /* Dequeue packet */
  99         if ((skb = q->dequeue(q)) != NULL) {
 100                 unsigned nolock = (dev->features & NETIF_F_LLTX);
 101                 /*
 102                  * When the driver has LLTX set it does its own locking
 103                  * in start_xmit. No need to add additional overhead by
 104                  * locking again. These checks are worth it because
 105                  * even uncongested locks can be quite expensive.
 106                  * The driver can do trylock like here too, in case
 107                  * of lock congestion it should return -1 and the packet
 108                  * will be requeued.
 109                  */
 110                 if (!nolock) {
 111                         if (!spin_trylock(&dev->xmit_lock)) {
 112                         collision:
 113                                 /* So, someone grabbed the driver. */
 114
 115                                 /* It may be transient configuration error,
 116                                    when hard_start_xmit() recurses. We detect
 117                                    it by checking xmit owner and drop the
 118                                    packet when deadloop is detected.
 119                                 */
 120                                 if (dev->xmit_lock_owner == smp_processor_id()) {
 121                                         kfree_skb(skb);
 122                                         if (net_ratelimit())
 123                                                 printk(KERN_DEBUG "Dead loop on netdevice %s, fix it urgently!\n", dev->name);
 124                                         return -1;
 125                                 }
 126                                 __get_cpu_var(netdev_rx_stat).cpu_collision++;
 127                                 goto requeue;
 128                         }
 129                         /* Remember that the driver is grabbed by us. */
 130                         dev->xmit_lock_owner = smp_processor_id();
 131                 }
 132
 133                 {
 134                         /* And release queue */
 135                         spin_unlock(&dev->queue_lock);
 136
 137                         if (!netif_queue_stopped(dev)) {
 138                                 int ret;
 139                                 if (netdev_nit)
 140                                         dev_queue_xmit_nit(skb, dev);
 141
 142                                 ret = dev->hard_start_xmit(skb, dev);
 143                                 if (ret == NETDEV_TX_OK) {
 144                                         if (!nolock) {
 145                                                 dev->xmit_lock_owner = -1;
 146                                                 spin_unlock(&dev->xmit_lock);
 147                                         }
 148                                         spin_lock(&dev->queue_lock);
 149                                         return -1;
 150                                 }
 151                                 if (ret == NETDEV_TX_LOCKED && nolock) {
 152                                         spin_lock(&dev->queue_lock);
 153                                         goto collision;
 154                                 }
 155                         }
 156
 157                         /* NETDEV_TX_BUSY - we need to requeue */
 158                         /* Release the driver */
 159                         if (!nolock) {
 160                                 dev->xmit_lock_owner = -1;
 161                                 spin_unlock(&dev->xmit_lock);
 162                         }
 163                         spin_lock(&dev->queue_lock);
 164                         q = dev->qdisc;
 165                 }
 166
 167                 /* Device kicked us out :(
 168                    This is possible in three cases:
 169
 170                    0. driver is locked
 171                    1. fastroute is enabled
 172                    2. device cannot determine busy state
 173                       before start of transmission (f.e. dialout)
 174                    3. device is buggy (ppp)
 175                  */
 176
 177 requeue:
 178                 q->ops->requeue(skb, q);
 179                 netif_schedule(dev);
 180                 return 1;
 181         }
 182         BUG_ON((int) q->q.qlen < 0);
 183         return q->q.qlen;
 184 }
 185
 186 static void dev_watchdog(unsigned long arg)
 187 {
 188         struct net_device *dev = (struct net_device *)arg;
 189
 190         spin_lock(&dev->xmit_lock);
 191         if (dev->qdisc != &noop_qdisc) {
 192                 if (netif_device_present(dev) &&
 193                     netif_running(dev) &&
 194                     netif_carrier_ok(dev)) {
 195                         if (netif_queue_stopped(dev) &&
 196                             (jiffies - dev->trans_start) > dev->watchdog_timeo) {
 197                                 printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n", dev->name);
 198                                 dev->tx_timeout(dev);
 199                         }
 200                         if (!mod_timer(&dev->watchdog_timer, jiffies + dev->watchdog_timeo))
 201                                 dev_hold(dev);
 202                 }
 203         }
 204         spin_unlock(&dev->xmit_lock);
 205
 206         dev_put(dev);
 207 }
 208
 209 static void dev_watchdog_init(struct net_device *dev)
 210 {
 211         init_timer(&dev->watchdog_timer);
 212         dev->watchdog_timer.data = (unsigned long)dev;
 213         dev->watchdog_timer.function = dev_watchdog;
 214 }
 215
 216 void __netdev_watchdog_up(struct net_device *dev)
 217 {
 218         if (dev->tx_timeout) {
 219                 if (dev->watchdog_timeo <= 0)
 220                         dev->watchdog_timeo = 5*HZ;
 221                 if (!mod_timer(&dev->watchdog_timer, jiffies + dev->watchdog_timeo))
 222                         dev_hold(dev);
 223         }
 224 }
 225
 226 static void dev_watchdog_up(struct net_device *dev)
 227 {
 228         spin_lock_bh(&dev->xmit_lock);
 229         __netdev_watchdog_up(dev);
 230         spin_unlock_bh(&dev->xmit_lock);
 231 }
 232
 233 static void dev_watchdog_down(struct net_device *dev)
 234 {
 235         spin_lock_bh(&dev->xmit_lock);
 236         if (del_timer(&dev->watchdog_timer))
 237                 __dev_put(dev);
 238         spin_unlock_bh(&dev->xmit_lock);
 239 }
 240
 241 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 242    under all circumstances. It is difficult to invent anything faster or
 243    cheaper.
 244  */
 245
 246 static int
 247 noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
 248 {
 249         kfree_skb(skb);
 250         return NET_XMIT_CN;
 251 }
 252
 253 static struct sk_buff *
 254 noop_dequeue(struct Qdisc * qdisc)
 255 {
 256         return NULL;
 257 }
 258
 259 static int
 260 noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 261 {
 262         if (net_ratelimit())
 263                 printk(KERN_DEBUG "%s deferred output. It is buggy.\n", skb->dev->name);
 264         kfree_skb(skb);
 265         return NET_XMIT_CN;
 266 }
 267
 268 struct Qdisc_ops noop_qdisc_ops = {
 269         .next           =       NULL,
 270         .cl_ops         =       NULL,
 271         .id             =       "noop",
 272         .priv_size      =       0,
 273         .enqueue        =       noop_enqueue,
 274         .dequeue        =       noop_dequeue,
 275         .requeue        =       noop_requeue,
 276         .owner          =       THIS_MODULE,
 277 };
 278
 279 struct Qdisc noop_qdisc = {
 280         .enqueue        =       noop_enqueue,
 281         .dequeue        =       noop_dequeue,
 282         .flags          =       TCQ_F_BUILTIN,
 283         .ops            =       &noop_qdisc_ops,
 284         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
 285 };
 286
 287 static struct Qdisc_ops noqueue_qdisc_ops = {
 288         .next           =       NULL,
 289         .cl_ops         =       NULL,
 290         .id             =       "noqueue",
 291         .priv_size      =       0,
 292         .enqueue        =       noop_enqueue,
 293         .dequeue        =       noop_dequeue,
 294         .requeue        =       noop_requeue,
 295         .owner          =       THIS_MODULE,
 296 };
 297
 298 static struct Qdisc noqueue_qdisc = {
 299         .enqueue        =       NULL,
 300         .dequeue        =       noop_dequeue,
 301         .flags          =       TCQ_F_BUILTIN,
 302         .ops            =       &noqueue_qdisc_ops,
 303         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
 304 };
 305
 306
 307 static const u8 prio2band[TC_PRIO_MAX+1] =
 308         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
 309
 310 /* 3-band FIFO queue: old style, but should be a bit faster than
 311    generic prio+fifo combination.
 312  */
 313
 314 static int
 315 pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
 316 {
 317         struct sk_buff_head *list = qdisc_priv(qdisc);
 318
 319         list += prio2band[skb->priority&TC_PRIO_MAX];
 320
 321         if (skb_queue_len(list) < qdisc->dev->tx_queue_len) {
 322                 qdisc->q.qlen++;
 323                 return __qdisc_enqueue_tail(skb, qdisc, list);
 324         }
 325
 326         return qdisc_drop(skb, qdisc);
 327 }
 328
 329 static struct sk_buff *
 330 pfifo_fast_dequeue(struct Qdisc* qdisc)
 331 {
 332         int prio;
 333         struct sk_buff_head *list = qdisc_priv(qdisc);
 334
 335         for (prio = 0; prio < 3; prio++, list++) {
 336                 struct sk_buff *skb = __qdisc_dequeue_head(qdisc, list);
 337                 if (skb) {
 338                         qdisc->q.qlen--;
 339                         return skb;
 340                 }
 341         }
 342         return NULL;
 343 }
 344
 345 static int
 346 pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 347 {
 348         struct sk_buff_head *list = qdisc_priv(qdisc);
 349
 350         list += prio2band[skb->priority&TC_PRIO_MAX];
 351
 352         qdisc->q.qlen++;
 353         return __qdisc_requeue(skb, qdisc, list);
 354 }
 355
 356 static void
 357 pfifo_fast_reset(struct Qdisc* qdisc)
 358 {
 359         int prio;
 360         struct sk_buff_head *list = qdisc_priv(qdisc);
 361
 362         for (prio=0; prio < 3; prio++)
 363                 __qdisc_reset_queue(qdisc, list + prio);
 364
 365         qdisc->qstats.backlog = 0;
 366         qdisc->q.qlen = 0;
 367 }
 368
 369 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 370 {
 371         unsigned char    *b = skb->tail;
 372         struct tc_prio_qopt opt;
 373
 374         opt.bands = 3;
 375         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
 376         RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 377         return skb->len;
 378
 379 rtattr_failure:
 380         skb_trim(skb, b - skb->data);
 381         return -1;
 382 }
 383
 384 static int pfifo_fast_init(struct Qdisc *qdisc, struct rtattr *opt)
 385 {
 386         int i;
 387         struct sk_buff_head *list = qdisc_priv(qdisc);
 388
 389         for (i=0; i<3; i++)
 390                 skb_queue_head_init(list+i);
 391
 392         return 0;
 393 }
 394
 395 static struct Qdisc_ops pfifo_fast_ops = {
 396         .next           =       NULL,
 397         .cl_ops         =       NULL,
 398         .id             =       "pfifo_fast",
 399         .priv_size      =       3 * sizeof(struct sk_buff_head),
 400         .enqueue        =       pfifo_fast_enqueue,
 401         .dequeue        =       pfifo_fast_dequeue,
 402         .requeue        =       pfifo_fast_requeue,
 403         .init           =       pfifo_fast_init,
 404         .reset          =       pfifo_fast_reset,
 405         .dump           =       pfifo_fast_dump,
 406         .owner          =       THIS_MODULE,
 407 };
 408
 409 struct Qdisc * qdisc_create_dflt(struct net_device *dev, struct Qdisc_ops *ops)
 410 {
 411         void *p;
 412         struct Qdisc *sch;
 413         int size;
 414
 415         /* ensure that the Qdisc and the private data are 32-byte aligned */
 416         size = ((sizeof(*sch) + QDISC_ALIGN_CONST) & ~QDISC_ALIGN_CONST);
 417         size += ops->priv_size + QDISC_ALIGN_CONST;
 418
 419         p = kmalloc(size, GFP_KERNEL);
 420         if (!p)
 421                 return NULL;
 422         memset(p, 0, size);
 423
 424         sch = (struct Qdisc *)(((unsigned long)p + QDISC_ALIGN_CONST)
 425                                & ~QDISC_ALIGN_CONST);
 426         sch->padded = (char *)sch - (char *)p;
 427
 428         INIT_LIST_HEAD(&sch->list);
 429         skb_queue_head_init(&sch->q);
 430         sch->ops = ops;
 431         sch->enqueue = ops->enqueue;
 432         sch->dequeue = ops->dequeue;
 433         sch->dev = dev;
 434         dev_hold(dev);
 435         sch->stats_lock = &dev->queue_lock;
 436         atomic_set(&sch->refcnt, 1);
 437         if (!ops->init || ops->init(sch, NULL) == 0)
 438                 return sch;
 439
 440         dev_put(dev);
 441         kfree(p);
 442         return NULL;
 443 }
 444
 445 /* Under dev->queue_lock and BH! */
 446
 447 void qdisc_reset(struct Qdisc *qdisc)
 448 {
 449         struct Qdisc_ops *ops = qdisc->ops;
 450
 451         if (ops->reset)
 452                 ops->reset(qdisc);
 453 }
 454
 455 /* this is the rcu callback function to clean up a qdisc when there
 456  * are no further references to it */
 457
 458 static void __qdisc_destroy(struct rcu_head *head)
 459 {
 460         struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu);
 461         struct Qdisc_ops  *ops = qdisc->ops;
 462
 463 #ifdef CONFIG_NET_ESTIMATOR
 464         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
 465 #endif
 466         write_lock(&qdisc_tree_lock);
 467         if (ops->reset)
 468                 ops->reset(qdisc);
 469         if (ops->destroy)
 470                 ops->destroy(qdisc);
 471         write_unlock(&qdisc_tree_lock);
 472         module_put(ops->owner);
 473
 474         dev_put(qdisc->dev);
 475         kfree((char *) qdisc - qdisc->padded);
 476 }
 477
 478 /* Under dev->queue_lock and BH! */
 479
 480 void qdisc_destroy(struct Qdisc *qdisc)
 481 {
 482         struct list_head cql = LIST_HEAD_INIT(cql);
 483         struct Qdisc *cq, *q, *n;
 484
 485         if (qdisc->flags & TCQ_F_BUILTIN ||
 486                 !atomic_dec_and_test(&qdisc->refcnt))
 487                 return;
 488
 489         if (!list_empty(&qdisc->list)) {
 490                 if (qdisc->ops->cl_ops == NULL)
 491                         list_del(&qdisc->list);
 492                 else
 493                         list_move(&qdisc->list, &cql);
 494         }
 495
 496         /* unlink inner qdiscs from dev->qdisc_list immediately */
 497         list_for_each_entry(cq, &cql, list)
 498                 list_for_each_entry_safe(q, n, &qdisc->dev->qdisc_list, list)
 499                         if (TC_H_MAJ(q->parent) == TC_H_MAJ(cq->handle)) {
 500                                 if (q->ops->cl_ops == NULL)
 501                                         list_del_init(&q->list);
 502                                 else
 503                                         list_move_tail(&q->list, &cql);
 504                         }
 505         list_for_each_entry_safe(cq, n, &cql, list)
 506                 list_del_init(&cq->list);
 507
 508         call_rcu(&qdisc->q_rcu, __qdisc_destroy);
 509 }
 510
 511 void dev_activate(struct net_device *dev)
 512 {
 513         /* No queueing discipline is attached to device;
 514            create default one i.e. pfifo_fast for devices,
 515            which need queueing and noqueue_qdisc for
 516            virtual interfaces
 517          */
 518
 519         if (dev->qdisc_sleeping == &noop_qdisc) {
 520                 struct Qdisc *qdisc;
 521                 if (dev->tx_queue_len) {
 522                         qdisc = qdisc_create_dflt(dev, &pfifo_fast_ops);
 523                         if (qdisc == NULL) {
 524                                 printk(KERN_INFO "%s: activation failed\n", dev->name);
 525                                 return;
 526                         }
 527                         write_lock_bh(&qdisc_tree_lock);
 528                         list_add_tail(&qdisc->list, &dev->qdisc_list);
 529                         write_unlock_bh(&qdisc_tree_lock);
 530                 } else {
 531                         qdisc =  &noqueue_qdisc;
 532                 }
 533                 write_lock_bh(&qdisc_tree_lock);
 534                 dev->qdisc_sleeping = qdisc;
 535                 write_unlock_bh(&qdisc_tree_lock);
 536         }
 537
 538         if (!netif_carrier_ok(dev))
 539                 /* Delay activation until next carrier-on event */
 540                 return;
 541
 542         spin_lock_bh(&dev->queue_lock);
 543         rcu_assign_pointer(dev->qdisc, dev->qdisc_sleeping);
 544         if (dev->qdisc != &noqueue_qdisc) {
 545                 dev->trans_start = jiffies;
 546                 dev_watchdog_up(dev);
 547         }
 548         spin_unlock_bh(&dev->queue_lock);
 549 }
 550
 551 void dev_deactivate(struct net_device *dev)
 552 {
 553         struct Qdisc *qdisc;
 554
 555         spin_lock_bh(&dev->queue_lock);
 556         qdisc = dev->qdisc;
 557         dev->qdisc = &noop_qdisc;
 558
 559         qdisc_reset(qdisc);
 560
 561         spin_unlock_bh(&dev->queue_lock);
 562
 563         dev_watchdog_down(dev);
 564
 565         while (test_bit(__LINK_STATE_SCHED, &dev->state))
 566                 yield();
 567
 568         spin_unlock_wait(&dev->xmit_lock);
 569 }
 570
 571 void dev_init_scheduler(struct net_device *dev)
 572 {
 573         qdisc_lock_tree(dev);
 574         dev->qdisc = &noop_qdisc;
 575         dev->qdisc_sleeping = &noop_qdisc;
 576         INIT_LIST_HEAD(&dev->qdisc_list);
 577         qdisc_unlock_tree(dev);
 578
 579         dev_watchdog_init(dev);
 580 }
 581
 582 void dev_shutdown(struct net_device *dev)
 583 {
 584         struct Qdisc *qdisc;
 585
 586         qdisc_lock_tree(dev);
 587         qdisc = dev->qdisc_sleeping;
 588         dev->qdisc = &noop_qdisc;
 589         dev->qdisc_sleeping = &noop_qdisc;
 590         qdisc_destroy(qdisc);
 591 #if defined(CONFIG_NET_SCH_INGRESS) || defined(CONFIG_NET_SCH_INGRESS_MODULE)
 592         if ((qdisc = dev->qdisc_ingress) != NULL) {
 593                 dev->qdisc_ingress = NULL;
 594                 qdisc_destroy(qdisc);
 595         }
 596 #endif
 597         BUG_TRAP(!timer_pending(&dev->watchdog_timer));
 598         qdisc_unlock_tree(dev);
 599 }
 600
 601 EXPORT_SYMBOL(__netdev_watchdog_up);
 602 EXPORT_SYMBOL(noop_qdisc);
 603 EXPORT_SYMBOL(noop_qdisc_ops);
 604 EXPORT_SYMBOL(qdisc_create_dflt);
 605 EXPORT_SYMBOL(qdisc_destroy);
 606 EXPORT_SYMBOL(qdisc_reset);
 607 EXPORT_SYMBOL(qdisc_restart);
 608 EXPORT_SYMBOL(qdisc_lock_tree);
 609 EXPORT_SYMBOL(qdisc_unlock_tree);