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   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 <linux/bitops.h>
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/sched.h>
  19 #include <linux/string.h>
  20 #include <linux/errno.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/rtnetlink.h>
  24 #include <linux/init.h>
  25 #include <linux/rcupdate.h>
  26 #include <linux/list.h>
  27 #include <net/pkt_sched.h>
  28
  29 /* Main transmission queue. */
  30
  31 /* Modifications to data participating in scheduling must be protected with
  32  * queue->lock spinlock.
  33  *
  34  * The idea is the following:
  35  * - enqueue, dequeue are serialized via top level device
  36  *   spinlock queue->lock.
  37  * - ingress filtering is serialized via top level device
  38  *   spinlock dev->rx_queue.lock.
  39  * - updates to tree and tree walking are only done under the rtnl mutex.
  40  */
  41
  42 void qdisc_lock_tree(struct net_device *dev)
  43         __acquires(dev->tx_queue.lock)
  44         __acquires(dev->rx_queue.lock)
  45 {
  46         spin_lock_bh(&dev->tx_queue.lock);
  47         spin_lock(&dev->rx_queue.lock);
  48 }
  49 EXPORT_SYMBOL(qdisc_lock_tree);
  50
  51 void qdisc_unlock_tree(struct net_device *dev)
  52         __releases(dev->rx_queue.lock)
  53         __releases(dev->tx_queue.lock)
  54 {
  55         spin_unlock(&dev->rx_queue.lock);
  56         spin_unlock_bh(&dev->tx_queue.lock);
  57 }
  58 EXPORT_SYMBOL(qdisc_unlock_tree);
  59
  60 static inline int qdisc_qlen(struct Qdisc *q)
  61 {
  62         return q->q.qlen;
  63 }
  64
  65 static inline int dev_requeue_skb(struct sk_buff *skb, struct net_device *dev,
  66                                   struct Qdisc *q)
  67 {
  68         if (unlikely(skb->next))
  69                 dev->gso_skb = skb;
  70         else
  71                 q->ops->requeue(skb, q);
  72
  73         netif_schedule(dev);
  74         return 0;
  75 }
  76
  77 static inline struct sk_buff *dev_dequeue_skb(struct net_device *dev,
  78                                               struct Qdisc *q)
  79 {
  80         struct sk_buff *skb;
  81
  82         if ((skb = dev->gso_skb))
  83                 dev->gso_skb = NULL;
  84         else
  85                 skb = q->dequeue(q);
  86
  87         return skb;
  88 }
  89
  90 static inline int handle_dev_cpu_collision(struct sk_buff *skb,
  91                                            struct net_device *dev,
  92                                            struct Qdisc *q)
  93 {
  94         int ret;
  95
  96         if (unlikely(dev->xmit_lock_owner == smp_processor_id())) {
  97                 /*
  98                  * Same CPU holding the lock. It may be a transient
  99                  * configuration error, when hard_start_xmit() recurses. We
 100                  * detect it by checking xmit owner and drop the packet when
 101                  * deadloop is detected. Return OK to try the next skb.
 102                  */
 103                 kfree_skb(skb);
 104                 if (net_ratelimit())
 105                         printk(KERN_WARNING "Dead loop on netdevice %s, "
 106                                "fix it urgently!\n", dev->name);
 107                 ret = qdisc_qlen(q);
 108         } else {
 109                 /*
 110                  * Another cpu is holding lock, requeue & delay xmits for
 111                  * some time.
 112                  */
 113                 __get_cpu_var(netdev_rx_stat).cpu_collision++;
 114                 ret = dev_requeue_skb(skb, dev, q);
 115         }
 116
 117         return ret;
 118 }
 119
 120 /*
 121  * NOTE: Called under queue->lock with locally disabled BH.
 122  *
 123  * __LINK_STATE_QDISC_RUNNING guarantees only one CPU can process this
 124  * device at a time. queue->lock serializes queue accesses for
 125  * this device AND txq->qdisc pointer itself.
 126  *
 127  *  netif_tx_lock serializes accesses to device driver.
 128  *
 129  *  queue->lock and netif_tx_lock are mutually exclusive,
 130  *  if one is grabbed, another must be free.
 131  *
 132  * Note, that this procedure can be called by a watchdog timer
 133  *
 134  * Returns to the caller:
 135  *                              0  - queue is empty or throttled.
 136  *                              >0 - queue is not empty.
 137  *
 138  */
 139 static inline int qdisc_restart(struct net_device *dev)
 140 {
 141         struct netdev_queue *txq = &dev->tx_queue;
 142         struct Qdisc *q = txq->qdisc;
 143         struct sk_buff *skb;
 144         int ret = NETDEV_TX_BUSY;
 145
 146         /* Dequeue packet */
 147         if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL))
 148                 return 0;
 149
 150
 151         /* And release queue */
 152         spin_unlock(&txq->lock);
 153
 154         HARD_TX_LOCK(dev, smp_processor_id());
 155         if (!netif_subqueue_stopped(dev, skb))
 156                 ret = dev_hard_start_xmit(skb, dev);
 157         HARD_TX_UNLOCK(dev);
 158
 159         spin_lock(&txq->lock);
 160         q = txq->qdisc;
 161
 162         switch (ret) {
 163         case NETDEV_TX_OK:
 164                 /* Driver sent out skb successfully */
 165                 ret = qdisc_qlen(q);
 166                 break;
 167
 168         case NETDEV_TX_LOCKED:
 169                 /* Driver try lock failed */
 170                 ret = handle_dev_cpu_collision(skb, dev, q);
 171                 break;
 172
 173         default:
 174                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 175                 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
 176                         printk(KERN_WARNING "BUG %s code %d qlen %d\n",
 177                                dev->name, ret, q->q.qlen);
 178
 179                 ret = dev_requeue_skb(skb, dev, q);
 180                 break;
 181         }
 182
 183         return ret;
 184 }
 185
 186 void __qdisc_run(struct net_device *dev)
 187 {
 188         unsigned long start_time = jiffies;
 189
 190         while (qdisc_restart(dev)) {
 191                 if (netif_queue_stopped(dev))
 192                         break;
 193
 194                 /*
 195                  * Postpone processing if
 196                  * 1. another process needs the CPU;
 197                  * 2. we've been doing it for too long.
 198                  */
 199                 if (need_resched() || jiffies != start_time) {
 200                         netif_schedule(dev);
 201                         break;
 202                 }
 203         }
 204
 205         clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
 206 }
 207
 208 static void dev_watchdog(unsigned long arg)
 209 {
 210         struct net_device *dev = (struct net_device *)arg;
 211         struct netdev_queue *txq = &dev->tx_queue;
 212
 213         netif_tx_lock(dev);
 214         if (txq->qdisc != &noop_qdisc) {
 215                 if (netif_device_present(dev) &&
 216                     netif_running(dev) &&
 217                     netif_carrier_ok(dev)) {
 218                         if (netif_queue_stopped(dev) &&
 219                             time_after(jiffies, dev->trans_start + dev->watchdog_timeo)) {
 220
 221                                 printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n",
 222                                        dev->name);
 223                                 dev->tx_timeout(dev);
 224                                 WARN_ON_ONCE(1);
 225                         }
 226                         if (!mod_timer(&dev->watchdog_timer, round_jiffies(jiffies + dev->watchdog_timeo)))
 227                                 dev_hold(dev);
 228                 }
 229         }
 230         netif_tx_unlock(dev);
 231
 232         dev_put(dev);
 233 }
 234
 235 void __netdev_watchdog_up(struct net_device *dev)
 236 {
 237         if (dev->tx_timeout) {
 238                 if (dev->watchdog_timeo <= 0)
 239                         dev->watchdog_timeo = 5*HZ;
 240                 if (!mod_timer(&dev->watchdog_timer,
 241                                round_jiffies(jiffies + dev->watchdog_timeo)))
 242                         dev_hold(dev);
 243         }
 244 }
 245
 246 static void dev_watchdog_up(struct net_device *dev)
 247 {
 248         __netdev_watchdog_up(dev);
 249 }
 250
 251 static void dev_watchdog_down(struct net_device *dev)
 252 {
 253         netif_tx_lock_bh(dev);
 254         if (del_timer(&dev->watchdog_timer))
 255                 dev_put(dev);
 256         netif_tx_unlock_bh(dev);
 257 }
 258
 259 /**
 260  *      netif_carrier_on - set carrier
 261  *      @dev: network device
 262  *
 263  * Device has detected that carrier.
 264  */
 265 void netif_carrier_on(struct net_device *dev)
 266 {
 267         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 268                 linkwatch_fire_event(dev);
 269                 if (netif_running(dev))
 270                         __netdev_watchdog_up(dev);
 271         }
 272 }
 273 EXPORT_SYMBOL(netif_carrier_on);
 274
 275 /**
 276  *      netif_carrier_off - clear carrier
 277  *      @dev: network device
 278  *
 279  * Device has detected loss of carrier.
 280  */
 281 void netif_carrier_off(struct net_device *dev)
 282 {
 283         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state))
 284                 linkwatch_fire_event(dev);
 285 }
 286 EXPORT_SYMBOL(netif_carrier_off);
 287
 288 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 289    under all circumstances. It is difficult to invent anything faster or
 290    cheaper.
 291  */
 292
 293 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
 294 {
 295         kfree_skb(skb);
 296         return NET_XMIT_CN;
 297 }
 298
 299 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
 300 {
 301         return NULL;
 302 }
 303
 304 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 305 {
 306         if (net_ratelimit())
 307                 printk(KERN_DEBUG "%s deferred output. It is buggy.\n",
 308                        skb->dev->name);
 309         kfree_skb(skb);
 310         return NET_XMIT_CN;
 311 }
 312
 313 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 314         .id             =       "noop",
 315         .priv_size      =       0,
 316         .enqueue        =       noop_enqueue,
 317         .dequeue        =       noop_dequeue,
 318         .requeue        =       noop_requeue,
 319         .owner          =       THIS_MODULE,
 320 };
 321
 322 struct Qdisc noop_qdisc = {
 323         .enqueue        =       noop_enqueue,
 324         .dequeue        =       noop_dequeue,
 325         .flags          =       TCQ_F_BUILTIN,
 326         .ops            =       &noop_qdisc_ops,
 327         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
 328 };
 329 EXPORT_SYMBOL(noop_qdisc);
 330
 331 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 332         .id             =       "noqueue",
 333         .priv_size      =       0,
 334         .enqueue        =       noop_enqueue,
 335         .dequeue        =       noop_dequeue,
 336         .requeue        =       noop_requeue,
 337         .owner          =       THIS_MODULE,
 338 };
 339
 340 static struct Qdisc noqueue_qdisc = {
 341         .enqueue        =       NULL,
 342         .dequeue        =       noop_dequeue,
 343         .flags          =       TCQ_F_BUILTIN,
 344         .ops            =       &noqueue_qdisc_ops,
 345         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
 346 };
 347
 348
 349 static const u8 prio2band[TC_PRIO_MAX+1] =
 350         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
 351
 352 /* 3-band FIFO queue: old style, but should be a bit faster than
 353    generic prio+fifo combination.
 354  */
 355
 356 #define PFIFO_FAST_BANDS 3
 357
 358 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
 359                                              struct Qdisc *qdisc)
 360 {
 361         struct sk_buff_head *list = qdisc_priv(qdisc);
 362         return list + prio2band[skb->priority & TC_PRIO_MAX];
 363 }
 364
 365 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
 366 {
 367         struct sk_buff_head *list = prio2list(skb, qdisc);
 368
 369         if (skb_queue_len(list) < qdisc_dev(qdisc)->tx_queue_len) {
 370                 qdisc->q.qlen++;
 371                 return __qdisc_enqueue_tail(skb, qdisc, list);
 372         }
 373
 374         return qdisc_drop(skb, qdisc);
 375 }
 376
 377 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
 378 {
 379         int prio;
 380         struct sk_buff_head *list = qdisc_priv(qdisc);
 381
 382         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 383                 if (!skb_queue_empty(list + prio)) {
 384                         qdisc->q.qlen--;
 385                         return __qdisc_dequeue_head(qdisc, list + prio);
 386                 }
 387         }
 388
 389         return NULL;
 390 }
 391
 392 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 393 {
 394         qdisc->q.qlen++;
 395         return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
 396 }
 397
 398 static void pfifo_fast_reset(struct Qdisc* qdisc)
 399 {
 400         int prio;
 401         struct sk_buff_head *list = qdisc_priv(qdisc);
 402
 403         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 404                 __qdisc_reset_queue(qdisc, list + prio);
 405
 406         qdisc->qstats.backlog = 0;
 407         qdisc->q.qlen = 0;
 408 }
 409
 410 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 411 {
 412         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 413
 414         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
 415         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 416         return skb->len;
 417
 418 nla_put_failure:
 419         return -1;
 420 }
 421
 422 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
 423 {
 424         int prio;
 425         struct sk_buff_head *list = qdisc_priv(qdisc);
 426
 427         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 428                 skb_queue_head_init(list + prio);
 429
 430         return 0;
 431 }
 432
 433 static struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 434         .id             =       "pfifo_fast",
 435         .priv_size      =       PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
 436         .enqueue        =       pfifo_fast_enqueue,
 437         .dequeue        =       pfifo_fast_dequeue,
 438         .requeue        =       pfifo_fast_requeue,
 439         .init           =       pfifo_fast_init,
 440         .reset          =       pfifo_fast_reset,
 441         .dump           =       pfifo_fast_dump,
 442         .owner          =       THIS_MODULE,
 443 };
 444
 445 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 446                           struct Qdisc_ops *ops)
 447 {
 448         void *p;
 449         struct Qdisc *sch;
 450         unsigned int size;
 451         int err = -ENOBUFS;
 452
 453         /* ensure that the Qdisc and the private data are 32-byte aligned */
 454         size = QDISC_ALIGN(sizeof(*sch));
 455         size += ops->priv_size + (QDISC_ALIGNTO - 1);
 456
 457         p = kzalloc(size, GFP_KERNEL);
 458         if (!p)
 459                 goto errout;
 460         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 461         sch->padded = (char *) sch - (char *) p;
 462
 463         INIT_LIST_HEAD(&sch->list);
 464         skb_queue_head_init(&sch->q);
 465         sch->ops = ops;
 466         sch->enqueue = ops->enqueue;
 467         sch->dequeue = ops->dequeue;
 468         sch->dev_queue = dev_queue;
 469         dev_hold(qdisc_dev(sch));
 470         atomic_set(&sch->refcnt, 1);
 471
 472         return sch;
 473 errout:
 474         return ERR_PTR(err);
 475 }
 476
 477 struct Qdisc * qdisc_create_dflt(struct net_device *dev,
 478                                  struct netdev_queue *dev_queue,
 479                                  struct Qdisc_ops *ops,
 480                                  unsigned int parentid)
 481 {
 482         struct Qdisc *sch;
 483
 484         sch = qdisc_alloc(dev_queue, ops);
 485         if (IS_ERR(sch))
 486                 goto errout;
 487         sch->parent = parentid;
 488
 489         if (!ops->init || ops->init(sch, NULL) == 0)
 490                 return sch;
 491
 492         qdisc_destroy(sch);
 493 errout:
 494         return NULL;
 495 }
 496 EXPORT_SYMBOL(qdisc_create_dflt);
 497
 498 /* Under queue->lock and BH! */
 499
 500 void qdisc_reset(struct Qdisc *qdisc)
 501 {
 502         const struct Qdisc_ops *ops = qdisc->ops;
 503
 504         if (ops->reset)
 505                 ops->reset(qdisc);
 506 }
 507 EXPORT_SYMBOL(qdisc_reset);
 508
 509 /* this is the rcu callback function to clean up a qdisc when there
 510  * are no further references to it */
 511
 512 static void __qdisc_destroy(struct rcu_head *head)
 513 {
 514         struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu);
 515         kfree((char *) qdisc - qdisc->padded);
 516 }
 517
 518 /* Under queue->lock and BH! */
 519
 520 void qdisc_destroy(struct Qdisc *qdisc)
 521 {
 522         const struct Qdisc_ops  *ops = qdisc->ops;
 523
 524         if (qdisc->flags & TCQ_F_BUILTIN ||
 525             !atomic_dec_and_test(&qdisc->refcnt))
 526                 return;
 527
 528         list_del(&qdisc->list);
 529         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
 530         if (ops->reset)
 531                 ops->reset(qdisc);
 532         if (ops->destroy)
 533                 ops->destroy(qdisc);
 534
 535         module_put(ops->owner);
 536         dev_put(qdisc_dev(qdisc));
 537         call_rcu(&qdisc->q_rcu, __qdisc_destroy);
 538 }
 539 EXPORT_SYMBOL(qdisc_destroy);
 540
 541 void dev_activate(struct net_device *dev)
 542 {
 543         struct netdev_queue *txq = &dev->tx_queue;
 544
 545         /* No queueing discipline is attached to device;
 546            create default one i.e. pfifo_fast for devices,
 547            which need queueing and noqueue_qdisc for
 548            virtual interfaces
 549          */
 550
 551         if (txq->qdisc_sleeping == &noop_qdisc) {
 552                 struct Qdisc *qdisc;
 553                 if (dev->tx_queue_len) {
 554                         qdisc = qdisc_create_dflt(dev, txq,
 555                                                   &pfifo_fast_ops,
 556                                                   TC_H_ROOT);
 557                         if (qdisc == NULL) {
 558                                 printk(KERN_INFO "%s: activation failed\n", dev->name);
 559                                 return;
 560                         }
 561                         list_add_tail(&qdisc->list, &txq->qdisc_list);
 562                 } else {
 563                         qdisc =  &noqueue_qdisc;
 564                 }
 565                 txq->qdisc_sleeping = qdisc;
 566         }
 567
 568         if (!netif_carrier_ok(dev))
 569                 /* Delay activation until next carrier-on event */
 570                 return;
 571
 572         spin_lock_bh(&txq->lock);
 573         rcu_assign_pointer(txq->qdisc, txq->qdisc_sleeping);
 574         if (txq->qdisc != &noqueue_qdisc) {
 575                 dev->trans_start = jiffies;
 576                 dev_watchdog_up(dev);
 577         }
 578         spin_unlock_bh(&txq->lock);
 579 }
 580
 581 static void dev_deactivate_queue(struct net_device *dev,
 582                                  struct netdev_queue *dev_queue,
 583                                  struct Qdisc *qdisc_default)
 584 {
 585         struct Qdisc *qdisc = dev_queue->qdisc;
 586
 587         if (qdisc) {
 588                 dev_queue->qdisc = qdisc_default;
 589                 qdisc_reset(qdisc);
 590         }
 591 }
 592
 593 void dev_deactivate(struct net_device *dev)
 594 {
 595         struct sk_buff *skb;
 596         int running;
 597
 598         spin_lock_bh(&dev->tx_queue.lock);
 599         dev_deactivate_queue(dev, &dev->tx_queue, &noop_qdisc);
 600
 601         skb = dev->gso_skb;
 602         dev->gso_skb = NULL;
 603         spin_unlock_bh(&dev->tx_queue.lock);
 604
 605         kfree_skb(skb);
 606
 607         dev_watchdog_down(dev);
 608
 609         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
 610         synchronize_rcu();
 611
 612         /* Wait for outstanding qdisc_run calls. */
 613         do {
 614                 while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
 615                         yield();
 616
 617                 /*
 618                  * Double-check inside queue lock to ensure that all effects
 619                  * of the queue run are visible when we return.
 620                  */
 621                 spin_lock_bh(&dev->tx_queue.lock);
 622                 running = test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
 623                 spin_unlock_bh(&dev->tx_queue.lock);
 624
 625                 /*
 626                  * The running flag should never be set at this point because
 627                  * we've already set dev->qdisc to noop_qdisc *inside* the same
 628                  * pair of spin locks.  That is, if any qdisc_run starts after
 629                  * our initial test it should see the noop_qdisc and then
 630                  * clear the RUNNING bit before dropping the queue lock.  So
 631                  * if it is set here then we've found a bug.
 632                  */
 633         } while (WARN_ON_ONCE(running));
 634 }
 635
 636 static void dev_init_scheduler_queue(struct net_device *dev,
 637                                      struct netdev_queue *dev_queue,
 638                                      struct Qdisc *qdisc)
 639 {
 640         dev_queue->qdisc = qdisc;
 641         dev_queue->qdisc_sleeping = qdisc;
 642         INIT_LIST_HEAD(&dev_queue->qdisc_list);
 643 }
 644
 645 void dev_init_scheduler(struct net_device *dev)
 646 {
 647         qdisc_lock_tree(dev);
 648         dev_init_scheduler_queue(dev, &dev->tx_queue, &noop_qdisc);
 649         dev_init_scheduler_queue(dev, &dev->rx_queue, NULL);
 650         qdisc_unlock_tree(dev);
 651
 652         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
 653 }
 654
 655 static void dev_shutdown_scheduler_queue(struct net_device *dev,
 656                                          struct netdev_queue *dev_queue,
 657                                          struct Qdisc *qdisc_default)
 658 {
 659         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
 660
 661         if (qdisc) {
 662                 dev_queue->qdisc = qdisc_default;
 663                 dev_queue->qdisc_sleeping = qdisc_default;
 664
 665                 qdisc_destroy(qdisc);
 666         }
 667 }
 668
 669 void dev_shutdown(struct net_device *dev)
 670 {
 671         qdisc_lock_tree(dev);
 672         dev_shutdown_scheduler_queue(dev, &dev->tx_queue, &noop_qdisc);
 673         dev_shutdown_scheduler_queue(dev, &dev->rx_queue, NULL);
 674         BUG_TRAP(!timer_pending(&dev->watchdog_timer));
 675         qdisc_unlock_tree(dev);
 676 }