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 <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  * qdisc_lock(qdisc) spinlock.
  33  *
  34  * The idea is the following:
  35  * - enqueue, dequeue are serialized via qdisc root lock
  36  * - ingress filtering is also serialized via qdisc root lock
  37  * - updates to tree and tree walking are only done under the rtnl mutex.
  38  */
  39
  40 static inline int qdisc_qlen(struct Qdisc *q)
  41 {
  42         return q->q.qlen;
  43 }
  44
  45 static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
  46 {
  47         if (unlikely(skb->next))
  48                 q->gso_skb = skb;
  49         else
  50                 q->ops->requeue(skb, q);
  51
  52         __netif_schedule(q);
  53         return 0;
  54 }
  55
  56 static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
  57 {
  58         struct sk_buff *skb;
  59
  60         if ((skb = q->gso_skb))
  61                 q->gso_skb = NULL;
  62         else
  63                 skb = q->dequeue(q);
  64
  65         return skb;
  66 }
  67
  68 static inline int handle_dev_cpu_collision(struct sk_buff *skb,
  69                                            struct netdev_queue *dev_queue,
  70                                            struct Qdisc *q)
  71 {
  72         int ret;
  73
  74         if (unlikely(dev_queue->xmit_lock_owner == smp_processor_id())) {
  75                 /*
  76                  * Same CPU holding the lock. It may be a transient
  77                  * configuration error, when hard_start_xmit() recurses. We
  78                  * detect it by checking xmit owner and drop the packet when
  79                  * deadloop is detected. Return OK to try the next skb.
  80                  */
  81                 kfree_skb(skb);
  82                 if (net_ratelimit())
  83                         printk(KERN_WARNING "Dead loop on netdevice %s, "
  84                                "fix it urgently!\n", dev_queue->dev->name);
  85                 ret = qdisc_qlen(q);
  86         } else {
  87                 /*
  88                  * Another cpu is holding lock, requeue & delay xmits for
  89                  * some time.
  90                  */
  91                 __get_cpu_var(netdev_rx_stat).cpu_collision++;
  92                 ret = dev_requeue_skb(skb, q);
  93         }
  94
  95         return ret;
  96 }
  97
  98 /*
  99  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 100  *
 101  * __QDISC_STATE_RUNNING guarantees only one CPU can process
 102  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 103  * this queue.
 104  *
 105  *  netif_tx_lock serializes accesses to device driver.
 106  *
 107  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 108  *  if one is grabbed, another must be free.
 109  *
 110  * Note, that this procedure can be called by a watchdog timer
 111  *
 112  * Returns to the caller:
 113  *                              0  - queue is empty or throttled.
 114  *                              >0 - queue is not empty.
 115  *
 116  */
 117 static inline int qdisc_restart(struct Qdisc *q)
 118 {
 119         struct netdev_queue *txq;
 120         int ret = NETDEV_TX_BUSY;
 121         struct net_device *dev;
 122         spinlock_t *root_lock;
 123         struct sk_buff *skb;
 124
 125         /* Dequeue packet */
 126         if (unlikely((skb = dequeue_skb(q)) == NULL))
 127                 return 0;
 128
 129         root_lock = qdisc_lock(q);
 130
 131         /* And release qdisc */
 132         spin_unlock(root_lock);
 133
 134         dev = qdisc_dev(q);
 135         txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 136
 137         HARD_TX_LOCK(dev, txq, smp_processor_id());
 138         if (!netif_tx_queue_stopped(txq) &&
 139             !netif_tx_queue_frozen(txq))
 140                 ret = dev_hard_start_xmit(skb, dev, txq);
 141         HARD_TX_UNLOCK(dev, txq);
 142
 143         spin_lock(root_lock);
 144
 145         switch (ret) {
 146         case NETDEV_TX_OK:
 147                 /* Driver sent out skb successfully */
 148                 ret = qdisc_qlen(q);
 149                 break;
 150
 151         case NETDEV_TX_LOCKED:
 152                 /* Driver try lock failed */
 153                 ret = handle_dev_cpu_collision(skb, txq, q);
 154                 break;
 155
 156         default:
 157                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 158                 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
 159                         printk(KERN_WARNING "BUG %s code %d qlen %d\n",
 160                                dev->name, ret, q->q.qlen);
 161
 162                 ret = dev_requeue_skb(skb, q);
 163                 break;
 164         }
 165
 166         if (ret && (netif_tx_queue_stopped(txq) ||
 167                     netif_tx_queue_frozen(txq)))
 168                 ret = 0;
 169
 170         return ret;
 171 }
 172
 173 void __qdisc_run(struct Qdisc *q)
 174 {
 175         unsigned long start_time = jiffies;
 176
 177         while (qdisc_restart(q)) {
 178                 /*
 179                  * Postpone processing if
 180                  * 1. another process needs the CPU;
 181                  * 2. we've been doing it for too long.
 182                  */
 183                 if (need_resched() || jiffies != start_time) {
 184                         __netif_schedule(q);
 185                         break;
 186                 }
 187         }
 188
 189         clear_bit(__QDISC_STATE_RUNNING, &q->state);
 190 }
 191
 192 static void dev_watchdog(unsigned long arg)
 193 {
 194         struct net_device *dev = (struct net_device *)arg;
 195
 196         netif_tx_lock(dev);
 197         if (!qdisc_tx_is_noop(dev)) {
 198                 if (netif_device_present(dev) &&
 199                     netif_running(dev) &&
 200                     netif_carrier_ok(dev)) {
 201                         int some_queue_stopped = 0;
 202                         unsigned int i;
 203
 204                         for (i = 0; i < dev->num_tx_queues; i++) {
 205                                 struct netdev_queue *txq;
 206
 207                                 txq = netdev_get_tx_queue(dev, i);
 208                                 if (netif_tx_queue_stopped(txq)) {
 209                                         some_queue_stopped = 1;
 210                                         break;
 211                                 }
 212                         }
 213
 214                         if (some_queue_stopped &&
 215                             time_after(jiffies, (dev->trans_start +
 216                                                  dev->watchdog_timeo))) {
 217                                 char drivername[64];
 218                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit timed out\n",
 219                                        dev->name, netdev_drivername(dev, drivername, 64));
 220                                 dev->tx_timeout(dev);
 221                         }
 222                         if (!mod_timer(&dev->watchdog_timer,
 223                                        round_jiffies(jiffies +
 224                                                      dev->watchdog_timeo)))
 225                                 dev_hold(dev);
 226                 }
 227         }
 228         netif_tx_unlock(dev);
 229
 230         dev_put(dev);
 231 }
 232
 233 void __netdev_watchdog_up(struct net_device *dev)
 234 {
 235         if (dev->tx_timeout) {
 236                 if (dev->watchdog_timeo <= 0)
 237                         dev->watchdog_timeo = 5*HZ;
 238                 if (!mod_timer(&dev->watchdog_timer,
 239                                round_jiffies(jiffies + dev->watchdog_timeo)))
 240                         dev_hold(dev);
 241         }
 242 }
 243
 244 static void dev_watchdog_up(struct net_device *dev)
 245 {
 246         __netdev_watchdog_up(dev);
 247 }
 248
 249 static void dev_watchdog_down(struct net_device *dev)
 250 {
 251         netif_tx_lock_bh(dev);
 252         if (del_timer(&dev->watchdog_timer))
 253                 dev_put(dev);
 254         netif_tx_unlock_bh(dev);
 255 }
 256
 257 /**
 258  *      netif_carrier_on - set carrier
 259  *      @dev: network device
 260  *
 261  * Device has detected that carrier.
 262  */
 263 void netif_carrier_on(struct net_device *dev)
 264 {
 265         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 266                 linkwatch_fire_event(dev);
 267                 if (netif_running(dev))
 268                         __netdev_watchdog_up(dev);
 269         }
 270 }
 271 EXPORT_SYMBOL(netif_carrier_on);
 272
 273 /**
 274  *      netif_carrier_off - clear carrier
 275  *      @dev: network device
 276  *
 277  * Device has detected loss of carrier.
 278  */
 279 void netif_carrier_off(struct net_device *dev)
 280 {
 281         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state))
 282                 linkwatch_fire_event(dev);
 283 }
 284 EXPORT_SYMBOL(netif_carrier_off);
 285
 286 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 287    under all circumstances. It is difficult to invent anything faster or
 288    cheaper.
 289  */
 290
 291 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
 292 {
 293         kfree_skb(skb);
 294         return NET_XMIT_CN;
 295 }
 296
 297 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
 298 {
 299         return NULL;
 300 }
 301
 302 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 303 {
 304         if (net_ratelimit())
 305                 printk(KERN_DEBUG "%s deferred output. It is buggy.\n",
 306                        skb->dev->name);
 307         kfree_skb(skb);
 308         return NET_XMIT_CN;
 309 }
 310
 311 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 312         .id             =       "noop",
 313         .priv_size      =       0,
 314         .enqueue        =       noop_enqueue,
 315         .dequeue        =       noop_dequeue,
 316         .requeue        =       noop_requeue,
 317         .owner          =       THIS_MODULE,
 318 };
 319
 320 static struct netdev_queue noop_netdev_queue = {
 321         .qdisc          =       &noop_qdisc,
 322 };
 323
 324 struct Qdisc noop_qdisc = {
 325         .enqueue        =       noop_enqueue,
 326         .dequeue        =       noop_dequeue,
 327         .flags          =       TCQ_F_BUILTIN,
 328         .ops            =       &noop_qdisc_ops,
 329         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
 330         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 331         .dev_queue      =       &noop_netdev_queue,
 332 };
 333 EXPORT_SYMBOL(noop_qdisc);
 334
 335 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 336         .id             =       "noqueue",
 337         .priv_size      =       0,
 338         .enqueue        =       noop_enqueue,
 339         .dequeue        =       noop_dequeue,
 340         .requeue        =       noop_requeue,
 341         .owner          =       THIS_MODULE,
 342 };
 343
 344 static struct Qdisc noqueue_qdisc;
 345 static struct netdev_queue noqueue_netdev_queue = {
 346         .qdisc          =       &noqueue_qdisc,
 347 };
 348
 349 static struct Qdisc noqueue_qdisc = {
 350         .enqueue        =       NULL,
 351         .dequeue        =       noop_dequeue,
 352         .flags          =       TCQ_F_BUILTIN,
 353         .ops            =       &noqueue_qdisc_ops,
 354         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
 355         .q.lock         =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
 356         .dev_queue      =       &noqueue_netdev_queue,
 357 };
 358
 359
 360 static const u8 prio2band[TC_PRIO_MAX+1] =
 361         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
 362
 363 /* 3-band FIFO queue: old style, but should be a bit faster than
 364    generic prio+fifo combination.
 365  */
 366
 367 #define PFIFO_FAST_BANDS 3
 368
 369 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
 370                                              struct Qdisc *qdisc)
 371 {
 372         struct sk_buff_head *list = qdisc_priv(qdisc);
 373         return list + prio2band[skb->priority & TC_PRIO_MAX];
 374 }
 375
 376 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
 377 {
 378         struct sk_buff_head *list = prio2list(skb, qdisc);
 379
 380         if (skb_queue_len(list) < qdisc_dev(qdisc)->tx_queue_len) {
 381                 qdisc->q.qlen++;
 382                 return __qdisc_enqueue_tail(skb, qdisc, list);
 383         }
 384
 385         return qdisc_drop(skb, qdisc);
 386 }
 387
 388 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
 389 {
 390         int prio;
 391         struct sk_buff_head *list = qdisc_priv(qdisc);
 392
 393         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 394                 if (!skb_queue_empty(list + prio)) {
 395                         qdisc->q.qlen--;
 396                         return __qdisc_dequeue_head(qdisc, list + prio);
 397                 }
 398         }
 399
 400         return NULL;
 401 }
 402
 403 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 404 {
 405         qdisc->q.qlen++;
 406         return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
 407 }
 408
 409 static void pfifo_fast_reset(struct Qdisc* qdisc)
 410 {
 411         int prio;
 412         struct sk_buff_head *list = qdisc_priv(qdisc);
 413
 414         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 415                 __qdisc_reset_queue(qdisc, list + prio);
 416
 417         qdisc->qstats.backlog = 0;
 418         qdisc->q.qlen = 0;
 419 }
 420
 421 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 422 {
 423         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 424
 425         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
 426         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 427         return skb->len;
 428
 429 nla_put_failure:
 430         return -1;
 431 }
 432
 433 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
 434 {
 435         int prio;
 436         struct sk_buff_head *list = qdisc_priv(qdisc);
 437
 438         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 439                 skb_queue_head_init(list + prio);
 440
 441         return 0;
 442 }
 443
 444 static struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 445         .id             =       "pfifo_fast",
 446         .priv_size      =       PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
 447         .enqueue        =       pfifo_fast_enqueue,
 448         .dequeue        =       pfifo_fast_dequeue,
 449         .requeue        =       pfifo_fast_requeue,
 450         .init           =       pfifo_fast_init,
 451         .reset          =       pfifo_fast_reset,
 452         .dump           =       pfifo_fast_dump,
 453         .owner          =       THIS_MODULE,
 454 };
 455
 456 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 457                           struct Qdisc_ops *ops)
 458 {
 459         void *p;
 460         struct Qdisc *sch;
 461         unsigned int size;
 462         int err = -ENOBUFS;
 463
 464         /* ensure that the Qdisc and the private data are 32-byte aligned */
 465         size = QDISC_ALIGN(sizeof(*sch));
 466         size += ops->priv_size + (QDISC_ALIGNTO - 1);
 467
 468         p = kzalloc(size, GFP_KERNEL);
 469         if (!p)
 470                 goto errout;
 471         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 472         sch->padded = (char *) sch - (char *) p;
 473
 474         INIT_LIST_HEAD(&sch->list);
 475         skb_queue_head_init(&sch->q);
 476         sch->ops = ops;
 477         sch->enqueue = ops->enqueue;
 478         sch->dequeue = ops->dequeue;
 479         sch->dev_queue = dev_queue;
 480         dev_hold(qdisc_dev(sch));
 481         atomic_set(&sch->refcnt, 1);
 482
 483         return sch;
 484 errout:
 485         return ERR_PTR(err);
 486 }
 487
 488 struct Qdisc * qdisc_create_dflt(struct net_device *dev,
 489                                  struct netdev_queue *dev_queue,
 490                                  struct Qdisc_ops *ops,
 491                                  unsigned int parentid)
 492 {
 493         struct Qdisc *sch;
 494
 495         sch = qdisc_alloc(dev_queue, ops);
 496         if (IS_ERR(sch))
 497                 goto errout;
 498         sch->parent = parentid;
 499
 500         if (!ops->init || ops->init(sch, NULL) == 0)
 501                 return sch;
 502
 503         qdisc_destroy(sch);
 504 errout:
 505         return NULL;
 506 }
 507 EXPORT_SYMBOL(qdisc_create_dflt);
 508
 509 /* Under qdisc_lock(qdisc) and BH! */
 510
 511 void qdisc_reset(struct Qdisc *qdisc)
 512 {
 513         const struct Qdisc_ops *ops = qdisc->ops;
 514
 515         if (ops->reset)
 516                 ops->reset(qdisc);
 517 }
 518 EXPORT_SYMBOL(qdisc_reset);
 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 #ifdef CONFIG_NET_SCHED
 529         qdisc_list_del(qdisc);
 530
 531         qdisc_put_stab(qdisc->stab);
 532 #endif
 533         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
 534         if (ops->reset)
 535                 ops->reset(qdisc);
 536         if (ops->destroy)
 537                 ops->destroy(qdisc);
 538
 539         module_put(ops->owner);
 540         dev_put(qdisc_dev(qdisc));
 541
 542         kfree_skb(qdisc->gso_skb);
 543
 544         kfree((char *) qdisc - qdisc->padded);
 545 }
 546 EXPORT_SYMBOL(qdisc_destroy);
 547
 548 static bool dev_all_qdisc_sleeping_noop(struct net_device *dev)
 549 {
 550         unsigned int i;
 551
 552         for (i = 0; i < dev->num_tx_queues; i++) {
 553                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 554
 555                 if (txq->qdisc_sleeping != &noop_qdisc)
 556                         return false;
 557         }
 558         return true;
 559 }
 560
 561 static void attach_one_default_qdisc(struct net_device *dev,
 562                                      struct netdev_queue *dev_queue,
 563                                      void *_unused)
 564 {
 565         struct Qdisc *qdisc;
 566
 567         if (dev->tx_queue_len) {
 568                 qdisc = qdisc_create_dflt(dev, dev_queue,
 569                                           &pfifo_fast_ops, TC_H_ROOT);
 570                 if (!qdisc) {
 571                         printk(KERN_INFO "%s: activation failed\n", dev->name);
 572                         return;
 573                 }
 574         } else {
 575                 qdisc =  &noqueue_qdisc;
 576         }
 577         dev_queue->qdisc_sleeping = qdisc;
 578 }
 579
 580 static void transition_one_qdisc(struct net_device *dev,
 581                                  struct netdev_queue *dev_queue,
 582                                  void *_need_watchdog)
 583 {
 584         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
 585         int *need_watchdog_p = _need_watchdog;
 586
 587         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
 588                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
 589
 590         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
 591         if (need_watchdog_p && new_qdisc != &noqueue_qdisc)
 592                 *need_watchdog_p = 1;
 593 }
 594
 595 void dev_activate(struct net_device *dev)
 596 {
 597         int need_watchdog;
 598
 599         /* No queueing discipline is attached to device;
 600            create default one i.e. pfifo_fast for devices,
 601            which need queueing and noqueue_qdisc for
 602            virtual interfaces
 603          */
 604
 605         if (dev_all_qdisc_sleeping_noop(dev))
 606                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
 607
 608         if (!netif_carrier_ok(dev))
 609                 /* Delay activation until next carrier-on event */
 610                 return;
 611
 612         need_watchdog = 0;
 613         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
 614         transition_one_qdisc(dev, &dev->rx_queue, NULL);
 615
 616         if (need_watchdog) {
 617                 dev->trans_start = jiffies;
 618                 dev_watchdog_up(dev);
 619         }
 620 }
 621
 622 static void dev_deactivate_queue(struct net_device *dev,
 623                                  struct netdev_queue *dev_queue,
 624                                  void *_qdisc_default)
 625 {
 626         struct Qdisc *qdisc_default = _qdisc_default;
 627         struct Qdisc *qdisc;
 628
 629         qdisc = dev_queue->qdisc;
 630         if (qdisc) {
 631                 spin_lock_bh(qdisc_lock(qdisc));
 632
 633                 if (!(qdisc->flags & TCQ_F_BUILTIN))
 634                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
 635
 636                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
 637                 qdisc_reset(qdisc);
 638
 639                 spin_unlock_bh(qdisc_lock(qdisc));
 640         }
 641 }
 642
 643 static bool some_qdisc_is_busy(struct net_device *dev)
 644 {
 645         unsigned int i;
 646
 647         for (i = 0; i < dev->num_tx_queues; i++) {
 648                 struct netdev_queue *dev_queue;
 649                 spinlock_t *root_lock;
 650                 struct Qdisc *q;
 651                 int val;
 652
 653                 dev_queue = netdev_get_tx_queue(dev, i);
 654                 q = dev_queue->qdisc_sleeping;
 655                 root_lock = qdisc_lock(q);
 656
 657                 spin_lock_bh(root_lock);
 658
 659                 val = (test_bit(__QDISC_STATE_RUNNING, &q->state) ||
 660                        test_bit(__QDISC_STATE_SCHED, &q->state));
 661
 662                 spin_unlock_bh(root_lock);
 663
 664                 if (val)
 665                         return true;
 666         }
 667         return false;
 668 }
 669
 670 void dev_deactivate(struct net_device *dev)
 671 {
 672         netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
 673         dev_deactivate_queue(dev, &dev->rx_queue, &noop_qdisc);
 674
 675         dev_watchdog_down(dev);
 676
 677         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
 678         synchronize_rcu();
 679
 680         /* Wait for outstanding qdisc_run calls. */
 681         while (some_qdisc_is_busy(dev))
 682                 yield();
 683 }
 684
 685 static void dev_init_scheduler_queue(struct net_device *dev,
 686                                      struct netdev_queue *dev_queue,
 687                                      void *_qdisc)
 688 {
 689         struct Qdisc *qdisc = _qdisc;
 690
 691         dev_queue->qdisc = qdisc;
 692         dev_queue->qdisc_sleeping = qdisc;
 693 }
 694
 695 void dev_init_scheduler(struct net_device *dev)
 696 {
 697         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
 698         dev_init_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
 699
 700         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
 701 }
 702
 703 static void shutdown_scheduler_queue(struct net_device *dev,
 704                                      struct netdev_queue *dev_queue,
 705                                      void *_qdisc_default)
 706 {
 707         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
 708         struct Qdisc *qdisc_default = _qdisc_default;
 709
 710         if (qdisc) {
 711                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
 712                 dev_queue->qdisc_sleeping = qdisc_default;
 713
 714                 qdisc_destroy(qdisc);
 715         }
 716 }
 717
 718 void dev_shutdown(struct net_device *dev)
 719 {
 720         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
 721         shutdown_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
 722         WARN_ON(timer_pending(&dev->watchdog_timer));
 723 }