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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  * 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         q->gso_skb = skb;
  48         q->qstats.requeues++;
  49         __netif_schedule(q);
  50
  51         return 0;
  52 }
  53
  54 static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
  55 {
  56         struct sk_buff *skb = q->gso_skb;
  57
  58         if (unlikely(skb)) {
  59                 struct net_device *dev = qdisc_dev(q);
  60                 struct netdev_queue *txq;
  61
  62                 /* check the reason of requeuing without tx lock first */
  63                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
  64                 if (!netif_tx_queue_stopped(txq) && !netif_tx_queue_frozen(txq))
  65                         q->gso_skb = NULL;
  66                 else
  67                         skb = NULL;
  68         } else {
  69                 skb = q->dequeue(q);
  70         }
  71
  72         return skb;
  73 }
  74
  75 static inline int handle_dev_cpu_collision(struct sk_buff *skb,
  76                                            struct netdev_queue *dev_queue,
  77                                            struct Qdisc *q)
  78 {
  79         int ret;
  80
  81         if (unlikely(dev_queue->xmit_lock_owner == smp_processor_id())) {
  82                 /*
  83                  * Same CPU holding the lock. It may be a transient
  84                  * configuration error, when hard_start_xmit() recurses. We
  85                  * detect it by checking xmit owner and drop the packet when
  86                  * deadloop is detected. Return OK to try the next skb.
  87                  */
  88                 kfree_skb(skb);
  89                 if (net_ratelimit())
  90                         printk(KERN_WARNING "Dead loop on netdevice %s, "
  91                                "fix it urgently!\n", dev_queue->dev->name);
  92                 ret = qdisc_qlen(q);
  93         } else {
  94                 /*
  95                  * Another cpu is holding lock, requeue & delay xmits for
  96                  * some time.
  97                  */
  98                 __get_cpu_var(netdev_rx_stat).cpu_collision++;
  99                 ret = dev_requeue_skb(skb, q);
 100         }
 101
 102         return ret;
 103 }
 104
 105 /*
 106  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 107  *
 108  * __QDISC_STATE_RUNNING guarantees only one CPU can process
 109  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 110  * this queue.
 111  *
 112  *  netif_tx_lock serializes accesses to device driver.
 113  *
 114  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 115  *  if one is grabbed, another must be free.
 116  *
 117  * Note, that this procedure can be called by a watchdog timer
 118  *
 119  * Returns to the caller:
 120  *                              0  - queue is empty or throttled.
 121  *                              >0 - queue is not empty.
 122  *
 123  */
 124 static inline int qdisc_restart(struct Qdisc *q)
 125 {
 126         struct netdev_queue *txq;
 127         int ret = NETDEV_TX_BUSY;
 128         struct net_device *dev;
 129         spinlock_t *root_lock;
 130         struct sk_buff *skb;
 131
 132         /* Dequeue packet */
 133         if (unlikely((skb = dequeue_skb(q)) == NULL))
 134                 return 0;
 135
 136         root_lock = qdisc_lock(q);
 137
 138         /* And release qdisc */
 139         spin_unlock(root_lock);
 140
 141         dev = qdisc_dev(q);
 142         txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 143
 144         HARD_TX_LOCK(dev, txq, smp_processor_id());
 145         if (!netif_tx_queue_stopped(txq) &&
 146             !netif_tx_queue_frozen(txq))
 147                 ret = dev_hard_start_xmit(skb, dev, txq);
 148         HARD_TX_UNLOCK(dev, txq);
 149
 150         spin_lock(root_lock);
 151
 152         switch (ret) {
 153         case NETDEV_TX_OK:
 154                 /* Driver sent out skb successfully */
 155                 ret = qdisc_qlen(q);
 156                 break;
 157
 158         case NETDEV_TX_LOCKED:
 159                 /* Driver try lock failed */
 160                 ret = handle_dev_cpu_collision(skb, txq, q);
 161                 break;
 162
 163         default:
 164                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 165                 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
 166                         printk(KERN_WARNING "BUG %s code %d qlen %d\n",
 167                                dev->name, ret, q->q.qlen);
 168
 169                 ret = dev_requeue_skb(skb, q);
 170                 break;
 171         }
 172
 173         if (ret && (netif_tx_queue_stopped(txq) ||
 174                     netif_tx_queue_frozen(txq)))
 175                 ret = 0;
 176
 177         return ret;
 178 }
 179
 180 void __qdisc_run(struct Qdisc *q)
 181 {
 182         unsigned long start_time = jiffies;
 183
 184         while (qdisc_restart(q)) {
 185                 /*
 186                  * Postpone processing if
 187                  * 1. another process needs the CPU;
 188                  * 2. we've been doing it for too long.
 189                  */
 190                 if (need_resched() || jiffies != start_time) {
 191                         __netif_schedule(q);
 192                         break;
 193                 }
 194         }
 195
 196         clear_bit(__QDISC_STATE_RUNNING, &q->state);
 197 }
 198
 199 static void dev_watchdog(unsigned long arg)
 200 {
 201         struct net_device *dev = (struct net_device *)arg;
 202
 203         netif_tx_lock(dev);
 204         if (!qdisc_tx_is_noop(dev)) {
 205                 if (netif_device_present(dev) &&
 206                     netif_running(dev) &&
 207                     netif_carrier_ok(dev)) {
 208                         int some_queue_stopped = 0;
 209                         unsigned int i;
 210
 211                         for (i = 0; i < dev->num_tx_queues; i++) {
 212                                 struct netdev_queue *txq;
 213
 214                                 txq = netdev_get_tx_queue(dev, i);
 215                                 if (netif_tx_queue_stopped(txq)) {
 216                                         some_queue_stopped = 1;
 217                                         break;
 218                                 }
 219                         }
 220
 221                         if (some_queue_stopped &&
 222                             time_after(jiffies, (dev->trans_start +
 223                                                  dev->watchdog_timeo))) {
 224                                 char drivername[64];
 225                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit timed out\n",
 226                                        dev->name, netdev_drivername(dev, drivername, 64));
 227                                 dev->netdev_ops->ndo_tx_timeout(dev);
 228                         }
 229                         if (!mod_timer(&dev->watchdog_timer,
 230                                        round_jiffies(jiffies +
 231                                                      dev->watchdog_timeo)))
 232                                 dev_hold(dev);
 233                 }
 234         }
 235         netif_tx_unlock(dev);
 236
 237         dev_put(dev);
 238 }
 239
 240 void __netdev_watchdog_up(struct net_device *dev)
 241 {
 242         if (dev->netdev_ops->ndo_tx_timeout) {
 243                 if (dev->watchdog_timeo <= 0)
 244                         dev->watchdog_timeo = 5*HZ;
 245                 if (!mod_timer(&dev->watchdog_timer,
 246                                round_jiffies(jiffies + dev->watchdog_timeo)))
 247                         dev_hold(dev);
 248         }
 249 }
 250
 251 static void dev_watchdog_up(struct net_device *dev)
 252 {
 253         __netdev_watchdog_up(dev);
 254 }
 255
 256 static void dev_watchdog_down(struct net_device *dev)
 257 {
 258         netif_tx_lock_bh(dev);
 259         if (del_timer(&dev->watchdog_timer))
 260                 dev_put(dev);
 261         netif_tx_unlock_bh(dev);
 262 }
 263
 264 /**
 265  *      netif_carrier_on - set carrier
 266  *      @dev: network device
 267  *
 268  * Device has detected that carrier.
 269  */
 270 void netif_carrier_on(struct net_device *dev)
 271 {
 272         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 273                 if (dev->reg_state == NETREG_UNINITIALIZED)
 274                         return;
 275                 linkwatch_fire_event(dev);
 276                 if (netif_running(dev))
 277                         __netdev_watchdog_up(dev);
 278         }
 279 }
 280 EXPORT_SYMBOL(netif_carrier_on);
 281
 282 /**
 283  *      netif_carrier_off - clear carrier
 284  *      @dev: network device
 285  *
 286  * Device has detected loss of carrier.
 287  */
 288 void netif_carrier_off(struct net_device *dev)
 289 {
 290         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 291                 if (dev->reg_state == NETREG_UNINITIALIZED)
 292                         return;
 293                 linkwatch_fire_event(dev);
 294         }
 295 }
 296 EXPORT_SYMBOL(netif_carrier_off);
 297
 298 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 299    under all circumstances. It is difficult to invent anything faster or
 300    cheaper.
 301  */
 302
 303 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
 304 {
 305         kfree_skb(skb);
 306         return NET_XMIT_CN;
 307 }
 308
 309 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
 310 {
 311         return NULL;
 312 }
 313
 314 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 315         .id             =       "noop",
 316         .priv_size      =       0,
 317         .enqueue        =       noop_enqueue,
 318         .dequeue        =       noop_dequeue,
 319         .peek           =       noop_dequeue,
 320         .owner          =       THIS_MODULE,
 321 };
 322
 323 static struct netdev_queue noop_netdev_queue = {
 324         .qdisc          =       &noop_qdisc,
 325         .qdisc_sleeping =       &noop_qdisc,
 326 };
 327
 328 struct Qdisc noop_qdisc = {
 329         .enqueue        =       noop_enqueue,
 330         .dequeue        =       noop_dequeue,
 331         .flags          =       TCQ_F_BUILTIN,
 332         .ops            =       &noop_qdisc_ops,
 333         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
 334         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 335         .dev_queue      =       &noop_netdev_queue,
 336 };
 337 EXPORT_SYMBOL(noop_qdisc);
 338
 339 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 340         .id             =       "noqueue",
 341         .priv_size      =       0,
 342         .enqueue        =       noop_enqueue,
 343         .dequeue        =       noop_dequeue,
 344         .peek           =       noop_dequeue,
 345         .owner          =       THIS_MODULE,
 346 };
 347
 348 static struct Qdisc noqueue_qdisc;
 349 static struct netdev_queue noqueue_netdev_queue = {
 350         .qdisc          =       &noqueue_qdisc,
 351         .qdisc_sleeping =       &noqueue_qdisc,
 352 };
 353
 354 static struct Qdisc noqueue_qdisc = {
 355         .enqueue        =       NULL,
 356         .dequeue        =       noop_dequeue,
 357         .flags          =       TCQ_F_BUILTIN,
 358         .ops            =       &noqueue_qdisc_ops,
 359         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
 360         .q.lock         =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
 361         .dev_queue      =       &noqueue_netdev_queue,
 362 };
 363
 364
 365 static const u8 prio2band[TC_PRIO_MAX+1] =
 366         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
 367
 368 /* 3-band FIFO queue: old style, but should be a bit faster than
 369    generic prio+fifo combination.
 370  */
 371
 372 #define PFIFO_FAST_BANDS 3
 373
 374 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
 375                                              struct Qdisc *qdisc)
 376 {
 377         struct sk_buff_head *list = qdisc_priv(qdisc);
 378         return list + prio2band[skb->priority & TC_PRIO_MAX];
 379 }
 380
 381 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
 382 {
 383         struct sk_buff_head *list = prio2list(skb, qdisc);
 384
 385         if (skb_queue_len(list) < qdisc_dev(qdisc)->tx_queue_len) {
 386                 qdisc->q.qlen++;
 387                 return __qdisc_enqueue_tail(skb, qdisc, list);
 388         }
 389
 390         return qdisc_drop(skb, qdisc);
 391 }
 392
 393 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
 394 {
 395         int prio;
 396         struct sk_buff_head *list = qdisc_priv(qdisc);
 397
 398         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 399                 if (!skb_queue_empty(list + prio)) {
 400                         qdisc->q.qlen--;
 401                         return __qdisc_dequeue_head(qdisc, list + prio);
 402                 }
 403         }
 404
 405         return NULL;
 406 }
 407
 408 static struct sk_buff *pfifo_fast_peek(struct Qdisc* qdisc)
 409 {
 410         int prio;
 411         struct sk_buff_head *list = qdisc_priv(qdisc);
 412
 413         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 414                 if (!skb_queue_empty(list + prio))
 415                         return skb_peek(list + prio);
 416         }
 417
 418         return NULL;
 419 }
 420
 421 static void pfifo_fast_reset(struct Qdisc* qdisc)
 422 {
 423         int prio;
 424         struct sk_buff_head *list = qdisc_priv(qdisc);
 425
 426         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 427                 __qdisc_reset_queue(qdisc, list + prio);
 428
 429         qdisc->qstats.backlog = 0;
 430         qdisc->q.qlen = 0;
 431 }
 432
 433 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 434 {
 435         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 436
 437         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
 438         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 439         return skb->len;
 440
 441 nla_put_failure:
 442         return -1;
 443 }
 444
 445 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
 446 {
 447         int prio;
 448         struct sk_buff_head *list = qdisc_priv(qdisc);
 449
 450         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 451                 skb_queue_head_init(list + prio);
 452
 453         return 0;
 454 }
 455
 456 static struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 457         .id             =       "pfifo_fast",
 458         .priv_size      =       PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
 459         .enqueue        =       pfifo_fast_enqueue,
 460         .dequeue        =       pfifo_fast_dequeue,
 461         .peek           =       pfifo_fast_peek,
 462         .init           =       pfifo_fast_init,
 463         .reset          =       pfifo_fast_reset,
 464         .dump           =       pfifo_fast_dump,
 465         .owner          =       THIS_MODULE,
 466 };
 467
 468 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 469                           struct Qdisc_ops *ops)
 470 {
 471         void *p;
 472         struct Qdisc *sch;
 473         unsigned int size;
 474         int err = -ENOBUFS;
 475
 476         /* ensure that the Qdisc and the private data are 32-byte aligned */
 477         size = QDISC_ALIGN(sizeof(*sch));
 478         size += ops->priv_size + (QDISC_ALIGNTO - 1);
 479
 480         p = kzalloc(size, GFP_KERNEL);
 481         if (!p)
 482                 goto errout;
 483         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 484         sch->padded = (char *) sch - (char *) p;
 485
 486         INIT_LIST_HEAD(&sch->list);
 487         skb_queue_head_init(&sch->q);
 488         sch->ops = ops;
 489         sch->enqueue = ops->enqueue;
 490         sch->dequeue = ops->dequeue;
 491         sch->dev_queue = dev_queue;
 492         dev_hold(qdisc_dev(sch));
 493         atomic_set(&sch->refcnt, 1);
 494
 495         return sch;
 496 errout:
 497         return ERR_PTR(err);
 498 }
 499
 500 struct Qdisc * qdisc_create_dflt(struct net_device *dev,
 501                                  struct netdev_queue *dev_queue,
 502                                  struct Qdisc_ops *ops,
 503                                  unsigned int parentid)
 504 {
 505         struct Qdisc *sch;
 506
 507         sch = qdisc_alloc(dev_queue, ops);
 508         if (IS_ERR(sch))
 509                 goto errout;
 510         sch->parent = parentid;
 511
 512         if (!ops->init || ops->init(sch, NULL) == 0)
 513                 return sch;
 514
 515         qdisc_destroy(sch);
 516 errout:
 517         return NULL;
 518 }
 519 EXPORT_SYMBOL(qdisc_create_dflt);
 520
 521 /* Under qdisc_lock(qdisc) and BH! */
 522
 523 void qdisc_reset(struct Qdisc *qdisc)
 524 {
 525         const struct Qdisc_ops *ops = qdisc->ops;
 526
 527         if (ops->reset)
 528                 ops->reset(qdisc);
 529
 530         kfree_skb(qdisc->gso_skb);
 531         qdisc->gso_skb = NULL;
 532 }
 533 EXPORT_SYMBOL(qdisc_reset);
 534
 535 void qdisc_destroy(struct Qdisc *qdisc)
 536 {
 537         const struct Qdisc_ops  *ops = qdisc->ops;
 538
 539         if (qdisc->flags & TCQ_F_BUILTIN ||
 540             !atomic_dec_and_test(&qdisc->refcnt))
 541                 return;
 542
 543 #ifdef CONFIG_NET_SCHED
 544         qdisc_list_del(qdisc);
 545
 546         qdisc_put_stab(qdisc->stab);
 547 #endif
 548         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
 549         if (ops->reset)
 550                 ops->reset(qdisc);
 551         if (ops->destroy)
 552                 ops->destroy(qdisc);
 553
 554         module_put(ops->owner);
 555         dev_put(qdisc_dev(qdisc));
 556
 557         kfree_skb(qdisc->gso_skb);
 558         kfree((char *) qdisc - qdisc->padded);
 559 }
 560 EXPORT_SYMBOL(qdisc_destroy);
 561
 562 static bool dev_all_qdisc_sleeping_noop(struct net_device *dev)
 563 {
 564         unsigned int i;
 565
 566         for (i = 0; i < dev->num_tx_queues; i++) {
 567                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 568
 569                 if (txq->qdisc_sleeping != &noop_qdisc)
 570                         return false;
 571         }
 572         return true;
 573 }
 574
 575 static void attach_one_default_qdisc(struct net_device *dev,
 576                                      struct netdev_queue *dev_queue,
 577                                      void *_unused)
 578 {
 579         struct Qdisc *qdisc;
 580
 581         if (dev->tx_queue_len) {
 582                 qdisc = qdisc_create_dflt(dev, dev_queue,
 583                                           &pfifo_fast_ops, TC_H_ROOT);
 584                 if (!qdisc) {
 585                         printk(KERN_INFO "%s: activation failed\n", dev->name);
 586                         return;
 587                 }
 588         } else {
 589                 qdisc =  &noqueue_qdisc;
 590         }
 591         dev_queue->qdisc_sleeping = qdisc;
 592 }
 593
 594 static void transition_one_qdisc(struct net_device *dev,
 595                                  struct netdev_queue *dev_queue,
 596                                  void *_need_watchdog)
 597 {
 598         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
 599         int *need_watchdog_p = _need_watchdog;
 600
 601         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
 602                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
 603
 604         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
 605         if (need_watchdog_p && new_qdisc != &noqueue_qdisc)
 606                 *need_watchdog_p = 1;
 607 }
 608
 609 void dev_activate(struct net_device *dev)
 610 {
 611         int need_watchdog;
 612
 613         /* No queueing discipline is attached to device;
 614            create default one i.e. pfifo_fast for devices,
 615            which need queueing and noqueue_qdisc for
 616            virtual interfaces
 617          */
 618
 619         if (dev_all_qdisc_sleeping_noop(dev))
 620                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
 621
 622         if (!netif_carrier_ok(dev))
 623                 /* Delay activation until next carrier-on event */
 624                 return;
 625
 626         need_watchdog = 0;
 627         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
 628         transition_one_qdisc(dev, &dev->rx_queue, NULL);
 629
 630         if (need_watchdog) {
 631                 dev->trans_start = jiffies;
 632                 dev_watchdog_up(dev);
 633         }
 634 }
 635
 636 static void dev_deactivate_queue(struct net_device *dev,
 637                                  struct netdev_queue *dev_queue,
 638                                  void *_qdisc_default)
 639 {
 640         struct Qdisc *qdisc_default = _qdisc_default;
 641         struct Qdisc *qdisc;
 642
 643         qdisc = dev_queue->qdisc;
 644         if (qdisc) {
 645                 spin_lock_bh(qdisc_lock(qdisc));
 646
 647                 if (!(qdisc->flags & TCQ_F_BUILTIN))
 648                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
 649
 650                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
 651                 qdisc_reset(qdisc);
 652
 653                 spin_unlock_bh(qdisc_lock(qdisc));
 654         }
 655 }
 656
 657 static bool some_qdisc_is_busy(struct net_device *dev)
 658 {
 659         unsigned int i;
 660
 661         for (i = 0; i < dev->num_tx_queues; i++) {
 662                 struct netdev_queue *dev_queue;
 663                 spinlock_t *root_lock;
 664                 struct Qdisc *q;
 665                 int val;
 666
 667                 dev_queue = netdev_get_tx_queue(dev, i);
 668                 q = dev_queue->qdisc_sleeping;
 669                 root_lock = qdisc_lock(q);
 670
 671                 spin_lock_bh(root_lock);
 672
 673                 val = (test_bit(__QDISC_STATE_RUNNING, &q->state) ||
 674                        test_bit(__QDISC_STATE_SCHED, &q->state));
 675
 676                 spin_unlock_bh(root_lock);
 677
 678                 if (val)
 679                         return true;
 680         }
 681         return false;
 682 }
 683
 684 void dev_deactivate(struct net_device *dev)
 685 {
 686         netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
 687         dev_deactivate_queue(dev, &dev->rx_queue, &noop_qdisc);
 688
 689         dev_watchdog_down(dev);
 690
 691         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
 692         synchronize_rcu();
 693
 694         /* Wait for outstanding qdisc_run calls. */
 695         while (some_qdisc_is_busy(dev))
 696                 yield();
 697 }
 698
 699 static void dev_init_scheduler_queue(struct net_device *dev,
 700                                      struct netdev_queue *dev_queue,
 701                                      void *_qdisc)
 702 {
 703         struct Qdisc *qdisc = _qdisc;
 704
 705         dev_queue->qdisc = qdisc;
 706         dev_queue->qdisc_sleeping = qdisc;
 707 }
 708
 709 void dev_init_scheduler(struct net_device *dev)
 710 {
 711         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
 712         dev_init_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
 713
 714         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
 715 }
 716
 717 static void shutdown_scheduler_queue(struct net_device *dev,
 718                                      struct netdev_queue *dev_queue,
 719                                      void *_qdisc_default)
 720 {
 721         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
 722         struct Qdisc *qdisc_default = _qdisc_default;
 723
 724         if (qdisc) {
 725                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
 726                 dev_queue->qdisc_sleeping = qdisc_default;
 727
 728                 qdisc_destroy(qdisc);
 729         }
 730 }
 731
 732 void dev_shutdown(struct net_device *dev)
 733 {
 734         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
 735         shutdown_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
 736         WARN_ON(timer_pending(&dev->watchdog_timer));
 737 }