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  * 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->rx_queue.lock)
  44 {
  45         unsigned int i;
  46
  47         local_bh_disable();
  48         for (i = 0; i < dev->num_tx_queues; i++) {
  49                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
  50                 spin_lock(&txq->lock);
  51         }
  52         spin_lock(&dev->rx_queue.lock);
  53 }
  54 EXPORT_SYMBOL(qdisc_lock_tree);
  55
  56 void qdisc_unlock_tree(struct net_device *dev)
  57         __releases(dev->rx_queue.lock)
  58 {
  59         unsigned int i;
  60
  61         spin_unlock(&dev->rx_queue.lock);
  62         for (i = 0; i < dev->num_tx_queues; i++) {
  63                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
  64                 spin_unlock(&txq->lock);
  65         }
  66         local_bh_enable();
  67 }
  68 EXPORT_SYMBOL(qdisc_unlock_tree);
  69
  70 static inline int qdisc_qlen(struct Qdisc *q)
  71 {
  72         return q->q.qlen;
  73 }
  74
  75 static inline int dev_requeue_skb(struct sk_buff *skb,
  76                                   struct netdev_queue *dev_queue,
  77                                   struct Qdisc *q)
  78 {
  79         if (unlikely(skb->next))
  80                 dev_queue->gso_skb = skb;
  81         else
  82                 q->ops->requeue(skb, q);
  83
  84         netif_schedule_queue(dev_queue);
  85         return 0;
  86 }
  87
  88 static inline struct sk_buff *dequeue_skb(struct netdev_queue *dev_queue,
  89                                           struct Qdisc *q)
  90 {
  91         struct sk_buff *skb;
  92
  93         if ((skb = dev_queue->gso_skb))
  94                 dev_queue->gso_skb = NULL;
  95         else
  96                 skb = q->dequeue(q);
  97
  98         return skb;
  99 }
 100
 101 static inline int handle_dev_cpu_collision(struct sk_buff *skb,
 102                                            struct netdev_queue *dev_queue,
 103                                            struct Qdisc *q)
 104 {
 105         int ret;
 106
 107         if (unlikely(dev_queue->xmit_lock_owner == smp_processor_id())) {
 108                 /*
 109                  * Same CPU holding the lock. It may be a transient
 110                  * configuration error, when hard_start_xmit() recurses. We
 111                  * detect it by checking xmit owner and drop the packet when
 112                  * deadloop is detected. Return OK to try the next skb.
 113                  */
 114                 kfree_skb(skb);
 115                 if (net_ratelimit())
 116                         printk(KERN_WARNING "Dead loop on netdevice %s, "
 117                                "fix it urgently!\n", dev_queue->dev->name);
 118                 ret = qdisc_qlen(q);
 119         } else {
 120                 /*
 121                  * Another cpu is holding lock, requeue & delay xmits for
 122                  * some time.
 123                  */
 124                 __get_cpu_var(netdev_rx_stat).cpu_collision++;
 125                 ret = dev_requeue_skb(skb, dev_queue, q);
 126         }
 127
 128         return ret;
 129 }
 130
 131 /*
 132  * NOTE: Called under queue->lock with locally disabled BH.
 133  *
 134  * __QUEUE_STATE_QDISC_RUNNING guarantees only one CPU can process
 135  * this queue at a time. queue->lock serializes queue accesses for
 136  * this queue AND txq->qdisc pointer itself.
 137  *
 138  *  netif_tx_lock serializes accesses to device driver.
 139  *
 140  *  queue->lock and netif_tx_lock are mutually exclusive,
 141  *  if one is grabbed, another must be free.
 142  *
 143  * Note, that this procedure can be called by a watchdog timer
 144  *
 145  * Returns to the caller:
 146  *                              0  - queue is empty or throttled.
 147  *                              >0 - queue is not empty.
 148  *
 149  */
 150 static inline int qdisc_restart(struct netdev_queue *txq)
 151 {
 152         struct Qdisc *q = txq->qdisc;
 153         int ret = NETDEV_TX_BUSY;
 154         struct net_device *dev;
 155         struct sk_buff *skb;
 156
 157         /* Dequeue packet */
 158         if (unlikely((skb = dequeue_skb(txq, q)) == NULL))
 159                 return 0;
 160
 161
 162         /* And release queue */
 163         spin_unlock(&txq->lock);
 164
 165         dev = txq->dev;
 166
 167         HARD_TX_LOCK(dev, txq, smp_processor_id());
 168         if (!netif_subqueue_stopped(dev, skb))
 169                 ret = dev_hard_start_xmit(skb, dev);
 170         HARD_TX_UNLOCK(dev, txq);
 171
 172         spin_lock(&txq->lock);
 173         q = txq->qdisc;
 174
 175         switch (ret) {
 176         case NETDEV_TX_OK:
 177                 /* Driver sent out skb successfully */
 178                 ret = qdisc_qlen(q);
 179                 break;
 180
 181         case NETDEV_TX_LOCKED:
 182                 /* Driver try lock failed */
 183                 ret = handle_dev_cpu_collision(skb, txq, q);
 184                 break;
 185
 186         default:
 187                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 188                 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
 189                         printk(KERN_WARNING "BUG %s code %d qlen %d\n",
 190                                dev->name, ret, q->q.qlen);
 191
 192                 ret = dev_requeue_skb(skb, txq, q);
 193                 break;
 194         }
 195
 196         return ret;
 197 }
 198
 199 void __qdisc_run(struct netdev_queue *txq)
 200 {
 201         struct net_device *dev = txq->dev;
 202         unsigned long start_time = jiffies;
 203
 204         while (qdisc_restart(txq)) {
 205                 if (netif_queue_stopped(dev))
 206                         break;
 207
 208                 /*
 209                  * Postpone processing if
 210                  * 1. another process needs the CPU;
 211                  * 2. we've been doing it for too long.
 212                  */
 213                 if (need_resched() || jiffies != start_time) {
 214                         netif_schedule_queue(txq);
 215                         break;
 216                 }
 217         }
 218
 219         clear_bit(__QUEUE_STATE_QDISC_RUNNING, &txq->state);
 220 }
 221
 222 static void dev_watchdog(unsigned long arg)
 223 {
 224         struct net_device *dev = (struct net_device *)arg;
 225
 226         netif_tx_lock(dev);
 227         if (!qdisc_tx_is_noop(dev)) {
 228                 if (netif_device_present(dev) &&
 229                     netif_running(dev) &&
 230                     netif_carrier_ok(dev)) {
 231                         int some_queue_stopped = 0;
 232                         unsigned int i;
 233
 234                         for (i = 0; i < dev->num_tx_queues; i++) {
 235                                 struct netdev_queue *txq;
 236
 237                                 txq = netdev_get_tx_queue(dev, i);
 238                                 if (netif_tx_queue_stopped(txq)) {
 239                                         some_queue_stopped = 1;
 240                                         break;
 241                                 }
 242                         }
 243
 244                         if (some_queue_stopped &&
 245                             time_after(jiffies, (dev->trans_start +
 246                                                  dev->watchdog_timeo))) {
 247                                 printk(KERN_INFO "NETDEV WATCHDOG: %s: "
 248                                        "transmit timed out\n",
 249                                        dev->name);
 250                                 dev->tx_timeout(dev);
 251                                 WARN_ON_ONCE(1);
 252                         }
 253                         if (!mod_timer(&dev->watchdog_timer,
 254                                        round_jiffies(jiffies +
 255                                                      dev->watchdog_timeo)))
 256                                 dev_hold(dev);
 257                 }
 258         }
 259         netif_tx_unlock(dev);
 260
 261         dev_put(dev);
 262 }
 263
 264 void __netdev_watchdog_up(struct net_device *dev)
 265 {
 266         if (dev->tx_timeout) {
 267                 if (dev->watchdog_timeo <= 0)
 268                         dev->watchdog_timeo = 5*HZ;
 269                 if (!mod_timer(&dev->watchdog_timer,
 270                                round_jiffies(jiffies + dev->watchdog_timeo)))
 271                         dev_hold(dev);
 272         }
 273 }
 274
 275 static void dev_watchdog_up(struct net_device *dev)
 276 {
 277         __netdev_watchdog_up(dev);
 278 }
 279
 280 static void dev_watchdog_down(struct net_device *dev)
 281 {
 282         netif_tx_lock_bh(dev);
 283         if (del_timer(&dev->watchdog_timer))
 284                 dev_put(dev);
 285         netif_tx_unlock_bh(dev);
 286 }
 287
 288 /**
 289  *      netif_carrier_on - set carrier
 290  *      @dev: network device
 291  *
 292  * Device has detected that carrier.
 293  */
 294 void netif_carrier_on(struct net_device *dev)
 295 {
 296         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 297                 linkwatch_fire_event(dev);
 298                 if (netif_running(dev))
 299                         __netdev_watchdog_up(dev);
 300         }
 301 }
 302 EXPORT_SYMBOL(netif_carrier_on);
 303
 304 /**
 305  *      netif_carrier_off - clear carrier
 306  *      @dev: network device
 307  *
 308  * Device has detected loss of carrier.
 309  */
 310 void netif_carrier_off(struct net_device *dev)
 311 {
 312         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state))
 313                 linkwatch_fire_event(dev);
 314 }
 315 EXPORT_SYMBOL(netif_carrier_off);
 316
 317 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 318    under all circumstances. It is difficult to invent anything faster or
 319    cheaper.
 320  */
 321
 322 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
 323 {
 324         kfree_skb(skb);
 325         return NET_XMIT_CN;
 326 }
 327
 328 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
 329 {
 330         return NULL;
 331 }
 332
 333 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 334 {
 335         if (net_ratelimit())
 336                 printk(KERN_DEBUG "%s deferred output. It is buggy.\n",
 337                        skb->dev->name);
 338         kfree_skb(skb);
 339         return NET_XMIT_CN;
 340 }
 341
 342 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 343         .id             =       "noop",
 344         .priv_size      =       0,
 345         .enqueue        =       noop_enqueue,
 346         .dequeue        =       noop_dequeue,
 347         .requeue        =       noop_requeue,
 348         .owner          =       THIS_MODULE,
 349 };
 350
 351 struct Qdisc noop_qdisc = {
 352         .enqueue        =       noop_enqueue,
 353         .dequeue        =       noop_dequeue,
 354         .flags          =       TCQ_F_BUILTIN,
 355         .ops            =       &noop_qdisc_ops,
 356         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
 357 };
 358 EXPORT_SYMBOL(noop_qdisc);
 359
 360 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 361         .id             =       "noqueue",
 362         .priv_size      =       0,
 363         .enqueue        =       noop_enqueue,
 364         .dequeue        =       noop_dequeue,
 365         .requeue        =       noop_requeue,
 366         .owner          =       THIS_MODULE,
 367 };
 368
 369 static struct Qdisc noqueue_qdisc = {
 370         .enqueue        =       NULL,
 371         .dequeue        =       noop_dequeue,
 372         .flags          =       TCQ_F_BUILTIN,
 373         .ops            =       &noqueue_qdisc_ops,
 374         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
 375 };
 376
 377
 378 static const u8 prio2band[TC_PRIO_MAX+1] =
 379         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
 380
 381 /* 3-band FIFO queue: old style, but should be a bit faster than
 382    generic prio+fifo combination.
 383  */
 384
 385 #define PFIFO_FAST_BANDS 3
 386
 387 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
 388                                              struct Qdisc *qdisc)
 389 {
 390         struct sk_buff_head *list = qdisc_priv(qdisc);
 391         return list + prio2band[skb->priority & TC_PRIO_MAX];
 392 }
 393
 394 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
 395 {
 396         struct sk_buff_head *list = prio2list(skb, qdisc);
 397
 398         if (skb_queue_len(list) < qdisc_dev(qdisc)->tx_queue_len) {
 399                 qdisc->q.qlen++;
 400                 return __qdisc_enqueue_tail(skb, qdisc, list);
 401         }
 402
 403         return qdisc_drop(skb, qdisc);
 404 }
 405
 406 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
 407 {
 408         int prio;
 409         struct sk_buff_head *list = qdisc_priv(qdisc);
 410
 411         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 412                 if (!skb_queue_empty(list + prio)) {
 413                         qdisc->q.qlen--;
 414                         return __qdisc_dequeue_head(qdisc, list + prio);
 415                 }
 416         }
 417
 418         return NULL;
 419 }
 420
 421 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 422 {
 423         qdisc->q.qlen++;
 424         return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
 425 }
 426
 427 static void pfifo_fast_reset(struct Qdisc* qdisc)
 428 {
 429         int prio;
 430         struct sk_buff_head *list = qdisc_priv(qdisc);
 431
 432         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 433                 __qdisc_reset_queue(qdisc, list + prio);
 434
 435         qdisc->qstats.backlog = 0;
 436         qdisc->q.qlen = 0;
 437 }
 438
 439 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 440 {
 441         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 442
 443         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
 444         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 445         return skb->len;
 446
 447 nla_put_failure:
 448         return -1;
 449 }
 450
 451 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
 452 {
 453         int prio;
 454         struct sk_buff_head *list = qdisc_priv(qdisc);
 455
 456         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 457                 skb_queue_head_init(list + prio);
 458
 459         return 0;
 460 }
 461
 462 static struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 463         .id             =       "pfifo_fast",
 464         .priv_size      =       PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
 465         .enqueue        =       pfifo_fast_enqueue,
 466         .dequeue        =       pfifo_fast_dequeue,
 467         .requeue        =       pfifo_fast_requeue,
 468         .init           =       pfifo_fast_init,
 469         .reset          =       pfifo_fast_reset,
 470         .dump           =       pfifo_fast_dump,
 471         .owner          =       THIS_MODULE,
 472 };
 473
 474 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 475                           struct Qdisc_ops *ops)
 476 {
 477         void *p;
 478         struct Qdisc *sch;
 479         unsigned int size;
 480         int err = -ENOBUFS;
 481
 482         /* ensure that the Qdisc and the private data are 32-byte aligned */
 483         size = QDISC_ALIGN(sizeof(*sch));
 484         size += ops->priv_size + (QDISC_ALIGNTO - 1);
 485
 486         p = kzalloc(size, GFP_KERNEL);
 487         if (!p)
 488                 goto errout;
 489         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 490         sch->padded = (char *) sch - (char *) p;
 491
 492         INIT_LIST_HEAD(&sch->list);
 493         skb_queue_head_init(&sch->q);
 494         sch->ops = ops;
 495         sch->enqueue = ops->enqueue;
 496         sch->dequeue = ops->dequeue;
 497         sch->dev_queue = dev_queue;
 498         dev_hold(qdisc_dev(sch));
 499         atomic_set(&sch->refcnt, 1);
 500
 501         return sch;
 502 errout:
 503         return ERR_PTR(err);
 504 }
 505
 506 struct Qdisc * qdisc_create_dflt(struct net_device *dev,
 507                                  struct netdev_queue *dev_queue,
 508                                  struct Qdisc_ops *ops,
 509                                  unsigned int parentid)
 510 {
 511         struct Qdisc *sch;
 512
 513         sch = qdisc_alloc(dev_queue, ops);
 514         if (IS_ERR(sch))
 515                 goto errout;
 516         sch->parent = parentid;
 517
 518         if (!ops->init || ops->init(sch, NULL) == 0)
 519                 return sch;
 520
 521         qdisc_destroy(sch);
 522 errout:
 523         return NULL;
 524 }
 525 EXPORT_SYMBOL(qdisc_create_dflt);
 526
 527 /* Under queue->lock and BH! */
 528
 529 void qdisc_reset(struct Qdisc *qdisc)
 530 {
 531         const struct Qdisc_ops *ops = qdisc->ops;
 532
 533         if (ops->reset)
 534                 ops->reset(qdisc);
 535 }
 536 EXPORT_SYMBOL(qdisc_reset);
 537
 538 /* this is the rcu callback function to clean up a qdisc when there
 539  * are no further references to it */
 540
 541 static void __qdisc_destroy(struct rcu_head *head)
 542 {
 543         struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu);
 544         kfree((char *) qdisc - qdisc->padded);
 545 }
 546
 547 /* Under queue->lock and BH! */
 548
 549 void qdisc_destroy(struct Qdisc *qdisc)
 550 {
 551         const struct Qdisc_ops  *ops = qdisc->ops;
 552
 553         if (qdisc->flags & TCQ_F_BUILTIN ||
 554             !atomic_dec_and_test(&qdisc->refcnt))
 555                 return;
 556
 557         list_del(&qdisc->list);
 558         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
 559         if (ops->reset)
 560                 ops->reset(qdisc);
 561         if (ops->destroy)
 562                 ops->destroy(qdisc);
 563
 564         module_put(ops->owner);
 565         dev_put(qdisc_dev(qdisc));
 566         call_rcu(&qdisc->q_rcu, __qdisc_destroy);
 567 }
 568 EXPORT_SYMBOL(qdisc_destroy);
 569
 570 static bool dev_all_qdisc_sleeping_noop(struct net_device *dev)
 571 {
 572         unsigned int i;
 573
 574         for (i = 0; i < dev->num_tx_queues; i++) {
 575                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 576
 577                 if (txq->qdisc_sleeping != &noop_qdisc)
 578                         return false;
 579         }
 580         return true;
 581 }
 582
 583 static void attach_one_default_qdisc(struct net_device *dev,
 584                                      struct netdev_queue *dev_queue,
 585                                      void *_unused)
 586 {
 587         struct Qdisc *qdisc;
 588
 589         if (dev->tx_queue_len) {
 590                 qdisc = qdisc_create_dflt(dev, dev_queue,
 591                                           &pfifo_fast_ops, TC_H_ROOT);
 592                 if (!qdisc) {
 593                         printk(KERN_INFO "%s: activation failed\n", dev->name);
 594                         return;
 595                 }
 596                 list_add_tail(&qdisc->list, &dev_queue->qdisc_list);
 597         } else {
 598                 qdisc =  &noqueue_qdisc;
 599         }
 600         dev_queue->qdisc_sleeping = qdisc;
 601 }
 602
 603 static void transition_one_qdisc(struct net_device *dev,
 604                                  struct netdev_queue *dev_queue,
 605                                  void *_need_watchdog)
 606 {
 607         int *need_watchdog_p = _need_watchdog;
 608
 609         spin_lock_bh(&dev_queue->lock);
 610         rcu_assign_pointer(dev_queue->qdisc, dev_queue->qdisc_sleeping);
 611         if (dev_queue->qdisc != &noqueue_qdisc)
 612                 *need_watchdog_p = 1;
 613         spin_unlock_bh(&dev_queue->lock);
 614 }
 615
 616 void dev_activate(struct net_device *dev)
 617 {
 618         int need_watchdog;
 619
 620         /* No queueing discipline is attached to device;
 621            create default one i.e. pfifo_fast for devices,
 622            which need queueing and noqueue_qdisc for
 623            virtual interfaces
 624          */
 625
 626         if (dev_all_qdisc_sleeping_noop(dev))
 627                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
 628
 629         if (!netif_carrier_ok(dev))
 630                 /* Delay activation until next carrier-on event */
 631                 return;
 632
 633         need_watchdog = 0;
 634         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
 635
 636         if (need_watchdog) {
 637                 dev->trans_start = jiffies;
 638                 dev_watchdog_up(dev);
 639         }
 640 }
 641
 642 static void dev_deactivate_queue(struct net_device *dev,
 643                                  struct netdev_queue *dev_queue,
 644                                  void *_qdisc_default)
 645 {
 646         struct Qdisc *qdisc_default = _qdisc_default;
 647         struct Qdisc *qdisc;
 648         struct sk_buff *skb;
 649
 650         spin_lock_bh(&dev_queue->lock);
 651
 652         qdisc = dev_queue->qdisc;
 653         if (qdisc) {
 654                 dev_queue->qdisc = qdisc_default;
 655                 qdisc_reset(qdisc);
 656         }
 657         skb = dev_queue->gso_skb;
 658         dev_queue->gso_skb = NULL;
 659
 660         spin_unlock_bh(&dev_queue->lock);
 661
 662         kfree_skb(skb);
 663 }
 664
 665 static bool some_qdisc_is_running(struct net_device *dev, int lock)
 666 {
 667         unsigned int i;
 668
 669         for (i = 0; i < dev->num_tx_queues; i++) {
 670                 struct netdev_queue *dev_queue;
 671                 int val;
 672
 673                 dev_queue = netdev_get_tx_queue(dev, i);
 674
 675                 if (lock)
 676                         spin_lock_bh(&dev_queue->lock);
 677
 678                 val = test_bit(__QUEUE_STATE_QDISC_RUNNING, &dev_queue->state);
 679
 680                 if (lock)
 681                         spin_unlock_bh(&dev_queue->lock);
 682
 683                 if (val)
 684                         return true;
 685         }
 686         return false;
 687 }
 688
 689 void dev_deactivate(struct net_device *dev)
 690 {
 691         bool running;
 692
 693         netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
 694
 695         dev_watchdog_down(dev);
 696
 697         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
 698         synchronize_rcu();
 699
 700         /* Wait for outstanding qdisc_run calls. */
 701         do {
 702                 while (some_qdisc_is_running(dev, 0))
 703                         yield();
 704
 705                 /*
 706                  * Double-check inside queue lock to ensure that all effects
 707                  * of the queue run are visible when we return.
 708                  */
 709                 running = some_qdisc_is_running(dev, 1);
 710
 711                 /*
 712                  * The running flag should never be set at this point because
 713                  * we've already set dev->qdisc to noop_qdisc *inside* the same
 714                  * pair of spin locks.  That is, if any qdisc_run starts after
 715                  * our initial test it should see the noop_qdisc and then
 716                  * clear the RUNNING bit before dropping the queue lock.  So
 717                  * if it is set here then we've found a bug.
 718                  */
 719         } while (WARN_ON_ONCE(running));
 720 }
 721
 722 static void dev_init_scheduler_queue(struct net_device *dev,
 723                                      struct netdev_queue *dev_queue,
 724                                      void *_qdisc)
 725 {
 726         struct Qdisc *qdisc = _qdisc;
 727
 728         dev_queue->qdisc = qdisc;
 729         dev_queue->qdisc_sleeping = qdisc;
 730         INIT_LIST_HEAD(&dev_queue->qdisc_list);
 731 }
 732
 733 void dev_init_scheduler(struct net_device *dev)
 734 {
 735         qdisc_lock_tree(dev);
 736         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
 737         dev_init_scheduler_queue(dev, &dev->rx_queue, NULL);
 738         qdisc_unlock_tree(dev);
 739
 740         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
 741 }
 742
 743 static void shutdown_scheduler_queue(struct net_device *dev,
 744                                      struct netdev_queue *dev_queue,
 745                                      void *_qdisc_default)
 746 {
 747         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
 748         struct Qdisc *qdisc_default = _qdisc_default;
 749
 750         if (qdisc) {
 751                 dev_queue->qdisc = qdisc_default;
 752                 dev_queue->qdisc_sleeping = qdisc_default;
 753
 754                 qdisc_destroy(qdisc);
 755         }
 756 }
 757
 758 void dev_shutdown(struct net_device *dev)
 759 {
 760         qdisc_lock_tree(dev);
 761         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
 762         shutdown_scheduler_queue(dev, &dev->rx_queue, NULL);
 763         BUG_TRAP(!timer_pending(&dev->watchdog_timer));
 764         qdisc_unlock_tree(dev);
 765 }