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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->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, txq);
 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         unsigned long start_time = jiffies;
 202
 203         while (qdisc_restart(txq)) {
 204                 if (netif_tx_queue_stopped(txq))
 205                         break;
 206
 207                 /*
 208                  * Postpone processing if
 209                  * 1. another process needs the CPU;
 210                  * 2. we've been doing it for too long.
 211                  */
 212                 if (need_resched() || jiffies != start_time) {
 213                         netif_schedule_queue(txq);
 214                         break;
 215                 }
 216         }
 217
 218         clear_bit(__QUEUE_STATE_QDISC_RUNNING, &txq->state);
 219 }
 220
 221 static void dev_watchdog(unsigned long arg)
 222 {
 223         struct net_device *dev = (struct net_device *)arg;
 224
 225         netif_tx_lock(dev);
 226         if (!qdisc_tx_is_noop(dev)) {
 227                 if (netif_device_present(dev) &&
 228                     netif_running(dev) &&
 229                     netif_carrier_ok(dev)) {
 230                         int some_queue_stopped = 0;
 231                         unsigned int i;
 232
 233                         for (i = 0; i < dev->num_tx_queues; i++) {
 234                                 struct netdev_queue *txq;
 235
 236                                 txq = netdev_get_tx_queue(dev, i);
 237                                 if (netif_tx_queue_stopped(txq)) {
 238                                         some_queue_stopped = 1;
 239                                         break;
 240                                 }
 241                         }
 242
 243                         if (some_queue_stopped &&
 244                             time_after(jiffies, (dev->trans_start +
 245                                                  dev->watchdog_timeo))) {
 246                                 printk(KERN_INFO "NETDEV WATCHDOG: %s: "
 247                                        "transmit timed out\n",
 248                                        dev->name);
 249                                 dev->tx_timeout(dev);
 250                                 WARN_ON_ONCE(1);
 251                         }
 252                         if (!mod_timer(&dev->watchdog_timer,
 253                                        round_jiffies(jiffies +
 254                                                      dev->watchdog_timeo)))
 255                                 dev_hold(dev);
 256                 }
 257         }
 258         netif_tx_unlock(dev);
 259
 260         dev_put(dev);
 261 }
 262
 263 void __netdev_watchdog_up(struct net_device *dev)
 264 {
 265         if (dev->tx_timeout) {
 266                 if (dev->watchdog_timeo <= 0)
 267                         dev->watchdog_timeo = 5*HZ;
 268                 if (!mod_timer(&dev->watchdog_timer,
 269                                round_jiffies(jiffies + dev->watchdog_timeo)))
 270                         dev_hold(dev);
 271         }
 272 }
 273
 274 static void dev_watchdog_up(struct net_device *dev)
 275 {
 276         __netdev_watchdog_up(dev);
 277 }
 278
 279 static void dev_watchdog_down(struct net_device *dev)
 280 {
 281         netif_tx_lock_bh(dev);
 282         if (del_timer(&dev->watchdog_timer))
 283                 dev_put(dev);
 284         netif_tx_unlock_bh(dev);
 285 }
 286
 287 /**
 288  *      netif_carrier_on - set carrier
 289  *      @dev: network device
 290  *
 291  * Device has detected that carrier.
 292  */
 293 void netif_carrier_on(struct net_device *dev)
 294 {
 295         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 296                 linkwatch_fire_event(dev);
 297                 if (netif_running(dev))
 298                         __netdev_watchdog_up(dev);
 299         }
 300 }
 301 EXPORT_SYMBOL(netif_carrier_on);
 302
 303 /**
 304  *      netif_carrier_off - clear carrier
 305  *      @dev: network device
 306  *
 307  * Device has detected loss of carrier.
 308  */
 309 void netif_carrier_off(struct net_device *dev)
 310 {
 311         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state))
 312                 linkwatch_fire_event(dev);
 313 }
 314 EXPORT_SYMBOL(netif_carrier_off);
 315
 316 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 317    under all circumstances. It is difficult to invent anything faster or
 318    cheaper.
 319  */
 320
 321 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
 322 {
 323         kfree_skb(skb);
 324         return NET_XMIT_CN;
 325 }
 326
 327 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
 328 {
 329         return NULL;
 330 }
 331
 332 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 333 {
 334         if (net_ratelimit())
 335                 printk(KERN_DEBUG "%s deferred output. It is buggy.\n",
 336                        skb->dev->name);
 337         kfree_skb(skb);
 338         return NET_XMIT_CN;
 339 }
 340
 341 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 342         .id             =       "noop",
 343         .priv_size      =       0,
 344         .enqueue        =       noop_enqueue,
 345         .dequeue        =       noop_dequeue,
 346         .requeue        =       noop_requeue,
 347         .owner          =       THIS_MODULE,
 348 };
 349
 350 struct Qdisc noop_qdisc = {
 351         .enqueue        =       noop_enqueue,
 352         .dequeue        =       noop_dequeue,
 353         .flags          =       TCQ_F_BUILTIN,
 354         .ops            =       &noop_qdisc_ops,
 355         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
 356 };
 357 EXPORT_SYMBOL(noop_qdisc);
 358
 359 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 360         .id             =       "noqueue",
 361         .priv_size      =       0,
 362         .enqueue        =       noop_enqueue,
 363         .dequeue        =       noop_dequeue,
 364         .requeue        =       noop_requeue,
 365         .owner          =       THIS_MODULE,
 366 };
 367
 368 static struct Qdisc noqueue_qdisc = {
 369         .enqueue        =       NULL,
 370         .dequeue        =       noop_dequeue,
 371         .flags          =       TCQ_F_BUILTIN,
 372         .ops            =       &noqueue_qdisc_ops,
 373         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
 374 };
 375
 376
 377 static const u8 prio2band[TC_PRIO_MAX+1] =
 378         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
 379
 380 /* 3-band FIFO queue: old style, but should be a bit faster than
 381    generic prio+fifo combination.
 382  */
 383
 384 #define PFIFO_FAST_BANDS 3
 385
 386 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
 387                                              struct Qdisc *qdisc)
 388 {
 389         struct sk_buff_head *list = qdisc_priv(qdisc);
 390         return list + prio2band[skb->priority & TC_PRIO_MAX];
 391 }
 392
 393 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
 394 {
 395         struct sk_buff_head *list = prio2list(skb, qdisc);
 396
 397         if (skb_queue_len(list) < qdisc_dev(qdisc)->tx_queue_len) {
 398                 qdisc->q.qlen++;
 399                 return __qdisc_enqueue_tail(skb, qdisc, list);
 400         }
 401
 402         return qdisc_drop(skb, qdisc);
 403 }
 404
 405 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
 406 {
 407         int prio;
 408         struct sk_buff_head *list = qdisc_priv(qdisc);
 409
 410         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 411                 if (!skb_queue_empty(list + prio)) {
 412                         qdisc->q.qlen--;
 413                         return __qdisc_dequeue_head(qdisc, list + prio);
 414                 }
 415         }
 416
 417         return NULL;
 418 }
 419
 420 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
 421 {
 422         qdisc->q.qlen++;
 423         return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
 424 }
 425
 426 static void pfifo_fast_reset(struct Qdisc* qdisc)
 427 {
 428         int prio;
 429         struct sk_buff_head *list = qdisc_priv(qdisc);
 430
 431         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 432                 __qdisc_reset_queue(qdisc, list + prio);
 433
 434         qdisc->qstats.backlog = 0;
 435         qdisc->q.qlen = 0;
 436 }
 437
 438 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 439 {
 440         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 441
 442         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
 443         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 444         return skb->len;
 445
 446 nla_put_failure:
 447         return -1;
 448 }
 449
 450 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
 451 {
 452         int prio;
 453         struct sk_buff_head *list = qdisc_priv(qdisc);
 454
 455         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 456                 skb_queue_head_init(list + prio);
 457
 458         return 0;
 459 }
 460
 461 static struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 462         .id             =       "pfifo_fast",
 463         .priv_size      =       PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
 464         .enqueue        =       pfifo_fast_enqueue,
 465         .dequeue        =       pfifo_fast_dequeue,
 466         .requeue        =       pfifo_fast_requeue,
 467         .init           =       pfifo_fast_init,
 468         .reset          =       pfifo_fast_reset,
 469         .dump           =       pfifo_fast_dump,
 470         .owner          =       THIS_MODULE,
 471 };
 472
 473 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 474                           struct Qdisc_ops *ops)
 475 {
 476         void *p;
 477         struct Qdisc *sch;
 478         unsigned int size;
 479         int err = -ENOBUFS;
 480
 481         /* ensure that the Qdisc and the private data are 32-byte aligned */
 482         size = QDISC_ALIGN(sizeof(*sch));
 483         size += ops->priv_size + (QDISC_ALIGNTO - 1);
 484
 485         p = kzalloc(size, GFP_KERNEL);
 486         if (!p)
 487                 goto errout;
 488         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 489         sch->padded = (char *) sch - (char *) p;
 490
 491         INIT_LIST_HEAD(&sch->list);
 492         skb_queue_head_init(&sch->q);
 493         sch->ops = ops;
 494         sch->enqueue = ops->enqueue;
 495         sch->dequeue = ops->dequeue;
 496         sch->dev_queue = dev_queue;
 497         dev_hold(qdisc_dev(sch));
 498         atomic_set(&sch->refcnt, 1);
 499
 500         return sch;
 501 errout:
 502         return ERR_PTR(err);
 503 }
 504
 505 struct Qdisc * qdisc_create_dflt(struct net_device *dev,
 506                                  struct netdev_queue *dev_queue,
 507                                  struct Qdisc_ops *ops,
 508                                  unsigned int parentid)
 509 {
 510         struct Qdisc *sch;
 511
 512         sch = qdisc_alloc(dev_queue, ops);
 513         if (IS_ERR(sch))
 514                 goto errout;
 515         sch->parent = parentid;
 516
 517         if (!ops->init || ops->init(sch, NULL) == 0)
 518                 return sch;
 519
 520         qdisc_destroy(sch);
 521 errout:
 522         return NULL;
 523 }
 524 EXPORT_SYMBOL(qdisc_create_dflt);
 525
 526 /* Under queue->lock and BH! */
 527
 528 void qdisc_reset(struct Qdisc *qdisc)
 529 {
 530         const struct Qdisc_ops *ops = qdisc->ops;
 531
 532         if (ops->reset)
 533                 ops->reset(qdisc);
 534 }
 535 EXPORT_SYMBOL(qdisc_reset);
 536
 537 /* this is the rcu callback function to clean up a qdisc when there
 538  * are no further references to it */
 539
 540 static void __qdisc_destroy(struct rcu_head *head)
 541 {
 542         struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu);
 543         kfree((char *) qdisc - qdisc->padded);
 544 }
 545
 546 /* Under queue->lock and BH! */
 547
 548 void qdisc_destroy(struct Qdisc *qdisc)
 549 {
 550         const struct Qdisc_ops  *ops = qdisc->ops;
 551
 552         if (qdisc->flags & TCQ_F_BUILTIN ||
 553             !atomic_dec_and_test(&qdisc->refcnt))
 554                 return;
 555
 556         list_del(&qdisc->list);
 557         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
 558         if (ops->reset)
 559                 ops->reset(qdisc);
 560         if (ops->destroy)
 561                 ops->destroy(qdisc);
 562
 563         module_put(ops->owner);
 564         dev_put(qdisc_dev(qdisc));
 565         call_rcu(&qdisc->q_rcu, __qdisc_destroy);
 566 }
 567 EXPORT_SYMBOL(qdisc_destroy);
 568
 569 static bool dev_all_qdisc_sleeping_noop(struct net_device *dev)
 570 {
 571         unsigned int i;
 572
 573         for (i = 0; i < dev->num_tx_queues; i++) {
 574                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 575
 576                 if (txq->qdisc_sleeping != &noop_qdisc)
 577                         return false;
 578         }
 579         return true;
 580 }
 581
 582 static void attach_one_default_qdisc(struct net_device *dev,
 583                                      struct netdev_queue *dev_queue,
 584                                      void *_unused)
 585 {
 586         struct Qdisc *qdisc;
 587
 588         if (dev->tx_queue_len) {
 589                 qdisc = qdisc_create_dflt(dev, dev_queue,
 590                                           &pfifo_fast_ops, TC_H_ROOT);
 591                 if (!qdisc) {
 592                         printk(KERN_INFO "%s: activation failed\n", dev->name);
 593                         return;
 594                 }
 595                 list_add_tail(&qdisc->list, &dev_queue->qdisc_list);
 596         } else {
 597                 qdisc =  &noqueue_qdisc;
 598         }
 599         dev_queue->qdisc_sleeping = qdisc;
 600 }
 601
 602 static void transition_one_qdisc(struct net_device *dev,
 603                                  struct netdev_queue *dev_queue,
 604                                  void *_need_watchdog)
 605 {
 606         int *need_watchdog_p = _need_watchdog;
 607
 608         spin_lock_bh(&dev_queue->lock);
 609         rcu_assign_pointer(dev_queue->qdisc, dev_queue->qdisc_sleeping);
 610         if (dev_queue->qdisc != &noqueue_qdisc)
 611                 *need_watchdog_p = 1;
 612         spin_unlock_bh(&dev_queue->lock);
 613 }
 614
 615 void dev_activate(struct net_device *dev)
 616 {
 617         int need_watchdog;
 618
 619         /* No queueing discipline is attached to device;
 620            create default one i.e. pfifo_fast for devices,
 621            which need queueing and noqueue_qdisc for
 622            virtual interfaces
 623          */
 624
 625         if (dev_all_qdisc_sleeping_noop(dev))
 626                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
 627
 628         if (!netif_carrier_ok(dev))
 629                 /* Delay activation until next carrier-on event */
 630                 return;
 631
 632         need_watchdog = 0;
 633         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
 634
 635         if (need_watchdog) {
 636                 dev->trans_start = jiffies;
 637                 dev_watchdog_up(dev);
 638         }
 639 }
 640
 641 static void dev_deactivate_queue(struct net_device *dev,
 642                                  struct netdev_queue *dev_queue,
 643                                  void *_qdisc_default)
 644 {
 645         struct Qdisc *qdisc_default = _qdisc_default;
 646         struct Qdisc *qdisc;
 647         struct sk_buff *skb;
 648
 649         spin_lock_bh(&dev_queue->lock);
 650
 651         qdisc = dev_queue->qdisc;
 652         if (qdisc) {
 653                 dev_queue->qdisc = qdisc_default;
 654                 qdisc_reset(qdisc);
 655         }
 656         skb = dev_queue->gso_skb;
 657         dev_queue->gso_skb = NULL;
 658
 659         spin_unlock_bh(&dev_queue->lock);
 660
 661         kfree_skb(skb);
 662 }
 663
 664 static bool some_qdisc_is_running(struct net_device *dev, int lock)
 665 {
 666         unsigned int i;
 667
 668         for (i = 0; i < dev->num_tx_queues; i++) {
 669                 struct netdev_queue *dev_queue;
 670                 int val;
 671
 672                 dev_queue = netdev_get_tx_queue(dev, i);
 673
 674                 if (lock)
 675                         spin_lock_bh(&dev_queue->lock);
 676
 677                 val = test_bit(__QUEUE_STATE_QDISC_RUNNING, &dev_queue->state);
 678
 679                 if (lock)
 680                         spin_unlock_bh(&dev_queue->lock);
 681
 682                 if (val)
 683                         return true;
 684         }
 685         return false;
 686 }
 687
 688 void dev_deactivate(struct net_device *dev)
 689 {
 690         bool running;
 691
 692         netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
 693
 694         dev_watchdog_down(dev);
 695
 696         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
 697         synchronize_rcu();
 698
 699         /* Wait for outstanding qdisc_run calls. */
 700         do {
 701                 while (some_qdisc_is_running(dev, 0))
 702                         yield();
 703
 704                 /*
 705                  * Double-check inside queue lock to ensure that all effects
 706                  * of the queue run are visible when we return.
 707                  */
 708                 running = some_qdisc_is_running(dev, 1);
 709
 710                 /*
 711                  * The running flag should never be set at this point because
 712                  * we've already set dev->qdisc to noop_qdisc *inside* the same
 713                  * pair of spin locks.  That is, if any qdisc_run starts after
 714                  * our initial test it should see the noop_qdisc and then
 715                  * clear the RUNNING bit before dropping the queue lock.  So
 716                  * if it is set here then we've found a bug.
 717                  */
 718         } while (WARN_ON_ONCE(running));
 719 }
 720
 721 static void dev_init_scheduler_queue(struct net_device *dev,
 722                                      struct netdev_queue *dev_queue,
 723                                      void *_qdisc)
 724 {
 725         struct Qdisc *qdisc = _qdisc;
 726
 727         dev_queue->qdisc = qdisc;
 728         dev_queue->qdisc_sleeping = qdisc;
 729         INIT_LIST_HEAD(&dev_queue->qdisc_list);
 730 }
 731
 732 void dev_init_scheduler(struct net_device *dev)
 733 {
 734         qdisc_lock_tree(dev);
 735         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
 736         dev_init_scheduler_queue(dev, &dev->rx_queue, NULL);
 737         qdisc_unlock_tree(dev);
 738
 739         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
 740 }
 741
 742 static void shutdown_scheduler_queue(struct net_device *dev,
 743                                      struct netdev_queue *dev_queue,
 744                                      void *_qdisc_default)
 745 {
 746         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
 747         struct Qdisc *qdisc_default = _qdisc_default;
 748
 749         if (qdisc) {
 750                 dev_queue->qdisc = qdisc_default;
 751                 dev_queue->qdisc_sleeping = qdisc_default;
 752
 753                 qdisc_destroy(qdisc);
 754         }
 755 }
 756
 757 void dev_shutdown(struct net_device *dev)
 758 {
 759         qdisc_lock_tree(dev);
 760         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
 761         shutdown_scheduler_queue(dev, &dev->rx_queue, NULL);
 762         BUG_TRAP(!timer_pending(&dev->watchdog_timer));
 763         qdisc_unlock_tree(dev);
 764 }