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