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