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