]> nv-tegra.nvidia Code Review - linux-2.6.git/blob - net/sched/sch_generic.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg...
[linux-2.6.git] / 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                 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_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_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 void qdisc_destroy(struct Qdisc *qdisc)
522 {
523         const struct Qdisc_ops  *ops = qdisc->ops;
524
525         if (qdisc->flags & TCQ_F_BUILTIN ||
526             !atomic_dec_and_test(&qdisc->refcnt))
527                 return;
528
529 #ifdef CONFIG_NET_SCHED
530         qdisc_list_del(qdisc);
531
532         qdisc_put_stab(qdisc->stab);
533 #endif
534         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
535         if (ops->reset)
536                 ops->reset(qdisc);
537         if (ops->destroy)
538                 ops->destroy(qdisc);
539
540         module_put(ops->owner);
541         dev_put(qdisc_dev(qdisc));
542
543         kfree_skb(qdisc->gso_skb);
544
545         kfree((char *) qdisc - qdisc->padded);
546 }
547 EXPORT_SYMBOL(qdisc_destroy);
548
549 static bool dev_all_qdisc_sleeping_noop(struct net_device *dev)
550 {
551         unsigned int i;
552
553         for (i = 0; i < dev->num_tx_queues; i++) {
554                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
555
556                 if (txq->qdisc_sleeping != &noop_qdisc)
557                         return false;
558         }
559         return true;
560 }
561
562 static void attach_one_default_qdisc(struct net_device *dev,
563                                      struct netdev_queue *dev_queue,
564                                      void *_unused)
565 {
566         struct Qdisc *qdisc;
567
568         if (dev->tx_queue_len) {
569                 qdisc = qdisc_create_dflt(dev, dev_queue,
570                                           &pfifo_fast_ops, TC_H_ROOT);
571                 if (!qdisc) {
572                         printk(KERN_INFO "%s: activation failed\n", dev->name);
573                         return;
574                 }
575         } else {
576                 qdisc =  &noqueue_qdisc;
577         }
578         dev_queue->qdisc_sleeping = qdisc;
579 }
580
581 static void transition_one_qdisc(struct net_device *dev,
582                                  struct netdev_queue *dev_queue,
583                                  void *_need_watchdog)
584 {
585         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
586         int *need_watchdog_p = _need_watchdog;
587
588         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
589                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
590
591         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
592         if (need_watchdog_p && new_qdisc != &noqueue_qdisc)
593                 *need_watchdog_p = 1;
594 }
595
596 void dev_activate(struct net_device *dev)
597 {
598         int need_watchdog;
599
600         /* No queueing discipline is attached to device;
601            create default one i.e. pfifo_fast for devices,
602            which need queueing and noqueue_qdisc for
603            virtual interfaces
604          */
605
606         if (dev_all_qdisc_sleeping_noop(dev))
607                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
608
609         if (!netif_carrier_ok(dev))
610                 /* Delay activation until next carrier-on event */
611                 return;
612
613         need_watchdog = 0;
614         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
615         transition_one_qdisc(dev, &dev->rx_queue, NULL);
616
617         if (need_watchdog) {
618                 dev->trans_start = jiffies;
619                 dev_watchdog_up(dev);
620         }
621 }
622
623 static void dev_deactivate_queue(struct net_device *dev,
624                                  struct netdev_queue *dev_queue,
625                                  void *_qdisc_default)
626 {
627         struct Qdisc *qdisc_default = _qdisc_default;
628         struct Qdisc *qdisc;
629
630         qdisc = dev_queue->qdisc;
631         if (qdisc) {
632                 spin_lock_bh(qdisc_lock(qdisc));
633
634                 if (!(qdisc->flags & TCQ_F_BUILTIN))
635                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
636
637                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
638                 qdisc_reset(qdisc);
639
640                 spin_unlock_bh(qdisc_lock(qdisc));
641         }
642 }
643
644 static bool some_qdisc_is_busy(struct net_device *dev)
645 {
646         unsigned int i;
647
648         for (i = 0; i < dev->num_tx_queues; i++) {
649                 struct netdev_queue *dev_queue;
650                 spinlock_t *root_lock;
651                 struct Qdisc *q;
652                 int val;
653
654                 dev_queue = netdev_get_tx_queue(dev, i);
655                 q = dev_queue->qdisc_sleeping;
656                 root_lock = qdisc_lock(q);
657
658                 spin_lock_bh(root_lock);
659
660                 val = (test_bit(__QDISC_STATE_RUNNING, &q->state) ||
661                        test_bit(__QDISC_STATE_SCHED, &q->state));
662
663                 spin_unlock_bh(root_lock);
664
665                 if (val)
666                         return true;
667         }
668         return false;
669 }
670
671 void dev_deactivate(struct net_device *dev)
672 {
673         netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
674         dev_deactivate_queue(dev, &dev->rx_queue, &noop_qdisc);
675
676         dev_watchdog_down(dev);
677
678         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
679         synchronize_rcu();
680
681         /* Wait for outstanding qdisc_run calls. */
682         while (some_qdisc_is_busy(dev))
683                 yield();
684 }
685
686 static void dev_init_scheduler_queue(struct net_device *dev,
687                                      struct netdev_queue *dev_queue,
688                                      void *_qdisc)
689 {
690         struct Qdisc *qdisc = _qdisc;
691
692         dev_queue->qdisc = qdisc;
693         dev_queue->qdisc_sleeping = qdisc;
694 }
695
696 void dev_init_scheduler(struct net_device *dev)
697 {
698         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
699         dev_init_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
700
701         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
702 }
703
704 static void shutdown_scheduler_queue(struct net_device *dev,
705                                      struct netdev_queue *dev_queue,
706                                      void *_qdisc_default)
707 {
708         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
709         struct Qdisc *qdisc_default = _qdisc_default;
710
711         if (qdisc) {
712                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
713                 dev_queue->qdisc_sleeping = qdisc_default;
714
715                 qdisc_destroy(qdisc);
716         }
717 }
718
719 void dev_shutdown(struct net_device *dev)
720 {
721         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
722         shutdown_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
723         WARN_ON(timer_pending(&dev->watchdog_timer));
724 }