ac208c2b2d107d69c02e8571fe1e65483038669d
[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  * queue->lock spinlock.
33  *
34  * The idea is the following:
35  * - enqueue, dequeue are serialized via top level device
36  *   spinlock queue->lock.
37  * - ingress filtering is serialized via top level device
38  *   spinlock dev->rx_queue.lock.
39  * - updates to tree and tree walking are only done under the rtnl mutex.
40  */
41
42 void qdisc_lock_tree(struct net_device *dev)
43         __acquires(dev->rx_queue.lock)
44 {
45         unsigned int i;
46
47         local_bh_disable();
48         for (i = 0; i < dev->num_tx_queues; i++) {
49                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
50                 spin_lock(&txq->lock);
51         }
52         spin_lock(&dev->rx_queue.lock);
53 }
54 EXPORT_SYMBOL(qdisc_lock_tree);
55
56 void qdisc_unlock_tree(struct net_device *dev)
57         __releases(dev->rx_queue.lock)
58 {
59         unsigned int i;
60
61         spin_unlock(&dev->rx_queue.lock);
62         for (i = 0; i < dev->num_tx_queues; i++) {
63                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
64                 spin_unlock(&txq->lock);
65         }
66         local_bh_enable();
67 }
68 EXPORT_SYMBOL(qdisc_unlock_tree);
69
70 static inline int qdisc_qlen(struct Qdisc *q)
71 {
72         return q->q.qlen;
73 }
74
75 static inline int dev_requeue_skb(struct sk_buff *skb,
76                                   struct netdev_queue *dev_queue,
77                                   struct Qdisc *q)
78 {
79         if (unlikely(skb->next))
80                 q->gso_skb = skb;
81         else
82                 q->ops->requeue(skb, q);
83
84         netif_schedule_queue(dev_queue);
85         return 0;
86 }
87
88 static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
89 {
90         struct sk_buff *skb;
91
92         if ((skb = q->gso_skb))
93                 q->gso_skb = NULL;
94         else
95                 skb = q->dequeue(q);
96
97         return skb;
98 }
99
100 static inline int handle_dev_cpu_collision(struct sk_buff *skb,
101                                            struct netdev_queue *dev_queue,
102                                            struct Qdisc *q)
103 {
104         int ret;
105
106         if (unlikely(dev_queue->xmit_lock_owner == smp_processor_id())) {
107                 /*
108                  * Same CPU holding the lock. It may be a transient
109                  * configuration error, when hard_start_xmit() recurses. We
110                  * detect it by checking xmit owner and drop the packet when
111                  * deadloop is detected. Return OK to try the next skb.
112                  */
113                 kfree_skb(skb);
114                 if (net_ratelimit())
115                         printk(KERN_WARNING "Dead loop on netdevice %s, "
116                                "fix it urgently!\n", dev_queue->dev->name);
117                 ret = qdisc_qlen(q);
118         } else {
119                 /*
120                  * Another cpu is holding lock, requeue & delay xmits for
121                  * some time.
122                  */
123                 __get_cpu_var(netdev_rx_stat).cpu_collision++;
124                 ret = dev_requeue_skb(skb, dev_queue, q);
125         }
126
127         return ret;
128 }
129
130 /*
131  * NOTE: Called under queue->lock with locally disabled BH.
132  *
133  * __QDISC_STATE_RUNNING guarantees only one CPU can process
134  * this qdisc at a time. queue->lock serializes queue accesses for
135  * this queue AND txq->qdisc pointer itself.
136  *
137  *  netif_tx_lock serializes accesses to device driver.
138  *
139  *  queue->lock and netif_tx_lock are mutually exclusive,
140  *  if one is grabbed, another must be free.
141  *
142  * Note, that this procedure can be called by a watchdog timer
143  *
144  * Returns to the caller:
145  *                              0  - queue is empty or throttled.
146  *                              >0 - queue is not empty.
147  *
148  */
149 static inline int qdisc_restart(struct netdev_queue *txq,
150                                 struct Qdisc *q)
151 {
152         int ret = NETDEV_TX_BUSY;
153         struct net_device *dev;
154         struct sk_buff *skb;
155
156         /* Dequeue packet */
157         if (unlikely((skb = dequeue_skb(q)) == NULL))
158                 return 0;
159
160         /* And release queue */
161         spin_unlock(&txq->lock);
162
163         dev = txq->dev;
164
165         HARD_TX_LOCK(dev, txq, smp_processor_id());
166         if (!netif_subqueue_stopped(dev, skb))
167                 ret = dev_hard_start_xmit(skb, dev, txq);
168         HARD_TX_UNLOCK(dev, txq);
169
170         spin_lock(&txq->lock);
171
172         switch (ret) {
173         case NETDEV_TX_OK:
174                 /* Driver sent out skb successfully */
175                 ret = qdisc_qlen(q);
176                 break;
177
178         case NETDEV_TX_LOCKED:
179                 /* Driver try lock failed */
180                 ret = handle_dev_cpu_collision(skb, txq, q);
181                 break;
182
183         default:
184                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
185                 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
186                         printk(KERN_WARNING "BUG %s code %d qlen %d\n",
187                                dev->name, ret, q->q.qlen);
188
189                 ret = dev_requeue_skb(skb, txq, q);
190                 break;
191         }
192
193         return ret;
194 }
195
196 void __qdisc_run(struct netdev_queue *txq)
197 {
198         unsigned long start_time = jiffies;
199         struct Qdisc *q = txq->qdisc;
200
201         while (qdisc_restart(txq, q)) {
202                 if (netif_tx_queue_stopped(txq))
203                         break;
204
205                 /*
206                  * Postpone processing if
207                  * 1. another process needs the CPU;
208                  * 2. we've been doing it for too long.
209                  */
210                 if (need_resched() || jiffies != start_time) {
211                         netif_schedule_queue(txq);
212                         break;
213                 }
214         }
215
216         clear_bit(__QDISC_STATE_RUNNING, &q->state);
217 }
218
219 static void dev_watchdog(unsigned long arg)
220 {
221         struct net_device *dev = (struct net_device *)arg;
222
223         netif_tx_lock(dev);
224         if (!qdisc_tx_is_noop(dev)) {
225                 if (netif_device_present(dev) &&
226                     netif_running(dev) &&
227                     netif_carrier_ok(dev)) {
228                         int some_queue_stopped = 0;
229                         unsigned int i;
230
231                         for (i = 0; i < dev->num_tx_queues; i++) {
232                                 struct netdev_queue *txq;
233
234                                 txq = netdev_get_tx_queue(dev, i);
235                                 if (netif_tx_queue_stopped(txq)) {
236                                         some_queue_stopped = 1;
237                                         break;
238                                 }
239                         }
240
241                         if (some_queue_stopped &&
242                             time_after(jiffies, (dev->trans_start +
243                                                  dev->watchdog_timeo))) {
244                                 printk(KERN_INFO "NETDEV WATCHDOG: %s: "
245                                        "transmit timed out\n",
246                                        dev->name);
247                                 dev->tx_timeout(dev);
248                                 WARN_ON_ONCE(1);
249                         }
250                         if (!mod_timer(&dev->watchdog_timer,
251                                        round_jiffies(jiffies +
252                                                      dev->watchdog_timeo)))
253                                 dev_hold(dev);
254                 }
255         }
256         netif_tx_unlock(dev);
257
258         dev_put(dev);
259 }
260
261 void __netdev_watchdog_up(struct net_device *dev)
262 {
263         if (dev->tx_timeout) {
264                 if (dev->watchdog_timeo <= 0)
265                         dev->watchdog_timeo = 5*HZ;
266                 if (!mod_timer(&dev->watchdog_timer,
267                                round_jiffies(jiffies + dev->watchdog_timeo)))
268                         dev_hold(dev);
269         }
270 }
271
272 static void dev_watchdog_up(struct net_device *dev)
273 {
274         __netdev_watchdog_up(dev);
275 }
276
277 static void dev_watchdog_down(struct net_device *dev)
278 {
279         netif_tx_lock_bh(dev);
280         if (del_timer(&dev->watchdog_timer))
281                 dev_put(dev);
282         netif_tx_unlock_bh(dev);
283 }
284
285 /**
286  *      netif_carrier_on - set carrier
287  *      @dev: network device
288  *
289  * Device has detected that carrier.
290  */
291 void netif_carrier_on(struct net_device *dev)
292 {
293         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
294                 linkwatch_fire_event(dev);
295                 if (netif_running(dev))
296                         __netdev_watchdog_up(dev);
297         }
298 }
299 EXPORT_SYMBOL(netif_carrier_on);
300
301 /**
302  *      netif_carrier_off - clear carrier
303  *      @dev: network device
304  *
305  * Device has detected loss of carrier.
306  */
307 void netif_carrier_off(struct net_device *dev)
308 {
309         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state))
310                 linkwatch_fire_event(dev);
311 }
312 EXPORT_SYMBOL(netif_carrier_off);
313
314 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
315    under all circumstances. It is difficult to invent anything faster or
316    cheaper.
317  */
318
319 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
320 {
321         kfree_skb(skb);
322         return NET_XMIT_CN;
323 }
324
325 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
326 {
327         return NULL;
328 }
329
330 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
331 {
332         if (net_ratelimit())
333                 printk(KERN_DEBUG "%s deferred output. It is buggy.\n",
334                        skb->dev->name);
335         kfree_skb(skb);
336         return NET_XMIT_CN;
337 }
338
339 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
340         .id             =       "noop",
341         .priv_size      =       0,
342         .enqueue        =       noop_enqueue,
343         .dequeue        =       noop_dequeue,
344         .requeue        =       noop_requeue,
345         .owner          =       THIS_MODULE,
346 };
347
348 struct Qdisc noop_qdisc = {
349         .enqueue        =       noop_enqueue,
350         .dequeue        =       noop_dequeue,
351         .flags          =       TCQ_F_BUILTIN,
352         .ops            =       &noop_qdisc_ops,
353         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
354 };
355 EXPORT_SYMBOL(noop_qdisc);
356
357 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
358         .id             =       "noqueue",
359         .priv_size      =       0,
360         .enqueue        =       noop_enqueue,
361         .dequeue        =       noop_dequeue,
362         .requeue        =       noop_requeue,
363         .owner          =       THIS_MODULE,
364 };
365
366 static struct Qdisc noqueue_qdisc = {
367         .enqueue        =       NULL,
368         .dequeue        =       noop_dequeue,
369         .flags          =       TCQ_F_BUILTIN,
370         .ops            =       &noqueue_qdisc_ops,
371         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
372 };
373
374
375 static const u8 prio2band[TC_PRIO_MAX+1] =
376         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
377
378 /* 3-band FIFO queue: old style, but should be a bit faster than
379    generic prio+fifo combination.
380  */
381
382 #define PFIFO_FAST_BANDS 3
383
384 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
385                                              struct Qdisc *qdisc)
386 {
387         struct sk_buff_head *list = qdisc_priv(qdisc);
388         return list + prio2band[skb->priority & TC_PRIO_MAX];
389 }
390
391 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
392 {
393         struct sk_buff_head *list = prio2list(skb, qdisc);
394
395         if (skb_queue_len(list) < qdisc_dev(qdisc)->tx_queue_len) {
396                 qdisc->q.qlen++;
397                 return __qdisc_enqueue_tail(skb, qdisc, list);
398         }
399
400         return qdisc_drop(skb, qdisc);
401 }
402
403 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
404 {
405         int prio;
406         struct sk_buff_head *list = qdisc_priv(qdisc);
407
408         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
409                 if (!skb_queue_empty(list + prio)) {
410                         qdisc->q.qlen--;
411                         return __qdisc_dequeue_head(qdisc, list + prio);
412                 }
413         }
414
415         return NULL;
416 }
417
418 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
419 {
420         qdisc->q.qlen++;
421         return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
422 }
423
424 static void pfifo_fast_reset(struct Qdisc* qdisc)
425 {
426         int prio;
427         struct sk_buff_head *list = qdisc_priv(qdisc);
428
429         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
430                 __qdisc_reset_queue(qdisc, list + prio);
431
432         qdisc->qstats.backlog = 0;
433         qdisc->q.qlen = 0;
434 }
435
436 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
437 {
438         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
439
440         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
441         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
442         return skb->len;
443
444 nla_put_failure:
445         return -1;
446 }
447
448 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
449 {
450         int prio;
451         struct sk_buff_head *list = qdisc_priv(qdisc);
452
453         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
454                 skb_queue_head_init(list + prio);
455
456         return 0;
457 }
458
459 static struct Qdisc_ops pfifo_fast_ops __read_mostly = {
460         .id             =       "pfifo_fast",
461         .priv_size      =       PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
462         .enqueue        =       pfifo_fast_enqueue,
463         .dequeue        =       pfifo_fast_dequeue,
464         .requeue        =       pfifo_fast_requeue,
465         .init           =       pfifo_fast_init,
466         .reset          =       pfifo_fast_reset,
467         .dump           =       pfifo_fast_dump,
468         .owner          =       THIS_MODULE,
469 };
470
471 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
472                           struct Qdisc_ops *ops)
473 {
474         void *p;
475         struct Qdisc *sch;
476         unsigned int size;
477         int err = -ENOBUFS;
478
479         /* ensure that the Qdisc and the private data are 32-byte aligned */
480         size = QDISC_ALIGN(sizeof(*sch));
481         size += ops->priv_size + (QDISC_ALIGNTO - 1);
482
483         p = kzalloc(size, GFP_KERNEL);
484         if (!p)
485                 goto errout;
486         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
487         sch->padded = (char *) sch - (char *) p;
488
489         INIT_LIST_HEAD(&sch->list);
490         skb_queue_head_init(&sch->q);
491         sch->ops = ops;
492         sch->enqueue = ops->enqueue;
493         sch->dequeue = ops->dequeue;
494         sch->dev_queue = dev_queue;
495         dev_hold(qdisc_dev(sch));
496         atomic_set(&sch->refcnt, 1);
497
498         return sch;
499 errout:
500         return ERR_PTR(err);
501 }
502
503 struct Qdisc * qdisc_create_dflt(struct net_device *dev,
504                                  struct netdev_queue *dev_queue,
505                                  struct Qdisc_ops *ops,
506                                  unsigned int parentid)
507 {
508         struct Qdisc *sch;
509
510         sch = qdisc_alloc(dev_queue, ops);
511         if (IS_ERR(sch))
512                 goto errout;
513         sch->parent = parentid;
514
515         if (!ops->init || ops->init(sch, NULL) == 0)
516                 return sch;
517
518         qdisc_destroy(sch);
519 errout:
520         return NULL;
521 }
522 EXPORT_SYMBOL(qdisc_create_dflt);
523
524 /* Under queue->lock and BH! */
525
526 void qdisc_reset(struct Qdisc *qdisc)
527 {
528         const struct Qdisc_ops *ops = qdisc->ops;
529
530         if (ops->reset)
531                 ops->reset(qdisc);
532 }
533 EXPORT_SYMBOL(qdisc_reset);
534
535 /* this is the rcu callback function to clean up a qdisc when there
536  * are no further references to it */
537
538 static void __qdisc_destroy(struct rcu_head *head)
539 {
540         struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu);
541         kfree((char *) qdisc - qdisc->padded);
542 }
543
544 /* Under queue->lock and BH! */
545
546 void qdisc_destroy(struct Qdisc *qdisc)
547 {
548         const struct Qdisc_ops  *ops = qdisc->ops;
549
550         if (qdisc->flags & TCQ_F_BUILTIN ||
551             !atomic_dec_and_test(&qdisc->refcnt))
552                 return;
553
554         list_del(&qdisc->list);
555         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
556         if (ops->reset)
557                 ops->reset(qdisc);
558         if (ops->destroy)
559                 ops->destroy(qdisc);
560
561         module_put(ops->owner);
562         dev_put(qdisc_dev(qdisc));
563         call_rcu(&qdisc->q_rcu, __qdisc_destroy);
564 }
565 EXPORT_SYMBOL(qdisc_destroy);
566
567 static bool dev_all_qdisc_sleeping_noop(struct net_device *dev)
568 {
569         unsigned int i;
570
571         for (i = 0; i < dev->num_tx_queues; i++) {
572                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
573
574                 if (txq->qdisc_sleeping != &noop_qdisc)
575                         return false;
576         }
577         return true;
578 }
579
580 static void attach_one_default_qdisc(struct net_device *dev,
581                                      struct netdev_queue *dev_queue,
582                                      void *_unused)
583 {
584         struct Qdisc *qdisc;
585
586         if (dev->tx_queue_len) {
587                 qdisc = qdisc_create_dflt(dev, dev_queue,
588                                           &pfifo_fast_ops, TC_H_ROOT);
589                 if (!qdisc) {
590                         printk(KERN_INFO "%s: activation failed\n", dev->name);
591                         return;
592                 }
593                 list_add_tail(&qdisc->list, &dev_queue->qdisc_list);
594         } else {
595                 qdisc =  &noqueue_qdisc;
596         }
597         dev_queue->qdisc_sleeping = qdisc;
598 }
599
600 static void transition_one_qdisc(struct net_device *dev,
601                                  struct netdev_queue *dev_queue,
602                                  void *_need_watchdog)
603 {
604         int *need_watchdog_p = _need_watchdog;
605
606         spin_lock_bh(&dev_queue->lock);
607         rcu_assign_pointer(dev_queue->qdisc, dev_queue->qdisc_sleeping);
608         if (dev_queue->qdisc != &noqueue_qdisc)
609                 *need_watchdog_p = 1;
610         spin_unlock_bh(&dev_queue->lock);
611 }
612
613 void dev_activate(struct net_device *dev)
614 {
615         int need_watchdog;
616
617         /* No queueing discipline is attached to device;
618            create default one i.e. pfifo_fast for devices,
619            which need queueing and noqueue_qdisc for
620            virtual interfaces
621          */
622
623         if (dev_all_qdisc_sleeping_noop(dev))
624                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
625
626         if (!netif_carrier_ok(dev))
627                 /* Delay activation until next carrier-on event */
628                 return;
629
630         need_watchdog = 0;
631         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
632
633         if (need_watchdog) {
634                 dev->trans_start = jiffies;
635                 dev_watchdog_up(dev);
636         }
637 }
638
639 static void dev_deactivate_queue(struct net_device *dev,
640                                  struct netdev_queue *dev_queue,
641                                  void *_qdisc_default)
642 {
643         struct Qdisc *qdisc_default = _qdisc_default;
644         struct sk_buff *skb = NULL;
645         struct Qdisc *qdisc;
646
647         spin_lock_bh(&dev_queue->lock);
648
649         qdisc = dev_queue->qdisc;
650         if (qdisc) {
651                 dev_queue->qdisc = qdisc_default;
652                 qdisc_reset(qdisc);
653
654                 skb = qdisc->gso_skb;
655                 qdisc->gso_skb = NULL;
656         }
657
658         spin_unlock_bh(&dev_queue->lock);
659
660         kfree_skb(skb);
661 }
662
663 static bool some_qdisc_is_running(struct net_device *dev, int lock)
664 {
665         unsigned int i;
666
667         for (i = 0; i < dev->num_tx_queues; i++) {
668                 struct netdev_queue *dev_queue;
669                 struct Qdisc *q;
670                 int val;
671
672                 dev_queue = netdev_get_tx_queue(dev, i);
673                 q = dev_queue->qdisc;
674
675                 if (lock)
676                         spin_lock_bh(&dev_queue->lock);
677
678                 val = test_bit(__QDISC_STATE_RUNNING, &q->state);
679
680                 if (lock)
681                         spin_unlock_bh(&dev_queue->lock);
682
683                 if (val)
684                         return true;
685         }
686         return false;
687 }
688
689 void dev_deactivate(struct net_device *dev)
690 {
691         bool running;
692
693         netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
694
695         dev_watchdog_down(dev);
696
697         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
698         synchronize_rcu();
699
700         /* Wait for outstanding qdisc_run calls. */
701         do {
702                 while (some_qdisc_is_running(dev, 0))
703                         yield();
704
705                 /*
706                  * Double-check inside queue lock to ensure that all effects
707                  * of the queue run are visible when we return.
708                  */
709                 running = some_qdisc_is_running(dev, 1);
710
711                 /*
712                  * The running flag should never be set at this point because
713                  * we've already set dev->qdisc to noop_qdisc *inside* the same
714                  * pair of spin locks.  That is, if any qdisc_run starts after
715                  * our initial test it should see the noop_qdisc and then
716                  * clear the RUNNING bit before dropping the queue lock.  So
717                  * if it is set here then we've found a bug.
718                  */
719         } while (WARN_ON_ONCE(running));
720 }
721
722 static void dev_init_scheduler_queue(struct net_device *dev,
723                                      struct netdev_queue *dev_queue,
724                                      void *_qdisc)
725 {
726         struct Qdisc *qdisc = _qdisc;
727
728         dev_queue->qdisc = qdisc;
729         dev_queue->qdisc_sleeping = qdisc;
730         INIT_LIST_HEAD(&dev_queue->qdisc_list);
731 }
732
733 void dev_init_scheduler(struct net_device *dev)
734 {
735         qdisc_lock_tree(dev);
736         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
737         dev_init_scheduler_queue(dev, &dev->rx_queue, NULL);
738         qdisc_unlock_tree(dev);
739
740         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
741 }
742
743 static void shutdown_scheduler_queue(struct net_device *dev,
744                                      struct netdev_queue *dev_queue,
745                                      void *_qdisc_default)
746 {
747         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
748         struct Qdisc *qdisc_default = _qdisc_default;
749
750         if (qdisc) {
751                 dev_queue->qdisc = qdisc_default;
752                 dev_queue->qdisc_sleeping = qdisc_default;
753
754                 qdisc_destroy(qdisc);
755         }
756 }
757
758 void dev_shutdown(struct net_device *dev)
759 {
760         qdisc_lock_tree(dev);
761         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
762         shutdown_scheduler_queue(dev, &dev->rx_queue, NULL);
763         BUG_TRAP(!timer_pending(&dev->watchdog_timer));
764         qdisc_unlock_tree(dev);
765 }