Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
[linux-3.10.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         q->gso_skb = skb;
48         q->qstats.requeues++;
49         __netif_schedule(q);
50
51         return 0;
52 }
53
54 static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
55 {
56         struct sk_buff *skb = q->gso_skb;
57
58         if (unlikely(skb)) {
59                 struct net_device *dev = qdisc_dev(q);
60                 struct netdev_queue *txq;
61
62                 /* check the reason of requeuing without tx lock first */
63                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
64                 if (!netif_tx_queue_stopped(txq) && !netif_tx_queue_frozen(txq))
65                         q->gso_skb = NULL;
66                 else
67                         skb = NULL;
68         } else {
69                 skb = q->dequeue(q);
70         }
71
72         return skb;
73 }
74
75 static inline int handle_dev_cpu_collision(struct sk_buff *skb,
76                                            struct netdev_queue *dev_queue,
77                                            struct Qdisc *q)
78 {
79         int ret;
80
81         if (unlikely(dev_queue->xmit_lock_owner == smp_processor_id())) {
82                 /*
83                  * Same CPU holding the lock. It may be a transient
84                  * configuration error, when hard_start_xmit() recurses. We
85                  * detect it by checking xmit owner and drop the packet when
86                  * deadloop is detected. Return OK to try the next skb.
87                  */
88                 kfree_skb(skb);
89                 if (net_ratelimit())
90                         printk(KERN_WARNING "Dead loop on netdevice %s, "
91                                "fix it urgently!\n", dev_queue->dev->name);
92                 ret = qdisc_qlen(q);
93         } else {
94                 /*
95                  * Another cpu is holding lock, requeue & delay xmits for
96                  * some time.
97                  */
98                 __get_cpu_var(netdev_rx_stat).cpu_collision++;
99                 ret = dev_requeue_skb(skb, q);
100         }
101
102         return ret;
103 }
104
105 /*
106  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
107  *
108  * __QDISC_STATE_RUNNING guarantees only one CPU can process
109  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
110  * this queue.
111  *
112  *  netif_tx_lock serializes accesses to device driver.
113  *
114  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
115  *  if one is grabbed, another must be free.
116  *
117  * Note, that this procedure can be called by a watchdog timer
118  *
119  * Returns to the caller:
120  *                              0  - queue is empty or throttled.
121  *                              >0 - queue is not empty.
122  *
123  */
124 static inline int qdisc_restart(struct Qdisc *q)
125 {
126         struct netdev_queue *txq;
127         int ret = NETDEV_TX_BUSY;
128         struct net_device *dev;
129         spinlock_t *root_lock;
130         struct sk_buff *skb;
131
132         /* Dequeue packet */
133         if (unlikely((skb = dequeue_skb(q)) == NULL))
134                 return 0;
135
136         root_lock = qdisc_lock(q);
137
138         /* And release qdisc */
139         spin_unlock(root_lock);
140
141         dev = qdisc_dev(q);
142         txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
143
144         HARD_TX_LOCK(dev, txq, smp_processor_id());
145         if (!netif_tx_queue_stopped(txq) &&
146             !netif_tx_queue_frozen(txq))
147                 ret = dev_hard_start_xmit(skb, dev, txq);
148         HARD_TX_UNLOCK(dev, txq);
149
150         spin_lock(root_lock);
151
152         switch (ret) {
153         case NETDEV_TX_OK:
154                 /* Driver sent out skb successfully */
155                 ret = qdisc_qlen(q);
156                 break;
157
158         case NETDEV_TX_LOCKED:
159                 /* Driver try lock failed */
160                 ret = handle_dev_cpu_collision(skb, txq, q);
161                 break;
162
163         default:
164                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
165                 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
166                         printk(KERN_WARNING "BUG %s code %d qlen %d\n",
167                                dev->name, ret, q->q.qlen);
168
169                 ret = dev_requeue_skb(skb, q);
170                 break;
171         }
172
173         if (ret && (netif_tx_queue_stopped(txq) ||
174                     netif_tx_queue_frozen(txq)))
175                 ret = 0;
176
177         return ret;
178 }
179
180 void __qdisc_run(struct Qdisc *q)
181 {
182         unsigned long start_time = jiffies;
183
184         while (qdisc_restart(q)) {
185                 /*
186                  * Postpone processing if
187                  * 1. another process needs the CPU;
188                  * 2. we've been doing it for too long.
189                  */
190                 if (need_resched() || jiffies != start_time) {
191                         __netif_schedule(q);
192                         break;
193                 }
194         }
195
196         clear_bit(__QDISC_STATE_RUNNING, &q->state);
197 }
198
199 static void dev_watchdog(unsigned long arg)
200 {
201         struct net_device *dev = (struct net_device *)arg;
202
203         netif_tx_lock(dev);
204         if (!qdisc_tx_is_noop(dev)) {
205                 if (netif_device_present(dev) &&
206                     netif_running(dev) &&
207                     netif_carrier_ok(dev)) {
208                         int some_queue_stopped = 0;
209                         unsigned int i;
210
211                         for (i = 0; i < dev->num_tx_queues; i++) {
212                                 struct netdev_queue *txq;
213
214                                 txq = netdev_get_tx_queue(dev, i);
215                                 if (netif_tx_queue_stopped(txq)) {
216                                         some_queue_stopped = 1;
217                                         break;
218                                 }
219                         }
220
221                         if (some_queue_stopped &&
222                             time_after(jiffies, (dev->trans_start +
223                                                  dev->watchdog_timeo))) {
224                                 char drivername[64];
225                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit timed out\n",
226                                        dev->name, netdev_drivername(dev, drivername, 64));
227                                 dev->tx_timeout(dev);
228                         }
229                         if (!mod_timer(&dev->watchdog_timer,
230                                        round_jiffies(jiffies +
231                                                      dev->watchdog_timeo)))
232                                 dev_hold(dev);
233                 }
234         }
235         netif_tx_unlock(dev);
236
237         dev_put(dev);
238 }
239
240 void __netdev_watchdog_up(struct net_device *dev)
241 {
242         if (dev->tx_timeout) {
243                 if (dev->watchdog_timeo <= 0)
244                         dev->watchdog_timeo = 5*HZ;
245                 if (!mod_timer(&dev->watchdog_timer,
246                                round_jiffies(jiffies + dev->watchdog_timeo)))
247                         dev_hold(dev);
248         }
249 }
250
251 static void dev_watchdog_up(struct net_device *dev)
252 {
253         __netdev_watchdog_up(dev);
254 }
255
256 static void dev_watchdog_down(struct net_device *dev)
257 {
258         netif_tx_lock_bh(dev);
259         if (del_timer(&dev->watchdog_timer))
260                 dev_put(dev);
261         netif_tx_unlock_bh(dev);
262 }
263
264 /**
265  *      netif_carrier_on - set carrier
266  *      @dev: network device
267  *
268  * Device has detected that carrier.
269  */
270 void netif_carrier_on(struct net_device *dev)
271 {
272         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
273                 linkwatch_fire_event(dev);
274                 if (netif_running(dev))
275                         __netdev_watchdog_up(dev);
276         }
277 }
278 EXPORT_SYMBOL(netif_carrier_on);
279
280 /**
281  *      netif_carrier_off - clear carrier
282  *      @dev: network device
283  *
284  * Device has detected loss of carrier.
285  */
286 void netif_carrier_off(struct net_device *dev)
287 {
288         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state))
289                 linkwatch_fire_event(dev);
290 }
291 EXPORT_SYMBOL(netif_carrier_off);
292
293 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
294    under all circumstances. It is difficult to invent anything faster or
295    cheaper.
296  */
297
298 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
299 {
300         kfree_skb(skb);
301         return NET_XMIT_CN;
302 }
303
304 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
305 {
306         return NULL;
307 }
308
309 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
310 {
311         if (net_ratelimit())
312                 printk(KERN_DEBUG "%s deferred output. It is buggy.\n",
313                        skb->dev->name);
314         kfree_skb(skb);
315         return NET_XMIT_CN;
316 }
317
318 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
319         .id             =       "noop",
320         .priv_size      =       0,
321         .enqueue        =       noop_enqueue,
322         .dequeue        =       noop_dequeue,
323         .requeue        =       noop_requeue,
324         .owner          =       THIS_MODULE,
325 };
326
327 static struct netdev_queue noop_netdev_queue = {
328         .qdisc          =       &noop_qdisc,
329         .qdisc_sleeping =       &noop_qdisc,
330 };
331
332 struct Qdisc noop_qdisc = {
333         .enqueue        =       noop_enqueue,
334         .dequeue        =       noop_dequeue,
335         .flags          =       TCQ_F_BUILTIN,
336         .ops            =       &noop_qdisc_ops,
337         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
338         .requeue.lock   =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
339         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
340         .dev_queue      =       &noop_netdev_queue,
341 };
342 EXPORT_SYMBOL(noop_qdisc);
343
344 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
345         .id             =       "noqueue",
346         .priv_size      =       0,
347         .enqueue        =       noop_enqueue,
348         .dequeue        =       noop_dequeue,
349         .requeue        =       noop_requeue,
350         .owner          =       THIS_MODULE,
351 };
352
353 static struct Qdisc noqueue_qdisc;
354 static struct netdev_queue noqueue_netdev_queue = {
355         .qdisc          =       &noqueue_qdisc,
356         .qdisc_sleeping =       &noqueue_qdisc,
357 };
358
359 static struct Qdisc noqueue_qdisc = {
360         .enqueue        =       NULL,
361         .dequeue        =       noop_dequeue,
362         .flags          =       TCQ_F_BUILTIN,
363         .ops            =       &noqueue_qdisc_ops,
364         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
365         .requeue.lock   =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
366         .q.lock         =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
367         .dev_queue      =       &noqueue_netdev_queue,
368 };
369
370
371 static const u8 prio2band[TC_PRIO_MAX+1] =
372         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
373
374 /* 3-band FIFO queue: old style, but should be a bit faster than
375    generic prio+fifo combination.
376  */
377
378 #define PFIFO_FAST_BANDS 3
379
380 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
381                                              struct Qdisc *qdisc)
382 {
383         struct sk_buff_head *list = qdisc_priv(qdisc);
384         return list + prio2band[skb->priority & TC_PRIO_MAX];
385 }
386
387 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
388 {
389         struct sk_buff_head *list = prio2list(skb, qdisc);
390
391         if (skb_queue_len(list) < qdisc_dev(qdisc)->tx_queue_len) {
392                 qdisc->q.qlen++;
393                 return __qdisc_enqueue_tail(skb, qdisc, list);
394         }
395
396         return qdisc_drop(skb, qdisc);
397 }
398
399 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
400 {
401         int prio;
402         struct sk_buff_head *list = qdisc_priv(qdisc);
403
404         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
405                 if (!skb_queue_empty(list + prio)) {
406                         qdisc->q.qlen--;
407                         return __qdisc_dequeue_head(qdisc, list + prio);
408                 }
409         }
410
411         return NULL;
412 }
413
414 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
415 {
416         qdisc->q.qlen++;
417         return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
418 }
419
420 static void pfifo_fast_reset(struct Qdisc* qdisc)
421 {
422         int prio;
423         struct sk_buff_head *list = qdisc_priv(qdisc);
424
425         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
426                 __qdisc_reset_queue(qdisc, list + prio);
427
428         qdisc->qstats.backlog = 0;
429         qdisc->q.qlen = 0;
430 }
431
432 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
433 {
434         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
435
436         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
437         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
438         return skb->len;
439
440 nla_put_failure:
441         return -1;
442 }
443
444 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
445 {
446         int prio;
447         struct sk_buff_head *list = qdisc_priv(qdisc);
448
449         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
450                 skb_queue_head_init(list + prio);
451
452         return 0;
453 }
454
455 static struct Qdisc_ops pfifo_fast_ops __read_mostly = {
456         .id             =       "pfifo_fast",
457         .priv_size      =       PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
458         .enqueue        =       pfifo_fast_enqueue,
459         .dequeue        =       pfifo_fast_dequeue,
460         .requeue        =       pfifo_fast_requeue,
461         .init           =       pfifo_fast_init,
462         .reset          =       pfifo_fast_reset,
463         .dump           =       pfifo_fast_dump,
464         .owner          =       THIS_MODULE,
465 };
466
467 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
468                           struct Qdisc_ops *ops)
469 {
470         void *p;
471         struct Qdisc *sch;
472         unsigned int size;
473         int err = -ENOBUFS;
474
475         /* ensure that the Qdisc and the private data are 32-byte aligned */
476         size = QDISC_ALIGN(sizeof(*sch));
477         size += ops->priv_size + (QDISC_ALIGNTO - 1);
478
479         p = kzalloc(size, GFP_KERNEL);
480         if (!p)
481                 goto errout;
482         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
483         sch->padded = (char *) sch - (char *) p;
484
485         INIT_LIST_HEAD(&sch->list);
486         skb_queue_head_init(&sch->requeue);
487         skb_queue_head_init(&sch->q);
488         sch->ops = ops;
489         sch->enqueue = ops->enqueue;
490         sch->dequeue = ops->dequeue;
491         sch->dev_queue = dev_queue;
492         dev_hold(qdisc_dev(sch));
493         atomic_set(&sch->refcnt, 1);
494
495         return sch;
496 errout:
497         return ERR_PTR(err);
498 }
499
500 struct Qdisc * qdisc_create_dflt(struct net_device *dev,
501                                  struct netdev_queue *dev_queue,
502                                  struct Qdisc_ops *ops,
503                                  unsigned int parentid)
504 {
505         struct Qdisc *sch;
506
507         sch = qdisc_alloc(dev_queue, ops);
508         if (IS_ERR(sch))
509                 goto errout;
510         sch->parent = parentid;
511
512         if (!ops->init || ops->init(sch, NULL) == 0)
513                 return sch;
514
515         qdisc_destroy(sch);
516 errout:
517         return NULL;
518 }
519 EXPORT_SYMBOL(qdisc_create_dflt);
520
521 /* Under qdisc_lock(qdisc) and BH! */
522
523 void qdisc_reset(struct Qdisc *qdisc)
524 {
525         const struct Qdisc_ops *ops = qdisc->ops;
526
527         if (ops->reset)
528                 ops->reset(qdisc);
529 }
530 EXPORT_SYMBOL(qdisc_reset);
531
532 void qdisc_destroy(struct Qdisc *qdisc)
533 {
534         const struct Qdisc_ops  *ops = qdisc->ops;
535
536         if (qdisc->flags & TCQ_F_BUILTIN ||
537             !atomic_dec_and_test(&qdisc->refcnt))
538                 return;
539
540 #ifdef CONFIG_NET_SCHED
541         qdisc_list_del(qdisc);
542
543         qdisc_put_stab(qdisc->stab);
544 #endif
545         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
546         if (ops->reset)
547                 ops->reset(qdisc);
548         if (ops->destroy)
549                 ops->destroy(qdisc);
550
551         module_put(ops->owner);
552         dev_put(qdisc_dev(qdisc));
553
554         kfree_skb(qdisc->gso_skb);
555         __skb_queue_purge(&qdisc->requeue);
556
557         kfree((char *) qdisc - qdisc->padded);
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         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
601                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
602
603         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
604         if (need_watchdog_p && new_qdisc != &noqueue_qdisc)
605                 *need_watchdog_p = 1;
606 }
607
608 void dev_activate(struct net_device *dev)
609 {
610         int need_watchdog;
611
612         /* No queueing discipline is attached to device;
613            create default one i.e. pfifo_fast for devices,
614            which need queueing and noqueue_qdisc for
615            virtual interfaces
616          */
617
618         if (dev_all_qdisc_sleeping_noop(dev))
619                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
620
621         if (!netif_carrier_ok(dev))
622                 /* Delay activation until next carrier-on event */
623                 return;
624
625         need_watchdog = 0;
626         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
627         transition_one_qdisc(dev, &dev->rx_queue, NULL);
628
629         if (need_watchdog) {
630                 dev->trans_start = jiffies;
631                 dev_watchdog_up(dev);
632         }
633 }
634
635 static void dev_deactivate_queue(struct net_device *dev,
636                                  struct netdev_queue *dev_queue,
637                                  void *_qdisc_default)
638 {
639         struct Qdisc *qdisc_default = _qdisc_default;
640         struct Qdisc *qdisc;
641
642         qdisc = dev_queue->qdisc;
643         if (qdisc) {
644                 spin_lock_bh(qdisc_lock(qdisc));
645
646                 if (!(qdisc->flags & TCQ_F_BUILTIN))
647                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
648
649                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
650                 qdisc_reset(qdisc);
651
652                 spin_unlock_bh(qdisc_lock(qdisc));
653         }
654 }
655
656 static bool some_qdisc_is_busy(struct net_device *dev)
657 {
658         unsigned int i;
659
660         for (i = 0; i < dev->num_tx_queues; i++) {
661                 struct netdev_queue *dev_queue;
662                 spinlock_t *root_lock;
663                 struct Qdisc *q;
664                 int val;
665
666                 dev_queue = netdev_get_tx_queue(dev, i);
667                 q = dev_queue->qdisc_sleeping;
668                 root_lock = qdisc_lock(q);
669
670                 spin_lock_bh(root_lock);
671
672                 val = (test_bit(__QDISC_STATE_RUNNING, &q->state) ||
673                        test_bit(__QDISC_STATE_SCHED, &q->state));
674
675                 spin_unlock_bh(root_lock);
676
677                 if (val)
678                         return true;
679         }
680         return false;
681 }
682
683 void dev_deactivate(struct net_device *dev)
684 {
685         netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
686         dev_deactivate_queue(dev, &dev->rx_queue, &noop_qdisc);
687
688         dev_watchdog_down(dev);
689
690         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
691         synchronize_rcu();
692
693         /* Wait for outstanding qdisc_run calls. */
694         while (some_qdisc_is_busy(dev))
695                 yield();
696 }
697
698 static void dev_init_scheduler_queue(struct net_device *dev,
699                                      struct netdev_queue *dev_queue,
700                                      void *_qdisc)
701 {
702         struct Qdisc *qdisc = _qdisc;
703
704         dev_queue->qdisc = qdisc;
705         dev_queue->qdisc_sleeping = qdisc;
706 }
707
708 void dev_init_scheduler(struct net_device *dev)
709 {
710         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
711         dev_init_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
712
713         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
714 }
715
716 static void shutdown_scheduler_queue(struct net_device *dev,
717                                      struct netdev_queue *dev_queue,
718                                      void *_qdisc_default)
719 {
720         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
721         struct Qdisc *qdisc_default = _qdisc_default;
722
723         if (qdisc) {
724                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
725                 dev_queue->qdisc_sleeping = qdisc_default;
726
727                 qdisc_destroy(qdisc);
728         }
729 }
730
731 void dev_shutdown(struct net_device *dev)
732 {
733         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
734         shutdown_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
735         WARN_ON(timer_pending(&dev->watchdog_timer));
736 }