1192da2298358c9189cd37272f2ed32bf376c12a
[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         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         .peek           =       noop_dequeue,
324         .requeue        =       noop_requeue,
325         .owner          =       THIS_MODULE,
326 };
327
328 static struct netdev_queue noop_netdev_queue = {
329         .qdisc          =       &noop_qdisc,
330         .qdisc_sleeping =       &noop_qdisc,
331 };
332
333 struct Qdisc noop_qdisc = {
334         .enqueue        =       noop_enqueue,
335         .dequeue        =       noop_dequeue,
336         .flags          =       TCQ_F_BUILTIN,
337         .ops            =       &noop_qdisc_ops,
338         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
339         .requeue.lock   =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
340         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
341         .dev_queue      =       &noop_netdev_queue,
342 };
343 EXPORT_SYMBOL(noop_qdisc);
344
345 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
346         .id             =       "noqueue",
347         .priv_size      =       0,
348         .enqueue        =       noop_enqueue,
349         .dequeue        =       noop_dequeue,
350         .peek           =       noop_dequeue,
351         .requeue        =       noop_requeue,
352         .owner          =       THIS_MODULE,
353 };
354
355 static struct Qdisc noqueue_qdisc;
356 static struct netdev_queue noqueue_netdev_queue = {
357         .qdisc          =       &noqueue_qdisc,
358         .qdisc_sleeping =       &noqueue_qdisc,
359 };
360
361 static struct Qdisc noqueue_qdisc = {
362         .enqueue        =       NULL,
363         .dequeue        =       noop_dequeue,
364         .flags          =       TCQ_F_BUILTIN,
365         .ops            =       &noqueue_qdisc_ops,
366         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
367         .requeue.lock   =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
368         .q.lock         =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
369         .dev_queue      =       &noqueue_netdev_queue,
370 };
371
372
373 static const u8 prio2band[TC_PRIO_MAX+1] =
374         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
375
376 /* 3-band FIFO queue: old style, but should be a bit faster than
377    generic prio+fifo combination.
378  */
379
380 #define PFIFO_FAST_BANDS 3
381
382 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
383                                              struct Qdisc *qdisc)
384 {
385         struct sk_buff_head *list = qdisc_priv(qdisc);
386         return list + prio2band[skb->priority & TC_PRIO_MAX];
387 }
388
389 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
390 {
391         struct sk_buff_head *list = prio2list(skb, qdisc);
392
393         if (skb_queue_len(list) < qdisc_dev(qdisc)->tx_queue_len) {
394                 qdisc->q.qlen++;
395                 return __qdisc_enqueue_tail(skb, qdisc, list);
396         }
397
398         return qdisc_drop(skb, qdisc);
399 }
400
401 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
402 {
403         int prio;
404         struct sk_buff_head *list = qdisc_priv(qdisc);
405
406         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
407                 if (!skb_queue_empty(list + prio)) {
408                         qdisc->q.qlen--;
409                         return __qdisc_dequeue_head(qdisc, list + prio);
410                 }
411         }
412
413         return NULL;
414 }
415
416 static struct sk_buff *pfifo_fast_peek(struct Qdisc* qdisc)
417 {
418         int prio;
419         struct sk_buff_head *list = qdisc_priv(qdisc);
420
421         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
422                 if (!skb_queue_empty(list + prio))
423                         return skb_peek(list + prio);
424         }
425
426         return NULL;
427 }
428
429 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
430 {
431         qdisc->q.qlen++;
432         return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
433 }
434
435 static void pfifo_fast_reset(struct Qdisc* qdisc)
436 {
437         int prio;
438         struct sk_buff_head *list = qdisc_priv(qdisc);
439
440         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
441                 __qdisc_reset_queue(qdisc, list + prio);
442
443         qdisc->qstats.backlog = 0;
444         qdisc->q.qlen = 0;
445 }
446
447 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
448 {
449         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
450
451         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
452         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
453         return skb->len;
454
455 nla_put_failure:
456         return -1;
457 }
458
459 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
460 {
461         int prio;
462         struct sk_buff_head *list = qdisc_priv(qdisc);
463
464         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
465                 skb_queue_head_init(list + prio);
466
467         return 0;
468 }
469
470 static struct Qdisc_ops pfifo_fast_ops __read_mostly = {
471         .id             =       "pfifo_fast",
472         .priv_size      =       PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
473         .enqueue        =       pfifo_fast_enqueue,
474         .dequeue        =       pfifo_fast_dequeue,
475         .peek           =       pfifo_fast_peek,
476         .requeue        =       pfifo_fast_requeue,
477         .init           =       pfifo_fast_init,
478         .reset          =       pfifo_fast_reset,
479         .dump           =       pfifo_fast_dump,
480         .owner          =       THIS_MODULE,
481 };
482
483 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
484                           struct Qdisc_ops *ops)
485 {
486         void *p;
487         struct Qdisc *sch;
488         unsigned int size;
489         int err = -ENOBUFS;
490
491         /* ensure that the Qdisc and the private data are 32-byte aligned */
492         size = QDISC_ALIGN(sizeof(*sch));
493         size += ops->priv_size + (QDISC_ALIGNTO - 1);
494
495         p = kzalloc(size, GFP_KERNEL);
496         if (!p)
497                 goto errout;
498         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
499         sch->padded = (char *) sch - (char *) p;
500
501         INIT_LIST_HEAD(&sch->list);
502         skb_queue_head_init(&sch->requeue);
503         skb_queue_head_init(&sch->q);
504         sch->ops = ops;
505         sch->enqueue = ops->enqueue;
506         sch->dequeue = ops->dequeue;
507         sch->dev_queue = dev_queue;
508         dev_hold(qdisc_dev(sch));
509         atomic_set(&sch->refcnt, 1);
510
511         return sch;
512 errout:
513         return ERR_PTR(err);
514 }
515
516 struct Qdisc * qdisc_create_dflt(struct net_device *dev,
517                                  struct netdev_queue *dev_queue,
518                                  struct Qdisc_ops *ops,
519                                  unsigned int parentid)
520 {
521         struct Qdisc *sch;
522
523         sch = qdisc_alloc(dev_queue, ops);
524         if (IS_ERR(sch))
525                 goto errout;
526         sch->parent = parentid;
527
528         if (!ops->init || ops->init(sch, NULL) == 0)
529                 return sch;
530
531         qdisc_destroy(sch);
532 errout:
533         return NULL;
534 }
535 EXPORT_SYMBOL(qdisc_create_dflt);
536
537 /* Under qdisc_lock(qdisc) and BH! */
538
539 void qdisc_reset(struct Qdisc *qdisc)
540 {
541         const struct Qdisc_ops *ops = qdisc->ops;
542
543         if (ops->reset)
544                 ops->reset(qdisc);
545
546         kfree_skb(qdisc->gso_skb);
547         qdisc->gso_skb = NULL;
548 }
549 EXPORT_SYMBOL(qdisc_reset);
550
551 void qdisc_destroy(struct Qdisc *qdisc)
552 {
553         const struct Qdisc_ops  *ops = qdisc->ops;
554
555         if (qdisc->flags & TCQ_F_BUILTIN ||
556             !atomic_dec_and_test(&qdisc->refcnt))
557                 return;
558
559 #ifdef CONFIG_NET_SCHED
560         qdisc_list_del(qdisc);
561
562         qdisc_put_stab(qdisc->stab);
563 #endif
564         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
565         if (ops->reset)
566                 ops->reset(qdisc);
567         if (ops->destroy)
568                 ops->destroy(qdisc);
569
570         module_put(ops->owner);
571         dev_put(qdisc_dev(qdisc));
572
573         kfree_skb(qdisc->gso_skb);
574         __skb_queue_purge(&qdisc->requeue);
575
576         kfree((char *) qdisc - qdisc->padded);
577 }
578 EXPORT_SYMBOL(qdisc_destroy);
579
580 static bool dev_all_qdisc_sleeping_noop(struct net_device *dev)
581 {
582         unsigned int i;
583
584         for (i = 0; i < dev->num_tx_queues; i++) {
585                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
586
587                 if (txq->qdisc_sleeping != &noop_qdisc)
588                         return false;
589         }
590         return true;
591 }
592
593 static void attach_one_default_qdisc(struct net_device *dev,
594                                      struct netdev_queue *dev_queue,
595                                      void *_unused)
596 {
597         struct Qdisc *qdisc;
598
599         if (dev->tx_queue_len) {
600                 qdisc = qdisc_create_dflt(dev, dev_queue,
601                                           &pfifo_fast_ops, TC_H_ROOT);
602                 if (!qdisc) {
603                         printk(KERN_INFO "%s: activation failed\n", dev->name);
604                         return;
605                 }
606         } else {
607                 qdisc =  &noqueue_qdisc;
608         }
609         dev_queue->qdisc_sleeping = qdisc;
610 }
611
612 static void transition_one_qdisc(struct net_device *dev,
613                                  struct netdev_queue *dev_queue,
614                                  void *_need_watchdog)
615 {
616         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
617         int *need_watchdog_p = _need_watchdog;
618
619         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
620                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
621
622         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
623         if (need_watchdog_p && new_qdisc != &noqueue_qdisc)
624                 *need_watchdog_p = 1;
625 }
626
627 void dev_activate(struct net_device *dev)
628 {
629         int need_watchdog;
630
631         /* No queueing discipline is attached to device;
632            create default one i.e. pfifo_fast for devices,
633            which need queueing and noqueue_qdisc for
634            virtual interfaces
635          */
636
637         if (dev_all_qdisc_sleeping_noop(dev))
638                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
639
640         if (!netif_carrier_ok(dev))
641                 /* Delay activation until next carrier-on event */
642                 return;
643
644         need_watchdog = 0;
645         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
646         transition_one_qdisc(dev, &dev->rx_queue, NULL);
647
648         if (need_watchdog) {
649                 dev->trans_start = jiffies;
650                 dev_watchdog_up(dev);
651         }
652 }
653
654 static void dev_deactivate_queue(struct net_device *dev,
655                                  struct netdev_queue *dev_queue,
656                                  void *_qdisc_default)
657 {
658         struct Qdisc *qdisc_default = _qdisc_default;
659         struct Qdisc *qdisc;
660
661         qdisc = dev_queue->qdisc;
662         if (qdisc) {
663                 spin_lock_bh(qdisc_lock(qdisc));
664
665                 if (!(qdisc->flags & TCQ_F_BUILTIN))
666                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
667
668                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
669                 qdisc_reset(qdisc);
670
671                 spin_unlock_bh(qdisc_lock(qdisc));
672         }
673 }
674
675 static bool some_qdisc_is_busy(struct net_device *dev)
676 {
677         unsigned int i;
678
679         for (i = 0; i < dev->num_tx_queues; i++) {
680                 struct netdev_queue *dev_queue;
681                 spinlock_t *root_lock;
682                 struct Qdisc *q;
683                 int val;
684
685                 dev_queue = netdev_get_tx_queue(dev, i);
686                 q = dev_queue->qdisc_sleeping;
687                 root_lock = qdisc_lock(q);
688
689                 spin_lock_bh(root_lock);
690
691                 val = (test_bit(__QDISC_STATE_RUNNING, &q->state) ||
692                        test_bit(__QDISC_STATE_SCHED, &q->state));
693
694                 spin_unlock_bh(root_lock);
695
696                 if (val)
697                         return true;
698         }
699         return false;
700 }
701
702 void dev_deactivate(struct net_device *dev)
703 {
704         netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
705         dev_deactivate_queue(dev, &dev->rx_queue, &noop_qdisc);
706
707         dev_watchdog_down(dev);
708
709         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
710         synchronize_rcu();
711
712         /* Wait for outstanding qdisc_run calls. */
713         while (some_qdisc_is_busy(dev))
714                 yield();
715 }
716
717 static void dev_init_scheduler_queue(struct net_device *dev,
718                                      struct netdev_queue *dev_queue,
719                                      void *_qdisc)
720 {
721         struct Qdisc *qdisc = _qdisc;
722
723         dev_queue->qdisc = qdisc;
724         dev_queue->qdisc_sleeping = qdisc;
725 }
726
727 void dev_init_scheduler(struct net_device *dev)
728 {
729         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
730         dev_init_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
731
732         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
733 }
734
735 static void shutdown_scheduler_queue(struct net_device *dev,
736                                      struct netdev_queue *dev_queue,
737                                      void *_qdisc_default)
738 {
739         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
740         struct Qdisc *qdisc_default = _qdisc_default;
741
742         if (qdisc) {
743                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
744                 dev_queue->qdisc_sleeping = qdisc_default;
745
746                 qdisc_destroy(qdisc);
747         }
748 }
749
750 void dev_shutdown(struct net_device *dev)
751 {
752         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
753         shutdown_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
754         WARN_ON(timer_pending(&dev->watchdog_timer));
755 }