Merge tag 'md/4.0-rc4-fix' of git://neil.brown.name/md
[linux-2.6-microblaze.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 <linux/slab.h>
28 #include <linux/if_vlan.h>
29 #include <net/sch_generic.h>
30 #include <net/pkt_sched.h>
31 #include <net/dst.h>
32
33 /* Qdisc to use by default */
34 const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
35 EXPORT_SYMBOL(default_qdisc_ops);
36
37 /* Main transmission queue. */
38
39 /* Modifications to data participating in scheduling must be protected with
40  * qdisc_lock(qdisc) spinlock.
41  *
42  * The idea is the following:
43  * - enqueue, dequeue are serialized via qdisc root lock
44  * - ingress filtering is also serialized via qdisc root lock
45  * - updates to tree and tree walking are only done under the rtnl mutex.
46  */
47
48 static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
49 {
50         q->gso_skb = skb;
51         q->qstats.requeues++;
52         q->q.qlen++;    /* it's still part of the queue */
53         __netif_schedule(q);
54
55         return 0;
56 }
57
58 static void try_bulk_dequeue_skb(struct Qdisc *q,
59                                  struct sk_buff *skb,
60                                  const struct netdev_queue *txq,
61                                  int *packets)
62 {
63         int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
64
65         while (bytelimit > 0) {
66                 struct sk_buff *nskb = q->dequeue(q);
67
68                 if (!nskb)
69                         break;
70
71                 bytelimit -= nskb->len; /* covers GSO len */
72                 skb->next = nskb;
73                 skb = nskb;
74                 (*packets)++; /* GSO counts as one pkt */
75         }
76         skb->next = NULL;
77 }
78
79 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
80  * A requeued skb (via q->gso_skb) can also be a SKB list.
81  */
82 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
83                                    int *packets)
84 {
85         struct sk_buff *skb = q->gso_skb;
86         const struct netdev_queue *txq = q->dev_queue;
87
88         *packets = 1;
89         *validate = true;
90         if (unlikely(skb)) {
91                 /* check the reason of requeuing without tx lock first */
92                 txq = skb_get_tx_queue(txq->dev, skb);
93                 if (!netif_xmit_frozen_or_stopped(txq)) {
94                         q->gso_skb = NULL;
95                         q->q.qlen--;
96                 } else
97                         skb = NULL;
98                 /* skb in gso_skb were already validated */
99                 *validate = false;
100         } else {
101                 if (!(q->flags & TCQ_F_ONETXQUEUE) ||
102                     !netif_xmit_frozen_or_stopped(txq)) {
103                         skb = q->dequeue(q);
104                         if (skb && qdisc_may_bulk(q))
105                                 try_bulk_dequeue_skb(q, skb, txq, packets);
106                 }
107         }
108         return skb;
109 }
110
111 static inline int handle_dev_cpu_collision(struct sk_buff *skb,
112                                            struct netdev_queue *dev_queue,
113                                            struct Qdisc *q)
114 {
115         int ret;
116
117         if (unlikely(dev_queue->xmit_lock_owner == smp_processor_id())) {
118                 /*
119                  * Same CPU holding the lock. It may be a transient
120                  * configuration error, when hard_start_xmit() recurses. We
121                  * detect it by checking xmit owner and drop the packet when
122                  * deadloop is detected. Return OK to try the next skb.
123                  */
124                 kfree_skb_list(skb);
125                 net_warn_ratelimited("Dead loop on netdevice %s, fix it urgently!\n",
126                                      dev_queue->dev->name);
127                 ret = qdisc_qlen(q);
128         } else {
129                 /*
130                  * Another cpu is holding lock, requeue & delay xmits for
131                  * some time.
132                  */
133                 __this_cpu_inc(softnet_data.cpu_collision);
134                 ret = dev_requeue_skb(skb, q);
135         }
136
137         return ret;
138 }
139
140 /*
141  * Transmit possibly several skbs, and handle the return status as
142  * required. Holding the __QDISC___STATE_RUNNING bit guarantees that
143  * only one CPU can execute this function.
144  *
145  * Returns to the caller:
146  *                              0  - queue is empty or throttled.
147  *                              >0 - queue is not empty.
148  */
149 int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
150                     struct net_device *dev, struct netdev_queue *txq,
151                     spinlock_t *root_lock, bool validate)
152 {
153         int ret = NETDEV_TX_BUSY;
154
155         /* And release qdisc */
156         spin_unlock(root_lock);
157
158         /* Note that we validate skb (GSO, checksum, ...) outside of locks */
159         if (validate)
160                 skb = validate_xmit_skb_list(skb, dev);
161
162         if (skb) {
163                 HARD_TX_LOCK(dev, txq, smp_processor_id());
164                 if (!netif_xmit_frozen_or_stopped(txq))
165                         skb = dev_hard_start_xmit(skb, dev, txq, &ret);
166
167                 HARD_TX_UNLOCK(dev, txq);
168         }
169         spin_lock(root_lock);
170
171         if (dev_xmit_complete(ret)) {
172                 /* Driver sent out skb successfully or skb was consumed */
173                 ret = qdisc_qlen(q);
174         } else if (ret == NETDEV_TX_LOCKED) {
175                 /* Driver try lock failed */
176                 ret = handle_dev_cpu_collision(skb, txq, q);
177         } else {
178                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
179                 if (unlikely(ret != NETDEV_TX_BUSY))
180                         net_warn_ratelimited("BUG %s code %d qlen %d\n",
181                                              dev->name, ret, q->q.qlen);
182
183                 ret = dev_requeue_skb(skb, q);
184         }
185
186         if (ret && netif_xmit_frozen_or_stopped(txq))
187                 ret = 0;
188
189         return ret;
190 }
191
192 /*
193  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
194  *
195  * __QDISC___STATE_RUNNING guarantees only one CPU can process
196  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
197  * this queue.
198  *
199  *  netif_tx_lock serializes accesses to device driver.
200  *
201  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
202  *  if one is grabbed, another must be free.
203  *
204  * Note, that this procedure can be called by a watchdog timer
205  *
206  * Returns to the caller:
207  *                              0  - queue is empty or throttled.
208  *                              >0 - queue is not empty.
209  *
210  */
211 static inline int qdisc_restart(struct Qdisc *q, int *packets)
212 {
213         struct netdev_queue *txq;
214         struct net_device *dev;
215         spinlock_t *root_lock;
216         struct sk_buff *skb;
217         bool validate;
218
219         /* Dequeue packet */
220         skb = dequeue_skb(q, &validate, packets);
221         if (unlikely(!skb))
222                 return 0;
223
224         root_lock = qdisc_lock(q);
225         dev = qdisc_dev(q);
226         txq = skb_get_tx_queue(dev, skb);
227
228         return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
229 }
230
231 void __qdisc_run(struct Qdisc *q)
232 {
233         int quota = weight_p;
234         int packets;
235
236         while (qdisc_restart(q, &packets)) {
237                 /*
238                  * Ordered by possible occurrence: Postpone processing if
239                  * 1. we've exceeded packet quota
240                  * 2. another process needs the CPU;
241                  */
242                 quota -= packets;
243                 if (quota <= 0 || need_resched()) {
244                         __netif_schedule(q);
245                         break;
246                 }
247         }
248
249         qdisc_run_end(q);
250 }
251
252 unsigned long dev_trans_start(struct net_device *dev)
253 {
254         unsigned long val, res;
255         unsigned int i;
256
257         if (is_vlan_dev(dev))
258                 dev = vlan_dev_real_dev(dev);
259         res = dev->trans_start;
260         for (i = 0; i < dev->num_tx_queues; i++) {
261                 val = netdev_get_tx_queue(dev, i)->trans_start;
262                 if (val && time_after(val, res))
263                         res = val;
264         }
265         dev->trans_start = res;
266
267         return res;
268 }
269 EXPORT_SYMBOL(dev_trans_start);
270
271 static void dev_watchdog(unsigned long arg)
272 {
273         struct net_device *dev = (struct net_device *)arg;
274
275         netif_tx_lock(dev);
276         if (!qdisc_tx_is_noop(dev)) {
277                 if (netif_device_present(dev) &&
278                     netif_running(dev) &&
279                     netif_carrier_ok(dev)) {
280                         int some_queue_timedout = 0;
281                         unsigned int i;
282                         unsigned long trans_start;
283
284                         for (i = 0; i < dev->num_tx_queues; i++) {
285                                 struct netdev_queue *txq;
286
287                                 txq = netdev_get_tx_queue(dev, i);
288                                 /*
289                                  * old device drivers set dev->trans_start
290                                  */
291                                 trans_start = txq->trans_start ? : dev->trans_start;
292                                 if (netif_xmit_stopped(txq) &&
293                                     time_after(jiffies, (trans_start +
294                                                          dev->watchdog_timeo))) {
295                                         some_queue_timedout = 1;
296                                         txq->trans_timeout++;
297                                         break;
298                                 }
299                         }
300
301                         if (some_queue_timedout) {
302                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
303                                        dev->name, netdev_drivername(dev), i);
304                                 dev->netdev_ops->ndo_tx_timeout(dev);
305                         }
306                         if (!mod_timer(&dev->watchdog_timer,
307                                        round_jiffies(jiffies +
308                                                      dev->watchdog_timeo)))
309                                 dev_hold(dev);
310                 }
311         }
312         netif_tx_unlock(dev);
313
314         dev_put(dev);
315 }
316
317 void __netdev_watchdog_up(struct net_device *dev)
318 {
319         if (dev->netdev_ops->ndo_tx_timeout) {
320                 if (dev->watchdog_timeo <= 0)
321                         dev->watchdog_timeo = 5*HZ;
322                 if (!mod_timer(&dev->watchdog_timer,
323                                round_jiffies(jiffies + dev->watchdog_timeo)))
324                         dev_hold(dev);
325         }
326 }
327
328 static void dev_watchdog_up(struct net_device *dev)
329 {
330         __netdev_watchdog_up(dev);
331 }
332
333 static void dev_watchdog_down(struct net_device *dev)
334 {
335         netif_tx_lock_bh(dev);
336         if (del_timer(&dev->watchdog_timer))
337                 dev_put(dev);
338         netif_tx_unlock_bh(dev);
339 }
340
341 /**
342  *      netif_carrier_on - set carrier
343  *      @dev: network device
344  *
345  * Device has detected that carrier.
346  */
347 void netif_carrier_on(struct net_device *dev)
348 {
349         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
350                 if (dev->reg_state == NETREG_UNINITIALIZED)
351                         return;
352                 atomic_inc(&dev->carrier_changes);
353                 linkwatch_fire_event(dev);
354                 if (netif_running(dev))
355                         __netdev_watchdog_up(dev);
356         }
357 }
358 EXPORT_SYMBOL(netif_carrier_on);
359
360 /**
361  *      netif_carrier_off - clear carrier
362  *      @dev: network device
363  *
364  * Device has detected loss of carrier.
365  */
366 void netif_carrier_off(struct net_device *dev)
367 {
368         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
369                 if (dev->reg_state == NETREG_UNINITIALIZED)
370                         return;
371                 atomic_inc(&dev->carrier_changes);
372                 linkwatch_fire_event(dev);
373         }
374 }
375 EXPORT_SYMBOL(netif_carrier_off);
376
377 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
378    under all circumstances. It is difficult to invent anything faster or
379    cheaper.
380  */
381
382 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc)
383 {
384         kfree_skb(skb);
385         return NET_XMIT_CN;
386 }
387
388 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
389 {
390         return NULL;
391 }
392
393 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
394         .id             =       "noop",
395         .priv_size      =       0,
396         .enqueue        =       noop_enqueue,
397         .dequeue        =       noop_dequeue,
398         .peek           =       noop_dequeue,
399         .owner          =       THIS_MODULE,
400 };
401
402 static struct netdev_queue noop_netdev_queue = {
403         .qdisc          =       &noop_qdisc,
404         .qdisc_sleeping =       &noop_qdisc,
405 };
406
407 struct Qdisc noop_qdisc = {
408         .enqueue        =       noop_enqueue,
409         .dequeue        =       noop_dequeue,
410         .flags          =       TCQ_F_BUILTIN,
411         .ops            =       &noop_qdisc_ops,
412         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
413         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
414         .dev_queue      =       &noop_netdev_queue,
415         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
416 };
417 EXPORT_SYMBOL(noop_qdisc);
418
419 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
420         .id             =       "noqueue",
421         .priv_size      =       0,
422         .enqueue        =       noop_enqueue,
423         .dequeue        =       noop_dequeue,
424         .peek           =       noop_dequeue,
425         .owner          =       THIS_MODULE,
426 };
427
428 static struct Qdisc noqueue_qdisc;
429 static struct netdev_queue noqueue_netdev_queue = {
430         .qdisc          =       &noqueue_qdisc,
431         .qdisc_sleeping =       &noqueue_qdisc,
432 };
433
434 static struct Qdisc noqueue_qdisc = {
435         .enqueue        =       NULL,
436         .dequeue        =       noop_dequeue,
437         .flags          =       TCQ_F_BUILTIN,
438         .ops            =       &noqueue_qdisc_ops,
439         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
440         .q.lock         =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
441         .dev_queue      =       &noqueue_netdev_queue,
442         .busylock       =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.busylock),
443 };
444
445
446 static const u8 prio2band[TC_PRIO_MAX + 1] = {
447         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
448 };
449
450 /* 3-band FIFO queue: old style, but should be a bit faster than
451    generic prio+fifo combination.
452  */
453
454 #define PFIFO_FAST_BANDS 3
455
456 /*
457  * Private data for a pfifo_fast scheduler containing:
458  *      - queues for the three band
459  *      - bitmap indicating which of the bands contain skbs
460  */
461 struct pfifo_fast_priv {
462         u32 bitmap;
463         struct sk_buff_head q[PFIFO_FAST_BANDS];
464 };
465
466 /*
467  * Convert a bitmap to the first band number where an skb is queued, where:
468  *      bitmap=0 means there are no skbs on any band.
469  *      bitmap=1 means there is an skb on band 0.
470  *      bitmap=7 means there are skbs on all 3 bands, etc.
471  */
472 static const int bitmap2band[] = {-1, 0, 1, 0, 2, 0, 1, 0};
473
474 static inline struct sk_buff_head *band2list(struct pfifo_fast_priv *priv,
475                                              int band)
476 {
477         return priv->q + band;
478 }
479
480 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc)
481 {
482         if (skb_queue_len(&qdisc->q) < qdisc_dev(qdisc)->tx_queue_len) {
483                 int band = prio2band[skb->priority & TC_PRIO_MAX];
484                 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
485                 struct sk_buff_head *list = band2list(priv, band);
486
487                 priv->bitmap |= (1 << band);
488                 qdisc->q.qlen++;
489                 return __qdisc_enqueue_tail(skb, qdisc, list);
490         }
491
492         return qdisc_drop(skb, qdisc);
493 }
494
495 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
496 {
497         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
498         int band = bitmap2band[priv->bitmap];
499
500         if (likely(band >= 0)) {
501                 struct sk_buff_head *list = band2list(priv, band);
502                 struct sk_buff *skb = __qdisc_dequeue_head(qdisc, list);
503
504                 qdisc->q.qlen--;
505                 if (skb_queue_empty(list))
506                         priv->bitmap &= ~(1 << band);
507
508                 return skb;
509         }
510
511         return NULL;
512 }
513
514 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
515 {
516         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
517         int band = bitmap2band[priv->bitmap];
518
519         if (band >= 0) {
520                 struct sk_buff_head *list = band2list(priv, band);
521
522                 return skb_peek(list);
523         }
524
525         return NULL;
526 }
527
528 static void pfifo_fast_reset(struct Qdisc *qdisc)
529 {
530         int prio;
531         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
532
533         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
534                 __qdisc_reset_queue(qdisc, band2list(priv, prio));
535
536         priv->bitmap = 0;
537         qdisc->qstats.backlog = 0;
538         qdisc->q.qlen = 0;
539 }
540
541 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
542 {
543         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
544
545         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
546         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
547                 goto nla_put_failure;
548         return skb->len;
549
550 nla_put_failure:
551         return -1;
552 }
553
554 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
555 {
556         int prio;
557         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
558
559         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
560                 __skb_queue_head_init(band2list(priv, prio));
561
562         /* Can by-pass the queue discipline */
563         qdisc->flags |= TCQ_F_CAN_BYPASS;
564         return 0;
565 }
566
567 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
568         .id             =       "pfifo_fast",
569         .priv_size      =       sizeof(struct pfifo_fast_priv),
570         .enqueue        =       pfifo_fast_enqueue,
571         .dequeue        =       pfifo_fast_dequeue,
572         .peek           =       pfifo_fast_peek,
573         .init           =       pfifo_fast_init,
574         .reset          =       pfifo_fast_reset,
575         .dump           =       pfifo_fast_dump,
576         .owner          =       THIS_MODULE,
577 };
578
579 static struct lock_class_key qdisc_tx_busylock;
580
581 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
582                           const struct Qdisc_ops *ops)
583 {
584         void *p;
585         struct Qdisc *sch;
586         unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
587         int err = -ENOBUFS;
588         struct net_device *dev = dev_queue->dev;
589
590         p = kzalloc_node(size, GFP_KERNEL,
591                          netdev_queue_numa_node_read(dev_queue));
592
593         if (!p)
594                 goto errout;
595         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
596         /* if we got non aligned memory, ask more and do alignment ourself */
597         if (sch != p) {
598                 kfree(p);
599                 p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
600                                  netdev_queue_numa_node_read(dev_queue));
601                 if (!p)
602                         goto errout;
603                 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
604                 sch->padded = (char *) sch - (char *) p;
605         }
606         INIT_LIST_HEAD(&sch->list);
607         skb_queue_head_init(&sch->q);
608
609         spin_lock_init(&sch->busylock);
610         lockdep_set_class(&sch->busylock,
611                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
612
613         sch->ops = ops;
614         sch->enqueue = ops->enqueue;
615         sch->dequeue = ops->dequeue;
616         sch->dev_queue = dev_queue;
617         dev_hold(dev);
618         atomic_set(&sch->refcnt, 1);
619
620         return sch;
621 errout:
622         return ERR_PTR(err);
623 }
624
625 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
626                                 const struct Qdisc_ops *ops,
627                                 unsigned int parentid)
628 {
629         struct Qdisc *sch;
630
631         if (!try_module_get(ops->owner))
632                 goto errout;
633
634         sch = qdisc_alloc(dev_queue, ops);
635         if (IS_ERR(sch))
636                 goto errout;
637         sch->parent = parentid;
638
639         if (!ops->init || ops->init(sch, NULL) == 0)
640                 return sch;
641
642         qdisc_destroy(sch);
643 errout:
644         return NULL;
645 }
646 EXPORT_SYMBOL(qdisc_create_dflt);
647
648 /* Under qdisc_lock(qdisc) and BH! */
649
650 void qdisc_reset(struct Qdisc *qdisc)
651 {
652         const struct Qdisc_ops *ops = qdisc->ops;
653
654         if (ops->reset)
655                 ops->reset(qdisc);
656
657         if (qdisc->gso_skb) {
658                 kfree_skb_list(qdisc->gso_skb);
659                 qdisc->gso_skb = NULL;
660                 qdisc->q.qlen = 0;
661         }
662 }
663 EXPORT_SYMBOL(qdisc_reset);
664
665 static void qdisc_rcu_free(struct rcu_head *head)
666 {
667         struct Qdisc *qdisc = container_of(head, struct Qdisc, rcu_head);
668
669         if (qdisc_is_percpu_stats(qdisc))
670                 free_percpu(qdisc->cpu_bstats);
671
672         kfree((char *) qdisc - qdisc->padded);
673 }
674
675 void qdisc_destroy(struct Qdisc *qdisc)
676 {
677         const struct Qdisc_ops  *ops = qdisc->ops;
678
679         if (qdisc->flags & TCQ_F_BUILTIN ||
680             !atomic_dec_and_test(&qdisc->refcnt))
681                 return;
682
683 #ifdef CONFIG_NET_SCHED
684         qdisc_list_del(qdisc);
685
686         qdisc_put_stab(rtnl_dereference(qdisc->stab));
687 #endif
688         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
689         if (ops->reset)
690                 ops->reset(qdisc);
691         if (ops->destroy)
692                 ops->destroy(qdisc);
693
694         module_put(ops->owner);
695         dev_put(qdisc_dev(qdisc));
696
697         kfree_skb_list(qdisc->gso_skb);
698         /*
699          * gen_estimator est_timer() might access qdisc->q.lock,
700          * wait a RCU grace period before freeing qdisc.
701          */
702         call_rcu(&qdisc->rcu_head, qdisc_rcu_free);
703 }
704 EXPORT_SYMBOL(qdisc_destroy);
705
706 /* Attach toplevel qdisc to device queue. */
707 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
708                               struct Qdisc *qdisc)
709 {
710         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
711         spinlock_t *root_lock;
712
713         root_lock = qdisc_lock(oqdisc);
714         spin_lock_bh(root_lock);
715
716         /* Prune old scheduler */
717         if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1)
718                 qdisc_reset(oqdisc);
719
720         /* ... and graft new one */
721         if (qdisc == NULL)
722                 qdisc = &noop_qdisc;
723         dev_queue->qdisc_sleeping = qdisc;
724         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
725
726         spin_unlock_bh(root_lock);
727
728         return oqdisc;
729 }
730 EXPORT_SYMBOL(dev_graft_qdisc);
731
732 static void attach_one_default_qdisc(struct net_device *dev,
733                                      struct netdev_queue *dev_queue,
734                                      void *_unused)
735 {
736         struct Qdisc *qdisc = &noqueue_qdisc;
737
738         if (dev->tx_queue_len) {
739                 qdisc = qdisc_create_dflt(dev_queue,
740                                           default_qdisc_ops, TC_H_ROOT);
741                 if (!qdisc) {
742                         netdev_info(dev, "activation failed\n");
743                         return;
744                 }
745                 if (!netif_is_multiqueue(dev))
746                         qdisc->flags |= TCQ_F_ONETXQUEUE;
747         }
748         dev_queue->qdisc_sleeping = qdisc;
749 }
750
751 static void attach_default_qdiscs(struct net_device *dev)
752 {
753         struct netdev_queue *txq;
754         struct Qdisc *qdisc;
755
756         txq = netdev_get_tx_queue(dev, 0);
757
758         if (!netif_is_multiqueue(dev) || dev->tx_queue_len == 0) {
759                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
760                 dev->qdisc = txq->qdisc_sleeping;
761                 atomic_inc(&dev->qdisc->refcnt);
762         } else {
763                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT);
764                 if (qdisc) {
765                         dev->qdisc = qdisc;
766                         qdisc->ops->attach(qdisc);
767                 }
768         }
769 }
770
771 static void transition_one_qdisc(struct net_device *dev,
772                                  struct netdev_queue *dev_queue,
773                                  void *_need_watchdog)
774 {
775         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
776         int *need_watchdog_p = _need_watchdog;
777
778         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
779                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
780
781         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
782         if (need_watchdog_p && new_qdisc != &noqueue_qdisc) {
783                 dev_queue->trans_start = 0;
784                 *need_watchdog_p = 1;
785         }
786 }
787
788 void dev_activate(struct net_device *dev)
789 {
790         int need_watchdog;
791
792         /* No queueing discipline is attached to device;
793          * create default one for devices, which need queueing
794          * and noqueue_qdisc for virtual interfaces
795          */
796
797         if (dev->qdisc == &noop_qdisc)
798                 attach_default_qdiscs(dev);
799
800         if (!netif_carrier_ok(dev))
801                 /* Delay activation until next carrier-on event */
802                 return;
803
804         need_watchdog = 0;
805         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
806         if (dev_ingress_queue(dev))
807                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
808
809         if (need_watchdog) {
810                 dev->trans_start = jiffies;
811                 dev_watchdog_up(dev);
812         }
813 }
814 EXPORT_SYMBOL(dev_activate);
815
816 static void dev_deactivate_queue(struct net_device *dev,
817                                  struct netdev_queue *dev_queue,
818                                  void *_qdisc_default)
819 {
820         struct Qdisc *qdisc_default = _qdisc_default;
821         struct Qdisc *qdisc;
822
823         qdisc = rtnl_dereference(dev_queue->qdisc);
824         if (qdisc) {
825                 spin_lock_bh(qdisc_lock(qdisc));
826
827                 if (!(qdisc->flags & TCQ_F_BUILTIN))
828                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
829
830                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
831                 qdisc_reset(qdisc);
832
833                 spin_unlock_bh(qdisc_lock(qdisc));
834         }
835 }
836
837 static bool some_qdisc_is_busy(struct net_device *dev)
838 {
839         unsigned int i;
840
841         for (i = 0; i < dev->num_tx_queues; i++) {
842                 struct netdev_queue *dev_queue;
843                 spinlock_t *root_lock;
844                 struct Qdisc *q;
845                 int val;
846
847                 dev_queue = netdev_get_tx_queue(dev, i);
848                 q = dev_queue->qdisc_sleeping;
849                 root_lock = qdisc_lock(q);
850
851                 spin_lock_bh(root_lock);
852
853                 val = (qdisc_is_running(q) ||
854                        test_bit(__QDISC_STATE_SCHED, &q->state));
855
856                 spin_unlock_bh(root_lock);
857
858                 if (val)
859                         return true;
860         }
861         return false;
862 }
863
864 /**
865  *      dev_deactivate_many - deactivate transmissions on several devices
866  *      @head: list of devices to deactivate
867  *
868  *      This function returns only when all outstanding transmissions
869  *      have completed, unless all devices are in dismantle phase.
870  */
871 void dev_deactivate_many(struct list_head *head)
872 {
873         struct net_device *dev;
874         bool sync_needed = false;
875
876         list_for_each_entry(dev, head, close_list) {
877                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
878                                          &noop_qdisc);
879                 if (dev_ingress_queue(dev))
880                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
881                                              &noop_qdisc);
882
883                 dev_watchdog_down(dev);
884                 sync_needed |= !dev->dismantle;
885         }
886
887         /* Wait for outstanding qdisc-less dev_queue_xmit calls.
888          * This is avoided if all devices are in dismantle phase :
889          * Caller will call synchronize_net() for us
890          */
891         if (sync_needed)
892                 synchronize_net();
893
894         /* Wait for outstanding qdisc_run calls. */
895         list_for_each_entry(dev, head, close_list)
896                 while (some_qdisc_is_busy(dev))
897                         yield();
898 }
899
900 void dev_deactivate(struct net_device *dev)
901 {
902         LIST_HEAD(single);
903
904         list_add(&dev->close_list, &single);
905         dev_deactivate_many(&single);
906         list_del(&single);
907 }
908 EXPORT_SYMBOL(dev_deactivate);
909
910 static void dev_init_scheduler_queue(struct net_device *dev,
911                                      struct netdev_queue *dev_queue,
912                                      void *_qdisc)
913 {
914         struct Qdisc *qdisc = _qdisc;
915
916         rcu_assign_pointer(dev_queue->qdisc, qdisc);
917         dev_queue->qdisc_sleeping = qdisc;
918 }
919
920 void dev_init_scheduler(struct net_device *dev)
921 {
922         dev->qdisc = &noop_qdisc;
923         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
924         if (dev_ingress_queue(dev))
925                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
926
927         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
928 }
929
930 static void shutdown_scheduler_queue(struct net_device *dev,
931                                      struct netdev_queue *dev_queue,
932                                      void *_qdisc_default)
933 {
934         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
935         struct Qdisc *qdisc_default = _qdisc_default;
936
937         if (qdisc) {
938                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
939                 dev_queue->qdisc_sleeping = qdisc_default;
940
941                 qdisc_destroy(qdisc);
942         }
943 }
944
945 void dev_shutdown(struct net_device *dev)
946 {
947         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
948         if (dev_ingress_queue(dev))
949                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
950         qdisc_destroy(dev->qdisc);
951         dev->qdisc = &noop_qdisc;
952
953         WARN_ON(timer_pending(&dev->watchdog_timer));
954 }
955
956 void psched_ratecfg_precompute(struct psched_ratecfg *r,
957                                const struct tc_ratespec *conf,
958                                u64 rate64)
959 {
960         memset(r, 0, sizeof(*r));
961         r->overhead = conf->overhead;
962         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
963         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
964         r->mult = 1;
965         /*
966          * The deal here is to replace a divide by a reciprocal one
967          * in fast path (a reciprocal divide is a multiply and a shift)
968          *
969          * Normal formula would be :
970          *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
971          *
972          * We compute mult/shift to use instead :
973          *  time_in_ns = (len * mult) >> shift;
974          *
975          * We try to get the highest possible mult value for accuracy,
976          * but have to make sure no overflows will ever happen.
977          */
978         if (r->rate_bytes_ps > 0) {
979                 u64 factor = NSEC_PER_SEC;
980
981                 for (;;) {
982                         r->mult = div64_u64(factor, r->rate_bytes_ps);
983                         if (r->mult & (1U << 31) || factor & (1ULL << 63))
984                                 break;
985                         factor <<= 1;
986                         r->shift++;
987                 }
988         }
989 }
990 EXPORT_SYMBOL(psched_ratecfg_precompute);