GNU Linux-libre 4.19.211-gnu1
[releases.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 <linux/skb_array.h>
30 #include <linux/if_macvlan.h>
31 #include <net/sch_generic.h>
32 #include <net/pkt_sched.h>
33 #include <net/dst.h>
34 #include <trace/events/qdisc.h>
35 #include <net/xfrm.h>
36
37 /* Qdisc to use by default */
38 const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
39 EXPORT_SYMBOL(default_qdisc_ops);
40
41 /* Main transmission queue. */
42
43 /* Modifications to data participating in scheduling must be protected with
44  * qdisc_lock(qdisc) spinlock.
45  *
46  * The idea is the following:
47  * - enqueue, dequeue are serialized via qdisc root lock
48  * - ingress filtering is also serialized via qdisc root lock
49  * - updates to tree and tree walking are only done under the rtnl mutex.
50  */
51
52 #define SKB_XOFF_MAGIC ((struct sk_buff *)1UL)
53
54 static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
55 {
56         const struct netdev_queue *txq = q->dev_queue;
57         spinlock_t *lock = NULL;
58         struct sk_buff *skb;
59
60         if (q->flags & TCQ_F_NOLOCK) {
61                 lock = qdisc_lock(q);
62                 spin_lock(lock);
63         }
64
65         skb = skb_peek(&q->skb_bad_txq);
66         if (skb) {
67                 /* check the reason of requeuing without tx lock first */
68                 txq = skb_get_tx_queue(txq->dev, skb);
69                 if (!netif_xmit_frozen_or_stopped(txq)) {
70                         skb = __skb_dequeue(&q->skb_bad_txq);
71                         if (qdisc_is_percpu_stats(q)) {
72                                 qdisc_qstats_cpu_backlog_dec(q, skb);
73                                 qdisc_qstats_atomic_qlen_dec(q);
74                         } else {
75                                 qdisc_qstats_backlog_dec(q, skb);
76                                 q->q.qlen--;
77                         }
78                 } else {
79                         skb = SKB_XOFF_MAGIC;
80                 }
81         }
82
83         if (lock)
84                 spin_unlock(lock);
85
86         return skb;
87 }
88
89 static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
90 {
91         struct sk_buff *skb = skb_peek(&q->skb_bad_txq);
92
93         if (unlikely(skb))
94                 skb = __skb_dequeue_bad_txq(q);
95
96         return skb;
97 }
98
99 static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
100                                              struct sk_buff *skb)
101 {
102         spinlock_t *lock = NULL;
103
104         if (q->flags & TCQ_F_NOLOCK) {
105                 lock = qdisc_lock(q);
106                 spin_lock(lock);
107         }
108
109         __skb_queue_tail(&q->skb_bad_txq, skb);
110
111         if (qdisc_is_percpu_stats(q)) {
112                 qdisc_qstats_cpu_backlog_inc(q, skb);
113                 qdisc_qstats_atomic_qlen_inc(q);
114         } else {
115                 qdisc_qstats_backlog_inc(q, skb);
116                 q->q.qlen++;
117         }
118
119         if (lock)
120                 spin_unlock(lock);
121 }
122
123 static inline int __dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
124 {
125         while (skb) {
126                 struct sk_buff *next = skb->next;
127
128                 __skb_queue_tail(&q->gso_skb, skb);
129                 q->qstats.requeues++;
130                 qdisc_qstats_backlog_inc(q, skb);
131                 q->q.qlen++;    /* it's still part of the queue */
132
133                 skb = next;
134         }
135         __netif_schedule(q);
136
137         return 0;
138 }
139
140 static inline int dev_requeue_skb_locked(struct sk_buff *skb, struct Qdisc *q)
141 {
142         spinlock_t *lock = qdisc_lock(q);
143
144         spin_lock(lock);
145         while (skb) {
146                 struct sk_buff *next = skb->next;
147
148                 __skb_queue_tail(&q->gso_skb, skb);
149
150                 qdisc_qstats_cpu_requeues_inc(q);
151                 qdisc_qstats_cpu_backlog_inc(q, skb);
152                 qdisc_qstats_atomic_qlen_inc(q);
153
154                 skb = next;
155         }
156         spin_unlock(lock);
157
158         __netif_schedule(q);
159
160         return 0;
161 }
162
163 static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
164 {
165         if (q->flags & TCQ_F_NOLOCK)
166                 return dev_requeue_skb_locked(skb, q);
167         else
168                 return __dev_requeue_skb(skb, q);
169 }
170
171 static void try_bulk_dequeue_skb(struct Qdisc *q,
172                                  struct sk_buff *skb,
173                                  const struct netdev_queue *txq,
174                                  int *packets)
175 {
176         int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
177
178         while (bytelimit > 0) {
179                 struct sk_buff *nskb = q->dequeue(q);
180
181                 if (!nskb)
182                         break;
183
184                 bytelimit -= nskb->len; /* covers GSO len */
185                 skb->next = nskb;
186                 skb = nskb;
187                 (*packets)++; /* GSO counts as one pkt */
188         }
189         skb->next = NULL;
190 }
191
192 /* This variant of try_bulk_dequeue_skb() makes sure
193  * all skbs in the chain are for the same txq
194  */
195 static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
196                                       struct sk_buff *skb,
197                                       int *packets)
198 {
199         int mapping = skb_get_queue_mapping(skb);
200         struct sk_buff *nskb;
201         int cnt = 0;
202
203         do {
204                 nskb = q->dequeue(q);
205                 if (!nskb)
206                         break;
207                 if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
208                         qdisc_enqueue_skb_bad_txq(q, nskb);
209                         break;
210                 }
211                 skb->next = nskb;
212                 skb = nskb;
213         } while (++cnt < 8);
214         (*packets) += cnt;
215         skb->next = NULL;
216 }
217
218 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
219  * A requeued skb (via q->gso_skb) can also be a SKB list.
220  */
221 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
222                                    int *packets)
223 {
224         const struct netdev_queue *txq = q->dev_queue;
225         struct sk_buff *skb = NULL;
226
227         *packets = 1;
228         if (unlikely(!skb_queue_empty(&q->gso_skb))) {
229                 spinlock_t *lock = NULL;
230
231                 if (q->flags & TCQ_F_NOLOCK) {
232                         lock = qdisc_lock(q);
233                         spin_lock(lock);
234                 }
235
236                 skb = skb_peek(&q->gso_skb);
237
238                 /* skb may be null if another cpu pulls gso_skb off in between
239                  * empty check and lock.
240                  */
241                 if (!skb) {
242                         if (lock)
243                                 spin_unlock(lock);
244                         goto validate;
245                 }
246
247                 /* skb in gso_skb were already validated */
248                 *validate = false;
249                 if (xfrm_offload(skb))
250                         *validate = true;
251                 /* check the reason of requeuing without tx lock first */
252                 txq = skb_get_tx_queue(txq->dev, skb);
253                 if (!netif_xmit_frozen_or_stopped(txq)) {
254                         skb = __skb_dequeue(&q->gso_skb);
255                         if (qdisc_is_percpu_stats(q)) {
256                                 qdisc_qstats_cpu_backlog_dec(q, skb);
257                                 qdisc_qstats_atomic_qlen_dec(q);
258                         } else {
259                                 qdisc_qstats_backlog_dec(q, skb);
260                                 q->q.qlen--;
261                         }
262                 } else {
263                         skb = NULL;
264                 }
265                 if (lock)
266                         spin_unlock(lock);
267                 goto trace;
268         }
269 validate:
270         *validate = true;
271
272         if ((q->flags & TCQ_F_ONETXQUEUE) &&
273             netif_xmit_frozen_or_stopped(txq))
274                 return skb;
275
276         skb = qdisc_dequeue_skb_bad_txq(q);
277         if (unlikely(skb)) {
278                 if (skb == SKB_XOFF_MAGIC)
279                         return NULL;
280                 goto bulk;
281         }
282         skb = q->dequeue(q);
283         if (skb) {
284 bulk:
285                 if (qdisc_may_bulk(q))
286                         try_bulk_dequeue_skb(q, skb, txq, packets);
287                 else
288                         try_bulk_dequeue_skb_slow(q, skb, packets);
289         }
290 trace:
291         trace_qdisc_dequeue(q, txq, *packets, skb);
292         return skb;
293 }
294
295 /*
296  * Transmit possibly several skbs, and handle the return status as
297  * required. Owning running seqcount bit guarantees that
298  * only one CPU can execute this function.
299  *
300  * Returns to the caller:
301  *                              false  - hardware queue frozen backoff
302  *                              true   - feel free to send more pkts
303  */
304 bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
305                      struct net_device *dev, struct netdev_queue *txq,
306                      spinlock_t *root_lock, bool validate)
307 {
308         int ret = NETDEV_TX_BUSY;
309         bool again = false;
310
311         /* And release qdisc */
312         if (root_lock)
313                 spin_unlock(root_lock);
314
315         /* Note that we validate skb (GSO, checksum, ...) outside of locks */
316         if (validate)
317                 skb = validate_xmit_skb_list(skb, dev, &again);
318
319 #ifdef CONFIG_XFRM_OFFLOAD
320         if (unlikely(again)) {
321                 if (root_lock)
322                         spin_lock(root_lock);
323
324                 dev_requeue_skb(skb, q);
325                 return false;
326         }
327 #endif
328
329         if (likely(skb)) {
330                 HARD_TX_LOCK(dev, txq, smp_processor_id());
331                 if (!netif_xmit_frozen_or_stopped(txq))
332                         skb = dev_hard_start_xmit(skb, dev, txq, &ret);
333
334                 HARD_TX_UNLOCK(dev, txq);
335         } else {
336                 if (root_lock)
337                         spin_lock(root_lock);
338                 return true;
339         }
340
341         if (root_lock)
342                 spin_lock(root_lock);
343
344         if (!dev_xmit_complete(ret)) {
345                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
346                 if (unlikely(ret != NETDEV_TX_BUSY))
347                         net_warn_ratelimited("BUG %s code %d qlen %d\n",
348                                              dev->name, ret, q->q.qlen);
349
350                 dev_requeue_skb(skb, q);
351                 return false;
352         }
353
354         return true;
355 }
356
357 /*
358  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
359  *
360  * running seqcount guarantees only one CPU can process
361  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
362  * this queue.
363  *
364  *  netif_tx_lock serializes accesses to device driver.
365  *
366  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
367  *  if one is grabbed, another must be free.
368  *
369  * Note, that this procedure can be called by a watchdog timer
370  *
371  * Returns to the caller:
372  *                              0  - queue is empty or throttled.
373  *                              >0 - queue is not empty.
374  *
375  */
376 static inline bool qdisc_restart(struct Qdisc *q, int *packets)
377 {
378         spinlock_t *root_lock = NULL;
379         struct netdev_queue *txq;
380         struct net_device *dev;
381         struct sk_buff *skb;
382         bool validate;
383
384         /* Dequeue packet */
385         skb = dequeue_skb(q, &validate, packets);
386         if (unlikely(!skb))
387                 return false;
388
389         if (!(q->flags & TCQ_F_NOLOCK))
390                 root_lock = qdisc_lock(q);
391
392         dev = qdisc_dev(q);
393         txq = skb_get_tx_queue(dev, skb);
394
395         return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
396 }
397
398 void __qdisc_run(struct Qdisc *q)
399 {
400         int quota = dev_tx_weight;
401         int packets;
402
403         while (qdisc_restart(q, &packets)) {
404                 /*
405                  * Ordered by possible occurrence: Postpone processing if
406                  * 1. we've exceeded packet quota
407                  * 2. another process needs the CPU;
408                  */
409                 quota -= packets;
410                 if (quota <= 0 || need_resched()) {
411                         __netif_schedule(q);
412                         break;
413                 }
414         }
415 }
416
417 unsigned long dev_trans_start(struct net_device *dev)
418 {
419         unsigned long val, res;
420         unsigned int i;
421
422         if (is_vlan_dev(dev))
423                 dev = vlan_dev_real_dev(dev);
424         else if (netif_is_macvlan(dev))
425                 dev = macvlan_dev_real_dev(dev);
426         res = netdev_get_tx_queue(dev, 0)->trans_start;
427         for (i = 1; i < dev->num_tx_queues; i++) {
428                 val = netdev_get_tx_queue(dev, i)->trans_start;
429                 if (val && time_after(val, res))
430                         res = val;
431         }
432
433         return res;
434 }
435 EXPORT_SYMBOL(dev_trans_start);
436
437 static void dev_watchdog(struct timer_list *t)
438 {
439         struct net_device *dev = from_timer(dev, t, watchdog_timer);
440
441         netif_tx_lock(dev);
442         if (!qdisc_tx_is_noop(dev)) {
443                 if (netif_device_present(dev) &&
444                     netif_running(dev) &&
445                     netif_carrier_ok(dev)) {
446                         int some_queue_timedout = 0;
447                         unsigned int i;
448                         unsigned long trans_start;
449
450                         for (i = 0; i < dev->num_tx_queues; i++) {
451                                 struct netdev_queue *txq;
452
453                                 txq = netdev_get_tx_queue(dev, i);
454                                 trans_start = txq->trans_start;
455                                 if (netif_xmit_stopped(txq) &&
456                                     time_after(jiffies, (trans_start +
457                                                          dev->watchdog_timeo))) {
458                                         some_queue_timedout = 1;
459                                         txq->trans_timeout++;
460                                         break;
461                                 }
462                         }
463
464                         if (some_queue_timedout) {
465                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
466                                        dev->name, netdev_drivername(dev), i);
467                                 dev->netdev_ops->ndo_tx_timeout(dev);
468                         }
469                         if (!mod_timer(&dev->watchdog_timer,
470                                        round_jiffies(jiffies +
471                                                      dev->watchdog_timeo)))
472                                 dev_hold(dev);
473                 }
474         }
475         netif_tx_unlock(dev);
476
477         dev_put(dev);
478 }
479
480 void __netdev_watchdog_up(struct net_device *dev)
481 {
482         if (dev->netdev_ops->ndo_tx_timeout) {
483                 if (dev->watchdog_timeo <= 0)
484                         dev->watchdog_timeo = 5*HZ;
485                 if (!mod_timer(&dev->watchdog_timer,
486                                round_jiffies(jiffies + dev->watchdog_timeo)))
487                         dev_hold(dev);
488         }
489 }
490 EXPORT_SYMBOL_GPL(__netdev_watchdog_up);
491
492 static void dev_watchdog_up(struct net_device *dev)
493 {
494         __netdev_watchdog_up(dev);
495 }
496
497 static void dev_watchdog_down(struct net_device *dev)
498 {
499         netif_tx_lock_bh(dev);
500         if (del_timer(&dev->watchdog_timer))
501                 dev_put(dev);
502         netif_tx_unlock_bh(dev);
503 }
504
505 /**
506  *      netif_carrier_on - set carrier
507  *      @dev: network device
508  *
509  * Device has detected that carrier.
510  */
511 void netif_carrier_on(struct net_device *dev)
512 {
513         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
514                 if (dev->reg_state == NETREG_UNINITIALIZED)
515                         return;
516                 atomic_inc(&dev->carrier_up_count);
517                 linkwatch_fire_event(dev);
518                 if (netif_running(dev))
519                         __netdev_watchdog_up(dev);
520         }
521 }
522 EXPORT_SYMBOL(netif_carrier_on);
523
524 /**
525  *      netif_carrier_off - clear carrier
526  *      @dev: network device
527  *
528  * Device has detected loss of carrier.
529  */
530 void netif_carrier_off(struct net_device *dev)
531 {
532         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
533                 if (dev->reg_state == NETREG_UNINITIALIZED)
534                         return;
535                 atomic_inc(&dev->carrier_down_count);
536                 linkwatch_fire_event(dev);
537         }
538 }
539 EXPORT_SYMBOL(netif_carrier_off);
540
541 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
542    under all circumstances. It is difficult to invent anything faster or
543    cheaper.
544  */
545
546 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
547                         struct sk_buff **to_free)
548 {
549         __qdisc_drop(skb, to_free);
550         return NET_XMIT_CN;
551 }
552
553 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
554 {
555         return NULL;
556 }
557
558 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
559         .id             =       "noop",
560         .priv_size      =       0,
561         .enqueue        =       noop_enqueue,
562         .dequeue        =       noop_dequeue,
563         .peek           =       noop_dequeue,
564         .owner          =       THIS_MODULE,
565 };
566
567 static struct netdev_queue noop_netdev_queue = {
568         .qdisc          =       &noop_qdisc,
569         .qdisc_sleeping =       &noop_qdisc,
570 };
571
572 struct Qdisc noop_qdisc = {
573         .enqueue        =       noop_enqueue,
574         .dequeue        =       noop_dequeue,
575         .flags          =       TCQ_F_BUILTIN,
576         .ops            =       &noop_qdisc_ops,
577         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
578         .dev_queue      =       &noop_netdev_queue,
579         .running        =       SEQCNT_ZERO(noop_qdisc.running),
580         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
581         .gso_skb = {
582                 .next = (struct sk_buff *)&noop_qdisc.gso_skb,
583                 .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
584                 .qlen = 0,
585                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
586         },
587         .skb_bad_txq = {
588                 .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
589                 .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
590                 .qlen = 0,
591                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
592         },
593 };
594 EXPORT_SYMBOL(noop_qdisc);
595
596 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
597                         struct netlink_ext_ack *extack)
598 {
599         /* register_qdisc() assigns a default of noop_enqueue if unset,
600          * but __dev_queue_xmit() treats noqueue only as such
601          * if this is NULL - so clear it here. */
602         qdisc->enqueue = NULL;
603         return 0;
604 }
605
606 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
607         .id             =       "noqueue",
608         .priv_size      =       0,
609         .init           =       noqueue_init,
610         .enqueue        =       noop_enqueue,
611         .dequeue        =       noop_dequeue,
612         .peek           =       noop_dequeue,
613         .owner          =       THIS_MODULE,
614 };
615
616 static const u8 prio2band[TC_PRIO_MAX + 1] = {
617         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
618 };
619
620 /* 3-band FIFO queue: old style, but should be a bit faster than
621    generic prio+fifo combination.
622  */
623
624 #define PFIFO_FAST_BANDS 3
625
626 /*
627  * Private data for a pfifo_fast scheduler containing:
628  *      - rings for priority bands
629  */
630 struct pfifo_fast_priv {
631         struct skb_array q[PFIFO_FAST_BANDS];
632 };
633
634 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
635                                           int band)
636 {
637         return &priv->q[band];
638 }
639
640 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
641                               struct sk_buff **to_free)
642 {
643         int band = prio2band[skb->priority & TC_PRIO_MAX];
644         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
645         struct skb_array *q = band2list(priv, band);
646         unsigned int pkt_len = qdisc_pkt_len(skb);
647         int err;
648
649         err = skb_array_produce(q, skb);
650
651         if (unlikely(err))
652                 return qdisc_drop_cpu(skb, qdisc, to_free);
653
654         qdisc_qstats_atomic_qlen_inc(qdisc);
655         /* Note: skb can not be used after skb_array_produce(),
656          * so we better not use qdisc_qstats_cpu_backlog_inc()
657          */
658         this_cpu_add(qdisc->cpu_qstats->backlog, pkt_len);
659         return NET_XMIT_SUCCESS;
660 }
661
662 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
663 {
664         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
665         struct sk_buff *skb = NULL;
666         int band;
667
668         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
669                 struct skb_array *q = band2list(priv, band);
670
671                 if (__skb_array_empty(q))
672                         continue;
673
674                 skb = __skb_array_consume(q);
675         }
676         if (likely(skb)) {
677                 qdisc_qstats_cpu_backlog_dec(qdisc, skb);
678                 qdisc_bstats_cpu_update(qdisc, skb);
679                 qdisc_qstats_atomic_qlen_dec(qdisc);
680         }
681
682         return skb;
683 }
684
685 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
686 {
687         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
688         struct sk_buff *skb = NULL;
689         int band;
690
691         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
692                 struct skb_array *q = band2list(priv, band);
693
694                 skb = __skb_array_peek(q);
695         }
696
697         return skb;
698 }
699
700 static void pfifo_fast_reset(struct Qdisc *qdisc)
701 {
702         int i, band;
703         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
704
705         for (band = 0; band < PFIFO_FAST_BANDS; band++) {
706                 struct skb_array *q = band2list(priv, band);
707                 struct sk_buff *skb;
708
709                 /* NULL ring is possible if destroy path is due to a failed
710                  * skb_array_init() in pfifo_fast_init() case.
711                  */
712                 if (!q->ring.queue)
713                         continue;
714
715                 while ((skb = __skb_array_consume(q)) != NULL)
716                         kfree_skb(skb);
717         }
718
719         for_each_possible_cpu(i) {
720                 struct gnet_stats_queue *q = per_cpu_ptr(qdisc->cpu_qstats, i);
721
722                 q->backlog = 0;
723         }
724 }
725
726 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
727 {
728         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
729
730         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
731         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
732                 goto nla_put_failure;
733         return skb->len;
734
735 nla_put_failure:
736         return -1;
737 }
738
739 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
740                            struct netlink_ext_ack *extack)
741 {
742         unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
743         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
744         int prio;
745
746         /* guard against zero length rings */
747         if (!qlen)
748                 return -EINVAL;
749
750         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
751                 struct skb_array *q = band2list(priv, prio);
752                 int err;
753
754                 err = skb_array_init(q, qlen, GFP_KERNEL);
755                 if (err)
756                         return -ENOMEM;
757         }
758
759         /* Can by-pass the queue discipline */
760         qdisc->flags |= TCQ_F_CAN_BYPASS;
761         return 0;
762 }
763
764 static void pfifo_fast_destroy(struct Qdisc *sch)
765 {
766         struct pfifo_fast_priv *priv = qdisc_priv(sch);
767         int prio;
768
769         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
770                 struct skb_array *q = band2list(priv, prio);
771
772                 /* NULL ring is possible if destroy path is due to a failed
773                  * skb_array_init() in pfifo_fast_init() case.
774                  */
775                 if (!q->ring.queue)
776                         continue;
777                 /* Destroy ring but no need to kfree_skb because a call to
778                  * pfifo_fast_reset() has already done that work.
779                  */
780                 ptr_ring_cleanup(&q->ring, NULL);
781         }
782 }
783
784 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
785                                           unsigned int new_len)
786 {
787         struct pfifo_fast_priv *priv = qdisc_priv(sch);
788         struct skb_array *bands[PFIFO_FAST_BANDS];
789         int prio;
790
791         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
792                 struct skb_array *q = band2list(priv, prio);
793
794                 bands[prio] = q;
795         }
796
797         return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
798                                          GFP_KERNEL);
799 }
800
801 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
802         .id             =       "pfifo_fast",
803         .priv_size      =       sizeof(struct pfifo_fast_priv),
804         .enqueue        =       pfifo_fast_enqueue,
805         .dequeue        =       pfifo_fast_dequeue,
806         .peek           =       pfifo_fast_peek,
807         .init           =       pfifo_fast_init,
808         .destroy        =       pfifo_fast_destroy,
809         .reset          =       pfifo_fast_reset,
810         .dump           =       pfifo_fast_dump,
811         .change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
812         .owner          =       THIS_MODULE,
813         .static_flags   =       TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
814 };
815 EXPORT_SYMBOL(pfifo_fast_ops);
816
817 static struct lock_class_key qdisc_tx_busylock;
818 static struct lock_class_key qdisc_running_key;
819
820 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
821                           const struct Qdisc_ops *ops,
822                           struct netlink_ext_ack *extack)
823 {
824         void *p;
825         struct Qdisc *sch;
826         unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
827         int err = -ENOBUFS;
828         struct net_device *dev;
829
830         if (!dev_queue) {
831                 NL_SET_ERR_MSG(extack, "No device queue given");
832                 err = -EINVAL;
833                 goto errout;
834         }
835
836         dev = dev_queue->dev;
837         p = kzalloc_node(size, GFP_KERNEL,
838                          netdev_queue_numa_node_read(dev_queue));
839
840         if (!p)
841                 goto errout;
842         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
843         /* if we got non aligned memory, ask more and do alignment ourself */
844         if (sch != p) {
845                 kfree(p);
846                 p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
847                                  netdev_queue_numa_node_read(dev_queue));
848                 if (!p)
849                         goto errout;
850                 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
851                 sch->padded = (char *) sch - (char *) p;
852         }
853         __skb_queue_head_init(&sch->gso_skb);
854         __skb_queue_head_init(&sch->skb_bad_txq);
855         qdisc_skb_head_init(&sch->q);
856         spin_lock_init(&sch->q.lock);
857
858         if (ops->static_flags & TCQ_F_CPUSTATS) {
859                 sch->cpu_bstats =
860                         netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
861                 if (!sch->cpu_bstats)
862                         goto errout1;
863
864                 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
865                 if (!sch->cpu_qstats) {
866                         free_percpu(sch->cpu_bstats);
867                         goto errout1;
868                 }
869         }
870
871         spin_lock_init(&sch->busylock);
872         lockdep_set_class(&sch->busylock,
873                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
874
875         /* seqlock has the same scope of busylock, for NOLOCK qdisc */
876         spin_lock_init(&sch->seqlock);
877         lockdep_set_class(&sch->busylock,
878                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
879
880         seqcount_init(&sch->running);
881         lockdep_set_class(&sch->running,
882                           dev->qdisc_running_key ?: &qdisc_running_key);
883
884         sch->ops = ops;
885         sch->flags = ops->static_flags;
886         sch->enqueue = ops->enqueue;
887         sch->dequeue = ops->dequeue;
888         sch->dev_queue = dev_queue;
889         dev_hold(dev);
890         refcount_set(&sch->refcnt, 1);
891
892         return sch;
893 errout1:
894         kfree(p);
895 errout:
896         return ERR_PTR(err);
897 }
898
899 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
900                                 const struct Qdisc_ops *ops,
901                                 unsigned int parentid,
902                                 struct netlink_ext_ack *extack)
903 {
904         struct Qdisc *sch;
905
906         if (!try_module_get(ops->owner)) {
907                 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
908                 return NULL;
909         }
910
911         sch = qdisc_alloc(dev_queue, ops, extack);
912         if (IS_ERR(sch)) {
913                 module_put(ops->owner);
914                 return NULL;
915         }
916         sch->parent = parentid;
917
918         if (!ops->init || ops->init(sch, NULL, extack) == 0)
919                 return sch;
920
921         qdisc_destroy(sch);
922         return NULL;
923 }
924 EXPORT_SYMBOL(qdisc_create_dflt);
925
926 /* Under qdisc_lock(qdisc) and BH! */
927
928 void qdisc_reset(struct Qdisc *qdisc)
929 {
930         const struct Qdisc_ops *ops = qdisc->ops;
931         struct sk_buff *skb, *tmp;
932
933         if (ops->reset)
934                 ops->reset(qdisc);
935
936         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
937                 __skb_unlink(skb, &qdisc->gso_skb);
938                 kfree_skb_list(skb);
939         }
940
941         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
942                 __skb_unlink(skb, &qdisc->skb_bad_txq);
943                 kfree_skb_list(skb);
944         }
945
946         qdisc->q.qlen = 0;
947         qdisc->qstats.backlog = 0;
948 }
949 EXPORT_SYMBOL(qdisc_reset);
950
951 void qdisc_free(struct Qdisc *qdisc)
952 {
953         if (qdisc_is_percpu_stats(qdisc)) {
954                 free_percpu(qdisc->cpu_bstats);
955                 free_percpu(qdisc->cpu_qstats);
956         }
957
958         kfree((char *) qdisc - qdisc->padded);
959 }
960
961 void qdisc_destroy(struct Qdisc *qdisc)
962 {
963         const struct Qdisc_ops *ops;
964         struct sk_buff *skb, *tmp;
965
966         if (!qdisc)
967                 return;
968         ops = qdisc->ops;
969
970         if (qdisc->flags & TCQ_F_BUILTIN ||
971             !refcount_dec_and_test(&qdisc->refcnt))
972                 return;
973
974 #ifdef CONFIG_NET_SCHED
975         qdisc_hash_del(qdisc);
976
977         qdisc_put_stab(rtnl_dereference(qdisc->stab));
978 #endif
979         gen_kill_estimator(&qdisc->rate_est);
980         if (ops->reset)
981                 ops->reset(qdisc);
982         if (ops->destroy)
983                 ops->destroy(qdisc);
984
985         module_put(ops->owner);
986         dev_put(qdisc_dev(qdisc));
987
988         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
989                 __skb_unlink(skb, &qdisc->gso_skb);
990                 kfree_skb_list(skb);
991         }
992
993         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
994                 __skb_unlink(skb, &qdisc->skb_bad_txq);
995                 kfree_skb_list(skb);
996         }
997
998         qdisc_free(qdisc);
999 }
1000 EXPORT_SYMBOL(qdisc_destroy);
1001
1002 /* Attach toplevel qdisc to device queue. */
1003 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
1004                               struct Qdisc *qdisc)
1005 {
1006         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
1007         spinlock_t *root_lock;
1008
1009         root_lock = qdisc_lock(oqdisc);
1010         spin_lock_bh(root_lock);
1011
1012         /* ... and graft new one */
1013         if (qdisc == NULL)
1014                 qdisc = &noop_qdisc;
1015         dev_queue->qdisc_sleeping = qdisc;
1016         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1017
1018         spin_unlock_bh(root_lock);
1019
1020         return oqdisc;
1021 }
1022 EXPORT_SYMBOL(dev_graft_qdisc);
1023
1024 static void attach_one_default_qdisc(struct net_device *dev,
1025                                      struct netdev_queue *dev_queue,
1026                                      void *_unused)
1027 {
1028         struct Qdisc *qdisc;
1029         const struct Qdisc_ops *ops = default_qdisc_ops;
1030
1031         if (dev->priv_flags & IFF_NO_QUEUE)
1032                 ops = &noqueue_qdisc_ops;
1033
1034         qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1035         if (!qdisc) {
1036                 netdev_info(dev, "activation failed\n");
1037                 return;
1038         }
1039         if (!netif_is_multiqueue(dev))
1040                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1041         dev_queue->qdisc_sleeping = qdisc;
1042 }
1043
1044 static void attach_default_qdiscs(struct net_device *dev)
1045 {
1046         struct netdev_queue *txq;
1047         struct Qdisc *qdisc;
1048
1049         txq = netdev_get_tx_queue(dev, 0);
1050
1051         if (!netif_is_multiqueue(dev) ||
1052             dev->priv_flags & IFF_NO_QUEUE) {
1053                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1054                 dev->qdisc = txq->qdisc_sleeping;
1055                 qdisc_refcount_inc(dev->qdisc);
1056         } else {
1057                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1058                 if (qdisc) {
1059                         dev->qdisc = qdisc;
1060                         qdisc->ops->attach(qdisc);
1061                 }
1062         }
1063 #ifdef CONFIG_NET_SCHED
1064         if (dev->qdisc != &noop_qdisc)
1065                 qdisc_hash_add(dev->qdisc, false);
1066 #endif
1067 }
1068
1069 static void transition_one_qdisc(struct net_device *dev,
1070                                  struct netdev_queue *dev_queue,
1071                                  void *_need_watchdog)
1072 {
1073         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1074         int *need_watchdog_p = _need_watchdog;
1075
1076         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1077                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1078
1079         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1080         if (need_watchdog_p) {
1081                 dev_queue->trans_start = 0;
1082                 *need_watchdog_p = 1;
1083         }
1084 }
1085
1086 void dev_activate(struct net_device *dev)
1087 {
1088         int need_watchdog;
1089
1090         /* No queueing discipline is attached to device;
1091          * create default one for devices, which need queueing
1092          * and noqueue_qdisc for virtual interfaces
1093          */
1094
1095         if (dev->qdisc == &noop_qdisc)
1096                 attach_default_qdiscs(dev);
1097
1098         if (!netif_carrier_ok(dev))
1099                 /* Delay activation until next carrier-on event */
1100                 return;
1101
1102         need_watchdog = 0;
1103         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1104         if (dev_ingress_queue(dev))
1105                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1106
1107         if (need_watchdog) {
1108                 netif_trans_update(dev);
1109                 dev_watchdog_up(dev);
1110         }
1111 }
1112 EXPORT_SYMBOL(dev_activate);
1113
1114 static void dev_deactivate_queue(struct net_device *dev,
1115                                  struct netdev_queue *dev_queue,
1116                                  void *_qdisc_default)
1117 {
1118         struct Qdisc *qdisc = rtnl_dereference(dev_queue->qdisc);
1119         struct Qdisc *qdisc_default = _qdisc_default;
1120
1121         if (qdisc) {
1122                 if (!(qdisc->flags & TCQ_F_BUILTIN))
1123                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1124
1125                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1126         }
1127 }
1128
1129 static void dev_reset_queue(struct net_device *dev,
1130                             struct netdev_queue *dev_queue,
1131                             void *_unused)
1132 {
1133         struct Qdisc *qdisc;
1134         bool nolock;
1135
1136         qdisc = dev_queue->qdisc_sleeping;
1137         if (!qdisc)
1138                 return;
1139
1140         nolock = qdisc->flags & TCQ_F_NOLOCK;
1141
1142         if (nolock)
1143                 spin_lock_bh(&qdisc->seqlock);
1144         spin_lock_bh(qdisc_lock(qdisc));
1145
1146         qdisc_reset(qdisc);
1147
1148         spin_unlock_bh(qdisc_lock(qdisc));
1149         if (nolock)
1150                 spin_unlock_bh(&qdisc->seqlock);
1151 }
1152
1153 static bool some_qdisc_is_busy(struct net_device *dev)
1154 {
1155         unsigned int i;
1156
1157         for (i = 0; i < dev->num_tx_queues; i++) {
1158                 struct netdev_queue *dev_queue;
1159                 spinlock_t *root_lock;
1160                 struct Qdisc *q;
1161                 int val;
1162
1163                 dev_queue = netdev_get_tx_queue(dev, i);
1164                 q = dev_queue->qdisc_sleeping;
1165
1166                 root_lock = qdisc_lock(q);
1167                 spin_lock_bh(root_lock);
1168
1169                 val = (qdisc_is_running(q) ||
1170                        test_bit(__QDISC_STATE_SCHED, &q->state));
1171
1172                 spin_unlock_bh(root_lock);
1173
1174                 if (val)
1175                         return true;
1176         }
1177         return false;
1178 }
1179
1180 static void dev_qdisc_reset(struct net_device *dev,
1181                             struct netdev_queue *dev_queue,
1182                             void *none)
1183 {
1184         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1185
1186         if (qdisc)
1187                 qdisc_reset(qdisc);
1188 }
1189
1190 /**
1191  *      dev_deactivate_many - deactivate transmissions on several devices
1192  *      @head: list of devices to deactivate
1193  *
1194  *      This function returns only when all outstanding transmissions
1195  *      have completed, unless all devices are in dismantle phase.
1196  */
1197 void dev_deactivate_many(struct list_head *head)
1198 {
1199         struct net_device *dev;
1200
1201         list_for_each_entry(dev, head, close_list) {
1202                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1203                                          &noop_qdisc);
1204                 if (dev_ingress_queue(dev))
1205                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
1206                                              &noop_qdisc);
1207
1208                 dev_watchdog_down(dev);
1209         }
1210
1211         /* Wait for outstanding qdisc-less dev_queue_xmit calls or
1212          * outstanding qdisc enqueuing calls.
1213          * This is avoided if all devices are in dismantle phase :
1214          * Caller will call synchronize_net() for us
1215          */
1216         synchronize_net();
1217
1218         list_for_each_entry(dev, head, close_list) {
1219                 netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);
1220
1221                 if (dev_ingress_queue(dev))
1222                         dev_reset_queue(dev, dev_ingress_queue(dev), NULL);
1223         }
1224
1225         /* Wait for outstanding qdisc_run calls. */
1226         list_for_each_entry(dev, head, close_list) {
1227                 while (some_qdisc_is_busy(dev))
1228                         yield();
1229                 /* The new qdisc is assigned at this point so we can safely
1230                  * unwind stale skb lists and qdisc statistics
1231                  */
1232                 netdev_for_each_tx_queue(dev, dev_qdisc_reset, NULL);
1233                 if (dev_ingress_queue(dev))
1234                         dev_qdisc_reset(dev, dev_ingress_queue(dev), NULL);
1235         }
1236 }
1237
1238 void dev_deactivate(struct net_device *dev)
1239 {
1240         LIST_HEAD(single);
1241
1242         list_add(&dev->close_list, &single);
1243         dev_deactivate_many(&single);
1244         list_del(&single);
1245 }
1246 EXPORT_SYMBOL(dev_deactivate);
1247
1248 static int qdisc_change_tx_queue_len(struct net_device *dev,
1249                                      struct netdev_queue *dev_queue)
1250 {
1251         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1252         const struct Qdisc_ops *ops = qdisc->ops;
1253
1254         if (ops->change_tx_queue_len)
1255                 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1256         return 0;
1257 }
1258
1259 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1260 {
1261         bool up = dev->flags & IFF_UP;
1262         unsigned int i;
1263         int ret = 0;
1264
1265         if (up)
1266                 dev_deactivate(dev);
1267
1268         for (i = 0; i < dev->num_tx_queues; i++) {
1269                 ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1270
1271                 /* TODO: revert changes on a partial failure */
1272                 if (ret)
1273                         break;
1274         }
1275
1276         if (up)
1277                 dev_activate(dev);
1278         return ret;
1279 }
1280
1281 static void dev_init_scheduler_queue(struct net_device *dev,
1282                                      struct netdev_queue *dev_queue,
1283                                      void *_qdisc)
1284 {
1285         struct Qdisc *qdisc = _qdisc;
1286
1287         rcu_assign_pointer(dev_queue->qdisc, qdisc);
1288         dev_queue->qdisc_sleeping = qdisc;
1289 }
1290
1291 void dev_init_scheduler(struct net_device *dev)
1292 {
1293         dev->qdisc = &noop_qdisc;
1294         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1295         if (dev_ingress_queue(dev))
1296                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1297
1298         timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1299 }
1300
1301 static void shutdown_scheduler_queue(struct net_device *dev,
1302                                      struct netdev_queue *dev_queue,
1303                                      void *_qdisc_default)
1304 {
1305         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1306         struct Qdisc *qdisc_default = _qdisc_default;
1307
1308         if (qdisc) {
1309                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1310                 dev_queue->qdisc_sleeping = qdisc_default;
1311
1312                 qdisc_destroy(qdisc);
1313         }
1314 }
1315
1316 void dev_shutdown(struct net_device *dev)
1317 {
1318         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1319         if (dev_ingress_queue(dev))
1320                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1321         qdisc_destroy(dev->qdisc);
1322         dev->qdisc = &noop_qdisc;
1323
1324         WARN_ON(timer_pending(&dev->watchdog_timer));
1325 }
1326
1327 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1328                                const struct tc_ratespec *conf,
1329                                u64 rate64)
1330 {
1331         memset(r, 0, sizeof(*r));
1332         r->overhead = conf->overhead;
1333         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1334         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1335         r->mult = 1;
1336         /*
1337          * The deal here is to replace a divide by a reciprocal one
1338          * in fast path (a reciprocal divide is a multiply and a shift)
1339          *
1340          * Normal formula would be :
1341          *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1342          *
1343          * We compute mult/shift to use instead :
1344          *  time_in_ns = (len * mult) >> shift;
1345          *
1346          * We try to get the highest possible mult value for accuracy,
1347          * but have to make sure no overflows will ever happen.
1348          */
1349         if (r->rate_bytes_ps > 0) {
1350                 u64 factor = NSEC_PER_SEC;
1351
1352                 for (;;) {
1353                         r->mult = div64_u64(factor, r->rate_bytes_ps);
1354                         if (r->mult & (1U << 31) || factor & (1ULL << 63))
1355                                 break;
1356                         factor <<= 1;
1357                         r->shift++;
1358                 }
1359         }
1360 }
1361 EXPORT_SYMBOL(psched_ratecfg_precompute);
1362
1363 static void mini_qdisc_rcu_func(struct rcu_head *head)
1364 {
1365 }
1366
1367 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1368                           struct tcf_proto *tp_head)
1369 {
1370         struct mini_Qdisc *miniq_old = rtnl_dereference(*miniqp->p_miniq);
1371         struct mini_Qdisc *miniq;
1372
1373         if (!tp_head) {
1374                 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1375                 /* Wait for flying RCU callback before it is freed. */
1376                 rcu_barrier_bh();
1377                 return;
1378         }
1379
1380         miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
1381                 &miniqp->miniq1 : &miniqp->miniq2;
1382
1383         /* We need to make sure that readers won't see the miniq
1384          * we are about to modify. So wait until previous call_rcu_bh callback
1385          * is done.
1386          */
1387         rcu_barrier_bh();
1388         miniq->filter_list = tp_head;
1389         rcu_assign_pointer(*miniqp->p_miniq, miniq);
1390
1391         if (miniq_old)
1392                 /* This is counterpart of the rcu barriers above. We need to
1393                  * block potential new user of miniq_old until all readers
1394                  * are not seeing it.
1395                  */
1396                 call_rcu_bh(&miniq_old->rcu, mini_qdisc_rcu_func);
1397 }
1398 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1399
1400 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1401                           struct mini_Qdisc __rcu **p_miniq)
1402 {
1403         miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1404         miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1405         miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1406         miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1407         miniqp->p_miniq = p_miniq;
1408 }
1409 EXPORT_SYMBOL(mini_qdisc_pair_init);