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Linux/net/sched/sch_generic.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * net/sched/sch_generic.c      Generic packet scheduler routines.
  4  *
  5  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  6  *              Jamal Hadi Salim, <hadi@cyberus.ca> 990601
  7  *              - Ingress support
  8  */
  9 
 10 #include <linux/bitops.h>
 11 #include <linux/module.h>
 12 #include <linux/types.h>
 13 #include <linux/kernel.h>
 14 #include <linux/sched.h>
 15 #include <linux/string.h>
 16 #include <linux/errno.h>
 17 #include <linux/netdevice.h>
 18 #include <linux/skbuff.h>
 19 #include <linux/rtnetlink.h>
 20 #include <linux/init.h>
 21 #include <linux/rcupdate.h>
 22 #include <linux/list.h>
 23 #include <linux/slab.h>
 24 #include <linux/if_vlan.h>
 25 #include <linux/skb_array.h>
 26 #include <linux/if_macvlan.h>
 27 #include <net/sch_generic.h>
 28 #include <net/pkt_sched.h>
 29 #include <net/dst.h>
 30 #include <trace/events/qdisc.h>
 31 #include <trace/events/net.h>
 32 #include <net/xfrm.h>
 33 
 34 /* Qdisc to use by default */
 35 const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
 36 EXPORT_SYMBOL(default_qdisc_ops);
 37 
 38 static void qdisc_maybe_clear_missed(struct Qdisc *q,
 39                                      const struct netdev_queue *txq)
 40 {
 41         clear_bit(__QDISC_STATE_MISSED, &q->state);
 42 
 43         /* Make sure the below netif_xmit_frozen_or_stopped()
 44          * checking happens after clearing STATE_MISSED.
 45          */
 46         smp_mb__after_atomic();
 47 
 48         /* Checking netif_xmit_frozen_or_stopped() again to
 49          * make sure STATE_MISSED is set if the STATE_MISSED
 50          * set by netif_tx_wake_queue()'s rescheduling of
 51          * net_tx_action() is cleared by the above clear_bit().
 52          */
 53         if (!netif_xmit_frozen_or_stopped(txq))
 54                 set_bit(__QDISC_STATE_MISSED, &q->state);
 55 }
 56 
 57 /* Main transmission queue. */
 58 
 59 /* Modifications to data participating in scheduling must be protected with
 60  * qdisc_lock(qdisc) spinlock.
 61  *
 62  * The idea is the following:
 63  * - enqueue, dequeue are serialized via qdisc root lock
 64  * - ingress filtering is also serialized via qdisc root lock
 65  * - updates to tree and tree walking are only done under the rtnl mutex.
 66  */
 67 
 68 #define SKB_XOFF_MAGIC ((struct sk_buff *)1UL)
 69 
 70 static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
 71 {
 72         const struct netdev_queue *txq = q->dev_queue;
 73         spinlock_t *lock = NULL;
 74         struct sk_buff *skb;
 75 
 76         if (q->flags & TCQ_F_NOLOCK) {
 77                 lock = qdisc_lock(q);
 78                 spin_lock(lock);
 79         }
 80 
 81         skb = skb_peek(&q->skb_bad_txq);
 82         if (skb) {
 83                 /* check the reason of requeuing without tx lock first */
 84                 txq = skb_get_tx_queue(txq->dev, skb);
 85                 if (!netif_xmit_frozen_or_stopped(txq)) {
 86                         skb = __skb_dequeue(&q->skb_bad_txq);
 87                         if (qdisc_is_percpu_stats(q)) {
 88                                 qdisc_qstats_cpu_backlog_dec(q, skb);
 89                                 qdisc_qstats_cpu_qlen_dec(q);
 90                         } else {
 91                                 qdisc_qstats_backlog_dec(q, skb);
 92                                 q->q.qlen--;
 93                         }
 94                 } else {
 95                         skb = SKB_XOFF_MAGIC;
 96                         qdisc_maybe_clear_missed(q, txq);
 97                 }
 98         }
 99 
100         if (lock)
101                 spin_unlock(lock);
102 
103         return skb;
104 }
105 
106 static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
107 {
108         struct sk_buff *skb = skb_peek(&q->skb_bad_txq);
109 
110         if (unlikely(skb))
111                 skb = __skb_dequeue_bad_txq(q);
112 
113         return skb;
114 }
115 
116 static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
117                                              struct sk_buff *skb)
118 {
119         spinlock_t *lock = NULL;
120 
121         if (q->flags & TCQ_F_NOLOCK) {
122                 lock = qdisc_lock(q);
123                 spin_lock(lock);
124         }
125 
126         __skb_queue_tail(&q->skb_bad_txq, skb);
127 
128         if (qdisc_is_percpu_stats(q)) {
129                 qdisc_qstats_cpu_backlog_inc(q, skb);
130                 qdisc_qstats_cpu_qlen_inc(q);
131         } else {
132                 qdisc_qstats_backlog_inc(q, skb);
133                 q->q.qlen++;
134         }
135 
136         if (lock)
137                 spin_unlock(lock);
138 }
139 
140 static inline void dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
141 {
142         spinlock_t *lock = NULL;
143 
144         if (q->flags & TCQ_F_NOLOCK) {
145                 lock = qdisc_lock(q);
146                 spin_lock(lock);
147         }
148 
149         while (skb) {
150                 struct sk_buff *next = skb->next;
151 
152                 __skb_queue_tail(&q->gso_skb, skb);
153 
154                 /* it's still part of the queue */
155                 if (qdisc_is_percpu_stats(q)) {
156                         qdisc_qstats_cpu_requeues_inc(q);
157                         qdisc_qstats_cpu_backlog_inc(q, skb);
158                         qdisc_qstats_cpu_qlen_inc(q);
159                 } else {
160                         q->qstats.requeues++;
161                         qdisc_qstats_backlog_inc(q, skb);
162                         q->q.qlen++;
163                 }
164 
165                 skb = next;
166         }
167         if (lock)
168                 spin_unlock(lock);
169         __netif_schedule(q);
170 }
171 
172 static void try_bulk_dequeue_skb(struct Qdisc *q,
173                                  struct sk_buff *skb,
174                                  const struct netdev_queue *txq,
175                                  int *packets)
176 {
177         int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
178 
179         while (bytelimit > 0) {
180                 struct sk_buff *nskb = q->dequeue(q);
181 
182                 if (!nskb)
183                         break;
184 
185                 bytelimit -= nskb->len; /* covers GSO len */
186                 skb->next = nskb;
187                 skb = nskb;
188                 (*packets)++; /* GSO counts as one pkt */
189         }
190         skb_mark_not_on_list(skb);
191 }
192 
193 /* This variant of try_bulk_dequeue_skb() makes sure
194  * all skbs in the chain are for the same txq
195  */
196 static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
197                                       struct sk_buff *skb,
198                                       int *packets)
199 {
200         int mapping = skb_get_queue_mapping(skb);
201         struct sk_buff *nskb;
202         int cnt = 0;
203 
204         do {
205                 nskb = q->dequeue(q);
206                 if (!nskb)
207                         break;
208                 if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
209                         qdisc_enqueue_skb_bad_txq(q, nskb);
210                         break;
211                 }
212                 skb->next = nskb;
213                 skb = nskb;
214         } while (++cnt < 8);
215         (*packets) += cnt;
216         skb_mark_not_on_list(skb);
217 }
218 
219 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
220  * A requeued skb (via q->gso_skb) can also be a SKB list.
221  */
222 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
223                                    int *packets)
224 {
225         const struct netdev_queue *txq = q->dev_queue;
226         struct sk_buff *skb = NULL;
227 
228         *packets = 1;
229         if (unlikely(!skb_queue_empty(&q->gso_skb))) {
230                 spinlock_t *lock = NULL;
231 
232                 if (q->flags & TCQ_F_NOLOCK) {
233                         lock = qdisc_lock(q);
234                         spin_lock(lock);
235                 }
236 
237                 skb = skb_peek(&q->gso_skb);
238 
239                 /* skb may be null if another cpu pulls gso_skb off in between
240                  * empty check and lock.
241                  */
242                 if (!skb) {
243                         if (lock)
244                                 spin_unlock(lock);
245                         goto validate;
246                 }
247 
248                 /* skb in gso_skb were already validated */
249                 *validate = false;
250                 if (xfrm_offload(skb))
251                         *validate = true;
252                 /* check the reason of requeuing without tx lock first */
253                 txq = skb_get_tx_queue(txq->dev, skb);
254                 if (!netif_xmit_frozen_or_stopped(txq)) {
255                         skb = __skb_dequeue(&q->gso_skb);
256                         if (qdisc_is_percpu_stats(q)) {
257                                 qdisc_qstats_cpu_backlog_dec(q, skb);
258                                 qdisc_qstats_cpu_qlen_dec(q);
259                         } else {
260                                 qdisc_qstats_backlog_dec(q, skb);
261                                 q->q.qlen--;
262                         }
263                 } else {
264                         skb = NULL;
265                         qdisc_maybe_clear_missed(q, txq);
266                 }
267                 if (lock)
268                         spin_unlock(lock);
269                 goto trace;
270         }
271 validate:
272         *validate = true;
273 
274         if ((q->flags & TCQ_F_ONETXQUEUE) &&
275             netif_xmit_frozen_or_stopped(txq)) {
276                 qdisc_maybe_clear_missed(q, txq);
277                 return skb;
278         }
279 
280         skb = qdisc_dequeue_skb_bad_txq(q);
281         if (unlikely(skb)) {
282                 if (skb == SKB_XOFF_MAGIC)
283                         return NULL;
284                 goto bulk;
285         }
286         skb = q->dequeue(q);
287         if (skb) {
288 bulk:
289                 if (qdisc_may_bulk(q))
290                         try_bulk_dequeue_skb(q, skb, txq, packets);
291                 else
292                         try_bulk_dequeue_skb_slow(q, skb, packets);
293         }
294 trace:
295         trace_qdisc_dequeue(q, txq, *packets, skb);
296         return skb;
297 }
298 
299 /*
300  * Transmit possibly several skbs, and handle the return status as
301  * required. Owning running seqcount bit guarantees that
302  * only one CPU can execute this function.
303  *
304  * Returns to the caller:
305  *                              false  - hardware queue frozen backoff
306  *                              true   - feel free to send more pkts
307  */
308 bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
309                      struct net_device *dev, struct netdev_queue *txq,
310                      spinlock_t *root_lock, bool validate)
311 {
312         int ret = NETDEV_TX_BUSY;
313         bool again = false;
314 
315         /* And release qdisc */
316         if (root_lock)
317                 spin_unlock(root_lock);
318 
319         /* Note that we validate skb (GSO, checksum, ...) outside of locks */
320         if (validate)
321                 skb = validate_xmit_skb_list(skb, dev, &again);
322 
323 #ifdef CONFIG_XFRM_OFFLOAD
324         if (unlikely(again)) {
325                 if (root_lock)
326                         spin_lock(root_lock);
327 
328                 dev_requeue_skb(skb, q);
329                 return false;
330         }
331 #endif
332 
333         if (likely(skb)) {
334                 HARD_TX_LOCK(dev, txq, smp_processor_id());
335                 if (!netif_xmit_frozen_or_stopped(txq))
336                         skb = dev_hard_start_xmit(skb, dev, txq, &ret);
337                 else
338                         qdisc_maybe_clear_missed(q, txq);
339 
340                 HARD_TX_UNLOCK(dev, txq);
341         } else {
342                 if (root_lock)
343                         spin_lock(root_lock);
344                 return true;
345         }
346 
347         if (root_lock)
348                 spin_lock(root_lock);
349 
350         if (!dev_xmit_complete(ret)) {
351                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
352                 if (unlikely(ret != NETDEV_TX_BUSY))
353                         net_warn_ratelimited("BUG %s code %d qlen %d\n",
354                                              dev->name, ret, q->q.qlen);
355 
356                 dev_requeue_skb(skb, q);
357                 return false;
358         }
359 
360         return true;
361 }
362 
363 /*
364  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
365  *
366  * running seqcount guarantees only one CPU can process
367  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
368  * this queue.
369  *
370  *  netif_tx_lock serializes accesses to device driver.
371  *
372  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
373  *  if one is grabbed, another must be free.
374  *
375  * Note, that this procedure can be called by a watchdog timer
376  *
377  * Returns to the caller:
378  *                              0  - queue is empty or throttled.
379  *                              >0 - queue is not empty.
380  *
381  */
382 static inline bool qdisc_restart(struct Qdisc *q, int *packets)
383 {
384         spinlock_t *root_lock = NULL;
385         struct netdev_queue *txq;
386         struct net_device *dev;
387         struct sk_buff *skb;
388         bool validate;
389 
390         /* Dequeue packet */
391         skb = dequeue_skb(q, &validate, packets);
392         if (unlikely(!skb))
393                 return false;
394 
395         if (!(q->flags & TCQ_F_NOLOCK))
396                 root_lock = qdisc_lock(q);
397 
398         dev = qdisc_dev(q);
399         txq = skb_get_tx_queue(dev, skb);
400 
401         return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
402 }
403 
404 void __qdisc_run(struct Qdisc *q)
405 {
406         int quota = dev_tx_weight;
407         int packets;
408 
409         while (qdisc_restart(q, &packets)) {
410                 quota -= packets;
411                 if (quota <= 0) {
412                         __netif_schedule(q);
413                         break;
414                 }
415         }
416 }
417 
418 unsigned long dev_trans_start(struct net_device *dev)
419 {
420         unsigned long val, res;
421         unsigned int i;
422 
423         if (is_vlan_dev(dev))
424                 dev = vlan_dev_real_dev(dev);
425         else if (netif_is_macvlan(dev))
426                 dev = macvlan_dev_real_dev(dev);
427         res = netdev_get_tx_queue(dev, 0)->trans_start;
428         for (i = 1; i < dev->num_tx_queues; i++) {
429                 val = netdev_get_tx_queue(dev, i)->trans_start;
430                 if (val && time_after(val, res))
431                         res = val;
432         }
433 
434         return res;
435 }
436 EXPORT_SYMBOL(dev_trans_start);
437 
438 static void dev_watchdog(struct timer_list *t)
439 {
440         struct net_device *dev = from_timer(dev, t, watchdog_timer);
441 
442         netif_tx_lock(dev);
443         if (!qdisc_tx_is_noop(dev)) {
444                 if (netif_device_present(dev) &&
445                     netif_running(dev) &&
446                     netif_carrier_ok(dev)) {
447                         int some_queue_timedout = 0;
448                         unsigned int i;
449                         unsigned long trans_start;
450 
451                         for (i = 0; i < dev->num_tx_queues; i++) {
452                                 struct netdev_queue *txq;
453 
454                                 txq = netdev_get_tx_queue(dev, i);
455                                 trans_start = txq->trans_start;
456                                 if (netif_xmit_stopped(txq) &&
457                                     time_after(jiffies, (trans_start +
458                                                          dev->watchdog_timeo))) {
459                                         some_queue_timedout = 1;
460                                         txq->trans_timeout++;
461                                         break;
462                                 }
463                         }
464 
465                         if (some_queue_timedout) {
466                                 trace_net_dev_xmit_timeout(dev, i);
467                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
468                                        dev->name, netdev_drivername(dev), i);
469                                 dev->netdev_ops->ndo_tx_timeout(dev, i);
470                         }
471                         if (!mod_timer(&dev->watchdog_timer,
472                                        round_jiffies(jiffies +
473                                                      dev->watchdog_timeo)))
474                                 dev_hold(dev);
475                 }
476         }
477         netif_tx_unlock(dev);
478 
479         dev_put(dev);
480 }
481 
482 void __netdev_watchdog_up(struct net_device *dev)
483 {
484         if (dev->netdev_ops->ndo_tx_timeout) {
485                 if (dev->watchdog_timeo <= 0)
486                         dev->watchdog_timeo = 5*HZ;
487                 if (!mod_timer(&dev->watchdog_timer,
488                                round_jiffies(jiffies + dev->watchdog_timeo)))
489                         dev_hold(dev);
490         }
491 }
492 EXPORT_SYMBOL_GPL(__netdev_watchdog_up);
493 
494 static void dev_watchdog_up(struct net_device *dev)
495 {
496         __netdev_watchdog_up(dev);
497 }
498 
499 static void dev_watchdog_down(struct net_device *dev)
500 {
501         netif_tx_lock_bh(dev);
502         if (del_timer(&dev->watchdog_timer))
503                 dev_put(dev);
504         netif_tx_unlock_bh(dev);
505 }
506 
507 /**
508  *      netif_carrier_on - set carrier
509  *      @dev: network device
510  *
511  * Device has detected acquisition of carrier.
512  */
513 void netif_carrier_on(struct net_device *dev)
514 {
515         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
516                 if (dev->reg_state == NETREG_UNINITIALIZED)
517                         return;
518                 atomic_inc(&dev->carrier_up_count);
519                 linkwatch_fire_event(dev);
520                 if (netif_running(dev))
521                         __netdev_watchdog_up(dev);
522         }
523 }
524 EXPORT_SYMBOL(netif_carrier_on);
525 
526 /**
527  *      netif_carrier_off - clear carrier
528  *      @dev: network device
529  *
530  * Device has detected loss of carrier.
531  */
532 void netif_carrier_off(struct net_device *dev)
533 {
534         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
535                 if (dev->reg_state == NETREG_UNINITIALIZED)
536                         return;
537                 atomic_inc(&dev->carrier_down_count);
538                 linkwatch_fire_event(dev);
539         }
540 }
541 EXPORT_SYMBOL(netif_carrier_off);
542 
543 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
544    under all circumstances. It is difficult to invent anything faster or
545    cheaper.
546  */
547 
548 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
549                         struct sk_buff **to_free)
550 {
551         __qdisc_drop(skb, to_free);
552         return NET_XMIT_CN;
553 }
554 
555 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
556 {
557         return NULL;
558 }
559 
560 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
561         .id             =       "noop",
562         .priv_size      =       0,
563         .enqueue        =       noop_enqueue,
564         .dequeue        =       noop_dequeue,
565         .peek           =       noop_dequeue,
566         .owner          =       THIS_MODULE,
567 };
568 
569 static struct netdev_queue noop_netdev_queue = {
570         RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
571         .qdisc_sleeping =       &noop_qdisc,
572 };
573 
574 struct Qdisc noop_qdisc = {
575         .enqueue        =       noop_enqueue,
576         .dequeue        =       noop_dequeue,
577         .flags          =       TCQ_F_BUILTIN,
578         .ops            =       &noop_qdisc_ops,
579         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
580         .dev_queue      =       &noop_netdev_queue,
581         .running        =       SEQCNT_ZERO(noop_qdisc.running),
582         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
583         .gso_skb = {
584                 .next = (struct sk_buff *)&noop_qdisc.gso_skb,
585                 .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
586                 .qlen = 0,
587                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
588         },
589         .skb_bad_txq = {
590                 .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
591                 .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
592                 .qlen = 0,
593                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
594         },
595 };
596 EXPORT_SYMBOL(noop_qdisc);
597 
598 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
599                         struct netlink_ext_ack *extack)
600 {
601         /* register_qdisc() assigns a default of noop_enqueue if unset,
602          * but __dev_queue_xmit() treats noqueue only as such
603          * if this is NULL - so clear it here. */
604         qdisc->enqueue = NULL;
605         return 0;
606 }
607 
608 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
609         .id             =       "noqueue",
610         .priv_size      =       0,
611         .init           =       noqueue_init,
612         .enqueue        =       noop_enqueue,
613         .dequeue        =       noop_dequeue,
614         .peek           =       noop_dequeue,
615         .owner          =       THIS_MODULE,
616 };
617 
618 static const u8 prio2band[TC_PRIO_MAX + 1] = {
619         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
620 };
621 
622 /* 3-band FIFO queue: old style, but should be a bit faster than
623    generic prio+fifo combination.
624  */
625 
626 #define PFIFO_FAST_BANDS 3
627 
628 /*
629  * Private data for a pfifo_fast scheduler containing:
630  *      - rings for priority bands
631  */
632 struct pfifo_fast_priv {
633         struct skb_array q[PFIFO_FAST_BANDS];
634 };
635 
636 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
637                                           int band)
638 {
639         return &priv->q[band];
640 }
641 
642 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
643                               struct sk_buff **to_free)
644 {
645         int band = prio2band[skb->priority & TC_PRIO_MAX];
646         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
647         struct skb_array *q = band2list(priv, band);
648         unsigned int pkt_len = qdisc_pkt_len(skb);
649         int err;
650 
651         err = skb_array_produce(q, skb);
652 
653         if (unlikely(err)) {
654                 if (qdisc_is_percpu_stats(qdisc))
655                         return qdisc_drop_cpu(skb, qdisc, to_free);
656                 else
657                         return qdisc_drop(skb, qdisc, to_free);
658         }
659 
660         qdisc_update_stats_at_enqueue(qdisc, pkt_len);
661         return NET_XMIT_SUCCESS;
662 }
663 
664 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
665 {
666         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
667         struct sk_buff *skb = NULL;
668         bool need_retry = true;
669         int band;
670 
671 retry:
672         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
673                 struct skb_array *q = band2list(priv, band);
674 
675                 if (__skb_array_empty(q))
676                         continue;
677 
678                 skb = __skb_array_consume(q);
679         }
680         if (likely(skb)) {
681                 qdisc_update_stats_at_dequeue(qdisc, skb);
682         } else if (need_retry &&
683                    test_bit(__QDISC_STATE_MISSED, &qdisc->state)) {
684                 /* Delay clearing the STATE_MISSED here to reduce
685                  * the overhead of the second spin_trylock() in
686                  * qdisc_run_begin() and __netif_schedule() calling
687                  * in qdisc_run_end().
688                  */
689                 clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
690 
691                 /* Make sure dequeuing happens after clearing
692                  * STATE_MISSED.
693                  */
694                 smp_mb__after_atomic();
695 
696                 need_retry = false;
697 
698                 goto retry;
699         } else {
700                 WRITE_ONCE(qdisc->empty, true);
701         }
702 
703         return skb;
704 }
705 
706 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
707 {
708         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
709         struct sk_buff *skb = NULL;
710         int band;
711 
712         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
713                 struct skb_array *q = band2list(priv, band);
714 
715                 skb = __skb_array_peek(q);
716         }
717 
718         return skb;
719 }
720 
721 static void pfifo_fast_reset(struct Qdisc *qdisc)
722 {
723         int i, band;
724         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
725 
726         for (band = 0; band < PFIFO_FAST_BANDS; band++) {
727                 struct skb_array *q = band2list(priv, band);
728                 struct sk_buff *skb;
729 
730                 /* NULL ring is possible if destroy path is due to a failed
731                  * skb_array_init() in pfifo_fast_init() case.
732                  */
733                 if (!q->ring.queue)
734                         continue;
735 
736                 while ((skb = __skb_array_consume(q)) != NULL)
737                         kfree_skb(skb);
738         }
739 
740         if (qdisc_is_percpu_stats(qdisc)) {
741                 for_each_possible_cpu(i) {
742                         struct gnet_stats_queue *q;
743 
744                         q = per_cpu_ptr(qdisc->cpu_qstats, i);
745                         q->backlog = 0;
746                         q->qlen = 0;
747                 }
748         }
749 }
750 
751 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
752 {
753         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
754 
755         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
756         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
757                 goto nla_put_failure;
758         return skb->len;
759 
760 nla_put_failure:
761         return -1;
762 }
763 
764 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
765                            struct netlink_ext_ack *extack)
766 {
767         unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
768         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
769         int prio;
770 
771         /* guard against zero length rings */
772         if (!qlen)
773                 return -EINVAL;
774 
775         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
776                 struct skb_array *q = band2list(priv, prio);
777                 int err;
778 
779                 err = skb_array_init(q, qlen, GFP_KERNEL);
780                 if (err)
781                         return -ENOMEM;
782         }
783 
784         /* Can by-pass the queue discipline */
785         qdisc->flags |= TCQ_F_CAN_BYPASS;
786         return 0;
787 }
788 
789 static void pfifo_fast_destroy(struct Qdisc *sch)
790 {
791         struct pfifo_fast_priv *priv = qdisc_priv(sch);
792         int prio;
793 
794         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
795                 struct skb_array *q = band2list(priv, prio);
796 
797                 /* NULL ring is possible if destroy path is due to a failed
798                  * skb_array_init() in pfifo_fast_init() case.
799                  */
800                 if (!q->ring.queue)
801                         continue;
802                 /* Destroy ring but no need to kfree_skb because a call to
803                  * pfifo_fast_reset() has already done that work.
804                  */
805                 ptr_ring_cleanup(&q->ring, NULL);
806         }
807 }
808 
809 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
810                                           unsigned int new_len)
811 {
812         struct pfifo_fast_priv *priv = qdisc_priv(sch);
813         struct skb_array *bands[PFIFO_FAST_BANDS];
814         int prio;
815 
816         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
817                 struct skb_array *q = band2list(priv, prio);
818 
819                 bands[prio] = q;
820         }
821 
822         return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
823                                          GFP_KERNEL);
824 }
825 
826 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
827         .id             =       "pfifo_fast",
828         .priv_size      =       sizeof(struct pfifo_fast_priv),
829         .enqueue        =       pfifo_fast_enqueue,
830         .dequeue        =       pfifo_fast_dequeue,
831         .peek           =       pfifo_fast_peek,
832         .init           =       pfifo_fast_init,
833         .destroy        =       pfifo_fast_destroy,
834         .reset          =       pfifo_fast_reset,
835         .dump           =       pfifo_fast_dump,
836         .change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
837         .owner          =       THIS_MODULE,
838         .static_flags   =       TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
839 };
840 EXPORT_SYMBOL(pfifo_fast_ops);
841 
842 static struct lock_class_key qdisc_tx_busylock;
843 static struct lock_class_key qdisc_running_key;
844 
845 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
846                           const struct Qdisc_ops *ops,
847                           struct netlink_ext_ack *extack)
848 {
849         struct Qdisc *sch;
850         unsigned int size = sizeof(*sch) + ops->priv_size;
851         int err = -ENOBUFS;
852         struct net_device *dev;
853 
854         if (!dev_queue) {
855                 NL_SET_ERR_MSG(extack, "No device queue given");
856                 err = -EINVAL;
857                 goto errout;
858         }
859 
860         dev = dev_queue->dev;
861         sch = kzalloc_node(size, GFP_KERNEL, netdev_queue_numa_node_read(dev_queue));
862 
863         if (!sch)
864                 goto errout;
865         __skb_queue_head_init(&sch->gso_skb);
866         __skb_queue_head_init(&sch->skb_bad_txq);
867         qdisc_skb_head_init(&sch->q);
868         spin_lock_init(&sch->q.lock);
869 
870         if (ops->static_flags & TCQ_F_CPUSTATS) {
871                 sch->cpu_bstats =
872                         netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
873                 if (!sch->cpu_bstats)
874                         goto errout1;
875 
876                 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
877                 if (!sch->cpu_qstats) {
878                         free_percpu(sch->cpu_bstats);
879                         goto errout1;
880                 }
881         }
882 
883         spin_lock_init(&sch->busylock);
884         lockdep_set_class(&sch->busylock,
885                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
886 
887         /* seqlock has the same scope of busylock, for NOLOCK qdisc */
888         spin_lock_init(&sch->seqlock);
889         lockdep_set_class(&sch->seqlock,
890                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
891 
892         seqcount_init(&sch->running);
893         lockdep_set_class(&sch->running,
894                           dev->qdisc_running_key ?: &qdisc_running_key);
895 
896         sch->ops = ops;
897         sch->flags = ops->static_flags;
898         sch->enqueue = ops->enqueue;
899         sch->dequeue = ops->dequeue;
900         sch->dev_queue = dev_queue;
901         sch->empty = true;
902         dev_hold(dev);
903         refcount_set(&sch->refcnt, 1);
904 
905         return sch;
906 errout1:
907         kfree(sch);
908 errout:
909         return ERR_PTR(err);
910 }
911 
912 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
913                                 const struct Qdisc_ops *ops,
914                                 unsigned int parentid,
915                                 struct netlink_ext_ack *extack)
916 {
917         struct Qdisc *sch;
918 
919         if (!try_module_get(ops->owner)) {
920                 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
921                 return NULL;
922         }
923 
924         sch = qdisc_alloc(dev_queue, ops, extack);
925         if (IS_ERR(sch)) {
926                 module_put(ops->owner);
927                 return NULL;
928         }
929         sch->parent = parentid;
930 
931         if (!ops->init || ops->init(sch, NULL, extack) == 0) {
932                 trace_qdisc_create(ops, dev_queue->dev, parentid);
933                 return sch;
934         }
935 
936         qdisc_put(sch);
937         return NULL;
938 }
939 EXPORT_SYMBOL(qdisc_create_dflt);
940 
941 /* Under qdisc_lock(qdisc) and BH! */
942 
943 void qdisc_reset(struct Qdisc *qdisc)
944 {
945         const struct Qdisc_ops *ops = qdisc->ops;
946         struct sk_buff *skb, *tmp;
947 
948         trace_qdisc_reset(qdisc);
949 
950         if (ops->reset)
951                 ops->reset(qdisc);
952 
953         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
954                 __skb_unlink(skb, &qdisc->gso_skb);
955                 kfree_skb_list(skb);
956         }
957 
958         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
959                 __skb_unlink(skb, &qdisc->skb_bad_txq);
960                 kfree_skb_list(skb);
961         }
962 
963         qdisc->q.qlen = 0;
964         qdisc->qstats.backlog = 0;
965 }
966 EXPORT_SYMBOL(qdisc_reset);
967 
968 void qdisc_free(struct Qdisc *qdisc)
969 {
970         if (qdisc_is_percpu_stats(qdisc)) {
971                 free_percpu(qdisc->cpu_bstats);
972                 free_percpu(qdisc->cpu_qstats);
973         }
974 
975         kfree(qdisc);
976 }
977 
978 static void qdisc_free_cb(struct rcu_head *head)
979 {
980         struct Qdisc *q = container_of(head, struct Qdisc, rcu);
981 
982         qdisc_free(q);
983 }
984 
985 static void qdisc_destroy(struct Qdisc *qdisc)
986 {
987         const struct Qdisc_ops  *ops = qdisc->ops;
988 
989 #ifdef CONFIG_NET_SCHED
990         qdisc_hash_del(qdisc);
991 
992         qdisc_put_stab(rtnl_dereference(qdisc->stab));
993 #endif
994         gen_kill_estimator(&qdisc->rate_est);
995 
996         qdisc_reset(qdisc);
997 
998         if (ops->destroy)
999                 ops->destroy(qdisc);
1000 
1001         module_put(ops->owner);
1002         dev_put(qdisc_dev(qdisc));
1003 
1004         trace_qdisc_destroy(qdisc);
1005 
1006         call_rcu(&qdisc->rcu, qdisc_free_cb);
1007 }
1008 
1009 void qdisc_put(struct Qdisc *qdisc)
1010 {
1011         if (!qdisc)
1012                 return;
1013 
1014         if (qdisc->flags & TCQ_F_BUILTIN ||
1015             !refcount_dec_and_test(&qdisc->refcnt))
1016                 return;
1017 
1018         qdisc_destroy(qdisc);
1019 }
1020 EXPORT_SYMBOL(qdisc_put);
1021 
1022 /* Version of qdisc_put() that is called with rtnl mutex unlocked.
1023  * Intended to be used as optimization, this function only takes rtnl lock if
1024  * qdisc reference counter reached zero.
1025  */
1026 
1027 void qdisc_put_unlocked(struct Qdisc *qdisc)
1028 {
1029         if (qdisc->flags & TCQ_F_BUILTIN ||
1030             !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
1031                 return;
1032 
1033         qdisc_destroy(qdisc);
1034         rtnl_unlock();
1035 }
1036 EXPORT_SYMBOL(qdisc_put_unlocked);
1037 
1038 /* Attach toplevel qdisc to device queue. */
1039 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
1040                               struct Qdisc *qdisc)
1041 {
1042         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
1043         spinlock_t *root_lock;
1044 
1045         root_lock = qdisc_lock(oqdisc);
1046         spin_lock_bh(root_lock);
1047 
1048         /* ... and graft new one */
1049         if (qdisc == NULL)
1050                 qdisc = &noop_qdisc;
1051         dev_queue->qdisc_sleeping = qdisc;
1052         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1053 
1054         spin_unlock_bh(root_lock);
1055 
1056         return oqdisc;
1057 }
1058 EXPORT_SYMBOL(dev_graft_qdisc);
1059 
1060 static void attach_one_default_qdisc(struct net_device *dev,
1061                                      struct netdev_queue *dev_queue,
1062                                      void *_unused)
1063 {
1064         struct Qdisc *qdisc;
1065         const struct Qdisc_ops *ops = default_qdisc_ops;
1066 
1067         if (dev->priv_flags & IFF_NO_QUEUE)
1068                 ops = &noqueue_qdisc_ops;
1069         else if(dev->type == ARPHRD_CAN)
1070                 ops = &pfifo_fast_ops;
1071 
1072         qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1073         if (!qdisc)
1074                 return;
1075 
1076         if (!netif_is_multiqueue(dev))
1077                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1078         dev_queue->qdisc_sleeping = qdisc;
1079 }
1080 
1081 static void attach_default_qdiscs(struct net_device *dev)
1082 {
1083         struct netdev_queue *txq;
1084         struct Qdisc *qdisc;
1085 
1086         txq = netdev_get_tx_queue(dev, 0);
1087 
1088         if (!netif_is_multiqueue(dev) ||
1089             dev->priv_flags & IFF_NO_QUEUE) {
1090                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1091                 dev->qdisc = txq->qdisc_sleeping;
1092                 qdisc_refcount_inc(dev->qdisc);
1093         } else {
1094                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1095                 if (qdisc) {
1096                         dev->qdisc = qdisc;
1097                         qdisc->ops->attach(qdisc);
1098                 }
1099         }
1100 
1101         /* Detect default qdisc setup/init failed and fallback to "noqueue" */
1102         if (dev->qdisc == &noop_qdisc) {
1103                 netdev_warn(dev, "default qdisc (%s) fail, fallback to %s\n",
1104                             default_qdisc_ops->id, noqueue_qdisc_ops.id);
1105                 dev->priv_flags |= IFF_NO_QUEUE;
1106                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1107                 dev->qdisc = txq->qdisc_sleeping;
1108                 qdisc_refcount_inc(dev->qdisc);
1109                 dev->priv_flags ^= IFF_NO_QUEUE;
1110         }
1111 
1112 #ifdef CONFIG_NET_SCHED
1113         if (dev->qdisc != &noop_qdisc)
1114                 qdisc_hash_add(dev->qdisc, false);
1115 #endif
1116 }
1117 
1118 static void transition_one_qdisc(struct net_device *dev,
1119                                  struct netdev_queue *dev_queue,
1120                                  void *_need_watchdog)
1121 {
1122         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1123         int *need_watchdog_p = _need_watchdog;
1124 
1125         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1126                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1127 
1128         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1129         if (need_watchdog_p) {
1130                 dev_queue->trans_start = 0;
1131                 *need_watchdog_p = 1;
1132         }
1133 }
1134 
1135 void dev_activate(struct net_device *dev)
1136 {
1137         int need_watchdog;
1138 
1139         /* No queueing discipline is attached to device;
1140          * create default one for devices, which need queueing
1141          * and noqueue_qdisc for virtual interfaces
1142          */
1143 
1144         if (dev->qdisc == &noop_qdisc)
1145                 attach_default_qdiscs(dev);
1146 
1147         if (!netif_carrier_ok(dev))
1148                 /* Delay activation until next carrier-on event */
1149                 return;
1150 
1151         need_watchdog = 0;
1152         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1153         if (dev_ingress_queue(dev))
1154                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1155 
1156         if (need_watchdog) {
1157                 netif_trans_update(dev);
1158                 dev_watchdog_up(dev);
1159         }
1160 }
1161 EXPORT_SYMBOL(dev_activate);
1162 
1163 static void qdisc_deactivate(struct Qdisc *qdisc)
1164 {
1165         if (qdisc->flags & TCQ_F_BUILTIN)
1166                 return;
1167 
1168         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1169 }
1170 
1171 static void dev_deactivate_queue(struct net_device *dev,
1172                                  struct netdev_queue *dev_queue,
1173                                  void *_qdisc_default)
1174 {
1175         struct Qdisc *qdisc_default = _qdisc_default;
1176         struct Qdisc *qdisc;
1177 
1178         qdisc = rtnl_dereference(dev_queue->qdisc);
1179         if (qdisc) {
1180                 qdisc_deactivate(qdisc);
1181                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1182         }
1183 }
1184 
1185 static void dev_reset_queue(struct net_device *dev,
1186                             struct netdev_queue *dev_queue,
1187                             void *_unused)
1188 {
1189         struct Qdisc *qdisc;
1190         bool nolock;
1191 
1192         qdisc = dev_queue->qdisc_sleeping;
1193         if (!qdisc)
1194                 return;
1195 
1196         nolock = qdisc->flags & TCQ_F_NOLOCK;
1197 
1198         if (nolock)
1199                 spin_lock_bh(&qdisc->seqlock);
1200         spin_lock_bh(qdisc_lock(qdisc));
1201 
1202         qdisc_reset(qdisc);
1203 
1204         spin_unlock_bh(qdisc_lock(qdisc));
1205         if (nolock) {
1206                 clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
1207                 spin_unlock_bh(&qdisc->seqlock);
1208         }
1209 }
1210 
1211 static bool some_qdisc_is_busy(struct net_device *dev)
1212 {
1213         unsigned int i;
1214 
1215         for (i = 0; i < dev->num_tx_queues; i++) {
1216                 struct netdev_queue *dev_queue;
1217                 spinlock_t *root_lock;
1218                 struct Qdisc *q;
1219                 int val;
1220 
1221                 dev_queue = netdev_get_tx_queue(dev, i);
1222                 q = dev_queue->qdisc_sleeping;
1223 
1224                 root_lock = qdisc_lock(q);
1225                 spin_lock_bh(root_lock);
1226 
1227                 val = (qdisc_is_running(q) ||
1228                        test_bit(__QDISC_STATE_SCHED, &q->state));
1229 
1230                 spin_unlock_bh(root_lock);
1231 
1232                 if (val)
1233                         return true;
1234         }
1235         return false;
1236 }
1237 
1238 /**
1239  *      dev_deactivate_many - deactivate transmissions on several devices
1240  *      @head: list of devices to deactivate
1241  *
1242  *      This function returns only when all outstanding transmissions
1243  *      have completed, unless all devices are in dismantle phase.
1244  */
1245 void dev_deactivate_many(struct list_head *head)
1246 {
1247         struct net_device *dev;
1248 
1249         list_for_each_entry(dev, head, close_list) {
1250                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1251                                          &noop_qdisc);
1252                 if (dev_ingress_queue(dev))
1253                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
1254                                              &noop_qdisc);
1255 
1256                 dev_watchdog_down(dev);
1257         }
1258 
1259         /* Wait for outstanding qdisc-less dev_queue_xmit calls or
1260          * outstanding qdisc enqueuing calls.
1261          * This is avoided if all devices are in dismantle phase :
1262          * Caller will call synchronize_net() for us
1263          */
1264         synchronize_net();
1265 
1266         list_for_each_entry(dev, head, close_list) {
1267                 netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);
1268 
1269                 if (dev_ingress_queue(dev))
1270                         dev_reset_queue(dev, dev_ingress_queue(dev), NULL);
1271         }
1272 
1273         /* Wait for outstanding qdisc_run calls. */
1274         list_for_each_entry(dev, head, close_list) {
1275                 while (some_qdisc_is_busy(dev)) {
1276                         /* wait_event() would avoid this sleep-loop but would
1277                          * require expensive checks in the fast paths of packet
1278                          * processing which isn't worth it.
1279                          */
1280                         schedule_timeout_uninterruptible(1);
1281                 }
1282         }
1283 }
1284 
1285 void dev_deactivate(struct net_device *dev)
1286 {
1287         LIST_HEAD(single);
1288 
1289         list_add(&dev->close_list, &single);
1290         dev_deactivate_many(&single);
1291         list_del(&single);
1292 }
1293 EXPORT_SYMBOL(dev_deactivate);
1294 
1295 static int qdisc_change_tx_queue_len(struct net_device *dev,
1296                                      struct netdev_queue *dev_queue)
1297 {
1298         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1299         const struct Qdisc_ops *ops = qdisc->ops;
1300 
1301         if (ops->change_tx_queue_len)
1302                 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1303         return 0;
1304 }
1305 
1306 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1307 {
1308         bool up = dev->flags & IFF_UP;
1309         unsigned int i;
1310         int ret = 0;
1311 
1312         if (up)
1313                 dev_deactivate(dev);
1314 
1315         for (i = 0; i < dev->num_tx_queues; i++) {
1316                 ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1317 
1318                 /* TODO: revert changes on a partial failure */
1319                 if (ret)
1320                         break;
1321         }
1322 
1323         if (up)
1324                 dev_activate(dev);
1325         return ret;
1326 }
1327 
1328 static void dev_init_scheduler_queue(struct net_device *dev,
1329                                      struct netdev_queue *dev_queue,
1330                                      void *_qdisc)
1331 {
1332         struct Qdisc *qdisc = _qdisc;
1333 
1334         rcu_assign_pointer(dev_queue->qdisc, qdisc);
1335         dev_queue->qdisc_sleeping = qdisc;
1336 }
1337 
1338 void dev_init_scheduler(struct net_device *dev)
1339 {
1340         dev->qdisc = &noop_qdisc;
1341         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1342         if (dev_ingress_queue(dev))
1343                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1344 
1345         timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1346 }
1347 
1348 static void shutdown_scheduler_queue(struct net_device *dev,
1349                                      struct netdev_queue *dev_queue,
1350                                      void *_qdisc_default)
1351 {
1352         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1353         struct Qdisc *qdisc_default = _qdisc_default;
1354 
1355         if (qdisc) {
1356                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1357                 dev_queue->qdisc_sleeping = qdisc_default;
1358 
1359                 qdisc_put(qdisc);
1360         }
1361 }
1362 
1363 void dev_shutdown(struct net_device *dev)
1364 {
1365         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1366         if (dev_ingress_queue(dev))
1367                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1368         qdisc_put(dev->qdisc);
1369         dev->qdisc = &noop_qdisc;
1370 
1371         WARN_ON(timer_pending(&dev->watchdog_timer));
1372 }
1373 
1374 /**
1375  * psched_ratecfg_precompute__() - Pre-compute values for reciprocal division
1376  * @rate:   Rate to compute reciprocal division values of
1377  * @mult:   Multiplier for reciprocal division
1378  * @shift:  Shift for reciprocal division
1379  *
1380  * The multiplier and shift for reciprocal division by rate are stored
1381  * in mult and shift.
1382  *
1383  * The deal here is to replace a divide by a reciprocal one
1384  * in fast path (a reciprocal divide is a multiply and a shift)
1385  *
1386  * Normal formula would be :
1387  *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1388  *
1389  * We compute mult/shift to use instead :
1390  *  time_in_ns = (len * mult) >> shift;
1391  *
1392  * We try to get the highest possible mult value for accuracy,
1393  * but have to make sure no overflows will ever happen.
1394  *
1395  * reciprocal_value() is not used here it doesn't handle 64-bit values.
1396  */
1397 static void psched_ratecfg_precompute__(u64 rate, u32 *mult, u8 *shift)
1398 {
1399         u64 factor = NSEC_PER_SEC;
1400 
1401         *mult = 1;
1402         *shift = 0;
1403 
1404         if (rate <= 0)
1405                 return;
1406 
1407         for (;;) {
1408                 *mult = div64_u64(factor, rate);
1409                 if (*mult & (1U << 31) || factor & (1ULL << 63))
1410                         break;
1411                 factor <<= 1;
1412                 (*shift)++;
1413         }
1414 }
1415 
1416 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1417                                const struct tc_ratespec *conf,
1418                                u64 rate64)
1419 {
1420         memset(r, 0, sizeof(*r));
1421         r->overhead = conf->overhead;
1422         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1423         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1424         psched_ratecfg_precompute__(r->rate_bytes_ps, &r->mult, &r->shift);
1425 }
1426 EXPORT_SYMBOL(psched_ratecfg_precompute);
1427 
1428 void psched_ppscfg_precompute(struct psched_pktrate *r, u64 pktrate64)
1429 {
1430         r->rate_pkts_ps = pktrate64;
1431         psched_ratecfg_precompute__(r->rate_pkts_ps, &r->mult, &r->shift);
1432 }
1433 EXPORT_SYMBOL(psched_ppscfg_precompute);
1434 
1435 static void mini_qdisc_rcu_func(struct rcu_head *head)
1436 {
1437 }
1438 
1439 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1440                           struct tcf_proto *tp_head)
1441 {
1442         /* Protected with chain0->filter_chain_lock.
1443          * Can't access chain directly because tp_head can be NULL.
1444          */
1445         struct mini_Qdisc *miniq_old =
1446                 rcu_dereference_protected(*miniqp->p_miniq, 1);
1447         struct mini_Qdisc *miniq;
1448 
1449         if (!tp_head) {
1450                 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1451                 /* Wait for flying RCU callback before it is freed. */
1452                 rcu_barrier();
1453                 return;
1454         }
1455 
1456         miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
1457                 &miniqp->miniq1 : &miniqp->miniq2;
1458 
1459         /* We need to make sure that readers won't see the miniq
1460          * we are about to modify. So wait until previous call_rcu callback
1461          * is done.
1462          */
1463         rcu_barrier();
1464         miniq->filter_list = tp_head;
1465         rcu_assign_pointer(*miniqp->p_miniq, miniq);
1466 
1467         if (miniq_old)
1468                 /* This is counterpart of the rcu barriers above. We need to
1469                  * block potential new user of miniq_old until all readers
1470                  * are not seeing it.
1471                  */
1472                 call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func);
1473 }
1474 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1475 
1476 void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
1477                                 struct tcf_block *block)
1478 {
1479         miniqp->miniq1.block = block;
1480         miniqp->miniq2.block = block;
1481 }
1482 EXPORT_SYMBOL(mini_qdisc_pair_block_init);
1483 
1484 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1485                           struct mini_Qdisc __rcu **p_miniq)
1486 {
1487         miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1488         miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1489         miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1490         miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1491         miniqp->p_miniq = p_miniq;
1492 }
1493 EXPORT_SYMBOL(mini_qdisc_pair_init);
1494 

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