xref: /linux/net/sched/sch_generic.c (revision b77e0ce62d63a761ffb7f7245a215a49f5921c2f)
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 /* Main transmission queue. */
39 
40 /* Modifications to data participating in scheduling must be protected with
41  * qdisc_lock(qdisc) spinlock.
42  *
43  * The idea is the following:
44  * - enqueue, dequeue are serialized via qdisc root lock
45  * - ingress filtering is also serialized via qdisc root lock
46  * - updates to tree and tree walking are only done under the rtnl mutex.
47  */
48 
49 #define SKB_XOFF_MAGIC ((struct sk_buff *)1UL)
50 
51 static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
52 {
53 	const struct netdev_queue *txq = q->dev_queue;
54 	spinlock_t *lock = NULL;
55 	struct sk_buff *skb;
56 
57 	if (q->flags & TCQ_F_NOLOCK) {
58 		lock = qdisc_lock(q);
59 		spin_lock(lock);
60 	}
61 
62 	skb = skb_peek(&q->skb_bad_txq);
63 	if (skb) {
64 		/* check the reason of requeuing without tx lock first */
65 		txq = skb_get_tx_queue(txq->dev, skb);
66 		if (!netif_xmit_frozen_or_stopped(txq)) {
67 			skb = __skb_dequeue(&q->skb_bad_txq);
68 			if (qdisc_is_percpu_stats(q)) {
69 				qdisc_qstats_cpu_backlog_dec(q, skb);
70 				qdisc_qstats_cpu_qlen_dec(q);
71 			} else {
72 				qdisc_qstats_backlog_dec(q, skb);
73 				q->q.qlen--;
74 			}
75 		} else {
76 			skb = SKB_XOFF_MAGIC;
77 		}
78 	}
79 
80 	if (lock)
81 		spin_unlock(lock);
82 
83 	return skb;
84 }
85 
86 static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
87 {
88 	struct sk_buff *skb = skb_peek(&q->skb_bad_txq);
89 
90 	if (unlikely(skb))
91 		skb = __skb_dequeue_bad_txq(q);
92 
93 	return skb;
94 }
95 
96 static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
97 					     struct sk_buff *skb)
98 {
99 	spinlock_t *lock = NULL;
100 
101 	if (q->flags & TCQ_F_NOLOCK) {
102 		lock = qdisc_lock(q);
103 		spin_lock(lock);
104 	}
105 
106 	__skb_queue_tail(&q->skb_bad_txq, skb);
107 
108 	if (qdisc_is_percpu_stats(q)) {
109 		qdisc_qstats_cpu_backlog_inc(q, skb);
110 		qdisc_qstats_cpu_qlen_inc(q);
111 	} else {
112 		qdisc_qstats_backlog_inc(q, skb);
113 		q->q.qlen++;
114 	}
115 
116 	if (lock)
117 		spin_unlock(lock);
118 }
119 
120 static inline void dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
121 {
122 	spinlock_t *lock = NULL;
123 
124 	if (q->flags & TCQ_F_NOLOCK) {
125 		lock = qdisc_lock(q);
126 		spin_lock(lock);
127 	}
128 
129 	while (skb) {
130 		struct sk_buff *next = skb->next;
131 
132 		__skb_queue_tail(&q->gso_skb, skb);
133 
134 		/* it's still part of the queue */
135 		if (qdisc_is_percpu_stats(q)) {
136 			qdisc_qstats_cpu_requeues_inc(q);
137 			qdisc_qstats_cpu_backlog_inc(q, skb);
138 			qdisc_qstats_cpu_qlen_inc(q);
139 		} else {
140 			q->qstats.requeues++;
141 			qdisc_qstats_backlog_inc(q, skb);
142 			q->q.qlen++;
143 		}
144 
145 		skb = next;
146 	}
147 	if (lock)
148 		spin_unlock(lock);
149 	__netif_schedule(q);
150 }
151 
152 static void try_bulk_dequeue_skb(struct Qdisc *q,
153 				 struct sk_buff *skb,
154 				 const struct netdev_queue *txq,
155 				 int *packets)
156 {
157 	int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
158 
159 	while (bytelimit > 0) {
160 		struct sk_buff *nskb = q->dequeue(q);
161 
162 		if (!nskb)
163 			break;
164 
165 		bytelimit -= nskb->len; /* covers GSO len */
166 		skb->next = nskb;
167 		skb = nskb;
168 		(*packets)++; /* GSO counts as one pkt */
169 	}
170 	skb_mark_not_on_list(skb);
171 }
172 
173 /* This variant of try_bulk_dequeue_skb() makes sure
174  * all skbs in the chain are for the same txq
175  */
176 static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
177 				      struct sk_buff *skb,
178 				      int *packets)
179 {
180 	int mapping = skb_get_queue_mapping(skb);
181 	struct sk_buff *nskb;
182 	int cnt = 0;
183 
184 	do {
185 		nskb = q->dequeue(q);
186 		if (!nskb)
187 			break;
188 		if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
189 			qdisc_enqueue_skb_bad_txq(q, nskb);
190 			break;
191 		}
192 		skb->next = nskb;
193 		skb = nskb;
194 	} while (++cnt < 8);
195 	(*packets) += cnt;
196 	skb_mark_not_on_list(skb);
197 }
198 
199 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
200  * A requeued skb (via q->gso_skb) can also be a SKB list.
201  */
202 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
203 				   int *packets)
204 {
205 	const struct netdev_queue *txq = q->dev_queue;
206 	struct sk_buff *skb = NULL;
207 
208 	*packets = 1;
209 	if (unlikely(!skb_queue_empty(&q->gso_skb))) {
210 		spinlock_t *lock = NULL;
211 
212 		if (q->flags & TCQ_F_NOLOCK) {
213 			lock = qdisc_lock(q);
214 			spin_lock(lock);
215 		}
216 
217 		skb = skb_peek(&q->gso_skb);
218 
219 		/* skb may be null if another cpu pulls gso_skb off in between
220 		 * empty check and lock.
221 		 */
222 		if (!skb) {
223 			if (lock)
224 				spin_unlock(lock);
225 			goto validate;
226 		}
227 
228 		/* skb in gso_skb were already validated */
229 		*validate = false;
230 		if (xfrm_offload(skb))
231 			*validate = true;
232 		/* check the reason of requeuing without tx lock first */
233 		txq = skb_get_tx_queue(txq->dev, skb);
234 		if (!netif_xmit_frozen_or_stopped(txq)) {
235 			skb = __skb_dequeue(&q->gso_skb);
236 			if (qdisc_is_percpu_stats(q)) {
237 				qdisc_qstats_cpu_backlog_dec(q, skb);
238 				qdisc_qstats_cpu_qlen_dec(q);
239 			} else {
240 				qdisc_qstats_backlog_dec(q, skb);
241 				q->q.qlen--;
242 			}
243 		} else {
244 			skb = NULL;
245 		}
246 		if (lock)
247 			spin_unlock(lock);
248 		goto trace;
249 	}
250 validate:
251 	*validate = true;
252 
253 	if ((q->flags & TCQ_F_ONETXQUEUE) &&
254 	    netif_xmit_frozen_or_stopped(txq))
255 		return skb;
256 
257 	skb = qdisc_dequeue_skb_bad_txq(q);
258 	if (unlikely(skb)) {
259 		if (skb == SKB_XOFF_MAGIC)
260 			return NULL;
261 		goto bulk;
262 	}
263 	skb = q->dequeue(q);
264 	if (skb) {
265 bulk:
266 		if (qdisc_may_bulk(q))
267 			try_bulk_dequeue_skb(q, skb, txq, packets);
268 		else
269 			try_bulk_dequeue_skb_slow(q, skb, packets);
270 	}
271 trace:
272 	trace_qdisc_dequeue(q, txq, *packets, skb);
273 	return skb;
274 }
275 
276 /*
277  * Transmit possibly several skbs, and handle the return status as
278  * required. Owning running seqcount bit guarantees that
279  * only one CPU can execute this function.
280  *
281  * Returns to the caller:
282  *				false  - hardware queue frozen backoff
283  *				true   - feel free to send more pkts
284  */
285 bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
286 		     struct net_device *dev, struct netdev_queue *txq,
287 		     spinlock_t *root_lock, bool validate)
288 {
289 	int ret = NETDEV_TX_BUSY;
290 	bool again = false;
291 
292 	/* And release qdisc */
293 	if (root_lock)
294 		spin_unlock(root_lock);
295 
296 	/* Note that we validate skb (GSO, checksum, ...) outside of locks */
297 	if (validate)
298 		skb = validate_xmit_skb_list(skb, dev, &again);
299 
300 #ifdef CONFIG_XFRM_OFFLOAD
301 	if (unlikely(again)) {
302 		if (root_lock)
303 			spin_lock(root_lock);
304 
305 		dev_requeue_skb(skb, q);
306 		return false;
307 	}
308 #endif
309 
310 	if (likely(skb)) {
311 		HARD_TX_LOCK(dev, txq, smp_processor_id());
312 		if (!netif_xmit_frozen_or_stopped(txq))
313 			skb = dev_hard_start_xmit(skb, dev, txq, &ret);
314 
315 		HARD_TX_UNLOCK(dev, txq);
316 	} else {
317 		if (root_lock)
318 			spin_lock(root_lock);
319 		return true;
320 	}
321 
322 	if (root_lock)
323 		spin_lock(root_lock);
324 
325 	if (!dev_xmit_complete(ret)) {
326 		/* Driver returned NETDEV_TX_BUSY - requeue skb */
327 		if (unlikely(ret != NETDEV_TX_BUSY))
328 			net_warn_ratelimited("BUG %s code %d qlen %d\n",
329 					     dev->name, ret, q->q.qlen);
330 
331 		dev_requeue_skb(skb, q);
332 		return false;
333 	}
334 
335 	return true;
336 }
337 
338 /*
339  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
340  *
341  * running seqcount guarantees only one CPU can process
342  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
343  * this queue.
344  *
345  *  netif_tx_lock serializes accesses to device driver.
346  *
347  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
348  *  if one is grabbed, another must be free.
349  *
350  * Note, that this procedure can be called by a watchdog timer
351  *
352  * Returns to the caller:
353  *				0  - queue is empty or throttled.
354  *				>0 - queue is not empty.
355  *
356  */
357 static inline bool qdisc_restart(struct Qdisc *q, int *packets)
358 {
359 	spinlock_t *root_lock = NULL;
360 	struct netdev_queue *txq;
361 	struct net_device *dev;
362 	struct sk_buff *skb;
363 	bool validate;
364 
365 	/* Dequeue packet */
366 	skb = dequeue_skb(q, &validate, packets);
367 	if (unlikely(!skb))
368 		return false;
369 
370 	if (!(q->flags & TCQ_F_NOLOCK))
371 		root_lock = qdisc_lock(q);
372 
373 	dev = qdisc_dev(q);
374 	txq = skb_get_tx_queue(dev, skb);
375 
376 	return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
377 }
378 
379 void __qdisc_run(struct Qdisc *q)
380 {
381 	int quota = dev_tx_weight;
382 	int packets;
383 
384 	while (qdisc_restart(q, &packets)) {
385 		quota -= packets;
386 		if (quota <= 0) {
387 			__netif_schedule(q);
388 			break;
389 		}
390 	}
391 }
392 
393 unsigned long dev_trans_start(struct net_device *dev)
394 {
395 	unsigned long val, res;
396 	unsigned int i;
397 
398 	if (is_vlan_dev(dev))
399 		dev = vlan_dev_real_dev(dev);
400 	else if (netif_is_macvlan(dev))
401 		dev = macvlan_dev_real_dev(dev);
402 	res = netdev_get_tx_queue(dev, 0)->trans_start;
403 	for (i = 1; i < dev->num_tx_queues; i++) {
404 		val = netdev_get_tx_queue(dev, i)->trans_start;
405 		if (val && time_after(val, res))
406 			res = val;
407 	}
408 
409 	return res;
410 }
411 EXPORT_SYMBOL(dev_trans_start);
412 
413 static void dev_watchdog(struct timer_list *t)
414 {
415 	struct net_device *dev = from_timer(dev, t, watchdog_timer);
416 
417 	netif_tx_lock(dev);
418 	if (!qdisc_tx_is_noop(dev)) {
419 		if (netif_device_present(dev) &&
420 		    netif_running(dev) &&
421 		    netif_carrier_ok(dev)) {
422 			int some_queue_timedout = 0;
423 			unsigned int i;
424 			unsigned long trans_start;
425 
426 			for (i = 0; i < dev->num_tx_queues; i++) {
427 				struct netdev_queue *txq;
428 
429 				txq = netdev_get_tx_queue(dev, i);
430 				trans_start = txq->trans_start;
431 				if (netif_xmit_stopped(txq) &&
432 				    time_after(jiffies, (trans_start +
433 							 dev->watchdog_timeo))) {
434 					some_queue_timedout = 1;
435 					txq->trans_timeout++;
436 					break;
437 				}
438 			}
439 
440 			if (some_queue_timedout) {
441 				trace_net_dev_xmit_timeout(dev, i);
442 				WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
443 				       dev->name, netdev_drivername(dev), i);
444 				dev->netdev_ops->ndo_tx_timeout(dev, i);
445 			}
446 			if (!mod_timer(&dev->watchdog_timer,
447 				       round_jiffies(jiffies +
448 						     dev->watchdog_timeo)))
449 				dev_hold(dev);
450 		}
451 	}
452 	netif_tx_unlock(dev);
453 
454 	dev_put(dev);
455 }
456 
457 void __netdev_watchdog_up(struct net_device *dev)
458 {
459 	if (dev->netdev_ops->ndo_tx_timeout) {
460 		if (dev->watchdog_timeo <= 0)
461 			dev->watchdog_timeo = 5*HZ;
462 		if (!mod_timer(&dev->watchdog_timer,
463 			       round_jiffies(jiffies + dev->watchdog_timeo)))
464 			dev_hold(dev);
465 	}
466 }
467 EXPORT_SYMBOL_GPL(__netdev_watchdog_up);
468 
469 static void dev_watchdog_up(struct net_device *dev)
470 {
471 	__netdev_watchdog_up(dev);
472 }
473 
474 static void dev_watchdog_down(struct net_device *dev)
475 {
476 	netif_tx_lock_bh(dev);
477 	if (del_timer(&dev->watchdog_timer))
478 		dev_put(dev);
479 	netif_tx_unlock_bh(dev);
480 }
481 
482 /**
483  *	netif_carrier_on - set carrier
484  *	@dev: network device
485  *
486  * Device has detected acquisition of carrier.
487  */
488 void netif_carrier_on(struct net_device *dev)
489 {
490 	if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
491 		if (dev->reg_state == NETREG_UNINITIALIZED)
492 			return;
493 		atomic_inc(&dev->carrier_up_count);
494 		linkwatch_fire_event(dev);
495 		if (netif_running(dev))
496 			__netdev_watchdog_up(dev);
497 	}
498 }
499 EXPORT_SYMBOL(netif_carrier_on);
500 
501 /**
502  *	netif_carrier_off - clear carrier
503  *	@dev: network device
504  *
505  * Device has detected loss of carrier.
506  */
507 void netif_carrier_off(struct net_device *dev)
508 {
509 	if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
510 		if (dev->reg_state == NETREG_UNINITIALIZED)
511 			return;
512 		atomic_inc(&dev->carrier_down_count);
513 		linkwatch_fire_event(dev);
514 	}
515 }
516 EXPORT_SYMBOL(netif_carrier_off);
517 
518 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
519    under all circumstances. It is difficult to invent anything faster or
520    cheaper.
521  */
522 
523 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
524 			struct sk_buff **to_free)
525 {
526 	__qdisc_drop(skb, to_free);
527 	return NET_XMIT_CN;
528 }
529 
530 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
531 {
532 	return NULL;
533 }
534 
535 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
536 	.id		=	"noop",
537 	.priv_size	=	0,
538 	.enqueue	=	noop_enqueue,
539 	.dequeue	=	noop_dequeue,
540 	.peek		=	noop_dequeue,
541 	.owner		=	THIS_MODULE,
542 };
543 
544 static struct netdev_queue noop_netdev_queue = {
545 	RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
546 	.qdisc_sleeping	=	&noop_qdisc,
547 };
548 
549 struct Qdisc noop_qdisc = {
550 	.enqueue	=	noop_enqueue,
551 	.dequeue	=	noop_dequeue,
552 	.flags		=	TCQ_F_BUILTIN,
553 	.ops		=	&noop_qdisc_ops,
554 	.q.lock		=	__SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
555 	.dev_queue	=	&noop_netdev_queue,
556 	.running	=	SEQCNT_ZERO(noop_qdisc.running),
557 	.busylock	=	__SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
558 	.gso_skb = {
559 		.next = (struct sk_buff *)&noop_qdisc.gso_skb,
560 		.prev = (struct sk_buff *)&noop_qdisc.gso_skb,
561 		.qlen = 0,
562 		.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
563 	},
564 	.skb_bad_txq = {
565 		.next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
566 		.prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
567 		.qlen = 0,
568 		.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
569 	},
570 };
571 EXPORT_SYMBOL(noop_qdisc);
572 
573 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
574 			struct netlink_ext_ack *extack)
575 {
576 	/* register_qdisc() assigns a default of noop_enqueue if unset,
577 	 * but __dev_queue_xmit() treats noqueue only as such
578 	 * if this is NULL - so clear it here. */
579 	qdisc->enqueue = NULL;
580 	return 0;
581 }
582 
583 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
584 	.id		=	"noqueue",
585 	.priv_size	=	0,
586 	.init		=	noqueue_init,
587 	.enqueue	=	noop_enqueue,
588 	.dequeue	=	noop_dequeue,
589 	.peek		=	noop_dequeue,
590 	.owner		=	THIS_MODULE,
591 };
592 
593 static const u8 prio2band[TC_PRIO_MAX + 1] = {
594 	1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
595 };
596 
597 /* 3-band FIFO queue: old style, but should be a bit faster than
598    generic prio+fifo combination.
599  */
600 
601 #define PFIFO_FAST_BANDS 3
602 
603 /*
604  * Private data for a pfifo_fast scheduler containing:
605  *	- rings for priority bands
606  */
607 struct pfifo_fast_priv {
608 	struct skb_array q[PFIFO_FAST_BANDS];
609 };
610 
611 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
612 					  int band)
613 {
614 	return &priv->q[band];
615 }
616 
617 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
618 			      struct sk_buff **to_free)
619 {
620 	int band = prio2band[skb->priority & TC_PRIO_MAX];
621 	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
622 	struct skb_array *q = band2list(priv, band);
623 	unsigned int pkt_len = qdisc_pkt_len(skb);
624 	int err;
625 
626 	err = skb_array_produce(q, skb);
627 
628 	if (unlikely(err)) {
629 		if (qdisc_is_percpu_stats(qdisc))
630 			return qdisc_drop_cpu(skb, qdisc, to_free);
631 		else
632 			return qdisc_drop(skb, qdisc, to_free);
633 	}
634 
635 	qdisc_update_stats_at_enqueue(qdisc, pkt_len);
636 	return NET_XMIT_SUCCESS;
637 }
638 
639 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
640 {
641 	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
642 	struct sk_buff *skb = NULL;
643 	int band;
644 
645 	for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
646 		struct skb_array *q = band2list(priv, band);
647 
648 		if (__skb_array_empty(q))
649 			continue;
650 
651 		skb = __skb_array_consume(q);
652 	}
653 	if (likely(skb)) {
654 		qdisc_update_stats_at_dequeue(qdisc, skb);
655 	} else {
656 		WRITE_ONCE(qdisc->empty, true);
657 	}
658 
659 	return skb;
660 }
661 
662 static struct sk_buff *pfifo_fast_peek(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 		skb = __skb_array_peek(q);
672 	}
673 
674 	return skb;
675 }
676 
677 static void pfifo_fast_reset(struct Qdisc *qdisc)
678 {
679 	int i, band;
680 	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
681 
682 	for (band = 0; band < PFIFO_FAST_BANDS; band++) {
683 		struct skb_array *q = band2list(priv, band);
684 		struct sk_buff *skb;
685 
686 		/* NULL ring is possible if destroy path is due to a failed
687 		 * skb_array_init() in pfifo_fast_init() case.
688 		 */
689 		if (!q->ring.queue)
690 			continue;
691 
692 		while ((skb = __skb_array_consume(q)) != NULL)
693 			kfree_skb(skb);
694 	}
695 
696 	if (qdisc_is_percpu_stats(qdisc)) {
697 		for_each_possible_cpu(i) {
698 			struct gnet_stats_queue *q;
699 
700 			q = per_cpu_ptr(qdisc->cpu_qstats, i);
701 			q->backlog = 0;
702 			q->qlen = 0;
703 		}
704 	}
705 }
706 
707 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
708 {
709 	struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
710 
711 	memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
712 	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
713 		goto nla_put_failure;
714 	return skb->len;
715 
716 nla_put_failure:
717 	return -1;
718 }
719 
720 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
721 			   struct netlink_ext_ack *extack)
722 {
723 	unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
724 	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
725 	int prio;
726 
727 	/* guard against zero length rings */
728 	if (!qlen)
729 		return -EINVAL;
730 
731 	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
732 		struct skb_array *q = band2list(priv, prio);
733 		int err;
734 
735 		err = skb_array_init(q, qlen, GFP_KERNEL);
736 		if (err)
737 			return -ENOMEM;
738 	}
739 
740 	/* Can by-pass the queue discipline */
741 	qdisc->flags |= TCQ_F_CAN_BYPASS;
742 	return 0;
743 }
744 
745 static void pfifo_fast_destroy(struct Qdisc *sch)
746 {
747 	struct pfifo_fast_priv *priv = qdisc_priv(sch);
748 	int prio;
749 
750 	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
751 		struct skb_array *q = band2list(priv, prio);
752 
753 		/* NULL ring is possible if destroy path is due to a failed
754 		 * skb_array_init() in pfifo_fast_init() case.
755 		 */
756 		if (!q->ring.queue)
757 			continue;
758 		/* Destroy ring but no need to kfree_skb because a call to
759 		 * pfifo_fast_reset() has already done that work.
760 		 */
761 		ptr_ring_cleanup(&q->ring, NULL);
762 	}
763 }
764 
765 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
766 					  unsigned int new_len)
767 {
768 	struct pfifo_fast_priv *priv = qdisc_priv(sch);
769 	struct skb_array *bands[PFIFO_FAST_BANDS];
770 	int prio;
771 
772 	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
773 		struct skb_array *q = band2list(priv, prio);
774 
775 		bands[prio] = q;
776 	}
777 
778 	return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
779 					 GFP_KERNEL);
780 }
781 
782 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
783 	.id		=	"pfifo_fast",
784 	.priv_size	=	sizeof(struct pfifo_fast_priv),
785 	.enqueue	=	pfifo_fast_enqueue,
786 	.dequeue	=	pfifo_fast_dequeue,
787 	.peek		=	pfifo_fast_peek,
788 	.init		=	pfifo_fast_init,
789 	.destroy	=	pfifo_fast_destroy,
790 	.reset		=	pfifo_fast_reset,
791 	.dump		=	pfifo_fast_dump,
792 	.change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
793 	.owner		=	THIS_MODULE,
794 	.static_flags	=	TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
795 };
796 EXPORT_SYMBOL(pfifo_fast_ops);
797 
798 static struct lock_class_key qdisc_tx_busylock;
799 static struct lock_class_key qdisc_running_key;
800 
801 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
802 			  const struct Qdisc_ops *ops,
803 			  struct netlink_ext_ack *extack)
804 {
805 	struct Qdisc *sch;
806 	unsigned int size = sizeof(*sch) + ops->priv_size;
807 	int err = -ENOBUFS;
808 	struct net_device *dev;
809 
810 	if (!dev_queue) {
811 		NL_SET_ERR_MSG(extack, "No device queue given");
812 		err = -EINVAL;
813 		goto errout;
814 	}
815 
816 	dev = dev_queue->dev;
817 	sch = kzalloc_node(size, GFP_KERNEL, netdev_queue_numa_node_read(dev_queue));
818 
819 	if (!sch)
820 		goto errout;
821 	__skb_queue_head_init(&sch->gso_skb);
822 	__skb_queue_head_init(&sch->skb_bad_txq);
823 	qdisc_skb_head_init(&sch->q);
824 	spin_lock_init(&sch->q.lock);
825 
826 	if (ops->static_flags & TCQ_F_CPUSTATS) {
827 		sch->cpu_bstats =
828 			netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
829 		if (!sch->cpu_bstats)
830 			goto errout1;
831 
832 		sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
833 		if (!sch->cpu_qstats) {
834 			free_percpu(sch->cpu_bstats);
835 			goto errout1;
836 		}
837 	}
838 
839 	spin_lock_init(&sch->busylock);
840 	lockdep_set_class(&sch->busylock,
841 			  dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
842 
843 	/* seqlock has the same scope of busylock, for NOLOCK qdisc */
844 	spin_lock_init(&sch->seqlock);
845 	lockdep_set_class(&sch->busylock,
846 			  dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
847 
848 	seqcount_init(&sch->running);
849 	lockdep_set_class(&sch->running,
850 			  dev->qdisc_running_key ?: &qdisc_running_key);
851 
852 	sch->ops = ops;
853 	sch->flags = ops->static_flags;
854 	sch->enqueue = ops->enqueue;
855 	sch->dequeue = ops->dequeue;
856 	sch->dev_queue = dev_queue;
857 	sch->empty = true;
858 	dev_hold(dev);
859 	refcount_set(&sch->refcnt, 1);
860 
861 	return sch;
862 errout1:
863 	kfree(sch);
864 errout:
865 	return ERR_PTR(err);
866 }
867 
868 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
869 				const struct Qdisc_ops *ops,
870 				unsigned int parentid,
871 				struct netlink_ext_ack *extack)
872 {
873 	struct Qdisc *sch;
874 
875 	if (!try_module_get(ops->owner)) {
876 		NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
877 		return NULL;
878 	}
879 
880 	sch = qdisc_alloc(dev_queue, ops, extack);
881 	if (IS_ERR(sch)) {
882 		module_put(ops->owner);
883 		return NULL;
884 	}
885 	sch->parent = parentid;
886 
887 	if (!ops->init || ops->init(sch, NULL, extack) == 0) {
888 		trace_qdisc_create(ops, dev_queue->dev, parentid);
889 		return sch;
890 	}
891 
892 	qdisc_put(sch);
893 	return NULL;
894 }
895 EXPORT_SYMBOL(qdisc_create_dflt);
896 
897 /* Under qdisc_lock(qdisc) and BH! */
898 
899 void qdisc_reset(struct Qdisc *qdisc)
900 {
901 	const struct Qdisc_ops *ops = qdisc->ops;
902 	struct sk_buff *skb, *tmp;
903 
904 	trace_qdisc_reset(qdisc);
905 
906 	if (ops->reset)
907 		ops->reset(qdisc);
908 
909 	skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
910 		__skb_unlink(skb, &qdisc->gso_skb);
911 		kfree_skb_list(skb);
912 	}
913 
914 	skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
915 		__skb_unlink(skb, &qdisc->skb_bad_txq);
916 		kfree_skb_list(skb);
917 	}
918 
919 	qdisc->q.qlen = 0;
920 	qdisc->qstats.backlog = 0;
921 }
922 EXPORT_SYMBOL(qdisc_reset);
923 
924 void qdisc_free(struct Qdisc *qdisc)
925 {
926 	if (qdisc_is_percpu_stats(qdisc)) {
927 		free_percpu(qdisc->cpu_bstats);
928 		free_percpu(qdisc->cpu_qstats);
929 	}
930 
931 	kfree(qdisc);
932 }
933 
934 static void qdisc_free_cb(struct rcu_head *head)
935 {
936 	struct Qdisc *q = container_of(head, struct Qdisc, rcu);
937 
938 	qdisc_free(q);
939 }
940 
941 static void qdisc_destroy(struct Qdisc *qdisc)
942 {
943 	const struct Qdisc_ops  *ops = qdisc->ops;
944 
945 #ifdef CONFIG_NET_SCHED
946 	qdisc_hash_del(qdisc);
947 
948 	qdisc_put_stab(rtnl_dereference(qdisc->stab));
949 #endif
950 	gen_kill_estimator(&qdisc->rate_est);
951 
952 	qdisc_reset(qdisc);
953 
954 	if (ops->destroy)
955 		ops->destroy(qdisc);
956 
957 	module_put(ops->owner);
958 	dev_put(qdisc_dev(qdisc));
959 
960 	trace_qdisc_destroy(qdisc);
961 
962 	call_rcu(&qdisc->rcu, qdisc_free_cb);
963 }
964 
965 void qdisc_put(struct Qdisc *qdisc)
966 {
967 	if (!qdisc)
968 		return;
969 
970 	if (qdisc->flags & TCQ_F_BUILTIN ||
971 	    !refcount_dec_and_test(&qdisc->refcnt))
972 		return;
973 
974 	qdisc_destroy(qdisc);
975 }
976 EXPORT_SYMBOL(qdisc_put);
977 
978 /* Version of qdisc_put() that is called with rtnl mutex unlocked.
979  * Intended to be used as optimization, this function only takes rtnl lock if
980  * qdisc reference counter reached zero.
981  */
982 
983 void qdisc_put_unlocked(struct Qdisc *qdisc)
984 {
985 	if (qdisc->flags & TCQ_F_BUILTIN ||
986 	    !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
987 		return;
988 
989 	qdisc_destroy(qdisc);
990 	rtnl_unlock();
991 }
992 EXPORT_SYMBOL(qdisc_put_unlocked);
993 
994 /* Attach toplevel qdisc to device queue. */
995 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
996 			      struct Qdisc *qdisc)
997 {
998 	struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
999 	spinlock_t *root_lock;
1000 
1001 	root_lock = qdisc_lock(oqdisc);
1002 	spin_lock_bh(root_lock);
1003 
1004 	/* ... and graft new one */
1005 	if (qdisc == NULL)
1006 		qdisc = &noop_qdisc;
1007 	dev_queue->qdisc_sleeping = qdisc;
1008 	rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1009 
1010 	spin_unlock_bh(root_lock);
1011 
1012 	return oqdisc;
1013 }
1014 EXPORT_SYMBOL(dev_graft_qdisc);
1015 
1016 static void attach_one_default_qdisc(struct net_device *dev,
1017 				     struct netdev_queue *dev_queue,
1018 				     void *_unused)
1019 {
1020 	struct Qdisc *qdisc;
1021 	const struct Qdisc_ops *ops = default_qdisc_ops;
1022 
1023 	if (dev->priv_flags & IFF_NO_QUEUE)
1024 		ops = &noqueue_qdisc_ops;
1025 	else if(dev->type == ARPHRD_CAN)
1026 		ops = &pfifo_fast_ops;
1027 
1028 	qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1029 	if (!qdisc)
1030 		return;
1031 
1032 	if (!netif_is_multiqueue(dev))
1033 		qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1034 	dev_queue->qdisc_sleeping = qdisc;
1035 }
1036 
1037 static void attach_default_qdiscs(struct net_device *dev)
1038 {
1039 	struct netdev_queue *txq;
1040 	struct Qdisc *qdisc;
1041 
1042 	txq = netdev_get_tx_queue(dev, 0);
1043 
1044 	if (!netif_is_multiqueue(dev) ||
1045 	    dev->priv_flags & IFF_NO_QUEUE) {
1046 		netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1047 		dev->qdisc = txq->qdisc_sleeping;
1048 		qdisc_refcount_inc(dev->qdisc);
1049 	} else {
1050 		qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1051 		if (qdisc) {
1052 			dev->qdisc = qdisc;
1053 			qdisc->ops->attach(qdisc);
1054 		}
1055 	}
1056 
1057 	/* Detect default qdisc setup/init failed and fallback to "noqueue" */
1058 	if (dev->qdisc == &noop_qdisc) {
1059 		netdev_warn(dev, "default qdisc (%s) fail, fallback to %s\n",
1060 			    default_qdisc_ops->id, noqueue_qdisc_ops.id);
1061 		dev->priv_flags |= IFF_NO_QUEUE;
1062 		netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1063 		dev->qdisc = txq->qdisc_sleeping;
1064 		qdisc_refcount_inc(dev->qdisc);
1065 		dev->priv_flags ^= IFF_NO_QUEUE;
1066 	}
1067 
1068 #ifdef CONFIG_NET_SCHED
1069 	if (dev->qdisc != &noop_qdisc)
1070 		qdisc_hash_add(dev->qdisc, false);
1071 #endif
1072 }
1073 
1074 static void transition_one_qdisc(struct net_device *dev,
1075 				 struct netdev_queue *dev_queue,
1076 				 void *_need_watchdog)
1077 {
1078 	struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1079 	int *need_watchdog_p = _need_watchdog;
1080 
1081 	if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1082 		clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1083 
1084 	rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1085 	if (need_watchdog_p) {
1086 		dev_queue->trans_start = 0;
1087 		*need_watchdog_p = 1;
1088 	}
1089 }
1090 
1091 void dev_activate(struct net_device *dev)
1092 {
1093 	int need_watchdog;
1094 
1095 	/* No queueing discipline is attached to device;
1096 	 * create default one for devices, which need queueing
1097 	 * and noqueue_qdisc for virtual interfaces
1098 	 */
1099 
1100 	if (dev->qdisc == &noop_qdisc)
1101 		attach_default_qdiscs(dev);
1102 
1103 	if (!netif_carrier_ok(dev))
1104 		/* Delay activation until next carrier-on event */
1105 		return;
1106 
1107 	need_watchdog = 0;
1108 	netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1109 	if (dev_ingress_queue(dev))
1110 		transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1111 
1112 	if (need_watchdog) {
1113 		netif_trans_update(dev);
1114 		dev_watchdog_up(dev);
1115 	}
1116 }
1117 EXPORT_SYMBOL(dev_activate);
1118 
1119 static void qdisc_deactivate(struct Qdisc *qdisc)
1120 {
1121 	if (qdisc->flags & TCQ_F_BUILTIN)
1122 		return;
1123 
1124 	set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1125 }
1126 
1127 static void dev_deactivate_queue(struct net_device *dev,
1128 				 struct netdev_queue *dev_queue,
1129 				 void *_qdisc_default)
1130 {
1131 	struct Qdisc *qdisc_default = _qdisc_default;
1132 	struct Qdisc *qdisc;
1133 
1134 	qdisc = rtnl_dereference(dev_queue->qdisc);
1135 	if (qdisc) {
1136 		qdisc_deactivate(qdisc);
1137 		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1138 	}
1139 }
1140 
1141 static void dev_reset_queue(struct net_device *dev,
1142 			    struct netdev_queue *dev_queue,
1143 			    void *_unused)
1144 {
1145 	struct Qdisc *qdisc;
1146 	bool nolock;
1147 
1148 	qdisc = dev_queue->qdisc_sleeping;
1149 	if (!qdisc)
1150 		return;
1151 
1152 	nolock = qdisc->flags & TCQ_F_NOLOCK;
1153 
1154 	if (nolock)
1155 		spin_lock_bh(&qdisc->seqlock);
1156 	spin_lock_bh(qdisc_lock(qdisc));
1157 
1158 	qdisc_reset(qdisc);
1159 
1160 	spin_unlock_bh(qdisc_lock(qdisc));
1161 	if (nolock)
1162 		spin_unlock_bh(&qdisc->seqlock);
1163 }
1164 
1165 static bool some_qdisc_is_busy(struct net_device *dev)
1166 {
1167 	unsigned int i;
1168 
1169 	for (i = 0; i < dev->num_tx_queues; i++) {
1170 		struct netdev_queue *dev_queue;
1171 		spinlock_t *root_lock;
1172 		struct Qdisc *q;
1173 		int val;
1174 
1175 		dev_queue = netdev_get_tx_queue(dev, i);
1176 		q = dev_queue->qdisc_sleeping;
1177 
1178 		root_lock = qdisc_lock(q);
1179 		spin_lock_bh(root_lock);
1180 
1181 		val = (qdisc_is_running(q) ||
1182 		       test_bit(__QDISC_STATE_SCHED, &q->state));
1183 
1184 		spin_unlock_bh(root_lock);
1185 
1186 		if (val)
1187 			return true;
1188 	}
1189 	return false;
1190 }
1191 
1192 /**
1193  * 	dev_deactivate_many - deactivate transmissions on several devices
1194  * 	@head: list of devices to deactivate
1195  *
1196  *	This function returns only when all outstanding transmissions
1197  *	have completed, unless all devices are in dismantle phase.
1198  */
1199 void dev_deactivate_many(struct list_head *head)
1200 {
1201 	struct net_device *dev;
1202 
1203 	list_for_each_entry(dev, head, close_list) {
1204 		netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1205 					 &noop_qdisc);
1206 		if (dev_ingress_queue(dev))
1207 			dev_deactivate_queue(dev, dev_ingress_queue(dev),
1208 					     &noop_qdisc);
1209 
1210 		dev_watchdog_down(dev);
1211 	}
1212 
1213 	/* Wait for outstanding qdisc-less dev_queue_xmit calls or
1214 	 * outstanding qdisc enqueuing calls.
1215 	 * This is avoided if all devices are in dismantle phase :
1216 	 * Caller will call synchronize_net() for us
1217 	 */
1218 	synchronize_net();
1219 
1220 	list_for_each_entry(dev, head, close_list) {
1221 		netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);
1222 
1223 		if (dev_ingress_queue(dev))
1224 			dev_reset_queue(dev, dev_ingress_queue(dev), NULL);
1225 	}
1226 
1227 	/* Wait for outstanding qdisc_run calls. */
1228 	list_for_each_entry(dev, head, close_list) {
1229 		while (some_qdisc_is_busy(dev)) {
1230 			/* wait_event() would avoid this sleep-loop but would
1231 			 * require expensive checks in the fast paths of packet
1232 			 * processing which isn't worth it.
1233 			 */
1234 			schedule_timeout_uninterruptible(1);
1235 		}
1236 	}
1237 }
1238 
1239 void dev_deactivate(struct net_device *dev)
1240 {
1241 	LIST_HEAD(single);
1242 
1243 	list_add(&dev->close_list, &single);
1244 	dev_deactivate_many(&single);
1245 	list_del(&single);
1246 }
1247 EXPORT_SYMBOL(dev_deactivate);
1248 
1249 static int qdisc_change_tx_queue_len(struct net_device *dev,
1250 				     struct netdev_queue *dev_queue)
1251 {
1252 	struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1253 	const struct Qdisc_ops *ops = qdisc->ops;
1254 
1255 	if (ops->change_tx_queue_len)
1256 		return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1257 	return 0;
1258 }
1259 
1260 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1261 {
1262 	bool up = dev->flags & IFF_UP;
1263 	unsigned int i;
1264 	int ret = 0;
1265 
1266 	if (up)
1267 		dev_deactivate(dev);
1268 
1269 	for (i = 0; i < dev->num_tx_queues; i++) {
1270 		ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1271 
1272 		/* TODO: revert changes on a partial failure */
1273 		if (ret)
1274 			break;
1275 	}
1276 
1277 	if (up)
1278 		dev_activate(dev);
1279 	return ret;
1280 }
1281 
1282 static void dev_init_scheduler_queue(struct net_device *dev,
1283 				     struct netdev_queue *dev_queue,
1284 				     void *_qdisc)
1285 {
1286 	struct Qdisc *qdisc = _qdisc;
1287 
1288 	rcu_assign_pointer(dev_queue->qdisc, qdisc);
1289 	dev_queue->qdisc_sleeping = qdisc;
1290 }
1291 
1292 void dev_init_scheduler(struct net_device *dev)
1293 {
1294 	dev->qdisc = &noop_qdisc;
1295 	netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1296 	if (dev_ingress_queue(dev))
1297 		dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1298 
1299 	timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1300 }
1301 
1302 static void shutdown_scheduler_queue(struct net_device *dev,
1303 				     struct netdev_queue *dev_queue,
1304 				     void *_qdisc_default)
1305 {
1306 	struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1307 	struct Qdisc *qdisc_default = _qdisc_default;
1308 
1309 	if (qdisc) {
1310 		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1311 		dev_queue->qdisc_sleeping = qdisc_default;
1312 
1313 		qdisc_put(qdisc);
1314 	}
1315 }
1316 
1317 void dev_shutdown(struct net_device *dev)
1318 {
1319 	netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1320 	if (dev_ingress_queue(dev))
1321 		shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1322 	qdisc_put(dev->qdisc);
1323 	dev->qdisc = &noop_qdisc;
1324 
1325 	WARN_ON(timer_pending(&dev->watchdog_timer));
1326 }
1327 
1328 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1329 			       const struct tc_ratespec *conf,
1330 			       u64 rate64)
1331 {
1332 	memset(r, 0, sizeof(*r));
1333 	r->overhead = conf->overhead;
1334 	r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1335 	r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1336 	r->mult = 1;
1337 	/*
1338 	 * The deal here is to replace a divide by a reciprocal one
1339 	 * in fast path (a reciprocal divide is a multiply and a shift)
1340 	 *
1341 	 * Normal formula would be :
1342 	 *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1343 	 *
1344 	 * We compute mult/shift to use instead :
1345 	 *  time_in_ns = (len * mult) >> shift;
1346 	 *
1347 	 * We try to get the highest possible mult value for accuracy,
1348 	 * but have to make sure no overflows will ever happen.
1349 	 */
1350 	if (r->rate_bytes_ps > 0) {
1351 		u64 factor = NSEC_PER_SEC;
1352 
1353 		for (;;) {
1354 			r->mult = div64_u64(factor, r->rate_bytes_ps);
1355 			if (r->mult & (1U << 31) || factor & (1ULL << 63))
1356 				break;
1357 			factor <<= 1;
1358 			r->shift++;
1359 		}
1360 	}
1361 }
1362 EXPORT_SYMBOL(psched_ratecfg_precompute);
1363 
1364 static void mini_qdisc_rcu_func(struct rcu_head *head)
1365 {
1366 }
1367 
1368 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1369 			  struct tcf_proto *tp_head)
1370 {
1371 	/* Protected with chain0->filter_chain_lock.
1372 	 * Can't access chain directly because tp_head can be NULL.
1373 	 */
1374 	struct mini_Qdisc *miniq_old =
1375 		rcu_dereference_protected(*miniqp->p_miniq, 1);
1376 	struct mini_Qdisc *miniq;
1377 
1378 	if (!tp_head) {
1379 		RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1380 		/* Wait for flying RCU callback before it is freed. */
1381 		rcu_barrier();
1382 		return;
1383 	}
1384 
1385 	miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
1386 		&miniqp->miniq1 : &miniqp->miniq2;
1387 
1388 	/* We need to make sure that readers won't see the miniq
1389 	 * we are about to modify. So wait until previous call_rcu callback
1390 	 * is done.
1391 	 */
1392 	rcu_barrier();
1393 	miniq->filter_list = tp_head;
1394 	rcu_assign_pointer(*miniqp->p_miniq, miniq);
1395 
1396 	if (miniq_old)
1397 		/* This is counterpart of the rcu barriers above. We need to
1398 		 * block potential new user of miniq_old until all readers
1399 		 * are not seeing it.
1400 		 */
1401 		call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func);
1402 }
1403 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1404 
1405 void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
1406 				struct tcf_block *block)
1407 {
1408 	miniqp->miniq1.block = block;
1409 	miniqp->miniq2.block = block;
1410 }
1411 EXPORT_SYMBOL(mini_qdisc_pair_block_init);
1412 
1413 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1414 			  struct mini_Qdisc __rcu **p_miniq)
1415 {
1416 	miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1417 	miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1418 	miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1419 	miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1420 	miniqp->p_miniq = p_miniq;
1421 }
1422 EXPORT_SYMBOL(mini_qdisc_pair_init);
1423