1/*
  2 * net/sched/sch_generic.c	Generic packet scheduler routines.
  3 *
  4 *		This program is free software; you can redistribute it and/or
  5 *		modify it under the terms of the GNU General Public License
  6 *		as published by the Free Software Foundation; either version
  7 *		2 of the License, or (at your option) any later version.
  8 *
  9 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 10 *              Jamal Hadi Salim, <hadi@cyberus.ca> 990601
 11 *              - Ingress support
 12 */
 13
 14#include <linux/bitops.h>
 15#include <linux/module.h>
 16#include <linux/types.h>
 17#include <linux/kernel.h>
 18#include <linux/sched.h>
 19#include <linux/string.h>
 20#include <linux/errno.h>
 21#include <linux/netdevice.h>
 22#include <linux/skbuff.h>
 23#include <linux/rtnetlink.h>
 24#include <linux/init.h>
 25#include <linux/rcupdate.h>
 26#include <linux/list.h>
 27#include <linux/slab.h>
 
 
 
 
 28#include <net/pkt_sched.h>
 29#include <net/dst.h>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 30
 31/* Main transmission queue. */
 32
 33/* Modifications to data participating in scheduling must be protected with
 34 * qdisc_lock(qdisc) spinlock.
 35 *
 36 * The idea is the following:
 37 * - enqueue, dequeue are serialized via qdisc root lock
 38 * - ingress filtering is also serialized via qdisc root lock
 39 * - updates to tree and tree walking are only done under the rtnl mutex.
 40 */
 41
 42static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
 
 
 43{
 44	skb_dst_force(skb);
 45	q->gso_skb = skb;
 46	q->qstats.requeues++;
 47	q->q.qlen++;	/* it's still part of the queue */
 48	__netif_schedule(q);
 49
 50	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 51}
 52
 53static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
 54{
 55	struct sk_buff *skb = q->gso_skb;
 56
 57	if (unlikely(skb)) {
 58		struct net_device *dev = qdisc_dev(q);
 59		struct netdev_queue *txq;
 60
 61		/* check the reason of requeuing without tx lock first */
 62		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 63		if (!netif_xmit_frozen_or_stopped(txq)) {
 64			q->gso_skb = NULL;
 65			q->q.qlen--;
 66		} else
 67			skb = NULL;
 
 
 
 
 
 
 
 
 
 
 
 68	} else {
 69		skb = q->dequeue(q);
 
 70	}
 71
 72	return skb;
 
 73}
 74
 75static inline int handle_dev_cpu_collision(struct sk_buff *skb,
 76					   struct netdev_queue *dev_queue,
 77					   struct Qdisc *q)
 78{
 79	int ret;
 80
 81	if (unlikely(dev_queue->xmit_lock_owner == smp_processor_id())) {
 82		/*
 83		 * Same CPU holding the lock. It may be a transient
 84		 * configuration error, when hard_start_xmit() recurses. We
 85		 * detect it by checking xmit owner and drop the packet when
 86		 * deadloop is detected. Return OK to try the next skb.
 87		 */
 88		kfree_skb(skb);
 89		net_warn_ratelimited("Dead loop on netdevice %s, fix it urgently!\n",
 90				     dev_queue->dev->name);
 91		ret = qdisc_qlen(q);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 92	} else {
 93		/*
 94		 * Another cpu is holding lock, requeue & delay xmits for
 95		 * some time.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 96		 */
 97		__this_cpu_inc(softnet_data.cpu_collision);
 98		ret = dev_requeue_skb(skb, q);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 99	}
100
101	return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
102}
103
104/*
105 * Transmit one skb, and handle the return status as required. Holding the
106 * __QDISC_STATE_RUNNING bit guarantees that only one CPU can execute this
107 * function.
108 *
109 * Returns to the caller:
110 *				0  - queue is empty or throttled.
111 *				>0 - queue is not empty.
112 */
113int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
114		    struct net_device *dev, struct netdev_queue *txq,
115		    spinlock_t *root_lock)
116{
117	int ret = NETDEV_TX_BUSY;
 
118
119	/* And release qdisc */
120	spin_unlock(root_lock);
 
121
122	HARD_TX_LOCK(dev, txq, smp_processor_id());
123	if (!netif_xmit_frozen_or_stopped(txq))
124		ret = dev_hard_start_xmit(skb, dev, txq);
 
 
 
 
 
125
126	HARD_TX_UNLOCK(dev, txq);
 
 
 
127
128	spin_lock(root_lock);
 
 
 
 
 
129
130	if (dev_xmit_complete(ret)) {
131		/* Driver sent out skb successfully or skb was consumed */
132		ret = qdisc_qlen(q);
133	} else if (ret == NETDEV_TX_LOCKED) {
134		/* Driver try lock failed */
135		ret = handle_dev_cpu_collision(skb, txq, q);
136	} else {
 
 
 
 
 
 
 
 
 
137		/* Driver returned NETDEV_TX_BUSY - requeue skb */
138		if (unlikely(ret != NETDEV_TX_BUSY))
139			net_warn_ratelimited("BUG %s code %d qlen %d\n",
140					     dev->name, ret, q->q.qlen);
141
142		ret = dev_requeue_skb(skb, q);
 
143	}
144
145	if (ret && netif_xmit_frozen_or_stopped(txq))
146		ret = 0;
147
148	return ret;
149}
150
151/*
152 * NOTE: Called under qdisc_lock(q) with locally disabled BH.
153 *
154 * __QDISC_STATE_RUNNING guarantees only one CPU can process
155 * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
156 * this queue.
157 *
158 *  netif_tx_lock serializes accesses to device driver.
159 *
160 *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
161 *  if one is grabbed, another must be free.
162 *
163 * Note, that this procedure can be called by a watchdog timer
164 *
165 * Returns to the caller:
166 *				0  - queue is empty or throttled.
167 *				>0 - queue is not empty.
168 *
169 */
170static inline int qdisc_restart(struct Qdisc *q)
171{
 
172	struct netdev_queue *txq;
173	struct net_device *dev;
174	spinlock_t *root_lock;
175	struct sk_buff *skb;
 
176
177	/* Dequeue packet */
178	skb = dequeue_skb(q);
179	if (unlikely(!skb))
180		return 0;
181	WARN_ON_ONCE(skb_dst_is_noref(skb));
182	root_lock = qdisc_lock(q);
 
 
183	dev = qdisc_dev(q);
184	txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
185
186	return sch_direct_xmit(skb, q, dev, txq, root_lock);
187}
188
189void __qdisc_run(struct Qdisc *q)
190{
191	int quota = weight_p;
 
 
 
 
 
 
 
 
 
192
193	while (qdisc_restart(q)) {
194		/*
195		 * Ordered by possible occurrence: Postpone processing if
196		 * 1. we've exceeded packet quota
197		 * 2. another process needs the CPU;
198		 */
199		if (--quota <= 0 || need_resched()) {
200			__netif_schedule(q);
201			break;
202		}
203	}
204
205	qdisc_run_end(q);
206}
207
208unsigned long dev_trans_start(struct net_device *dev)
209{
210	unsigned long val, res = dev->trans_start;
211	unsigned int i;
212
213	for (i = 0; i < dev->num_tx_queues; i++) {
 
 
 
 
 
214		val = netdev_get_tx_queue(dev, i)->trans_start;
215		if (val && time_after(val, res))
216			res = val;
217	}
218	dev->trans_start = res;
219	return res;
220}
221EXPORT_SYMBOL(dev_trans_start);
222
223static void dev_watchdog(unsigned long arg)
224{
225	struct net_device *dev = (struct net_device *)arg;
226
227	netif_tx_lock(dev);
228	if (!qdisc_tx_is_noop(dev)) {
229		if (netif_device_present(dev) &&
230		    netif_running(dev) &&
231		    netif_carrier_ok(dev)) {
232			int some_queue_timedout = 0;
233			unsigned int i;
234			unsigned long trans_start;
235
236			for (i = 0; i < dev->num_tx_queues; i++) {
237				struct netdev_queue *txq;
238
239				txq = netdev_get_tx_queue(dev, i);
240				/*
241				 * old device drivers set dev->trans_start
242				 */
243				trans_start = txq->trans_start ? : dev->trans_start;
244				if (netif_xmit_stopped(txq) &&
245				    time_after(jiffies, (trans_start +
246							 dev->watchdog_timeo))) {
247					some_queue_timedout = 1;
248					txq->trans_timeout++;
249					break;
250				}
251			}
252
253			if (some_queue_timedout) {
 
254				WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
255				       dev->name, netdev_drivername(dev), i);
256				dev->netdev_ops->ndo_tx_timeout(dev);
257			}
258			if (!mod_timer(&dev->watchdog_timer,
259				       round_jiffies(jiffies +
260						     dev->watchdog_timeo)))
261				dev_hold(dev);
262		}
263	}
264	netif_tx_unlock(dev);
265
266	dev_put(dev);
267}
268
269void __netdev_watchdog_up(struct net_device *dev)
270{
271	if (dev->netdev_ops->ndo_tx_timeout) {
272		if (dev->watchdog_timeo <= 0)
273			dev->watchdog_timeo = 5*HZ;
274		if (!mod_timer(&dev->watchdog_timer,
275			       round_jiffies(jiffies + dev->watchdog_timeo)))
276			dev_hold(dev);
277	}
278}
 
279
280static void dev_watchdog_up(struct net_device *dev)
281{
282	__netdev_watchdog_up(dev);
283}
284
285static void dev_watchdog_down(struct net_device *dev)
286{
287	netif_tx_lock_bh(dev);
288	if (del_timer(&dev->watchdog_timer))
289		dev_put(dev);
290	netif_tx_unlock_bh(dev);
291}
292
293/**
294 *	netif_carrier_on - set carrier
295 *	@dev: network device
296 *
297 * Device has detected that carrier.
298 */
299void netif_carrier_on(struct net_device *dev)
300{
301	if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
302		if (dev->reg_state == NETREG_UNINITIALIZED)
303			return;
 
304		linkwatch_fire_event(dev);
305		if (netif_running(dev))
306			__netdev_watchdog_up(dev);
307	}
308}
309EXPORT_SYMBOL(netif_carrier_on);
310
311/**
312 *	netif_carrier_off - clear carrier
313 *	@dev: network device
314 *
315 * Device has detected loss of carrier.
316 */
317void netif_carrier_off(struct net_device *dev)
318{
319	if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
320		if (dev->reg_state == NETREG_UNINITIALIZED)
321			return;
 
322		linkwatch_fire_event(dev);
323	}
324}
325EXPORT_SYMBOL(netif_carrier_off);
326
327/**
328 * 	netif_notify_peers - notify network peers about existence of @dev
329 * 	@dev: network device
330 *
331 * Generate traffic such that interested network peers are aware of
332 * @dev, such as by generating a gratuitous ARP. This may be used when
333 * a device wants to inform the rest of the network about some sort of
334 * reconfiguration such as a failover event or virtual machine
335 * migration.
336 */
337void netif_notify_peers(struct net_device *dev)
338{
339	rtnl_lock();
340	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
341	rtnl_unlock();
 
 
342}
343EXPORT_SYMBOL(netif_notify_peers);
344
345/* "NOOP" scheduler: the best scheduler, recommended for all interfaces
346   under all circumstances. It is difficult to invent anything faster or
347   cheaper.
348 */
349
350static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
 
351{
352	kfree_skb(skb);
353	return NET_XMIT_CN;
354}
355
356static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
357{
358	return NULL;
359}
360
361struct Qdisc_ops noop_qdisc_ops __read_mostly = {
362	.id		=	"noop",
363	.priv_size	=	0,
364	.enqueue	=	noop_enqueue,
365	.dequeue	=	noop_dequeue,
366	.peek		=	noop_dequeue,
367	.owner		=	THIS_MODULE,
368};
369
370static struct netdev_queue noop_netdev_queue = {
371	.qdisc		=	&noop_qdisc,
372	.qdisc_sleeping	=	&noop_qdisc,
373};
374
375struct Qdisc noop_qdisc = {
376	.enqueue	=	noop_enqueue,
377	.dequeue	=	noop_dequeue,
378	.flags		=	TCQ_F_BUILTIN,
379	.ops		=	&noop_qdisc_ops,
380	.list		=	LIST_HEAD_INIT(noop_qdisc.list),
381	.q.lock		=	__SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
382	.dev_queue	=	&noop_netdev_queue,
 
383	.busylock	=	__SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 
 
 
 
 
 
 
 
 
 
 
 
384};
385EXPORT_SYMBOL(noop_qdisc);
386
387static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 
 
 
 
 
 
 
 
 
 
388	.id		=	"noqueue",
389	.priv_size	=	0,
 
390	.enqueue	=	noop_enqueue,
391	.dequeue	=	noop_dequeue,
392	.peek		=	noop_dequeue,
393	.owner		=	THIS_MODULE,
394};
395
396static struct Qdisc noqueue_qdisc;
397static struct netdev_queue noqueue_netdev_queue = {
398	.qdisc		=	&noqueue_qdisc,
399	.qdisc_sleeping	=	&noqueue_qdisc,
400};
401
402static struct Qdisc noqueue_qdisc = {
403	.enqueue	=	NULL,
404	.dequeue	=	noop_dequeue,
405	.flags		=	TCQ_F_BUILTIN,
406	.ops		=	&noqueue_qdisc_ops,
407	.list		=	LIST_HEAD_INIT(noqueue_qdisc.list),
408	.q.lock		=	__SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
409	.dev_queue	=	&noqueue_netdev_queue,
410	.busylock	=	__SPIN_LOCK_UNLOCKED(noqueue_qdisc.busylock),
411};
412
413
414static const u8 prio2band[TC_PRIO_MAX + 1] = {
415	1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
416};
417
418/* 3-band FIFO queue: old style, but should be a bit faster than
419   generic prio+fifo combination.
420 */
421
422#define PFIFO_FAST_BANDS 3
423
424/*
425 * Private data for a pfifo_fast scheduler containing:
426 * 	- queues for the three band
427 * 	- bitmap indicating which of the bands contain skbs
428 */
429struct pfifo_fast_priv {
430	u32 bitmap;
431	struct sk_buff_head q[PFIFO_FAST_BANDS];
432};
433
434/*
435 * Convert a bitmap to the first band number where an skb is queued, where:
436 * 	bitmap=0 means there are no skbs on any band.
437 * 	bitmap=1 means there is an skb on band 0.
438 *	bitmap=7 means there are skbs on all 3 bands, etc.
439 */
440static const int bitmap2band[] = {-1, 0, 1, 0, 2, 0, 1, 0};
441
442static inline struct sk_buff_head *band2list(struct pfifo_fast_priv *priv,
443					     int band)
444{
445	return priv->q + band;
446}
447
448static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc)
 
449{
450	if (skb_queue_len(&qdisc->q) < qdisc_dev(qdisc)->tx_queue_len) {
451		int band = prio2band[skb->priority & TC_PRIO_MAX];
452		struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
453		struct sk_buff_head *list = band2list(priv, band);
 
 
 
454
455		priv->bitmap |= (1 << band);
456		qdisc->q.qlen++;
457		return __qdisc_enqueue_tail(skb, qdisc, list);
 
 
458	}
459
460	return qdisc_drop(skb, qdisc);
 
461}
462
463static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
464{
465	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
466	int band = bitmap2band[priv->bitmap];
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
467
468	if (likely(band >= 0)) {
469		struct sk_buff_head *list = band2list(priv, band);
470		struct sk_buff *skb = __qdisc_dequeue_head(qdisc, list);
471
472		qdisc->q.qlen--;
473		if (skb_queue_empty(list))
474			priv->bitmap &= ~(1 << band);
475
476		return skb;
477	}
478
479	return NULL;
480}
481
482static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
483{
484	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
485	int band = bitmap2band[priv->bitmap];
 
486
487	if (band >= 0) {
488		struct sk_buff_head *list = band2list(priv, band);
489
490		return skb_peek(list);
491	}
492
493	return NULL;
494}
495
496static void pfifo_fast_reset(struct Qdisc *qdisc)
497{
498	int prio;
499	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
500
501	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
502		__qdisc_reset_queue(qdisc, band2list(priv, prio));
 
503
504	priv->bitmap = 0;
505	qdisc->qstats.backlog = 0;
506	qdisc->q.qlen = 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
507}
508
509static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
510{
511	struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
512
513	memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
514	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
515		goto nla_put_failure;
516	return skb->len;
517
518nla_put_failure:
519	return -1;
520}
521
522static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
 
523{
524	int prio;
525	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 
526
527	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
528		skb_queue_head_init(band2list(priv, prio));
 
 
 
 
 
 
 
 
 
 
529
530	/* Can by-pass the queue discipline */
531	qdisc->flags |= TCQ_F_CAN_BYPASS;
532	return 0;
533}
534
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
535struct Qdisc_ops pfifo_fast_ops __read_mostly = {
536	.id		=	"pfifo_fast",
537	.priv_size	=	sizeof(struct pfifo_fast_priv),
538	.enqueue	=	pfifo_fast_enqueue,
539	.dequeue	=	pfifo_fast_dequeue,
540	.peek		=	pfifo_fast_peek,
541	.init		=	pfifo_fast_init,
 
542	.reset		=	pfifo_fast_reset,
543	.dump		=	pfifo_fast_dump,
 
544	.owner		=	THIS_MODULE,
 
545};
546EXPORT_SYMBOL(pfifo_fast_ops);
547
 
 
 
548struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
549			  struct Qdisc_ops *ops)
 
550{
551	void *p;
552	struct Qdisc *sch;
553	unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
554	int err = -ENOBUFS;
 
555
556	p = kzalloc_node(size, GFP_KERNEL,
557			 netdev_queue_numa_node_read(dev_queue));
 
 
 
 
 
 
558
559	if (!p)
560		goto errout;
561	sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
562	/* if we got non aligned memory, ask more and do alignment ourself */
563	if (sch != p) {
564		kfree(p);
565		p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
566				 netdev_queue_numa_node_read(dev_queue));
567		if (!p)
568			goto errout;
569		sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
570		sch->padded = (char *) sch - (char *) p;
 
 
 
 
 
 
571	}
572	INIT_LIST_HEAD(&sch->list);
573	skb_queue_head_init(&sch->q);
574	spin_lock_init(&sch->busylock);
 
 
 
 
 
 
 
 
 
 
 
 
575	sch->ops = ops;
 
576	sch->enqueue = ops->enqueue;
577	sch->dequeue = ops->dequeue;
578	sch->dev_queue = dev_queue;
579	dev_hold(qdisc_dev(sch));
580	atomic_set(&sch->refcnt, 1);
581
582	return sch;
 
 
583errout:
584	return ERR_PTR(err);
585}
586
587struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
588				struct Qdisc_ops *ops, unsigned int parentid)
 
 
589{
590	struct Qdisc *sch;
591
592	sch = qdisc_alloc(dev_queue, ops);
593	if (IS_ERR(sch))
594		goto errout;
 
 
 
 
 
 
 
595	sch->parent = parentid;
596
597	if (!ops->init || ops->init(sch, NULL) == 0)
 
598		return sch;
 
599
600	qdisc_destroy(sch);
601errout:
602	return NULL;
603}
604EXPORT_SYMBOL(qdisc_create_dflt);
605
606/* Under qdisc_lock(qdisc) and BH! */
607
608void qdisc_reset(struct Qdisc *qdisc)
609{
610	const struct Qdisc_ops *ops = qdisc->ops;
 
 
 
611
612	if (ops->reset)
613		ops->reset(qdisc);
614
615	if (qdisc->gso_skb) {
616		kfree_skb(qdisc->gso_skb);
617		qdisc->gso_skb = NULL;
618		qdisc->q.qlen = 0;
619	}
 
 
 
 
 
 
 
 
620}
621EXPORT_SYMBOL(qdisc_reset);
622
623static void qdisc_rcu_free(struct rcu_head *head)
624{
625	struct Qdisc *qdisc = container_of(head, struct Qdisc, rcu_head);
 
 
 
626
627	kfree((char *) qdisc - qdisc->padded);
628}
629
630void qdisc_destroy(struct Qdisc *qdisc)
631{
632	const struct Qdisc_ops  *ops = qdisc->ops;
633
634	if (qdisc->flags & TCQ_F_BUILTIN ||
635	    !atomic_dec_and_test(&qdisc->refcnt))
636		return;
 
 
 
637
638#ifdef CONFIG_NET_SCHED
639	qdisc_list_del(qdisc);
640
641	qdisc_put_stab(rtnl_dereference(qdisc->stab));
642#endif
643	gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
644	if (ops->reset)
645		ops->reset(qdisc);
 
646	if (ops->destroy)
647		ops->destroy(qdisc);
648
649	module_put(ops->owner);
650	dev_put(qdisc_dev(qdisc));
651
652	kfree_skb(qdisc->gso_skb);
653	/*
654	 * gen_estimator est_timer() might access qdisc->q.lock,
655	 * wait a RCU grace period before freeing qdisc.
656	 */
657	call_rcu(&qdisc->rcu_head, qdisc_rcu_free);
658}
659EXPORT_SYMBOL(qdisc_destroy);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
660
661/* Attach toplevel qdisc to device queue. */
662struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
663			      struct Qdisc *qdisc)
664{
665	struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
666	spinlock_t *root_lock;
667
668	root_lock = qdisc_lock(oqdisc);
669	spin_lock_bh(root_lock);
670
671	/* Prune old scheduler */
672	if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1)
673		qdisc_reset(oqdisc);
674
675	/* ... and graft new one */
676	if (qdisc == NULL)
677		qdisc = &noop_qdisc;
678	dev_queue->qdisc_sleeping = qdisc;
679	rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
680
681	spin_unlock_bh(root_lock);
682
683	return oqdisc;
684}
685EXPORT_SYMBOL(dev_graft_qdisc);
686
687static void attach_one_default_qdisc(struct net_device *dev,
688				     struct netdev_queue *dev_queue,
689				     void *_unused)
690{
691	struct Qdisc *qdisc = &noqueue_qdisc;
 
692
693	if (dev->tx_queue_len) {
694		qdisc = qdisc_create_dflt(dev_queue,
695					  &pfifo_fast_ops, TC_H_ROOT);
696		if (!qdisc) {
697			netdev_info(dev, "activation failed\n");
698			return;
699		}
700	}
 
 
 
701	dev_queue->qdisc_sleeping = qdisc;
702}
703
704static void attach_default_qdiscs(struct net_device *dev)
705{
706	struct netdev_queue *txq;
707	struct Qdisc *qdisc;
708
709	txq = netdev_get_tx_queue(dev, 0);
710
711	if (!netif_is_multiqueue(dev) || dev->tx_queue_len == 0) {
 
712		netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
713		dev->qdisc = txq->qdisc_sleeping;
714		atomic_inc(&dev->qdisc->refcnt);
715	} else {
716		qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT);
717		if (qdisc) {
718			qdisc->ops->attach(qdisc);
719			dev->qdisc = qdisc;
 
720		}
721	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
722}
723
724static void transition_one_qdisc(struct net_device *dev,
725				 struct netdev_queue *dev_queue,
726				 void *_need_watchdog)
727{
728	struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
729	int *need_watchdog_p = _need_watchdog;
730
731	if (!(new_qdisc->flags & TCQ_F_BUILTIN))
732		clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
733
734	rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
735	if (need_watchdog_p && new_qdisc != &noqueue_qdisc) {
736		dev_queue->trans_start = 0;
737		*need_watchdog_p = 1;
738	}
739}
740
741void dev_activate(struct net_device *dev)
742{
743	int need_watchdog;
744
745	/* No queueing discipline is attached to device;
746	   create default one i.e. pfifo_fast for devices,
747	   which need queueing and noqueue_qdisc for
748	   virtual interfaces
749	 */
750
751	if (dev->qdisc == &noop_qdisc)
752		attach_default_qdiscs(dev);
753
754	if (!netif_carrier_ok(dev))
755		/* Delay activation until next carrier-on event */
756		return;
757
758	need_watchdog = 0;
759	netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
760	if (dev_ingress_queue(dev))
761		transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
762
763	if (need_watchdog) {
764		dev->trans_start = jiffies;
765		dev_watchdog_up(dev);
766	}
767}
768EXPORT_SYMBOL(dev_activate);
769
 
 
 
 
 
 
 
 
770static void dev_deactivate_queue(struct net_device *dev,
771				 struct netdev_queue *dev_queue,
772				 void *_qdisc_default)
773{
774	struct Qdisc *qdisc_default = _qdisc_default;
775	struct Qdisc *qdisc;
776
777	qdisc = dev_queue->qdisc;
778	if (qdisc) {
779		spin_lock_bh(qdisc_lock(qdisc));
 
 
 
 
 
 
 
 
 
 
780
781		if (!(qdisc->flags & TCQ_F_BUILTIN))
782			set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
 
783
784		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
785		qdisc_reset(qdisc);
786
787		spin_unlock_bh(qdisc_lock(qdisc));
 
 
 
 
 
 
 
 
 
 
788	}
789}
790
791static bool some_qdisc_is_busy(struct net_device *dev)
792{
793	unsigned int i;
794
795	for (i = 0; i < dev->num_tx_queues; i++) {
796		struct netdev_queue *dev_queue;
797		spinlock_t *root_lock;
798		struct Qdisc *q;
799		int val;
800
801		dev_queue = netdev_get_tx_queue(dev, i);
802		q = dev_queue->qdisc_sleeping;
803		root_lock = qdisc_lock(q);
804
 
805		spin_lock_bh(root_lock);
806
807		val = (qdisc_is_running(q) ||
808		       test_bit(__QDISC_STATE_SCHED, &q->state));
809
810		spin_unlock_bh(root_lock);
811
812		if (val)
813			return true;
814	}
815	return false;
816}
817
818/**
819 * 	dev_deactivate_many - deactivate transmissions on several devices
820 * 	@head: list of devices to deactivate
821 *
822 *	This function returns only when all outstanding transmissions
823 *	have completed, unless all devices are in dismantle phase.
824 */
825void dev_deactivate_many(struct list_head *head)
826{
827	struct net_device *dev;
828	bool sync_needed = false;
829
830	list_for_each_entry(dev, head, unreg_list) {
831		netdev_for_each_tx_queue(dev, dev_deactivate_queue,
832					 &noop_qdisc);
833		if (dev_ingress_queue(dev))
834			dev_deactivate_queue(dev, dev_ingress_queue(dev),
835					     &noop_qdisc);
836
837		dev_watchdog_down(dev);
838		sync_needed |= !dev->dismantle;
839	}
840
841	/* Wait for outstanding qdisc-less dev_queue_xmit calls.
 
842	 * This is avoided if all devices are in dismantle phase :
843	 * Caller will call synchronize_net() for us
844	 */
845	if (sync_needed)
846		synchronize_net();
 
 
 
 
 
 
847
848	/* Wait for outstanding qdisc_run calls. */
849	list_for_each_entry(dev, head, unreg_list)
850		while (some_qdisc_is_busy(dev))
851			yield();
 
 
 
 
 
 
852}
853
854void dev_deactivate(struct net_device *dev)
855{
856	LIST_HEAD(single);
857
858	list_add(&dev->unreg_list, &single);
859	dev_deactivate_many(&single);
860	list_del(&single);
861}
862EXPORT_SYMBOL(dev_deactivate);
863
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
864static void dev_init_scheduler_queue(struct net_device *dev,
865				     struct netdev_queue *dev_queue,
866				     void *_qdisc)
867{
868	struct Qdisc *qdisc = _qdisc;
869
870	dev_queue->qdisc = qdisc;
871	dev_queue->qdisc_sleeping = qdisc;
872}
873
874void dev_init_scheduler(struct net_device *dev)
875{
876	dev->qdisc = &noop_qdisc;
877	netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
878	if (dev_ingress_queue(dev))
879		dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
880
881	setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
882}
883
884static void shutdown_scheduler_queue(struct net_device *dev,
885				     struct netdev_queue *dev_queue,
886				     void *_qdisc_default)
887{
888	struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
889	struct Qdisc *qdisc_default = _qdisc_default;
890
891	if (qdisc) {
892		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
893		dev_queue->qdisc_sleeping = qdisc_default;
894
895		qdisc_destroy(qdisc);
896	}
897}
898
899void dev_shutdown(struct net_device *dev)
900{
901	netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
902	if (dev_ingress_queue(dev))
903		shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
904	qdisc_destroy(dev->qdisc);
905	dev->qdisc = &noop_qdisc;
906
907	WARN_ON(timer_pending(&dev->watchdog_timer));
908}