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_tx_queue_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		if (net_ratelimit())
 90			pr_warning("Dead loop on netdevice %s, fix it urgently!\n",
 91				   dev_queue->dev->name);
 92		ret = qdisc_qlen(q);
 93	} else {
 94		/*
 95		 * Another cpu is holding lock, requeue & delay xmits for
 96		 * some time.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 97		 */
 98		__this_cpu_inc(softnet_data.cpu_collision);
 99		ret = dev_requeue_skb(skb, q);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
100	}
 
 
101
102	return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
103}
104
105/*
106 * Transmit one skb, and handle the return status as required. Holding the
107 * __QDISC_STATE_RUNNING bit guarantees that only one CPU can execute this
108 * function.
109 *
110 * Returns to the caller:
111 *				0  - queue is empty or throttled.
112 *				>0 - queue is not empty.
113 */
114int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
115		    struct net_device *dev, struct netdev_queue *txq,
116		    spinlock_t *root_lock)
117{
118	int ret = NETDEV_TX_BUSY;
 
119
120	/* And release qdisc */
121	spin_unlock(root_lock);
 
122
123	HARD_TX_LOCK(dev, txq, smp_processor_id());
124	if (!netif_tx_queue_frozen_or_stopped(txq))
125		ret = dev_hard_start_xmit(skb, dev, txq);
126
127	HARD_TX_UNLOCK(dev, txq);
128
129	spin_lock(root_lock);
130
131	if (dev_xmit_complete(ret)) {
132		/* Driver sent out skb successfully or skb was consumed */
133		ret = qdisc_qlen(q);
134	} else if (ret == NETDEV_TX_LOCKED) {
135		/* Driver try lock failed */
136		ret = handle_dev_cpu_collision(skb, txq, q);
 
 
 
 
 
 
137	} else {
 
 
 
 
 
 
 
 
 
138		/* Driver returned NETDEV_TX_BUSY - requeue skb */
139		if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
140			pr_warning("BUG %s code %d qlen %d\n",
141				   dev->name, ret, q->q.qlen);
142
143		ret = dev_requeue_skb(skb, q);
 
144	}
145
146	if (ret && netif_tx_queue_frozen_or_stopped(txq))
147		ret = 0;
148
149	return ret;
150}
151
152/*
153 * NOTE: Called under qdisc_lock(q) with locally disabled BH.
154 *
155 * __QDISC_STATE_RUNNING guarantees only one CPU can process
156 * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
157 * this queue.
158 *
159 *  netif_tx_lock serializes accesses to device driver.
160 *
161 *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
162 *  if one is grabbed, another must be free.
163 *
164 * Note, that this procedure can be called by a watchdog timer
165 *
166 * Returns to the caller:
167 *				0  - queue is empty or throttled.
168 *				>0 - queue is not empty.
169 *
170 */
171static inline int qdisc_restart(struct Qdisc *q)
172{
 
173	struct netdev_queue *txq;
174	struct net_device *dev;
175	spinlock_t *root_lock;
176	struct sk_buff *skb;
 
177
178	/* Dequeue packet */
179	skb = dequeue_skb(q);
180	if (unlikely(!skb))
181		return 0;
182	WARN_ON_ONCE(skb_dst_is_noref(skb));
183	root_lock = qdisc_lock(q);
 
 
184	dev = qdisc_dev(q);
185	txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
186
187	return sch_direct_xmit(skb, q, dev, txq, root_lock);
188}
189
190void __qdisc_run(struct Qdisc *q)
191{
192	int quota = weight_p;
 
193
194	while (qdisc_restart(q)) {
195		/*
196		 * Ordered by possible occurrence: Postpone processing if
197		 * 1. we've exceeded packet quota
198		 * 2. another process needs the CPU;
199		 */
200		if (--quota <= 0 || need_resched()) {
201			__netif_schedule(q);
202			break;
203		}
204	}
205
206	qdisc_run_end(q);
207}
208
209unsigned long dev_trans_start(struct net_device *dev)
210{
211	unsigned long val, res = dev->trans_start;
212	unsigned int i;
213
214	for (i = 0; i < dev->num_tx_queues; i++) {
 
 
 
 
 
215		val = netdev_get_tx_queue(dev, i)->trans_start;
216		if (val && time_after(val, res))
217			res = val;
218	}
219	dev->trans_start = res;
220	return res;
221}
222EXPORT_SYMBOL(dev_trans_start);
223
224static void dev_watchdog(unsigned long arg)
225{
226	struct net_device *dev = (struct net_device *)arg;
227
228	netif_tx_lock(dev);
229	if (!qdisc_tx_is_noop(dev)) {
230		if (netif_device_present(dev) &&
231		    netif_running(dev) &&
232		    netif_carrier_ok(dev)) {
233			int some_queue_timedout = 0;
234			unsigned int i;
235			unsigned long trans_start;
236
237			for (i = 0; i < dev->num_tx_queues; i++) {
238				struct netdev_queue *txq;
239
240				txq = netdev_get_tx_queue(dev, i);
241				/*
242				 * old device drivers set dev->trans_start
243				 */
244				trans_start = txq->trans_start ? : dev->trans_start;
245				if (netif_tx_queue_stopped(txq) &&
246				    time_after(jiffies, (trans_start +
247							 dev->watchdog_timeo))) {
248					some_queue_timedout = 1;
 
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	NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 
515	return skb->len;
516
517nla_put_failure:
518	return -1;
519}
520
521static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
 
522{
523	int prio;
524	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 
525
526	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
527		skb_queue_head_init(band2list(priv, prio));
 
 
 
 
 
 
 
 
 
 
528
529	/* Can by-pass the queue discipline */
530	qdisc->flags |= TCQ_F_CAN_BYPASS;
531	return 0;
532}
533
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
534struct Qdisc_ops pfifo_fast_ops __read_mostly = {
535	.id		=	"pfifo_fast",
536	.priv_size	=	sizeof(struct pfifo_fast_priv),
537	.enqueue	=	pfifo_fast_enqueue,
538	.dequeue	=	pfifo_fast_dequeue,
539	.peek		=	pfifo_fast_peek,
540	.init		=	pfifo_fast_init,
 
541	.reset		=	pfifo_fast_reset,
542	.dump		=	pfifo_fast_dump,
 
543	.owner		=	THIS_MODULE,
 
544};
545EXPORT_SYMBOL(pfifo_fast_ops);
546
 
 
 
547struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
548			  struct Qdisc_ops *ops)
 
549{
550	void *p;
551	struct Qdisc *sch;
552	unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
553	int err = -ENOBUFS;
 
554
 
 
 
 
 
 
 
555	p = kzalloc_node(size, GFP_KERNEL,
556			 netdev_queue_numa_node_read(dev_queue));
557
558	if (!p)
559		goto errout;
560	sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
561	/* if we got non aligned memory, ask more and do alignment ourself */
562	if (sch != p) {
563		kfree(p);
564		p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
565				 netdev_queue_numa_node_read(dev_queue));
566		if (!p)
567			goto errout;
568		sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
569		sch->padded = (char *) sch - (char *) p;
570	}
571	INIT_LIST_HEAD(&sch->list);
572	skb_queue_head_init(&sch->q);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
573	spin_lock_init(&sch->busylock);
 
 
 
 
 
 
 
 
 
 
 
 
574	sch->ops = ops;
 
575	sch->enqueue = ops->enqueue;
576	sch->dequeue = ops->dequeue;
577	sch->dev_queue = dev_queue;
578	dev_hold(qdisc_dev(sch));
579	atomic_set(&sch->refcnt, 1);
 
580
581	return sch;
 
 
582errout:
583	return ERR_PTR(err);
584}
585
586struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
587				struct Qdisc_ops *ops, unsigned int parentid)
 
 
588{
589	struct Qdisc *sch;
590
591	sch = qdisc_alloc(dev_queue, ops);
592	if (IS_ERR(sch))
593		goto errout;
 
 
 
 
 
 
 
594	sch->parent = parentid;
595
596	if (!ops->init || ops->init(sch, NULL) == 0)
 
597		return sch;
 
598
599	qdisc_destroy(sch);
600errout:
601	return NULL;
602}
603EXPORT_SYMBOL(qdisc_create_dflt);
604
605/* Under qdisc_lock(qdisc) and BH! */
606
607void qdisc_reset(struct Qdisc *qdisc)
608{
609	const struct Qdisc_ops *ops = qdisc->ops;
 
 
 
610
611	if (ops->reset)
612		ops->reset(qdisc);
613
614	if (qdisc->gso_skb) {
615		kfree_skb(qdisc->gso_skb);
616		qdisc->gso_skb = NULL;
617		qdisc->q.qlen = 0;
618	}
 
 
 
 
 
 
 
 
619}
620EXPORT_SYMBOL(qdisc_reset);
621
622static void qdisc_rcu_free(struct rcu_head *head)
623{
624	struct Qdisc *qdisc = container_of(head, struct Qdisc, rcu_head);
 
 
 
625
626	kfree((char *) qdisc - qdisc->padded);
627}
628
629void qdisc_destroy(struct Qdisc *qdisc)
630{
631	const struct Qdisc_ops  *ops = qdisc->ops;
632
633	if (qdisc->flags & TCQ_F_BUILTIN ||
634	    !atomic_dec_and_test(&qdisc->refcnt))
635		return;
 
 
 
636
637#ifdef CONFIG_NET_SCHED
638	qdisc_list_del(qdisc);
639
640	qdisc_put_stab(rtnl_dereference(qdisc->stab));
641#endif
642	gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
643	if (ops->reset)
644		ops->reset(qdisc);
 
645	if (ops->destroy)
646		ops->destroy(qdisc);
647
648	module_put(ops->owner);
649	dev_put(qdisc_dev(qdisc));
650
651	kfree_skb(qdisc->gso_skb);
652	/*
653	 * gen_estimator est_timer() might access qdisc->q.lock,
654	 * wait a RCU grace period before freeing qdisc.
655	 */
656	call_rcu(&qdisc->rcu_head, qdisc_rcu_free);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
657}
658EXPORT_SYMBOL(qdisc_destroy);
659
660/* Attach toplevel qdisc to device queue. */
661struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
662			      struct Qdisc *qdisc)
663{
664	struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
665	spinlock_t *root_lock;
666
667	root_lock = qdisc_lock(oqdisc);
668	spin_lock_bh(root_lock);
669
670	/* Prune old scheduler */
671	if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1)
672		qdisc_reset(oqdisc);
673
674	/* ... and graft new one */
675	if (qdisc == NULL)
676		qdisc = &noop_qdisc;
677	dev_queue->qdisc_sleeping = qdisc;
678	rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
679
680	spin_unlock_bh(root_lock);
681
682	return oqdisc;
683}
684EXPORT_SYMBOL(dev_graft_qdisc);
685
686static void attach_one_default_qdisc(struct net_device *dev,
687				     struct netdev_queue *dev_queue,
688				     void *_unused)
689{
690	struct Qdisc *qdisc = &noqueue_qdisc;
 
691
692	if (dev->tx_queue_len) {
693		qdisc = qdisc_create_dflt(dev_queue,
694					  &pfifo_fast_ops, TC_H_ROOT);
695		if (!qdisc) {
696			netdev_info(dev, "activation failed\n");
697			return;
698		}
699	}
 
 
 
700	dev_queue->qdisc_sleeping = qdisc;
701}
702
703static void attach_default_qdiscs(struct net_device *dev)
704{
705	struct netdev_queue *txq;
706	struct Qdisc *qdisc;
707
708	txq = netdev_get_tx_queue(dev, 0);
709
710	if (!netif_is_multiqueue(dev) || dev->tx_queue_len == 0) {
 
711		netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
712		dev->qdisc = txq->qdisc_sleeping;
713		atomic_inc(&dev->qdisc->refcnt);
714	} else {
715		qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT);
716		if (qdisc) {
717			qdisc->ops->attach(qdisc);
718			dev->qdisc = qdisc;
 
719		}
720	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
721}
722
723static void transition_one_qdisc(struct net_device *dev,
724				 struct netdev_queue *dev_queue,
725				 void *_need_watchdog)
726{
727	struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
728	int *need_watchdog_p = _need_watchdog;
729
730	if (!(new_qdisc->flags & TCQ_F_BUILTIN))
731		clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
732
733	rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
734	if (need_watchdog_p && new_qdisc != &noqueue_qdisc) {
735		dev_queue->trans_start = 0;
736		*need_watchdog_p = 1;
737	}
738}
739
740void dev_activate(struct net_device *dev)
741{
742	int need_watchdog;
743
744	/* No queueing discipline is attached to device;
745	   create default one i.e. pfifo_fast for devices,
746	   which need queueing and noqueue_qdisc for
747	   virtual interfaces
748	 */
749
750	if (dev->qdisc == &noop_qdisc)
751		attach_default_qdiscs(dev);
752
753	if (!netif_carrier_ok(dev))
754		/* Delay activation until next carrier-on event */
755		return;
756
757	need_watchdog = 0;
758	netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
759	if (dev_ingress_queue(dev))
760		transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
761
762	if (need_watchdog) {
763		dev->trans_start = jiffies;
764		dev_watchdog_up(dev);
765	}
766}
767EXPORT_SYMBOL(dev_activate);
768
 
 
 
 
 
 
 
 
769static void dev_deactivate_queue(struct net_device *dev,
770				 struct netdev_queue *dev_queue,
771				 void *_qdisc_default)
772{
773	struct Qdisc *qdisc_default = _qdisc_default;
774	struct Qdisc *qdisc;
775
776	qdisc = dev_queue->qdisc;
777	if (qdisc) {
778		spin_lock_bh(qdisc_lock(qdisc));
 
 
 
779
780		if (!(qdisc->flags & TCQ_F_BUILTIN))
781			set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
 
 
 
 
782
783		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
784		qdisc_reset(qdisc);
 
785
786		spin_unlock_bh(qdisc_lock(qdisc));
787	}
 
 
 
 
 
 
 
 
 
788}
789
790static bool some_qdisc_is_busy(struct net_device *dev)
791{
792	unsigned int i;
793
794	for (i = 0; i < dev->num_tx_queues; i++) {
795		struct netdev_queue *dev_queue;
796		spinlock_t *root_lock;
797		struct Qdisc *q;
798		int val;
799
800		dev_queue = netdev_get_tx_queue(dev, i);
801		q = dev_queue->qdisc_sleeping;
802		root_lock = qdisc_lock(q);
803
 
804		spin_lock_bh(root_lock);
805
806		val = (qdisc_is_running(q) ||
807		       test_bit(__QDISC_STATE_SCHED, &q->state));
808
809		spin_unlock_bh(root_lock);
810
811		if (val)
812			return true;
813	}
814	return false;
815}
816
817/**
818 * 	dev_deactivate_many - deactivate transmissions on several devices
819 * 	@head: list of devices to deactivate
820 *
821 *	This function returns only when all outstanding transmissions
822 *	have completed, unless all devices are in dismantle phase.
823 */
824void dev_deactivate_many(struct list_head *head)
825{
826	struct net_device *dev;
827	bool sync_needed = false;
828
829	list_for_each_entry(dev, head, unreg_list) {
830		netdev_for_each_tx_queue(dev, dev_deactivate_queue,
831					 &noop_qdisc);
832		if (dev_ingress_queue(dev))
833			dev_deactivate_queue(dev, dev_ingress_queue(dev),
834					     &noop_qdisc);
835
836		dev_watchdog_down(dev);
837		sync_needed |= !dev->dismantle;
838	}
839
840	/* Wait for outstanding qdisc-less dev_queue_xmit calls.
 
841	 * This is avoided if all devices are in dismantle phase :
842	 * Caller will call synchronize_net() for us
843	 */
844	if (sync_needed)
845		synchronize_net();
 
 
 
 
 
 
846
847	/* Wait for outstanding qdisc_run calls. */
848	list_for_each_entry(dev, head, unreg_list)
849		while (some_qdisc_is_busy(dev))
850			yield();
 
 
 
 
 
 
851}
852
853void dev_deactivate(struct net_device *dev)
854{
855	LIST_HEAD(single);
856
857	list_add(&dev->unreg_list, &single);
858	dev_deactivate_many(&single);
859	list_del(&single);
860}
861EXPORT_SYMBOL(dev_deactivate);
862
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
863static void dev_init_scheduler_queue(struct net_device *dev,
864				     struct netdev_queue *dev_queue,
865				     void *_qdisc)
866{
867	struct Qdisc *qdisc = _qdisc;
868
869	dev_queue->qdisc = qdisc;
870	dev_queue->qdisc_sleeping = qdisc;
871}
872
873void dev_init_scheduler(struct net_device *dev)
874{
875	dev->qdisc = &noop_qdisc;
876	netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
877	if (dev_ingress_queue(dev))
878		dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
879
880	setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
881}
882
883static void shutdown_scheduler_queue(struct net_device *dev,
884				     struct netdev_queue *dev_queue,
885				     void *_qdisc_default)
886{
887	struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
888	struct Qdisc *qdisc_default = _qdisc_default;
889
890	if (qdisc) {
891		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
892		dev_queue->qdisc_sleeping = qdisc_default;
893
894		qdisc_destroy(qdisc);
895	}
896}
897
898void dev_shutdown(struct net_device *dev)
899{
900	netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
901	if (dev_ingress_queue(dev))
902		shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
903	qdisc_destroy(dev->qdisc);
904	dev->qdisc = &noop_qdisc;
905
906	WARN_ON(timer_pending(&dev->watchdog_timer));
907}