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 
dev_requeue_skb(struct sk_buff * skb,struct Qdisc * q)42 static 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 
dequeue_skb(struct Qdisc * q)53 static 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 
handle_dev_cpu_collision(struct sk_buff * skb,struct netdev_queue * dev_queue,struct Qdisc * q)75 static 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  */
sch_direct_xmit(struct sk_buff * skb,struct Qdisc * q,struct net_device * dev,struct netdev_queue * txq,spinlock_t * root_lock)114 int 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_xmit_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_xmit_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  */
qdisc_restart(struct Qdisc * q)171 static 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 
__qdisc_run(struct Qdisc * q)190 void __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 
dev_trans_start(struct net_device * dev)209 unsigned 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 }
222 EXPORT_SYMBOL(dev_trans_start);
223 
dev_watchdog(unsigned long arg)224 static 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_xmit_stopped(txq) &&
246 				    time_after(jiffies, (trans_start +
247 							 dev->watchdog_timeo))) {
248 					some_queue_timedout = 1;
249 					txq->trans_timeout++;
250 					break;
251 				}
252 			}
253 
254 			if (some_queue_timedout) {
255 				WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
256 				       dev->name, netdev_drivername(dev), i);
257 				dev->netdev_ops->ndo_tx_timeout(dev);
258 			}
259 			if (!mod_timer(&dev->watchdog_timer,
260 				       round_jiffies(jiffies +
261 						     dev->watchdog_timeo)))
262 				dev_hold(dev);
263 		}
264 	}
265 	netif_tx_unlock(dev);
266 
267 	dev_put(dev);
268 }
269 
__netdev_watchdog_up(struct net_device * dev)270 void __netdev_watchdog_up(struct net_device *dev)
271 {
272 	if (dev->netdev_ops->ndo_tx_timeout) {
273 		if (dev->watchdog_timeo <= 0)
274 			dev->watchdog_timeo = 5*HZ;
275 		if (!mod_timer(&dev->watchdog_timer,
276 			       round_jiffies(jiffies + dev->watchdog_timeo)))
277 			dev_hold(dev);
278 	}
279 }
280 
dev_watchdog_up(struct net_device * dev)281 static void dev_watchdog_up(struct net_device *dev)
282 {
283 	__netdev_watchdog_up(dev);
284 }
285 
dev_watchdog_down(struct net_device * dev)286 static void dev_watchdog_down(struct net_device *dev)
287 {
288 	netif_tx_lock_bh(dev);
289 	if (del_timer(&dev->watchdog_timer))
290 		dev_put(dev);
291 	netif_tx_unlock_bh(dev);
292 }
293 
294 /**
295  *	netif_carrier_on - set carrier
296  *	@dev: network device
297  *
298  * Device has detected that carrier.
299  */
netif_carrier_on(struct net_device * dev)300 void netif_carrier_on(struct net_device *dev)
301 {
302 	if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
303 		if (dev->reg_state == NETREG_UNINITIALIZED)
304 			return;
305 		linkwatch_fire_event(dev);
306 		if (netif_running(dev))
307 			__netdev_watchdog_up(dev);
308 	}
309 }
310 EXPORT_SYMBOL(netif_carrier_on);
311 
312 /**
313  *	netif_carrier_off - clear carrier
314  *	@dev: network device
315  *
316  * Device has detected loss of carrier.
317  */
netif_carrier_off(struct net_device * dev)318 void netif_carrier_off(struct net_device *dev)
319 {
320 	if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
321 		if (dev->reg_state == NETREG_UNINITIALIZED)
322 			return;
323 		linkwatch_fire_event(dev);
324 	}
325 }
326 EXPORT_SYMBOL(netif_carrier_off);
327 
328 /**
329  * 	netif_notify_peers - notify network peers about existence of @dev
330  * 	@dev: network device
331  *
332  * Generate traffic such that interested network peers are aware of
333  * @dev, such as by generating a gratuitous ARP. This may be used when
334  * a device wants to inform the rest of the network about some sort of
335  * reconfiguration such as a failover event or virtual machine
336  * migration.
337  */
netif_notify_peers(struct net_device * dev)338 void netif_notify_peers(struct net_device *dev)
339 {
340 	rtnl_lock();
341 	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
342 	rtnl_unlock();
343 }
344 EXPORT_SYMBOL(netif_notify_peers);
345 
346 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
347    under all circumstances. It is difficult to invent anything faster or
348    cheaper.
349  */
350 
noop_enqueue(struct sk_buff * skb,struct Qdisc * qdisc)351 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
352 {
353 	kfree_skb(skb);
354 	return NET_XMIT_CN;
355 }
356 
noop_dequeue(struct Qdisc * qdisc)357 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
358 {
359 	return NULL;
360 }
361 
362 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
363 	.id		=	"noop",
364 	.priv_size	=	0,
365 	.enqueue	=	noop_enqueue,
366 	.dequeue	=	noop_dequeue,
367 	.peek		=	noop_dequeue,
368 	.owner		=	THIS_MODULE,
369 };
370 
371 static struct netdev_queue noop_netdev_queue = {
372 	.qdisc		=	&noop_qdisc,
373 	.qdisc_sleeping	=	&noop_qdisc,
374 };
375 
376 struct Qdisc noop_qdisc = {
377 	.enqueue	=	noop_enqueue,
378 	.dequeue	=	noop_dequeue,
379 	.flags		=	TCQ_F_BUILTIN,
380 	.ops		=	&noop_qdisc_ops,
381 	.list		=	LIST_HEAD_INIT(noop_qdisc.list),
382 	.q.lock		=	__SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
383 	.dev_queue	=	&noop_netdev_queue,
384 	.busylock	=	__SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
385 };
386 EXPORT_SYMBOL(noop_qdisc);
387 
388 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
389 	.id		=	"noqueue",
390 	.priv_size	=	0,
391 	.enqueue	=	noop_enqueue,
392 	.dequeue	=	noop_dequeue,
393 	.peek		=	noop_dequeue,
394 	.owner		=	THIS_MODULE,
395 };
396 
397 static struct Qdisc noqueue_qdisc;
398 static struct netdev_queue noqueue_netdev_queue = {
399 	.qdisc		=	&noqueue_qdisc,
400 	.qdisc_sleeping	=	&noqueue_qdisc,
401 };
402 
403 static struct Qdisc noqueue_qdisc = {
404 	.enqueue	=	NULL,
405 	.dequeue	=	noop_dequeue,
406 	.flags		=	TCQ_F_BUILTIN,
407 	.ops		=	&noqueue_qdisc_ops,
408 	.list		=	LIST_HEAD_INIT(noqueue_qdisc.list),
409 	.q.lock		=	__SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
410 	.dev_queue	=	&noqueue_netdev_queue,
411 	.busylock	=	__SPIN_LOCK_UNLOCKED(noqueue_qdisc.busylock),
412 };
413 
414 
415 static const u8 prio2band[TC_PRIO_MAX + 1] = {
416 	1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
417 };
418 
419 /* 3-band FIFO queue: old style, but should be a bit faster than
420    generic prio+fifo combination.
421  */
422 
423 #define PFIFO_FAST_BANDS 3
424 
425 /*
426  * Private data for a pfifo_fast scheduler containing:
427  * 	- queues for the three band
428  * 	- bitmap indicating which of the bands contain skbs
429  */
430 struct pfifo_fast_priv {
431 	u32 bitmap;
432 	struct sk_buff_head q[PFIFO_FAST_BANDS];
433 };
434 
435 /*
436  * Convert a bitmap to the first band number where an skb is queued, where:
437  * 	bitmap=0 means there are no skbs on any band.
438  * 	bitmap=1 means there is an skb on band 0.
439  *	bitmap=7 means there are skbs on all 3 bands, etc.
440  */
441 static const int bitmap2band[] = {-1, 0, 1, 0, 2, 0, 1, 0};
442 
band2list(struct pfifo_fast_priv * priv,int band)443 static inline struct sk_buff_head *band2list(struct pfifo_fast_priv *priv,
444 					     int band)
445 {
446 	return priv->q + band;
447 }
448 
pfifo_fast_enqueue(struct sk_buff * skb,struct Qdisc * qdisc)449 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc)
450 {
451 	if (skb_queue_len(&qdisc->q) < qdisc_dev(qdisc)->tx_queue_len) {
452 		int band = prio2band[skb->priority & TC_PRIO_MAX];
453 		struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
454 		struct sk_buff_head *list = band2list(priv, band);
455 
456 		priv->bitmap |= (1 << band);
457 		qdisc->q.qlen++;
458 		return __qdisc_enqueue_tail(skb, qdisc, list);
459 	}
460 
461 	return qdisc_drop(skb, qdisc);
462 }
463 
pfifo_fast_dequeue(struct Qdisc * qdisc)464 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
465 {
466 	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
467 	int band = bitmap2band[priv->bitmap];
468 
469 	if (likely(band >= 0)) {
470 		struct sk_buff_head *list = band2list(priv, band);
471 		struct sk_buff *skb = __qdisc_dequeue_head(qdisc, list);
472 
473 		qdisc->q.qlen--;
474 		if (skb_queue_empty(list))
475 			priv->bitmap &= ~(1 << band);
476 
477 		return skb;
478 	}
479 
480 	return NULL;
481 }
482 
pfifo_fast_peek(struct Qdisc * qdisc)483 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
484 {
485 	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
486 	int band = bitmap2band[priv->bitmap];
487 
488 	if (band >= 0) {
489 		struct sk_buff_head *list = band2list(priv, band);
490 
491 		return skb_peek(list);
492 	}
493 
494 	return NULL;
495 }
496 
pfifo_fast_reset(struct Qdisc * qdisc)497 static void pfifo_fast_reset(struct Qdisc *qdisc)
498 {
499 	int prio;
500 	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
501 
502 	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
503 		__qdisc_reset_queue(qdisc, band2list(priv, prio));
504 
505 	priv->bitmap = 0;
506 	qdisc->qstats.backlog = 0;
507 	qdisc->q.qlen = 0;
508 }
509 
pfifo_fast_dump(struct Qdisc * qdisc,struct sk_buff * skb)510 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
511 {
512 	struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
513 
514 	memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
515 	NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
516 	return skb->len;
517 
518 nla_put_failure:
519 	return -1;
520 }
521 
pfifo_fast_init(struct Qdisc * qdisc,struct nlattr * opt)522 static 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 
535 struct 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 };
546 EXPORT_SYMBOL(pfifo_fast_ops);
547 
qdisc_alloc(struct netdev_queue * dev_queue,struct Qdisc_ops * ops)548 struct 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;
583 errout:
584 	return ERR_PTR(err);
585 }
586 
qdisc_create_dflt(struct netdev_queue * dev_queue,struct Qdisc_ops * ops,unsigned int parentid)587 struct 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);
601 errout:
602 	return NULL;
603 }
604 EXPORT_SYMBOL(qdisc_create_dflt);
605 
606 /* Under qdisc_lock(qdisc) and BH! */
607 
qdisc_reset(struct Qdisc * qdisc)608 void 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 }
621 EXPORT_SYMBOL(qdisc_reset);
622 
qdisc_rcu_free(struct rcu_head * head)623 static 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 
qdisc_destroy(struct Qdisc * qdisc)630 void 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 }
659 EXPORT_SYMBOL(qdisc_destroy);
660 
661 /* Attach toplevel qdisc to device queue. */
dev_graft_qdisc(struct netdev_queue * dev_queue,struct Qdisc * qdisc)662 struct 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 }
685 EXPORT_SYMBOL(dev_graft_qdisc);
686 
attach_one_default_qdisc(struct net_device * dev,struct netdev_queue * dev_queue,void * _unused)687 static 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 
attach_default_qdiscs(struct net_device * dev)704 static 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 
transition_one_qdisc(struct net_device * dev,struct netdev_queue * dev_queue,void * _need_watchdog)724 static 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 
dev_activate(struct net_device * dev)741 void 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 }
768 EXPORT_SYMBOL(dev_activate);
769 
dev_deactivate_queue(struct net_device * dev,struct netdev_queue * dev_queue,void * _qdisc_default)770 static 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 
some_qdisc_is_busy(struct net_device * dev)791 static 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  */
dev_deactivate_many(struct list_head * head)825 void 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 
dev_deactivate(struct net_device * dev)854 void 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 }
862 EXPORT_SYMBOL(dev_deactivate);
863 
dev_init_scheduler_queue(struct net_device * dev,struct netdev_queue * dev_queue,void * _qdisc)864 static 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 
dev_init_scheduler(struct net_device * dev)874 void 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 
shutdown_scheduler_queue(struct net_device * dev,struct netdev_queue * dev_queue,void * _qdisc_default)884 static 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 
dev_shutdown(struct net_device * dev)899 void 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 }
909