xref: /linux/include/net/sch_generic.h (revision bb1c928df78ee6e3665a0d013e74108cc9abf34b)
1 #ifndef __NET_SCHED_GENERIC_H
2 #define __NET_SCHED_GENERIC_H
3 
4 #include <linux/netdevice.h>
5 #include <linux/types.h>
6 #include <linux/rcupdate.h>
7 #include <linux/pkt_sched.h>
8 #include <linux/pkt_cls.h>
9 #include <linux/percpu.h>
10 #include <linux/dynamic_queue_limits.h>
11 #include <linux/list.h>
12 #include <linux/refcount.h>
13 #include <net/gen_stats.h>
14 #include <net/rtnetlink.h>
15 
16 struct Qdisc_ops;
17 struct qdisc_walker;
18 struct tcf_walker;
19 struct module;
20 
21 struct qdisc_rate_table {
22 	struct tc_ratespec rate;
23 	u32		data[256];
24 	struct qdisc_rate_table *next;
25 	int		refcnt;
26 };
27 
28 enum qdisc_state_t {
29 	__QDISC_STATE_SCHED,
30 	__QDISC_STATE_DEACTIVATED,
31 };
32 
33 struct qdisc_size_table {
34 	struct rcu_head		rcu;
35 	struct list_head	list;
36 	struct tc_sizespec	szopts;
37 	int			refcnt;
38 	u16			data[];
39 };
40 
41 /* similar to sk_buff_head, but skb->prev pointer is undefined. */
42 struct qdisc_skb_head {
43 	struct sk_buff	*head;
44 	struct sk_buff	*tail;
45 	__u32		qlen;
46 	spinlock_t	lock;
47 };
48 
49 struct Qdisc {
50 	int 			(*enqueue)(struct sk_buff *skb,
51 					   struct Qdisc *sch,
52 					   struct sk_buff **to_free);
53 	struct sk_buff *	(*dequeue)(struct Qdisc *sch);
54 	unsigned int		flags;
55 #define TCQ_F_BUILTIN		1
56 #define TCQ_F_INGRESS		2
57 #define TCQ_F_CAN_BYPASS	4
58 #define TCQ_F_MQROOT		8
59 #define TCQ_F_ONETXQUEUE	0x10 /* dequeue_skb() can assume all skbs are for
60 				      * q->dev_queue : It can test
61 				      * netif_xmit_frozen_or_stopped() before
62 				      * dequeueing next packet.
63 				      * Its true for MQ/MQPRIO slaves, or non
64 				      * multiqueue device.
65 				      */
66 #define TCQ_F_WARN_NONWC	(1 << 16)
67 #define TCQ_F_CPUSTATS		0x20 /* run using percpu statistics */
68 #define TCQ_F_NOPARENT		0x40 /* root of its hierarchy :
69 				      * qdisc_tree_decrease_qlen() should stop.
70 				      */
71 #define TCQ_F_INVISIBLE		0x80 /* invisible by default in dump */
72 	u32			limit;
73 	const struct Qdisc_ops	*ops;
74 	struct qdisc_size_table	__rcu *stab;
75 	struct hlist_node       hash;
76 	u32			handle;
77 	u32			parent;
78 	void			*u32_node;
79 
80 	struct netdev_queue	*dev_queue;
81 
82 	struct net_rate_estimator __rcu *rate_est;
83 	struct gnet_stats_basic_cpu __percpu *cpu_bstats;
84 	struct gnet_stats_queue	__percpu *cpu_qstats;
85 
86 	/*
87 	 * For performance sake on SMP, we put highly modified fields at the end
88 	 */
89 	struct sk_buff		*gso_skb ____cacheline_aligned_in_smp;
90 	struct qdisc_skb_head	q;
91 	struct gnet_stats_basic_packed bstats;
92 	seqcount_t		running;
93 	struct gnet_stats_queue	qstats;
94 	unsigned long		state;
95 	struct Qdisc            *next_sched;
96 	struct sk_buff		*skb_bad_txq;
97 	struct rcu_head		rcu_head;
98 	int			padded;
99 	refcount_t		refcnt;
100 
101 	spinlock_t		busylock ____cacheline_aligned_in_smp;
102 };
103 
104 static inline bool qdisc_is_running(const struct Qdisc *qdisc)
105 {
106 	return (raw_read_seqcount(&qdisc->running) & 1) ? true : false;
107 }
108 
109 static inline bool qdisc_run_begin(struct Qdisc *qdisc)
110 {
111 	if (qdisc_is_running(qdisc))
112 		return false;
113 	/* Variant of write_seqcount_begin() telling lockdep a trylock
114 	 * was attempted.
115 	 */
116 	raw_write_seqcount_begin(&qdisc->running);
117 	seqcount_acquire(&qdisc->running.dep_map, 0, 1, _RET_IP_);
118 	return true;
119 }
120 
121 static inline void qdisc_run_end(struct Qdisc *qdisc)
122 {
123 	write_seqcount_end(&qdisc->running);
124 }
125 
126 static inline bool qdisc_may_bulk(const struct Qdisc *qdisc)
127 {
128 	return qdisc->flags & TCQ_F_ONETXQUEUE;
129 }
130 
131 static inline int qdisc_avail_bulklimit(const struct netdev_queue *txq)
132 {
133 #ifdef CONFIG_BQL
134 	/* Non-BQL migrated drivers will return 0, too. */
135 	return dql_avail(&txq->dql);
136 #else
137 	return 0;
138 #endif
139 }
140 
141 struct Qdisc_class_ops {
142 	/* Child qdisc manipulation */
143 	struct netdev_queue *	(*select_queue)(struct Qdisc *, struct tcmsg *);
144 	int			(*graft)(struct Qdisc *, unsigned long cl,
145 					struct Qdisc *, struct Qdisc **);
146 	struct Qdisc *		(*leaf)(struct Qdisc *, unsigned long cl);
147 	void			(*qlen_notify)(struct Qdisc *, unsigned long);
148 
149 	/* Class manipulation routines */
150 	unsigned long		(*get)(struct Qdisc *, u32 classid);
151 	void			(*put)(struct Qdisc *, unsigned long);
152 	int			(*change)(struct Qdisc *, u32, u32,
153 					struct nlattr **, unsigned long *);
154 	int			(*delete)(struct Qdisc *, unsigned long);
155 	void			(*walk)(struct Qdisc *, struct qdisc_walker * arg);
156 
157 	/* Filter manipulation */
158 	struct tcf_block *	(*tcf_block)(struct Qdisc *, unsigned long);
159 	bool			(*tcf_cl_offload)(u32 classid);
160 	unsigned long		(*bind_tcf)(struct Qdisc *, unsigned long,
161 					u32 classid);
162 	void			(*unbind_tcf)(struct Qdisc *, unsigned long);
163 
164 	/* rtnetlink specific */
165 	int			(*dump)(struct Qdisc *, unsigned long,
166 					struct sk_buff *skb, struct tcmsg*);
167 	int			(*dump_stats)(struct Qdisc *, unsigned long,
168 					struct gnet_dump *);
169 };
170 
171 struct Qdisc_ops {
172 	struct Qdisc_ops	*next;
173 	const struct Qdisc_class_ops	*cl_ops;
174 	char			id[IFNAMSIZ];
175 	int			priv_size;
176 
177 	int 			(*enqueue)(struct sk_buff *skb,
178 					   struct Qdisc *sch,
179 					   struct sk_buff **to_free);
180 	struct sk_buff *	(*dequeue)(struct Qdisc *);
181 	struct sk_buff *	(*peek)(struct Qdisc *);
182 
183 	int			(*init)(struct Qdisc *, struct nlattr *arg);
184 	void			(*reset)(struct Qdisc *);
185 	void			(*destroy)(struct Qdisc *);
186 	int			(*change)(struct Qdisc *, struct nlattr *arg);
187 	void			(*attach)(struct Qdisc *);
188 
189 	int			(*dump)(struct Qdisc *, struct sk_buff *);
190 	int			(*dump_stats)(struct Qdisc *, struct gnet_dump *);
191 
192 	struct module		*owner;
193 };
194 
195 
196 struct tcf_result {
197 	union {
198 		struct {
199 			unsigned long	class;
200 			u32		classid;
201 		};
202 		const struct tcf_proto *goto_tp;
203 	};
204 };
205 
206 struct tcf_proto_ops {
207 	struct list_head	head;
208 	char			kind[IFNAMSIZ];
209 
210 	int			(*classify)(struct sk_buff *,
211 					    const struct tcf_proto *,
212 					    struct tcf_result *);
213 	int			(*init)(struct tcf_proto*);
214 	void			(*destroy)(struct tcf_proto*);
215 
216 	unsigned long		(*get)(struct tcf_proto*, u32 handle);
217 	int			(*change)(struct net *net, struct sk_buff *,
218 					struct tcf_proto*, unsigned long,
219 					u32 handle, struct nlattr **,
220 					unsigned long *, bool);
221 	int			(*delete)(struct tcf_proto*, unsigned long, bool*);
222 	void			(*walk)(struct tcf_proto*, struct tcf_walker *arg);
223 
224 	/* rtnetlink specific */
225 	int			(*dump)(struct net*, struct tcf_proto*, unsigned long,
226 					struct sk_buff *skb, struct tcmsg*);
227 
228 	struct module		*owner;
229 };
230 
231 struct tcf_proto {
232 	/* Fast access part */
233 	struct tcf_proto __rcu	*next;
234 	void __rcu		*root;
235 	int			(*classify)(struct sk_buff *,
236 					    const struct tcf_proto *,
237 					    struct tcf_result *);
238 	__be16			protocol;
239 
240 	/* All the rest */
241 	u32			prio;
242 	u32			classid;
243 	struct Qdisc		*q;
244 	void			*data;
245 	const struct tcf_proto_ops	*ops;
246 	struct tcf_chain	*chain;
247 	struct rcu_head		rcu;
248 };
249 
250 struct qdisc_skb_cb {
251 	unsigned int		pkt_len;
252 	u16			slave_dev_queue_mapping;
253 	u16			tc_classid;
254 #define QDISC_CB_PRIV_LEN 20
255 	unsigned char		data[QDISC_CB_PRIV_LEN];
256 };
257 
258 struct tcf_chain {
259 	struct tcf_proto __rcu *filter_chain;
260 	struct tcf_proto __rcu **p_filter_chain;
261 	struct list_head list;
262 	struct tcf_block *block;
263 	u32 index; /* chain index */
264 	unsigned int refcnt;
265 };
266 
267 struct tcf_block {
268 	struct list_head chain_list;
269 };
270 
271 static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz)
272 {
273 	struct qdisc_skb_cb *qcb;
274 
275 	BUILD_BUG_ON(sizeof(skb->cb) < offsetof(struct qdisc_skb_cb, data) + sz);
276 	BUILD_BUG_ON(sizeof(qcb->data) < sz);
277 }
278 
279 static inline int qdisc_qlen(const struct Qdisc *q)
280 {
281 	return q->q.qlen;
282 }
283 
284 static inline struct qdisc_skb_cb *qdisc_skb_cb(const struct sk_buff *skb)
285 {
286 	return (struct qdisc_skb_cb *)skb->cb;
287 }
288 
289 static inline spinlock_t *qdisc_lock(struct Qdisc *qdisc)
290 {
291 	return &qdisc->q.lock;
292 }
293 
294 static inline struct Qdisc *qdisc_root(const struct Qdisc *qdisc)
295 {
296 	struct Qdisc *q = rcu_dereference_rtnl(qdisc->dev_queue->qdisc);
297 
298 	return q;
299 }
300 
301 static inline struct Qdisc *qdisc_root_sleeping(const struct Qdisc *qdisc)
302 {
303 	return qdisc->dev_queue->qdisc_sleeping;
304 }
305 
306 /* The qdisc root lock is a mechanism by which to top level
307  * of a qdisc tree can be locked from any qdisc node in the
308  * forest.  This allows changing the configuration of some
309  * aspect of the qdisc tree while blocking out asynchronous
310  * qdisc access in the packet processing paths.
311  *
312  * It is only legal to do this when the root will not change
313  * on us.  Otherwise we'll potentially lock the wrong qdisc
314  * root.  This is enforced by holding the RTNL semaphore, which
315  * all users of this lock accessor must do.
316  */
317 static inline spinlock_t *qdisc_root_lock(const struct Qdisc *qdisc)
318 {
319 	struct Qdisc *root = qdisc_root(qdisc);
320 
321 	ASSERT_RTNL();
322 	return qdisc_lock(root);
323 }
324 
325 static inline spinlock_t *qdisc_root_sleeping_lock(const struct Qdisc *qdisc)
326 {
327 	struct Qdisc *root = qdisc_root_sleeping(qdisc);
328 
329 	ASSERT_RTNL();
330 	return qdisc_lock(root);
331 }
332 
333 static inline seqcount_t *qdisc_root_sleeping_running(const struct Qdisc *qdisc)
334 {
335 	struct Qdisc *root = qdisc_root_sleeping(qdisc);
336 
337 	ASSERT_RTNL();
338 	return &root->running;
339 }
340 
341 static inline struct net_device *qdisc_dev(const struct Qdisc *qdisc)
342 {
343 	return qdisc->dev_queue->dev;
344 }
345 
346 static inline void sch_tree_lock(const struct Qdisc *q)
347 {
348 	spin_lock_bh(qdisc_root_sleeping_lock(q));
349 }
350 
351 static inline void sch_tree_unlock(const struct Qdisc *q)
352 {
353 	spin_unlock_bh(qdisc_root_sleeping_lock(q));
354 }
355 
356 #define tcf_tree_lock(tp)	sch_tree_lock((tp)->q)
357 #define tcf_tree_unlock(tp)	sch_tree_unlock((tp)->q)
358 
359 extern struct Qdisc noop_qdisc;
360 extern struct Qdisc_ops noop_qdisc_ops;
361 extern struct Qdisc_ops pfifo_fast_ops;
362 extern struct Qdisc_ops mq_qdisc_ops;
363 extern struct Qdisc_ops noqueue_qdisc_ops;
364 extern const struct Qdisc_ops *default_qdisc_ops;
365 static inline const struct Qdisc_ops *
366 get_default_qdisc_ops(const struct net_device *dev, int ntx)
367 {
368 	return ntx < dev->real_num_tx_queues ?
369 			default_qdisc_ops : &pfifo_fast_ops;
370 }
371 
372 struct Qdisc_class_common {
373 	u32			classid;
374 	struct hlist_node	hnode;
375 };
376 
377 struct Qdisc_class_hash {
378 	struct hlist_head	*hash;
379 	unsigned int		hashsize;
380 	unsigned int		hashmask;
381 	unsigned int		hashelems;
382 };
383 
384 static inline unsigned int qdisc_class_hash(u32 id, u32 mask)
385 {
386 	id ^= id >> 8;
387 	id ^= id >> 4;
388 	return id & mask;
389 }
390 
391 static inline struct Qdisc_class_common *
392 qdisc_class_find(const struct Qdisc_class_hash *hash, u32 id)
393 {
394 	struct Qdisc_class_common *cl;
395 	unsigned int h;
396 
397 	h = qdisc_class_hash(id, hash->hashmask);
398 	hlist_for_each_entry(cl, &hash->hash[h], hnode) {
399 		if (cl->classid == id)
400 			return cl;
401 	}
402 	return NULL;
403 }
404 
405 int qdisc_class_hash_init(struct Qdisc_class_hash *);
406 void qdisc_class_hash_insert(struct Qdisc_class_hash *,
407 			     struct Qdisc_class_common *);
408 void qdisc_class_hash_remove(struct Qdisc_class_hash *,
409 			     struct Qdisc_class_common *);
410 void qdisc_class_hash_grow(struct Qdisc *, struct Qdisc_class_hash *);
411 void qdisc_class_hash_destroy(struct Qdisc_class_hash *);
412 
413 void dev_init_scheduler(struct net_device *dev);
414 void dev_shutdown(struct net_device *dev);
415 void dev_activate(struct net_device *dev);
416 void dev_deactivate(struct net_device *dev);
417 void dev_deactivate_many(struct list_head *head);
418 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
419 			      struct Qdisc *qdisc);
420 void qdisc_reset(struct Qdisc *qdisc);
421 void qdisc_destroy(struct Qdisc *qdisc);
422 void qdisc_tree_reduce_backlog(struct Qdisc *qdisc, unsigned int n,
423 			       unsigned int len);
424 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
425 			  const struct Qdisc_ops *ops);
426 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
427 				const struct Qdisc_ops *ops, u32 parentid);
428 void __qdisc_calculate_pkt_len(struct sk_buff *skb,
429 			       const struct qdisc_size_table *stab);
430 int skb_do_redirect(struct sk_buff *);
431 
432 static inline void skb_reset_tc(struct sk_buff *skb)
433 {
434 #ifdef CONFIG_NET_CLS_ACT
435 	skb->tc_redirected = 0;
436 #endif
437 }
438 
439 static inline bool skb_at_tc_ingress(const struct sk_buff *skb)
440 {
441 #ifdef CONFIG_NET_CLS_ACT
442 	return skb->tc_at_ingress;
443 #else
444 	return false;
445 #endif
446 }
447 
448 static inline bool skb_skip_tc_classify(struct sk_buff *skb)
449 {
450 #ifdef CONFIG_NET_CLS_ACT
451 	if (skb->tc_skip_classify) {
452 		skb->tc_skip_classify = 0;
453 		return true;
454 	}
455 #endif
456 	return false;
457 }
458 
459 /* Reset all TX qdiscs greater then index of a device.  */
460 static inline void qdisc_reset_all_tx_gt(struct net_device *dev, unsigned int i)
461 {
462 	struct Qdisc *qdisc;
463 
464 	for (; i < dev->num_tx_queues; i++) {
465 		qdisc = rtnl_dereference(netdev_get_tx_queue(dev, i)->qdisc);
466 		if (qdisc) {
467 			spin_lock_bh(qdisc_lock(qdisc));
468 			qdisc_reset(qdisc);
469 			spin_unlock_bh(qdisc_lock(qdisc));
470 		}
471 	}
472 }
473 
474 static inline void qdisc_reset_all_tx(struct net_device *dev)
475 {
476 	qdisc_reset_all_tx_gt(dev, 0);
477 }
478 
479 /* Are all TX queues of the device empty?  */
480 static inline bool qdisc_all_tx_empty(const struct net_device *dev)
481 {
482 	unsigned int i;
483 
484 	rcu_read_lock();
485 	for (i = 0; i < dev->num_tx_queues; i++) {
486 		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
487 		const struct Qdisc *q = rcu_dereference(txq->qdisc);
488 
489 		if (q->q.qlen) {
490 			rcu_read_unlock();
491 			return false;
492 		}
493 	}
494 	rcu_read_unlock();
495 	return true;
496 }
497 
498 /* Are any of the TX qdiscs changing?  */
499 static inline bool qdisc_tx_changing(const struct net_device *dev)
500 {
501 	unsigned int i;
502 
503 	for (i = 0; i < dev->num_tx_queues; i++) {
504 		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
505 		if (rcu_access_pointer(txq->qdisc) != txq->qdisc_sleeping)
506 			return true;
507 	}
508 	return false;
509 }
510 
511 /* Is the device using the noop qdisc on all queues?  */
512 static inline bool qdisc_tx_is_noop(const struct net_device *dev)
513 {
514 	unsigned int i;
515 
516 	for (i = 0; i < dev->num_tx_queues; i++) {
517 		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
518 		if (rcu_access_pointer(txq->qdisc) != &noop_qdisc)
519 			return false;
520 	}
521 	return true;
522 }
523 
524 static inline unsigned int qdisc_pkt_len(const struct sk_buff *skb)
525 {
526 	return qdisc_skb_cb(skb)->pkt_len;
527 }
528 
529 /* additional qdisc xmit flags (NET_XMIT_MASK in linux/netdevice.h) */
530 enum net_xmit_qdisc_t {
531 	__NET_XMIT_STOLEN = 0x00010000,
532 	__NET_XMIT_BYPASS = 0x00020000,
533 };
534 
535 #ifdef CONFIG_NET_CLS_ACT
536 #define net_xmit_drop_count(e)	((e) & __NET_XMIT_STOLEN ? 0 : 1)
537 #else
538 #define net_xmit_drop_count(e)	(1)
539 #endif
540 
541 static inline void qdisc_calculate_pkt_len(struct sk_buff *skb,
542 					   const struct Qdisc *sch)
543 {
544 #ifdef CONFIG_NET_SCHED
545 	struct qdisc_size_table *stab = rcu_dereference_bh(sch->stab);
546 
547 	if (stab)
548 		__qdisc_calculate_pkt_len(skb, stab);
549 #endif
550 }
551 
552 static inline int qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch,
553 				struct sk_buff **to_free)
554 {
555 	qdisc_calculate_pkt_len(skb, sch);
556 	return sch->enqueue(skb, sch, to_free);
557 }
558 
559 static inline bool qdisc_is_percpu_stats(const struct Qdisc *q)
560 {
561 	return q->flags & TCQ_F_CPUSTATS;
562 }
563 
564 static inline void _bstats_update(struct gnet_stats_basic_packed *bstats,
565 				  __u64 bytes, __u32 packets)
566 {
567 	bstats->bytes += bytes;
568 	bstats->packets += packets;
569 }
570 
571 static inline void bstats_update(struct gnet_stats_basic_packed *bstats,
572 				 const struct sk_buff *skb)
573 {
574 	_bstats_update(bstats,
575 		       qdisc_pkt_len(skb),
576 		       skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1);
577 }
578 
579 static inline void _bstats_cpu_update(struct gnet_stats_basic_cpu *bstats,
580 				      __u64 bytes, __u32 packets)
581 {
582 	u64_stats_update_begin(&bstats->syncp);
583 	_bstats_update(&bstats->bstats, bytes, packets);
584 	u64_stats_update_end(&bstats->syncp);
585 }
586 
587 static inline void bstats_cpu_update(struct gnet_stats_basic_cpu *bstats,
588 				     const struct sk_buff *skb)
589 {
590 	u64_stats_update_begin(&bstats->syncp);
591 	bstats_update(&bstats->bstats, skb);
592 	u64_stats_update_end(&bstats->syncp);
593 }
594 
595 static inline void qdisc_bstats_cpu_update(struct Qdisc *sch,
596 					   const struct sk_buff *skb)
597 {
598 	bstats_cpu_update(this_cpu_ptr(sch->cpu_bstats), skb);
599 }
600 
601 static inline void qdisc_bstats_update(struct Qdisc *sch,
602 				       const struct sk_buff *skb)
603 {
604 	bstats_update(&sch->bstats, skb);
605 }
606 
607 static inline void qdisc_qstats_backlog_dec(struct Qdisc *sch,
608 					    const struct sk_buff *skb)
609 {
610 	sch->qstats.backlog -= qdisc_pkt_len(skb);
611 }
612 
613 static inline void qdisc_qstats_backlog_inc(struct Qdisc *sch,
614 					    const struct sk_buff *skb)
615 {
616 	sch->qstats.backlog += qdisc_pkt_len(skb);
617 }
618 
619 static inline void __qdisc_qstats_drop(struct Qdisc *sch, int count)
620 {
621 	sch->qstats.drops += count;
622 }
623 
624 static inline void qstats_drop_inc(struct gnet_stats_queue *qstats)
625 {
626 	qstats->drops++;
627 }
628 
629 static inline void qstats_overlimit_inc(struct gnet_stats_queue *qstats)
630 {
631 	qstats->overlimits++;
632 }
633 
634 static inline void qdisc_qstats_drop(struct Qdisc *sch)
635 {
636 	qstats_drop_inc(&sch->qstats);
637 }
638 
639 static inline void qdisc_qstats_cpu_drop(struct Qdisc *sch)
640 {
641 	this_cpu_inc(sch->cpu_qstats->drops);
642 }
643 
644 static inline void qdisc_qstats_overlimit(struct Qdisc *sch)
645 {
646 	sch->qstats.overlimits++;
647 }
648 
649 static inline void qdisc_skb_head_init(struct qdisc_skb_head *qh)
650 {
651 	qh->head = NULL;
652 	qh->tail = NULL;
653 	qh->qlen = 0;
654 }
655 
656 static inline int __qdisc_enqueue_tail(struct sk_buff *skb, struct Qdisc *sch,
657 				       struct qdisc_skb_head *qh)
658 {
659 	struct sk_buff *last = qh->tail;
660 
661 	if (last) {
662 		skb->next = NULL;
663 		last->next = skb;
664 		qh->tail = skb;
665 	} else {
666 		qh->tail = skb;
667 		qh->head = skb;
668 	}
669 	qh->qlen++;
670 	qdisc_qstats_backlog_inc(sch, skb);
671 
672 	return NET_XMIT_SUCCESS;
673 }
674 
675 static inline int qdisc_enqueue_tail(struct sk_buff *skb, struct Qdisc *sch)
676 {
677 	return __qdisc_enqueue_tail(skb, sch, &sch->q);
678 }
679 
680 static inline struct sk_buff *__qdisc_dequeue_head(struct qdisc_skb_head *qh)
681 {
682 	struct sk_buff *skb = qh->head;
683 
684 	if (likely(skb != NULL)) {
685 		qh->head = skb->next;
686 		qh->qlen--;
687 		if (qh->head == NULL)
688 			qh->tail = NULL;
689 		skb->next = NULL;
690 	}
691 
692 	return skb;
693 }
694 
695 static inline struct sk_buff *qdisc_dequeue_head(struct Qdisc *sch)
696 {
697 	struct sk_buff *skb = __qdisc_dequeue_head(&sch->q);
698 
699 	if (likely(skb != NULL)) {
700 		qdisc_qstats_backlog_dec(sch, skb);
701 		qdisc_bstats_update(sch, skb);
702 	}
703 
704 	return skb;
705 }
706 
707 /* Instead of calling kfree_skb() while root qdisc lock is held,
708  * queue the skb for future freeing at end of __dev_xmit_skb()
709  */
710 static inline void __qdisc_drop(struct sk_buff *skb, struct sk_buff **to_free)
711 {
712 	skb->next = *to_free;
713 	*to_free = skb;
714 }
715 
716 static inline unsigned int __qdisc_queue_drop_head(struct Qdisc *sch,
717 						   struct qdisc_skb_head *qh,
718 						   struct sk_buff **to_free)
719 {
720 	struct sk_buff *skb = __qdisc_dequeue_head(qh);
721 
722 	if (likely(skb != NULL)) {
723 		unsigned int len = qdisc_pkt_len(skb);
724 
725 		qdisc_qstats_backlog_dec(sch, skb);
726 		__qdisc_drop(skb, to_free);
727 		return len;
728 	}
729 
730 	return 0;
731 }
732 
733 static inline unsigned int qdisc_queue_drop_head(struct Qdisc *sch,
734 						 struct sk_buff **to_free)
735 {
736 	return __qdisc_queue_drop_head(sch, &sch->q, to_free);
737 }
738 
739 static inline struct sk_buff *qdisc_peek_head(struct Qdisc *sch)
740 {
741 	const struct qdisc_skb_head *qh = &sch->q;
742 
743 	return qh->head;
744 }
745 
746 /* generic pseudo peek method for non-work-conserving qdisc */
747 static inline struct sk_buff *qdisc_peek_dequeued(struct Qdisc *sch)
748 {
749 	/* we can reuse ->gso_skb because peek isn't called for root qdiscs */
750 	if (!sch->gso_skb) {
751 		sch->gso_skb = sch->dequeue(sch);
752 		if (sch->gso_skb) {
753 			/* it's still part of the queue */
754 			qdisc_qstats_backlog_inc(sch, sch->gso_skb);
755 			sch->q.qlen++;
756 		}
757 	}
758 
759 	return sch->gso_skb;
760 }
761 
762 /* use instead of qdisc->dequeue() for all qdiscs queried with ->peek() */
763 static inline struct sk_buff *qdisc_dequeue_peeked(struct Qdisc *sch)
764 {
765 	struct sk_buff *skb = sch->gso_skb;
766 
767 	if (skb) {
768 		sch->gso_skb = NULL;
769 		qdisc_qstats_backlog_dec(sch, skb);
770 		sch->q.qlen--;
771 	} else {
772 		skb = sch->dequeue(sch);
773 	}
774 
775 	return skb;
776 }
777 
778 static inline void __qdisc_reset_queue(struct qdisc_skb_head *qh)
779 {
780 	/*
781 	 * We do not know the backlog in bytes of this list, it
782 	 * is up to the caller to correct it
783 	 */
784 	ASSERT_RTNL();
785 	if (qh->qlen) {
786 		rtnl_kfree_skbs(qh->head, qh->tail);
787 
788 		qh->head = NULL;
789 		qh->tail = NULL;
790 		qh->qlen = 0;
791 	}
792 }
793 
794 static inline void qdisc_reset_queue(struct Qdisc *sch)
795 {
796 	__qdisc_reset_queue(&sch->q);
797 	sch->qstats.backlog = 0;
798 }
799 
800 static inline struct Qdisc *qdisc_replace(struct Qdisc *sch, struct Qdisc *new,
801 					  struct Qdisc **pold)
802 {
803 	struct Qdisc *old;
804 
805 	sch_tree_lock(sch);
806 	old = *pold;
807 	*pold = new;
808 	if (old != NULL) {
809 		qdisc_tree_reduce_backlog(old, old->q.qlen, old->qstats.backlog);
810 		qdisc_reset(old);
811 	}
812 	sch_tree_unlock(sch);
813 
814 	return old;
815 }
816 
817 static inline void rtnl_qdisc_drop(struct sk_buff *skb, struct Qdisc *sch)
818 {
819 	rtnl_kfree_skbs(skb, skb);
820 	qdisc_qstats_drop(sch);
821 }
822 
823 
824 static inline int qdisc_drop(struct sk_buff *skb, struct Qdisc *sch,
825 			     struct sk_buff **to_free)
826 {
827 	__qdisc_drop(skb, to_free);
828 	qdisc_qstats_drop(sch);
829 
830 	return NET_XMIT_DROP;
831 }
832 
833 /* Length to Time (L2T) lookup in a qdisc_rate_table, to determine how
834    long it will take to send a packet given its size.
835  */
836 static inline u32 qdisc_l2t(struct qdisc_rate_table* rtab, unsigned int pktlen)
837 {
838 	int slot = pktlen + rtab->rate.cell_align + rtab->rate.overhead;
839 	if (slot < 0)
840 		slot = 0;
841 	slot >>= rtab->rate.cell_log;
842 	if (slot > 255)
843 		return rtab->data[255]*(slot >> 8) + rtab->data[slot & 0xFF];
844 	return rtab->data[slot];
845 }
846 
847 struct psched_ratecfg {
848 	u64	rate_bytes_ps; /* bytes per second */
849 	u32	mult;
850 	u16	overhead;
851 	u8	linklayer;
852 	u8	shift;
853 };
854 
855 static inline u64 psched_l2t_ns(const struct psched_ratecfg *r,
856 				unsigned int len)
857 {
858 	len += r->overhead;
859 
860 	if (unlikely(r->linklayer == TC_LINKLAYER_ATM))
861 		return ((u64)(DIV_ROUND_UP(len,48)*53) * r->mult) >> r->shift;
862 
863 	return ((u64)len * r->mult) >> r->shift;
864 }
865 
866 void psched_ratecfg_precompute(struct psched_ratecfg *r,
867 			       const struct tc_ratespec *conf,
868 			       u64 rate64);
869 
870 static inline void psched_ratecfg_getrate(struct tc_ratespec *res,
871 					  const struct psched_ratecfg *r)
872 {
873 	memset(res, 0, sizeof(*res));
874 
875 	/* legacy struct tc_ratespec has a 32bit @rate field
876 	 * Qdisc using 64bit rate should add new attributes
877 	 * in order to maintain compatibility.
878 	 */
879 	res->rate = min_t(u64, r->rate_bytes_ps, ~0U);
880 
881 	res->overhead = r->overhead;
882 	res->linklayer = (r->linklayer & TC_LINKLAYER_MASK);
883 }
884 
885 #endif
886