summaryrefslogtreecommitdiffstats
path: root/net/sched/sch_sfb.c
blob: d7eea99333e96a33a953106a3a0f2fdb32a12385 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
/*
 * net/sched/sch_sfb.c	  Stochastic Fair Blue
 *
 * Copyright (c) 2008-2011 Juliusz Chroboczek <jch@pps.jussieu.fr>
 * Copyright (c) 2011 Eric Dumazet <eric.dumazet@gmail.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * W. Feng, D. Kandlur, D. Saha, K. Shin. Blue:
 * A New Class of Active Queue Management Algorithms.
 * U. Michigan CSE-TR-387-99, April 1999.
 *
 * http://www.thefengs.com/wuchang/blue/CSE-TR-387-99.pdf
 *
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/random.h>
#include <linux/jhash.h>
#include <net/ip.h>
#include <net/pkt_sched.h>
#include <net/inet_ecn.h>
#include <net/flow_keys.h>

/*
 * SFB uses two B[l][n] : L x N arrays of bins (L levels, N bins per level)
 * This implementation uses L = 8 and N = 16
 * This permits us to split one 32bit hash (provided per packet by rxhash or
 * external classifier) into 8 subhashes of 4 bits.
 */
#define SFB_BUCKET_SHIFT 4
#define SFB_NUMBUCKETS	(1 << SFB_BUCKET_SHIFT) /* N bins per Level */
#define SFB_BUCKET_MASK (SFB_NUMBUCKETS - 1)
#define SFB_LEVELS	(32 / SFB_BUCKET_SHIFT) /* L */

/* SFB algo uses a virtual queue, named "bin" */
struct sfb_bucket {
	u16		qlen; /* length of virtual queue */
	u16		p_mark; /* marking probability */
};

/* We use a double buffering right before hash change
 * (Section 4.4 of SFB reference : moving hash functions)
 */
struct sfb_bins {
	u32		  perturbation; /* jhash perturbation */
	struct sfb_bucket bins[SFB_LEVELS][SFB_NUMBUCKETS];
};

struct sfb_sched_data {
	struct Qdisc	*qdisc;
	struct tcf_proto *filter_list;
	unsigned long	rehash_interval;
	unsigned long	warmup_time;	/* double buffering warmup time in jiffies */
	u32		max;
	u32		bin_size;	/* maximum queue length per bin */
	u32		increment;	/* d1 */
	u32		decrement;	/* d2 */
	u32		limit;		/* HARD maximal queue length */
	u32		penalty_rate;
	u32		penalty_burst;
	u32		tokens_avail;
	unsigned long	rehash_time;
	unsigned long	token_time;

	u8		slot;		/* current active bins (0 or 1) */
	bool		double_buffering;
	struct sfb_bins bins[2];

	struct {
		u32	earlydrop;
		u32	penaltydrop;
		u32	bucketdrop;
		u32	queuedrop;
		u32	childdrop;	/* drops in child qdisc */
		u32	marked;		/* ECN mark */
	} stats;
};

/*
 * Each queued skb might be hashed on one or two bins
 * We store in skb_cb the two hash values.
 * (A zero value means double buffering was not used)
 */
struct sfb_skb_cb {
	u32 hashes[2];
};

static inline struct sfb_skb_cb *sfb_skb_cb(const struct sk_buff *skb)
{
	qdisc_cb_private_validate(skb, sizeof(struct sfb_skb_cb));
	return (struct sfb_skb_cb *)qdisc_skb_cb(skb)->data;
}

/*
 * If using 'internal' SFB flow classifier, hash comes from skb rxhash
 * If using external classifier, hash comes from the classid.
 */
static u32 sfb_hash(const struct sk_buff *skb, u32 slot)
{
	return sfb_skb_cb(skb)->hashes[slot];
}

/* Probabilities are coded as Q0.16 fixed-point values,
 * with 0xFFFF representing 65535/65536 (almost 1.0)
 * Addition and subtraction are saturating in [0, 65535]
 */
static u32 prob_plus(u32 p1, u32 p2)
{
	u32 res = p1 + p2;

	return min_t(u32, res, SFB_MAX_PROB);
}

static u32 prob_minus(u32 p1, u32 p2)
{
	return p1 > p2 ? p1 - p2 : 0;
}

static void increment_one_qlen(u32 sfbhash, u32 slot, struct sfb_sched_data *q)
{
	int i;
	struct sfb_bucket *b = &q->bins[slot].bins[0][0];

	for (i = 0; i < SFB_LEVELS; i++) {
		u32 hash = sfbhash & SFB_BUCKET_MASK;

		sfbhash >>= SFB_BUCKET_SHIFT;
		if (b[hash].qlen < 0xFFFF)
			b[hash].qlen++;
		b += SFB_NUMBUCKETS; /* next level */
	}
}

static void increment_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
{
	u32 sfbhash;

	sfbhash = sfb_hash(skb, 0);
	if (sfbhash)
		increment_one_qlen(sfbhash, 0, q);

	sfbhash = sfb_hash(skb, 1);
	if (sfbhash)
		increment_one_qlen(sfbhash, 1, q);
}

static void decrement_one_qlen(u32 sfbhash, u32 slot,
			       struct sfb_sched_data *q)
{
	int i;
	struct sfb_bucket *b = &q->bins[slot].bins[0][0];

	for (i = 0; i < SFB_LEVELS; i++) {
		u32 hash = sfbhash & SFB_BUCKET_MASK;

		sfbhash >>= SFB_BUCKET_SHIFT;
		if (b[hash].qlen > 0)
			b[hash].qlen--;
		b += SFB_NUMBUCKETS; /* next level */
	}
}

static void decrement_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
{
	u32 sfbhash;

	sfbhash = sfb_hash(skb, 0);
	if (sfbhash)
		decrement_one_qlen(sfbhash, 0, q);

	sfbhash = sfb_hash(skb, 1);
	if (sfbhash)
		decrement_one_qlen(sfbhash, 1, q);
}

static void decrement_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
{
	b->p_mark = prob_minus(b->p_mark, q->decrement);
}

static void increment_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
{
	b->p_mark = prob_plus(b->p_mark, q->increment);
}

static void sfb_zero_all_buckets(struct sfb_sched_data *q)
{
	memset(&q->bins, 0, sizeof(q->bins));
}

/*
 * compute max qlen, max p_mark, and avg p_mark
 */
static u32 sfb_compute_qlen(u32 *prob_r, u32 *avgpm_r, const struct sfb_sched_data *q)
{
	int i;
	u32 qlen = 0, prob = 0, totalpm = 0;
	const struct sfb_bucket *b = &q->bins[q->slot].bins[0][0];

	for (i = 0; i < SFB_LEVELS * SFB_NUMBUCKETS; i++) {
		if (qlen < b->qlen)
			qlen = b->qlen;
		totalpm += b->p_mark;
		if (prob < b->p_mark)
			prob = b->p_mark;
		b++;
	}
	*prob_r = prob;
	*avgpm_r = totalpm / (SFB_LEVELS * SFB_NUMBUCKETS);
	return qlen;
}


static void sfb_init_perturbation(u32 slot, struct sfb_sched_data *q)
{
	q->bins[slot].perturbation = net_random();
}

static void sfb_swap_slot(struct sfb_sched_data *q)
{
	sfb_init_perturbation(q->slot, q);
	q->slot ^= 1;
	q->double_buffering = false;
}

/* Non elastic flows are allowed to use part of the bandwidth, expressed
 * in "penalty_rate" packets per second, with "penalty_burst" burst
 */
static bool sfb_rate_limit(struct sk_buff *skb, struct sfb_sched_data *q)
{
	if (q->penalty_rate == 0 || q->penalty_burst == 0)
		return true;

	if (q->tokens_avail < 1) {
		unsigned long age = min(10UL * HZ, jiffies - q->token_time);

		q->tokens_avail = (age * q->penalty_rate) / HZ;
		if (q->tokens_avail > q->penalty_burst)
			q->tokens_avail = q->penalty_burst;
		q->token_time = jiffies;
		if (q->tokens_avail < 1)
			return true;
	}

	q->tokens_avail--;
	return false;
}

static bool sfb_classify(struct sk_buff *skb, struct sfb_sched_data *q,
			 int *qerr, u32 *salt)
{
	struct tcf_result res;
	int result;

	result = tc_classify(skb, q->filter_list, &res);
	if (result >= 0) {
#ifdef CONFIG_NET_CLS_ACT
		switch (result) {
		case TC_ACT_STOLEN:
		case TC_ACT_QUEUED:
			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
		case TC_ACT_SHOT:
			return false;
		}
#endif
		*salt = TC_H_MIN(res.classid);
		return true;
	}
	return false;
}

static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{

	struct sfb_sched_data *q = qdisc_priv(sch);
	struct Qdisc *child = q->qdisc;
	int i;
	u32 p_min = ~0;
	u32 minqlen = ~0;
	u32 r, slot, salt, sfbhash;
	int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
	struct flow_keys keys;

	if (unlikely(sch->q.qlen >= q->limit)) {
		sch->qstats.overlimits++;
		q->stats.queuedrop++;
		goto drop;
	}

	if (q->rehash_interval > 0) {
		unsigned long limit = q->rehash_time + q->rehash_interval;

		if (unlikely(time_after(jiffies, limit))) {
			sfb_swap_slot(q);
			q->rehash_time = jiffies;
		} else if (unlikely(!q->double_buffering && q->warmup_time > 0 &&
				    time_after(jiffies, limit - q->warmup_time))) {
			q->double_buffering = true;
		}
	}

	if (q->filter_list) {
		/* If using external classifiers, get result and record it. */
		if (!sfb_classify(skb, q, &ret, &salt))
			goto other_drop;
		keys.src = salt;
		keys.dst = 0;
		keys.ports = 0;
	} else {
		skb_flow_dissect(skb, &keys);
	}

	slot = q->slot;

	sfbhash = jhash_3words((__force u32)keys.dst,
			       (__force u32)keys.src,
			       (__force u32)keys.ports,
			       q->bins[slot].perturbation);
	if (!sfbhash)
		sfbhash = 1;
	sfb_skb_cb(skb)->hashes[slot] = sfbhash;

	for (i = 0; i < SFB_LEVELS; i++) {
		u32 hash = sfbhash & SFB_BUCKET_MASK;
		struct sfb_bucket *b = &q->bins[slot].bins[i][hash];

		sfbhash >>= SFB_BUCKET_SHIFT;
		if (b->qlen == 0)
			decrement_prob(b, q);
		else if (b->qlen >= q->bin_size)
			increment_prob(b, q);
		if (minqlen > b->qlen)
			minqlen = b->qlen;
		if (p_min > b->p_mark)
			p_min = b->p_mark;
	}

	slot ^= 1;
	sfb_skb_cb(skb)->hashes[slot] = 0;

	if (unlikely(minqlen >= q->max)) {
		sch->qstats.overlimits++;
		q->stats.bucketdrop++;
		goto drop;
	}

	if (unlikely(p_min >= SFB_MAX_PROB)) {
		/* Inelastic flow */
		if (q->double_buffering) {
			sfbhash = jhash_3words((__force u32)keys.dst,
					       (__force u32)keys.src,
					       (__force u32)keys.ports,
					       q->bins[slot].perturbation);
			if (!sfbhash)
				sfbhash = 1;
			sfb_skb_cb(skb)->hashes[slot] = sfbhash;

			for (i = 0; i < SFB_LEVELS; i++) {
				u32 hash = sfbhash & SFB_BUCKET_MASK;
				struct sfb_bucket *b = &q->bins[slot].bins[i][hash];

				sfbhash >>= SFB_BUCKET_SHIFT;
				if (b->qlen == 0)
					decrement_prob(b, q);
				else if (b->qlen >= q->bin_size)
					increment_prob(b, q);
			}
		}
		if (sfb_rate_limit(skb, q)) {
			sch->qstats.overlimits++;
			q->stats.penaltydrop++;
			goto drop;
		}
		goto enqueue;
	}

	r = net_random() & SFB_MAX_PROB;

	if (unlikely(r < p_min)) {
		if (unlikely(p_min > SFB_MAX_PROB / 2)) {
			/* If we're marking that many packets, then either
			 * this flow is unresponsive, or we're badly congested.
			 * In either case, we want to start dropping packets.
			 */
			if (r < (p_min - SFB_MAX_PROB / 2) * 2) {
				q->stats.earlydrop++;
				goto drop;
			}
		}
		if (INET_ECN_set_ce(skb)) {
			q->stats.marked++;
		} else {
			q->stats.earlydrop++;
			goto drop;
		}
	}

enqueue:
	ret = qdisc_enqueue(skb, child);
	if (likely(ret == NET_XMIT_SUCCESS)) {
		sch->q.qlen++;
		increment_qlen(skb, q);
	} else if (net_xmit_drop_count(ret)) {
		q->stats.childdrop++;
		sch->qstats.drops++;
	}
	return ret;

drop:
	qdisc_drop(skb, sch);
	return NET_XMIT_CN;
other_drop:
	if (ret & __NET_XMIT_BYPASS)
		sch->qstats.drops++;
	kfree_skb(skb);
	return ret;
}

static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
{
	struct sfb_sched_data *q = qdisc_priv(sch);
	struct Qdisc *child = q->qdisc;
	struct sk_buff *skb;

	skb = child->dequeue(q->qdisc);

	if (skb) {
		qdisc_bstats_update(sch, skb);
		sch->q.qlen--;
		decrement_qlen(skb, q);
	}

	return skb;
}

static struct sk_buff *sfb_peek(struct Qdisc *sch)
{
	struct sfb_sched_data *q = qdisc_priv(sch);
	struct Qdisc *child = q->qdisc;

	return child->ops->peek(child);
}

/* No sfb_drop -- impossible since the child doesn't return the dropped skb. */

static void sfb_reset(struct Qdisc *sch)
{
	struct sfb_sched_data *q = qdisc_priv(sch);

	qdisc_reset(q->qdisc);
	sch->q.qlen = 0;
	q->slot = 0;
	q->double_buffering = false;
	sfb_zero_all_buckets(q);
	sfb_init_perturbation(0, q);
}

static void sfb_destroy(struct Qdisc *sch)
{
	struct sfb_sched_data *q = qdisc_priv(sch);

	tcf_destroy_chain(&q->filter_list);
	qdisc_destroy(q->qdisc);
}

static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
	[TCA_SFB_PARMS]	= { .len = sizeof(struct tc_sfb_qopt) },
};

static const struct tc_sfb_qopt sfb_default_ops = {
	.rehash_interval = 600 * MSEC_PER_SEC,
	.warmup_time = 60 * MSEC_PER_SEC,
	.limit = 0,
	.max = 25,
	.bin_size = 20,
	.increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
	.decrement = (SFB_MAX_PROB + 3000) / 6000,
	.penalty_rate = 10,
	.penalty_burst = 20,
};

static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
{
	struct sfb_sched_data *q = qdisc_priv(sch);
	struct Qdisc *child;
	struct nlattr *tb[TCA_SFB_MAX + 1];
	const struct tc_sfb_qopt *ctl = &sfb_default_ops;
	u32 limit;
	int err;

	if (opt) {
		err = nla_parse_nested(tb, TCA_SFB_MAX, opt, sfb_policy);
		if (err < 0)
			return -EINVAL;

		if (tb[TCA_SFB_PARMS] == NULL)
			return -EINVAL;

		ctl = nla_data(tb[TCA_SFB_PARMS]);
	}

	limit = ctl->limit;
	if (limit == 0)
		limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);

	child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
	if (IS_ERR(child))
		return PTR_ERR(child);

	sch_tree_lock(sch);

	qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
	qdisc_destroy(q->qdisc);
	q->qdisc = child;

	q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
	q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
	q->rehash_time = jiffies;
	q->limit = limit;
	q->increment = ctl->increment;
	q->decrement = ctl->decrement;
	q->max = ctl->max;
	q->bin_size = ctl->bin_size;
	q->penalty_rate = ctl->penalty_rate;
	q->penalty_burst = ctl->penalty_burst;
	q->tokens_avail = ctl->penalty_burst;
	q->token_time = jiffies;

	q->slot = 0;
	q->double_buffering = false;
	sfb_zero_all_buckets(q);
	sfb_init_perturbation(0, q);
	sfb_init_perturbation(1, q);

	sch_tree_unlock(sch);

	return 0;
}

static int sfb_init(struct Qdisc *sch, struct nlattr *opt)
{
	struct sfb_sched_data *q = qdisc_priv(sch);

	q->qdisc = &noop_qdisc;
	return sfb_change(sch, opt);
}

static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
{
	struct sfb_sched_data *q = qdisc_priv(sch);
	struct nlattr *opts;
	struct tc_sfb_qopt opt = {
		.rehash_interval = jiffies_to_msecs(q->rehash_interval),
		.warmup_time = jiffies_to_msecs(q->warmup_time),
		.limit = q->limit,
		.max = q->max,
		.bin_size = q->bin_size,
		.increment = q->increment,
		.decrement = q->decrement,
		.penalty_rate = q->penalty_rate,
		.penalty_burst = q->penalty_burst,
	};

	sch->qstats.backlog = q->qdisc->qstats.backlog;
	opts = nla_nest_start(skb, TCA_OPTIONS);
	NLA_PUT(skb, TCA_SFB_PARMS, sizeof(opt), &opt);
	return nla_nest_end(skb, opts);

nla_put_failure:
	nla_nest_cancel(skb, opts);
	return -EMSGSIZE;
}

static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
{
	struct sfb_sched_data *q = qdisc_priv(sch);
	struct tc_sfb_xstats st = {
		.earlydrop = q->stats.earlydrop,
		.penaltydrop = q->stats.penaltydrop,
		.bucketdrop = q->stats.bucketdrop,
		.queuedrop = q->stats.queuedrop,
		.childdrop = q->stats.childdrop,
		.marked = q->stats.marked,
	};

	st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);

	return gnet_stats_copy_app(d, &st, sizeof(st));
}

static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
			  struct sk_buff *skb, struct tcmsg *tcm)
{
	return -ENOSYS;
}

static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
		     struct Qdisc **old)
{
	struct sfb_sched_data *q = qdisc_priv(sch);

	if (new == NULL)
		new = &noop_qdisc;

	sch_tree_lock(sch);
	*old = q->qdisc;
	q->qdisc = new;
	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
	qdisc_reset(*old);
	sch_tree_unlock(sch);
	return 0;
}

static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
{
	struct sfb_sched_data *q = qdisc_priv(sch);

	return q->qdisc;
}

static unsigned long sfb_get(struct Qdisc *sch, u32 classid)
{
	return 1;
}

static void sfb_put(struct Qdisc *sch, unsigned long arg)
{
}

static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
			    struct nlattr **tca, unsigned long *arg)
{
	return -ENOSYS;
}

static int sfb_delete(struct Qdisc *sch, unsigned long cl)
{
	return -ENOSYS;
}

static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
{
	if (!walker->stop) {
		if (walker->count >= walker->skip)
			if (walker->fn(sch, 1, walker) < 0) {
				walker->stop = 1;
				return;
			}
		walker->count++;
	}
}

static struct tcf_proto **sfb_find_tcf(struct Qdisc *sch, unsigned long cl)
{
	struct sfb_sched_data *q = qdisc_priv(sch);

	if (cl)
		return NULL;
	return &q->filter_list;
}

static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
			      u32 classid)
{
	return 0;
}


static const struct Qdisc_class_ops sfb_class_ops = {
	.graft		=	sfb_graft,
	.leaf		=	sfb_leaf,
	.get		=	sfb_get,
	.put		=	sfb_put,
	.change		=	sfb_change_class,
	.delete		=	sfb_delete,
	.walk		=	sfb_walk,
	.tcf_chain	=	sfb_find_tcf,
	.bind_tcf	=	sfb_bind,
	.unbind_tcf	=	sfb_put,
	.dump		=	sfb_dump_class,
};

static struct Qdisc_ops sfb_qdisc_ops __read_mostly = {
	.id		=	"sfb",
	.priv_size	=	sizeof(struct sfb_sched_data),
	.cl_ops		=	&sfb_class_ops,
	.enqueue	=	sfb_enqueue,
	.dequeue	=	sfb_dequeue,
	.peek		=	sfb_peek,
	.init		=	sfb_init,
	.reset		=	sfb_reset,
	.destroy	=	sfb_destroy,
	.change		=	sfb_change,
	.dump		=	sfb_dump,
	.dump_stats	=	sfb_dump_stats,
	.owner		=	THIS_MODULE,
};

static int __init sfb_module_init(void)
{
	return register_qdisc(&sfb_qdisc_ops);
}

static void __exit sfb_module_exit(void)
{
	unregister_qdisc(&sfb_qdisc_ops);
}

module_init(sfb_module_init)
module_exit(sfb_module_exit)

MODULE_DESCRIPTION("Stochastic Fair Blue queue discipline");
MODULE_AUTHOR("Juliusz Chroboczek");
MODULE_AUTHOR("Eric Dumazet");
MODULE_LICENSE("GPL");