1/*
2 * net/sched/sch_sfb.c	  Stochastic Fair Blue
3 *
4 * Copyright (c) 2008-2011 Juliusz Chroboczek <jch@pps.jussieu.fr>
5 * Copyright (c) 2011 Eric Dumazet <eric.dumazet@gmail.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * version 2 as published by the Free Software Foundation.
10 *
11 * W. Feng, D. Kandlur, D. Saha, K. Shin. Blue:
12 * A New Class of Active Queue Management Algorithms.
13 * U. Michigan CSE-TR-387-99, April 1999.
14 *
15 * http://www.thefengs.com/wuchang/blue/CSE-TR-387-99.pdf
16 *
17 */
18
19#include <linux/module.h>
20#include <linux/types.h>
21#include <linux/kernel.h>
22#include <linux/errno.h>
23#include <linux/skbuff.h>
24#include <linux/random.h>
25#include <linux/jhash.h>
26#include <net/ip.h>
27#include <net/pkt_sched.h>
28#include <net/inet_ecn.h>
29#include <net/flow_keys.h>
30
31/*
32 * SFB uses two B[l][n] : L x N arrays of bins (L levels, N bins per level)
33 * This implementation uses L = 8 and N = 16
34 * This permits us to split one 32bit hash (provided per packet by rxhash or
35 * external classifier) into 8 subhashes of 4 bits.
36 */
37#define SFB_BUCKET_SHIFT 4
38#define SFB_NUMBUCKETS	(1 << SFB_BUCKET_SHIFT) /* N bins per Level */
39#define SFB_BUCKET_MASK (SFB_NUMBUCKETS - 1)
40#define SFB_LEVELS	(32 / SFB_BUCKET_SHIFT) /* L */
41
42/* SFB algo uses a virtual queue, named "bin" */
43struct sfb_bucket {
44	u16		qlen; /* length of virtual queue */
45	u16		p_mark; /* marking probability */
46};
47
48/* We use a double buffering right before hash change
49 * (Section 4.4 of SFB reference : moving hash functions)
50 */
51struct sfb_bins {
52	u32		  perturbation; /* jhash perturbation */
53	struct sfb_bucket bins[SFB_LEVELS][SFB_NUMBUCKETS];
54};
55
56struct sfb_sched_data {
57	struct Qdisc	*qdisc;
58	struct tcf_proto __rcu *filter_list;
59	unsigned long	rehash_interval;
60	unsigned long	warmup_time;	/* double buffering warmup time in jiffies */
61	u32		max;
62	u32		bin_size;	/* maximum queue length per bin */
63	u32		increment;	/* d1 */
64	u32		decrement;	/* d2 */
65	u32		limit;		/* HARD maximal queue length */
66	u32		penalty_rate;
67	u32		penalty_burst;
68	u32		tokens_avail;
69	unsigned long	rehash_time;
70	unsigned long	token_time;
71
72	u8		slot;		/* current active bins (0 or 1) */
73	bool		double_buffering;
74	struct sfb_bins bins[2];
75
76	struct {
77		u32	earlydrop;
78		u32	penaltydrop;
79		u32	bucketdrop;
80		u32	queuedrop;
81		u32	childdrop;	/* drops in child qdisc */
82		u32	marked;		/* ECN mark */
83	} stats;
84};
85
86/*
87 * Each queued skb might be hashed on one or two bins
88 * We store in skb_cb the two hash values.
89 * (A zero value means double buffering was not used)
90 */
91struct sfb_skb_cb {
92	u32 hashes[2];
93};
94
95static inline struct sfb_skb_cb *sfb_skb_cb(const struct sk_buff *skb)
96{
97	qdisc_cb_private_validate(skb, sizeof(struct sfb_skb_cb));
98	return (struct sfb_skb_cb *)qdisc_skb_cb(skb)->data;
99}
100
101/*
102 * If using 'internal' SFB flow classifier, hash comes from skb rxhash
103 * If using external classifier, hash comes from the classid.
104 */
105static u32 sfb_hash(const struct sk_buff *skb, u32 slot)
106{
107	return sfb_skb_cb(skb)->hashes[slot];
108}
109
110/* Probabilities are coded as Q0.16 fixed-point values,
111 * with 0xFFFF representing 65535/65536 (almost 1.0)
112 * Addition and subtraction are saturating in [0, 65535]
113 */
114static u32 prob_plus(u32 p1, u32 p2)
115{
116	u32 res = p1 + p2;
117
118	return min_t(u32, res, SFB_MAX_PROB);
119}
120
121static u32 prob_minus(u32 p1, u32 p2)
122{
123	return p1 > p2 ? p1 - p2 : 0;
124}
125
126static void increment_one_qlen(u32 sfbhash, u32 slot, struct sfb_sched_data *q)
127{
128	int i;
129	struct sfb_bucket *b = &q->bins[slot].bins[0][0];
130
131	for (i = 0; i < SFB_LEVELS; i++) {
132		u32 hash = sfbhash & SFB_BUCKET_MASK;
133
134		sfbhash >>= SFB_BUCKET_SHIFT;
135		if (b[hash].qlen < 0xFFFF)
136			b[hash].qlen++;
137		b += SFB_NUMBUCKETS; /* next level */
138	}
139}
140
141static void increment_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
142{
143	u32 sfbhash;
144
145	sfbhash = sfb_hash(skb, 0);
146	if (sfbhash)
147		increment_one_qlen(sfbhash, 0, q);
148
149	sfbhash = sfb_hash(skb, 1);
150	if (sfbhash)
151		increment_one_qlen(sfbhash, 1, q);
152}
153
154static void decrement_one_qlen(u32 sfbhash, u32 slot,
155			       struct sfb_sched_data *q)
156{
157	int i;
158	struct sfb_bucket *b = &q->bins[slot].bins[0][0];
159
160	for (i = 0; i < SFB_LEVELS; i++) {
161		u32 hash = sfbhash & SFB_BUCKET_MASK;
162
163		sfbhash >>= SFB_BUCKET_SHIFT;
164		if (b[hash].qlen > 0)
165			b[hash].qlen--;
166		b += SFB_NUMBUCKETS; /* next level */
167	}
168}
169
170static void decrement_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
171{
172	u32 sfbhash;
173
174	sfbhash = sfb_hash(skb, 0);
175	if (sfbhash)
176		decrement_one_qlen(sfbhash, 0, q);
177
178	sfbhash = sfb_hash(skb, 1);
179	if (sfbhash)
180		decrement_one_qlen(sfbhash, 1, q);
181}
182
183static void decrement_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
184{
185	b->p_mark = prob_minus(b->p_mark, q->decrement);
186}
187
188static void increment_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
189{
190	b->p_mark = prob_plus(b->p_mark, q->increment);
191}
192
193static void sfb_zero_all_buckets(struct sfb_sched_data *q)
194{
195	memset(&q->bins, 0, sizeof(q->bins));
196}
197
198/*
199 * compute max qlen, max p_mark, and avg p_mark
200 */
201static u32 sfb_compute_qlen(u32 *prob_r, u32 *avgpm_r, const struct sfb_sched_data *q)
202{
203	int i;
204	u32 qlen = 0, prob = 0, totalpm = 0;
205	const struct sfb_bucket *b = &q->bins[q->slot].bins[0][0];
206
207	for (i = 0; i < SFB_LEVELS * SFB_NUMBUCKETS; i++) {
208		if (qlen < b->qlen)
209			qlen = b->qlen;
210		totalpm += b->p_mark;
211		if (prob < b->p_mark)
212			prob = b->p_mark;
213		b++;
214	}
215	*prob_r = prob;
216	*avgpm_r = totalpm / (SFB_LEVELS * SFB_NUMBUCKETS);
217	return qlen;
218}
219
220
221static void sfb_init_perturbation(u32 slot, struct sfb_sched_data *q)
222{
223	q->bins[slot].perturbation = prandom_u32();
224}
225
226static void sfb_swap_slot(struct sfb_sched_data *q)
227{
228	sfb_init_perturbation(q->slot, q);
229	q->slot ^= 1;
230	q->double_buffering = false;
231}
232
233/* Non elastic flows are allowed to use part of the bandwidth, expressed
234 * in "penalty_rate" packets per second, with "penalty_burst" burst
235 */
236static bool sfb_rate_limit(struct sk_buff *skb, struct sfb_sched_data *q)
237{
238	if (q->penalty_rate == 0 || q->penalty_burst == 0)
239		return true;
240
241	if (q->tokens_avail < 1) {
242		unsigned long age = min(10UL * HZ, jiffies - q->token_time);
243
244		q->tokens_avail = (age * q->penalty_rate) / HZ;
245		if (q->tokens_avail > q->penalty_burst)
246			q->tokens_avail = q->penalty_burst;
247		q->token_time = jiffies;
248		if (q->tokens_avail < 1)
249			return true;
250	}
251
252	q->tokens_avail--;
253	return false;
254}
255
256static bool sfb_classify(struct sk_buff *skb, struct tcf_proto *fl,
257			 int *qerr, u32 *salt)
258{
259	struct tcf_result res;
260	int result;
261
262	result = tc_classify(skb, fl, &res);
263	if (result >= 0) {
264#ifdef CONFIG_NET_CLS_ACT
265		switch (result) {
266		case TC_ACT_STOLEN:
267		case TC_ACT_QUEUED:
268			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
269		case TC_ACT_SHOT:
270			return false;
271		}
272#endif
273		*salt = TC_H_MIN(res.classid);
274		return true;
275	}
276	return false;
277}
278
279static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
280{
281
282	struct sfb_sched_data *q = qdisc_priv(sch);
283	struct Qdisc *child = q->qdisc;
284	struct tcf_proto *fl;
285	int i;
286	u32 p_min = ~0;
287	u32 minqlen = ~0;
288	u32 r, slot, salt, sfbhash;
289	int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
290	struct flow_keys keys;
291
292	if (unlikely(sch->q.qlen >= q->limit)) {
293		qdisc_qstats_overlimit(sch);
294		q->stats.queuedrop++;
295		goto drop;
296	}
297
298	if (q->rehash_interval > 0) {
299		unsigned long limit = q->rehash_time + q->rehash_interval;
300
301		if (unlikely(time_after(jiffies, limit))) {
302			sfb_swap_slot(q);
303			q->rehash_time = jiffies;
304		} else if (unlikely(!q->double_buffering && q->warmup_time > 0 &&
305				    time_after(jiffies, limit - q->warmup_time))) {
306			q->double_buffering = true;
307		}
308	}
309
310	fl = rcu_dereference_bh(q->filter_list);
311	if (fl) {
312		/* If using external classifiers, get result and record it. */
313		if (!sfb_classify(skb, fl, &ret, &salt))
314			goto other_drop;
315		keys.src = salt;
316		keys.dst = 0;
317		keys.ports = 0;
318	} else {
319		skb_flow_dissect(skb, &keys);
320	}
321
322	slot = q->slot;
323
324	sfbhash = jhash_3words((__force u32)keys.dst,
325			       (__force u32)keys.src,
326			       (__force u32)keys.ports,
327			       q->bins[slot].perturbation);
328	if (!sfbhash)
329		sfbhash = 1;
330	sfb_skb_cb(skb)->hashes[slot] = sfbhash;
331
332	for (i = 0; i < SFB_LEVELS; i++) {
333		u32 hash = sfbhash & SFB_BUCKET_MASK;
334		struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
335
336		sfbhash >>= SFB_BUCKET_SHIFT;
337		if (b->qlen == 0)
338			decrement_prob(b, q);
339		else if (b->qlen >= q->bin_size)
340			increment_prob(b, q);
341		if (minqlen > b->qlen)
342			minqlen = b->qlen;
343		if (p_min > b->p_mark)
344			p_min = b->p_mark;
345	}
346
347	slot ^= 1;
348	sfb_skb_cb(skb)->hashes[slot] = 0;
349
350	if (unlikely(minqlen >= q->max)) {
351		qdisc_qstats_overlimit(sch);
352		q->stats.bucketdrop++;
353		goto drop;
354	}
355
356	if (unlikely(p_min >= SFB_MAX_PROB)) {
357		/* Inelastic flow */
358		if (q->double_buffering) {
359			sfbhash = jhash_3words((__force u32)keys.dst,
360					       (__force u32)keys.src,
361					       (__force u32)keys.ports,
362					       q->bins[slot].perturbation);
363			if (!sfbhash)
364				sfbhash = 1;
365			sfb_skb_cb(skb)->hashes[slot] = sfbhash;
366
367			for (i = 0; i < SFB_LEVELS; i++) {
368				u32 hash = sfbhash & SFB_BUCKET_MASK;
369				struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
370
371				sfbhash >>= SFB_BUCKET_SHIFT;
372				if (b->qlen == 0)
373					decrement_prob(b, q);
374				else if (b->qlen >= q->bin_size)
375					increment_prob(b, q);
376			}
377		}
378		if (sfb_rate_limit(skb, q)) {
379			qdisc_qstats_overlimit(sch);
380			q->stats.penaltydrop++;
381			goto drop;
382		}
383		goto enqueue;
384	}
385
386	r = prandom_u32() & SFB_MAX_PROB;
387
388	if (unlikely(r < p_min)) {
389		if (unlikely(p_min > SFB_MAX_PROB / 2)) {
390			/* If we're marking that many packets, then either
391			 * this flow is unresponsive, or we're badly congested.
392			 * In either case, we want to start dropping packets.
393			 */
394			if (r < (p_min - SFB_MAX_PROB / 2) * 2) {
395				q->stats.earlydrop++;
396				goto drop;
397			}
398		}
399		if (INET_ECN_set_ce(skb)) {
400			q->stats.marked++;
401		} else {
402			q->stats.earlydrop++;
403			goto drop;
404		}
405	}
406
407enqueue:
408	ret = qdisc_enqueue(skb, child);
409	if (likely(ret == NET_XMIT_SUCCESS)) {
410		sch->q.qlen++;
411		increment_qlen(skb, q);
412	} else if (net_xmit_drop_count(ret)) {
413		q->stats.childdrop++;
414		qdisc_qstats_drop(sch);
415	}
416	return ret;
417
418drop:
419	qdisc_drop(skb, sch);
420	return NET_XMIT_CN;
421other_drop:
422	if (ret & __NET_XMIT_BYPASS)
423		qdisc_qstats_drop(sch);
424	kfree_skb(skb);
425	return ret;
426}
427
428static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
429{
430	struct sfb_sched_data *q = qdisc_priv(sch);
431	struct Qdisc *child = q->qdisc;
432	struct sk_buff *skb;
433
434	skb = child->dequeue(q->qdisc);
435
436	if (skb) {
437		qdisc_bstats_update(sch, skb);
438		sch->q.qlen--;
439		decrement_qlen(skb, q);
440	}
441
442	return skb;
443}
444
445static struct sk_buff *sfb_peek(struct Qdisc *sch)
446{
447	struct sfb_sched_data *q = qdisc_priv(sch);
448	struct Qdisc *child = q->qdisc;
449
450	return child->ops->peek(child);
451}
452
453/* No sfb_drop -- impossible since the child doesn't return the dropped skb. */
454
455static void sfb_reset(struct Qdisc *sch)
456{
457	struct sfb_sched_data *q = qdisc_priv(sch);
458
459	qdisc_reset(q->qdisc);
460	sch->q.qlen = 0;
461	q->slot = 0;
462	q->double_buffering = false;
463	sfb_zero_all_buckets(q);
464	sfb_init_perturbation(0, q);
465}
466
467static void sfb_destroy(struct Qdisc *sch)
468{
469	struct sfb_sched_data *q = qdisc_priv(sch);
470
471	tcf_destroy_chain(&q->filter_list);
472	qdisc_destroy(q->qdisc);
473}
474
475static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
476	[TCA_SFB_PARMS]	= { .len = sizeof(struct tc_sfb_qopt) },
477};
478
479static const struct tc_sfb_qopt sfb_default_ops = {
480	.rehash_interval = 600 * MSEC_PER_SEC,
481	.warmup_time = 60 * MSEC_PER_SEC,
482	.limit = 0,
483	.max = 25,
484	.bin_size = 20,
485	.increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
486	.decrement = (SFB_MAX_PROB + 3000) / 6000,
487	.penalty_rate = 10,
488	.penalty_burst = 20,
489};
490
491static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
492{
493	struct sfb_sched_data *q = qdisc_priv(sch);
494	struct Qdisc *child;
495	struct nlattr *tb[TCA_SFB_MAX + 1];
496	const struct tc_sfb_qopt *ctl = &sfb_default_ops;
497	u32 limit;
498	int err;
499
500	if (opt) {
501		err = nla_parse_nested(tb, TCA_SFB_MAX, opt, sfb_policy);
502		if (err < 0)
503			return -EINVAL;
504
505		if (tb[TCA_SFB_PARMS] == NULL)
506			return -EINVAL;
507
508		ctl = nla_data(tb[TCA_SFB_PARMS]);
509	}
510
511	limit = ctl->limit;
512	if (limit == 0)
513		limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
514
515	child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
516	if (IS_ERR(child))
517		return PTR_ERR(child);
518
519	sch_tree_lock(sch);
520
521	qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
522	qdisc_destroy(q->qdisc);
523	q->qdisc = child;
524
525	q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
526	q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
527	q->rehash_time = jiffies;
528	q->limit = limit;
529	q->increment = ctl->increment;
530	q->decrement = ctl->decrement;
531	q->max = ctl->max;
532	q->bin_size = ctl->bin_size;
533	q->penalty_rate = ctl->penalty_rate;
534	q->penalty_burst = ctl->penalty_burst;
535	q->tokens_avail = ctl->penalty_burst;
536	q->token_time = jiffies;
537
538	q->slot = 0;
539	q->double_buffering = false;
540	sfb_zero_all_buckets(q);
541	sfb_init_perturbation(0, q);
542	sfb_init_perturbation(1, q);
543
544	sch_tree_unlock(sch);
545
546	return 0;
547}
548
549static int sfb_init(struct Qdisc *sch, struct nlattr *opt)
550{
551	struct sfb_sched_data *q = qdisc_priv(sch);
552
553	q->qdisc = &noop_qdisc;
554	return sfb_change(sch, opt);
555}
556
557static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
558{
559	struct sfb_sched_data *q = qdisc_priv(sch);
560	struct nlattr *opts;
561	struct tc_sfb_qopt opt = {
562		.rehash_interval = jiffies_to_msecs(q->rehash_interval),
563		.warmup_time = jiffies_to_msecs(q->warmup_time),
564		.limit = q->limit,
565		.max = q->max,
566		.bin_size = q->bin_size,
567		.increment = q->increment,
568		.decrement = q->decrement,
569		.penalty_rate = q->penalty_rate,
570		.penalty_burst = q->penalty_burst,
571	};
572
573	sch->qstats.backlog = q->qdisc->qstats.backlog;
574	opts = nla_nest_start(skb, TCA_OPTIONS);
575	if (opts == NULL)
576		goto nla_put_failure;
577	if (nla_put(skb, TCA_SFB_PARMS, sizeof(opt), &opt))
578		goto nla_put_failure;
579	return nla_nest_end(skb, opts);
580
581nla_put_failure:
582	nla_nest_cancel(skb, opts);
583	return -EMSGSIZE;
584}
585
586static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
587{
588	struct sfb_sched_data *q = qdisc_priv(sch);
589	struct tc_sfb_xstats st = {
590		.earlydrop = q->stats.earlydrop,
591		.penaltydrop = q->stats.penaltydrop,
592		.bucketdrop = q->stats.bucketdrop,
593		.queuedrop = q->stats.queuedrop,
594		.childdrop = q->stats.childdrop,
595		.marked = q->stats.marked,
596	};
597
598	st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);
599
600	return gnet_stats_copy_app(d, &st, sizeof(st));
601}
602
603static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
604			  struct sk_buff *skb, struct tcmsg *tcm)
605{
606	return -ENOSYS;
607}
608
609static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
610		     struct Qdisc **old)
611{
612	struct sfb_sched_data *q = qdisc_priv(sch);
613
614	if (new == NULL)
615		new = &noop_qdisc;
616
617	sch_tree_lock(sch);
618	*old = q->qdisc;
619	q->qdisc = new;
620	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
621	qdisc_reset(*old);
622	sch_tree_unlock(sch);
623	return 0;
624}
625
626static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
627{
628	struct sfb_sched_data *q = qdisc_priv(sch);
629
630	return q->qdisc;
631}
632
633static unsigned long sfb_get(struct Qdisc *sch, u32 classid)
634{
635	return 1;
636}
637
638static void sfb_put(struct Qdisc *sch, unsigned long arg)
639{
640}
641
642static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
643			    struct nlattr **tca, unsigned long *arg)
644{
645	return -ENOSYS;
646}
647
648static int sfb_delete(struct Qdisc *sch, unsigned long cl)
649{
650	return -ENOSYS;
651}
652
653static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
654{
655	if (!walker->stop) {
656		if (walker->count >= walker->skip)
657			if (walker->fn(sch, 1, walker) < 0) {
658				walker->stop = 1;
659				return;
660			}
661		walker->count++;
662	}
663}
664
665static struct tcf_proto __rcu **sfb_find_tcf(struct Qdisc *sch,
666					     unsigned long cl)
667{
668	struct sfb_sched_data *q = qdisc_priv(sch);
669
670	if (cl)
671		return NULL;
672	return &q->filter_list;
673}
674
675static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
676			      u32 classid)
677{
678	return 0;
679}
680
681
682static const struct Qdisc_class_ops sfb_class_ops = {
683	.graft		=	sfb_graft,
684	.leaf		=	sfb_leaf,
685	.get		=	sfb_get,
686	.put		=	sfb_put,
687	.change		=	sfb_change_class,
688	.delete		=	sfb_delete,
689	.walk		=	sfb_walk,
690	.tcf_chain	=	sfb_find_tcf,
691	.bind_tcf	=	sfb_bind,
692	.unbind_tcf	=	sfb_put,
693	.dump		=	sfb_dump_class,
694};
695
696static struct Qdisc_ops sfb_qdisc_ops __read_mostly = {
697	.id		=	"sfb",
698	.priv_size	=	sizeof(struct sfb_sched_data),
699	.cl_ops		=	&sfb_class_ops,
700	.enqueue	=	sfb_enqueue,
701	.dequeue	=	sfb_dequeue,
702	.peek		=	sfb_peek,
703	.init		=	sfb_init,
704	.reset		=	sfb_reset,
705	.destroy	=	sfb_destroy,
706	.change		=	sfb_change,
707	.dump		=	sfb_dump,
708	.dump_stats	=	sfb_dump_stats,
709	.owner		=	THIS_MODULE,
710};
711
712static int __init sfb_module_init(void)
713{
714	return register_qdisc(&sfb_qdisc_ops);
715}
716
717static void __exit sfb_module_exit(void)
718{
719	unregister_qdisc(&sfb_qdisc_ops);
720}
721
722module_init(sfb_module_init)
723module_exit(sfb_module_exit)
724
725MODULE_DESCRIPTION("Stochastic Fair Blue queue discipline");
726MODULE_AUTHOR("Juliusz Chroboczek");
727MODULE_AUTHOR("Eric Dumazet");
728MODULE_LICENSE("GPL");
729