xref: /linux/net/sched/sch_sfb.c (revision f3a8b6645dc2e60d11f20c1c23afd964ff4e55ae) 
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 
30 /*
31  * SFB uses two B[l][n] : L x N arrays of bins (L levels, N bins per level)
32  * This implementation uses L = 8 and N = 16
33  * This permits us to split one 32bit hash (provided per packet by rxhash or
34  * external classifier) into 8 subhashes of 4 bits.
35  */
36 #define SFB_BUCKET_SHIFT 4
37 #define SFB_NUMBUCKETS	(1 << SFB_BUCKET_SHIFT) /* N bins per Level */
38 #define SFB_BUCKET_MASK (SFB_NUMBUCKETS - 1)
39 #define SFB_LEVELS	(32 / SFB_BUCKET_SHIFT) /* L */
40 
41 /* SFB algo uses a virtual queue, named "bin" */
42 struct sfb_bucket {
43 	u16		qlen; /* length of virtual queue */
44 	u16		p_mark; /* marking probability */
45 };
46 
47 /* We use a double buffering right before hash change
48  * (Section 4.4 of SFB reference : moving hash functions)
49  */
50 struct sfb_bins {
51 	u32		  perturbation; /* jhash perturbation */
52 	struct sfb_bucket bins[SFB_LEVELS][SFB_NUMBUCKETS];
53 };
54 
55 struct sfb_sched_data {
56 	struct Qdisc	*qdisc;
57 	struct tcf_proto __rcu *filter_list;
58 	unsigned long	rehash_interval;
59 	unsigned long	warmup_time;	/* double buffering warmup time in jiffies */
60 	u32		max;
61 	u32		bin_size;	/* maximum queue length per bin */
62 	u32		increment;	/* d1 */
63 	u32		decrement;	/* d2 */
64 	u32		limit;		/* HARD maximal queue length */
65 	u32		penalty_rate;
66 	u32		penalty_burst;
67 	u32		tokens_avail;
68 	unsigned long	rehash_time;
69 	unsigned long	token_time;
70 
71 	u8		slot;		/* current active bins (0 or 1) */
72 	bool		double_buffering;
73 	struct sfb_bins bins[2];
74 
75 	struct {
76 		u32	earlydrop;
77 		u32	penaltydrop;
78 		u32	bucketdrop;
79 		u32	queuedrop;
80 		u32	childdrop;	/* drops in child qdisc */
81 		u32	marked;		/* ECN mark */
82 	} stats;
83 };
84 
85 /*
86  * Each queued skb might be hashed on one or two bins
87  * We store in skb_cb the two hash values.
88  * (A zero value means double buffering was not used)
89  */
90 struct sfb_skb_cb {
91 	u32 hashes[2];
92 };
93 
94 static inline struct sfb_skb_cb *sfb_skb_cb(const struct sk_buff *skb)
95 {
96 	qdisc_cb_private_validate(skb, sizeof(struct sfb_skb_cb));
97 	return (struct sfb_skb_cb *)qdisc_skb_cb(skb)->data;
98 }
99 
100 /*
101  * If using 'internal' SFB flow classifier, hash comes from skb rxhash
102  * If using external classifier, hash comes from the classid.
103  */
104 static u32 sfb_hash(const struct sk_buff *skb, u32 slot)
105 {
106 	return sfb_skb_cb(skb)->hashes[slot];
107 }
108 
109 /* Probabilities are coded as Q0.16 fixed-point values,
110  * with 0xFFFF representing 65535/65536 (almost 1.0)
111  * Addition and subtraction are saturating in [0, 65535]
112  */
113 static u32 prob_plus(u32 p1, u32 p2)
114 {
115 	u32 res = p1 + p2;
116 
117 	return min_t(u32, res, SFB_MAX_PROB);
118 }
119 
120 static u32 prob_minus(u32 p1, u32 p2)
121 {
122 	return p1 > p2 ? p1 - p2 : 0;
123 }
124 
125 static void increment_one_qlen(u32 sfbhash, u32 slot, struct sfb_sched_data *q)
126 {
127 	int i;
128 	struct sfb_bucket *b = &q->bins[slot].bins[0][0];
129 
130 	for (i = 0; i < SFB_LEVELS; i++) {
131 		u32 hash = sfbhash & SFB_BUCKET_MASK;
132 
133 		sfbhash >>= SFB_BUCKET_SHIFT;
134 		if (b[hash].qlen < 0xFFFF)
135 			b[hash].qlen++;
136 		b += SFB_NUMBUCKETS; /* next level */
137 	}
138 }
139 
140 static void increment_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
141 {
142 	u32 sfbhash;
143 
144 	sfbhash = sfb_hash(skb, 0);
145 	if (sfbhash)
146 		increment_one_qlen(sfbhash, 0, q);
147 
148 	sfbhash = sfb_hash(skb, 1);
149 	if (sfbhash)
150 		increment_one_qlen(sfbhash, 1, q);
151 }
152 
153 static void decrement_one_qlen(u32 sfbhash, u32 slot,
154 			       struct sfb_sched_data *q)
155 {
156 	int i;
157 	struct sfb_bucket *b = &q->bins[slot].bins[0][0];
158 
159 	for (i = 0; i < SFB_LEVELS; i++) {
160 		u32 hash = sfbhash & SFB_BUCKET_MASK;
161 
162 		sfbhash >>= SFB_BUCKET_SHIFT;
163 		if (b[hash].qlen > 0)
164 			b[hash].qlen--;
165 		b += SFB_NUMBUCKETS; /* next level */
166 	}
167 }
168 
169 static void decrement_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
170 {
171 	u32 sfbhash;
172 
173 	sfbhash = sfb_hash(skb, 0);
174 	if (sfbhash)
175 		decrement_one_qlen(sfbhash, 0, q);
176 
177 	sfbhash = sfb_hash(skb, 1);
178 	if (sfbhash)
179 		decrement_one_qlen(sfbhash, 1, q);
180 }
181 
182 static void decrement_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
183 {
184 	b->p_mark = prob_minus(b->p_mark, q->decrement);
185 }
186 
187 static void increment_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
188 {
189 	b->p_mark = prob_plus(b->p_mark, q->increment);
190 }
191 
192 static void sfb_zero_all_buckets(struct sfb_sched_data *q)
193 {
194 	memset(&q->bins, 0, sizeof(q->bins));
195 }
196 
197 /*
198  * compute max qlen, max p_mark, and avg p_mark
199  */
200 static u32 sfb_compute_qlen(u32 *prob_r, u32 *avgpm_r, const struct sfb_sched_data *q)
201 {
202 	int i;
203 	u32 qlen = 0, prob = 0, totalpm = 0;
204 	const struct sfb_bucket *b = &q->bins[q->slot].bins[0][0];
205 
206 	for (i = 0; i < SFB_LEVELS * SFB_NUMBUCKETS; i++) {
207 		if (qlen < b->qlen)
208 			qlen = b->qlen;
209 		totalpm += b->p_mark;
210 		if (prob < b->p_mark)
211 			prob = b->p_mark;
212 		b++;
213 	}
214 	*prob_r = prob;
215 	*avgpm_r = totalpm / (SFB_LEVELS * SFB_NUMBUCKETS);
216 	return qlen;
217 }
218 
219 
220 static void sfb_init_perturbation(u32 slot, struct sfb_sched_data *q)
221 {
222 	q->bins[slot].perturbation = prandom_u32();
223 }
224 
225 static void sfb_swap_slot(struct sfb_sched_data *q)
226 {
227 	sfb_init_perturbation(q->slot, q);
228 	q->slot ^= 1;
229 	q->double_buffering = false;
230 }
231 
232 /* Non elastic flows are allowed to use part of the bandwidth, expressed
233  * in "penalty_rate" packets per second, with "penalty_burst" burst
234  */
235 static bool sfb_rate_limit(struct sk_buff *skb, struct sfb_sched_data *q)
236 {
237 	if (q->penalty_rate == 0 || q->penalty_burst == 0)
238 		return true;
239 
240 	if (q->tokens_avail < 1) {
241 		unsigned long age = min(10UL * HZ, jiffies - q->token_time);
242 
243 		q->tokens_avail = (age * q->penalty_rate) / HZ;
244 		if (q->tokens_avail > q->penalty_burst)
245 			q->tokens_avail = q->penalty_burst;
246 		q->token_time = jiffies;
247 		if (q->tokens_avail < 1)
248 			return true;
249 	}
250 
251 	q->tokens_avail--;
252 	return false;
253 }
254 
255 static bool sfb_classify(struct sk_buff *skb, struct tcf_proto *fl,
256 			 int *qerr, u32 *salt)
257 {
258 	struct tcf_result res;
259 	int result;
260 
261 	result = tc_classify(skb, fl, &res, false);
262 	if (result >= 0) {
263 #ifdef CONFIG_NET_CLS_ACT
264 		switch (result) {
265 		case TC_ACT_STOLEN:
266 		case TC_ACT_QUEUED:
267 			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
268 		case TC_ACT_SHOT:
269 			return false;
270 		}
271 #endif
272 		*salt = TC_H_MIN(res.classid);
273 		return true;
274 	}
275 	return false;
276 }
277 
278 static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
279 		       struct sk_buff **to_free)
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, sfbhash;
289 	u32 slot = q->slot;
290 	int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
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 		u32 salt;
313 
314 		/* If using external classifiers, get result and record it. */
315 		if (!sfb_classify(skb, fl, &ret, &salt))
316 			goto other_drop;
317 		sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
318 	} else {
319 		sfbhash = skb_get_hash_perturb(skb, q->bins[slot].perturbation);
320 	}
321 
322 
323 	if (!sfbhash)
324 		sfbhash = 1;
325 	sfb_skb_cb(skb)->hashes[slot] = sfbhash;
326 
327 	for (i = 0; i < SFB_LEVELS; i++) {
328 		u32 hash = sfbhash & SFB_BUCKET_MASK;
329 		struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
330 
331 		sfbhash >>= SFB_BUCKET_SHIFT;
332 		if (b->qlen == 0)
333 			decrement_prob(b, q);
334 		else if (b->qlen >= q->bin_size)
335 			increment_prob(b, q);
336 		if (minqlen > b->qlen)
337 			minqlen = b->qlen;
338 		if (p_min > b->p_mark)
339 			p_min = b->p_mark;
340 	}
341 
342 	slot ^= 1;
343 	sfb_skb_cb(skb)->hashes[slot] = 0;
344 
345 	if (unlikely(minqlen >= q->max)) {
346 		qdisc_qstats_overlimit(sch);
347 		q->stats.bucketdrop++;
348 		goto drop;
349 	}
350 
351 	if (unlikely(p_min >= SFB_MAX_PROB)) {
352 		/* Inelastic flow */
353 		if (q->double_buffering) {
354 			sfbhash = skb_get_hash_perturb(skb,
355 			    q->bins[slot].perturbation);
356 			if (!sfbhash)
357 				sfbhash = 1;
358 			sfb_skb_cb(skb)->hashes[slot] = sfbhash;
359 
360 			for (i = 0; i < SFB_LEVELS; i++) {
361 				u32 hash = sfbhash & SFB_BUCKET_MASK;
362 				struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
363 
364 				sfbhash >>= SFB_BUCKET_SHIFT;
365 				if (b->qlen == 0)
366 					decrement_prob(b, q);
367 				else if (b->qlen >= q->bin_size)
368 					increment_prob(b, q);
369 			}
370 		}
371 		if (sfb_rate_limit(skb, q)) {
372 			qdisc_qstats_overlimit(sch);
373 			q->stats.penaltydrop++;
374 			goto drop;
375 		}
376 		goto enqueue;
377 	}
378 
379 	r = prandom_u32() & SFB_MAX_PROB;
380 
381 	if (unlikely(r < p_min)) {
382 		if (unlikely(p_min > SFB_MAX_PROB / 2)) {
383 			/* If we're marking that many packets, then either
384 			 * this flow is unresponsive, or we're badly congested.
385 			 * In either case, we want to start dropping packets.
386 			 */
387 			if (r < (p_min - SFB_MAX_PROB / 2) * 2) {
388 				q->stats.earlydrop++;
389 				goto drop;
390 			}
391 		}
392 		if (INET_ECN_set_ce(skb)) {
393 			q->stats.marked++;
394 		} else {
395 			q->stats.earlydrop++;
396 			goto drop;
397 		}
398 	}
399 
400 enqueue:
401 	ret = qdisc_enqueue(skb, child, to_free);
402 	if (likely(ret == NET_XMIT_SUCCESS)) {
403 		qdisc_qstats_backlog_inc(sch, skb);
404 		sch->q.qlen++;
405 		increment_qlen(skb, q);
406 	} else if (net_xmit_drop_count(ret)) {
407 		q->stats.childdrop++;
408 		qdisc_qstats_drop(sch);
409 	}
410 	return ret;
411 
412 drop:
413 	qdisc_drop(skb, sch, to_free);
414 	return NET_XMIT_CN;
415 other_drop:
416 	if (ret & __NET_XMIT_BYPASS)
417 		qdisc_qstats_drop(sch);
418 	kfree_skb(skb);
419 	return ret;
420 }
421 
422 static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
423 {
424 	struct sfb_sched_data *q = qdisc_priv(sch);
425 	struct Qdisc *child = q->qdisc;
426 	struct sk_buff *skb;
427 
428 	skb = child->dequeue(q->qdisc);
429 
430 	if (skb) {
431 		qdisc_bstats_update(sch, skb);
432 		qdisc_qstats_backlog_dec(sch, skb);
433 		sch->q.qlen--;
434 		decrement_qlen(skb, q);
435 	}
436 
437 	return skb;
438 }
439 
440 static struct sk_buff *sfb_peek(struct Qdisc *sch)
441 {
442 	struct sfb_sched_data *q = qdisc_priv(sch);
443 	struct Qdisc *child = q->qdisc;
444 
445 	return child->ops->peek(child);
446 }
447 
448 /* No sfb_drop -- impossible since the child doesn't return the dropped skb. */
449 
450 static void sfb_reset(struct Qdisc *sch)
451 {
452 	struct sfb_sched_data *q = qdisc_priv(sch);
453 
454 	qdisc_reset(q->qdisc);
455 	sch->qstats.backlog = 0;
456 	sch->q.qlen = 0;
457 	q->slot = 0;
458 	q->double_buffering = false;
459 	sfb_zero_all_buckets(q);
460 	sfb_init_perturbation(0, q);
461 }
462 
463 static void sfb_destroy(struct Qdisc *sch)
464 {
465 	struct sfb_sched_data *q = qdisc_priv(sch);
466 
467 	tcf_destroy_chain(&q->filter_list);
468 	qdisc_destroy(q->qdisc);
469 }
470 
471 static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
472 	[TCA_SFB_PARMS]	= { .len = sizeof(struct tc_sfb_qopt) },
473 };
474 
475 static const struct tc_sfb_qopt sfb_default_ops = {
476 	.rehash_interval = 600 * MSEC_PER_SEC,
477 	.warmup_time = 60 * MSEC_PER_SEC,
478 	.limit = 0,
479 	.max = 25,
480 	.bin_size = 20,
481 	.increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
482 	.decrement = (SFB_MAX_PROB + 3000) / 6000,
483 	.penalty_rate = 10,
484 	.penalty_burst = 20,
485 };
486 
487 static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
488 {
489 	struct sfb_sched_data *q = qdisc_priv(sch);
490 	struct Qdisc *child;
491 	struct nlattr *tb[TCA_SFB_MAX + 1];
492 	const struct tc_sfb_qopt *ctl = &sfb_default_ops;
493 	u32 limit;
494 	int err;
495 
496 	if (opt) {
497 		err = nla_parse_nested(tb, TCA_SFB_MAX, opt, sfb_policy);
498 		if (err < 0)
499 			return -EINVAL;
500 
501 		if (tb[TCA_SFB_PARMS] == NULL)
502 			return -EINVAL;
503 
504 		ctl = nla_data(tb[TCA_SFB_PARMS]);
505 	}
506 
507 	limit = ctl->limit;
508 	if (limit == 0)
509 		limit = qdisc_dev(sch)->tx_queue_len;
510 
511 	child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
512 	if (IS_ERR(child))
513 		return PTR_ERR(child);
514 
515 	sch_tree_lock(sch);
516 
517 	qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
518 				  q->qdisc->qstats.backlog);
519 	qdisc_destroy(q->qdisc);
520 	q->qdisc = child;
521 
522 	q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
523 	q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
524 	q->rehash_time = jiffies;
525 	q->limit = limit;
526 	q->increment = ctl->increment;
527 	q->decrement = ctl->decrement;
528 	q->max = ctl->max;
529 	q->bin_size = ctl->bin_size;
530 	q->penalty_rate = ctl->penalty_rate;
531 	q->penalty_burst = ctl->penalty_burst;
532 	q->tokens_avail = ctl->penalty_burst;
533 	q->token_time = jiffies;
534 
535 	q->slot = 0;
536 	q->double_buffering = false;
537 	sfb_zero_all_buckets(q);
538 	sfb_init_perturbation(0, q);
539 	sfb_init_perturbation(1, q);
540 
541 	sch_tree_unlock(sch);
542 
543 	return 0;
544 }
545 
546 static int sfb_init(struct Qdisc *sch, struct nlattr *opt)
547 {
548 	struct sfb_sched_data *q = qdisc_priv(sch);
549 
550 	q->qdisc = &noop_qdisc;
551 	return sfb_change(sch, opt);
552 }
553 
554 static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
555 {
556 	struct sfb_sched_data *q = qdisc_priv(sch);
557 	struct nlattr *opts;
558 	struct tc_sfb_qopt opt = {
559 		.rehash_interval = jiffies_to_msecs(q->rehash_interval),
560 		.warmup_time = jiffies_to_msecs(q->warmup_time),
561 		.limit = q->limit,
562 		.max = q->max,
563 		.bin_size = q->bin_size,
564 		.increment = q->increment,
565 		.decrement = q->decrement,
566 		.penalty_rate = q->penalty_rate,
567 		.penalty_burst = q->penalty_burst,
568 	};
569 
570 	sch->qstats.backlog = q->qdisc->qstats.backlog;
571 	opts = nla_nest_start(skb, TCA_OPTIONS);
572 	if (opts == NULL)
573 		goto nla_put_failure;
574 	if (nla_put(skb, TCA_SFB_PARMS, sizeof(opt), &opt))
575 		goto nla_put_failure;
576 	return nla_nest_end(skb, opts);
577 
578 nla_put_failure:
579 	nla_nest_cancel(skb, opts);
580 	return -EMSGSIZE;
581 }
582 
583 static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
584 {
585 	struct sfb_sched_data *q = qdisc_priv(sch);
586 	struct tc_sfb_xstats st = {
587 		.earlydrop = q->stats.earlydrop,
588 		.penaltydrop = q->stats.penaltydrop,
589 		.bucketdrop = q->stats.bucketdrop,
590 		.queuedrop = q->stats.queuedrop,
591 		.childdrop = q->stats.childdrop,
592 		.marked = q->stats.marked,
593 	};
594 
595 	st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);
596 
597 	return gnet_stats_copy_app(d, &st, sizeof(st));
598 }
599 
600 static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
601 			  struct sk_buff *skb, struct tcmsg *tcm)
602 {
603 	return -ENOSYS;
604 }
605 
606 static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
607 		     struct Qdisc **old)
608 {
609 	struct sfb_sched_data *q = qdisc_priv(sch);
610 
611 	if (new == NULL)
612 		new = &noop_qdisc;
613 
614 	*old = qdisc_replace(sch, new, &q->qdisc);
615 	return 0;
616 }
617 
618 static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
619 {
620 	struct sfb_sched_data *q = qdisc_priv(sch);
621 
622 	return q->qdisc;
623 }
624 
625 static unsigned long sfb_get(struct Qdisc *sch, u32 classid)
626 {
627 	return 1;
628 }
629 
630 static void sfb_put(struct Qdisc *sch, unsigned long arg)
631 {
632 }
633 
634 static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
635 			    struct nlattr **tca, unsigned long *arg)
636 {
637 	return -ENOSYS;
638 }
639 
640 static int sfb_delete(struct Qdisc *sch, unsigned long cl)
641 {
642 	return -ENOSYS;
643 }
644 
645 static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
646 {
647 	if (!walker->stop) {
648 		if (walker->count >= walker->skip)
649 			if (walker->fn(sch, 1, walker) < 0) {
650 				walker->stop = 1;
651 				return;
652 			}
653 		walker->count++;
654 	}
655 }
656 
657 static struct tcf_proto __rcu **sfb_find_tcf(struct Qdisc *sch,
658 					     unsigned long cl)
659 {
660 	struct sfb_sched_data *q = qdisc_priv(sch);
661 
662 	if (cl)
663 		return NULL;
664 	return &q->filter_list;
665 }
666 
667 static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
668 			      u32 classid)
669 {
670 	return 0;
671 }
672 
673 
674 static const struct Qdisc_class_ops sfb_class_ops = {
675 	.graft		=	sfb_graft,
676 	.leaf		=	sfb_leaf,
677 	.get		=	sfb_get,
678 	.put		=	sfb_put,
679 	.change		=	sfb_change_class,
680 	.delete		=	sfb_delete,
681 	.walk		=	sfb_walk,
682 	.tcf_chain	=	sfb_find_tcf,
683 	.bind_tcf	=	sfb_bind,
684 	.unbind_tcf	=	sfb_put,
685 	.dump		=	sfb_dump_class,
686 };
687 
688 static struct Qdisc_ops sfb_qdisc_ops __read_mostly = {
689 	.id		=	"sfb",
690 	.priv_size	=	sizeof(struct sfb_sched_data),
691 	.cl_ops		=	&sfb_class_ops,
692 	.enqueue	=	sfb_enqueue,
693 	.dequeue	=	sfb_dequeue,
694 	.peek		=	sfb_peek,
695 	.init		=	sfb_init,
696 	.reset		=	sfb_reset,
697 	.destroy	=	sfb_destroy,
698 	.change		=	sfb_change,
699 	.dump		=	sfb_dump,
700 	.dump_stats	=	sfb_dump_stats,
701 	.owner		=	THIS_MODULE,
702 };
703 
704 static int __init sfb_module_init(void)
705 {
706 	return register_qdisc(&sfb_qdisc_ops);
707 }
708 
709 static void __exit sfb_module_exit(void)
710 {
711 	unregister_qdisc(&sfb_qdisc_ops);
712 }
713 
714 module_init(sfb_module_init)
715 module_exit(sfb_module_exit)
716 
717 MODULE_DESCRIPTION("Stochastic Fair Blue queue discipline");
718 MODULE_AUTHOR("Juliusz Chroboczek");
719 MODULE_AUTHOR("Eric Dumazet");
720 MODULE_LICENSE("GPL");
721