net/sched/sch_sfb.c

   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 *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         BUILD_BUG_ON(sizeof(skb->cb) <
  97                 sizeof(struct qdisc_skb_cb) + 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  */
 105 static 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  */
 114 static 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
 121 static u32 prob_minus(u32 p1, u32 p2)
 122 {
 123         return p1 > p2 ? p1 - p2 : 0;
 124 }
 125
 126 static 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
 141 static 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
 154 static 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
 170 static 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
 183 static 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
 188 static 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
 193 static 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  */
 201 static 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
 221 static void sfb_init_perturbation(u32 slot, struct sfb_sched_data *q)
 222 {
 223         q->bins[slot].perturbation = net_random();
 224 }
 225
 226 static 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  */
 236 static 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
 256 static bool sfb_classify(struct sk_buff *skb, struct sfb_sched_data *q,
 257                          int *qerr, u32 *salt)
 258 {
 259         struct tcf_result res;
 260         int result;
 261
 262         result = tc_classify(skb, q->filter_list, &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
 279 static 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         int i;
 285         u32 p_min = ~0;
 286         u32 minqlen = ~0;
 287         u32 r, slot, salt, sfbhash;
 288         int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 289
 290         if (q->rehash_interval > 0) {
 291                 unsigned long limit = q->rehash_time + q->rehash_interval;
 292
 293                 if (unlikely(time_after(jiffies, limit))) {
 294                         sfb_swap_slot(q);
 295                         q->rehash_time = jiffies;
 296                 } else if (unlikely(!q->double_buffering && q->warmup_time > 0 &&
 297                                     time_after(jiffies, limit - q->warmup_time))) {
 298                         q->double_buffering = true;
 299                 }
 300         }
 301
 302         if (q->filter_list) {
 303                 /* If using external classifiers, get result and record it. */
 304                 if (!sfb_classify(skb, q, &ret, &salt))
 305                         goto other_drop;
 306         } else {
 307                 salt = skb_get_rxhash(skb);
 308         }
 309
 310         slot = q->slot;
 311
 312         sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
 313         if (!sfbhash)
 314                 sfbhash = 1;
 315         sfb_skb_cb(skb)->hashes[slot] = sfbhash;
 316
 317         for (i = 0; i < SFB_LEVELS; i++) {
 318                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 319                 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
 320
 321                 sfbhash >>= SFB_BUCKET_SHIFT;
 322                 if (b->qlen == 0)
 323                         decrement_prob(b, q);
 324                 else if (b->qlen >= q->bin_size)
 325                         increment_prob(b, q);
 326                 if (minqlen > b->qlen)
 327                         minqlen = b->qlen;
 328                 if (p_min > b->p_mark)
 329                         p_min = b->p_mark;
 330         }
 331
 332         slot ^= 1;
 333         sfb_skb_cb(skb)->hashes[slot] = 0;
 334
 335         if (unlikely(minqlen >= q->max || sch->q.qlen >= q->limit)) {
 336                 sch->qstats.overlimits++;
 337                 if (minqlen >= q->max)
 338                         q->stats.bucketdrop++;
 339                 else
 340                         q->stats.queuedrop++;
 341                 goto drop;
 342         }
 343
 344         if (unlikely(p_min >= SFB_MAX_PROB)) {
 345                 /* Inelastic flow */
 346                 if (q->double_buffering) {
 347                         sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
 348                         if (!sfbhash)
 349                                 sfbhash = 1;
 350                         sfb_skb_cb(skb)->hashes[slot] = sfbhash;
 351
 352                         for (i = 0; i < SFB_LEVELS; i++) {
 353                                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 354                                 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
 355
 356                                 sfbhash >>= SFB_BUCKET_SHIFT;
 357                                 if (b->qlen == 0)
 358                                         decrement_prob(b, q);
 359                                 else if (b->qlen >= q->bin_size)
 360                                         increment_prob(b, q);
 361                         }
 362                 }
 363                 if (sfb_rate_limit(skb, q)) {
 364                         sch->qstats.overlimits++;
 365                         q->stats.penaltydrop++;
 366                         goto drop;
 367                 }
 368                 goto enqueue;
 369         }
 370
 371         r = net_random() & SFB_MAX_PROB;
 372
 373         if (unlikely(r < p_min)) {
 374                 if (unlikely(p_min > SFB_MAX_PROB / 2)) {
 375                         /* If we're marking that many packets, then either
 376                          * this flow is unresponsive, or we're badly congested.
 377                          * In either case, we want to start dropping packets.
 378                          */
 379                         if (r < (p_min - SFB_MAX_PROB / 2) * 2) {
 380                                 q->stats.earlydrop++;
 381                                 goto drop;
 382                         }
 383                 }
 384                 if (INET_ECN_set_ce(skb)) {
 385                         q->stats.marked++;
 386                 } else {
 387                         q->stats.earlydrop++;
 388                         goto drop;
 389                 }
 390         }
 391
 392 enqueue:
 393         ret = qdisc_enqueue(skb, child);
 394         if (likely(ret == NET_XMIT_SUCCESS)) {
 395                 sch->q.qlen++;
 396                 increment_qlen(skb, q);
 397         } else if (net_xmit_drop_count(ret)) {
 398                 q->stats.childdrop++;
 399                 sch->qstats.drops++;
 400         }
 401         return ret;
 402
 403 drop:
 404         qdisc_drop(skb, sch);
 405         return NET_XMIT_CN;
 406 other_drop:
 407         if (ret & __NET_XMIT_BYPASS)
 408                 sch->qstats.drops++;
 409         kfree_skb(skb);
 410         return ret;
 411 }
 412
 413 static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
 414 {
 415         struct sfb_sched_data *q = qdisc_priv(sch);
 416         struct Qdisc *child = q->qdisc;
 417         struct sk_buff *skb;
 418
 419         skb = child->dequeue(q->qdisc);
 420
 421         if (skb) {
 422                 qdisc_bstats_update(sch, skb);
 423                 sch->q.qlen--;
 424                 decrement_qlen(skb, q);
 425         }
 426
 427         return skb;
 428 }
 429
 430 static struct sk_buff *sfb_peek(struct Qdisc *sch)
 431 {
 432         struct sfb_sched_data *q = qdisc_priv(sch);
 433         struct Qdisc *child = q->qdisc;
 434
 435         return child->ops->peek(child);
 436 }
 437
 438 /* No sfb_drop -- impossible since the child doesn't return the dropped skb. */
 439
 440 static void sfb_reset(struct Qdisc *sch)
 441 {
 442         struct sfb_sched_data *q = qdisc_priv(sch);
 443
 444         qdisc_reset(q->qdisc);
 445         sch->q.qlen = 0;
 446         q->slot = 0;
 447         q->double_buffering = false;
 448         sfb_zero_all_buckets(q);
 449         sfb_init_perturbation(0, q);
 450 }
 451
 452 static void sfb_destroy(struct Qdisc *sch)
 453 {
 454         struct sfb_sched_data *q = qdisc_priv(sch);
 455
 456         tcf_destroy_chain(&q->filter_list);
 457         qdisc_destroy(q->qdisc);
 458 }
 459
 460 static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
 461         [TCA_SFB_PARMS] = { .len = sizeof(struct tc_sfb_qopt) },
 462 };
 463
 464 static const struct tc_sfb_qopt sfb_default_ops = {
 465         .rehash_interval = 600 * MSEC_PER_SEC,
 466         .warmup_time = 60 * MSEC_PER_SEC,
 467         .limit = 0,
 468         .max = 25,
 469         .bin_size = 20,
 470         .increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
 471         .decrement = (SFB_MAX_PROB + 3000) / 6000,
 472         .penalty_rate = 10,
 473         .penalty_burst = 20,
 474 };
 475
 476 static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
 477 {
 478         struct sfb_sched_data *q = qdisc_priv(sch);
 479         struct Qdisc *child;
 480         struct nlattr *tb[TCA_SFB_MAX + 1];
 481         const struct tc_sfb_qopt *ctl = &sfb_default_ops;
 482         u32 limit;
 483         int err;
 484
 485         if (opt) {
 486                 err = nla_parse_nested(tb, TCA_SFB_MAX, opt, sfb_policy);
 487                 if (err < 0)
 488                         return -EINVAL;
 489
 490                 if (tb[TCA_SFB_PARMS] == NULL)
 491                         return -EINVAL;
 492
 493                 ctl = nla_data(tb[TCA_SFB_PARMS]);
 494         }
 495
 496         limit = ctl->limit;
 497         if (limit == 0)
 498                 limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
 499
 500         child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
 501         if (IS_ERR(child))
 502                 return PTR_ERR(child);
 503
 504         sch_tree_lock(sch);
 505
 506         qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
 507         qdisc_destroy(q->qdisc);
 508         q->qdisc = child;
 509
 510         q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
 511         q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
 512         q->rehash_time = jiffies;
 513         q->limit = limit;
 514         q->increment = ctl->increment;
 515         q->decrement = ctl->decrement;
 516         q->max = ctl->max;
 517         q->bin_size = ctl->bin_size;
 518         q->penalty_rate = ctl->penalty_rate;
 519         q->penalty_burst = ctl->penalty_burst;
 520         q->tokens_avail = ctl->penalty_burst;
 521         q->token_time = jiffies;
 522
 523         q->slot = 0;
 524         q->double_buffering = false;
 525         sfb_zero_all_buckets(q);
 526         sfb_init_perturbation(0, q);
 527         sfb_init_perturbation(1, q);
 528
 529         sch_tree_unlock(sch);
 530
 531         return 0;
 532 }
 533
 534 static int sfb_init(struct Qdisc *sch, struct nlattr *opt)
 535 {
 536         struct sfb_sched_data *q = qdisc_priv(sch);
 537
 538         q->qdisc = &noop_qdisc;
 539         return sfb_change(sch, opt);
 540 }
 541
 542 static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
 543 {
 544         struct sfb_sched_data *q = qdisc_priv(sch);
 545         struct nlattr *opts;
 546         struct tc_sfb_qopt opt = {
 547                 .rehash_interval = jiffies_to_msecs(q->rehash_interval),
 548                 .warmup_time = jiffies_to_msecs(q->warmup_time),
 549                 .limit = q->limit,
 550                 .max = q->max,
 551                 .bin_size = q->bin_size,
 552                 .increment = q->increment,
 553                 .decrement = q->decrement,
 554                 .penalty_rate = q->penalty_rate,
 555                 .penalty_burst = q->penalty_burst,
 556         };
 557
 558         sch->qstats.backlog = q->qdisc->qstats.backlog;
 559         opts = nla_nest_start(skb, TCA_OPTIONS);
 560         NLA_PUT(skb, TCA_SFB_PARMS, sizeof(opt), &opt);
 561         return nla_nest_end(skb, opts);
 562
 563 nla_put_failure:
 564         nla_nest_cancel(skb, opts);
 565         return -EMSGSIZE;
 566 }
 567
 568 static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 569 {
 570         struct sfb_sched_data *q = qdisc_priv(sch);
 571         struct tc_sfb_xstats st = {
 572                 .earlydrop = q->stats.earlydrop,
 573                 .penaltydrop = q->stats.penaltydrop,
 574                 .bucketdrop = q->stats.bucketdrop,
 575                 .queuedrop = q->stats.queuedrop,
 576                 .childdrop = q->stats.childdrop,
 577                 .marked = q->stats.marked,
 578         };
 579
 580         st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);
 581
 582         return gnet_stats_copy_app(d, &st, sizeof(st));
 583 }
 584
 585 static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
 586                           struct sk_buff *skb, struct tcmsg *tcm)
 587 {
 588         return -ENOSYS;
 589 }
 590
 591 static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 592                      struct Qdisc **old)
 593 {
 594         struct sfb_sched_data *q = qdisc_priv(sch);
 595
 596         if (new == NULL)
 597                 new = &noop_qdisc;
 598
 599         sch_tree_lock(sch);
 600         *old = q->qdisc;
 601         q->qdisc = new;
 602         qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
 603         qdisc_reset(*old);
 604         sch_tree_unlock(sch);
 605         return 0;
 606 }
 607
 608 static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
 609 {
 610         struct sfb_sched_data *q = qdisc_priv(sch);
 611
 612         return q->qdisc;
 613 }
 614
 615 static unsigned long sfb_get(struct Qdisc *sch, u32 classid)
 616 {
 617         return 1;
 618 }
 619
 620 static void sfb_put(struct Qdisc *sch, unsigned long arg)
 621 {
 622 }
 623
 624 static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 625                             struct nlattr **tca, unsigned long *arg)
 626 {
 627         return -ENOSYS;
 628 }
 629
 630 static int sfb_delete(struct Qdisc *sch, unsigned long cl)
 631 {
 632         return -ENOSYS;
 633 }
 634
 635 static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 636 {
 637         if (!walker->stop) {
 638                 if (walker->count >= walker->skip)
 639                         if (walker->fn(sch, 1, walker) < 0) {
 640                                 walker->stop = 1;
 641                                 return;
 642                         }
 643                 walker->count++;
 644         }
 645 }
 646
 647 static struct tcf_proto **sfb_find_tcf(struct Qdisc *sch, unsigned long cl)
 648 {
 649         struct sfb_sched_data *q = qdisc_priv(sch);
 650
 651         if (cl)
 652                 return NULL;
 653         return &q->filter_list;
 654 }
 655
 656 static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
 657                               u32 classid)
 658 {
 659         return 0;
 660 }
 661
 662
 663 static const struct Qdisc_class_ops sfb_class_ops = {
 664         .graft          =       sfb_graft,
 665         .leaf           =       sfb_leaf,
 666         .get            =       sfb_get,
 667         .put            =       sfb_put,
 668         .change         =       sfb_change_class,
 669         .delete         =       sfb_delete,
 670         .walk           =       sfb_walk,
 671         .tcf_chain      =       sfb_find_tcf,
 672         .bind_tcf       =       sfb_bind,
 673         .unbind_tcf     =       sfb_put,
 674         .dump           =       sfb_dump_class,
 675 };
 676
 677 static struct Qdisc_ops sfb_qdisc_ops __read_mostly = {
 678         .id             =       "sfb",
 679         .priv_size      =       sizeof(struct sfb_sched_data),
 680         .cl_ops         =       &sfb_class_ops,
 681         .enqueue        =       sfb_enqueue,
 682         .dequeue        =       sfb_dequeue,
 683         .peek           =       sfb_peek,
 684         .init           =       sfb_init,
 685         .reset          =       sfb_reset,
 686         .destroy        =       sfb_destroy,
 687         .change         =       sfb_change,
 688         .dump           =       sfb_dump,
 689         .dump_stats     =       sfb_dump_stats,
 690         .owner          =       THIS_MODULE,
 691 };
 692
 693 static int __init sfb_module_init(void)
 694 {
 695         return register_qdisc(&sfb_qdisc_ops);
 696 }
 697
 698 static void __exit sfb_module_exit(void)
 699 {
 700         unregister_qdisc(&sfb_qdisc_ops);
 701 }
 702
 703 module_init(sfb_module_init)
 704 module_exit(sfb_module_exit)
 705
 706 MODULE_DESCRIPTION("Stochastic Fair Blue queue discipline");
 707 MODULE_AUTHOR("Juliusz Chroboczek");
 708 MODULE_AUTHOR("Eric Dumazet");
 709 MODULE_LICENSE("GPL");