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         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 = net_random();
 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 sfb_sched_data *q,
 256                          int *qerr, u32 *salt)
 257 {
 258         struct tcf_result res;
 259         int result;
 260
 261         result = tc_classify(skb, q->filter_list, &res);
 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 {
 280
 281         struct sfb_sched_data *q = qdisc_priv(sch);
 282         struct Qdisc *child = q->qdisc;
 283         int i;
 284         u32 p_min = ~0;
 285         u32 minqlen = ~0;
 286         u32 r, slot, salt, sfbhash;
 287         int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 288
 289         if (q->rehash_interval > 0) {
 290                 unsigned long limit = q->rehash_time + q->rehash_interval;
 291
 292                 if (unlikely(time_after(jiffies, limit))) {
 293                         sfb_swap_slot(q);
 294                         q->rehash_time = jiffies;
 295                 } else if (unlikely(!q->double_buffering && q->warmup_time > 0 &&
 296                                     time_after(jiffies, limit - q->warmup_time))) {
 297                         q->double_buffering = true;
 298                 }
 299         }
 300
 301         if (q->filter_list) {
 302                 /* If using external classifiers, get result and record it. */
 303                 if (!sfb_classify(skb, q, &ret, &salt))
 304                         goto other_drop;
 305         } else {
 306                 salt = skb_get_rxhash(skb);
 307         }
 308
 309         slot = q->slot;
 310
 311         sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
 312         if (!sfbhash)
 313                 sfbhash = 1;
 314         sfb_skb_cb(skb)->hashes[slot] = sfbhash;
 315
 316         for (i = 0; i < SFB_LEVELS; i++) {
 317                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 318                 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
 319
 320                 sfbhash >>= SFB_BUCKET_SHIFT;
 321                 if (b->qlen == 0)
 322                         decrement_prob(b, q);
 323                 else if (b->qlen >= q->bin_size)
 324                         increment_prob(b, q);
 325                 if (minqlen > b->qlen)
 326                         minqlen = b->qlen;
 327                 if (p_min > b->p_mark)
 328                         p_min = b->p_mark;
 329         }
 330
 331         slot ^= 1;
 332         sfb_skb_cb(skb)->hashes[slot] = 0;
 333
 334         if (unlikely(minqlen >= q->max || sch->q.qlen >= q->limit)) {
 335                 sch->qstats.overlimits++;
 336                 if (minqlen >= q->max)
 337                         q->stats.bucketdrop++;
 338                 else
 339                         q->stats.queuedrop++;
 340                 goto drop;
 341         }
 342
 343         if (unlikely(p_min >= SFB_MAX_PROB)) {
 344                 /* Inelastic flow */
 345                 if (q->double_buffering) {
 346                         sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
 347                         if (!sfbhash)
 348                                 sfbhash = 1;
 349                         sfb_skb_cb(skb)->hashes[slot] = sfbhash;
 350
 351                         for (i = 0; i < SFB_LEVELS; i++) {
 352                                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 353                                 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
 354
 355                                 sfbhash >>= SFB_BUCKET_SHIFT;
 356                                 if (b->qlen == 0)
 357                                         decrement_prob(b, q);
 358                                 else if (b->qlen >= q->bin_size)
 359                                         increment_prob(b, q);
 360                         }
 361                 }
 362                 if (sfb_rate_limit(skb, q)) {
 363                         sch->qstats.overlimits++;
 364                         q->stats.penaltydrop++;
 365                         goto drop;
 366                 }
 367                 goto enqueue;
 368         }
 369
 370         r = net_random() & SFB_MAX_PROB;
 371
 372         if (unlikely(r < p_min)) {
 373                 if (unlikely(p_min > SFB_MAX_PROB / 2)) {
 374                         /* If we're marking that many packets, then either
 375                          * this flow is unresponsive, or we're badly congested.
 376                          * In either case, we want to start dropping packets.
 377                          */
 378                         if (r < (p_min - SFB_MAX_PROB / 2) * 2) {
 379                                 q->stats.earlydrop++;
 380                                 goto drop;
 381                         }
 382                 }
 383                 if (INET_ECN_set_ce(skb)) {
 384                         q->stats.marked++;
 385                 } else {
 386                         q->stats.earlydrop++;
 387                         goto drop;
 388                 }
 389         }
 390
 391 enqueue:
 392         ret = qdisc_enqueue(skb, child);
 393         if (likely(ret == NET_XMIT_SUCCESS)) {
 394                 sch->q.qlen++;
 395                 increment_qlen(skb, q);
 396         } else if (net_xmit_drop_count(ret)) {
 397                 q->stats.childdrop++;
 398                 sch->qstats.drops++;
 399         }
 400         return ret;
 401
 402 drop:
 403         qdisc_drop(skb, sch);
 404         return NET_XMIT_CN;
 405 other_drop:
 406         if (ret & __NET_XMIT_BYPASS)
 407                 sch->qstats.drops++;
 408         kfree_skb(skb);
 409         return ret;
 410 }
 411
 412 static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
 413 {
 414         struct sfb_sched_data *q = qdisc_priv(sch);
 415         struct Qdisc *child = q->qdisc;
 416         struct sk_buff *skb;
 417
 418         skb = child->dequeue(q->qdisc);
 419
 420         if (skb) {
 421                 qdisc_bstats_update(sch, skb);
 422                 sch->q.qlen--;
 423                 decrement_qlen(skb, q);
 424         }
 425
 426         return skb;
 427 }
 428
 429 static struct sk_buff *sfb_peek(struct Qdisc *sch)
 430 {
 431         struct sfb_sched_data *q = qdisc_priv(sch);
 432         struct Qdisc *child = q->qdisc;
 433
 434         return child->ops->peek(child);
 435 }
 436
 437 /* No sfb_drop -- impossible since the child doesn't return the dropped skb. */
 438
 439 static void sfb_reset(struct Qdisc *sch)
 440 {
 441         struct sfb_sched_data *q = qdisc_priv(sch);
 442
 443         qdisc_reset(q->qdisc);
 444         sch->q.qlen = 0;
 445         q->slot = 0;
 446         q->double_buffering = false;
 447         sfb_zero_all_buckets(q);
 448         sfb_init_perturbation(0, q);
 449 }
 450
 451 static void sfb_destroy(struct Qdisc *sch)
 452 {
 453         struct sfb_sched_data *q = qdisc_priv(sch);
 454
 455         tcf_destroy_chain(&q->filter_list);
 456         qdisc_destroy(q->qdisc);
 457 }
 458
 459 static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
 460         [TCA_SFB_PARMS] = { .len = sizeof(struct tc_sfb_qopt) },
 461 };
 462
 463 static const struct tc_sfb_qopt sfb_default_ops = {
 464         .rehash_interval = 600 * MSEC_PER_SEC,
 465         .warmup_time = 60 * MSEC_PER_SEC,
 466         .limit = 0,
 467         .max = 25,
 468         .bin_size = 20,
 469         .increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
 470         .decrement = (SFB_MAX_PROB + 3000) / 6000,
 471         .penalty_rate = 10,
 472         .penalty_burst = 20,
 473 };
 474
 475 static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
 476 {
 477         struct sfb_sched_data *q = qdisc_priv(sch);
 478         struct Qdisc *child;
 479         struct nlattr *tb[TCA_SFB_MAX + 1];
 480         const struct tc_sfb_qopt *ctl = &sfb_default_ops;
 481         u32 limit;
 482         int err;
 483
 484         if (opt) {
 485                 err = nla_parse_nested(tb, TCA_SFB_MAX, opt, sfb_policy);
 486                 if (err < 0)
 487                         return -EINVAL;
 488
 489                 if (tb[TCA_SFB_PARMS] == NULL)
 490                         return -EINVAL;
 491
 492                 ctl = nla_data(tb[TCA_SFB_PARMS]);
 493         }
 494
 495         limit = ctl->limit;
 496         if (limit == 0)
 497                 limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
 498
 499         child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
 500         if (IS_ERR(child))
 501                 return PTR_ERR(child);
 502
 503         sch_tree_lock(sch);
 504
 505         qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
 506         qdisc_destroy(q->qdisc);
 507         q->qdisc = child;
 508
 509         q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
 510         q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
 511         q->rehash_time = jiffies;
 512         q->limit = limit;
 513         q->increment = ctl->increment;
 514         q->decrement = ctl->decrement;
 515         q->max = ctl->max;
 516         q->bin_size = ctl->bin_size;
 517         q->penalty_rate = ctl->penalty_rate;
 518         q->penalty_burst = ctl->penalty_burst;
 519         q->tokens_avail = ctl->penalty_burst;
 520         q->token_time = jiffies;
 521
 522         q->slot = 0;
 523         q->double_buffering = false;
 524         sfb_zero_all_buckets(q);
 525         sfb_init_perturbation(0, q);
 526         sfb_init_perturbation(1, q);
 527
 528         sch_tree_unlock(sch);
 529
 530         return 0;
 531 }
 532
 533 static int sfb_init(struct Qdisc *sch, struct nlattr *opt)
 534 {
 535         struct sfb_sched_data *q = qdisc_priv(sch);
 536
 537         q->qdisc = &noop_qdisc;
 538         return sfb_change(sch, opt);
 539 }
 540
 541 static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
 542 {
 543         struct sfb_sched_data *q = qdisc_priv(sch);
 544         struct nlattr *opts;
 545         struct tc_sfb_qopt opt = {
 546                 .rehash_interval = jiffies_to_msecs(q->rehash_interval),
 547                 .warmup_time = jiffies_to_msecs(q->warmup_time),
 548                 .limit = q->limit,
 549                 .max = q->max,
 550                 .bin_size = q->bin_size,
 551                 .increment = q->increment,
 552                 .decrement = q->decrement,
 553                 .penalty_rate = q->penalty_rate,
 554                 .penalty_burst = q->penalty_burst,
 555         };
 556
 557         sch->qstats.backlog = q->qdisc->qstats.backlog;
 558         opts = nla_nest_start(skb, TCA_OPTIONS);
 559         NLA_PUT(skb, TCA_SFB_PARMS, sizeof(opt), &opt);
 560         return nla_nest_end(skb, opts);
 561
 562 nla_put_failure:
 563         nla_nest_cancel(skb, opts);
 564         return -EMSGSIZE;
 565 }
 566
 567 static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 568 {
 569         struct sfb_sched_data *q = qdisc_priv(sch);
 570         struct tc_sfb_xstats st = {
 571                 .earlydrop = q->stats.earlydrop,
 572                 .penaltydrop = q->stats.penaltydrop,
 573                 .bucketdrop = q->stats.bucketdrop,
 574                 .queuedrop = q->stats.queuedrop,
 575                 .childdrop = q->stats.childdrop,
 576                 .marked = q->stats.marked,
 577         };
 578
 579         st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);
 580
 581         return gnet_stats_copy_app(d, &st, sizeof(st));
 582 }
 583
 584 static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
 585                           struct sk_buff *skb, struct tcmsg *tcm)
 586 {
 587         return -ENOSYS;
 588 }
 589
 590 static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 591                      struct Qdisc **old)
 592 {
 593         struct sfb_sched_data *q = qdisc_priv(sch);
 594
 595         if (new == NULL)
 596                 new = &noop_qdisc;
 597
 598         sch_tree_lock(sch);
 599         *old = q->qdisc;
 600         q->qdisc = new;
 601         qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
 602         qdisc_reset(*old);
 603         sch_tree_unlock(sch);
 604         return 0;
 605 }
 606
 607 static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
 608 {
 609         struct sfb_sched_data *q = qdisc_priv(sch);
 610
 611         return q->qdisc;
 612 }
 613
 614 static unsigned long sfb_get(struct Qdisc *sch, u32 classid)
 615 {
 616         return 1;
 617 }
 618
 619 static void sfb_put(struct Qdisc *sch, unsigned long arg)
 620 {
 621 }
 622
 623 static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 624                             struct nlattr **tca, unsigned long *arg)
 625 {
 626         return -ENOSYS;
 627 }
 628
 629 static int sfb_delete(struct Qdisc *sch, unsigned long cl)
 630 {
 631         return -ENOSYS;
 632 }
 633
 634 static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 635 {
 636         if (!walker->stop) {
 637                 if (walker->count >= walker->skip)
 638                         if (walker->fn(sch, 1, walker) < 0) {
 639                                 walker->stop = 1;
 640                                 return;
 641                         }
 642                 walker->count++;
 643         }
 644 }
 645
 646 static struct tcf_proto **sfb_find_tcf(struct Qdisc *sch, unsigned long cl)
 647 {
 648         struct sfb_sched_data *q = qdisc_priv(sch);
 649
 650         if (cl)
 651                 return NULL;
 652         return &q->filter_list;
 653 }
 654
 655 static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
 656                               u32 classid)
 657 {
 658         return 0;
 659 }
 660
 661
 662 static const struct Qdisc_class_ops sfb_class_ops = {
 663         .graft          =       sfb_graft,
 664         .leaf           =       sfb_leaf,
 665         .get            =       sfb_get,
 666         .put            =       sfb_put,
 667         .change         =       sfb_change_class,
 668         .delete         =       sfb_delete,
 669         .walk           =       sfb_walk,
 670         .tcf_chain      =       sfb_find_tcf,
 671         .bind_tcf       =       sfb_bind,
 672         .unbind_tcf     =       sfb_put,
 673         .dump           =       sfb_dump_class,
 674 };
 675
 676 static struct Qdisc_ops sfb_qdisc_ops __read_mostly = {
 677         .id             =       "sfb",
 678         .priv_size      =       sizeof(struct sfb_sched_data),
 679         .cl_ops         =       &sfb_class_ops,
 680         .enqueue        =       sfb_enqueue,
 681         .dequeue        =       sfb_dequeue,
 682         .peek           =       sfb_peek,
 683         .init           =       sfb_init,
 684         .reset          =       sfb_reset,
 685         .destroy        =       sfb_destroy,
 686         .change         =       sfb_change,
 687         .dump           =       sfb_dump,
 688         .dump_stats     =       sfb_dump_stats,
 689         .owner          =       THIS_MODULE,
 690 };
 691
 692 static int __init sfb_module_init(void)
 693 {
 694         return register_qdisc(&sfb_qdisc_ops);
 695 }
 696
 697 static void __exit sfb_module_exit(void)
 698 {
 699         unregister_qdisc(&sfb_qdisc_ops);
 700 }
 701
 702 module_init(sfb_module_init)
 703 module_exit(sfb_module_exit)
 704
 705 MODULE_DESCRIPTION("Stochastic Fair Blue queue discipline");
 706 MODULE_AUTHOR("Juliusz Chroboczek");
 707 MODULE_AUTHOR("Eric Dumazet");
 708 MODULE_LICENSE("GPL");