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/pkt_cls.h>
  29 #include <net/inet_ecn.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" */
  43 struct 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  */
  51 struct sfb_bins {
  52         u32               perturbation; /* jhash perturbation */
  53         struct sfb_bucket bins[SFB_LEVELS][SFB_NUMBUCKETS];
  54 };
  55
  56 struct sfb_sched_data {
  57         struct Qdisc    *qdisc;
  58         struct tcf_proto __rcu *filter_list;
  59         struct tcf_block *block;
  60         unsigned long   rehash_interval;
  61         unsigned long   warmup_time;    /* double buffering warmup time in jiffies */
  62         u32             max;
  63         u32             bin_size;       /* maximum queue length per bin */
  64         u32             increment;      /* d1 */
  65         u32             decrement;      /* d2 */
  66         u32             limit;          /* HARD maximal queue length */
  67         u32             penalty_rate;
  68         u32             penalty_burst;
  69         u32             tokens_avail;
  70         unsigned long   rehash_time;
  71         unsigned long   token_time;
  72
  73         u8              slot;           /* current active bins (0 or 1) */
  74         bool            double_buffering;
  75         struct sfb_bins bins[2];
  76
  77         struct {
  78                 u32     earlydrop;
  79                 u32     penaltydrop;
  80                 u32     bucketdrop;
  81                 u32     queuedrop;
  82                 u32     childdrop;      /* drops in child qdisc */
  83                 u32     marked;         /* ECN mark */
  84         } stats;
  85 };
  86
  87 /*
  88  * Each queued skb might be hashed on one or two bins
  89  * We store in skb_cb the two hash values.
  90  * (A zero value means double buffering was not used)
  91  */
  92 struct sfb_skb_cb {
  93         u32 hashes[2];
  94 };
  95
  96 static inline struct sfb_skb_cb *sfb_skb_cb(const struct sk_buff *skb)
  97 {
  98         qdisc_cb_private_validate(skb, sizeof(struct sfb_skb_cb));
  99         return (struct sfb_skb_cb *)qdisc_skb_cb(skb)->data;
 100 }
 101
 102 /*
 103  * If using 'internal' SFB flow classifier, hash comes from skb rxhash
 104  * If using external classifier, hash comes from the classid.
 105  */
 106 static u32 sfb_hash(const struct sk_buff *skb, u32 slot)
 107 {
 108         return sfb_skb_cb(skb)->hashes[slot];
 109 }
 110
 111 /* Probabilities are coded as Q0.16 fixed-point values,
 112  * with 0xFFFF representing 65535/65536 (almost 1.0)
 113  * Addition and subtraction are saturating in [0, 65535]
 114  */
 115 static u32 prob_plus(u32 p1, u32 p2)
 116 {
 117         u32 res = p1 + p2;
 118
 119         return min_t(u32, res, SFB_MAX_PROB);
 120 }
 121
 122 static u32 prob_minus(u32 p1, u32 p2)
 123 {
 124         return p1 > p2 ? p1 - p2 : 0;
 125 }
 126
 127 static void increment_one_qlen(u32 sfbhash, u32 slot, struct sfb_sched_data *q)
 128 {
 129         int i;
 130         struct sfb_bucket *b = &q->bins[slot].bins[0][0];
 131
 132         for (i = 0; i < SFB_LEVELS; i++) {
 133                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 134
 135                 sfbhash >>= SFB_BUCKET_SHIFT;
 136                 if (b[hash].qlen < 0xFFFF)
 137                         b[hash].qlen++;
 138                 b += SFB_NUMBUCKETS; /* next level */
 139         }
 140 }
 141
 142 static void increment_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
 143 {
 144         u32 sfbhash;
 145
 146         sfbhash = sfb_hash(skb, 0);
 147         if (sfbhash)
 148                 increment_one_qlen(sfbhash, 0, q);
 149
 150         sfbhash = sfb_hash(skb, 1);
 151         if (sfbhash)
 152                 increment_one_qlen(sfbhash, 1, q);
 153 }
 154
 155 static void decrement_one_qlen(u32 sfbhash, u32 slot,
 156                                struct sfb_sched_data *q)
 157 {
 158         int i;
 159         struct sfb_bucket *b = &q->bins[slot].bins[0][0];
 160
 161         for (i = 0; i < SFB_LEVELS; i++) {
 162                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 163
 164                 sfbhash >>= SFB_BUCKET_SHIFT;
 165                 if (b[hash].qlen > 0)
 166                         b[hash].qlen--;
 167                 b += SFB_NUMBUCKETS; /* next level */
 168         }
 169 }
 170
 171 static void decrement_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
 172 {
 173         u32 sfbhash;
 174
 175         sfbhash = sfb_hash(skb, 0);
 176         if (sfbhash)
 177                 decrement_one_qlen(sfbhash, 0, q);
 178
 179         sfbhash = sfb_hash(skb, 1);
 180         if (sfbhash)
 181                 decrement_one_qlen(sfbhash, 1, q);
 182 }
 183
 184 static void decrement_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
 185 {
 186         b->p_mark = prob_minus(b->p_mark, q->decrement);
 187 }
 188
 189 static void increment_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
 190 {
 191         b->p_mark = prob_plus(b->p_mark, q->increment);
 192 }
 193
 194 static void sfb_zero_all_buckets(struct sfb_sched_data *q)
 195 {
 196         memset(&q->bins, 0, sizeof(q->bins));
 197 }
 198
 199 /*
 200  * compute max qlen, max p_mark, and avg p_mark
 201  */
 202 static u32 sfb_compute_qlen(u32 *prob_r, u32 *avgpm_r, const struct sfb_sched_data *q)
 203 {
 204         int i;
 205         u32 qlen = 0, prob = 0, totalpm = 0;
 206         const struct sfb_bucket *b = &q->bins[q->slot].bins[0][0];
 207
 208         for (i = 0; i < SFB_LEVELS * SFB_NUMBUCKETS; i++) {
 209                 if (qlen < b->qlen)
 210                         qlen = b->qlen;
 211                 totalpm += b->p_mark;
 212                 if (prob < b->p_mark)
 213                         prob = b->p_mark;
 214                 b++;
 215         }
 216         *prob_r = prob;
 217         *avgpm_r = totalpm / (SFB_LEVELS * SFB_NUMBUCKETS);
 218         return qlen;
 219 }
 220
 221
 222 static void sfb_init_perturbation(u32 slot, struct sfb_sched_data *q)
 223 {
 224         q->bins[slot].perturbation = prandom_u32();
 225 }
 226
 227 static void sfb_swap_slot(struct sfb_sched_data *q)
 228 {
 229         sfb_init_perturbation(q->slot, q);
 230         q->slot ^= 1;
 231         q->double_buffering = false;
 232 }
 233
 234 /* Non elastic flows are allowed to use part of the bandwidth, expressed
 235  * in "penalty_rate" packets per second, with "penalty_burst" burst
 236  */
 237 static bool sfb_rate_limit(struct sk_buff *skb, struct sfb_sched_data *q)
 238 {
 239         if (q->penalty_rate == 0 || q->penalty_burst == 0)
 240                 return true;
 241
 242         if (q->tokens_avail < 1) {
 243                 unsigned long age = min(10UL * HZ, jiffies - q->token_time);
 244
 245                 q->tokens_avail = (age * q->penalty_rate) / HZ;
 246                 if (q->tokens_avail > q->penalty_burst)
 247                         q->tokens_avail = q->penalty_burst;
 248                 q->token_time = jiffies;
 249                 if (q->tokens_avail < 1)
 250                         return true;
 251         }
 252
 253         q->tokens_avail--;
 254         return false;
 255 }
 256
 257 static bool sfb_classify(struct sk_buff *skb, struct tcf_proto *fl,
 258                          int *qerr, u32 *salt)
 259 {
 260         struct tcf_result res;
 261         int result;
 262
 263         result = tcf_classify(skb, fl, &res, false);
 264         if (result >= 0) {
 265 #ifdef CONFIG_NET_CLS_ACT
 266                 switch (result) {
 267                 case TC_ACT_STOLEN:
 268                 case TC_ACT_QUEUED:
 269                 case TC_ACT_TRAP:
 270                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 271                 case TC_ACT_SHOT:
 272                         return false;
 273                 }
 274 #endif
 275                 *salt = TC_H_MIN(res.classid);
 276                 return true;
 277         }
 278         return false;
 279 }
 280
 281 static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 282                        struct sk_buff **to_free)
 283 {
 284
 285         struct sfb_sched_data *q = qdisc_priv(sch);
 286         struct Qdisc *child = q->qdisc;
 287         struct tcf_proto *fl;
 288         int i;
 289         u32 p_min = ~0;
 290         u32 minqlen = ~0;
 291         u32 r, sfbhash;
 292         u32 slot = q->slot;
 293         int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 294
 295         if (unlikely(sch->q.qlen >= q->limit)) {
 296                 qdisc_qstats_overlimit(sch);
 297                 q->stats.queuedrop++;
 298                 goto drop;
 299         }
 300
 301         if (q->rehash_interval > 0) {
 302                 unsigned long limit = q->rehash_time + q->rehash_interval;
 303
 304                 if (unlikely(time_after(jiffies, limit))) {
 305                         sfb_swap_slot(q);
 306                         q->rehash_time = jiffies;
 307                 } else if (unlikely(!q->double_buffering && q->warmup_time > 0 &&
 308                                     time_after(jiffies, limit - q->warmup_time))) {
 309                         q->double_buffering = true;
 310                 }
 311         }
 312
 313         fl = rcu_dereference_bh(q->filter_list);
 314         if (fl) {
 315                 u32 salt;
 316
 317                 /* If using external classifiers, get result and record it. */
 318                 if (!sfb_classify(skb, fl, &ret, &salt))
 319                         goto other_drop;
 320                 sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
 321         } else {
 322                 sfbhash = skb_get_hash_perturb(skb, q->bins[slot].perturbation);
 323         }
 324
 325
 326         if (!sfbhash)
 327                 sfbhash = 1;
 328         sfb_skb_cb(skb)->hashes[slot] = sfbhash;
 329
 330         for (i = 0; i < SFB_LEVELS; i++) {
 331                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 332                 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
 333
 334                 sfbhash >>= SFB_BUCKET_SHIFT;
 335                 if (b->qlen == 0)
 336                         decrement_prob(b, q);
 337                 else if (b->qlen >= q->bin_size)
 338                         increment_prob(b, q);
 339                 if (minqlen > b->qlen)
 340                         minqlen = b->qlen;
 341                 if (p_min > b->p_mark)
 342                         p_min = b->p_mark;
 343         }
 344
 345         slot ^= 1;
 346         sfb_skb_cb(skb)->hashes[slot] = 0;
 347
 348         if (unlikely(minqlen >= q->max)) {
 349                 qdisc_qstats_overlimit(sch);
 350                 q->stats.bucketdrop++;
 351                 goto drop;
 352         }
 353
 354         if (unlikely(p_min >= SFB_MAX_PROB)) {
 355                 /* Inelastic flow */
 356                 if (q->double_buffering) {
 357                         sfbhash = skb_get_hash_perturb(skb,
 358                             q->bins[slot].perturbation);
 359                         if (!sfbhash)
 360                                 sfbhash = 1;
 361                         sfb_skb_cb(skb)->hashes[slot] = sfbhash;
 362
 363                         for (i = 0; i < SFB_LEVELS; i++) {
 364                                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 365                                 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
 366
 367                                 sfbhash >>= SFB_BUCKET_SHIFT;
 368                                 if (b->qlen == 0)
 369                                         decrement_prob(b, q);
 370                                 else if (b->qlen >= q->bin_size)
 371                                         increment_prob(b, q);
 372                         }
 373                 }
 374                 if (sfb_rate_limit(skb, q)) {
 375                         qdisc_qstats_overlimit(sch);
 376                         q->stats.penaltydrop++;
 377                         goto drop;
 378                 }
 379                 goto enqueue;
 380         }
 381
 382         r = prandom_u32() & SFB_MAX_PROB;
 383
 384         if (unlikely(r < p_min)) {
 385                 if (unlikely(p_min > SFB_MAX_PROB / 2)) {
 386                         /* If we're marking that many packets, then either
 387                          * this flow is unresponsive, or we're badly congested.
 388                          * In either case, we want to start dropping packets.
 389                          */
 390                         if (r < (p_min - SFB_MAX_PROB / 2) * 2) {
 391                                 q->stats.earlydrop++;
 392                                 goto drop;
 393                         }
 394                 }
 395                 if (INET_ECN_set_ce(skb)) {
 396                         q->stats.marked++;
 397                 } else {
 398                         q->stats.earlydrop++;
 399                         goto drop;
 400                 }
 401         }
 402
 403 enqueue:
 404         ret = qdisc_enqueue(skb, child, to_free);
 405         if (likely(ret == NET_XMIT_SUCCESS)) {
 406                 qdisc_qstats_backlog_inc(sch, skb);
 407                 sch->q.qlen++;
 408                 increment_qlen(skb, q);
 409         } else if (net_xmit_drop_count(ret)) {
 410                 q->stats.childdrop++;
 411                 qdisc_qstats_drop(sch);
 412         }
 413         return ret;
 414
 415 drop:
 416         qdisc_drop(skb, sch, to_free);
 417         return NET_XMIT_CN;
 418 other_drop:
 419         if (ret & __NET_XMIT_BYPASS)
 420                 qdisc_qstats_drop(sch);
 421         kfree_skb(skb);
 422         return ret;
 423 }
 424
 425 static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
 426 {
 427         struct sfb_sched_data *q = qdisc_priv(sch);
 428         struct Qdisc *child = q->qdisc;
 429         struct sk_buff *skb;
 430
 431         skb = child->dequeue(q->qdisc);
 432
 433         if (skb) {
 434                 qdisc_bstats_update(sch, skb);
 435                 qdisc_qstats_backlog_dec(sch, skb);
 436                 sch->q.qlen--;
 437                 decrement_qlen(skb, q);
 438         }
 439
 440         return skb;
 441 }
 442
 443 static struct sk_buff *sfb_peek(struct Qdisc *sch)
 444 {
 445         struct sfb_sched_data *q = qdisc_priv(sch);
 446         struct Qdisc *child = q->qdisc;
 447
 448         return child->ops->peek(child);
 449 }
 450
 451 /* No sfb_drop -- impossible since the child doesn't return the dropped skb. */
 452
 453 static void sfb_reset(struct Qdisc *sch)
 454 {
 455         struct sfb_sched_data *q = qdisc_priv(sch);
 456
 457         qdisc_reset(q->qdisc);
 458         sch->qstats.backlog = 0;
 459         sch->q.qlen = 0;
 460         q->slot = 0;
 461         q->double_buffering = false;
 462         sfb_zero_all_buckets(q);
 463         sfb_init_perturbation(0, q);
 464 }
 465
 466 static void sfb_destroy(struct Qdisc *sch)
 467 {
 468         struct sfb_sched_data *q = qdisc_priv(sch);
 469
 470         tcf_block_put(q->block);
 471         qdisc_destroy(q->qdisc);
 472 }
 473
 474 static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
 475         [TCA_SFB_PARMS] = { .len = sizeof(struct tc_sfb_qopt) },
 476 };
 477
 478 static const struct tc_sfb_qopt sfb_default_ops = {
 479         .rehash_interval = 600 * MSEC_PER_SEC,
 480         .warmup_time = 60 * MSEC_PER_SEC,
 481         .limit = 0,
 482         .max = 25,
 483         .bin_size = 20,
 484         .increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
 485         .decrement = (SFB_MAX_PROB + 3000) / 6000,
 486         .penalty_rate = 10,
 487         .penalty_burst = 20,
 488 };
 489
 490 static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
 491 {
 492         struct sfb_sched_data *q = qdisc_priv(sch);
 493         struct Qdisc *child;
 494         struct nlattr *tb[TCA_SFB_MAX + 1];
 495         const struct tc_sfb_qopt *ctl = &sfb_default_ops;
 496         u32 limit;
 497         int err;
 498
 499         if (opt) {
 500                 err = nla_parse_nested(tb, TCA_SFB_MAX, opt, sfb_policy, NULL);
 501                 if (err < 0)
 502                         return -EINVAL;
 503
 504                 if (tb[TCA_SFB_PARMS] == NULL)
 505                         return -EINVAL;
 506
 507                 ctl = nla_data(tb[TCA_SFB_PARMS]);
 508         }
 509
 510         limit = ctl->limit;
 511         if (limit == 0)
 512                 limit = qdisc_dev(sch)->tx_queue_len;
 513
 514         child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
 515         if (IS_ERR(child))
 516                 return PTR_ERR(child);
 517
 518         if (child != &noop_qdisc)
 519                 qdisc_hash_add(child, true);
 520         sch_tree_lock(sch);
 521
 522         qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
 523                                   q->qdisc->qstats.backlog);
 524         qdisc_destroy(q->qdisc);
 525         q->qdisc = child;
 526
 527         q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
 528         q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
 529         q->rehash_time = jiffies;
 530         q->limit = limit;
 531         q->increment = ctl->increment;
 532         q->decrement = ctl->decrement;
 533         q->max = ctl->max;
 534         q->bin_size = ctl->bin_size;
 535         q->penalty_rate = ctl->penalty_rate;
 536         q->penalty_burst = ctl->penalty_burst;
 537         q->tokens_avail = ctl->penalty_burst;
 538         q->token_time = jiffies;
 539
 540         q->slot = 0;
 541         q->double_buffering = false;
 542         sfb_zero_all_buckets(q);
 543         sfb_init_perturbation(0, q);
 544         sfb_init_perturbation(1, q);
 545
 546         sch_tree_unlock(sch);
 547
 548         return 0;
 549 }
 550
 551 static int sfb_init(struct Qdisc *sch, struct nlattr *opt)
 552 {
 553         struct sfb_sched_data *q = qdisc_priv(sch);
 554         int err;
 555
 556         err = tcf_block_get(&q->block, &q->filter_list);
 557         if (err)
 558                 return err;
 559
 560         q->qdisc = &noop_qdisc;
 561         return sfb_change(sch, opt);
 562 }
 563
 564 static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
 565 {
 566         struct sfb_sched_data *q = qdisc_priv(sch);
 567         struct nlattr *opts;
 568         struct tc_sfb_qopt opt = {
 569                 .rehash_interval = jiffies_to_msecs(q->rehash_interval),
 570                 .warmup_time = jiffies_to_msecs(q->warmup_time),
 571                 .limit = q->limit,
 572                 .max = q->max,
 573                 .bin_size = q->bin_size,
 574                 .increment = q->increment,
 575                 .decrement = q->decrement,
 576                 .penalty_rate = q->penalty_rate,
 577                 .penalty_burst = q->penalty_burst,
 578         };
 579
 580         sch->qstats.backlog = q->qdisc->qstats.backlog;
 581         opts = nla_nest_start(skb, TCA_OPTIONS);
 582         if (opts == NULL)
 583                 goto nla_put_failure;
 584         if (nla_put(skb, TCA_SFB_PARMS, sizeof(opt), &opt))
 585                 goto nla_put_failure;
 586         return nla_nest_end(skb, opts);
 587
 588 nla_put_failure:
 589         nla_nest_cancel(skb, opts);
 590         return -EMSGSIZE;
 591 }
 592
 593 static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 594 {
 595         struct sfb_sched_data *q = qdisc_priv(sch);
 596         struct tc_sfb_xstats st = {
 597                 .earlydrop = q->stats.earlydrop,
 598                 .penaltydrop = q->stats.penaltydrop,
 599                 .bucketdrop = q->stats.bucketdrop,
 600                 .queuedrop = q->stats.queuedrop,
 601                 .childdrop = q->stats.childdrop,
 602                 .marked = q->stats.marked,
 603         };
 604
 605         st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);
 606
 607         return gnet_stats_copy_app(d, &st, sizeof(st));
 608 }
 609
 610 static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
 611                           struct sk_buff *skb, struct tcmsg *tcm)
 612 {
 613         return -ENOSYS;
 614 }
 615
 616 static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 617                      struct Qdisc **old)
 618 {
 619         struct sfb_sched_data *q = qdisc_priv(sch);
 620
 621         if (new == NULL)
 622                 new = &noop_qdisc;
 623
 624         *old = qdisc_replace(sch, new, &q->qdisc);
 625         return 0;
 626 }
 627
 628 static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
 629 {
 630         struct sfb_sched_data *q = qdisc_priv(sch);
 631
 632         return q->qdisc;
 633 }
 634
 635 static unsigned long sfb_find(struct Qdisc *sch, u32 classid)
 636 {
 637         return 1;
 638 }
 639
 640 static void sfb_unbind(struct Qdisc *sch, unsigned long arg)
 641 {
 642 }
 643
 644 static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 645                             struct nlattr **tca, unsigned long *arg)
 646 {
 647         return -ENOSYS;
 648 }
 649
 650 static int sfb_delete(struct Qdisc *sch, unsigned long cl)
 651 {
 652         return -ENOSYS;
 653 }
 654
 655 static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 656 {
 657         if (!walker->stop) {
 658                 if (walker->count >= walker->skip)
 659                         if (walker->fn(sch, 1, walker) < 0) {
 660                                 walker->stop = 1;
 661                                 return;
 662                         }
 663                 walker->count++;
 664         }
 665 }
 666
 667 static struct tcf_block *sfb_tcf_block(struct Qdisc *sch, unsigned long cl)
 668 {
 669         struct sfb_sched_data *q = qdisc_priv(sch);
 670
 671         if (cl)
 672                 return NULL;
 673         return q->block;
 674 }
 675
 676 static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
 677                               u32 classid)
 678 {
 679         return 0;
 680 }
 681
 682
 683 static const struct Qdisc_class_ops sfb_class_ops = {
 684         .graft          =       sfb_graft,
 685         .leaf           =       sfb_leaf,
 686         .find           =       sfb_find,
 687         .change         =       sfb_change_class,
 688         .delete         =       sfb_delete,
 689         .walk           =       sfb_walk,
 690         .tcf_block      =       sfb_tcf_block,
 691         .bind_tcf       =       sfb_bind,
 692         .unbind_tcf     =       sfb_unbind,
 693         .dump           =       sfb_dump_class,
 694 };
 695
 696 static 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
 712 static int __init sfb_module_init(void)
 713 {
 714         return register_qdisc(&sfb_qdisc_ops);
 715 }
 716
 717 static void __exit sfb_module_exit(void)
 718 {
 719         unregister_qdisc(&sfb_qdisc_ops);
 720 }
 721
 722 module_init(sfb_module_init)
 723 module_exit(sfb_module_exit)
 724
 725 MODULE_DESCRIPTION("Stochastic Fair Blue queue discipline");
 726 MODULE_AUTHOR("Juliusz Chroboczek");
 727 MODULE_AUTHOR("Eric Dumazet");
 728 MODULE_LICENSE("GPL");