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 __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                 sch->q.qlen++;
 404                 increment_qlen(skb, q);
 405         } else if (net_xmit_drop_count(ret)) {
 406                 q->stats.childdrop++;
 407                 qdisc_qstats_drop(sch);
 408         }
 409         return ret;
 410
 411 drop:
 412         qdisc_drop(skb, sch, to_free);
 413         return NET_XMIT_CN;
 414 other_drop:
 415         if (ret & __NET_XMIT_BYPASS)
 416                 qdisc_qstats_drop(sch);
 417         kfree_skb(skb);
 418         return ret;
 419 }
 420
 421 static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
 422 {
 423         struct sfb_sched_data *q = qdisc_priv(sch);
 424         struct Qdisc *child = q->qdisc;
 425         struct sk_buff *skb;
 426
 427         skb = child->dequeue(q->qdisc);
 428
 429         if (skb) {
 430                 qdisc_bstats_update(sch, skb);
 431                 sch->q.qlen--;
 432                 decrement_qlen(skb, q);
 433         }
 434
 435         return skb;
 436 }
 437
 438 static struct sk_buff *sfb_peek(struct Qdisc *sch)
 439 {
 440         struct sfb_sched_data *q = qdisc_priv(sch);
 441         struct Qdisc *child = q->qdisc;
 442
 443         return child->ops->peek(child);
 444 }
 445
 446 /* No sfb_drop -- impossible since the child doesn't return the dropped skb. */
 447
 448 static void sfb_reset(struct Qdisc *sch)
 449 {
 450         struct sfb_sched_data *q = qdisc_priv(sch);
 451
 452         qdisc_reset(q->qdisc);
 453         sch->q.qlen = 0;
 454         q->slot = 0;
 455         q->double_buffering = false;
 456         sfb_zero_all_buckets(q);
 457         sfb_init_perturbation(0, q);
 458 }
 459
 460 static void sfb_destroy(struct Qdisc *sch)
 461 {
 462         struct sfb_sched_data *q = qdisc_priv(sch);
 463
 464         tcf_destroy_chain(&q->filter_list);
 465         qdisc_destroy(q->qdisc);
 466 }
 467
 468 static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
 469         [TCA_SFB_PARMS] = { .len = sizeof(struct tc_sfb_qopt) },
 470 };
 471
 472 static const struct tc_sfb_qopt sfb_default_ops = {
 473         .rehash_interval = 600 * MSEC_PER_SEC,
 474         .warmup_time = 60 * MSEC_PER_SEC,
 475         .limit = 0,
 476         .max = 25,
 477         .bin_size = 20,
 478         .increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
 479         .decrement = (SFB_MAX_PROB + 3000) / 6000,
 480         .penalty_rate = 10,
 481         .penalty_burst = 20,
 482 };
 483
 484 static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
 485 {
 486         struct sfb_sched_data *q = qdisc_priv(sch);
 487         struct Qdisc *child;
 488         struct nlattr *tb[TCA_SFB_MAX + 1];
 489         const struct tc_sfb_qopt *ctl = &sfb_default_ops;
 490         u32 limit;
 491         int err;
 492
 493         if (opt) {
 494                 err = nla_parse_nested(tb, TCA_SFB_MAX, opt, sfb_policy);
 495                 if (err < 0)
 496                         return -EINVAL;
 497
 498                 if (tb[TCA_SFB_PARMS] == NULL)
 499                         return -EINVAL;
 500
 501                 ctl = nla_data(tb[TCA_SFB_PARMS]);
 502         }
 503
 504         limit = ctl->limit;
 505         if (limit == 0)
 506                 limit = qdisc_dev(sch)->tx_queue_len;
 507
 508         child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
 509         if (IS_ERR(child))
 510                 return PTR_ERR(child);
 511
 512         sch_tree_lock(sch);
 513
 514         qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
 515                                   q->qdisc->qstats.backlog);
 516         qdisc_destroy(q->qdisc);
 517         q->qdisc = child;
 518
 519         q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
 520         q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
 521         q->rehash_time = jiffies;
 522         q->limit = limit;
 523         q->increment = ctl->increment;
 524         q->decrement = ctl->decrement;
 525         q->max = ctl->max;
 526         q->bin_size = ctl->bin_size;
 527         q->penalty_rate = ctl->penalty_rate;
 528         q->penalty_burst = ctl->penalty_burst;
 529         q->tokens_avail = ctl->penalty_burst;
 530         q->token_time = jiffies;
 531
 532         q->slot = 0;
 533         q->double_buffering = false;
 534         sfb_zero_all_buckets(q);
 535         sfb_init_perturbation(0, q);
 536         sfb_init_perturbation(1, q);
 537
 538         sch_tree_unlock(sch);
 539
 540         return 0;
 541 }
 542
 543 static int sfb_init(struct Qdisc *sch, struct nlattr *opt)
 544 {
 545         struct sfb_sched_data *q = qdisc_priv(sch);
 546
 547         q->qdisc = &noop_qdisc;
 548         return sfb_change(sch, opt);
 549 }
 550
 551 static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
 552 {
 553         struct sfb_sched_data *q = qdisc_priv(sch);
 554         struct nlattr *opts;
 555         struct tc_sfb_qopt opt = {
 556                 .rehash_interval = jiffies_to_msecs(q->rehash_interval),
 557                 .warmup_time = jiffies_to_msecs(q->warmup_time),
 558                 .limit = q->limit,
 559                 .max = q->max,
 560                 .bin_size = q->bin_size,
 561                 .increment = q->increment,
 562                 .decrement = q->decrement,
 563                 .penalty_rate = q->penalty_rate,
 564                 .penalty_burst = q->penalty_burst,
 565         };
 566
 567         sch->qstats.backlog = q->qdisc->qstats.backlog;
 568         opts = nla_nest_start(skb, TCA_OPTIONS);
 569         if (opts == NULL)
 570                 goto nla_put_failure;
 571         if (nla_put(skb, TCA_SFB_PARMS, sizeof(opt), &opt))
 572                 goto nla_put_failure;
 573         return nla_nest_end(skb, opts);
 574
 575 nla_put_failure:
 576         nla_nest_cancel(skb, opts);
 577         return -EMSGSIZE;
 578 }
 579
 580 static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 581 {
 582         struct sfb_sched_data *q = qdisc_priv(sch);
 583         struct tc_sfb_xstats st = {
 584                 .earlydrop = q->stats.earlydrop,
 585                 .penaltydrop = q->stats.penaltydrop,
 586                 .bucketdrop = q->stats.bucketdrop,
 587                 .queuedrop = q->stats.queuedrop,
 588                 .childdrop = q->stats.childdrop,
 589                 .marked = q->stats.marked,
 590         };
 591
 592         st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);
 593
 594         return gnet_stats_copy_app(d, &st, sizeof(st));
 595 }
 596
 597 static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
 598                           struct sk_buff *skb, struct tcmsg *tcm)
 599 {
 600         return -ENOSYS;
 601 }
 602
 603 static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 604                      struct Qdisc **old)
 605 {
 606         struct sfb_sched_data *q = qdisc_priv(sch);
 607
 608         if (new == NULL)
 609                 new = &noop_qdisc;
 610
 611         *old = qdisc_replace(sch, new, &q->qdisc);
 612         return 0;
 613 }
 614
 615 static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
 616 {
 617         struct sfb_sched_data *q = qdisc_priv(sch);
 618
 619         return q->qdisc;
 620 }
 621
 622 static unsigned long sfb_get(struct Qdisc *sch, u32 classid)
 623 {
 624         return 1;
 625 }
 626
 627 static void sfb_put(struct Qdisc *sch, unsigned long arg)
 628 {
 629 }
 630
 631 static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 632                             struct nlattr **tca, unsigned long *arg)
 633 {
 634         return -ENOSYS;
 635 }
 636
 637 static int sfb_delete(struct Qdisc *sch, unsigned long cl)
 638 {
 639         return -ENOSYS;
 640 }
 641
 642 static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 643 {
 644         if (!walker->stop) {
 645                 if (walker->count >= walker->skip)
 646                         if (walker->fn(sch, 1, walker) < 0) {
 647                                 walker->stop = 1;
 648                                 return;
 649                         }
 650                 walker->count++;
 651         }
 652 }
 653
 654 static struct tcf_proto __rcu **sfb_find_tcf(struct Qdisc *sch,
 655                                              unsigned long cl)
 656 {
 657         struct sfb_sched_data *q = qdisc_priv(sch);
 658
 659         if (cl)
 660                 return NULL;
 661         return &q->filter_list;
 662 }
 663
 664 static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
 665                               u32 classid)
 666 {
 667         return 0;
 668 }
 669
 670
 671 static const struct Qdisc_class_ops sfb_class_ops = {
 672         .graft          =       sfb_graft,
 673         .leaf           =       sfb_leaf,
 674         .get            =       sfb_get,
 675         .put            =       sfb_put,
 676         .change         =       sfb_change_class,
 677         .delete         =       sfb_delete,
 678         .walk           =       sfb_walk,
 679         .tcf_chain      =       sfb_find_tcf,
 680         .bind_tcf       =       sfb_bind,
 681         .unbind_tcf     =       sfb_put,
 682         .dump           =       sfb_dump_class,
 683 };
 684
 685 static struct Qdisc_ops sfb_qdisc_ops __read_mostly = {
 686         .id             =       "sfb",
 687         .priv_size      =       sizeof(struct sfb_sched_data),
 688         .cl_ops         =       &sfb_class_ops,
 689         .enqueue        =       sfb_enqueue,
 690         .dequeue        =       sfb_dequeue,
 691         .peek           =       sfb_peek,
 692         .init           =       sfb_init,
 693         .reset          =       sfb_reset,
 694         .destroy        =       sfb_destroy,
 695         .change         =       sfb_change,
 696         .dump           =       sfb_dump,
 697         .dump_stats     =       sfb_dump_stats,
 698         .owner          =       THIS_MODULE,
 699 };
 700
 701 static int __init sfb_module_init(void)
 702 {
 703         return register_qdisc(&sfb_qdisc_ops);
 704 }
 705
 706 static void __exit sfb_module_exit(void)
 707 {
 708         unregister_qdisc(&sfb_qdisc_ops);
 709 }
 710
 711 module_init(sfb_module_init)
 712 module_exit(sfb_module_exit)
 713
 714 MODULE_DESCRIPTION("Stochastic Fair Blue queue discipline");
 715 MODULE_AUTHOR("Juliusz Chroboczek");
 716 MODULE_AUTHOR("Eric Dumazet");
 717 MODULE_LICENSE("GPL");