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 #include <net/flow_keys.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         unsigned long   rehash_interval;
  60         unsigned long   warmup_time;    /* double buffering warmup time in jiffies */
  61         u32             max;
  62         u32             bin_size;       /* maximum queue length per bin */
  63         u32             increment;      /* d1 */
  64         u32             decrement;      /* d2 */
  65         u32             limit;          /* HARD maximal queue length */
  66         u32             penalty_rate;
  67         u32             penalty_burst;
  68         u32             tokens_avail;
  69         unsigned long   rehash_time;
  70         unsigned long   token_time;
  71
  72         u8              slot;           /* current active bins (0 or 1) */
  73         bool            double_buffering;
  74         struct sfb_bins bins[2];
  75
  76         struct {
  77                 u32     earlydrop;
  78                 u32     penaltydrop;
  79                 u32     bucketdrop;
  80                 u32     queuedrop;
  81                 u32     childdrop;      /* drops in child qdisc */
  82                 u32     marked;         /* ECN mark */
  83         } stats;
  84 };
  85
  86 /*
  87  * Each queued skb might be hashed on one or two bins
  88  * We store in skb_cb the two hash values.
  89  * (A zero value means double buffering was not used)
  90  */
  91 struct sfb_skb_cb {
  92         u32 hashes[2];
  93 };
  94
  95 static inline struct sfb_skb_cb *sfb_skb_cb(const struct sk_buff *skb)
  96 {
  97         qdisc_cb_private_validate(skb, 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 = prandom_u32();
 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 tcf_proto *fl,
 257                          int *qerr, u32 *salt)
 258 {
 259         struct tcf_result res;
 260         int result;
 261
 262         result = tc_classify(skb, fl, &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         struct tcf_proto *fl;
 285         int i;
 286         u32 p_min = ~0;
 287         u32 minqlen = ~0;
 288         u32 r, slot, salt, sfbhash;
 289         int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 290         struct flow_keys keys;
 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                 /* If using external classifiers, get result and record it. */
 313                 if (!sfb_classify(skb, fl, &ret, &salt))
 314                         goto other_drop;
 315                 keys.src = salt;
 316                 keys.dst = 0;
 317                 keys.ports = 0;
 318         } else {
 319                 skb_flow_dissect(skb, &keys);
 320         }
 321
 322         slot = q->slot;
 323
 324         sfbhash = jhash_3words((__force u32)keys.dst,
 325                                (__force u32)keys.src,
 326                                (__force u32)keys.ports,
 327                                q->bins[slot].perturbation);
 328         if (!sfbhash)
 329                 sfbhash = 1;
 330         sfb_skb_cb(skb)->hashes[slot] = sfbhash;
 331
 332         for (i = 0; i < SFB_LEVELS; i++) {
 333                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 334                 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
 335
 336                 sfbhash >>= SFB_BUCKET_SHIFT;
 337                 if (b->qlen == 0)
 338                         decrement_prob(b, q);
 339                 else if (b->qlen >= q->bin_size)
 340                         increment_prob(b, q);
 341                 if (minqlen > b->qlen)
 342                         minqlen = b->qlen;
 343                 if (p_min > b->p_mark)
 344                         p_min = b->p_mark;
 345         }
 346
 347         slot ^= 1;
 348         sfb_skb_cb(skb)->hashes[slot] = 0;
 349
 350         if (unlikely(minqlen >= q->max)) {
 351                 qdisc_qstats_overlimit(sch);
 352                 q->stats.bucketdrop++;
 353                 goto drop;
 354         }
 355
 356         if (unlikely(p_min >= SFB_MAX_PROB)) {
 357                 /* Inelastic flow */
 358                 if (q->double_buffering) {
 359                         sfbhash = jhash_3words((__force u32)keys.dst,
 360                                                (__force u32)keys.src,
 361                                                (__force u32)keys.ports,
 362                                                q->bins[slot].perturbation);
 363                         if (!sfbhash)
 364                                 sfbhash = 1;
 365                         sfb_skb_cb(skb)->hashes[slot] = sfbhash;
 366
 367                         for (i = 0; i < SFB_LEVELS; i++) {
 368                                 u32 hash = sfbhash & SFB_BUCKET_MASK;
 369                                 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
 370
 371                                 sfbhash >>= SFB_BUCKET_SHIFT;
 372                                 if (b->qlen == 0)
 373                                         decrement_prob(b, q);
 374                                 else if (b->qlen >= q->bin_size)
 375                                         increment_prob(b, q);
 376                         }
 377                 }
 378                 if (sfb_rate_limit(skb, q)) {
 379                         qdisc_qstats_overlimit(sch);
 380                         q->stats.penaltydrop++;
 381                         goto drop;
 382                 }
 383                 goto enqueue;
 384         }
 385
 386         r = prandom_u32() & SFB_MAX_PROB;
 387
 388         if (unlikely(r < p_min)) {
 389                 if (unlikely(p_min > SFB_MAX_PROB / 2)) {
 390                         /* If we're marking that many packets, then either
 391                          * this flow is unresponsive, or we're badly congested.
 392                          * In either case, we want to start dropping packets.
 393                          */
 394                         if (r < (p_min - SFB_MAX_PROB / 2) * 2) {
 395                                 q->stats.earlydrop++;
 396                                 goto drop;
 397                         }
 398                 }
 399                 if (INET_ECN_set_ce(skb)) {
 400                         q->stats.marked++;
 401                 } else {
 402                         q->stats.earlydrop++;
 403                         goto drop;
 404                 }
 405         }
 406
 407 enqueue:
 408         ret = qdisc_enqueue(skb, child);
 409         if (likely(ret == NET_XMIT_SUCCESS)) {
 410                 sch->q.qlen++;
 411                 increment_qlen(skb, q);
 412         } else if (net_xmit_drop_count(ret)) {
 413                 q->stats.childdrop++;
 414                 qdisc_qstats_drop(sch);
 415         }
 416         return ret;
 417
 418 drop:
 419         qdisc_drop(skb, sch);
 420         return NET_XMIT_CN;
 421 other_drop:
 422         if (ret & __NET_XMIT_BYPASS)
 423                 qdisc_qstats_drop(sch);
 424         kfree_skb(skb);
 425         return ret;
 426 }
 427
 428 static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
 429 {
 430         struct sfb_sched_data *q = qdisc_priv(sch);
 431         struct Qdisc *child = q->qdisc;
 432         struct sk_buff *skb;
 433
 434         skb = child->dequeue(q->qdisc);
 435
 436         if (skb) {
 437                 qdisc_bstats_update(sch, skb);
 438                 sch->q.qlen--;
 439                 decrement_qlen(skb, q);
 440         }
 441
 442         return skb;
 443 }
 444
 445 static struct sk_buff *sfb_peek(struct Qdisc *sch)
 446 {
 447         struct sfb_sched_data *q = qdisc_priv(sch);
 448         struct Qdisc *child = q->qdisc;
 449
 450         return child->ops->peek(child);
 451 }
 452
 453 /* No sfb_drop -- impossible since the child doesn't return the dropped skb. */
 454
 455 static void sfb_reset(struct Qdisc *sch)
 456 {
 457         struct sfb_sched_data *q = qdisc_priv(sch);
 458
 459         qdisc_reset(q->qdisc);
 460         sch->q.qlen = 0;
 461         q->slot = 0;
 462         q->double_buffering = false;
 463         sfb_zero_all_buckets(q);
 464         sfb_init_perturbation(0, q);
 465 }
 466
 467 static void sfb_destroy(struct Qdisc *sch)
 468 {
 469         struct sfb_sched_data *q = qdisc_priv(sch);
 470
 471         tcf_destroy_chain(&q->filter_list);
 472         qdisc_destroy(q->qdisc);
 473 }
 474
 475 static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
 476         [TCA_SFB_PARMS] = { .len = sizeof(struct tc_sfb_qopt) },
 477 };
 478
 479 static const struct tc_sfb_qopt sfb_default_ops = {
 480         .rehash_interval = 600 * MSEC_PER_SEC,
 481         .warmup_time = 60 * MSEC_PER_SEC,
 482         .limit = 0,
 483         .max = 25,
 484         .bin_size = 20,
 485         .increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
 486         .decrement = (SFB_MAX_PROB + 3000) / 6000,
 487         .penalty_rate = 10,
 488         .penalty_burst = 20,
 489 };
 490
 491 static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
 492 {
 493         struct sfb_sched_data *q = qdisc_priv(sch);
 494         struct Qdisc *child;
 495         struct nlattr *tb[TCA_SFB_MAX + 1];
 496         const struct tc_sfb_qopt *ctl = &sfb_default_ops;
 497         u32 limit;
 498         int err;
 499
 500         if (opt) {
 501                 err = nla_parse_nested(tb, TCA_SFB_MAX, opt, sfb_policy);
 502                 if (err < 0)
 503                         return -EINVAL;
 504
 505                 if (tb[TCA_SFB_PARMS] == NULL)
 506                         return -EINVAL;
 507
 508                 ctl = nla_data(tb[TCA_SFB_PARMS]);
 509         }
 510
 511         limit = ctl->limit;
 512         if (limit == 0)
 513                 limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
 514
 515         child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
 516         if (IS_ERR(child))
 517                 return PTR_ERR(child);
 518
 519         sch_tree_lock(sch);
 520
 521         qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
 522         qdisc_destroy(q->qdisc);
 523         q->qdisc = child;
 524
 525         q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
 526         q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
 527         q->rehash_time = jiffies;
 528         q->limit = limit;
 529         q->increment = ctl->increment;
 530         q->decrement = ctl->decrement;
 531         q->max = ctl->max;
 532         q->bin_size = ctl->bin_size;
 533         q->penalty_rate = ctl->penalty_rate;
 534         q->penalty_burst = ctl->penalty_burst;
 535         q->tokens_avail = ctl->penalty_burst;
 536         q->token_time = jiffies;
 537
 538         q->slot = 0;
 539         q->double_buffering = false;
 540         sfb_zero_all_buckets(q);
 541         sfb_init_perturbation(0, q);
 542         sfb_init_perturbation(1, q);
 543
 544         sch_tree_unlock(sch);
 545
 546         return 0;
 547 }
 548
 549 static int sfb_init(struct Qdisc *sch, struct nlattr *opt)
 550 {
 551         struct sfb_sched_data *q = qdisc_priv(sch);
 552
 553         q->qdisc = &noop_qdisc;
 554         return sfb_change(sch, opt);
 555 }
 556
 557 static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
 558 {
 559         struct sfb_sched_data *q = qdisc_priv(sch);
 560         struct nlattr *opts;
 561         struct tc_sfb_qopt opt = {
 562                 .rehash_interval = jiffies_to_msecs(q->rehash_interval),
 563                 .warmup_time = jiffies_to_msecs(q->warmup_time),
 564                 .limit = q->limit,
 565                 .max = q->max,
 566                 .bin_size = q->bin_size,
 567                 .increment = q->increment,
 568                 .decrement = q->decrement,
 569                 .penalty_rate = q->penalty_rate,
 570                 .penalty_burst = q->penalty_burst,
 571         };
 572
 573         sch->qstats.backlog = q->qdisc->qstats.backlog;
 574         opts = nla_nest_start(skb, TCA_OPTIONS);
 575         if (opts == NULL)
 576                 goto nla_put_failure;
 577         if (nla_put(skb, TCA_SFB_PARMS, sizeof(opt), &opt))
 578                 goto nla_put_failure;
 579         return nla_nest_end(skb, opts);
 580
 581 nla_put_failure:
 582         nla_nest_cancel(skb, opts);
 583         return -EMSGSIZE;
 584 }
 585
 586 static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 587 {
 588         struct sfb_sched_data *q = qdisc_priv(sch);
 589         struct tc_sfb_xstats st = {
 590                 .earlydrop = q->stats.earlydrop,
 591                 .penaltydrop = q->stats.penaltydrop,
 592                 .bucketdrop = q->stats.bucketdrop,
 593                 .queuedrop = q->stats.queuedrop,
 594                 .childdrop = q->stats.childdrop,
 595                 .marked = q->stats.marked,
 596         };
 597
 598         st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);
 599
 600         return gnet_stats_copy_app(d, &st, sizeof(st));
 601 }
 602
 603 static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
 604                           struct sk_buff *skb, struct tcmsg *tcm)
 605 {
 606         return -ENOSYS;
 607 }
 608
 609 static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 610                      struct Qdisc **old)
 611 {
 612         struct sfb_sched_data *q = qdisc_priv(sch);
 613
 614         if (new == NULL)
 615                 new = &noop_qdisc;
 616
 617         sch_tree_lock(sch);
 618         *old = q->qdisc;
 619         q->qdisc = new;
 620         qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
 621         qdisc_reset(*old);
 622         sch_tree_unlock(sch);
 623         return 0;
 624 }
 625
 626 static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
 627 {
 628         struct sfb_sched_data *q = qdisc_priv(sch);
 629
 630         return q->qdisc;
 631 }
 632
 633 static unsigned long sfb_get(struct Qdisc *sch, u32 classid)
 634 {
 635         return 1;
 636 }
 637
 638 static void sfb_put(struct Qdisc *sch, unsigned long arg)
 639 {
 640 }
 641
 642 static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 643                             struct nlattr **tca, unsigned long *arg)
 644 {
 645         return -ENOSYS;
 646 }
 647
 648 static int sfb_delete(struct Qdisc *sch, unsigned long cl)
 649 {
 650         return -ENOSYS;
 651 }
 652
 653 static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 654 {
 655         if (!walker->stop) {
 656                 if (walker->count >= walker->skip)
 657                         if (walker->fn(sch, 1, walker) < 0) {
 658                                 walker->stop = 1;
 659                                 return;
 660                         }
 661                 walker->count++;
 662         }
 663 }
 664
 665 static struct tcf_proto __rcu **sfb_find_tcf(struct Qdisc *sch,
 666                                              unsigned long cl)
 667 {
 668         struct sfb_sched_data *q = qdisc_priv(sch);
 669
 670         if (cl)
 671                 return NULL;
 672         return &q->filter_list;
 673 }
 674
 675 static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
 676                               u32 classid)
 677 {
 678         return 0;
 679 }
 680
 681
 682 static const struct Qdisc_class_ops sfb_class_ops = {
 683         .graft          =       sfb_graft,
 684         .leaf           =       sfb_leaf,
 685         .get            =       sfb_get,
 686         .put            =       sfb_put,
 687         .change         =       sfb_change_class,
 688         .delete         =       sfb_delete,
 689         .walk           =       sfb_walk,
 690         .tcf_chain      =       sfb_find_tcf,
 691         .bind_tcf       =       sfb_bind,
 692         .unbind_tcf     =       sfb_put,
 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");