net/sched/sch_netem.c

   1 /*
   2  * net/sched/sch_netem.c        Network emulator
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License.
   8  *
   9  *              Many of the algorithms and ideas for this came from
  10  *              NIST Net which is not copyrighted.
  11  *
  12  * Authors:     Stephen Hemminger <shemminger@osdl.org>
  13  *              Catalin(ux aka Dino) BOIE <catab at umbrella dot ro>
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/types.h>
  18 #include <linux/kernel.h>
  19 #include <linux/errno.h>
  20 #include <linux/skbuff.h>
  21 #include <linux/rtnetlink.h>
  22
  23 #include <net/netlink.h>
  24 #include <net/pkt_sched.h>
  25
  26 #define VERSION "1.2"
  27
  28 /*      Network Emulation Queuing algorithm.
  29         ====================================
  30
  31         Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
  32                  Network Emulation Tool
  33                  [2] Luigi Rizzo, DummyNet for FreeBSD
  34
  35          ----------------------------------------------------------------
  36
  37          This started out as a simple way to delay outgoing packets to
  38          test TCP but has grown to include most of the functionality
  39          of a full blown network emulator like NISTnet. It can delay
  40          packets and add random jitter (and correlation). The random
  41          distribution can be loaded from a table as well to provide
  42          normal, Pareto, or experimental curves. Packet loss,
  43          duplication, and reordering can also be emulated.
  44
  45          This qdisc does not do classification that can be handled in
  46          layering other disciplines.  It does not need to do bandwidth
  47          control either since that can be handled by using token
  48          bucket or other rate control.
  49
  50          The simulator is limited by the Linux timer resolution
  51          and will create packet bursts on the HZ boundary (1ms).
  52 */
  53
  54 struct netem_sched_data {
  55         struct Qdisc    *qdisc;
  56         struct qdisc_watchdog watchdog;
  57
  58         psched_tdiff_t latency;
  59         psched_tdiff_t jitter;
  60
  61         u32 loss;
  62         u32 limit;
  63         u32 counter;
  64         u32 gap;
  65         u32 duplicate;
  66         u32 reorder;
  67         u32 corrupt;
  68
  69         struct crndstate {
  70                 u32 last;
  71                 u32 rho;
  72         } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
  73
  74         struct disttable {
  75                 u32  size;
  76                 s16 table[0];
  77         } *delay_dist;
  78 };
  79
  80 /* Time stamp put into socket buffer control block */
  81 struct netem_skb_cb {
  82         psched_time_t   time_to_send;
  83 };
  84
  85 static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
  86 {
  87         BUILD_BUG_ON(sizeof(skb->cb) <
  88                 sizeof(struct qdisc_skb_cb) + sizeof(struct netem_skb_cb));
  89         return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
  90 }
  91
  92 /* init_crandom - initialize correlated random number generator
  93  * Use entropy source for initial seed.
  94  */
  95 static void init_crandom(struct crndstate *state, unsigned long rho)
  96 {
  97         state->rho = rho;
  98         state->last = net_random();
  99 }
 100
 101 /* get_crandom - correlated random number generator
 102  * Next number depends on last value.
 103  * rho is scaled to avoid floating point.
 104  */
 105 static u32 get_crandom(struct crndstate *state)
 106 {
 107         u64 value, rho;
 108         unsigned long answer;
 109
 110         if (state->rho == 0)    /* no correlation */
 111                 return net_random();
 112
 113         value = net_random();
 114         rho = (u64)state->rho + 1;
 115         answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
 116         state->last = answer;
 117         return answer;
 118 }
 119
 120 /* tabledist - return a pseudo-randomly distributed value with mean mu and
 121  * std deviation sigma.  Uses table lookup to approximate the desired
 122  * distribution, and a uniformly-distributed pseudo-random source.
 123  */
 124 static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
 125                                 struct crndstate *state,
 126                                 const struct disttable *dist)
 127 {
 128         psched_tdiff_t x;
 129         long t;
 130         u32 rnd;
 131
 132         if (sigma == 0)
 133                 return mu;
 134
 135         rnd = get_crandom(state);
 136
 137         /* default uniform distribution */
 138         if (dist == NULL)
 139                 return (rnd % (2*sigma)) - sigma + mu;
 140
 141         t = dist->table[rnd % dist->size];
 142         x = (sigma % NETEM_DIST_SCALE) * t;
 143         if (x >= 0)
 144                 x += NETEM_DIST_SCALE/2;
 145         else
 146                 x -= NETEM_DIST_SCALE/2;
 147
 148         return  x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
 149 }
 150
 151 /*
 152  * Insert one skb into qdisc.
 153  * Note: parent depends on return value to account for queue length.
 154  *      NET_XMIT_DROP: queue length didn't change.
 155  *      NET_XMIT_SUCCESS: one skb was queued.
 156  */
 157 static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 158 {
 159         struct netem_sched_data *q = qdisc_priv(sch);
 160         /* We don't fill cb now as skb_unshare() may invalidate it */
 161         struct netem_skb_cb *cb;
 162         struct sk_buff *skb2;
 163         int ret;
 164         int count = 1;
 165
 166         pr_debug("netem_enqueue skb=%p\n", skb);
 167
 168         /* Random duplication */
 169         if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
 170                 ++count;
 171
 172         /* Random packet drop 0 => none, ~0 => all */
 173         if (q->loss && q->loss >= get_crandom(&q->loss_cor))
 174                 --count;
 175
 176         if (count == 0) {
 177                 sch->qstats.drops++;
 178                 kfree_skb(skb);
 179                 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 180         }
 181
 182         skb_orphan(skb);
 183
 184         /*
 185          * If we need to duplicate packet, then re-insert at top of the
 186          * qdisc tree, since parent queuer expects that only one
 187          * skb will be queued.
 188          */
 189         if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
 190                 struct Qdisc *rootq = qdisc_root(sch);
 191                 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
 192                 q->duplicate = 0;
 193
 194                 qdisc_enqueue_root(skb2, rootq);
 195                 q->duplicate = dupsave;
 196         }
 197
 198         /*
 199          * Randomized packet corruption.
 200          * Make copy if needed since we are modifying
 201          * If packet is going to be hardware checksummed, then
 202          * do it now in software before we mangle it.
 203          */
 204         if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
 205                 if (!(skb = skb_unshare(skb, GFP_ATOMIC))
 206                     || (skb->ip_summed == CHECKSUM_PARTIAL
 207                         && skb_checksum_help(skb))) {
 208                         sch->qstats.drops++;
 209                         return NET_XMIT_DROP;
 210                 }
 211
 212                 skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
 213         }
 214
 215         cb = netem_skb_cb(skb);
 216         if (q->gap == 0                 /* not doing reordering */
 217             || q->counter < q->gap      /* inside last reordering gap */
 218             || q->reorder < get_crandom(&q->reorder_cor)) {
 219                 psched_time_t now;
 220                 psched_tdiff_t delay;
 221
 222                 delay = tabledist(q->latency, q->jitter,
 223                                   &q->delay_cor, q->delay_dist);
 224
 225                 now = psched_get_time();
 226                 cb->time_to_send = now + delay;
 227                 ++q->counter;
 228                 ret = qdisc_enqueue(skb, q->qdisc);
 229         } else {
 230                 /*
 231                  * Do re-ordering by putting one out of N packets at the front
 232                  * of the queue.
 233                  */
 234                 cb->time_to_send = psched_get_time();
 235                 q->counter = 0;
 236                 ret = q->qdisc->ops->requeue(skb, q->qdisc);
 237         }
 238
 239         if (likely(ret == NET_XMIT_SUCCESS)) {
 240                 sch->q.qlen++;
 241                 sch->bstats.bytes += qdisc_pkt_len(skb);
 242                 sch->bstats.packets++;
 243         } else if (net_xmit_drop_count(ret)) {
 244                 sch->qstats.drops++;
 245         }
 246
 247         pr_debug("netem: enqueue ret %d\n", ret);
 248         return ret;
 249 }
 250
 251 /* Requeue packets but don't change time stamp */
 252 static int netem_requeue(struct sk_buff *skb, struct Qdisc *sch)
 253 {
 254         struct netem_sched_data *q = qdisc_priv(sch);
 255         int ret;
 256
 257         if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) {
 258                 sch->q.qlen++;
 259                 sch->qstats.requeues++;
 260         }
 261
 262         return ret;
 263 }
 264
 265 static unsigned int netem_drop(struct Qdisc* sch)
 266 {
 267         struct netem_sched_data *q = qdisc_priv(sch);
 268         unsigned int len = 0;
 269
 270         if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
 271                 sch->q.qlen--;
 272                 sch->qstats.drops++;
 273         }
 274         return len;
 275 }
 276
 277 static struct sk_buff *netem_dequeue(struct Qdisc *sch)
 278 {
 279         struct netem_sched_data *q = qdisc_priv(sch);
 280         struct sk_buff *skb;
 281
 282         smp_mb();
 283         if (sch->flags & TCQ_F_THROTTLED)
 284                 return NULL;
 285
 286         skb = q->qdisc->dequeue(q->qdisc);
 287         if (skb) {
 288                 const struct netem_skb_cb *cb = netem_skb_cb(skb);
 289                 psched_time_t now = psched_get_time();
 290
 291                 /* if more time remaining? */
 292                 if (cb->time_to_send <= now) {
 293                         pr_debug("netem_dequeue: return skb=%p\n", skb);
 294                         sch->q.qlen--;
 295                         return skb;
 296                 }
 297
 298                 if (unlikely(q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS)) {
 299                         qdisc_tree_decrease_qlen(q->qdisc, 1);
 300                         sch->qstats.drops++;
 301                         printk(KERN_ERR "netem: %s could not requeue\n",
 302                                q->qdisc->ops->id);
 303                 }
 304
 305                 qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
 306         }
 307
 308         return NULL;
 309 }
 310
 311 static void netem_reset(struct Qdisc *sch)
 312 {
 313         struct netem_sched_data *q = qdisc_priv(sch);
 314
 315         qdisc_reset(q->qdisc);
 316         sch->q.qlen = 0;
 317         qdisc_watchdog_cancel(&q->watchdog);
 318 }
 319
 320 /*
 321  * Distribution data is a variable size payload containing
 322  * signed 16 bit values.
 323  */
 324 static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
 325 {
 326         struct netem_sched_data *q = qdisc_priv(sch);
 327         unsigned long n = nla_len(attr)/sizeof(__s16);
 328         const __s16 *data = nla_data(attr);
 329         spinlock_t *root_lock;
 330         struct disttable *d;
 331         int i;
 332
 333         if (n > 65536)
 334                 return -EINVAL;
 335
 336         d = kmalloc(sizeof(*d) + n*sizeof(d->table[0]), GFP_KERNEL);
 337         if (!d)
 338                 return -ENOMEM;
 339
 340         d->size = n;
 341         for (i = 0; i < n; i++)
 342                 d->table[i] = data[i];
 343
 344         root_lock = qdisc_root_sleeping_lock(sch);
 345
 346         spin_lock_bh(root_lock);
 347         d = xchg(&q->delay_dist, d);
 348         spin_unlock_bh(root_lock);
 349
 350         kfree(d);
 351         return 0;
 352 }
 353
 354 static int get_correlation(struct Qdisc *sch, const struct nlattr *attr)
 355 {
 356         struct netem_sched_data *q = qdisc_priv(sch);
 357         const struct tc_netem_corr *c = nla_data(attr);
 358
 359         init_crandom(&q->delay_cor, c->delay_corr);
 360         init_crandom(&q->loss_cor, c->loss_corr);
 361         init_crandom(&q->dup_cor, c->dup_corr);
 362         return 0;
 363 }
 364
 365 static int get_reorder(struct Qdisc *sch, const struct nlattr *attr)
 366 {
 367         struct netem_sched_data *q = qdisc_priv(sch);
 368         const struct tc_netem_reorder *r = nla_data(attr);
 369
 370         q->reorder = r->probability;
 371         init_crandom(&q->reorder_cor, r->correlation);
 372         return 0;
 373 }
 374
 375 static int get_corrupt(struct Qdisc *sch, const struct nlattr *attr)
 376 {
 377         struct netem_sched_data *q = qdisc_priv(sch);
 378         const struct tc_netem_corrupt *r = nla_data(attr);
 379
 380         q->corrupt = r->probability;
 381         init_crandom(&q->corrupt_cor, r->correlation);
 382         return 0;
 383 }
 384
 385 static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
 386         [TCA_NETEM_CORR]        = { .len = sizeof(struct tc_netem_corr) },
 387         [TCA_NETEM_REORDER]     = { .len = sizeof(struct tc_netem_reorder) },
 388         [TCA_NETEM_CORRUPT]     = { .len = sizeof(struct tc_netem_corrupt) },
 389 };
 390
 391 static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
 392                       const struct nla_policy *policy, int len)
 393 {
 394         int nested_len = nla_len(nla) - NLA_ALIGN(len);
 395
 396         if (nested_len < 0)
 397                 return -EINVAL;
 398         if (nested_len >= nla_attr_size(0))
 399                 return nla_parse(tb, maxtype, nla_data(nla) + NLA_ALIGN(len),
 400                                  nested_len, policy);
 401         memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
 402         return 0;
 403 }
 404
 405 /* Parse netlink message to set options */
 406 static int netem_change(struct Qdisc *sch, struct nlattr *opt)
 407 {
 408         struct netem_sched_data *q = qdisc_priv(sch);
 409         struct nlattr *tb[TCA_NETEM_MAX + 1];
 410         struct tc_netem_qopt *qopt;
 411         int ret;
 412
 413         if (opt == NULL)
 414                 return -EINVAL;
 415
 416         qopt = nla_data(opt);
 417         ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
 418         if (ret < 0)
 419                 return ret;
 420
 421         ret = fifo_set_limit(q->qdisc, qopt->limit);
 422         if (ret) {
 423                 pr_debug("netem: can't set fifo limit\n");
 424                 return ret;
 425         }
 426
 427         q->latency = qopt->latency;
 428         q->jitter = qopt->jitter;
 429         q->limit = qopt->limit;
 430         q->gap = qopt->gap;
 431         q->counter = 0;
 432         q->loss = qopt->loss;
 433         q->duplicate = qopt->duplicate;
 434
 435         /* for compatibility with earlier versions.
 436          * if gap is set, need to assume 100% probability
 437          */
 438         if (q->gap)
 439                 q->reorder = ~0;
 440
 441         if (tb[TCA_NETEM_CORR]) {
 442                 ret = get_correlation(sch, tb[TCA_NETEM_CORR]);
 443                 if (ret)
 444                         return ret;
 445         }
 446
 447         if (tb[TCA_NETEM_DELAY_DIST]) {
 448                 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
 449                 if (ret)
 450                         return ret;
 451         }
 452
 453         if (tb[TCA_NETEM_REORDER]) {
 454                 ret = get_reorder(sch, tb[TCA_NETEM_REORDER]);
 455                 if (ret)
 456                         return ret;
 457         }
 458
 459         if (tb[TCA_NETEM_CORRUPT]) {
 460                 ret = get_corrupt(sch, tb[TCA_NETEM_CORRUPT]);
 461                 if (ret)
 462                         return ret;
 463         }
 464
 465         return 0;
 466 }
 467
 468 /*
 469  * Special case version of FIFO queue for use by netem.
 470  * It queues in order based on timestamps in skb's
 471  */
 472 struct fifo_sched_data {
 473         u32 limit;
 474         psched_time_t oldest;
 475 };
 476
 477 static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
 478 {
 479         struct fifo_sched_data *q = qdisc_priv(sch);
 480         struct sk_buff_head *list = &sch->q;
 481         psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
 482         struct sk_buff *skb;
 483
 484         if (likely(skb_queue_len(list) < q->limit)) {
 485                 /* Optimize for add at tail */
 486                 if (likely(skb_queue_empty(list) || tnext >= q->oldest)) {
 487                         q->oldest = tnext;
 488                         return qdisc_enqueue_tail(nskb, sch);
 489                 }
 490
 491                 skb_queue_reverse_walk(list, skb) {
 492                         const struct netem_skb_cb *cb = netem_skb_cb(skb);
 493
 494                         if (tnext >= cb->time_to_send)
 495                                 break;
 496                 }
 497
 498                 __skb_queue_after(list, skb, nskb);
 499
 500                 sch->qstats.backlog += qdisc_pkt_len(nskb);
 501                 sch->bstats.bytes += qdisc_pkt_len(nskb);
 502                 sch->bstats.packets++;
 503
 504                 return NET_XMIT_SUCCESS;
 505         }
 506
 507         return qdisc_reshape_fail(nskb, sch);
 508 }
 509
 510 static int tfifo_init(struct Qdisc *sch, struct nlattr *opt)
 511 {
 512         struct fifo_sched_data *q = qdisc_priv(sch);
 513
 514         if (opt) {
 515                 struct tc_fifo_qopt *ctl = nla_data(opt);
 516                 if (nla_len(opt) < sizeof(*ctl))
 517                         return -EINVAL;
 518
 519                 q->limit = ctl->limit;
 520         } else
 521                 q->limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
 522
 523         q->oldest = PSCHED_PASTPERFECT;
 524         return 0;
 525 }
 526
 527 static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb)
 528 {
 529         struct fifo_sched_data *q = qdisc_priv(sch);
 530         struct tc_fifo_qopt opt = { .limit = q->limit };
 531
 532         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 533         return skb->len;
 534
 535 nla_put_failure:
 536         return -1;
 537 }
 538
 539 static struct Qdisc_ops tfifo_qdisc_ops __read_mostly = {
 540         .id             =       "tfifo",
 541         .priv_size      =       sizeof(struct fifo_sched_data),
 542         .enqueue        =       tfifo_enqueue,
 543         .dequeue        =       qdisc_dequeue_head,
 544         .requeue        =       qdisc_requeue,
 545         .drop           =       qdisc_queue_drop,
 546         .init           =       tfifo_init,
 547         .reset          =       qdisc_reset_queue,
 548         .change         =       tfifo_init,
 549         .dump           =       tfifo_dump,
 550 };
 551
 552 static int netem_init(struct Qdisc *sch, struct nlattr *opt)
 553 {
 554         struct netem_sched_data *q = qdisc_priv(sch);
 555         int ret;
 556
 557         if (!opt)
 558                 return -EINVAL;
 559
 560         qdisc_watchdog_init(&q->watchdog, sch);
 561
 562         q->qdisc = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
 563                                      &tfifo_qdisc_ops,
 564                                      TC_H_MAKE(sch->handle, 1));
 565         if (!q->qdisc) {
 566                 pr_debug("netem: qdisc create failed\n");
 567                 return -ENOMEM;
 568         }
 569
 570         ret = netem_change(sch, opt);
 571         if (ret) {
 572                 pr_debug("netem: change failed\n");
 573                 qdisc_destroy(q->qdisc);
 574         }
 575         return ret;
 576 }
 577
 578 static void netem_destroy(struct Qdisc *sch)
 579 {
 580         struct netem_sched_data *q = qdisc_priv(sch);
 581
 582         qdisc_watchdog_cancel(&q->watchdog);
 583         qdisc_destroy(q->qdisc);
 584         kfree(q->delay_dist);
 585 }
 586
 587 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
 588 {
 589         const struct netem_sched_data *q = qdisc_priv(sch);
 590         unsigned char *b = skb_tail_pointer(skb);
 591         struct nlattr *nla = (struct nlattr *) b;
 592         struct tc_netem_qopt qopt;
 593         struct tc_netem_corr cor;
 594         struct tc_netem_reorder reorder;
 595         struct tc_netem_corrupt corrupt;
 596
 597         qopt.latency = q->latency;
 598         qopt.jitter = q->jitter;
 599         qopt.limit = q->limit;
 600         qopt.loss = q->loss;
 601         qopt.gap = q->gap;
 602         qopt.duplicate = q->duplicate;
 603         NLA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
 604
 605         cor.delay_corr = q->delay_cor.rho;
 606         cor.loss_corr = q->loss_cor.rho;
 607         cor.dup_corr = q->dup_cor.rho;
 608         NLA_PUT(skb, TCA_NETEM_CORR, sizeof(cor), &cor);
 609
 610         reorder.probability = q->reorder;
 611         reorder.correlation = q->reorder_cor.rho;
 612         NLA_PUT(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder);
 613
 614         corrupt.probability = q->corrupt;
 615         corrupt.correlation = q->corrupt_cor.rho;
 616         NLA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);
 617
 618         nla->nla_len = skb_tail_pointer(skb) - b;
 619
 620         return skb->len;
 621
 622 nla_put_failure:
 623         nlmsg_trim(skb, b);
 624         return -1;
 625 }
 626
 627 static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
 628                           struct sk_buff *skb, struct tcmsg *tcm)
 629 {
 630         struct netem_sched_data *q = qdisc_priv(sch);
 631
 632         if (cl != 1)    /* only one class */
 633                 return -ENOENT;
 634
 635         tcm->tcm_handle |= TC_H_MIN(1);
 636         tcm->tcm_info = q->qdisc->handle;
 637
 638         return 0;
 639 }
 640
 641 static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 642                      struct Qdisc **old)
 643 {
 644         struct netem_sched_data *q = qdisc_priv(sch);
 645
 646         if (new == NULL)
 647                 new = &noop_qdisc;
 648
 649         sch_tree_lock(sch);
 650         *old = xchg(&q->qdisc, new);
 651         qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
 652         qdisc_reset(*old);
 653         sch_tree_unlock(sch);
 654
 655         return 0;
 656 }
 657
 658 static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
 659 {
 660         struct netem_sched_data *q = qdisc_priv(sch);
 661         return q->qdisc;
 662 }
 663
 664 static unsigned long netem_get(struct Qdisc *sch, u32 classid)
 665 {
 666         return 1;
 667 }
 668
 669 static void netem_put(struct Qdisc *sch, unsigned long arg)
 670 {
 671 }
 672
 673 static int netem_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 674                             struct nlattr **tca, unsigned long *arg)
 675 {
 676         return -ENOSYS;
 677 }
 678
 679 static int netem_delete(struct Qdisc *sch, unsigned long arg)
 680 {
 681         return -ENOSYS;
 682 }
 683
 684 static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 685 {
 686         if (!walker->stop) {
 687                 if (walker->count >= walker->skip)
 688                         if (walker->fn(sch, 1, walker) < 0) {
 689                                 walker->stop = 1;
 690                                 return;
 691                         }
 692                 walker->count++;
 693         }
 694 }
 695
 696 static struct tcf_proto **netem_find_tcf(struct Qdisc *sch, unsigned long cl)
 697 {
 698         return NULL;
 699 }
 700
 701 static const struct Qdisc_class_ops netem_class_ops = {
 702         .graft          =       netem_graft,
 703         .leaf           =       netem_leaf,
 704         .get            =       netem_get,
 705         .put            =       netem_put,
 706         .change         =       netem_change_class,
 707         .delete         =       netem_delete,
 708         .walk           =       netem_walk,
 709         .tcf_chain      =       netem_find_tcf,
 710         .dump           =       netem_dump_class,
 711 };
 712
 713 static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
 714         .id             =       "netem",
 715         .cl_ops         =       &netem_class_ops,
 716         .priv_size      =       sizeof(struct netem_sched_data),
 717         .enqueue        =       netem_enqueue,
 718         .dequeue        =       netem_dequeue,
 719         .requeue        =       netem_requeue,
 720         .drop           =       netem_drop,
 721         .init           =       netem_init,
 722         .reset          =       netem_reset,
 723         .destroy        =       netem_destroy,
 724         .change         =       netem_change,
 725         .dump           =       netem_dump,
 726         .owner          =       THIS_MODULE,
 727 };
 728
 729
 730 static int __init netem_module_init(void)
 731 {
 732         pr_info("netem: version " VERSION "\n");
 733         return register_qdisc(&netem_qdisc_ops);
 734 }
 735 static void __exit netem_module_exit(void)
 736 {
 737         unregister_qdisc(&netem_qdisc_ops);
 738 }
 739 module_init(netem_module_init)
 740 module_exit(netem_module_exit)
 741 MODULE_LICENSE("GPL");