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/bitops.h>
  18 #include <linux/types.h>
  19 #include <linux/kernel.h>
  20 #include <linux/errno.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/rtnetlink.h>
  24
  25 #include <net/pkt_sched.h>
  26
  27 #define VERSION "1.2"
  28
  29 /*      Network Emulation Queuing algorithm.
  30         ====================================
  31
  32         Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
  33                  Network Emulation Tool
  34                  [2] Luigi Rizzo, DummyNet for FreeBSD
  35
  36          ----------------------------------------------------------------
  37
  38          This started out as a simple way to delay outgoing packets to
  39          test TCP but has grown to include most of the functionality
  40          of a full blown network emulator like NISTnet. It can delay
  41          packets and add random jitter (and correlation). The random
  42          distribution can be loaded from a table as well to provide
  43          normal, Pareto, or experimental curves. Packet loss,
  44          duplication, and reordering can also be emulated.
  45
  46          This qdisc does not do classification that can be handled in
  47          layering other disciplines.  It does not need to do bandwidth
  48          control either since that can be handled by using token
  49          bucket or other rate control.
  50
  51          The simulator is limited by the Linux timer resolution
  52          and will create packet bursts on the HZ boundary (1ms).
  53 */
  54
  55 struct netem_sched_data {
  56         struct Qdisc    *qdisc;
  57         struct timer_list timer;
  58
  59         u32 latency;
  60         u32 loss;
  61         u32 limit;
  62         u32 counter;
  63         u32 gap;
  64         u32 jitter;
  65         u32 duplicate;
  66         u32 reorder;
  67         u32 corrupt;
  68
  69         struct crndstate {
  70                 unsigned long last;
  71                 unsigned long 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 /* init_crandom - initialize correlated random number generator
  86  * Use entropy source for initial seed.
  87  */
  88 static void init_crandom(struct crndstate *state, unsigned long rho)
  89 {
  90         state->rho = rho;
  91         state->last = net_random();
  92 }
  93
  94 /* get_crandom - correlated random number generator
  95  * Next number depends on last value.
  96  * rho is scaled to avoid floating point.
  97  */
  98 static unsigned long get_crandom(struct crndstate *state)
  99 {
 100         u64 value, rho;
 101         unsigned long answer;
 102
 103         if (state->rho == 0)    /* no correllation */
 104                 return net_random();
 105
 106         value = net_random();
 107         rho = (u64)state->rho + 1;
 108         answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
 109         state->last = answer;
 110         return answer;
 111 }
 112
 113 /* tabledist - return a pseudo-randomly distributed value with mean mu and
 114  * std deviation sigma.  Uses table lookup to approximate the desired
 115  * distribution, and a uniformly-distributed pseudo-random source.
 116  */
 117 static long tabledist(unsigned long mu, long sigma,
 118                       struct crndstate *state, const struct disttable *dist)
 119 {
 120         long t, x;
 121         unsigned long rnd;
 122
 123         if (sigma == 0)
 124                 return mu;
 125
 126         rnd = get_crandom(state);
 127
 128         /* default uniform distribution */
 129         if (dist == NULL)
 130                 return (rnd % (2*sigma)) - sigma + mu;
 131
 132         t = dist->table[rnd % dist->size];
 133         x = (sigma % NETEM_DIST_SCALE) * t;
 134         if (x >= 0)
 135                 x += NETEM_DIST_SCALE/2;
 136         else
 137                 x -= NETEM_DIST_SCALE/2;
 138
 139         return  x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
 140 }
 141
 142 /*
 143  * Insert one skb into qdisc.
 144  * Note: parent depends on return value to account for queue length.
 145  *      NET_XMIT_DROP: queue length didn't change.
 146  *      NET_XMIT_SUCCESS: one skb was queued.
 147  */
 148 static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 149 {
 150         struct netem_sched_data *q = qdisc_priv(sch);
 151         /* We don't fill cb now as skb_unshare() may invalidate it */
 152         struct netem_skb_cb *cb;
 153         struct sk_buff *skb2;
 154         int ret;
 155         int count = 1;
 156
 157         pr_debug("netem_enqueue skb=%p\n", skb);
 158
 159         /* Random duplication */
 160         if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
 161                 ++count;
 162
 163         /* Random packet drop 0 => none, ~0 => all */
 164         if (q->loss && q->loss >= get_crandom(&q->loss_cor))
 165                 --count;
 166
 167         if (count == 0) {
 168                 sch->qstats.drops++;
 169                 kfree_skb(skb);
 170                 return NET_XMIT_BYPASS;
 171         }
 172
 173         skb_orphan(skb);
 174
 175         /*
 176          * If we need to duplicate packet, then re-insert at top of the
 177          * qdisc tree, since parent queuer expects that only one
 178          * skb will be queued.
 179          */
 180         if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
 181                 struct Qdisc *rootq = sch->dev->qdisc;
 182                 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
 183                 q->duplicate = 0;
 184
 185                 rootq->enqueue(skb2, rootq);
 186                 q->duplicate = dupsave;
 187         }
 188
 189         /*
 190          * Randomized packet corruption.
 191          * Make copy if needed since we are modifying
 192          * If packet is going to be hardware checksummed, then
 193          * do it now in software before we mangle it.
 194          */
 195         if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
 196                 if (!(skb = skb_unshare(skb, GFP_ATOMIC))
 197                     || (skb->ip_summed == CHECKSUM_PARTIAL
 198                         && skb_checksum_help(skb))) {
 199                         sch->qstats.drops++;
 200                         return NET_XMIT_DROP;
 201                 }
 202
 203                 skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
 204         }
 205
 206         cb = (struct netem_skb_cb *)skb->cb;
 207         if (q->gap == 0                 /* not doing reordering */
 208             || q->counter < q->gap      /* inside last reordering gap */
 209             || q->reorder < get_crandom(&q->reorder_cor)) {
 210                 psched_time_t now;
 211                 psched_tdiff_t delay;
 212
 213                 delay = tabledist(q->latency, q->jitter,
 214                                   &q->delay_cor, q->delay_dist);
 215
 216                 PSCHED_GET_TIME(now);
 217                 PSCHED_TADD2(now, delay, cb->time_to_send);
 218                 ++q->counter;
 219                 ret = q->qdisc->enqueue(skb, q->qdisc);
 220         } else {
 221                 /*
 222                  * Do re-ordering by putting one out of N packets at the front
 223                  * of the queue.
 224                  */
 225                 PSCHED_GET_TIME(cb->time_to_send);
 226                 q->counter = 0;
 227                 ret = q->qdisc->ops->requeue(skb, q->qdisc);
 228         }
 229
 230         if (likely(ret == NET_XMIT_SUCCESS)) {
 231                 sch->q.qlen++;
 232                 sch->bstats.bytes += skb->len;
 233                 sch->bstats.packets++;
 234         } else
 235                 sch->qstats.drops++;
 236
 237         pr_debug("netem: enqueue ret %d\n", ret);
 238         return ret;
 239 }
 240
 241 /* Requeue packets but don't change time stamp */
 242 static int netem_requeue(struct sk_buff *skb, struct Qdisc *sch)
 243 {
 244         struct netem_sched_data *q = qdisc_priv(sch);
 245         int ret;
 246
 247         if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) {
 248                 sch->q.qlen++;
 249                 sch->qstats.requeues++;
 250         }
 251
 252         return ret;
 253 }
 254
 255 static unsigned int netem_drop(struct Qdisc* sch)
 256 {
 257         struct netem_sched_data *q = qdisc_priv(sch);
 258         unsigned int len = 0;
 259
 260         if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
 261                 sch->q.qlen--;
 262                 sch->qstats.drops++;
 263         }
 264         return len;
 265 }
 266
 267 static struct sk_buff *netem_dequeue(struct Qdisc *sch)
 268 {
 269         struct netem_sched_data *q = qdisc_priv(sch);
 270         struct sk_buff *skb;
 271
 272         skb = q->qdisc->dequeue(q->qdisc);
 273         if (skb) {
 274                 const struct netem_skb_cb *cb
 275                         = (const struct netem_skb_cb *)skb->cb;
 276                 psched_time_t now;
 277
 278                 /* if more time remaining? */
 279                 PSCHED_GET_TIME(now);
 280
 281                 if (PSCHED_TLESS(cb->time_to_send, now)) {
 282                         pr_debug("netem_dequeue: return skb=%p\n", skb);
 283                         sch->q.qlen--;
 284                         sch->flags &= ~TCQ_F_THROTTLED;
 285                         return skb;
 286                 } else {
 287                         psched_tdiff_t delay = PSCHED_TDIFF(cb->time_to_send, now);
 288
 289                         if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
 290                                 qdisc_tree_decrease_qlen(q->qdisc, 1);
 291                                 sch->qstats.drops++;
 292                                 printk(KERN_ERR "netem: queue discpline %s could not requeue\n",
 293                                        q->qdisc->ops->id);
 294                         }
 295
 296                         mod_timer(&q->timer, jiffies + PSCHED_US2JIFFIE(delay));
 297                         sch->flags |= TCQ_F_THROTTLED;
 298                 }
 299         }
 300
 301         return NULL;
 302 }
 303
 304 static void netem_watchdog(unsigned long arg)
 305 {
 306         struct Qdisc *sch = (struct Qdisc *)arg;
 307
 308         pr_debug("netem_watchdog qlen=%d\n", sch->q.qlen);
 309         sch->flags &= ~TCQ_F_THROTTLED;
 310         netif_schedule(sch->dev);
 311 }
 312
 313 static void netem_reset(struct Qdisc *sch)
 314 {
 315         struct netem_sched_data *q = qdisc_priv(sch);
 316
 317         qdisc_reset(q->qdisc);
 318         sch->q.qlen = 0;
 319         sch->flags &= ~TCQ_F_THROTTLED;
 320         del_timer_sync(&q->timer);
 321 }
 322
 323 /* Pass size change message down to embedded FIFO */
 324 static int set_fifo_limit(struct Qdisc *q, int limit)
 325 {
 326         struct rtattr *rta;
 327         int ret = -ENOMEM;
 328
 329         /* Hack to avoid sending change message to non-FIFO */
 330         if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
 331                 return 0;
 332
 333         rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
 334         if (rta) {
 335                 rta->rta_type = RTM_NEWQDISC;
 336                 rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt));
 337                 ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit;
 338
 339                 ret = q->ops->change(q, rta);
 340                 kfree(rta);
 341         }
 342         return ret;
 343 }
 344
 345 /*
 346  * Distribution data is a variable size payload containing
 347  * signed 16 bit values.
 348  */
 349 static int get_dist_table(struct Qdisc *sch, const struct rtattr *attr)
 350 {
 351         struct netem_sched_data *q = qdisc_priv(sch);
 352         unsigned long n = RTA_PAYLOAD(attr)/sizeof(__s16);
 353         const __s16 *data = RTA_DATA(attr);
 354         struct disttable *d;
 355         int i;
 356
 357         if (n > 65536)
 358                 return -EINVAL;
 359
 360         d = kmalloc(sizeof(*d) + n*sizeof(d->table[0]), GFP_KERNEL);
 361         if (!d)
 362                 return -ENOMEM;
 363
 364         d->size = n;
 365         for (i = 0; i < n; i++)
 366                 d->table[i] = data[i];
 367
 368         spin_lock_bh(&sch->dev->queue_lock);
 369         d = xchg(&q->delay_dist, d);
 370         spin_unlock_bh(&sch->dev->queue_lock);
 371
 372         kfree(d);
 373         return 0;
 374 }
 375
 376 static int get_correlation(struct Qdisc *sch, const struct rtattr *attr)
 377 {
 378         struct netem_sched_data *q = qdisc_priv(sch);
 379         const struct tc_netem_corr *c = RTA_DATA(attr);
 380
 381         if (RTA_PAYLOAD(attr) != sizeof(*c))
 382                 return -EINVAL;
 383
 384         init_crandom(&q->delay_cor, c->delay_corr);
 385         init_crandom(&q->loss_cor, c->loss_corr);
 386         init_crandom(&q->dup_cor, c->dup_corr);
 387         return 0;
 388 }
 389
 390 static int get_reorder(struct Qdisc *sch, const struct rtattr *attr)
 391 {
 392         struct netem_sched_data *q = qdisc_priv(sch);
 393         const struct tc_netem_reorder *r = RTA_DATA(attr);
 394
 395         if (RTA_PAYLOAD(attr) != sizeof(*r))
 396                 return -EINVAL;
 397
 398         q->reorder = r->probability;
 399         init_crandom(&q->reorder_cor, r->correlation);
 400         return 0;
 401 }
 402
 403 static int get_corrupt(struct Qdisc *sch, const struct rtattr *attr)
 404 {
 405         struct netem_sched_data *q = qdisc_priv(sch);
 406         const struct tc_netem_corrupt *r = RTA_DATA(attr);
 407
 408         if (RTA_PAYLOAD(attr) != sizeof(*r))
 409                 return -EINVAL;
 410
 411         q->corrupt = r->probability;
 412         init_crandom(&q->corrupt_cor, r->correlation);
 413         return 0;
 414 }
 415
 416 /* Parse netlink message to set options */
 417 static int netem_change(struct Qdisc *sch, struct rtattr *opt)
 418 {
 419         struct netem_sched_data *q = qdisc_priv(sch);
 420         struct tc_netem_qopt *qopt;
 421         int ret;
 422
 423         if (opt == NULL || RTA_PAYLOAD(opt) < sizeof(*qopt))
 424                 return -EINVAL;
 425
 426         qopt = RTA_DATA(opt);
 427         ret = set_fifo_limit(q->qdisc, qopt->limit);
 428         if (ret) {
 429                 pr_debug("netem: can't set fifo limit\n");
 430                 return ret;
 431         }
 432
 433         q->latency = qopt->latency;
 434         q->jitter = qopt->jitter;
 435         q->limit = qopt->limit;
 436         q->gap = qopt->gap;
 437         q->counter = 0;
 438         q->loss = qopt->loss;
 439         q->duplicate = qopt->duplicate;
 440
 441         /* for compatiablity with earlier versions.
 442          * if gap is set, need to assume 100% probablity
 443          */
 444         q->reorder = ~0;
 445
 446         /* Handle nested options after initial queue options.
 447          * Should have put all options in nested format but too late now.
 448          */
 449         if (RTA_PAYLOAD(opt) > sizeof(*qopt)) {
 450                 struct rtattr *tb[TCA_NETEM_MAX];
 451                 if (rtattr_parse(tb, TCA_NETEM_MAX,
 452                                  RTA_DATA(opt) + sizeof(*qopt),
 453                                  RTA_PAYLOAD(opt) - sizeof(*qopt)))
 454                         return -EINVAL;
 455
 456                 if (tb[TCA_NETEM_CORR-1]) {
 457                         ret = get_correlation(sch, tb[TCA_NETEM_CORR-1]);
 458                         if (ret)
 459                                 return ret;
 460                 }
 461
 462                 if (tb[TCA_NETEM_DELAY_DIST-1]) {
 463                         ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST-1]);
 464                         if (ret)
 465                                 return ret;
 466                 }
 467
 468                 if (tb[TCA_NETEM_REORDER-1]) {
 469                         ret = get_reorder(sch, tb[TCA_NETEM_REORDER-1]);
 470                         if (ret)
 471                                 return ret;
 472                 }
 473
 474                 if (tb[TCA_NETEM_CORRUPT-1]) {
 475                         ret = get_corrupt(sch, tb[TCA_NETEM_CORRUPT-1]);
 476                         if (ret)
 477                                 return ret;
 478                 }
 479         }
 480
 481         return 0;
 482 }
 483
 484 /*
 485  * Special case version of FIFO queue for use by netem.
 486  * It queues in order based on timestamps in skb's
 487  */
 488 struct fifo_sched_data {
 489         u32 limit;
 490 };
 491
 492 static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
 493 {
 494         struct fifo_sched_data *q = qdisc_priv(sch);
 495         struct sk_buff_head *list = &sch->q;
 496         const struct netem_skb_cb *ncb
 497                 = (const struct netem_skb_cb *)nskb->cb;
 498         struct sk_buff *skb;
 499
 500         if (likely(skb_queue_len(list) < q->limit)) {
 501                 skb_queue_reverse_walk(list, skb) {
 502                         const struct netem_skb_cb *cb
 503                                 = (const struct netem_skb_cb *)skb->cb;
 504
 505                         if (!PSCHED_TLESS(ncb->time_to_send, cb->time_to_send))
 506                                 break;
 507                 }
 508
 509                 __skb_queue_after(list, skb, nskb);
 510
 511                 sch->qstats.backlog += nskb->len;
 512                 sch->bstats.bytes += nskb->len;
 513                 sch->bstats.packets++;
 514
 515                 return NET_XMIT_SUCCESS;
 516         }
 517
 518         return qdisc_drop(nskb, sch);
 519 }
 520
 521 static int tfifo_init(struct Qdisc *sch, struct rtattr *opt)
 522 {
 523         struct fifo_sched_data *q = qdisc_priv(sch);
 524
 525         if (opt) {
 526                 struct tc_fifo_qopt *ctl = RTA_DATA(opt);
 527                 if (RTA_PAYLOAD(opt) < sizeof(*ctl))
 528                         return -EINVAL;
 529
 530                 q->limit = ctl->limit;
 531         } else
 532                 q->limit = max_t(u32, sch->dev->tx_queue_len, 1);
 533
 534         return 0;
 535 }
 536
 537 static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb)
 538 {
 539         struct fifo_sched_data *q = qdisc_priv(sch);
 540         struct tc_fifo_qopt opt = { .limit = q->limit };
 541
 542         RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 543         return skb->len;
 544
 545 rtattr_failure:
 546         return -1;
 547 }
 548
 549 static struct Qdisc_ops tfifo_qdisc_ops = {
 550         .id             =       "tfifo",
 551         .priv_size      =       sizeof(struct fifo_sched_data),
 552         .enqueue        =       tfifo_enqueue,
 553         .dequeue        =       qdisc_dequeue_head,
 554         .requeue        =       qdisc_requeue,
 555         .drop           =       qdisc_queue_drop,
 556         .init           =       tfifo_init,
 557         .reset          =       qdisc_reset_queue,
 558         .change         =       tfifo_init,
 559         .dump           =       tfifo_dump,
 560 };
 561
 562 static int netem_init(struct Qdisc *sch, struct rtattr *opt)
 563 {
 564         struct netem_sched_data *q = qdisc_priv(sch);
 565         int ret;
 566
 567         if (!opt)
 568                 return -EINVAL;
 569
 570         init_timer(&q->timer);
 571         q->timer.function = netem_watchdog;
 572         q->timer.data = (unsigned long) sch;
 573
 574         q->qdisc = qdisc_create_dflt(sch->dev, &tfifo_qdisc_ops,
 575                                      TC_H_MAKE(sch->handle, 1));
 576         if (!q->qdisc) {
 577                 pr_debug("netem: qdisc create failed\n");
 578                 return -ENOMEM;
 579         }
 580
 581         ret = netem_change(sch, opt);
 582         if (ret) {
 583                 pr_debug("netem: change failed\n");
 584                 qdisc_destroy(q->qdisc);
 585         }
 586         return ret;
 587 }
 588
 589 static void netem_destroy(struct Qdisc *sch)
 590 {
 591         struct netem_sched_data *q = qdisc_priv(sch);
 592
 593         del_timer_sync(&q->timer);
 594         qdisc_destroy(q->qdisc);
 595         kfree(q->delay_dist);
 596 }
 597
 598 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
 599 {
 600         const struct netem_sched_data *q = qdisc_priv(sch);
 601         unsigned char    *b = skb->tail;
 602         struct rtattr *rta = (struct rtattr *) b;
 603         struct tc_netem_qopt qopt;
 604         struct tc_netem_corr cor;
 605         struct tc_netem_reorder reorder;
 606         struct tc_netem_corrupt corrupt;
 607
 608         qopt.latency = q->latency;
 609         qopt.jitter = q->jitter;
 610         qopt.limit = q->limit;
 611         qopt.loss = q->loss;
 612         qopt.gap = q->gap;
 613         qopt.duplicate = q->duplicate;
 614         RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
 615
 616         cor.delay_corr = q->delay_cor.rho;
 617         cor.loss_corr = q->loss_cor.rho;
 618         cor.dup_corr = q->dup_cor.rho;
 619         RTA_PUT(skb, TCA_NETEM_CORR, sizeof(cor), &cor);
 620
 621         reorder.probability = q->reorder;
 622         reorder.correlation = q->reorder_cor.rho;
 623         RTA_PUT(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder);
 624
 625         corrupt.probability = q->corrupt;
 626         corrupt.correlation = q->corrupt_cor.rho;
 627         RTA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);
 628
 629         rta->rta_len = skb->tail - b;
 630
 631         return skb->len;
 632
 633 rtattr_failure:
 634         skb_trim(skb, b - skb->data);
 635         return -1;
 636 }
 637
 638 static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
 639                           struct sk_buff *skb, struct tcmsg *tcm)
 640 {
 641         struct netem_sched_data *q = qdisc_priv(sch);
 642
 643         if (cl != 1)    /* only one class */
 644                 return -ENOENT;
 645
 646         tcm->tcm_handle |= TC_H_MIN(1);
 647         tcm->tcm_info = q->qdisc->handle;
 648
 649         return 0;
 650 }
 651
 652 static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 653                      struct Qdisc **old)
 654 {
 655         struct netem_sched_data *q = qdisc_priv(sch);
 656
 657         if (new == NULL)
 658                 new = &noop_qdisc;
 659
 660         sch_tree_lock(sch);
 661         *old = xchg(&q->qdisc, new);
 662         qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
 663         qdisc_reset(*old);
 664         sch_tree_unlock(sch);
 665
 666         return 0;
 667 }
 668
 669 static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
 670 {
 671         struct netem_sched_data *q = qdisc_priv(sch);
 672         return q->qdisc;
 673 }
 674
 675 static unsigned long netem_get(struct Qdisc *sch, u32 classid)
 676 {
 677         return 1;
 678 }
 679
 680 static void netem_put(struct Qdisc *sch, unsigned long arg)
 681 {
 682 }
 683
 684 static int netem_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 685                             struct rtattr **tca, unsigned long *arg)
 686 {
 687         return -ENOSYS;
 688 }
 689
 690 static int netem_delete(struct Qdisc *sch, unsigned long arg)
 691 {
 692         return -ENOSYS;
 693 }
 694
 695 static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 696 {
 697         if (!walker->stop) {
 698                 if (walker->count >= walker->skip)
 699                         if (walker->fn(sch, 1, walker) < 0) {
 700                                 walker->stop = 1;
 701                                 return;
 702                         }
 703                 walker->count++;
 704         }
 705 }
 706
 707 static struct tcf_proto **netem_find_tcf(struct Qdisc *sch, unsigned long cl)
 708 {
 709         return NULL;
 710 }
 711
 712 static struct Qdisc_class_ops netem_class_ops = {
 713         .graft          =       netem_graft,
 714         .leaf           =       netem_leaf,
 715         .get            =       netem_get,
 716         .put            =       netem_put,
 717         .change         =       netem_change_class,
 718         .delete         =       netem_delete,
 719         .walk           =       netem_walk,
 720         .tcf_chain      =       netem_find_tcf,
 721         .dump           =       netem_dump_class,
 722 };
 723
 724 static struct Qdisc_ops netem_qdisc_ops = {
 725         .id             =       "netem",
 726         .cl_ops         =       &netem_class_ops,
 727         .priv_size      =       sizeof(struct netem_sched_data),
 728         .enqueue        =       netem_enqueue,
 729         .dequeue        =       netem_dequeue,
 730         .requeue        =       netem_requeue,
 731         .drop           =       netem_drop,
 732         .init           =       netem_init,
 733         .reset          =       netem_reset,
 734         .destroy        =       netem_destroy,
 735         .change         =       netem_change,
 736         .dump           =       netem_dump,
 737         .owner          =       THIS_MODULE,
 738 };
 739
 740
 741 static int __init netem_module_init(void)
 742 {
 743         pr_info("netem: version " VERSION "\n");
 744         return register_qdisc(&netem_qdisc_ops);
 745 }
 746 static void __exit netem_module_exit(void)
 747 {
 748         unregister_qdisc(&netem_qdisc_ops);
 749 }
 750 module_init(netem_module_init)
 751 module_exit(netem_module_exit)
 752 MODULE_LICENSE("GPL");