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, or (at your option) any later version. 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 struct netem_skb_cb *cb = (struct netem_skb_cb *)skb->cb; 152 struct sk_buff *skb2; 153 int ret; 154 int count = 1; 155 156 pr_debug("netem_enqueue skb=%p\n", skb); 157 158 /* Random duplication */ 159 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor)) 160 ++count; 161 162 /* Random packet drop 0 => none, ~0 => all */ 163 if (q->loss && q->loss >= get_crandom(&q->loss_cor)) 164 --count; 165 166 if (count == 0) { 167 sch->qstats.drops++; 168 kfree_skb(skb); 169 return NET_XMIT_BYPASS; 170 } 171 172 /* 173 * If we need to duplicate packet, then re-insert at top of the 174 * qdisc tree, since parent queuer expects that only one 175 * skb will be queued. 176 */ 177 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) { 178 struct Qdisc *rootq = sch->dev->qdisc; 179 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */ 180 q->duplicate = 0; 181 182 rootq->enqueue(skb2, rootq); 183 q->duplicate = dupsave; 184 } 185 186 /* 187 * Randomized packet corruption. 188 * Make copy if needed since we are modifying 189 * If packet is going to be hardware checksummed, then 190 * do it now in software before we mangle it. 191 */ 192 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) { 193 if (!(skb = skb_unshare(skb, GFP_ATOMIC)) 194 || (skb->ip_summed == CHECKSUM_HW 195 && skb_checksum_help(skb, 0))) { 196 sch->qstats.drops++; 197 return NET_XMIT_DROP; 198 } 199 200 skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8); 201 } 202 203 if (q->gap == 0 /* not doing reordering */ 204 || q->counter < q->gap /* inside last reordering gap */ 205 || q->reorder < get_crandom(&q->reorder_cor)) { 206 psched_time_t now; 207 psched_tdiff_t delay; 208 209 delay = tabledist(q->latency, q->jitter, 210 &q->delay_cor, q->delay_dist); 211 212 PSCHED_GET_TIME(now); 213 PSCHED_TADD2(now, delay, cb->time_to_send); 214 ++q->counter; 215 ret = q->qdisc->enqueue(skb, q->qdisc); 216 } else { 217 /* 218 * Do re-ordering by putting one out of N packets at the front 219 * of the queue. 220 */ 221 PSCHED_GET_TIME(cb->time_to_send); 222 q->counter = 0; 223 ret = q->qdisc->ops->requeue(skb, q->qdisc); 224 } 225 226 if (likely(ret == NET_XMIT_SUCCESS)) { 227 sch->q.qlen++; 228 sch->bstats.bytes += skb->len; 229 sch->bstats.packets++; 230 } else 231 sch->qstats.drops++; 232 233 pr_debug("netem: enqueue ret %d\n", ret); 234 return ret; 235 } 236 237 /* Requeue packets but don't change time stamp */ 238 static int netem_requeue(struct sk_buff *skb, struct Qdisc *sch) 239 { 240 struct netem_sched_data *q = qdisc_priv(sch); 241 int ret; 242 243 if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) { 244 sch->q.qlen++; 245 sch->qstats.requeues++; 246 } 247 248 return ret; 249 } 250 251 static unsigned int netem_drop(struct Qdisc* sch) 252 { 253 struct netem_sched_data *q = qdisc_priv(sch); 254 unsigned int len = 0; 255 256 if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) { 257 sch->q.qlen--; 258 sch->qstats.drops++; 259 } 260 return len; 261 } 262 263 static struct sk_buff *netem_dequeue(struct Qdisc *sch) 264 { 265 struct netem_sched_data *q = qdisc_priv(sch); 266 struct sk_buff *skb; 267 268 skb = q->qdisc->dequeue(q->qdisc); 269 if (skb) { 270 const struct netem_skb_cb *cb 271 = (const struct netem_skb_cb *)skb->cb; 272 psched_time_t now; 273 274 /* if more time remaining? */ 275 PSCHED_GET_TIME(now); 276 277 if (PSCHED_TLESS(cb->time_to_send, now)) { 278 pr_debug("netem_dequeue: return skb=%p\n", skb); 279 sch->q.qlen--; 280 sch->flags &= ~TCQ_F_THROTTLED; 281 return skb; 282 } else { 283 psched_tdiff_t delay = PSCHED_TDIFF(cb->time_to_send, now); 284 285 if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) { 286 sch->qstats.drops++; 287 288 /* After this qlen is confused */ 289 printk(KERN_ERR "netem: queue discpline %s could not requeue\n", 290 q->qdisc->ops->id); 291 292 sch->q.qlen--; 293 } 294 295 mod_timer(&q->timer, jiffies + PSCHED_US2JIFFIE(delay)); 296 sch->flags |= TCQ_F_THROTTLED; 297 } 298 } 299 300 return NULL; 301 } 302 303 static void netem_watchdog(unsigned long arg) 304 { 305 struct Qdisc *sch = (struct Qdisc *)arg; 306 307 pr_debug("netem_watchdog qlen=%d\n", sch->q.qlen); 308 sch->flags &= ~TCQ_F_THROTTLED; 309 netif_schedule(sch->dev); 310 } 311 312 static void netem_reset(struct Qdisc *sch) 313 { 314 struct netem_sched_data *q = qdisc_priv(sch); 315 316 qdisc_reset(q->qdisc); 317 sch->q.qlen = 0; 318 sch->flags &= ~TCQ_F_THROTTLED; 319 del_timer_sync(&q->timer); 320 } 321 322 /* Pass size change message down to embedded FIFO */ 323 static int set_fifo_limit(struct Qdisc *q, int limit) 324 { 325 struct rtattr *rta; 326 int ret = -ENOMEM; 327 328 /* Hack to avoid sending change message to non-FIFO */ 329 if (strncmp(q->ops->id + 1, "fifo", 4) != 0) 330 return 0; 331 332 rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL); 333 if (rta) { 334 rta->rta_type = RTM_NEWQDISC; 335 rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt)); 336 ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit; 337 338 ret = q->ops->change(q, rta); 339 kfree(rta); 340 } 341 return ret; 342 } 343 344 /* 345 * Distribution data is a variable size payload containing 346 * signed 16 bit values. 347 */ 348 static int get_dist_table(struct Qdisc *sch, const struct rtattr *attr) 349 { 350 struct netem_sched_data *q = qdisc_priv(sch); 351 unsigned long n = RTA_PAYLOAD(attr)/sizeof(__s16); 352 const __s16 *data = RTA_DATA(attr); 353 struct disttable *d; 354 int i; 355 356 if (n > 65536) 357 return -EINVAL; 358 359 d = kmalloc(sizeof(*d) + n*sizeof(d->table[0]), GFP_KERNEL); 360 if (!d) 361 return -ENOMEM; 362 363 d->size = n; 364 for (i = 0; i < n; i++) 365 d->table[i] = data[i]; 366 367 spin_lock_bh(&sch->dev->queue_lock); 368 d = xchg(&q->delay_dist, d); 369 spin_unlock_bh(&sch->dev->queue_lock); 370 371 kfree(d); 372 return 0; 373 } 374 375 static int get_correlation(struct Qdisc *sch, const struct rtattr *attr) 376 { 377 struct netem_sched_data *q = qdisc_priv(sch); 378 const struct tc_netem_corr *c = RTA_DATA(attr); 379 380 if (RTA_PAYLOAD(attr) != sizeof(*c)) 381 return -EINVAL; 382 383 init_crandom(&q->delay_cor, c->delay_corr); 384 init_crandom(&q->loss_cor, c->loss_corr); 385 init_crandom(&q->dup_cor, c->dup_corr); 386 return 0; 387 } 388 389 static int get_reorder(struct Qdisc *sch, const struct rtattr *attr) 390 { 391 struct netem_sched_data *q = qdisc_priv(sch); 392 const struct tc_netem_reorder *r = RTA_DATA(attr); 393 394 if (RTA_PAYLOAD(attr) != sizeof(*r)) 395 return -EINVAL; 396 397 q->reorder = r->probability; 398 init_crandom(&q->reorder_cor, r->correlation); 399 return 0; 400 } 401 402 static int get_corrupt(struct Qdisc *sch, const struct rtattr *attr) 403 { 404 struct netem_sched_data *q = qdisc_priv(sch); 405 const struct tc_netem_corrupt *r = RTA_DATA(attr); 406 407 if (RTA_PAYLOAD(attr) != sizeof(*r)) 408 return -EINVAL; 409 410 q->corrupt = r->probability; 411 init_crandom(&q->corrupt_cor, r->correlation); 412 return 0; 413 } 414 415 /* Parse netlink message to set options */ 416 static int netem_change(struct Qdisc *sch, struct rtattr *opt) 417 { 418 struct netem_sched_data *q = qdisc_priv(sch); 419 struct tc_netem_qopt *qopt; 420 int ret; 421 422 if (opt == NULL || RTA_PAYLOAD(opt) < sizeof(*qopt)) 423 return -EINVAL; 424 425 qopt = RTA_DATA(opt); 426 ret = set_fifo_limit(q->qdisc, qopt->limit); 427 if (ret) { 428 pr_debug("netem: can't set fifo limit\n"); 429 return ret; 430 } 431 432 q->latency = qopt->latency; 433 q->jitter = qopt->jitter; 434 q->limit = qopt->limit; 435 q->gap = qopt->gap; 436 q->counter = 0; 437 q->loss = qopt->loss; 438 q->duplicate = qopt->duplicate; 439 440 /* for compatiablity with earlier versions. 441 * if gap is set, need to assume 100% probablity 442 */ 443 q->reorder = ~0; 444 445 /* Handle nested options after initial queue options. 446 * Should have put all options in nested format but too late now. 447 */ 448 if (RTA_PAYLOAD(opt) > sizeof(*qopt)) { 449 struct rtattr *tb[TCA_NETEM_MAX]; 450 if (rtattr_parse(tb, TCA_NETEM_MAX, 451 RTA_DATA(opt) + sizeof(*qopt), 452 RTA_PAYLOAD(opt) - sizeof(*qopt))) 453 return -EINVAL; 454 455 if (tb[TCA_NETEM_CORR-1]) { 456 ret = get_correlation(sch, tb[TCA_NETEM_CORR-1]); 457 if (ret) 458 return ret; 459 } 460 461 if (tb[TCA_NETEM_DELAY_DIST-1]) { 462 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST-1]); 463 if (ret) 464 return ret; 465 } 466 467 if (tb[TCA_NETEM_REORDER-1]) { 468 ret = get_reorder(sch, tb[TCA_NETEM_REORDER-1]); 469 if (ret) 470 return ret; 471 } 472 473 if (tb[TCA_NETEM_CORRUPT-1]) { 474 ret = get_corrupt(sch, tb[TCA_NETEM_CORRUPT-1]); 475 if (ret) 476 return ret; 477 } 478 } 479 480 return 0; 481 } 482 483 /* 484 * Special case version of FIFO queue for use by netem. 485 * It queues in order based on timestamps in skb's 486 */ 487 struct fifo_sched_data { 488 u32 limit; 489 }; 490 491 static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch) 492 { 493 struct fifo_sched_data *q = qdisc_priv(sch); 494 struct sk_buff_head *list = &sch->q; 495 const struct netem_skb_cb *ncb 496 = (const struct netem_skb_cb *)nskb->cb; 497 struct sk_buff *skb; 498 499 if (likely(skb_queue_len(list) < q->limit)) { 500 skb_queue_reverse_walk(list, skb) { 501 const struct netem_skb_cb *cb 502 = (const struct netem_skb_cb *)skb->cb; 503 504 if (!PSCHED_TLESS(ncb->time_to_send, cb->time_to_send)) 505 break; 506 } 507 508 __skb_queue_after(list, skb, nskb); 509 510 sch->qstats.backlog += nskb->len; 511 sch->bstats.bytes += nskb->len; 512 sch->bstats.packets++; 513 514 return NET_XMIT_SUCCESS; 515 } 516 517 return qdisc_drop(nskb, sch); 518 } 519 520 static int tfifo_init(struct Qdisc *sch, struct rtattr *opt) 521 { 522 struct fifo_sched_data *q = qdisc_priv(sch); 523 524 if (opt) { 525 struct tc_fifo_qopt *ctl = RTA_DATA(opt); 526 if (RTA_PAYLOAD(opt) < sizeof(*ctl)) 527 return -EINVAL; 528 529 q->limit = ctl->limit; 530 } else 531 q->limit = max_t(u32, sch->dev->tx_queue_len, 1); 532 533 return 0; 534 } 535 536 static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb) 537 { 538 struct fifo_sched_data *q = qdisc_priv(sch); 539 struct tc_fifo_qopt opt = { .limit = q->limit }; 540 541 RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); 542 return skb->len; 543 544 rtattr_failure: 545 return -1; 546 } 547 548 static struct Qdisc_ops tfifo_qdisc_ops = { 549 .id = "tfifo", 550 .priv_size = sizeof(struct fifo_sched_data), 551 .enqueue = tfifo_enqueue, 552 .dequeue = qdisc_dequeue_head, 553 .requeue = qdisc_requeue, 554 .drop = qdisc_queue_drop, 555 .init = tfifo_init, 556 .reset = qdisc_reset_queue, 557 .change = tfifo_init, 558 .dump = tfifo_dump, 559 }; 560 561 static int netem_init(struct Qdisc *sch, struct rtattr *opt) 562 { 563 struct netem_sched_data *q = qdisc_priv(sch); 564 int ret; 565 566 if (!opt) 567 return -EINVAL; 568 569 init_timer(&q->timer); 570 q->timer.function = netem_watchdog; 571 q->timer.data = (unsigned long) sch; 572 573 q->qdisc = qdisc_create_dflt(sch->dev, &tfifo_qdisc_ops); 574 if (!q->qdisc) { 575 pr_debug("netem: qdisc create failed\n"); 576 return -ENOMEM; 577 } 578 579 ret = netem_change(sch, opt); 580 if (ret) { 581 pr_debug("netem: change failed\n"); 582 qdisc_destroy(q->qdisc); 583 } 584 return ret; 585 } 586 587 static void netem_destroy(struct Qdisc *sch) 588 { 589 struct netem_sched_data *q = qdisc_priv(sch); 590 591 del_timer_sync(&q->timer); 592 qdisc_destroy(q->qdisc); 593 kfree(q->delay_dist); 594 } 595 596 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb) 597 { 598 const struct netem_sched_data *q = qdisc_priv(sch); 599 unsigned char *b = skb->tail; 600 struct rtattr *rta = (struct rtattr *) b; 601 struct tc_netem_qopt qopt; 602 struct tc_netem_corr cor; 603 struct tc_netem_reorder reorder; 604 struct tc_netem_corrupt corrupt; 605 606 qopt.latency = q->latency; 607 qopt.jitter = q->jitter; 608 qopt.limit = q->limit; 609 qopt.loss = q->loss; 610 qopt.gap = q->gap; 611 qopt.duplicate = q->duplicate; 612 RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt); 613 614 cor.delay_corr = q->delay_cor.rho; 615 cor.loss_corr = q->loss_cor.rho; 616 cor.dup_corr = q->dup_cor.rho; 617 RTA_PUT(skb, TCA_NETEM_CORR, sizeof(cor), &cor); 618 619 reorder.probability = q->reorder; 620 reorder.correlation = q->reorder_cor.rho; 621 RTA_PUT(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder); 622 623 corrupt.probability = q->corrupt; 624 corrupt.correlation = q->corrupt_cor.rho; 625 RTA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt); 626 627 rta->rta_len = skb->tail - b; 628 629 return skb->len; 630 631 rtattr_failure: 632 skb_trim(skb, b - skb->data); 633 return -1; 634 } 635 636 static int netem_dump_class(struct Qdisc *sch, unsigned long cl, 637 struct sk_buff *skb, struct tcmsg *tcm) 638 { 639 struct netem_sched_data *q = qdisc_priv(sch); 640 641 if (cl != 1) /* only one class */ 642 return -ENOENT; 643 644 tcm->tcm_handle |= TC_H_MIN(1); 645 tcm->tcm_info = q->qdisc->handle; 646 647 return 0; 648 } 649 650 static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 651 struct Qdisc **old) 652 { 653 struct netem_sched_data *q = qdisc_priv(sch); 654 655 if (new == NULL) 656 new = &noop_qdisc; 657 658 sch_tree_lock(sch); 659 *old = xchg(&q->qdisc, new); 660 qdisc_reset(*old); 661 sch->q.qlen = 0; 662 sch_tree_unlock(sch); 663 664 return 0; 665 } 666 667 static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg) 668 { 669 struct netem_sched_data *q = qdisc_priv(sch); 670 return q->qdisc; 671 } 672 673 static unsigned long netem_get(struct Qdisc *sch, u32 classid) 674 { 675 return 1; 676 } 677 678 static void netem_put(struct Qdisc *sch, unsigned long arg) 679 { 680 } 681 682 static int netem_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 683 struct rtattr **tca, unsigned long *arg) 684 { 685 return -ENOSYS; 686 } 687 688 static int netem_delete(struct Qdisc *sch, unsigned long arg) 689 { 690 return -ENOSYS; 691 } 692 693 static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker) 694 { 695 if (!walker->stop) { 696 if (walker->count >= walker->skip) 697 if (walker->fn(sch, 1, walker) < 0) { 698 walker->stop = 1; 699 return; 700 } 701 walker->count++; 702 } 703 } 704 705 static struct tcf_proto **netem_find_tcf(struct Qdisc *sch, unsigned long cl) 706 { 707 return NULL; 708 } 709 710 static struct Qdisc_class_ops netem_class_ops = { 711 .graft = netem_graft, 712 .leaf = netem_leaf, 713 .get = netem_get, 714 .put = netem_put, 715 .change = netem_change_class, 716 .delete = netem_delete, 717 .walk = netem_walk, 718 .tcf_chain = netem_find_tcf, 719 .dump = netem_dump_class, 720 }; 721 722 static struct Qdisc_ops netem_qdisc_ops = { 723 .id = "netem", 724 .cl_ops = &netem_class_ops, 725 .priv_size = sizeof(struct netem_sched_data), 726 .enqueue = netem_enqueue, 727 .dequeue = netem_dequeue, 728 .requeue = netem_requeue, 729 .drop = netem_drop, 730 .init = netem_init, 731 .reset = netem_reset, 732 .destroy = netem_destroy, 733 .change = netem_change, 734 .dump = netem_dump, 735 .owner = THIS_MODULE, 736 }; 737 738 739 static int __init netem_module_init(void) 740 { 741 pr_info("netem: version " VERSION "\n"); 742 return register_qdisc(&netem_qdisc_ops); 743 } 744 static void __exit netem_module_exit(void) 745 { 746 unregister_qdisc(&netem_qdisc_ops); 747 } 748 module_init(netem_module_init) 749 module_exit(netem_module_exit) 750 MODULE_LICENSE("GPL"); 751