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pkt_sched: Use qdisc->ops->peek() instead of ->dequeue() & ->requeue()
[linux-2.6.git] / net / sched / sch_netem.c
blob74fbdb52baedae504bf09d23a266e1abde884260
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->ops->peek(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 skb = q->qdisc->dequeue(q->qdisc);
294 if (!skb)
295 return NULL;
296
297 pr_debug("netem_dequeue: return skb=%p\n", skb);
298 sch->q.qlen--;
299 return skb;
300 }
301
302 qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
303 }
304
305 return NULL;
306 }
307
308 static void netem_reset(struct Qdisc *sch)
309 {
310 struct netem_sched_data *q = qdisc_priv(sch);
311
312 qdisc_reset(q->qdisc);
313 sch->q.qlen = 0;
314 qdisc_watchdog_cancel(&q->watchdog);
315 }
316
317 /*
318 * Distribution data is a variable size payload containing
319 * signed 16 bit values.
320 */
321 static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
322 {
323 struct netem_sched_data *q = qdisc_priv(sch);
324 unsigned long n = nla_len(attr)/sizeof(__s16);
325 const __s16 *data = nla_data(attr);
326 spinlock_t *root_lock;
327 struct disttable *d;
328 int i;
329
330 if (n > 65536)
331 return -EINVAL;
332
333 d = kmalloc(sizeof(*d) + n*sizeof(d->table[0]), GFP_KERNEL);
334 if (!d)
335 return -ENOMEM;
336
337 d->size = n;
338 for (i = 0; i < n; i++)
339 d->table[i] = data[i];
340
341 root_lock = qdisc_root_sleeping_lock(sch);
342
343 spin_lock_bh(root_lock);
344 d = xchg(&q->delay_dist, d);
345 spin_unlock_bh(root_lock);
346
347 kfree(d);
348 return 0;
349 }
350
351 static int get_correlation(struct Qdisc *sch, const struct nlattr *attr)
352 {
353 struct netem_sched_data *q = qdisc_priv(sch);
354 const struct tc_netem_corr *c = nla_data(attr);
355
356 init_crandom(&q->delay_cor, c->delay_corr);
357 init_crandom(&q->loss_cor, c->loss_corr);
358 init_crandom(&q->dup_cor, c->dup_corr);
359 return 0;
360 }
361
362 static int get_reorder(struct Qdisc *sch, const struct nlattr *attr)
363 {
364 struct netem_sched_data *q = qdisc_priv(sch);
365 const struct tc_netem_reorder *r = nla_data(attr);
366
367 q->reorder = r->probability;
368 init_crandom(&q->reorder_cor, r->correlation);
369 return 0;
370 }
371
372 static int get_corrupt(struct Qdisc *sch, const struct nlattr *attr)
373 {
374 struct netem_sched_data *q = qdisc_priv(sch);
375 const struct tc_netem_corrupt *r = nla_data(attr);
376
377 q->corrupt = r->probability;
378 init_crandom(&q->corrupt_cor, r->correlation);
379 return 0;
380 }
381
382 static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
383 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
384 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
385 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
386 };
387
388 static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
389 const struct nla_policy *policy, int len)
390 {
391 int nested_len = nla_len(nla) - NLA_ALIGN(len);
392
393 if (nested_len < 0)
394 return -EINVAL;
395 if (nested_len >= nla_attr_size(0))
396 return nla_parse(tb, maxtype, nla_data(nla) + NLA_ALIGN(len),
397 nested_len, policy);
398 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
399 return 0;
400 }
401
402 /* Parse netlink message to set options */
403 static int netem_change(struct Qdisc *sch, struct nlattr *opt)
404 {
405 struct netem_sched_data *q = qdisc_priv(sch);
406 struct nlattr *tb[TCA_NETEM_MAX + 1];
407 struct tc_netem_qopt *qopt;
408 int ret;
409
410 if (opt == NULL)
411 return -EINVAL;
412
413 qopt = nla_data(opt);
414 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
415 if (ret < 0)
416 return ret;
417
418 ret = fifo_set_limit(q->qdisc, qopt->limit);
419 if (ret) {
420 pr_debug("netem: can't set fifo limit\n");
421 return ret;
422 }
423
424 q->latency = qopt->latency;
425 q->jitter = qopt->jitter;
426 q->limit = qopt->limit;
427 q->gap = qopt->gap;
428 q->counter = 0;
429 q->loss = qopt->loss;
430 q->duplicate = qopt->duplicate;
431
432 /* for compatibility with earlier versions.
433 * if gap is set, need to assume 100% probability
434 */
435 if (q->gap)
436 q->reorder = ~0;
437
438 if (tb[TCA_NETEM_CORR]) {
439 ret = get_correlation(sch, tb[TCA_NETEM_CORR]);
440 if (ret)
441 return ret;
442 }
443
444 if (tb[TCA_NETEM_DELAY_DIST]) {
445 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
446 if (ret)
447 return ret;
448 }
449
450 if (tb[TCA_NETEM_REORDER]) {
451 ret = get_reorder(sch, tb[TCA_NETEM_REORDER]);
452 if (ret)
453 return ret;
454 }
455
456 if (tb[TCA_NETEM_CORRUPT]) {
457 ret = get_corrupt(sch, tb[TCA_NETEM_CORRUPT]);
458 if (ret)
459 return ret;
460 }
461
462 return 0;
463 }
464
465 /*
466 * Special case version of FIFO queue for use by netem.
467 * It queues in order based on timestamps in skb's
468 */
469 struct fifo_sched_data {
470 u32 limit;
471 psched_time_t oldest;
472 };
473
474 static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
475 {
476 struct fifo_sched_data *q = qdisc_priv(sch);
477 struct sk_buff_head *list = &sch->q;
478 psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
479 struct sk_buff *skb;
480
481 if (likely(skb_queue_len(list) < q->limit)) {
482 /* Optimize for add at tail */
483 if (likely(skb_queue_empty(list) || tnext >= q->oldest)) {
484 q->oldest = tnext;
485 return qdisc_enqueue_tail(nskb, sch);
486 }
487
488 skb_queue_reverse_walk(list, skb) {
489 const struct netem_skb_cb *cb = netem_skb_cb(skb);
490
491 if (tnext >= cb->time_to_send)
492 break;
493 }
494
495 __skb_queue_after(list, skb, nskb);
496
497 sch->qstats.backlog += qdisc_pkt_len(nskb);
498 sch->bstats.bytes += qdisc_pkt_len(nskb);
499 sch->bstats.packets++;
500
501 return NET_XMIT_SUCCESS;
502 }
503
504 return qdisc_reshape_fail(nskb, sch);
505 }
506
507 static int tfifo_init(struct Qdisc *sch, struct nlattr *opt)
508 {
509 struct fifo_sched_data *q = qdisc_priv(sch);
510
511 if (opt) {
512 struct tc_fifo_qopt *ctl = nla_data(opt);
513 if (nla_len(opt) < sizeof(*ctl))
514 return -EINVAL;
515
516 q->limit = ctl->limit;
517 } else
518 q->limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
519
520 q->oldest = PSCHED_PASTPERFECT;
521 return 0;
522 }
523
524 static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb)
525 {
526 struct fifo_sched_data *q = qdisc_priv(sch);
527 struct tc_fifo_qopt opt = { .limit = q->limit };
528
529 NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
530 return skb->len;
531
532 nla_put_failure:
533 return -1;
534 }
535
536 static struct Qdisc_ops tfifo_qdisc_ops __read_mostly = {
537 .id = "tfifo",
538 .priv_size = sizeof(struct fifo_sched_data),
539 .enqueue = tfifo_enqueue,
540 .dequeue = qdisc_dequeue_head,
541 .peek = qdisc_peek_head,
542 .requeue = qdisc_requeue,
543 .drop = qdisc_queue_drop,
544 .init = tfifo_init,
545 .reset = qdisc_reset_queue,
546 .change = tfifo_init,
547 .dump = tfifo_dump,
548 };
549
550 static int netem_init(struct Qdisc *sch, struct nlattr *opt)
551 {
552 struct netem_sched_data *q = qdisc_priv(sch);
553 int ret;
554
555 if (!opt)
556 return -EINVAL;
557
558 qdisc_watchdog_init(&q->watchdog, sch);
559
560 q->qdisc = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
561 &tfifo_qdisc_ops,
562 TC_H_MAKE(sch->handle, 1));
563 if (!q->qdisc) {
564 pr_debug("netem: qdisc create failed\n");
565 return -ENOMEM;
566 }
567
568 ret = netem_change(sch, opt);
569 if (ret) {
570 pr_debug("netem: change failed\n");
571 qdisc_destroy(q->qdisc);
572 }
573 return ret;
574 }
575
576 static void netem_destroy(struct Qdisc *sch)
577 {
578 struct netem_sched_data *q = qdisc_priv(sch);
579
580 qdisc_watchdog_cancel(&q->watchdog);
581 qdisc_destroy(q->qdisc);
582 kfree(q->delay_dist);
583 }
584
585 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
586 {
587 const struct netem_sched_data *q = qdisc_priv(sch);
588 unsigned char *b = skb_tail_pointer(skb);
589 struct nlattr *nla = (struct nlattr *) b;
590 struct tc_netem_qopt qopt;
591 struct tc_netem_corr cor;
592 struct tc_netem_reorder reorder;
593 struct tc_netem_corrupt corrupt;
594
595 qopt.latency = q->latency;
596 qopt.jitter = q->jitter;
597 qopt.limit = q->limit;
598 qopt.loss = q->loss;
599 qopt.gap = q->gap;
600 qopt.duplicate = q->duplicate;
601 NLA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
602
603 cor.delay_corr = q->delay_cor.rho;
604 cor.loss_corr = q->loss_cor.rho;
605 cor.dup_corr = q->dup_cor.rho;
606 NLA_PUT(skb, TCA_NETEM_CORR, sizeof(cor), &cor);
607
608 reorder.probability = q->reorder;
609 reorder.correlation = q->reorder_cor.rho;
610 NLA_PUT(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder);
611
612 corrupt.probability = q->corrupt;
613 corrupt.correlation = q->corrupt_cor.rho;
614 NLA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);
615
616 nla->nla_len = skb_tail_pointer(skb) - b;
617
618 return skb->len;
619
620 nla_put_failure:
621 nlmsg_trim(skb, b);
622 return -1;
623 }
624
625 static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
626 struct sk_buff *skb, struct tcmsg *tcm)
627 {
628 struct netem_sched_data *q = qdisc_priv(sch);
629
630 if (cl != 1) /* only one class */
631 return -ENOENT;
632
633 tcm->tcm_handle |= TC_H_MIN(1);
634 tcm->tcm_info = q->qdisc->handle;
635
636 return 0;
637 }
638
639 static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
640 struct Qdisc **old)
641 {
642 struct netem_sched_data *q = qdisc_priv(sch);
643
644 if (new == NULL)
645 new = &noop_qdisc;
646
647 sch_tree_lock(sch);
648 *old = xchg(&q->qdisc, new);
649 qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
650 qdisc_reset(*old);
651 sch_tree_unlock(sch);
652
653 return 0;
654 }
655
656 static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
657 {
658 struct netem_sched_data *q = qdisc_priv(sch);
659 return q->qdisc;
660 }
661
662 static unsigned long netem_get(struct Qdisc *sch, u32 classid)
663 {
664 return 1;
665 }
666
667 static void netem_put(struct Qdisc *sch, unsigned long arg)
668 {
669 }
670
671 static int netem_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
672 struct nlattr **tca, unsigned long *arg)
673 {
674 return -ENOSYS;
675 }
676
677 static int netem_delete(struct Qdisc *sch, unsigned long arg)
678 {
679 return -ENOSYS;
680 }
681
682 static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
683 {
684 if (!walker->stop) {
685 if (walker->count >= walker->skip)
686 if (walker->fn(sch, 1, walker) < 0) {
687 walker->stop = 1;
688 return;
689 }
690 walker->count++;
691 }
692 }
693
694 static struct tcf_proto **netem_find_tcf(struct Qdisc *sch, unsigned long cl)
695 {
696 return NULL;
697 }
698
699 static const struct Qdisc_class_ops netem_class_ops = {
700 .graft = netem_graft,
701 .leaf = netem_leaf,
702 .get = netem_get,
703 .put = netem_put,
704 .change = netem_change_class,
705 .delete = netem_delete,
706 .walk = netem_walk,
707 .tcf_chain = netem_find_tcf,
708 .dump = netem_dump_class,
709 };
710
711 static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
712 .id = "netem",
713 .cl_ops = &netem_class_ops,
714 .priv_size = sizeof(struct netem_sched_data),
715 .enqueue = netem_enqueue,
716 .dequeue = netem_dequeue,
717 .requeue = netem_requeue,
718 .drop = netem_drop,
719 .init = netem_init,
720 .reset = netem_reset,
721 .destroy = netem_destroy,
722 .change = netem_change,
723 .dump = netem_dump,
724 .owner = THIS_MODULE,
725 };
726
727
728 static int __init netem_module_init(void)
729 {
730 pr_info("netem: version " VERSION "\n");
731 return register_qdisc(&netem_qdisc_ops);
732 }
733 static void __exit netem_module_exit(void)
734 {
735 unregister_qdisc(&netem_qdisc_ops);
736 }
737 module_init(netem_module_init)
738 module_exit(netem_module_exit)
739 MODULE_LICENSE("GPL");
Linus' kernel tree