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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/mm.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/types.h>
20#include <linux/kernel.h>
21#include <linux/errno.h>
22#include <linux/skbuff.h>
23#include <linux/vmalloc.h>
24#include <linux/rtnetlink.h>
25#include <linux/reciprocal_div.h>
26
27#include <net/netlink.h>
28#include <net/pkt_sched.h>
29#include <net/inet_ecn.h>
30
31#define VERSION "1.3"
32
33/* Network Emulation Queuing algorithm.
34 ====================================
35
36 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
37 Network Emulation Tool
38 [2] Luigi Rizzo, DummyNet for FreeBSD
39
40 ----------------------------------------------------------------
41
42 This started out as a simple way to delay outgoing packets to
43 test TCP but has grown to include most of the functionality
44 of a full blown network emulator like NISTnet. It can delay
45 packets and add random jitter (and correlation). The random
46 distribution can be loaded from a table as well to provide
47 normal, Pareto, or experimental curves. Packet loss,
48 duplication, and reordering can also be emulated.
49
50 This qdisc does not do classification that can be handled in
51 layering other disciplines. It does not need to do bandwidth
52 control either since that can be handled by using token
53 bucket or other rate control.
54
55 Correlated Loss Generator models
56
57 Added generation of correlated loss according to the
58 "Gilbert-Elliot" model, a 4-state markov model.
59
60 References:
61 [1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG
62 [2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
63 and intuitive loss model for packet networks and its implementation
64 in the Netem module in the Linux kernel", available in [1]
65
66 Authors: Stefano Salsano <stefano.salsano at uniroma2.it
67 Fabio Ludovici <fabio.ludovici at yahoo.it>
68*/
69
70struct netem_sched_data {
71 /* internal t(ime)fifo qdisc uses sch->q and sch->limit */
72
73 /* optional qdisc for classful handling (NULL at netem init) */
74 struct Qdisc *qdisc;
75
76 struct qdisc_watchdog watchdog;
77
78 psched_tdiff_t latency;
79 psched_tdiff_t jitter;
80
81 u32 loss;
82 u32 ecn;
83 u32 limit;
84 u32 counter;
85 u32 gap;
86 u32 duplicate;
87 u32 reorder;
88 u32 corrupt;
89 u32 rate;
90 s32 packet_overhead;
91 u32 cell_size;
92 u32 cell_size_reciprocal;
93 s32 cell_overhead;
94
95 struct crndstate {
96 u32 last;
97 u32 rho;
98 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
99
100 struct disttable {
101 u32 size;
102 s16 table[0];
103 } *delay_dist;
104
105 enum {
106 CLG_RANDOM,
107 CLG_4_STATES,
108 CLG_GILB_ELL,
109 } loss_model;
110
111 /* Correlated Loss Generation models */
112 struct clgstate {
113 /* state of the Markov chain */
114 u8 state;
115
116 /* 4-states and Gilbert-Elliot models */
117 u32 a1; /* p13 for 4-states or p for GE */
118 u32 a2; /* p31 for 4-states or r for GE */
119 u32 a3; /* p32 for 4-states or h for GE */
120 u32 a4; /* p14 for 4-states or 1-k for GE */
121 u32 a5; /* p23 used only in 4-states */
122 } clg;
123
124};
125
126/* Time stamp put into socket buffer control block
127 * Only valid when skbs are in our internal t(ime)fifo queue.
128 */
129struct netem_skb_cb {
130 psched_time_t time_to_send;
131};
132
133static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
134{
135 qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb));
136 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
137}
138
139/* init_crandom - initialize correlated random number generator
140 * Use entropy source for initial seed.
141 */
142static void init_crandom(struct crndstate *state, unsigned long rho)
143{
144 state->rho = rho;
145 state->last = net_random();
146}
147
148/* get_crandom - correlated random number generator
149 * Next number depends on last value.
150 * rho is scaled to avoid floating point.
151 */
152static u32 get_crandom(struct crndstate *state)
153{
154 u64 value, rho;
155 unsigned long answer;
156
157 if (state->rho == 0) /* no correlation */
158 return net_random();
159
160 value = net_random();
161 rho = (u64)state->rho + 1;
162 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
163 state->last = answer;
164 return answer;
165}
166
167/* loss_4state - 4-state model loss generator
168 * Generates losses according to the 4-state Markov chain adopted in
169 * the GI (General and Intuitive) loss model.
170 */
171static bool loss_4state(struct netem_sched_data *q)
172{
173 struct clgstate *clg = &q->clg;
174 u32 rnd = net_random();
175
176 /*
177 * Makes a comparison between rnd and the transition
178 * probabilities outgoing from the current state, then decides the
179 * next state and if the next packet has to be transmitted or lost.
180 * The four states correspond to:
181 * 1 => successfully transmitted packets within a gap period
182 * 4 => isolated losses within a gap period
183 * 3 => lost packets within a burst period
184 * 2 => successfully transmitted packets within a burst period
185 */
186 switch (clg->state) {
187 case 1:
188 if (rnd < clg->a4) {
189 clg->state = 4;
190 return true;
191 } else if (clg->a4 < rnd && rnd < clg->a1) {
192 clg->state = 3;
193 return true;
194 } else if (clg->a1 < rnd)
195 clg->state = 1;
196
197 break;
198 case 2:
199 if (rnd < clg->a5) {
200 clg->state = 3;
201 return true;
202 } else
203 clg->state = 2;
204
205 break;
206 case 3:
207 if (rnd < clg->a3)
208 clg->state = 2;
209 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
210 clg->state = 1;
211 return true;
212 } else if (clg->a2 + clg->a3 < rnd) {
213 clg->state = 3;
214 return true;
215 }
216 break;
217 case 4:
218 clg->state = 1;
219 break;
220 }
221
222 return false;
223}
224
225/* loss_gilb_ell - Gilbert-Elliot model loss generator
226 * Generates losses according to the Gilbert-Elliot loss model or
227 * its special cases (Gilbert or Simple Gilbert)
228 *
229 * Makes a comparison between random number and the transition
230 * probabilities outgoing from the current state, then decides the
231 * next state. A second random number is extracted and the comparison
232 * with the loss probability of the current state decides if the next
233 * packet will be transmitted or lost.
234 */
235static bool loss_gilb_ell(struct netem_sched_data *q)
236{
237 struct clgstate *clg = &q->clg;
238
239 switch (clg->state) {
240 case 1:
241 if (net_random() < clg->a1)
242 clg->state = 2;
243 if (net_random() < clg->a4)
244 return true;
245 case 2:
246 if (net_random() < clg->a2)
247 clg->state = 1;
248 if (clg->a3 > net_random())
249 return true;
250 }
251
252 return false;
253}
254
255static bool loss_event(struct netem_sched_data *q)
256{
257 switch (q->loss_model) {
258 case CLG_RANDOM:
259 /* Random packet drop 0 => none, ~0 => all */
260 return q->loss && q->loss >= get_crandom(&q->loss_cor);
261
262 case CLG_4_STATES:
263 /* 4state loss model algorithm (used also for GI model)
264 * Extracts a value from the markov 4 state loss generator,
265 * if it is 1 drops a packet and if needed writes the event in
266 * the kernel logs
267 */
268 return loss_4state(q);
269
270 case CLG_GILB_ELL:
271 /* Gilbert-Elliot loss model algorithm
272 * Extracts a value from the Gilbert-Elliot loss generator,
273 * if it is 1 drops a packet and if needed writes the event in
274 * the kernel logs
275 */
276 return loss_gilb_ell(q);
277 }
278
279 return false; /* not reached */
280}
281
282
283/* tabledist - return a pseudo-randomly distributed value with mean mu and
284 * std deviation sigma. Uses table lookup to approximate the desired
285 * distribution, and a uniformly-distributed pseudo-random source.
286 */
287static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
288 struct crndstate *state,
289 const struct disttable *dist)
290{
291 psched_tdiff_t x;
292 long t;
293 u32 rnd;
294
295 if (sigma == 0)
296 return mu;
297
298 rnd = get_crandom(state);
299
300 /* default uniform distribution */
301 if (dist == NULL)
302 return (rnd % (2*sigma)) - sigma + mu;
303
304 t = dist->table[rnd % dist->size];
305 x = (sigma % NETEM_DIST_SCALE) * t;
306 if (x >= 0)
307 x += NETEM_DIST_SCALE/2;
308 else
309 x -= NETEM_DIST_SCALE/2;
310
311 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
312}
313
314static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sched_data *q)
315{
316 u64 ticks;
317
318 len += q->packet_overhead;
319
320 if (q->cell_size) {
321 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
322
323 if (len > cells * q->cell_size) /* extra cell needed for remainder */
324 cells++;
325 len = cells * (q->cell_size + q->cell_overhead);
326 }
327
328 ticks = (u64)len * NSEC_PER_SEC;
329
330 do_div(ticks, q->rate);
331 return PSCHED_NS2TICKS(ticks);
332}
333
334static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
335{
336 struct sk_buff_head *list = &sch->q;
337 psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
338 struct sk_buff *skb = skb_peek_tail(list);
339
340 /* Optimize for add at tail */
341 if (likely(!skb || tnext >= netem_skb_cb(skb)->time_to_send))
342 return __skb_queue_tail(list, nskb);
343
344 skb_queue_reverse_walk(list, skb) {
345 if (tnext >= netem_skb_cb(skb)->time_to_send)
346 break;
347 }
348
349 __skb_queue_after(list, skb, nskb);
350}
351
352/*
353 * Insert one skb into qdisc.
354 * Note: parent depends on return value to account for queue length.
355 * NET_XMIT_DROP: queue length didn't change.
356 * NET_XMIT_SUCCESS: one skb was queued.
357 */
358static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
359{
360 struct netem_sched_data *q = qdisc_priv(sch);
361 /* We don't fill cb now as skb_unshare() may invalidate it */
362 struct netem_skb_cb *cb;
363 struct sk_buff *skb2;
364 int count = 1;
365
366 /* Random duplication */
367 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
368 ++count;
369
370 /* Drop packet? */
371 if (loss_event(q)) {
372 if (q->ecn && INET_ECN_set_ce(skb))
373 sch->qstats.drops++; /* mark packet */
374 else
375 --count;
376 }
377 if (count == 0) {
378 sch->qstats.drops++;
379 kfree_skb(skb);
380 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
381 }
382
383 skb_orphan(skb);
384
385 /*
386 * If we need to duplicate packet, then re-insert at top of the
387 * qdisc tree, since parent queuer expects that only one
388 * skb will be queued.
389 */
390 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
391 struct Qdisc *rootq = qdisc_root(sch);
392 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
393 q->duplicate = 0;
394
395 qdisc_enqueue_root(skb2, rootq);
396 q->duplicate = dupsave;
397 }
398
399 /*
400 * Randomized packet corruption.
401 * Make copy if needed since we are modifying
402 * If packet is going to be hardware checksummed, then
403 * do it now in software before we mangle it.
404 */
405 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
406 if (!(skb = skb_unshare(skb, GFP_ATOMIC)) ||
407 (skb->ip_summed == CHECKSUM_PARTIAL &&
408 skb_checksum_help(skb)))
409 return qdisc_drop(skb, sch);
410
411 skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
412 }
413
414 if (unlikely(skb_queue_len(&sch->q) >= sch->limit))
415 return qdisc_reshape_fail(skb, sch);
416
417 sch->qstats.backlog += qdisc_pkt_len(skb);
418
419 cb = netem_skb_cb(skb);
420 if (q->gap == 0 || /* not doing reordering */
421 q->counter < q->gap - 1 || /* inside last reordering gap */
422 q->reorder < get_crandom(&q->reorder_cor)) {
423 psched_time_t now;
424 psched_tdiff_t delay;
425
426 delay = tabledist(q->latency, q->jitter,
427 &q->delay_cor, q->delay_dist);
428
429 now = psched_get_time();
430
431 if (q->rate) {
432 struct sk_buff_head *list = &sch->q;
433
434 delay += packet_len_2_sched_time(skb->len, q);
435
436 if (!skb_queue_empty(list)) {
437 /*
438 * Last packet in queue is reference point (now).
439 * First packet in queue is already in flight,
440 * calculate this time bonus and substract
441 * from delay.
442 */
443 delay -= now - netem_skb_cb(skb_peek(list))->time_to_send;
444 now = netem_skb_cb(skb_peek_tail(list))->time_to_send;
445 }
446 }
447
448 cb->time_to_send = now + delay;
449 ++q->counter;
450 tfifo_enqueue(skb, sch);
451 } else {
452 /*
453 * Do re-ordering by putting one out of N packets at the front
454 * of the queue.
455 */
456 cb->time_to_send = psched_get_time();
457 q->counter = 0;
458
459 __skb_queue_head(&sch->q, skb);
460 sch->qstats.requeues++;
461 }
462
463 return NET_XMIT_SUCCESS;
464}
465
466static unsigned int netem_drop(struct Qdisc *sch)
467{
468 struct netem_sched_data *q = qdisc_priv(sch);
469 unsigned int len;
470
471 len = qdisc_queue_drop(sch);
472 if (!len && q->qdisc && q->qdisc->ops->drop)
473 len = q->qdisc->ops->drop(q->qdisc);
474 if (len)
475 sch->qstats.drops++;
476
477 return len;
478}
479
480static struct sk_buff *netem_dequeue(struct Qdisc *sch)
481{
482 struct netem_sched_data *q = qdisc_priv(sch);
483 struct sk_buff *skb;
484
485 if (qdisc_is_throttled(sch))
486 return NULL;
487
488tfifo_dequeue:
489 skb = qdisc_peek_head(sch);
490 if (skb) {
491 const struct netem_skb_cb *cb = netem_skb_cb(skb);
492
493 /* if more time remaining? */
494 if (cb->time_to_send <= psched_get_time()) {
495 __skb_unlink(skb, &sch->q);
496 sch->qstats.backlog -= qdisc_pkt_len(skb);
497
498#ifdef CONFIG_NET_CLS_ACT
499 /*
500 * If it's at ingress let's pretend the delay is
501 * from the network (tstamp will be updated).
502 */
503 if (G_TC_FROM(skb->tc_verd) & AT_INGRESS)
504 skb->tstamp.tv64 = 0;
505#endif
506
507 if (q->qdisc) {
508 int err = qdisc_enqueue(skb, q->qdisc);
509
510 if (unlikely(err != NET_XMIT_SUCCESS)) {
511 if (net_xmit_drop_count(err)) {
512 sch->qstats.drops++;
513 qdisc_tree_decrease_qlen(sch, 1);
514 }
515 }
516 goto tfifo_dequeue;
517 }
518deliver:
519 qdisc_unthrottled(sch);
520 qdisc_bstats_update(sch, skb);
521 return skb;
522 }
523
524 if (q->qdisc) {
525 skb = q->qdisc->ops->dequeue(q->qdisc);
526 if (skb)
527 goto deliver;
528 }
529 qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
530 }
531
532 if (q->qdisc) {
533 skb = q->qdisc->ops->dequeue(q->qdisc);
534 if (skb)
535 goto deliver;
536 }
537 return NULL;
538}
539
540static void netem_reset(struct Qdisc *sch)
541{
542 struct netem_sched_data *q = qdisc_priv(sch);
543
544 qdisc_reset_queue(sch);
545 if (q->qdisc)
546 qdisc_reset(q->qdisc);
547 qdisc_watchdog_cancel(&q->watchdog);
548}
549
550static void dist_free(struct disttable *d)
551{
552 if (d) {
553 if (is_vmalloc_addr(d))
554 vfree(d);
555 else
556 kfree(d);
557 }
558}
559
560/*
561 * Distribution data is a variable size payload containing
562 * signed 16 bit values.
563 */
564static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
565{
566 struct netem_sched_data *q = qdisc_priv(sch);
567 size_t n = nla_len(attr)/sizeof(__s16);
568 const __s16 *data = nla_data(attr);
569 spinlock_t *root_lock;
570 struct disttable *d;
571 int i;
572 size_t s;
573
574 if (n > NETEM_DIST_MAX)
575 return -EINVAL;
576
577 s = sizeof(struct disttable) + n * sizeof(s16);
578 d = kmalloc(s, GFP_KERNEL | __GFP_NOWARN);
579 if (!d)
580 d = vmalloc(s);
581 if (!d)
582 return -ENOMEM;
583
584 d->size = n;
585 for (i = 0; i < n; i++)
586 d->table[i] = data[i];
587
588 root_lock = qdisc_root_sleeping_lock(sch);
589
590 spin_lock_bh(root_lock);
591 swap(q->delay_dist, d);
592 spin_unlock_bh(root_lock);
593
594 dist_free(d);
595 return 0;
596}
597
598static void get_correlation(struct Qdisc *sch, const struct nlattr *attr)
599{
600 struct netem_sched_data *q = qdisc_priv(sch);
601 const struct tc_netem_corr *c = nla_data(attr);
602
603 init_crandom(&q->delay_cor, c->delay_corr);
604 init_crandom(&q->loss_cor, c->loss_corr);
605 init_crandom(&q->dup_cor, c->dup_corr);
606}
607
608static void get_reorder(struct Qdisc *sch, const struct nlattr *attr)
609{
610 struct netem_sched_data *q = qdisc_priv(sch);
611 const struct tc_netem_reorder *r = nla_data(attr);
612
613 q->reorder = r->probability;
614 init_crandom(&q->reorder_cor, r->correlation);
615}
616
617static void get_corrupt(struct Qdisc *sch, const struct nlattr *attr)
618{
619 struct netem_sched_data *q = qdisc_priv(sch);
620 const struct tc_netem_corrupt *r = nla_data(attr);
621
622 q->corrupt = r->probability;
623 init_crandom(&q->corrupt_cor, r->correlation);
624}
625
626static void get_rate(struct Qdisc *sch, const struct nlattr *attr)
627{
628 struct netem_sched_data *q = qdisc_priv(sch);
629 const struct tc_netem_rate *r = nla_data(attr);
630
631 q->rate = r->rate;
632 q->packet_overhead = r->packet_overhead;
633 q->cell_size = r->cell_size;
634 if (q->cell_size)
635 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
636 q->cell_overhead = r->cell_overhead;
637}
638
639static int get_loss_clg(struct Qdisc *sch, const struct nlattr *attr)
640{
641 struct netem_sched_data *q = qdisc_priv(sch);
642 const struct nlattr *la;
643 int rem;
644
645 nla_for_each_nested(la, attr, rem) {
646 u16 type = nla_type(la);
647
648 switch(type) {
649 case NETEM_LOSS_GI: {
650 const struct tc_netem_gimodel *gi = nla_data(la);
651
652 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
653 pr_info("netem: incorrect gi model size\n");
654 return -EINVAL;
655 }
656
657 q->loss_model = CLG_4_STATES;
658
659 q->clg.state = 1;
660 q->clg.a1 = gi->p13;
661 q->clg.a2 = gi->p31;
662 q->clg.a3 = gi->p32;
663 q->clg.a4 = gi->p14;
664 q->clg.a5 = gi->p23;
665 break;
666 }
667
668 case NETEM_LOSS_GE: {
669 const struct tc_netem_gemodel *ge = nla_data(la);
670
671 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
672 pr_info("netem: incorrect ge model size\n");
673 return -EINVAL;
674 }
675
676 q->loss_model = CLG_GILB_ELL;
677 q->clg.state = 1;
678 q->clg.a1 = ge->p;
679 q->clg.a2 = ge->r;
680 q->clg.a3 = ge->h;
681 q->clg.a4 = ge->k1;
682 break;
683 }
684
685 default:
686 pr_info("netem: unknown loss type %u\n", type);
687 return -EINVAL;
688 }
689 }
690
691 return 0;
692}
693
694static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
695 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
696 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
697 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
698 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
699 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
700 [TCA_NETEM_ECN] = { .type = NLA_U32 },
701};
702
703static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
704 const struct nla_policy *policy, int len)
705{
706 int nested_len = nla_len(nla) - NLA_ALIGN(len);
707
708 if (nested_len < 0) {
709 pr_info("netem: invalid attributes len %d\n", nested_len);
710 return -EINVAL;
711 }
712
713 if (nested_len >= nla_attr_size(0))
714 return nla_parse(tb, maxtype, nla_data(nla) + NLA_ALIGN(len),
715 nested_len, policy);
716
717 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
718 return 0;
719}
720
721/* Parse netlink message to set options */
722static int netem_change(struct Qdisc *sch, struct nlattr *opt)
723{
724 struct netem_sched_data *q = qdisc_priv(sch);
725 struct nlattr *tb[TCA_NETEM_MAX + 1];
726 struct tc_netem_qopt *qopt;
727 int ret;
728
729 if (opt == NULL)
730 return -EINVAL;
731
732 qopt = nla_data(opt);
733 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
734 if (ret < 0)
735 return ret;
736
737 sch->limit = qopt->limit;
738
739 q->latency = qopt->latency;
740 q->jitter = qopt->jitter;
741 q->limit = qopt->limit;
742 q->gap = qopt->gap;
743 q->counter = 0;
744 q->loss = qopt->loss;
745 q->duplicate = qopt->duplicate;
746
747 /* for compatibility with earlier versions.
748 * if gap is set, need to assume 100% probability
749 */
750 if (q->gap)
751 q->reorder = ~0;
752
753 if (tb[TCA_NETEM_CORR])
754 get_correlation(sch, tb[TCA_NETEM_CORR]);
755
756 if (tb[TCA_NETEM_DELAY_DIST]) {
757 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
758 if (ret)
759 return ret;
760 }
761
762 if (tb[TCA_NETEM_REORDER])
763 get_reorder(sch, tb[TCA_NETEM_REORDER]);
764
765 if (tb[TCA_NETEM_CORRUPT])
766 get_corrupt(sch, tb[TCA_NETEM_CORRUPT]);
767
768 if (tb[TCA_NETEM_RATE])
769 get_rate(sch, tb[TCA_NETEM_RATE]);
770
771 if (tb[TCA_NETEM_ECN])
772 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
773
774 q->loss_model = CLG_RANDOM;
775 if (tb[TCA_NETEM_LOSS])
776 ret = get_loss_clg(sch, tb[TCA_NETEM_LOSS]);
777
778 return ret;
779}
780
781static int netem_init(struct Qdisc *sch, struct nlattr *opt)
782{
783 struct netem_sched_data *q = qdisc_priv(sch);
784 int ret;
785
786 if (!opt)
787 return -EINVAL;
788
789 qdisc_watchdog_init(&q->watchdog, sch);
790
791 q->loss_model = CLG_RANDOM;
792 ret = netem_change(sch, opt);
793 if (ret)
794 pr_info("netem: change failed\n");
795 return ret;
796}
797
798static void netem_destroy(struct Qdisc *sch)
799{
800 struct netem_sched_data *q = qdisc_priv(sch);
801
802 qdisc_watchdog_cancel(&q->watchdog);
803 if (q->qdisc)
804 qdisc_destroy(q->qdisc);
805 dist_free(q->delay_dist);
806}
807
808static int dump_loss_model(const struct netem_sched_data *q,
809 struct sk_buff *skb)
810{
811 struct nlattr *nest;
812
813 nest = nla_nest_start(skb, TCA_NETEM_LOSS);
814 if (nest == NULL)
815 goto nla_put_failure;
816
817 switch (q->loss_model) {
818 case CLG_RANDOM:
819 /* legacy loss model */
820 nla_nest_cancel(skb, nest);
821 return 0; /* no data */
822
823 case CLG_4_STATES: {
824 struct tc_netem_gimodel gi = {
825 .p13 = q->clg.a1,
826 .p31 = q->clg.a2,
827 .p32 = q->clg.a3,
828 .p14 = q->clg.a4,
829 .p23 = q->clg.a5,
830 };
831
832 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
833 goto nla_put_failure;
834 break;
835 }
836 case CLG_GILB_ELL: {
837 struct tc_netem_gemodel ge = {
838 .p = q->clg.a1,
839 .r = q->clg.a2,
840 .h = q->clg.a3,
841 .k1 = q->clg.a4,
842 };
843
844 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
845 goto nla_put_failure;
846 break;
847 }
848 }
849
850 nla_nest_end(skb, nest);
851 return 0;
852
853nla_put_failure:
854 nla_nest_cancel(skb, nest);
855 return -1;
856}
857
858static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
859{
860 const struct netem_sched_data *q = qdisc_priv(sch);
861 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
862 struct tc_netem_qopt qopt;
863 struct tc_netem_corr cor;
864 struct tc_netem_reorder reorder;
865 struct tc_netem_corrupt corrupt;
866 struct tc_netem_rate rate;
867
868 qopt.latency = q->latency;
869 qopt.jitter = q->jitter;
870 qopt.limit = q->limit;
871 qopt.loss = q->loss;
872 qopt.gap = q->gap;
873 qopt.duplicate = q->duplicate;
874 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
875 goto nla_put_failure;
876
877 cor.delay_corr = q->delay_cor.rho;
878 cor.loss_corr = q->loss_cor.rho;
879 cor.dup_corr = q->dup_cor.rho;
880 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
881 goto nla_put_failure;
882
883 reorder.probability = q->reorder;
884 reorder.correlation = q->reorder_cor.rho;
885 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
886 goto nla_put_failure;
887
888 corrupt.probability = q->corrupt;
889 corrupt.correlation = q->corrupt_cor.rho;
890 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
891 goto nla_put_failure;
892
893 rate.rate = q->rate;
894 rate.packet_overhead = q->packet_overhead;
895 rate.cell_size = q->cell_size;
896 rate.cell_overhead = q->cell_overhead;
897 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
898 goto nla_put_failure;
899
900 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
901 goto nla_put_failure;
902
903 if (dump_loss_model(q, skb) != 0)
904 goto nla_put_failure;
905
906 return nla_nest_end(skb, nla);
907
908nla_put_failure:
909 nlmsg_trim(skb, nla);
910 return -1;
911}
912
913static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
914 struct sk_buff *skb, struct tcmsg *tcm)
915{
916 struct netem_sched_data *q = qdisc_priv(sch);
917
918 if (cl != 1 || !q->qdisc) /* only one class */
919 return -ENOENT;
920
921 tcm->tcm_handle |= TC_H_MIN(1);
922 tcm->tcm_info = q->qdisc->handle;
923
924 return 0;
925}
926
927static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
928 struct Qdisc **old)
929{
930 struct netem_sched_data *q = qdisc_priv(sch);
931
932 sch_tree_lock(sch);
933 *old = q->qdisc;
934 q->qdisc = new;
935 if (*old) {
936 qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
937 qdisc_reset(*old);
938 }
939 sch_tree_unlock(sch);
940
941 return 0;
942}
943
944static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
945{
946 struct netem_sched_data *q = qdisc_priv(sch);
947 return q->qdisc;
948}
949
950static unsigned long netem_get(struct Qdisc *sch, u32 classid)
951{
952 return 1;
953}
954
955static void netem_put(struct Qdisc *sch, unsigned long arg)
956{
957}
958
959static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
960{
961 if (!walker->stop) {
962 if (walker->count >= walker->skip)
963 if (walker->fn(sch, 1, walker) < 0) {
964 walker->stop = 1;
965 return;
966 }
967 walker->count++;
968 }
969}
970
971static const struct Qdisc_class_ops netem_class_ops = {
972 .graft = netem_graft,
973 .leaf = netem_leaf,
974 .get = netem_get,
975 .put = netem_put,
976 .walk = netem_walk,
977 .dump = netem_dump_class,
978};
979
980static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
981 .id = "netem",
982 .cl_ops = &netem_class_ops,
983 .priv_size = sizeof(struct netem_sched_data),
984 .enqueue = netem_enqueue,
985 .dequeue = netem_dequeue,
986 .peek = qdisc_peek_dequeued,
987 .drop = netem_drop,
988 .init = netem_init,
989 .reset = netem_reset,
990 .destroy = netem_destroy,
991 .change = netem_change,
992 .dump = netem_dump,
993 .owner = THIS_MODULE,
994};
995
996
997static int __init netem_module_init(void)
998{
999 pr_info("netem: version " VERSION "\n");
1000 return register_qdisc(&netem_qdisc_ops);
1001}
1002static void __exit netem_module_exit(void)
1003{
1004 unregister_qdisc(&netem_qdisc_ops);
1005}
1006module_init(netem_module_init)
1007module_exit(netem_module_exit)
1008MODULE_LICENSE("GPL");
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/mm.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/types.h>
20#include <linux/kernel.h>
21#include <linux/errno.h>
22#include <linux/skbuff.h>
23#include <linux/vmalloc.h>
24#include <linux/rtnetlink.h>
25#include <linux/reciprocal_div.h>
26#include <linux/rbtree.h>
27
28#include <net/netlink.h>
29#include <net/pkt_sched.h>
30#include <net/inet_ecn.h>
31
32#define VERSION "1.3"
33
34/* Network Emulation Queuing algorithm.
35 ====================================
36
37 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
38 Network Emulation Tool
39 [2] Luigi Rizzo, DummyNet for FreeBSD
40
41 ----------------------------------------------------------------
42
43 This started out as a simple way to delay outgoing packets to
44 test TCP but has grown to include most of the functionality
45 of a full blown network emulator like NISTnet. It can delay
46 packets and add random jitter (and correlation). The random
47 distribution can be loaded from a table as well to provide
48 normal, Pareto, or experimental curves. Packet loss,
49 duplication, and reordering can also be emulated.
50
51 This qdisc does not do classification that can be handled in
52 layering other disciplines. It does not need to do bandwidth
53 control either since that can be handled by using token
54 bucket or other rate control.
55
56 Correlated Loss Generator models
57
58 Added generation of correlated loss according to the
59 "Gilbert-Elliot" model, a 4-state markov model.
60
61 References:
62 [1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG
63 [2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
64 and intuitive loss model for packet networks and its implementation
65 in the Netem module in the Linux kernel", available in [1]
66
67 Authors: Stefano Salsano <stefano.salsano at uniroma2.it
68 Fabio Ludovici <fabio.ludovici at yahoo.it>
69*/
70
71struct netem_sched_data {
72 /* internal t(ime)fifo qdisc uses t_root and sch->limit */
73 struct rb_root t_root;
74
75 /* optional qdisc for classful handling (NULL at netem init) */
76 struct Qdisc *qdisc;
77
78 struct qdisc_watchdog watchdog;
79
80 s64 latency;
81 s64 jitter;
82
83 u32 loss;
84 u32 ecn;
85 u32 limit;
86 u32 counter;
87 u32 gap;
88 u32 duplicate;
89 u32 reorder;
90 u32 corrupt;
91 u64 rate;
92 s32 packet_overhead;
93 u32 cell_size;
94 struct reciprocal_value cell_size_reciprocal;
95 s32 cell_overhead;
96
97 struct crndstate {
98 u32 last;
99 u32 rho;
100 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
101
102 struct disttable {
103 u32 size;
104 s16 table[0];
105 } *delay_dist;
106
107 enum {
108 CLG_RANDOM,
109 CLG_4_STATES,
110 CLG_GILB_ELL,
111 } loss_model;
112
113 enum {
114 TX_IN_GAP_PERIOD = 1,
115 TX_IN_BURST_PERIOD,
116 LOST_IN_GAP_PERIOD,
117 LOST_IN_BURST_PERIOD,
118 } _4_state_model;
119
120 enum {
121 GOOD_STATE = 1,
122 BAD_STATE,
123 } GE_state_model;
124
125 /* Correlated Loss Generation models */
126 struct clgstate {
127 /* state of the Markov chain */
128 u8 state;
129
130 /* 4-states and Gilbert-Elliot models */
131 u32 a1; /* p13 for 4-states or p for GE */
132 u32 a2; /* p31 for 4-states or r for GE */
133 u32 a3; /* p32 for 4-states or h for GE */
134 u32 a4; /* p14 for 4-states or 1-k for GE */
135 u32 a5; /* p23 used only in 4-states */
136 } clg;
137
138 struct tc_netem_slot slot_config;
139 struct slotstate {
140 u64 slot_next;
141 s32 packets_left;
142 s32 bytes_left;
143 } slot;
144
145};
146
147/* Time stamp put into socket buffer control block
148 * Only valid when skbs are in our internal t(ime)fifo queue.
149 *
150 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,
151 * and skb->next & skb->prev are scratch space for a qdisc,
152 * we save skb->tstamp value in skb->cb[] before destroying it.
153 */
154struct netem_skb_cb {
155 u64 time_to_send;
156};
157
158static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
159{
160 /* we assume we can use skb next/prev/tstamp as storage for rb_node */
161 qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb));
162 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
163}
164
165/* init_crandom - initialize correlated random number generator
166 * Use entropy source for initial seed.
167 */
168static void init_crandom(struct crndstate *state, unsigned long rho)
169{
170 state->rho = rho;
171 state->last = prandom_u32();
172}
173
174/* get_crandom - correlated random number generator
175 * Next number depends on last value.
176 * rho is scaled to avoid floating point.
177 */
178static u32 get_crandom(struct crndstate *state)
179{
180 u64 value, rho;
181 unsigned long answer;
182
183 if (state->rho == 0) /* no correlation */
184 return prandom_u32();
185
186 value = prandom_u32();
187 rho = (u64)state->rho + 1;
188 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
189 state->last = answer;
190 return answer;
191}
192
193/* loss_4state - 4-state model loss generator
194 * Generates losses according to the 4-state Markov chain adopted in
195 * the GI (General and Intuitive) loss model.
196 */
197static bool loss_4state(struct netem_sched_data *q)
198{
199 struct clgstate *clg = &q->clg;
200 u32 rnd = prandom_u32();
201
202 /*
203 * Makes a comparison between rnd and the transition
204 * probabilities outgoing from the current state, then decides the
205 * next state and if the next packet has to be transmitted or lost.
206 * The four states correspond to:
207 * TX_IN_GAP_PERIOD => successfully transmitted packets within a gap period
208 * LOST_IN_BURST_PERIOD => isolated losses within a gap period
209 * LOST_IN_GAP_PERIOD => lost packets within a burst period
210 * TX_IN_GAP_PERIOD => successfully transmitted packets within a burst period
211 */
212 switch (clg->state) {
213 case TX_IN_GAP_PERIOD:
214 if (rnd < clg->a4) {
215 clg->state = LOST_IN_BURST_PERIOD;
216 return true;
217 } else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {
218 clg->state = LOST_IN_GAP_PERIOD;
219 return true;
220 } else if (clg->a1 + clg->a4 < rnd) {
221 clg->state = TX_IN_GAP_PERIOD;
222 }
223
224 break;
225 case TX_IN_BURST_PERIOD:
226 if (rnd < clg->a5) {
227 clg->state = LOST_IN_GAP_PERIOD;
228 return true;
229 } else {
230 clg->state = TX_IN_BURST_PERIOD;
231 }
232
233 break;
234 case LOST_IN_GAP_PERIOD:
235 if (rnd < clg->a3)
236 clg->state = TX_IN_BURST_PERIOD;
237 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
238 clg->state = TX_IN_GAP_PERIOD;
239 } else if (clg->a2 + clg->a3 < rnd) {
240 clg->state = LOST_IN_GAP_PERIOD;
241 return true;
242 }
243 break;
244 case LOST_IN_BURST_PERIOD:
245 clg->state = TX_IN_GAP_PERIOD;
246 break;
247 }
248
249 return false;
250}
251
252/* loss_gilb_ell - Gilbert-Elliot model loss generator
253 * Generates losses according to the Gilbert-Elliot loss model or
254 * its special cases (Gilbert or Simple Gilbert)
255 *
256 * Makes a comparison between random number and the transition
257 * probabilities outgoing from the current state, then decides the
258 * next state. A second random number is extracted and the comparison
259 * with the loss probability of the current state decides if the next
260 * packet will be transmitted or lost.
261 */
262static bool loss_gilb_ell(struct netem_sched_data *q)
263{
264 struct clgstate *clg = &q->clg;
265
266 switch (clg->state) {
267 case GOOD_STATE:
268 if (prandom_u32() < clg->a1)
269 clg->state = BAD_STATE;
270 if (prandom_u32() < clg->a4)
271 return true;
272 break;
273 case BAD_STATE:
274 if (prandom_u32() < clg->a2)
275 clg->state = GOOD_STATE;
276 if (prandom_u32() > clg->a3)
277 return true;
278 }
279
280 return false;
281}
282
283static bool loss_event(struct netem_sched_data *q)
284{
285 switch (q->loss_model) {
286 case CLG_RANDOM:
287 /* Random packet drop 0 => none, ~0 => all */
288 return q->loss && q->loss >= get_crandom(&q->loss_cor);
289
290 case CLG_4_STATES:
291 /* 4state loss model algorithm (used also for GI model)
292 * Extracts a value from the markov 4 state loss generator,
293 * if it is 1 drops a packet and if needed writes the event in
294 * the kernel logs
295 */
296 return loss_4state(q);
297
298 case CLG_GILB_ELL:
299 /* Gilbert-Elliot loss model algorithm
300 * Extracts a value from the Gilbert-Elliot loss generator,
301 * if it is 1 drops a packet and if needed writes the event in
302 * the kernel logs
303 */
304 return loss_gilb_ell(q);
305 }
306
307 return false; /* not reached */
308}
309
310
311/* tabledist - return a pseudo-randomly distributed value with mean mu and
312 * std deviation sigma. Uses table lookup to approximate the desired
313 * distribution, and a uniformly-distributed pseudo-random source.
314 */
315static s64 tabledist(s64 mu, s32 sigma,
316 struct crndstate *state,
317 const struct disttable *dist)
318{
319 s64 x;
320 long t;
321 u32 rnd;
322
323 if (sigma == 0)
324 return mu;
325
326 rnd = get_crandom(state);
327
328 /* default uniform distribution */
329 if (dist == NULL)
330 return ((rnd % (2 * sigma)) + mu) - sigma;
331
332 t = dist->table[rnd % dist->size];
333 x = (sigma % NETEM_DIST_SCALE) * t;
334 if (x >= 0)
335 x += NETEM_DIST_SCALE/2;
336 else
337 x -= NETEM_DIST_SCALE/2;
338
339 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
340}
341
342static u64 packet_time_ns(u64 len, const struct netem_sched_data *q)
343{
344 len += q->packet_overhead;
345
346 if (q->cell_size) {
347 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
348
349 if (len > cells * q->cell_size) /* extra cell needed for remainder */
350 cells++;
351 len = cells * (q->cell_size + q->cell_overhead);
352 }
353
354 return div64_u64(len * NSEC_PER_SEC, q->rate);
355}
356
357static void tfifo_reset(struct Qdisc *sch)
358{
359 struct netem_sched_data *q = qdisc_priv(sch);
360 struct rb_node *p = rb_first(&q->t_root);
361
362 while (p) {
363 struct sk_buff *skb = rb_to_skb(p);
364
365 p = rb_next(p);
366 rb_erase(&skb->rbnode, &q->t_root);
367 rtnl_kfree_skbs(skb, skb);
368 }
369}
370
371static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
372{
373 struct netem_sched_data *q = qdisc_priv(sch);
374 u64 tnext = netem_skb_cb(nskb)->time_to_send;
375 struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
376
377 while (*p) {
378 struct sk_buff *skb;
379
380 parent = *p;
381 skb = rb_to_skb(parent);
382 if (tnext >= netem_skb_cb(skb)->time_to_send)
383 p = &parent->rb_right;
384 else
385 p = &parent->rb_left;
386 }
387 rb_link_node(&nskb->rbnode, parent, p);
388 rb_insert_color(&nskb->rbnode, &q->t_root);
389 sch->q.qlen++;
390}
391
392/* netem can't properly corrupt a megapacket (like we get from GSO), so instead
393 * when we statistically choose to corrupt one, we instead segment it, returning
394 * the first packet to be corrupted, and re-enqueue the remaining frames
395 */
396static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
397 struct sk_buff **to_free)
398{
399 struct sk_buff *segs;
400 netdev_features_t features = netif_skb_features(skb);
401
402 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
403
404 if (IS_ERR_OR_NULL(segs)) {
405 qdisc_drop(skb, sch, to_free);
406 return NULL;
407 }
408 consume_skb(skb);
409 return segs;
410}
411
412static void netem_enqueue_skb_head(struct qdisc_skb_head *qh, struct sk_buff *skb)
413{
414 skb->next = qh->head;
415
416 if (!qh->head)
417 qh->tail = skb;
418 qh->head = skb;
419 qh->qlen++;
420}
421
422/*
423 * Insert one skb into qdisc.
424 * Note: parent depends on return value to account for queue length.
425 * NET_XMIT_DROP: queue length didn't change.
426 * NET_XMIT_SUCCESS: one skb was queued.
427 */
428static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
429 struct sk_buff **to_free)
430{
431 struct netem_sched_data *q = qdisc_priv(sch);
432 /* We don't fill cb now as skb_unshare() may invalidate it */
433 struct netem_skb_cb *cb;
434 struct sk_buff *skb2;
435 struct sk_buff *segs = NULL;
436 unsigned int len = 0, last_len, prev_len = qdisc_pkt_len(skb);
437 int nb = 0;
438 int count = 1;
439 int rc = NET_XMIT_SUCCESS;
440
441 /* Random duplication */
442 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
443 ++count;
444
445 /* Drop packet? */
446 if (loss_event(q)) {
447 if (q->ecn && INET_ECN_set_ce(skb))
448 qdisc_qstats_drop(sch); /* mark packet */
449 else
450 --count;
451 }
452 if (count == 0) {
453 qdisc_qstats_drop(sch);
454 __qdisc_drop(skb, to_free);
455 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
456 }
457
458 /* If a delay is expected, orphan the skb. (orphaning usually takes
459 * place at TX completion time, so _before_ the link transit delay)
460 */
461 if (q->latency || q->jitter || q->rate)
462 skb_orphan_partial(skb);
463
464 /*
465 * If we need to duplicate packet, then re-insert at top of the
466 * qdisc tree, since parent queuer expects that only one
467 * skb will be queued.
468 */
469 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
470 struct Qdisc *rootq = qdisc_root(sch);
471 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
472
473 q->duplicate = 0;
474 rootq->enqueue(skb2, rootq, to_free);
475 q->duplicate = dupsave;
476 }
477
478 /*
479 * Randomized packet corruption.
480 * Make copy if needed since we are modifying
481 * If packet is going to be hardware checksummed, then
482 * do it now in software before we mangle it.
483 */
484 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
485 if (skb_is_gso(skb)) {
486 segs = netem_segment(skb, sch, to_free);
487 if (!segs)
488 return NET_XMIT_DROP;
489 } else {
490 segs = skb;
491 }
492
493 skb = segs;
494 segs = segs->next;
495
496 skb = skb_unshare(skb, GFP_ATOMIC);
497 if (unlikely(!skb)) {
498 qdisc_qstats_drop(sch);
499 goto finish_segs;
500 }
501 if (skb->ip_summed == CHECKSUM_PARTIAL &&
502 skb_checksum_help(skb)) {
503 qdisc_drop(skb, sch, to_free);
504 goto finish_segs;
505 }
506
507 skb->data[prandom_u32() % skb_headlen(skb)] ^=
508 1<<(prandom_u32() % 8);
509 }
510
511 if (unlikely(sch->q.qlen >= sch->limit))
512 return qdisc_drop_all(skb, sch, to_free);
513
514 qdisc_qstats_backlog_inc(sch, skb);
515
516 cb = netem_skb_cb(skb);
517 if (q->gap == 0 || /* not doing reordering */
518 q->counter < q->gap - 1 || /* inside last reordering gap */
519 q->reorder < get_crandom(&q->reorder_cor)) {
520 u64 now;
521 s64 delay;
522
523 delay = tabledist(q->latency, q->jitter,
524 &q->delay_cor, q->delay_dist);
525
526 now = ktime_get_ns();
527
528 if (q->rate) {
529 struct netem_skb_cb *last = NULL;
530
531 if (sch->q.tail)
532 last = netem_skb_cb(sch->q.tail);
533 if (q->t_root.rb_node) {
534 struct sk_buff *t_skb;
535 struct netem_skb_cb *t_last;
536
537 t_skb = skb_rb_last(&q->t_root);
538 t_last = netem_skb_cb(t_skb);
539 if (!last ||
540 t_last->time_to_send > last->time_to_send) {
541 last = t_last;
542 }
543 }
544
545 if (last) {
546 /*
547 * Last packet in queue is reference point (now),
548 * calculate this time bonus and subtract
549 * from delay.
550 */
551 delay -= last->time_to_send - now;
552 delay = max_t(s64, 0, delay);
553 now = last->time_to_send;
554 }
555
556 delay += packet_time_ns(qdisc_pkt_len(skb), q);
557 }
558
559 cb->time_to_send = now + delay;
560 ++q->counter;
561 tfifo_enqueue(skb, sch);
562 } else {
563 /*
564 * Do re-ordering by putting one out of N packets at the front
565 * of the queue.
566 */
567 cb->time_to_send = ktime_get_ns();
568 q->counter = 0;
569
570 netem_enqueue_skb_head(&sch->q, skb);
571 sch->qstats.requeues++;
572 }
573
574finish_segs:
575 if (segs) {
576 while (segs) {
577 skb2 = segs->next;
578 segs->next = NULL;
579 qdisc_skb_cb(segs)->pkt_len = segs->len;
580 last_len = segs->len;
581 rc = qdisc_enqueue(segs, sch, to_free);
582 if (rc != NET_XMIT_SUCCESS) {
583 if (net_xmit_drop_count(rc))
584 qdisc_qstats_drop(sch);
585 } else {
586 nb++;
587 len += last_len;
588 }
589 segs = skb2;
590 }
591 sch->q.qlen += nb;
592 if (nb > 1)
593 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
594 }
595 return NET_XMIT_SUCCESS;
596}
597
598/* Delay the next round with a new future slot with a
599 * correct number of bytes and packets.
600 */
601
602static void get_slot_next(struct netem_sched_data *q, u64 now)
603{
604 q->slot.slot_next = now + q->slot_config.min_delay +
605 (prandom_u32() *
606 (q->slot_config.max_delay -
607 q->slot_config.min_delay) >> 32);
608 q->slot.packets_left = q->slot_config.max_packets;
609 q->slot.bytes_left = q->slot_config.max_bytes;
610}
611
612static struct sk_buff *netem_dequeue(struct Qdisc *sch)
613{
614 struct netem_sched_data *q = qdisc_priv(sch);
615 struct sk_buff *skb;
616 struct rb_node *p;
617
618tfifo_dequeue:
619 skb = __qdisc_dequeue_head(&sch->q);
620 if (skb) {
621 qdisc_qstats_backlog_dec(sch, skb);
622deliver:
623 qdisc_bstats_update(sch, skb);
624 return skb;
625 }
626 p = rb_first(&q->t_root);
627 if (p) {
628 u64 time_to_send;
629 u64 now = ktime_get_ns();
630
631 skb = rb_to_skb(p);
632
633 /* if more time remaining? */
634 time_to_send = netem_skb_cb(skb)->time_to_send;
635 if (q->slot.slot_next && q->slot.slot_next < time_to_send)
636 get_slot_next(q, now);
637
638 if (time_to_send <= now && q->slot.slot_next <= now) {
639 rb_erase(p, &q->t_root);
640 sch->q.qlen--;
641 qdisc_qstats_backlog_dec(sch, skb);
642 skb->next = NULL;
643 skb->prev = NULL;
644 /* skb->dev shares skb->rbnode area,
645 * we need to restore its value.
646 */
647 skb->dev = qdisc_dev(sch);
648
649#ifdef CONFIG_NET_CLS_ACT
650 /*
651 * If it's at ingress let's pretend the delay is
652 * from the network (tstamp will be updated).
653 */
654 if (skb->tc_redirected && skb->tc_from_ingress)
655 skb->tstamp = 0;
656#endif
657
658 if (q->slot.slot_next) {
659 q->slot.packets_left--;
660 q->slot.bytes_left -= qdisc_pkt_len(skb);
661 if (q->slot.packets_left <= 0 ||
662 q->slot.bytes_left <= 0)
663 get_slot_next(q, now);
664 }
665
666 if (q->qdisc) {
667 unsigned int pkt_len = qdisc_pkt_len(skb);
668 struct sk_buff *to_free = NULL;
669 int err;
670
671 err = qdisc_enqueue(skb, q->qdisc, &to_free);
672 kfree_skb_list(to_free);
673 if (err != NET_XMIT_SUCCESS &&
674 net_xmit_drop_count(err)) {
675 qdisc_qstats_drop(sch);
676 qdisc_tree_reduce_backlog(sch, 1,
677 pkt_len);
678 }
679 goto tfifo_dequeue;
680 }
681 goto deliver;
682 }
683
684 if (q->qdisc) {
685 skb = q->qdisc->ops->dequeue(q->qdisc);
686 if (skb)
687 goto deliver;
688 }
689
690 qdisc_watchdog_schedule_ns(&q->watchdog,
691 max(time_to_send,
692 q->slot.slot_next));
693 }
694
695 if (q->qdisc) {
696 skb = q->qdisc->ops->dequeue(q->qdisc);
697 if (skb)
698 goto deliver;
699 }
700 return NULL;
701}
702
703static void netem_reset(struct Qdisc *sch)
704{
705 struct netem_sched_data *q = qdisc_priv(sch);
706
707 qdisc_reset_queue(sch);
708 tfifo_reset(sch);
709 if (q->qdisc)
710 qdisc_reset(q->qdisc);
711 qdisc_watchdog_cancel(&q->watchdog);
712}
713
714static void dist_free(struct disttable *d)
715{
716 kvfree(d);
717}
718
719/*
720 * Distribution data is a variable size payload containing
721 * signed 16 bit values.
722 */
723
724static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
725{
726 struct netem_sched_data *q = qdisc_priv(sch);
727 size_t n = nla_len(attr)/sizeof(__s16);
728 const __s16 *data = nla_data(attr);
729 spinlock_t *root_lock;
730 struct disttable *d;
731 int i;
732
733 if (n > NETEM_DIST_MAX)
734 return -EINVAL;
735
736 d = kvmalloc(sizeof(struct disttable) + n * sizeof(s16), GFP_KERNEL);
737 if (!d)
738 return -ENOMEM;
739
740 d->size = n;
741 for (i = 0; i < n; i++)
742 d->table[i] = data[i];
743
744 root_lock = qdisc_root_sleeping_lock(sch);
745
746 spin_lock_bh(root_lock);
747 swap(q->delay_dist, d);
748 spin_unlock_bh(root_lock);
749
750 dist_free(d);
751 return 0;
752}
753
754static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
755{
756 const struct tc_netem_slot *c = nla_data(attr);
757
758 q->slot_config = *c;
759 if (q->slot_config.max_packets == 0)
760 q->slot_config.max_packets = INT_MAX;
761 if (q->slot_config.max_bytes == 0)
762 q->slot_config.max_bytes = INT_MAX;
763 q->slot.packets_left = q->slot_config.max_packets;
764 q->slot.bytes_left = q->slot_config.max_bytes;
765 if (q->slot_config.min_delay | q->slot_config.max_delay)
766 q->slot.slot_next = ktime_get_ns();
767 else
768 q->slot.slot_next = 0;
769}
770
771static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
772{
773 const struct tc_netem_corr *c = nla_data(attr);
774
775 init_crandom(&q->delay_cor, c->delay_corr);
776 init_crandom(&q->loss_cor, c->loss_corr);
777 init_crandom(&q->dup_cor, c->dup_corr);
778}
779
780static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
781{
782 const struct tc_netem_reorder *r = nla_data(attr);
783
784 q->reorder = r->probability;
785 init_crandom(&q->reorder_cor, r->correlation);
786}
787
788static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
789{
790 const struct tc_netem_corrupt *r = nla_data(attr);
791
792 q->corrupt = r->probability;
793 init_crandom(&q->corrupt_cor, r->correlation);
794}
795
796static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
797{
798 const struct tc_netem_rate *r = nla_data(attr);
799
800 q->rate = r->rate;
801 q->packet_overhead = r->packet_overhead;
802 q->cell_size = r->cell_size;
803 q->cell_overhead = r->cell_overhead;
804 if (q->cell_size)
805 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
806 else
807 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
808}
809
810static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
811{
812 const struct nlattr *la;
813 int rem;
814
815 nla_for_each_nested(la, attr, rem) {
816 u16 type = nla_type(la);
817
818 switch (type) {
819 case NETEM_LOSS_GI: {
820 const struct tc_netem_gimodel *gi = nla_data(la);
821
822 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
823 pr_info("netem: incorrect gi model size\n");
824 return -EINVAL;
825 }
826
827 q->loss_model = CLG_4_STATES;
828
829 q->clg.state = TX_IN_GAP_PERIOD;
830 q->clg.a1 = gi->p13;
831 q->clg.a2 = gi->p31;
832 q->clg.a3 = gi->p32;
833 q->clg.a4 = gi->p14;
834 q->clg.a5 = gi->p23;
835 break;
836 }
837
838 case NETEM_LOSS_GE: {
839 const struct tc_netem_gemodel *ge = nla_data(la);
840
841 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
842 pr_info("netem: incorrect ge model size\n");
843 return -EINVAL;
844 }
845
846 q->loss_model = CLG_GILB_ELL;
847 q->clg.state = GOOD_STATE;
848 q->clg.a1 = ge->p;
849 q->clg.a2 = ge->r;
850 q->clg.a3 = ge->h;
851 q->clg.a4 = ge->k1;
852 break;
853 }
854
855 default:
856 pr_info("netem: unknown loss type %u\n", type);
857 return -EINVAL;
858 }
859 }
860
861 return 0;
862}
863
864static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
865 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
866 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
867 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
868 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
869 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
870 [TCA_NETEM_ECN] = { .type = NLA_U32 },
871 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
872 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
873 [TCA_NETEM_JITTER64] = { .type = NLA_S64 },
874 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
875};
876
877static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
878 const struct nla_policy *policy, int len)
879{
880 int nested_len = nla_len(nla) - NLA_ALIGN(len);
881
882 if (nested_len < 0) {
883 pr_info("netem: invalid attributes len %d\n", nested_len);
884 return -EINVAL;
885 }
886
887 if (nested_len >= nla_attr_size(0))
888 return nla_parse(tb, maxtype, nla_data(nla) + NLA_ALIGN(len),
889 nested_len, policy, NULL);
890
891 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
892 return 0;
893}
894
895/* Parse netlink message to set options */
896static int netem_change(struct Qdisc *sch, struct nlattr *opt,
897 struct netlink_ext_ack *extack)
898{
899 struct netem_sched_data *q = qdisc_priv(sch);
900 struct nlattr *tb[TCA_NETEM_MAX + 1];
901 struct tc_netem_qopt *qopt;
902 struct clgstate old_clg;
903 int old_loss_model = CLG_RANDOM;
904 int ret;
905
906 if (opt == NULL)
907 return -EINVAL;
908
909 qopt = nla_data(opt);
910 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
911 if (ret < 0)
912 return ret;
913
914 /* backup q->clg and q->loss_model */
915 old_clg = q->clg;
916 old_loss_model = q->loss_model;
917
918 if (tb[TCA_NETEM_LOSS]) {
919 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
920 if (ret) {
921 q->loss_model = old_loss_model;
922 return ret;
923 }
924 } else {
925 q->loss_model = CLG_RANDOM;
926 }
927
928 if (tb[TCA_NETEM_DELAY_DIST]) {
929 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
930 if (ret) {
931 /* recover clg and loss_model, in case of
932 * q->clg and q->loss_model were modified
933 * in get_loss_clg()
934 */
935 q->clg = old_clg;
936 q->loss_model = old_loss_model;
937 return ret;
938 }
939 }
940
941 sch->limit = qopt->limit;
942
943 q->latency = PSCHED_TICKS2NS(qopt->latency);
944 q->jitter = PSCHED_TICKS2NS(qopt->jitter);
945 q->limit = qopt->limit;
946 q->gap = qopt->gap;
947 q->counter = 0;
948 q->loss = qopt->loss;
949 q->duplicate = qopt->duplicate;
950
951 /* for compatibility with earlier versions.
952 * if gap is set, need to assume 100% probability
953 */
954 if (q->gap)
955 q->reorder = ~0;
956
957 if (tb[TCA_NETEM_CORR])
958 get_correlation(q, tb[TCA_NETEM_CORR]);
959
960 if (tb[TCA_NETEM_REORDER])
961 get_reorder(q, tb[TCA_NETEM_REORDER]);
962
963 if (tb[TCA_NETEM_CORRUPT])
964 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
965
966 if (tb[TCA_NETEM_RATE])
967 get_rate(q, tb[TCA_NETEM_RATE]);
968
969 if (tb[TCA_NETEM_RATE64])
970 q->rate = max_t(u64, q->rate,
971 nla_get_u64(tb[TCA_NETEM_RATE64]));
972
973 if (tb[TCA_NETEM_LATENCY64])
974 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
975
976 if (tb[TCA_NETEM_JITTER64])
977 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
978
979 if (tb[TCA_NETEM_ECN])
980 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
981
982 if (tb[TCA_NETEM_SLOT])
983 get_slot(q, tb[TCA_NETEM_SLOT]);
984
985 return ret;
986}
987
988static int netem_init(struct Qdisc *sch, struct nlattr *opt,
989 struct netlink_ext_ack *extack)
990{
991 struct netem_sched_data *q = qdisc_priv(sch);
992 int ret;
993
994 qdisc_watchdog_init(&q->watchdog, sch);
995
996 if (!opt)
997 return -EINVAL;
998
999 q->loss_model = CLG_RANDOM;
1000 ret = netem_change(sch, opt, extack);
1001 if (ret)
1002 pr_info("netem: change failed\n");
1003 return ret;
1004}
1005
1006static void netem_destroy(struct Qdisc *sch)
1007{
1008 struct netem_sched_data *q = qdisc_priv(sch);
1009
1010 qdisc_watchdog_cancel(&q->watchdog);
1011 if (q->qdisc)
1012 qdisc_destroy(q->qdisc);
1013 dist_free(q->delay_dist);
1014}
1015
1016static int dump_loss_model(const struct netem_sched_data *q,
1017 struct sk_buff *skb)
1018{
1019 struct nlattr *nest;
1020
1021 nest = nla_nest_start(skb, TCA_NETEM_LOSS);
1022 if (nest == NULL)
1023 goto nla_put_failure;
1024
1025 switch (q->loss_model) {
1026 case CLG_RANDOM:
1027 /* legacy loss model */
1028 nla_nest_cancel(skb, nest);
1029 return 0; /* no data */
1030
1031 case CLG_4_STATES: {
1032 struct tc_netem_gimodel gi = {
1033 .p13 = q->clg.a1,
1034 .p31 = q->clg.a2,
1035 .p32 = q->clg.a3,
1036 .p14 = q->clg.a4,
1037 .p23 = q->clg.a5,
1038 };
1039
1040 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
1041 goto nla_put_failure;
1042 break;
1043 }
1044 case CLG_GILB_ELL: {
1045 struct tc_netem_gemodel ge = {
1046 .p = q->clg.a1,
1047 .r = q->clg.a2,
1048 .h = q->clg.a3,
1049 .k1 = q->clg.a4,
1050 };
1051
1052 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1053 goto nla_put_failure;
1054 break;
1055 }
1056 }
1057
1058 nla_nest_end(skb, nest);
1059 return 0;
1060
1061nla_put_failure:
1062 nla_nest_cancel(skb, nest);
1063 return -1;
1064}
1065
1066static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1067{
1068 const struct netem_sched_data *q = qdisc_priv(sch);
1069 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1070 struct tc_netem_qopt qopt;
1071 struct tc_netem_corr cor;
1072 struct tc_netem_reorder reorder;
1073 struct tc_netem_corrupt corrupt;
1074 struct tc_netem_rate rate;
1075 struct tc_netem_slot slot;
1076
1077 qopt.latency = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->latency),
1078 UINT_MAX);
1079 qopt.jitter = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->jitter),
1080 UINT_MAX);
1081 qopt.limit = q->limit;
1082 qopt.loss = q->loss;
1083 qopt.gap = q->gap;
1084 qopt.duplicate = q->duplicate;
1085 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1086 goto nla_put_failure;
1087
1088 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
1089 goto nla_put_failure;
1090
1091 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
1092 goto nla_put_failure;
1093
1094 cor.delay_corr = q->delay_cor.rho;
1095 cor.loss_corr = q->loss_cor.rho;
1096 cor.dup_corr = q->dup_cor.rho;
1097 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1098 goto nla_put_failure;
1099
1100 reorder.probability = q->reorder;
1101 reorder.correlation = q->reorder_cor.rho;
1102 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1103 goto nla_put_failure;
1104
1105 corrupt.probability = q->corrupt;
1106 corrupt.correlation = q->corrupt_cor.rho;
1107 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1108 goto nla_put_failure;
1109
1110 if (q->rate >= (1ULL << 32)) {
1111 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1112 TCA_NETEM_PAD))
1113 goto nla_put_failure;
1114 rate.rate = ~0U;
1115 } else {
1116 rate.rate = q->rate;
1117 }
1118 rate.packet_overhead = q->packet_overhead;
1119 rate.cell_size = q->cell_size;
1120 rate.cell_overhead = q->cell_overhead;
1121 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1122 goto nla_put_failure;
1123
1124 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1125 goto nla_put_failure;
1126
1127 if (dump_loss_model(q, skb) != 0)
1128 goto nla_put_failure;
1129
1130 if (q->slot_config.min_delay | q->slot_config.max_delay) {
1131 slot = q->slot_config;
1132 if (slot.max_packets == INT_MAX)
1133 slot.max_packets = 0;
1134 if (slot.max_bytes == INT_MAX)
1135 slot.max_bytes = 0;
1136 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
1137 goto nla_put_failure;
1138 }
1139
1140 return nla_nest_end(skb, nla);
1141
1142nla_put_failure:
1143 nlmsg_trim(skb, nla);
1144 return -1;
1145}
1146
1147static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1148 struct sk_buff *skb, struct tcmsg *tcm)
1149{
1150 struct netem_sched_data *q = qdisc_priv(sch);
1151
1152 if (cl != 1 || !q->qdisc) /* only one class */
1153 return -ENOENT;
1154
1155 tcm->tcm_handle |= TC_H_MIN(1);
1156 tcm->tcm_info = q->qdisc->handle;
1157
1158 return 0;
1159}
1160
1161static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1162 struct Qdisc **old, struct netlink_ext_ack *extack)
1163{
1164 struct netem_sched_data *q = qdisc_priv(sch);
1165
1166 *old = qdisc_replace(sch, new, &q->qdisc);
1167 return 0;
1168}
1169
1170static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1171{
1172 struct netem_sched_data *q = qdisc_priv(sch);
1173 return q->qdisc;
1174}
1175
1176static unsigned long netem_find(struct Qdisc *sch, u32 classid)
1177{
1178 return 1;
1179}
1180
1181static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1182{
1183 if (!walker->stop) {
1184 if (walker->count >= walker->skip)
1185 if (walker->fn(sch, 1, walker) < 0) {
1186 walker->stop = 1;
1187 return;
1188 }
1189 walker->count++;
1190 }
1191}
1192
1193static const struct Qdisc_class_ops netem_class_ops = {
1194 .graft = netem_graft,
1195 .leaf = netem_leaf,
1196 .find = netem_find,
1197 .walk = netem_walk,
1198 .dump = netem_dump_class,
1199};
1200
1201static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1202 .id = "netem",
1203 .cl_ops = &netem_class_ops,
1204 .priv_size = sizeof(struct netem_sched_data),
1205 .enqueue = netem_enqueue,
1206 .dequeue = netem_dequeue,
1207 .peek = qdisc_peek_dequeued,
1208 .init = netem_init,
1209 .reset = netem_reset,
1210 .destroy = netem_destroy,
1211 .change = netem_change,
1212 .dump = netem_dump,
1213 .owner = THIS_MODULE,
1214};
1215
1216
1217static int __init netem_module_init(void)
1218{
1219 pr_info("netem: version " VERSION "\n");
1220 return register_qdisc(&netem_qdisc_ops);
1221}
1222static void __exit netem_module_exit(void)
1223{
1224 unregister_qdisc(&netem_qdisc_ops);
1225}
1226module_init(netem_module_init)
1227module_exit(netem_module_exit)
1228MODULE_LICENSE("GPL");