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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * net/sched/sch_netem.c Network emulator
4 *
5 * Many of the algorithms and ideas for this came from
6 * NIST Net which is not copyrighted.
7 *
8 * Authors: Stephen Hemminger <shemminger@osdl.org>
9 * Catalin(ux aka Dino) BOIE <catab at umbrella dot ro>
10 */
11
12#include <linux/mm.h>
13#include <linux/module.h>
14#include <linux/slab.h>
15#include <linux/types.h>
16#include <linux/kernel.h>
17#include <linux/errno.h>
18#include <linux/skbuff.h>
19#include <linux/vmalloc.h>
20#include <linux/prandom.h>
21#include <linux/rtnetlink.h>
22#include <linux/reciprocal_div.h>
23#include <linux/rbtree.h>
24
25#include <net/gso.h>
26#include <net/netlink.h>
27#include <net/pkt_sched.h>
28#include <net/inet_ecn.h>
29
30#define VERSION "1.3"
31
32/* Network Emulation Queuing algorithm.
33 ====================================
34
35 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
36 Network Emulation Tool
37 [2] Luigi Rizzo, DummyNet for FreeBSD
38
39 ----------------------------------------------------------------
40
41 This started out as a simple way to delay outgoing packets to
42 test TCP but has grown to include most of the functionality
43 of a full blown network emulator like NISTnet. It can delay
44 packets and add random jitter (and correlation). The random
45 distribution can be loaded from a table as well to provide
46 normal, Pareto, or experimental curves. Packet loss,
47 duplication, and reordering can also be emulated.
48
49 This qdisc does not do classification that can be handled in
50 layering other disciplines. It does not need to do bandwidth
51 control either since that can be handled by using token
52 bucket or other rate control.
53
54 Correlated Loss Generator models
55
56 Added generation of correlated loss according to the
57 "Gilbert-Elliot" model, a 4-state markov model.
58
59 References:
60 [1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG
61 [2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
62 and intuitive loss model for packet networks and its implementation
63 in the Netem module in the Linux kernel", available in [1]
64
65 Authors: Stefano Salsano <stefano.salsano at uniroma2.it
66 Fabio Ludovici <fabio.ludovici at yahoo.it>
67*/
68
69struct disttable {
70 u32 size;
71 s16 table[] __counted_by(size);
72};
73
74struct netem_sched_data {
75 /* internal t(ime)fifo qdisc uses t_root and sch->limit */
76 struct rb_root t_root;
77
78 /* a linear queue; reduces rbtree rebalancing when jitter is low */
79 struct sk_buff *t_head;
80 struct sk_buff *t_tail;
81
82 u32 t_len;
83
84 /* optional qdisc for classful handling (NULL at netem init) */
85 struct Qdisc *qdisc;
86
87 struct qdisc_watchdog watchdog;
88
89 s64 latency;
90 s64 jitter;
91
92 u32 loss;
93 u32 ecn;
94 u32 limit;
95 u32 counter;
96 u32 gap;
97 u32 duplicate;
98 u32 reorder;
99 u32 corrupt;
100 u64 rate;
101 s32 packet_overhead;
102 u32 cell_size;
103 struct reciprocal_value cell_size_reciprocal;
104 s32 cell_overhead;
105
106 struct crndstate {
107 u32 last;
108 u32 rho;
109 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
110
111 struct prng {
112 u64 seed;
113 struct rnd_state prng_state;
114 } prng;
115
116 struct disttable *delay_dist;
117
118 enum {
119 CLG_RANDOM,
120 CLG_4_STATES,
121 CLG_GILB_ELL,
122 } loss_model;
123
124 enum {
125 TX_IN_GAP_PERIOD = 1,
126 TX_IN_BURST_PERIOD,
127 LOST_IN_GAP_PERIOD,
128 LOST_IN_BURST_PERIOD,
129 } _4_state_model;
130
131 enum {
132 GOOD_STATE = 1,
133 BAD_STATE,
134 } GE_state_model;
135
136 /* Correlated Loss Generation models */
137 struct clgstate {
138 /* state of the Markov chain */
139 u8 state;
140
141 /* 4-states and Gilbert-Elliot models */
142 u32 a1; /* p13 for 4-states or p for GE */
143 u32 a2; /* p31 for 4-states or r for GE */
144 u32 a3; /* p32 for 4-states or h for GE */
145 u32 a4; /* p14 for 4-states or 1-k for GE */
146 u32 a5; /* p23 used only in 4-states */
147 } clg;
148
149 struct tc_netem_slot slot_config;
150 struct slotstate {
151 u64 slot_next;
152 s32 packets_left;
153 s32 bytes_left;
154 } slot;
155
156 struct disttable *slot_dist;
157};
158
159/* Time stamp put into socket buffer control block
160 * Only valid when skbs are in our internal t(ime)fifo queue.
161 *
162 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,
163 * and skb->next & skb->prev are scratch space for a qdisc,
164 * we save skb->tstamp value in skb->cb[] before destroying it.
165 */
166struct netem_skb_cb {
167 u64 time_to_send;
168};
169
170static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
171{
172 /* we assume we can use skb next/prev/tstamp as storage for rb_node */
173 qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb));
174 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
175}
176
177/* init_crandom - initialize correlated random number generator
178 * Use entropy source for initial seed.
179 */
180static void init_crandom(struct crndstate *state, unsigned long rho)
181{
182 state->rho = rho;
183 state->last = get_random_u32();
184}
185
186/* get_crandom - correlated random number generator
187 * Next number depends on last value.
188 * rho is scaled to avoid floating point.
189 */
190static u32 get_crandom(struct crndstate *state, struct prng *p)
191{
192 u64 value, rho;
193 unsigned long answer;
194 struct rnd_state *s = &p->prng_state;
195
196 if (!state || state->rho == 0) /* no correlation */
197 return prandom_u32_state(s);
198
199 value = prandom_u32_state(s);
200 rho = (u64)state->rho + 1;
201 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
202 state->last = answer;
203 return answer;
204}
205
206/* loss_4state - 4-state model loss generator
207 * Generates losses according to the 4-state Markov chain adopted in
208 * the GI (General and Intuitive) loss model.
209 */
210static bool loss_4state(struct netem_sched_data *q)
211{
212 struct clgstate *clg = &q->clg;
213 u32 rnd = prandom_u32_state(&q->prng.prng_state);
214
215 /*
216 * Makes a comparison between rnd and the transition
217 * probabilities outgoing from the current state, then decides the
218 * next state and if the next packet has to be transmitted or lost.
219 * The four states correspond to:
220 * TX_IN_GAP_PERIOD => successfully transmitted packets within a gap period
221 * LOST_IN_GAP_PERIOD => isolated losses within a gap period
222 * LOST_IN_BURST_PERIOD => lost packets within a burst period
223 * TX_IN_BURST_PERIOD => successfully transmitted packets within a burst period
224 */
225 switch (clg->state) {
226 case TX_IN_GAP_PERIOD:
227 if (rnd < clg->a4) {
228 clg->state = LOST_IN_GAP_PERIOD;
229 return true;
230 } else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {
231 clg->state = LOST_IN_BURST_PERIOD;
232 return true;
233 } else if (clg->a1 + clg->a4 < rnd) {
234 clg->state = TX_IN_GAP_PERIOD;
235 }
236
237 break;
238 case TX_IN_BURST_PERIOD:
239 if (rnd < clg->a5) {
240 clg->state = LOST_IN_BURST_PERIOD;
241 return true;
242 } else {
243 clg->state = TX_IN_BURST_PERIOD;
244 }
245
246 break;
247 case LOST_IN_BURST_PERIOD:
248 if (rnd < clg->a3)
249 clg->state = TX_IN_BURST_PERIOD;
250 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
251 clg->state = TX_IN_GAP_PERIOD;
252 } else if (clg->a2 + clg->a3 < rnd) {
253 clg->state = LOST_IN_BURST_PERIOD;
254 return true;
255 }
256 break;
257 case LOST_IN_GAP_PERIOD:
258 clg->state = TX_IN_GAP_PERIOD;
259 break;
260 }
261
262 return false;
263}
264
265/* loss_gilb_ell - Gilbert-Elliot model loss generator
266 * Generates losses according to the Gilbert-Elliot loss model or
267 * its special cases (Gilbert or Simple Gilbert)
268 *
269 * Makes a comparison between random number and the transition
270 * probabilities outgoing from the current state, then decides the
271 * next state. A second random number is extracted and the comparison
272 * with the loss probability of the current state decides if the next
273 * packet will be transmitted or lost.
274 */
275static bool loss_gilb_ell(struct netem_sched_data *q)
276{
277 struct clgstate *clg = &q->clg;
278 struct rnd_state *s = &q->prng.prng_state;
279
280 switch (clg->state) {
281 case GOOD_STATE:
282 if (prandom_u32_state(s) < clg->a1)
283 clg->state = BAD_STATE;
284 if (prandom_u32_state(s) < clg->a4)
285 return true;
286 break;
287 case BAD_STATE:
288 if (prandom_u32_state(s) < clg->a2)
289 clg->state = GOOD_STATE;
290 if (prandom_u32_state(s) > clg->a3)
291 return true;
292 }
293
294 return false;
295}
296
297static bool loss_event(struct netem_sched_data *q)
298{
299 switch (q->loss_model) {
300 case CLG_RANDOM:
301 /* Random packet drop 0 => none, ~0 => all */
302 return q->loss && q->loss >= get_crandom(&q->loss_cor, &q->prng);
303
304 case CLG_4_STATES:
305 /* 4state loss model algorithm (used also for GI model)
306 * Extracts a value from the markov 4 state loss generator,
307 * if it is 1 drops a packet and if needed writes the event in
308 * the kernel logs
309 */
310 return loss_4state(q);
311
312 case CLG_GILB_ELL:
313 /* Gilbert-Elliot loss model algorithm
314 * Extracts a value from the Gilbert-Elliot loss generator,
315 * if it is 1 drops a packet and if needed writes the event in
316 * the kernel logs
317 */
318 return loss_gilb_ell(q);
319 }
320
321 return false; /* not reached */
322}
323
324
325/* tabledist - return a pseudo-randomly distributed value with mean mu and
326 * std deviation sigma. Uses table lookup to approximate the desired
327 * distribution, and a uniformly-distributed pseudo-random source.
328 */
329static s64 tabledist(s64 mu, s32 sigma,
330 struct crndstate *state,
331 struct prng *prng,
332 const struct disttable *dist)
333{
334 s64 x;
335 long t;
336 u32 rnd;
337
338 if (sigma == 0)
339 return mu;
340
341 rnd = get_crandom(state, prng);
342
343 /* default uniform distribution */
344 if (dist == NULL)
345 return ((rnd % (2 * (u32)sigma)) + mu) - sigma;
346
347 t = dist->table[rnd % dist->size];
348 x = (sigma % NETEM_DIST_SCALE) * t;
349 if (x >= 0)
350 x += NETEM_DIST_SCALE/2;
351 else
352 x -= NETEM_DIST_SCALE/2;
353
354 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
355}
356
357static u64 packet_time_ns(u64 len, const struct netem_sched_data *q)
358{
359 len += q->packet_overhead;
360
361 if (q->cell_size) {
362 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
363
364 if (len > cells * q->cell_size) /* extra cell needed for remainder */
365 cells++;
366 len = cells * (q->cell_size + q->cell_overhead);
367 }
368
369 return div64_u64(len * NSEC_PER_SEC, q->rate);
370}
371
372static void tfifo_reset(struct Qdisc *sch)
373{
374 struct netem_sched_data *q = qdisc_priv(sch);
375 struct rb_node *p = rb_first(&q->t_root);
376
377 while (p) {
378 struct sk_buff *skb = rb_to_skb(p);
379
380 p = rb_next(p);
381 rb_erase(&skb->rbnode, &q->t_root);
382 rtnl_kfree_skbs(skb, skb);
383 }
384
385 rtnl_kfree_skbs(q->t_head, q->t_tail);
386 q->t_head = NULL;
387 q->t_tail = NULL;
388 q->t_len = 0;
389}
390
391static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
392{
393 struct netem_sched_data *q = qdisc_priv(sch);
394 u64 tnext = netem_skb_cb(nskb)->time_to_send;
395
396 if (!q->t_tail || tnext >= netem_skb_cb(q->t_tail)->time_to_send) {
397 if (q->t_tail)
398 q->t_tail->next = nskb;
399 else
400 q->t_head = nskb;
401 q->t_tail = nskb;
402 } else {
403 struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
404
405 while (*p) {
406 struct sk_buff *skb;
407
408 parent = *p;
409 skb = rb_to_skb(parent);
410 if (tnext >= netem_skb_cb(skb)->time_to_send)
411 p = &parent->rb_right;
412 else
413 p = &parent->rb_left;
414 }
415 rb_link_node(&nskb->rbnode, parent, p);
416 rb_insert_color(&nskb->rbnode, &q->t_root);
417 }
418 q->t_len++;
419 sch->q.qlen++;
420}
421
422/* netem can't properly corrupt a megapacket (like we get from GSO), so instead
423 * when we statistically choose to corrupt one, we instead segment it, returning
424 * the first packet to be corrupted, and re-enqueue the remaining frames
425 */
426static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
427 struct sk_buff **to_free)
428{
429 struct sk_buff *segs;
430 netdev_features_t features = netif_skb_features(skb);
431
432 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
433
434 if (IS_ERR_OR_NULL(segs)) {
435 qdisc_drop(skb, sch, to_free);
436 return NULL;
437 }
438 consume_skb(skb);
439 return segs;
440}
441
442/*
443 * Insert one skb into qdisc.
444 * Note: parent depends on return value to account for queue length.
445 * NET_XMIT_DROP: queue length didn't change.
446 * NET_XMIT_SUCCESS: one skb was queued.
447 */
448static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
449 struct sk_buff **to_free)
450{
451 struct netem_sched_data *q = qdisc_priv(sch);
452 /* We don't fill cb now as skb_unshare() may invalidate it */
453 struct netem_skb_cb *cb;
454 struct sk_buff *skb2 = NULL;
455 struct sk_buff *segs = NULL;
456 unsigned int prev_len = qdisc_pkt_len(skb);
457 int count = 1;
458
459 /* Do not fool qdisc_drop_all() */
460 skb->prev = NULL;
461
462 /* Random duplication */
463 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor, &q->prng))
464 ++count;
465
466 /* Drop packet? */
467 if (loss_event(q)) {
468 if (q->ecn && INET_ECN_set_ce(skb))
469 qdisc_qstats_drop(sch); /* mark packet */
470 else
471 --count;
472 }
473 if (count == 0) {
474 qdisc_qstats_drop(sch);
475 __qdisc_drop(skb, to_free);
476 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
477 }
478
479 /* If a delay is expected, orphan the skb. (orphaning usually takes
480 * place at TX completion time, so _before_ the link transit delay)
481 */
482 if (q->latency || q->jitter || q->rate)
483 skb_orphan_partial(skb);
484
485 /*
486 * If we need to duplicate packet, then clone it before
487 * original is modified.
488 */
489 if (count > 1)
490 skb2 = skb_clone(skb, GFP_ATOMIC);
491
492 /*
493 * Randomized packet corruption.
494 * Make copy if needed since we are modifying
495 * If packet is going to be hardware checksummed, then
496 * do it now in software before we mangle it.
497 */
498 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor, &q->prng)) {
499 if (skb_is_gso(skb)) {
500 skb = netem_segment(skb, sch, to_free);
501 if (!skb)
502 goto finish_segs;
503
504 segs = skb->next;
505 skb_mark_not_on_list(skb);
506 qdisc_skb_cb(skb)->pkt_len = skb->len;
507 }
508
509 skb = skb_unshare(skb, GFP_ATOMIC);
510 if (unlikely(!skb)) {
511 qdisc_qstats_drop(sch);
512 goto finish_segs;
513 }
514 if (skb->ip_summed == CHECKSUM_PARTIAL &&
515 skb_checksum_help(skb)) {
516 qdisc_drop(skb, sch, to_free);
517 skb = NULL;
518 goto finish_segs;
519 }
520
521 skb->data[get_random_u32_below(skb_headlen(skb))] ^=
522 1<<get_random_u32_below(8);
523 }
524
525 if (unlikely(q->t_len >= sch->limit)) {
526 /* re-link segs, so that qdisc_drop_all() frees them all */
527 skb->next = segs;
528 qdisc_drop_all(skb, sch, to_free);
529 if (skb2)
530 __qdisc_drop(skb2, to_free);
531 return NET_XMIT_DROP;
532 }
533
534 /*
535 * If doing duplication then re-insert at top of the
536 * qdisc tree, since parent queuer expects that only one
537 * skb will be queued.
538 */
539 if (skb2) {
540 struct Qdisc *rootq = qdisc_root_bh(sch);
541 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
542
543 q->duplicate = 0;
544 rootq->enqueue(skb2, rootq, to_free);
545 q->duplicate = dupsave;
546 skb2 = NULL;
547 }
548
549 qdisc_qstats_backlog_inc(sch, skb);
550
551 cb = netem_skb_cb(skb);
552 if (q->gap == 0 || /* not doing reordering */
553 q->counter < q->gap - 1 || /* inside last reordering gap */
554 q->reorder < get_crandom(&q->reorder_cor, &q->prng)) {
555 u64 now;
556 s64 delay;
557
558 delay = tabledist(q->latency, q->jitter,
559 &q->delay_cor, &q->prng, q->delay_dist);
560
561 now = ktime_get_ns();
562
563 if (q->rate) {
564 struct netem_skb_cb *last = NULL;
565
566 if (sch->q.tail)
567 last = netem_skb_cb(sch->q.tail);
568 if (q->t_root.rb_node) {
569 struct sk_buff *t_skb;
570 struct netem_skb_cb *t_last;
571
572 t_skb = skb_rb_last(&q->t_root);
573 t_last = netem_skb_cb(t_skb);
574 if (!last ||
575 t_last->time_to_send > last->time_to_send)
576 last = t_last;
577 }
578 if (q->t_tail) {
579 struct netem_skb_cb *t_last =
580 netem_skb_cb(q->t_tail);
581
582 if (!last ||
583 t_last->time_to_send > last->time_to_send)
584 last = t_last;
585 }
586
587 if (last) {
588 /*
589 * Last packet in queue is reference point (now),
590 * calculate this time bonus and subtract
591 * from delay.
592 */
593 delay -= last->time_to_send - now;
594 delay = max_t(s64, 0, delay);
595 now = last->time_to_send;
596 }
597
598 delay += packet_time_ns(qdisc_pkt_len(skb), q);
599 }
600
601 cb->time_to_send = now + delay;
602 ++q->counter;
603 tfifo_enqueue(skb, sch);
604 } else {
605 /*
606 * Do re-ordering by putting one out of N packets at the front
607 * of the queue.
608 */
609 cb->time_to_send = ktime_get_ns();
610 q->counter = 0;
611
612 __qdisc_enqueue_head(skb, &sch->q);
613 sch->qstats.requeues++;
614 }
615
616finish_segs:
617 if (skb2)
618 __qdisc_drop(skb2, to_free);
619
620 if (segs) {
621 unsigned int len, last_len;
622 int rc, nb;
623
624 len = skb ? skb->len : 0;
625 nb = skb ? 1 : 0;
626
627 while (segs) {
628 skb2 = segs->next;
629 skb_mark_not_on_list(segs);
630 qdisc_skb_cb(segs)->pkt_len = segs->len;
631 last_len = segs->len;
632 rc = qdisc_enqueue(segs, sch, to_free);
633 if (rc != NET_XMIT_SUCCESS) {
634 if (net_xmit_drop_count(rc))
635 qdisc_qstats_drop(sch);
636 } else {
637 nb++;
638 len += last_len;
639 }
640 segs = skb2;
641 }
642 /* Parent qdiscs accounted for 1 skb of size @prev_len */
643 qdisc_tree_reduce_backlog(sch, -(nb - 1), -(len - prev_len));
644 } else if (!skb) {
645 return NET_XMIT_DROP;
646 }
647 return NET_XMIT_SUCCESS;
648}
649
650/* Delay the next round with a new future slot with a
651 * correct number of bytes and packets.
652 */
653
654static void get_slot_next(struct netem_sched_data *q, u64 now)
655{
656 s64 next_delay;
657
658 if (!q->slot_dist)
659 next_delay = q->slot_config.min_delay +
660 (get_random_u32() *
661 (q->slot_config.max_delay -
662 q->slot_config.min_delay) >> 32);
663 else
664 next_delay = tabledist(q->slot_config.dist_delay,
665 (s32)(q->slot_config.dist_jitter),
666 NULL, &q->prng, q->slot_dist);
667
668 q->slot.slot_next = now + next_delay;
669 q->slot.packets_left = q->slot_config.max_packets;
670 q->slot.bytes_left = q->slot_config.max_bytes;
671}
672
673static struct sk_buff *netem_peek(struct netem_sched_data *q)
674{
675 struct sk_buff *skb = skb_rb_first(&q->t_root);
676 u64 t1, t2;
677
678 if (!skb)
679 return q->t_head;
680 if (!q->t_head)
681 return skb;
682
683 t1 = netem_skb_cb(skb)->time_to_send;
684 t2 = netem_skb_cb(q->t_head)->time_to_send;
685 if (t1 < t2)
686 return skb;
687 return q->t_head;
688}
689
690static void netem_erase_head(struct netem_sched_data *q, struct sk_buff *skb)
691{
692 if (skb == q->t_head) {
693 q->t_head = skb->next;
694 if (!q->t_head)
695 q->t_tail = NULL;
696 } else {
697 rb_erase(&skb->rbnode, &q->t_root);
698 }
699}
700
701static struct sk_buff *netem_dequeue(struct Qdisc *sch)
702{
703 struct netem_sched_data *q = qdisc_priv(sch);
704 struct sk_buff *skb;
705
706tfifo_dequeue:
707 skb = __qdisc_dequeue_head(&sch->q);
708 if (skb) {
709deliver:
710 qdisc_qstats_backlog_dec(sch, skb);
711 qdisc_bstats_update(sch, skb);
712 return skb;
713 }
714 skb = netem_peek(q);
715 if (skb) {
716 u64 time_to_send;
717 u64 now = ktime_get_ns();
718
719 /* if more time remaining? */
720 time_to_send = netem_skb_cb(skb)->time_to_send;
721 if (q->slot.slot_next && q->slot.slot_next < time_to_send)
722 get_slot_next(q, now);
723
724 if (time_to_send <= now && q->slot.slot_next <= now) {
725 netem_erase_head(q, skb);
726 q->t_len--;
727 skb->next = NULL;
728 skb->prev = NULL;
729 /* skb->dev shares skb->rbnode area,
730 * we need to restore its value.
731 */
732 skb->dev = qdisc_dev(sch);
733
734 if (q->slot.slot_next) {
735 q->slot.packets_left--;
736 q->slot.bytes_left -= qdisc_pkt_len(skb);
737 if (q->slot.packets_left <= 0 ||
738 q->slot.bytes_left <= 0)
739 get_slot_next(q, now);
740 }
741
742 if (q->qdisc) {
743 unsigned int pkt_len = qdisc_pkt_len(skb);
744 struct sk_buff *to_free = NULL;
745 int err;
746
747 err = qdisc_enqueue(skb, q->qdisc, &to_free);
748 kfree_skb_list(to_free);
749 if (err != NET_XMIT_SUCCESS) {
750 if (net_xmit_drop_count(err))
751 qdisc_qstats_drop(sch);
752 sch->qstats.backlog -= pkt_len;
753 sch->q.qlen--;
754 qdisc_tree_reduce_backlog(sch, 1, pkt_len);
755 }
756 goto tfifo_dequeue;
757 }
758 sch->q.qlen--;
759 goto deliver;
760 }
761
762 if (q->qdisc) {
763 skb = q->qdisc->ops->dequeue(q->qdisc);
764 if (skb) {
765 sch->q.qlen--;
766 goto deliver;
767 }
768 }
769
770 qdisc_watchdog_schedule_ns(&q->watchdog,
771 max(time_to_send,
772 q->slot.slot_next));
773 }
774
775 if (q->qdisc) {
776 skb = q->qdisc->ops->dequeue(q->qdisc);
777 if (skb) {
778 sch->q.qlen--;
779 goto deliver;
780 }
781 }
782 return NULL;
783}
784
785static void netem_reset(struct Qdisc *sch)
786{
787 struct netem_sched_data *q = qdisc_priv(sch);
788
789 qdisc_reset_queue(sch);
790 tfifo_reset(sch);
791 if (q->qdisc)
792 qdisc_reset(q->qdisc);
793 qdisc_watchdog_cancel(&q->watchdog);
794}
795
796static void dist_free(struct disttable *d)
797{
798 kvfree(d);
799}
800
801/*
802 * Distribution data is a variable size payload containing
803 * signed 16 bit values.
804 */
805
806static int get_dist_table(struct disttable **tbl, const struct nlattr *attr)
807{
808 size_t n = nla_len(attr)/sizeof(__s16);
809 const __s16 *data = nla_data(attr);
810 struct disttable *d;
811 int i;
812
813 if (!n || n > NETEM_DIST_MAX)
814 return -EINVAL;
815
816 d = kvmalloc(struct_size(d, table, n), GFP_KERNEL);
817 if (!d)
818 return -ENOMEM;
819
820 d->size = n;
821 for (i = 0; i < n; i++)
822 d->table[i] = data[i];
823
824 *tbl = d;
825 return 0;
826}
827
828static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
829{
830 const struct tc_netem_slot *c = nla_data(attr);
831
832 q->slot_config = *c;
833 if (q->slot_config.max_packets == 0)
834 q->slot_config.max_packets = INT_MAX;
835 if (q->slot_config.max_bytes == 0)
836 q->slot_config.max_bytes = INT_MAX;
837
838 /* capping dist_jitter to the range acceptable by tabledist() */
839 q->slot_config.dist_jitter = min_t(__s64, INT_MAX, abs(q->slot_config.dist_jitter));
840
841 q->slot.packets_left = q->slot_config.max_packets;
842 q->slot.bytes_left = q->slot_config.max_bytes;
843 if (q->slot_config.min_delay | q->slot_config.max_delay |
844 q->slot_config.dist_jitter)
845 q->slot.slot_next = ktime_get_ns();
846 else
847 q->slot.slot_next = 0;
848}
849
850static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
851{
852 const struct tc_netem_corr *c = nla_data(attr);
853
854 init_crandom(&q->delay_cor, c->delay_corr);
855 init_crandom(&q->loss_cor, c->loss_corr);
856 init_crandom(&q->dup_cor, c->dup_corr);
857}
858
859static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
860{
861 const struct tc_netem_reorder *r = nla_data(attr);
862
863 q->reorder = r->probability;
864 init_crandom(&q->reorder_cor, r->correlation);
865}
866
867static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
868{
869 const struct tc_netem_corrupt *r = nla_data(attr);
870
871 q->corrupt = r->probability;
872 init_crandom(&q->corrupt_cor, r->correlation);
873}
874
875static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
876{
877 const struct tc_netem_rate *r = nla_data(attr);
878
879 q->rate = r->rate;
880 q->packet_overhead = r->packet_overhead;
881 q->cell_size = r->cell_size;
882 q->cell_overhead = r->cell_overhead;
883 if (q->cell_size)
884 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
885 else
886 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
887}
888
889static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
890{
891 const struct nlattr *la;
892 int rem;
893
894 nla_for_each_nested(la, attr, rem) {
895 u16 type = nla_type(la);
896
897 switch (type) {
898 case NETEM_LOSS_GI: {
899 const struct tc_netem_gimodel *gi = nla_data(la);
900
901 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
902 pr_info("netem: incorrect gi model size\n");
903 return -EINVAL;
904 }
905
906 q->loss_model = CLG_4_STATES;
907
908 q->clg.state = TX_IN_GAP_PERIOD;
909 q->clg.a1 = gi->p13;
910 q->clg.a2 = gi->p31;
911 q->clg.a3 = gi->p32;
912 q->clg.a4 = gi->p14;
913 q->clg.a5 = gi->p23;
914 break;
915 }
916
917 case NETEM_LOSS_GE: {
918 const struct tc_netem_gemodel *ge = nla_data(la);
919
920 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
921 pr_info("netem: incorrect ge model size\n");
922 return -EINVAL;
923 }
924
925 q->loss_model = CLG_GILB_ELL;
926 q->clg.state = GOOD_STATE;
927 q->clg.a1 = ge->p;
928 q->clg.a2 = ge->r;
929 q->clg.a3 = ge->h;
930 q->clg.a4 = ge->k1;
931 break;
932 }
933
934 default:
935 pr_info("netem: unknown loss type %u\n", type);
936 return -EINVAL;
937 }
938 }
939
940 return 0;
941}
942
943static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
944 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
945 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
946 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
947 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
948 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
949 [TCA_NETEM_ECN] = { .type = NLA_U32 },
950 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
951 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
952 [TCA_NETEM_JITTER64] = { .type = NLA_S64 },
953 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
954 [TCA_NETEM_PRNG_SEED] = { .type = NLA_U64 },
955};
956
957static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
958 const struct nla_policy *policy, int len)
959{
960 int nested_len = nla_len(nla) - NLA_ALIGN(len);
961
962 if (nested_len < 0) {
963 pr_info("netem: invalid attributes len %d\n", nested_len);
964 return -EINVAL;
965 }
966
967 if (nested_len >= nla_attr_size(0))
968 return nla_parse_deprecated(tb, maxtype,
969 nla_data(nla) + NLA_ALIGN(len),
970 nested_len, policy, NULL);
971
972 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
973 return 0;
974}
975
976/* Parse netlink message to set options */
977static int netem_change(struct Qdisc *sch, struct nlattr *opt,
978 struct netlink_ext_ack *extack)
979{
980 struct netem_sched_data *q = qdisc_priv(sch);
981 struct nlattr *tb[TCA_NETEM_MAX + 1];
982 struct disttable *delay_dist = NULL;
983 struct disttable *slot_dist = NULL;
984 struct tc_netem_qopt *qopt;
985 struct clgstate old_clg;
986 int old_loss_model = CLG_RANDOM;
987 int ret;
988
989 qopt = nla_data(opt);
990 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
991 if (ret < 0)
992 return ret;
993
994 if (tb[TCA_NETEM_DELAY_DIST]) {
995 ret = get_dist_table(&delay_dist, tb[TCA_NETEM_DELAY_DIST]);
996 if (ret)
997 goto table_free;
998 }
999
1000 if (tb[TCA_NETEM_SLOT_DIST]) {
1001 ret = get_dist_table(&slot_dist, tb[TCA_NETEM_SLOT_DIST]);
1002 if (ret)
1003 goto table_free;
1004 }
1005
1006 sch_tree_lock(sch);
1007 /* backup q->clg and q->loss_model */
1008 old_clg = q->clg;
1009 old_loss_model = q->loss_model;
1010
1011 if (tb[TCA_NETEM_LOSS]) {
1012 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
1013 if (ret) {
1014 q->loss_model = old_loss_model;
1015 q->clg = old_clg;
1016 goto unlock;
1017 }
1018 } else {
1019 q->loss_model = CLG_RANDOM;
1020 }
1021
1022 if (delay_dist)
1023 swap(q->delay_dist, delay_dist);
1024 if (slot_dist)
1025 swap(q->slot_dist, slot_dist);
1026 sch->limit = qopt->limit;
1027
1028 q->latency = PSCHED_TICKS2NS(qopt->latency);
1029 q->jitter = PSCHED_TICKS2NS(qopt->jitter);
1030 q->limit = qopt->limit;
1031 q->gap = qopt->gap;
1032 q->counter = 0;
1033 q->loss = qopt->loss;
1034 q->duplicate = qopt->duplicate;
1035
1036 /* for compatibility with earlier versions.
1037 * if gap is set, need to assume 100% probability
1038 */
1039 if (q->gap)
1040 q->reorder = ~0;
1041
1042 if (tb[TCA_NETEM_CORR])
1043 get_correlation(q, tb[TCA_NETEM_CORR]);
1044
1045 if (tb[TCA_NETEM_REORDER])
1046 get_reorder(q, tb[TCA_NETEM_REORDER]);
1047
1048 if (tb[TCA_NETEM_CORRUPT])
1049 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
1050
1051 if (tb[TCA_NETEM_RATE])
1052 get_rate(q, tb[TCA_NETEM_RATE]);
1053
1054 if (tb[TCA_NETEM_RATE64])
1055 q->rate = max_t(u64, q->rate,
1056 nla_get_u64(tb[TCA_NETEM_RATE64]));
1057
1058 if (tb[TCA_NETEM_LATENCY64])
1059 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
1060
1061 if (tb[TCA_NETEM_JITTER64])
1062 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
1063
1064 if (tb[TCA_NETEM_ECN])
1065 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
1066
1067 if (tb[TCA_NETEM_SLOT])
1068 get_slot(q, tb[TCA_NETEM_SLOT]);
1069
1070 /* capping jitter to the range acceptable by tabledist() */
1071 q->jitter = min_t(s64, abs(q->jitter), INT_MAX);
1072
1073 if (tb[TCA_NETEM_PRNG_SEED])
1074 q->prng.seed = nla_get_u64(tb[TCA_NETEM_PRNG_SEED]);
1075 else
1076 q->prng.seed = get_random_u64();
1077 prandom_seed_state(&q->prng.prng_state, q->prng.seed);
1078
1079unlock:
1080 sch_tree_unlock(sch);
1081
1082table_free:
1083 dist_free(delay_dist);
1084 dist_free(slot_dist);
1085 return ret;
1086}
1087
1088static int netem_init(struct Qdisc *sch, struct nlattr *opt,
1089 struct netlink_ext_ack *extack)
1090{
1091 struct netem_sched_data *q = qdisc_priv(sch);
1092 int ret;
1093
1094 qdisc_watchdog_init(&q->watchdog, sch);
1095
1096 if (!opt)
1097 return -EINVAL;
1098
1099 q->loss_model = CLG_RANDOM;
1100 ret = netem_change(sch, opt, extack);
1101 if (ret)
1102 pr_info("netem: change failed\n");
1103 return ret;
1104}
1105
1106static void netem_destroy(struct Qdisc *sch)
1107{
1108 struct netem_sched_data *q = qdisc_priv(sch);
1109
1110 qdisc_watchdog_cancel(&q->watchdog);
1111 if (q->qdisc)
1112 qdisc_put(q->qdisc);
1113 dist_free(q->delay_dist);
1114 dist_free(q->slot_dist);
1115}
1116
1117static int dump_loss_model(const struct netem_sched_data *q,
1118 struct sk_buff *skb)
1119{
1120 struct nlattr *nest;
1121
1122 nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS);
1123 if (nest == NULL)
1124 goto nla_put_failure;
1125
1126 switch (q->loss_model) {
1127 case CLG_RANDOM:
1128 /* legacy loss model */
1129 nla_nest_cancel(skb, nest);
1130 return 0; /* no data */
1131
1132 case CLG_4_STATES: {
1133 struct tc_netem_gimodel gi = {
1134 .p13 = q->clg.a1,
1135 .p31 = q->clg.a2,
1136 .p32 = q->clg.a3,
1137 .p14 = q->clg.a4,
1138 .p23 = q->clg.a5,
1139 };
1140
1141 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
1142 goto nla_put_failure;
1143 break;
1144 }
1145 case CLG_GILB_ELL: {
1146 struct tc_netem_gemodel ge = {
1147 .p = q->clg.a1,
1148 .r = q->clg.a2,
1149 .h = q->clg.a3,
1150 .k1 = q->clg.a4,
1151 };
1152
1153 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1154 goto nla_put_failure;
1155 break;
1156 }
1157 }
1158
1159 nla_nest_end(skb, nest);
1160 return 0;
1161
1162nla_put_failure:
1163 nla_nest_cancel(skb, nest);
1164 return -1;
1165}
1166
1167static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1168{
1169 const struct netem_sched_data *q = qdisc_priv(sch);
1170 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1171 struct tc_netem_qopt qopt;
1172 struct tc_netem_corr cor;
1173 struct tc_netem_reorder reorder;
1174 struct tc_netem_corrupt corrupt;
1175 struct tc_netem_rate rate;
1176 struct tc_netem_slot slot;
1177
1178 qopt.latency = min_t(psched_time_t, PSCHED_NS2TICKS(q->latency),
1179 UINT_MAX);
1180 qopt.jitter = min_t(psched_time_t, PSCHED_NS2TICKS(q->jitter),
1181 UINT_MAX);
1182 qopt.limit = q->limit;
1183 qopt.loss = q->loss;
1184 qopt.gap = q->gap;
1185 qopt.duplicate = q->duplicate;
1186 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1187 goto nla_put_failure;
1188
1189 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
1190 goto nla_put_failure;
1191
1192 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
1193 goto nla_put_failure;
1194
1195 cor.delay_corr = q->delay_cor.rho;
1196 cor.loss_corr = q->loss_cor.rho;
1197 cor.dup_corr = q->dup_cor.rho;
1198 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1199 goto nla_put_failure;
1200
1201 reorder.probability = q->reorder;
1202 reorder.correlation = q->reorder_cor.rho;
1203 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1204 goto nla_put_failure;
1205
1206 corrupt.probability = q->corrupt;
1207 corrupt.correlation = q->corrupt_cor.rho;
1208 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1209 goto nla_put_failure;
1210
1211 if (q->rate >= (1ULL << 32)) {
1212 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1213 TCA_NETEM_PAD))
1214 goto nla_put_failure;
1215 rate.rate = ~0U;
1216 } else {
1217 rate.rate = q->rate;
1218 }
1219 rate.packet_overhead = q->packet_overhead;
1220 rate.cell_size = q->cell_size;
1221 rate.cell_overhead = q->cell_overhead;
1222 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1223 goto nla_put_failure;
1224
1225 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1226 goto nla_put_failure;
1227
1228 if (dump_loss_model(q, skb) != 0)
1229 goto nla_put_failure;
1230
1231 if (q->slot_config.min_delay | q->slot_config.max_delay |
1232 q->slot_config.dist_jitter) {
1233 slot = q->slot_config;
1234 if (slot.max_packets == INT_MAX)
1235 slot.max_packets = 0;
1236 if (slot.max_bytes == INT_MAX)
1237 slot.max_bytes = 0;
1238 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
1239 goto nla_put_failure;
1240 }
1241
1242 if (nla_put_u64_64bit(skb, TCA_NETEM_PRNG_SEED, q->prng.seed,
1243 TCA_NETEM_PAD))
1244 goto nla_put_failure;
1245
1246 return nla_nest_end(skb, nla);
1247
1248nla_put_failure:
1249 nlmsg_trim(skb, nla);
1250 return -1;
1251}
1252
1253static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1254 struct sk_buff *skb, struct tcmsg *tcm)
1255{
1256 struct netem_sched_data *q = qdisc_priv(sch);
1257
1258 if (cl != 1 || !q->qdisc) /* only one class */
1259 return -ENOENT;
1260
1261 tcm->tcm_handle |= TC_H_MIN(1);
1262 tcm->tcm_info = q->qdisc->handle;
1263
1264 return 0;
1265}
1266
1267static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1268 struct Qdisc **old, struct netlink_ext_ack *extack)
1269{
1270 struct netem_sched_data *q = qdisc_priv(sch);
1271
1272 *old = qdisc_replace(sch, new, &q->qdisc);
1273 return 0;
1274}
1275
1276static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1277{
1278 struct netem_sched_data *q = qdisc_priv(sch);
1279 return q->qdisc;
1280}
1281
1282static unsigned long netem_find(struct Qdisc *sch, u32 classid)
1283{
1284 return 1;
1285}
1286
1287static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1288{
1289 if (!walker->stop) {
1290 if (!tc_qdisc_stats_dump(sch, 1, walker))
1291 return;
1292 }
1293}
1294
1295static const struct Qdisc_class_ops netem_class_ops = {
1296 .graft = netem_graft,
1297 .leaf = netem_leaf,
1298 .find = netem_find,
1299 .walk = netem_walk,
1300 .dump = netem_dump_class,
1301};
1302
1303static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1304 .id = "netem",
1305 .cl_ops = &netem_class_ops,
1306 .priv_size = sizeof(struct netem_sched_data),
1307 .enqueue = netem_enqueue,
1308 .dequeue = netem_dequeue,
1309 .peek = qdisc_peek_dequeued,
1310 .init = netem_init,
1311 .reset = netem_reset,
1312 .destroy = netem_destroy,
1313 .change = netem_change,
1314 .dump = netem_dump,
1315 .owner = THIS_MODULE,
1316};
1317MODULE_ALIAS_NET_SCH("netem");
1318
1319
1320static int __init netem_module_init(void)
1321{
1322 pr_info("netem: version " VERSION "\n");
1323 return register_qdisc(&netem_qdisc_ops);
1324}
1325static void __exit netem_module_exit(void)
1326{
1327 unregister_qdisc(&netem_qdisc_ops);
1328}
1329module_init(netem_module_init)
1330module_exit(netem_module_exit)
1331MODULE_LICENSE("GPL");
1332MODULE_DESCRIPTION("Network characteristics emulator qdisc");
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
26#include <net/netlink.h>
27#include <net/pkt_sched.h>
28
29#define VERSION "1.3"
30
31/* Network Emulation Queuing algorithm.
32 ====================================
33
34 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
35 Network Emulation Tool
36 [2] Luigi Rizzo, DummyNet for FreeBSD
37
38 ----------------------------------------------------------------
39
40 This started out as a simple way to delay outgoing packets to
41 test TCP but has grown to include most of the functionality
42 of a full blown network emulator like NISTnet. It can delay
43 packets and add random jitter (and correlation). The random
44 distribution can be loaded from a table as well to provide
45 normal, Pareto, or experimental curves. Packet loss,
46 duplication, and reordering can also be emulated.
47
48 This qdisc does not do classification that can be handled in
49 layering other disciplines. It does not need to do bandwidth
50 control either since that can be handled by using token
51 bucket or other rate control.
52
53 Correlated Loss Generator models
54
55 Added generation of correlated loss according to the
56 "Gilbert-Elliot" model, a 4-state markov model.
57
58 References:
59 [1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG
60 [2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
61 and intuitive loss model for packet networks and its implementation
62 in the Netem module in the Linux kernel", available in [1]
63
64 Authors: Stefano Salsano <stefano.salsano at uniroma2.it
65 Fabio Ludovici <fabio.ludovici at yahoo.it>
66*/
67
68struct netem_sched_data {
69 struct Qdisc *qdisc;
70 struct qdisc_watchdog watchdog;
71
72 psched_tdiff_t latency;
73 psched_tdiff_t jitter;
74
75 u32 loss;
76 u32 limit;
77 u32 counter;
78 u32 gap;
79 u32 duplicate;
80 u32 reorder;
81 u32 corrupt;
82
83 struct crndstate {
84 u32 last;
85 u32 rho;
86 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
87
88 struct disttable {
89 u32 size;
90 s16 table[0];
91 } *delay_dist;
92
93 enum {
94 CLG_RANDOM,
95 CLG_4_STATES,
96 CLG_GILB_ELL,
97 } loss_model;
98
99 /* Correlated Loss Generation models */
100 struct clgstate {
101 /* state of the Markov chain */
102 u8 state;
103
104 /* 4-states and Gilbert-Elliot models */
105 u32 a1; /* p13 for 4-states or p for GE */
106 u32 a2; /* p31 for 4-states or r for GE */
107 u32 a3; /* p32 for 4-states or h for GE */
108 u32 a4; /* p14 for 4-states or 1-k for GE */
109 u32 a5; /* p23 used only in 4-states */
110 } clg;
111
112};
113
114/* Time stamp put into socket buffer control block */
115struct netem_skb_cb {
116 psched_time_t time_to_send;
117};
118
119static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
120{
121 BUILD_BUG_ON(sizeof(skb->cb) <
122 sizeof(struct qdisc_skb_cb) + sizeof(struct netem_skb_cb));
123 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
124}
125
126/* init_crandom - initialize correlated random number generator
127 * Use entropy source for initial seed.
128 */
129static void init_crandom(struct crndstate *state, unsigned long rho)
130{
131 state->rho = rho;
132 state->last = net_random();
133}
134
135/* get_crandom - correlated random number generator
136 * Next number depends on last value.
137 * rho is scaled to avoid floating point.
138 */
139static u32 get_crandom(struct crndstate *state)
140{
141 u64 value, rho;
142 unsigned long answer;
143
144 if (state->rho == 0) /* no correlation */
145 return net_random();
146
147 value = net_random();
148 rho = (u64)state->rho + 1;
149 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
150 state->last = answer;
151 return answer;
152}
153
154/* loss_4state - 4-state model loss generator
155 * Generates losses according to the 4-state Markov chain adopted in
156 * the GI (General and Intuitive) loss model.
157 */
158static bool loss_4state(struct netem_sched_data *q)
159{
160 struct clgstate *clg = &q->clg;
161 u32 rnd = net_random();
162
163 /*
164 * Makes a comparison between rnd and the transition
165 * probabilities outgoing from the current state, then decides the
166 * next state and if the next packet has to be transmitted or lost.
167 * The four states correspond to:
168 * 1 => successfully transmitted packets within a gap period
169 * 4 => isolated losses within a gap period
170 * 3 => lost packets within a burst period
171 * 2 => successfully transmitted packets within a burst period
172 */
173 switch (clg->state) {
174 case 1:
175 if (rnd < clg->a4) {
176 clg->state = 4;
177 return true;
178 } else if (clg->a4 < rnd && rnd < clg->a1) {
179 clg->state = 3;
180 return true;
181 } else if (clg->a1 < rnd)
182 clg->state = 1;
183
184 break;
185 case 2:
186 if (rnd < clg->a5) {
187 clg->state = 3;
188 return true;
189 } else
190 clg->state = 2;
191
192 break;
193 case 3:
194 if (rnd < clg->a3)
195 clg->state = 2;
196 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
197 clg->state = 1;
198 return true;
199 } else if (clg->a2 + clg->a3 < rnd) {
200 clg->state = 3;
201 return true;
202 }
203 break;
204 case 4:
205 clg->state = 1;
206 break;
207 }
208
209 return false;
210}
211
212/* loss_gilb_ell - Gilbert-Elliot model loss generator
213 * Generates losses according to the Gilbert-Elliot loss model or
214 * its special cases (Gilbert or Simple Gilbert)
215 *
216 * Makes a comparison between random number and the transition
217 * probabilities outgoing from the current state, then decides the
218 * next state. A second random number is extracted and the comparison
219 * with the loss probability of the current state decides if the next
220 * packet will be transmitted or lost.
221 */
222static bool loss_gilb_ell(struct netem_sched_data *q)
223{
224 struct clgstate *clg = &q->clg;
225
226 switch (clg->state) {
227 case 1:
228 if (net_random() < clg->a1)
229 clg->state = 2;
230 if (net_random() < clg->a4)
231 return true;
232 case 2:
233 if (net_random() < clg->a2)
234 clg->state = 1;
235 if (clg->a3 > net_random())
236 return true;
237 }
238
239 return false;
240}
241
242static bool loss_event(struct netem_sched_data *q)
243{
244 switch (q->loss_model) {
245 case CLG_RANDOM:
246 /* Random packet drop 0 => none, ~0 => all */
247 return q->loss && q->loss >= get_crandom(&q->loss_cor);
248
249 case CLG_4_STATES:
250 /* 4state loss model algorithm (used also for GI model)
251 * Extracts a value from the markov 4 state loss generator,
252 * if it is 1 drops a packet and if needed writes the event in
253 * the kernel logs
254 */
255 return loss_4state(q);
256
257 case CLG_GILB_ELL:
258 /* Gilbert-Elliot loss model algorithm
259 * Extracts a value from the Gilbert-Elliot loss generator,
260 * if it is 1 drops a packet and if needed writes the event in
261 * the kernel logs
262 */
263 return loss_gilb_ell(q);
264 }
265
266 return false; /* not reached */
267}
268
269
270/* tabledist - return a pseudo-randomly distributed value with mean mu and
271 * std deviation sigma. Uses table lookup to approximate the desired
272 * distribution, and a uniformly-distributed pseudo-random source.
273 */
274static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
275 struct crndstate *state,
276 const struct disttable *dist)
277{
278 psched_tdiff_t x;
279 long t;
280 u32 rnd;
281
282 if (sigma == 0)
283 return mu;
284
285 rnd = get_crandom(state);
286
287 /* default uniform distribution */
288 if (dist == NULL)
289 return (rnd % (2*sigma)) - sigma + mu;
290
291 t = dist->table[rnd % dist->size];
292 x = (sigma % NETEM_DIST_SCALE) * t;
293 if (x >= 0)
294 x += NETEM_DIST_SCALE/2;
295 else
296 x -= NETEM_DIST_SCALE/2;
297
298 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
299}
300
301/*
302 * Insert one skb into qdisc.
303 * Note: parent depends on return value to account for queue length.
304 * NET_XMIT_DROP: queue length didn't change.
305 * NET_XMIT_SUCCESS: one skb was queued.
306 */
307static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
308{
309 struct netem_sched_data *q = qdisc_priv(sch);
310 /* We don't fill cb now as skb_unshare() may invalidate it */
311 struct netem_skb_cb *cb;
312 struct sk_buff *skb2;
313 int ret;
314 int count = 1;
315
316 /* Random duplication */
317 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
318 ++count;
319
320 /* Drop packet? */
321 if (loss_event(q))
322 --count;
323
324 if (count == 0) {
325 sch->qstats.drops++;
326 kfree_skb(skb);
327 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
328 }
329
330 skb_orphan(skb);
331
332 /*
333 * If we need to duplicate packet, then re-insert at top of the
334 * qdisc tree, since parent queuer expects that only one
335 * skb will be queued.
336 */
337 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
338 struct Qdisc *rootq = qdisc_root(sch);
339 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
340 q->duplicate = 0;
341
342 qdisc_enqueue_root(skb2, rootq);
343 q->duplicate = dupsave;
344 }
345
346 /*
347 * Randomized packet corruption.
348 * Make copy if needed since we are modifying
349 * If packet is going to be hardware checksummed, then
350 * do it now in software before we mangle it.
351 */
352 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
353 if (!(skb = skb_unshare(skb, GFP_ATOMIC)) ||
354 (skb->ip_summed == CHECKSUM_PARTIAL &&
355 skb_checksum_help(skb))) {
356 sch->qstats.drops++;
357 return NET_XMIT_DROP;
358 }
359
360 skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
361 }
362
363 cb = netem_skb_cb(skb);
364 if (q->gap == 0 || /* not doing reordering */
365 q->counter < q->gap || /* inside last reordering gap */
366 q->reorder < get_crandom(&q->reorder_cor)) {
367 psched_time_t now;
368 psched_tdiff_t delay;
369
370 delay = tabledist(q->latency, q->jitter,
371 &q->delay_cor, q->delay_dist);
372
373 now = psched_get_time();
374 cb->time_to_send = now + delay;
375 ++q->counter;
376 ret = qdisc_enqueue(skb, q->qdisc);
377 } else {
378 /*
379 * Do re-ordering by putting one out of N packets at the front
380 * of the queue.
381 */
382 cb->time_to_send = psched_get_time();
383 q->counter = 0;
384
385 __skb_queue_head(&q->qdisc->q, skb);
386 q->qdisc->qstats.backlog += qdisc_pkt_len(skb);
387 q->qdisc->qstats.requeues++;
388 ret = NET_XMIT_SUCCESS;
389 }
390
391 if (ret != NET_XMIT_SUCCESS) {
392 if (net_xmit_drop_count(ret)) {
393 sch->qstats.drops++;
394 return ret;
395 }
396 }
397
398 sch->q.qlen++;
399 return NET_XMIT_SUCCESS;
400}
401
402static unsigned int netem_drop(struct Qdisc *sch)
403{
404 struct netem_sched_data *q = qdisc_priv(sch);
405 unsigned int len = 0;
406
407 if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
408 sch->q.qlen--;
409 sch->qstats.drops++;
410 }
411 return len;
412}
413
414static struct sk_buff *netem_dequeue(struct Qdisc *sch)
415{
416 struct netem_sched_data *q = qdisc_priv(sch);
417 struct sk_buff *skb;
418
419 if (qdisc_is_throttled(sch))
420 return NULL;
421
422 skb = q->qdisc->ops->peek(q->qdisc);
423 if (skb) {
424 const struct netem_skb_cb *cb = netem_skb_cb(skb);
425 psched_time_t now = psched_get_time();
426
427 /* if more time remaining? */
428 if (cb->time_to_send <= now) {
429 skb = qdisc_dequeue_peeked(q->qdisc);
430 if (unlikely(!skb))
431 return NULL;
432
433#ifdef CONFIG_NET_CLS_ACT
434 /*
435 * If it's at ingress let's pretend the delay is
436 * from the network (tstamp will be updated).
437 */
438 if (G_TC_FROM(skb->tc_verd) & AT_INGRESS)
439 skb->tstamp.tv64 = 0;
440#endif
441
442 sch->q.qlen--;
443 qdisc_unthrottled(sch);
444 qdisc_bstats_update(sch, skb);
445 return skb;
446 }
447
448 qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
449 }
450
451 return NULL;
452}
453
454static void netem_reset(struct Qdisc *sch)
455{
456 struct netem_sched_data *q = qdisc_priv(sch);
457
458 qdisc_reset(q->qdisc);
459 sch->q.qlen = 0;
460 qdisc_watchdog_cancel(&q->watchdog);
461}
462
463static void dist_free(struct disttable *d)
464{
465 if (d) {
466 if (is_vmalloc_addr(d))
467 vfree(d);
468 else
469 kfree(d);
470 }
471}
472
473/*
474 * Distribution data is a variable size payload containing
475 * signed 16 bit values.
476 */
477static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
478{
479 struct netem_sched_data *q = qdisc_priv(sch);
480 size_t n = nla_len(attr)/sizeof(__s16);
481 const __s16 *data = nla_data(attr);
482 spinlock_t *root_lock;
483 struct disttable *d;
484 int i;
485 size_t s;
486
487 if (n > NETEM_DIST_MAX)
488 return -EINVAL;
489
490 s = sizeof(struct disttable) + n * sizeof(s16);
491 d = kmalloc(s, GFP_KERNEL);
492 if (!d)
493 d = vmalloc(s);
494 if (!d)
495 return -ENOMEM;
496
497 d->size = n;
498 for (i = 0; i < n; i++)
499 d->table[i] = data[i];
500
501 root_lock = qdisc_root_sleeping_lock(sch);
502
503 spin_lock_bh(root_lock);
504 dist_free(q->delay_dist);
505 q->delay_dist = d;
506 spin_unlock_bh(root_lock);
507 return 0;
508}
509
510static void get_correlation(struct Qdisc *sch, const struct nlattr *attr)
511{
512 struct netem_sched_data *q = qdisc_priv(sch);
513 const struct tc_netem_corr *c = nla_data(attr);
514
515 init_crandom(&q->delay_cor, c->delay_corr);
516 init_crandom(&q->loss_cor, c->loss_corr);
517 init_crandom(&q->dup_cor, c->dup_corr);
518}
519
520static void get_reorder(struct Qdisc *sch, const struct nlattr *attr)
521{
522 struct netem_sched_data *q = qdisc_priv(sch);
523 const struct tc_netem_reorder *r = nla_data(attr);
524
525 q->reorder = r->probability;
526 init_crandom(&q->reorder_cor, r->correlation);
527}
528
529static void get_corrupt(struct Qdisc *sch, const struct nlattr *attr)
530{
531 struct netem_sched_data *q = qdisc_priv(sch);
532 const struct tc_netem_corrupt *r = nla_data(attr);
533
534 q->corrupt = r->probability;
535 init_crandom(&q->corrupt_cor, r->correlation);
536}
537
538static int get_loss_clg(struct Qdisc *sch, const struct nlattr *attr)
539{
540 struct netem_sched_data *q = qdisc_priv(sch);
541 const struct nlattr *la;
542 int rem;
543
544 nla_for_each_nested(la, attr, rem) {
545 u16 type = nla_type(la);
546
547 switch(type) {
548 case NETEM_LOSS_GI: {
549 const struct tc_netem_gimodel *gi = nla_data(la);
550
551 if (nla_len(la) != sizeof(struct tc_netem_gimodel)) {
552 pr_info("netem: incorrect gi model size\n");
553 return -EINVAL;
554 }
555
556 q->loss_model = CLG_4_STATES;
557
558 q->clg.state = 1;
559 q->clg.a1 = gi->p13;
560 q->clg.a2 = gi->p31;
561 q->clg.a3 = gi->p32;
562 q->clg.a4 = gi->p14;
563 q->clg.a5 = gi->p23;
564 break;
565 }
566
567 case NETEM_LOSS_GE: {
568 const struct tc_netem_gemodel *ge = nla_data(la);
569
570 if (nla_len(la) != sizeof(struct tc_netem_gemodel)) {
571 pr_info("netem: incorrect gi model size\n");
572 return -EINVAL;
573 }
574
575 q->loss_model = CLG_GILB_ELL;
576 q->clg.state = 1;
577 q->clg.a1 = ge->p;
578 q->clg.a2 = ge->r;
579 q->clg.a3 = ge->h;
580 q->clg.a4 = ge->k1;
581 break;
582 }
583
584 default:
585 pr_info("netem: unknown loss type %u\n", type);
586 return -EINVAL;
587 }
588 }
589
590 return 0;
591}
592
593static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
594 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
595 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
596 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
597 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
598};
599
600static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
601 const struct nla_policy *policy, int len)
602{
603 int nested_len = nla_len(nla) - NLA_ALIGN(len);
604
605 if (nested_len < 0) {
606 pr_info("netem: invalid attributes len %d\n", nested_len);
607 return -EINVAL;
608 }
609
610 if (nested_len >= nla_attr_size(0))
611 return nla_parse(tb, maxtype, nla_data(nla) + NLA_ALIGN(len),
612 nested_len, policy);
613
614 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
615 return 0;
616}
617
618/* Parse netlink message to set options */
619static int netem_change(struct Qdisc *sch, struct nlattr *opt)
620{
621 struct netem_sched_data *q = qdisc_priv(sch);
622 struct nlattr *tb[TCA_NETEM_MAX + 1];
623 struct tc_netem_qopt *qopt;
624 int ret;
625
626 if (opt == NULL)
627 return -EINVAL;
628
629 qopt = nla_data(opt);
630 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
631 if (ret < 0)
632 return ret;
633
634 ret = fifo_set_limit(q->qdisc, qopt->limit);
635 if (ret) {
636 pr_info("netem: can't set fifo limit\n");
637 return ret;
638 }
639
640 q->latency = qopt->latency;
641 q->jitter = qopt->jitter;
642 q->limit = qopt->limit;
643 q->gap = qopt->gap;
644 q->counter = 0;
645 q->loss = qopt->loss;
646 q->duplicate = qopt->duplicate;
647
648 /* for compatibility with earlier versions.
649 * if gap is set, need to assume 100% probability
650 */
651 if (q->gap)
652 q->reorder = ~0;
653
654 if (tb[TCA_NETEM_CORR])
655 get_correlation(sch, tb[TCA_NETEM_CORR]);
656
657 if (tb[TCA_NETEM_DELAY_DIST]) {
658 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
659 if (ret)
660 return ret;
661 }
662
663 if (tb[TCA_NETEM_REORDER])
664 get_reorder(sch, tb[TCA_NETEM_REORDER]);
665
666 if (tb[TCA_NETEM_CORRUPT])
667 get_corrupt(sch, tb[TCA_NETEM_CORRUPT]);
668
669 q->loss_model = CLG_RANDOM;
670 if (tb[TCA_NETEM_LOSS])
671 ret = get_loss_clg(sch, tb[TCA_NETEM_LOSS]);
672
673 return ret;
674}
675
676/*
677 * Special case version of FIFO queue for use by netem.
678 * It queues in order based on timestamps in skb's
679 */
680struct fifo_sched_data {
681 u32 limit;
682 psched_time_t oldest;
683};
684
685static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
686{
687 struct fifo_sched_data *q = qdisc_priv(sch);
688 struct sk_buff_head *list = &sch->q;
689 psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
690 struct sk_buff *skb;
691
692 if (likely(skb_queue_len(list) < q->limit)) {
693 /* Optimize for add at tail */
694 if (likely(skb_queue_empty(list) || tnext >= q->oldest)) {
695 q->oldest = tnext;
696 return qdisc_enqueue_tail(nskb, sch);
697 }
698
699 skb_queue_reverse_walk(list, skb) {
700 const struct netem_skb_cb *cb = netem_skb_cb(skb);
701
702 if (tnext >= cb->time_to_send)
703 break;
704 }
705
706 __skb_queue_after(list, skb, nskb);
707
708 sch->qstats.backlog += qdisc_pkt_len(nskb);
709
710 return NET_XMIT_SUCCESS;
711 }
712
713 return qdisc_reshape_fail(nskb, sch);
714}
715
716static int tfifo_init(struct Qdisc *sch, struct nlattr *opt)
717{
718 struct fifo_sched_data *q = qdisc_priv(sch);
719
720 if (opt) {
721 struct tc_fifo_qopt *ctl = nla_data(opt);
722 if (nla_len(opt) < sizeof(*ctl))
723 return -EINVAL;
724
725 q->limit = ctl->limit;
726 } else
727 q->limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
728
729 q->oldest = PSCHED_PASTPERFECT;
730 return 0;
731}
732
733static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb)
734{
735 struct fifo_sched_data *q = qdisc_priv(sch);
736 struct tc_fifo_qopt opt = { .limit = q->limit };
737
738 NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
739 return skb->len;
740
741nla_put_failure:
742 return -1;
743}
744
745static struct Qdisc_ops tfifo_qdisc_ops __read_mostly = {
746 .id = "tfifo",
747 .priv_size = sizeof(struct fifo_sched_data),
748 .enqueue = tfifo_enqueue,
749 .dequeue = qdisc_dequeue_head,
750 .peek = qdisc_peek_head,
751 .drop = qdisc_queue_drop,
752 .init = tfifo_init,
753 .reset = qdisc_reset_queue,
754 .change = tfifo_init,
755 .dump = tfifo_dump,
756};
757
758static int netem_init(struct Qdisc *sch, struct nlattr *opt)
759{
760 struct netem_sched_data *q = qdisc_priv(sch);
761 int ret;
762
763 if (!opt)
764 return -EINVAL;
765
766 qdisc_watchdog_init(&q->watchdog, sch);
767
768 q->loss_model = CLG_RANDOM;
769 q->qdisc = qdisc_create_dflt(sch->dev_queue, &tfifo_qdisc_ops,
770 TC_H_MAKE(sch->handle, 1));
771 if (!q->qdisc) {
772 pr_notice("netem: qdisc create tfifo qdisc failed\n");
773 return -ENOMEM;
774 }
775
776 ret = netem_change(sch, opt);
777 if (ret) {
778 pr_info("netem: change failed\n");
779 qdisc_destroy(q->qdisc);
780 }
781 return ret;
782}
783
784static void netem_destroy(struct Qdisc *sch)
785{
786 struct netem_sched_data *q = qdisc_priv(sch);
787
788 qdisc_watchdog_cancel(&q->watchdog);
789 qdisc_destroy(q->qdisc);
790 dist_free(q->delay_dist);
791}
792
793static int dump_loss_model(const struct netem_sched_data *q,
794 struct sk_buff *skb)
795{
796 struct nlattr *nest;
797
798 nest = nla_nest_start(skb, TCA_NETEM_LOSS);
799 if (nest == NULL)
800 goto nla_put_failure;
801
802 switch (q->loss_model) {
803 case CLG_RANDOM:
804 /* legacy loss model */
805 nla_nest_cancel(skb, nest);
806 return 0; /* no data */
807
808 case CLG_4_STATES: {
809 struct tc_netem_gimodel gi = {
810 .p13 = q->clg.a1,
811 .p31 = q->clg.a2,
812 .p32 = q->clg.a3,
813 .p14 = q->clg.a4,
814 .p23 = q->clg.a5,
815 };
816
817 NLA_PUT(skb, NETEM_LOSS_GI, sizeof(gi), &gi);
818 break;
819 }
820 case CLG_GILB_ELL: {
821 struct tc_netem_gemodel ge = {
822 .p = q->clg.a1,
823 .r = q->clg.a2,
824 .h = q->clg.a3,
825 .k1 = q->clg.a4,
826 };
827
828 NLA_PUT(skb, NETEM_LOSS_GE, sizeof(ge), &ge);
829 break;
830 }
831 }
832
833 nla_nest_end(skb, nest);
834 return 0;
835
836nla_put_failure:
837 nla_nest_cancel(skb, nest);
838 return -1;
839}
840
841static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
842{
843 const struct netem_sched_data *q = qdisc_priv(sch);
844 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
845 struct tc_netem_qopt qopt;
846 struct tc_netem_corr cor;
847 struct tc_netem_reorder reorder;
848 struct tc_netem_corrupt corrupt;
849
850 qopt.latency = q->latency;
851 qopt.jitter = q->jitter;
852 qopt.limit = q->limit;
853 qopt.loss = q->loss;
854 qopt.gap = q->gap;
855 qopt.duplicate = q->duplicate;
856 NLA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
857
858 cor.delay_corr = q->delay_cor.rho;
859 cor.loss_corr = q->loss_cor.rho;
860 cor.dup_corr = q->dup_cor.rho;
861 NLA_PUT(skb, TCA_NETEM_CORR, sizeof(cor), &cor);
862
863 reorder.probability = q->reorder;
864 reorder.correlation = q->reorder_cor.rho;
865 NLA_PUT(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder);
866
867 corrupt.probability = q->corrupt;
868 corrupt.correlation = q->corrupt_cor.rho;
869 NLA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);
870
871 if (dump_loss_model(q, skb) != 0)
872 goto nla_put_failure;
873
874 return nla_nest_end(skb, nla);
875
876nla_put_failure:
877 nlmsg_trim(skb, nla);
878 return -1;
879}
880
881static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
882 struct sk_buff *skb, struct tcmsg *tcm)
883{
884 struct netem_sched_data *q = qdisc_priv(sch);
885
886 if (cl != 1) /* only one class */
887 return -ENOENT;
888
889 tcm->tcm_handle |= TC_H_MIN(1);
890 tcm->tcm_info = q->qdisc->handle;
891
892 return 0;
893}
894
895static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
896 struct Qdisc **old)
897{
898 struct netem_sched_data *q = qdisc_priv(sch);
899
900 if (new == NULL)
901 new = &noop_qdisc;
902
903 sch_tree_lock(sch);
904 *old = q->qdisc;
905 q->qdisc = new;
906 qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
907 qdisc_reset(*old);
908 sch_tree_unlock(sch);
909
910 return 0;
911}
912
913static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
914{
915 struct netem_sched_data *q = qdisc_priv(sch);
916 return q->qdisc;
917}
918
919static unsigned long netem_get(struct Qdisc *sch, u32 classid)
920{
921 return 1;
922}
923
924static void netem_put(struct Qdisc *sch, unsigned long arg)
925{
926}
927
928static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
929{
930 if (!walker->stop) {
931 if (walker->count >= walker->skip)
932 if (walker->fn(sch, 1, walker) < 0) {
933 walker->stop = 1;
934 return;
935 }
936 walker->count++;
937 }
938}
939
940static const struct Qdisc_class_ops netem_class_ops = {
941 .graft = netem_graft,
942 .leaf = netem_leaf,
943 .get = netem_get,
944 .put = netem_put,
945 .walk = netem_walk,
946 .dump = netem_dump_class,
947};
948
949static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
950 .id = "netem",
951 .cl_ops = &netem_class_ops,
952 .priv_size = sizeof(struct netem_sched_data),
953 .enqueue = netem_enqueue,
954 .dequeue = netem_dequeue,
955 .peek = qdisc_peek_dequeued,
956 .drop = netem_drop,
957 .init = netem_init,
958 .reset = netem_reset,
959 .destroy = netem_destroy,
960 .change = netem_change,
961 .dump = netem_dump,
962 .owner = THIS_MODULE,
963};
964
965
966static int __init netem_module_init(void)
967{
968 pr_info("netem: version " VERSION "\n");
969 return register_qdisc(&netem_qdisc_ops);
970}
971static void __exit netem_module_exit(void)
972{
973 unregister_qdisc(&netem_qdisc_ops);
974}
975module_init(netem_module_init)
976module_exit(netem_module_exit)
977MODULE_LICENSE("GPL");