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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/rtnetlink.h>
21#include <linux/reciprocal_div.h>
22#include <linux/rbtree.h>
23
24#include <net/netlink.h>
25#include <net/pkt_sched.h>
26#include <net/inet_ecn.h>
27
28#define VERSION "1.3"
29
30/* Network Emulation Queuing algorithm.
31 ====================================
32
33 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
34 Network Emulation Tool
35 [2] Luigi Rizzo, DummyNet for FreeBSD
36
37 ----------------------------------------------------------------
38
39 This started out as a simple way to delay outgoing packets to
40 test TCP but has grown to include most of the functionality
41 of a full blown network emulator like NISTnet. It can delay
42 packets and add random jitter (and correlation). The random
43 distribution can be loaded from a table as well to provide
44 normal, Pareto, or experimental curves. Packet loss,
45 duplication, and reordering can also be emulated.
46
47 This qdisc does not do classification that can be handled in
48 layering other disciplines. It does not need to do bandwidth
49 control either since that can be handled by using token
50 bucket or other rate control.
51
52 Correlated Loss Generator models
53
54 Added generation of correlated loss according to the
55 "Gilbert-Elliot" model, a 4-state markov model.
56
57 References:
58 [1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG
59 [2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
60 and intuitive loss model for packet networks and its implementation
61 in the Netem module in the Linux kernel", available in [1]
62
63 Authors: Stefano Salsano <stefano.salsano at uniroma2.it
64 Fabio Ludovici <fabio.ludovici at yahoo.it>
65*/
66
67struct disttable {
68 u32 size;
69 s16 table[];
70};
71
72struct netem_sched_data {
73 /* internal t(ime)fifo qdisc uses t_root and sch->limit */
74 struct rb_root t_root;
75
76 /* a linear queue; reduces rbtree rebalancing when jitter is low */
77 struct sk_buff *t_head;
78 struct sk_buff *t_tail;
79
80 /* optional qdisc for classful handling (NULL at netem init) */
81 struct Qdisc *qdisc;
82
83 struct qdisc_watchdog watchdog;
84
85 s64 latency;
86 s64 jitter;
87
88 u32 loss;
89 u32 ecn;
90 u32 limit;
91 u32 counter;
92 u32 gap;
93 u32 duplicate;
94 u32 reorder;
95 u32 corrupt;
96 u64 rate;
97 s32 packet_overhead;
98 u32 cell_size;
99 struct reciprocal_value cell_size_reciprocal;
100 s32 cell_overhead;
101
102 struct crndstate {
103 u32 last;
104 u32 rho;
105 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
106
107 struct disttable *delay_dist;
108
109 enum {
110 CLG_RANDOM,
111 CLG_4_STATES,
112 CLG_GILB_ELL,
113 } loss_model;
114
115 enum {
116 TX_IN_GAP_PERIOD = 1,
117 TX_IN_BURST_PERIOD,
118 LOST_IN_GAP_PERIOD,
119 LOST_IN_BURST_PERIOD,
120 } _4_state_model;
121
122 enum {
123 GOOD_STATE = 1,
124 BAD_STATE,
125 } GE_state_model;
126
127 /* Correlated Loss Generation models */
128 struct clgstate {
129 /* state of the Markov chain */
130 u8 state;
131
132 /* 4-states and Gilbert-Elliot models */
133 u32 a1; /* p13 for 4-states or p for GE */
134 u32 a2; /* p31 for 4-states or r for GE */
135 u32 a3; /* p32 for 4-states or h for GE */
136 u32 a4; /* p14 for 4-states or 1-k for GE */
137 u32 a5; /* p23 used only in 4-states */
138 } clg;
139
140 struct tc_netem_slot slot_config;
141 struct slotstate {
142 u64 slot_next;
143 s32 packets_left;
144 s32 bytes_left;
145 } slot;
146
147 struct disttable *slot_dist;
148};
149
150/* Time stamp put into socket buffer control block
151 * Only valid when skbs are in our internal t(ime)fifo queue.
152 *
153 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,
154 * and skb->next & skb->prev are scratch space for a qdisc,
155 * we save skb->tstamp value in skb->cb[] before destroying it.
156 */
157struct netem_skb_cb {
158 u64 time_to_send;
159};
160
161static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
162{
163 /* we assume we can use skb next/prev/tstamp as storage for rb_node */
164 qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb));
165 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
166}
167
168/* init_crandom - initialize correlated random number generator
169 * Use entropy source for initial seed.
170 */
171static void init_crandom(struct crndstate *state, unsigned long rho)
172{
173 state->rho = rho;
174 state->last = get_random_u32();
175}
176
177/* get_crandom - correlated random number generator
178 * Next number depends on last value.
179 * rho is scaled to avoid floating point.
180 */
181static u32 get_crandom(struct crndstate *state)
182{
183 u64 value, rho;
184 unsigned long answer;
185
186 if (!state || state->rho == 0) /* no correlation */
187 return get_random_u32();
188
189 value = get_random_u32();
190 rho = (u64)state->rho + 1;
191 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
192 state->last = answer;
193 return answer;
194}
195
196/* loss_4state - 4-state model loss generator
197 * Generates losses according to the 4-state Markov chain adopted in
198 * the GI (General and Intuitive) loss model.
199 */
200static bool loss_4state(struct netem_sched_data *q)
201{
202 struct clgstate *clg = &q->clg;
203 u32 rnd = get_random_u32();
204
205 /*
206 * Makes a comparison between rnd and the transition
207 * probabilities outgoing from the current state, then decides the
208 * next state and if the next packet has to be transmitted or lost.
209 * The four states correspond to:
210 * TX_IN_GAP_PERIOD => successfully transmitted packets within a gap period
211 * LOST_IN_GAP_PERIOD => isolated losses within a gap period
212 * LOST_IN_BURST_PERIOD => lost packets within a burst period
213 * TX_IN_BURST_PERIOD => successfully transmitted packets within a burst period
214 */
215 switch (clg->state) {
216 case TX_IN_GAP_PERIOD:
217 if (rnd < clg->a4) {
218 clg->state = LOST_IN_GAP_PERIOD;
219 return true;
220 } else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {
221 clg->state = LOST_IN_BURST_PERIOD;
222 return true;
223 } else if (clg->a1 + clg->a4 < rnd) {
224 clg->state = TX_IN_GAP_PERIOD;
225 }
226
227 break;
228 case TX_IN_BURST_PERIOD:
229 if (rnd < clg->a5) {
230 clg->state = LOST_IN_BURST_PERIOD;
231 return true;
232 } else {
233 clg->state = TX_IN_BURST_PERIOD;
234 }
235
236 break;
237 case LOST_IN_BURST_PERIOD:
238 if (rnd < clg->a3)
239 clg->state = TX_IN_BURST_PERIOD;
240 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
241 clg->state = TX_IN_GAP_PERIOD;
242 } else if (clg->a2 + clg->a3 < rnd) {
243 clg->state = LOST_IN_BURST_PERIOD;
244 return true;
245 }
246 break;
247 case LOST_IN_GAP_PERIOD:
248 clg->state = TX_IN_GAP_PERIOD;
249 break;
250 }
251
252 return false;
253}
254
255/* loss_gilb_ell - Gilbert-Elliot model loss generator
256 * Generates losses according to the Gilbert-Elliot loss model or
257 * its special cases (Gilbert or Simple Gilbert)
258 *
259 * Makes a comparison between random number and the transition
260 * probabilities outgoing from the current state, then decides the
261 * next state. A second random number is extracted and the comparison
262 * with the loss probability of the current state decides if the next
263 * packet will be transmitted or lost.
264 */
265static bool loss_gilb_ell(struct netem_sched_data *q)
266{
267 struct clgstate *clg = &q->clg;
268
269 switch (clg->state) {
270 case GOOD_STATE:
271 if (get_random_u32() < clg->a1)
272 clg->state = BAD_STATE;
273 if (get_random_u32() < clg->a4)
274 return true;
275 break;
276 case BAD_STATE:
277 if (get_random_u32() < clg->a2)
278 clg->state = GOOD_STATE;
279 if (get_random_u32() > clg->a3)
280 return true;
281 }
282
283 return false;
284}
285
286static bool loss_event(struct netem_sched_data *q)
287{
288 switch (q->loss_model) {
289 case CLG_RANDOM:
290 /* Random packet drop 0 => none, ~0 => all */
291 return q->loss && q->loss >= get_crandom(&q->loss_cor);
292
293 case CLG_4_STATES:
294 /* 4state loss model algorithm (used also for GI model)
295 * Extracts a value from the markov 4 state loss generator,
296 * if it is 1 drops a packet and if needed writes the event in
297 * the kernel logs
298 */
299 return loss_4state(q);
300
301 case CLG_GILB_ELL:
302 /* Gilbert-Elliot loss model algorithm
303 * Extracts a value from the Gilbert-Elliot loss generator,
304 * if it is 1 drops a packet and if needed writes the event in
305 * the kernel logs
306 */
307 return loss_gilb_ell(q);
308 }
309
310 return false; /* not reached */
311}
312
313
314/* tabledist - return a pseudo-randomly distributed value with mean mu and
315 * std deviation sigma. Uses table lookup to approximate the desired
316 * distribution, and a uniformly-distributed pseudo-random source.
317 */
318static s64 tabledist(s64 mu, s32 sigma,
319 struct crndstate *state,
320 const struct disttable *dist)
321{
322 s64 x;
323 long t;
324 u32 rnd;
325
326 if (sigma == 0)
327 return mu;
328
329 rnd = get_crandom(state);
330
331 /* default uniform distribution */
332 if (dist == NULL)
333 return ((rnd % (2 * (u32)sigma)) + mu) - sigma;
334
335 t = dist->table[rnd % dist->size];
336 x = (sigma % NETEM_DIST_SCALE) * t;
337 if (x >= 0)
338 x += NETEM_DIST_SCALE/2;
339 else
340 x -= NETEM_DIST_SCALE/2;
341
342 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
343}
344
345static u64 packet_time_ns(u64 len, const struct netem_sched_data *q)
346{
347 len += q->packet_overhead;
348
349 if (q->cell_size) {
350 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
351
352 if (len > cells * q->cell_size) /* extra cell needed for remainder */
353 cells++;
354 len = cells * (q->cell_size + q->cell_overhead);
355 }
356
357 return div64_u64(len * NSEC_PER_SEC, q->rate);
358}
359
360static void tfifo_reset(struct Qdisc *sch)
361{
362 struct netem_sched_data *q = qdisc_priv(sch);
363 struct rb_node *p = rb_first(&q->t_root);
364
365 while (p) {
366 struct sk_buff *skb = rb_to_skb(p);
367
368 p = rb_next(p);
369 rb_erase(&skb->rbnode, &q->t_root);
370 rtnl_kfree_skbs(skb, skb);
371 }
372
373 rtnl_kfree_skbs(q->t_head, q->t_tail);
374 q->t_head = NULL;
375 q->t_tail = NULL;
376}
377
378static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
379{
380 struct netem_sched_data *q = qdisc_priv(sch);
381 u64 tnext = netem_skb_cb(nskb)->time_to_send;
382
383 if (!q->t_tail || tnext >= netem_skb_cb(q->t_tail)->time_to_send) {
384 if (q->t_tail)
385 q->t_tail->next = nskb;
386 else
387 q->t_head = nskb;
388 q->t_tail = nskb;
389 } else {
390 struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
391
392 while (*p) {
393 struct sk_buff *skb;
394
395 parent = *p;
396 skb = rb_to_skb(parent);
397 if (tnext >= netem_skb_cb(skb)->time_to_send)
398 p = &parent->rb_right;
399 else
400 p = &parent->rb_left;
401 }
402 rb_link_node(&nskb->rbnode, parent, p);
403 rb_insert_color(&nskb->rbnode, &q->t_root);
404 }
405 sch->q.qlen++;
406}
407
408/* netem can't properly corrupt a megapacket (like we get from GSO), so instead
409 * when we statistically choose to corrupt one, we instead segment it, returning
410 * the first packet to be corrupted, and re-enqueue the remaining frames
411 */
412static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
413 struct sk_buff **to_free)
414{
415 struct sk_buff *segs;
416 netdev_features_t features = netif_skb_features(skb);
417
418 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
419
420 if (IS_ERR_OR_NULL(segs)) {
421 qdisc_drop(skb, sch, to_free);
422 return NULL;
423 }
424 consume_skb(skb);
425 return segs;
426}
427
428/*
429 * Insert one skb into qdisc.
430 * Note: parent depends on return value to account for queue length.
431 * NET_XMIT_DROP: queue length didn't change.
432 * NET_XMIT_SUCCESS: one skb was queued.
433 */
434static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
435 struct sk_buff **to_free)
436{
437 struct netem_sched_data *q = qdisc_priv(sch);
438 /* We don't fill cb now as skb_unshare() may invalidate it */
439 struct netem_skb_cb *cb;
440 struct sk_buff *skb2;
441 struct sk_buff *segs = NULL;
442 unsigned int prev_len = qdisc_pkt_len(skb);
443 int count = 1;
444 int rc = NET_XMIT_SUCCESS;
445 int rc_drop = NET_XMIT_DROP;
446
447 /* Do not fool qdisc_drop_all() */
448 skb->prev = NULL;
449
450 /* Random duplication */
451 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
452 ++count;
453
454 /* Drop packet? */
455 if (loss_event(q)) {
456 if (q->ecn && INET_ECN_set_ce(skb))
457 qdisc_qstats_drop(sch); /* mark packet */
458 else
459 --count;
460 }
461 if (count == 0) {
462 qdisc_qstats_drop(sch);
463 __qdisc_drop(skb, to_free);
464 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
465 }
466
467 /* If a delay is expected, orphan the skb. (orphaning usually takes
468 * place at TX completion time, so _before_ the link transit delay)
469 */
470 if (q->latency || q->jitter || q->rate)
471 skb_orphan_partial(skb);
472
473 /*
474 * If we need to duplicate packet, then re-insert at top of the
475 * qdisc tree, since parent queuer expects that only one
476 * skb will be queued.
477 */
478 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
479 struct Qdisc *rootq = qdisc_root_bh(sch);
480 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
481
482 q->duplicate = 0;
483 rootq->enqueue(skb2, rootq, to_free);
484 q->duplicate = dupsave;
485 rc_drop = NET_XMIT_SUCCESS;
486 }
487
488 /*
489 * Randomized packet corruption.
490 * Make copy if needed since we are modifying
491 * If packet is going to be hardware checksummed, then
492 * do it now in software before we mangle it.
493 */
494 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
495 if (skb_is_gso(skb)) {
496 skb = netem_segment(skb, sch, to_free);
497 if (!skb)
498 return rc_drop;
499 segs = skb->next;
500 skb_mark_not_on_list(skb);
501 qdisc_skb_cb(skb)->pkt_len = skb->len;
502 }
503
504 skb = skb_unshare(skb, GFP_ATOMIC);
505 if (unlikely(!skb)) {
506 qdisc_qstats_drop(sch);
507 goto finish_segs;
508 }
509 if (skb->ip_summed == CHECKSUM_PARTIAL &&
510 skb_checksum_help(skb)) {
511 qdisc_drop(skb, sch, to_free);
512 skb = NULL;
513 goto finish_segs;
514 }
515
516 skb->data[get_random_u32_below(skb_headlen(skb))] ^=
517 1<<get_random_u32_below(8);
518 }
519
520 if (unlikely(sch->q.qlen >= sch->limit)) {
521 /* re-link segs, so that qdisc_drop_all() frees them all */
522 skb->next = segs;
523 qdisc_drop_all(skb, sch, to_free);
524 return rc_drop;
525 }
526
527 qdisc_qstats_backlog_inc(sch, skb);
528
529 cb = netem_skb_cb(skb);
530 if (q->gap == 0 || /* not doing reordering */
531 q->counter < q->gap - 1 || /* inside last reordering gap */
532 q->reorder < get_crandom(&q->reorder_cor)) {
533 u64 now;
534 s64 delay;
535
536 delay = tabledist(q->latency, q->jitter,
537 &q->delay_cor, q->delay_dist);
538
539 now = ktime_get_ns();
540
541 if (q->rate) {
542 struct netem_skb_cb *last = NULL;
543
544 if (sch->q.tail)
545 last = netem_skb_cb(sch->q.tail);
546 if (q->t_root.rb_node) {
547 struct sk_buff *t_skb;
548 struct netem_skb_cb *t_last;
549
550 t_skb = skb_rb_last(&q->t_root);
551 t_last = netem_skb_cb(t_skb);
552 if (!last ||
553 t_last->time_to_send > last->time_to_send)
554 last = t_last;
555 }
556 if (q->t_tail) {
557 struct netem_skb_cb *t_last =
558 netem_skb_cb(q->t_tail);
559
560 if (!last ||
561 t_last->time_to_send > last->time_to_send)
562 last = t_last;
563 }
564
565 if (last) {
566 /*
567 * Last packet in queue is reference point (now),
568 * calculate this time bonus and subtract
569 * from delay.
570 */
571 delay -= last->time_to_send - now;
572 delay = max_t(s64, 0, delay);
573 now = last->time_to_send;
574 }
575
576 delay += packet_time_ns(qdisc_pkt_len(skb), q);
577 }
578
579 cb->time_to_send = now + delay;
580 ++q->counter;
581 tfifo_enqueue(skb, sch);
582 } else {
583 /*
584 * Do re-ordering by putting one out of N packets at the front
585 * of the queue.
586 */
587 cb->time_to_send = ktime_get_ns();
588 q->counter = 0;
589
590 __qdisc_enqueue_head(skb, &sch->q);
591 sch->qstats.requeues++;
592 }
593
594finish_segs:
595 if (segs) {
596 unsigned int len, last_len;
597 int nb;
598
599 len = skb ? skb->len : 0;
600 nb = skb ? 1 : 0;
601
602 while (segs) {
603 skb2 = segs->next;
604 skb_mark_not_on_list(segs);
605 qdisc_skb_cb(segs)->pkt_len = segs->len;
606 last_len = segs->len;
607 rc = qdisc_enqueue(segs, sch, to_free);
608 if (rc != NET_XMIT_SUCCESS) {
609 if (net_xmit_drop_count(rc))
610 qdisc_qstats_drop(sch);
611 } else {
612 nb++;
613 len += last_len;
614 }
615 segs = skb2;
616 }
617 /* Parent qdiscs accounted for 1 skb of size @prev_len */
618 qdisc_tree_reduce_backlog(sch, -(nb - 1), -(len - prev_len));
619 } else if (!skb) {
620 return NET_XMIT_DROP;
621 }
622 return NET_XMIT_SUCCESS;
623}
624
625/* Delay the next round with a new future slot with a
626 * correct number of bytes and packets.
627 */
628
629static void get_slot_next(struct netem_sched_data *q, u64 now)
630{
631 s64 next_delay;
632
633 if (!q->slot_dist)
634 next_delay = q->slot_config.min_delay +
635 (get_random_u32() *
636 (q->slot_config.max_delay -
637 q->slot_config.min_delay) >> 32);
638 else
639 next_delay = tabledist(q->slot_config.dist_delay,
640 (s32)(q->slot_config.dist_jitter),
641 NULL, q->slot_dist);
642
643 q->slot.slot_next = now + next_delay;
644 q->slot.packets_left = q->slot_config.max_packets;
645 q->slot.bytes_left = q->slot_config.max_bytes;
646}
647
648static struct sk_buff *netem_peek(struct netem_sched_data *q)
649{
650 struct sk_buff *skb = skb_rb_first(&q->t_root);
651 u64 t1, t2;
652
653 if (!skb)
654 return q->t_head;
655 if (!q->t_head)
656 return skb;
657
658 t1 = netem_skb_cb(skb)->time_to_send;
659 t2 = netem_skb_cb(q->t_head)->time_to_send;
660 if (t1 < t2)
661 return skb;
662 return q->t_head;
663}
664
665static void netem_erase_head(struct netem_sched_data *q, struct sk_buff *skb)
666{
667 if (skb == q->t_head) {
668 q->t_head = skb->next;
669 if (!q->t_head)
670 q->t_tail = NULL;
671 } else {
672 rb_erase(&skb->rbnode, &q->t_root);
673 }
674}
675
676static struct sk_buff *netem_dequeue(struct Qdisc *sch)
677{
678 struct netem_sched_data *q = qdisc_priv(sch);
679 struct sk_buff *skb;
680
681tfifo_dequeue:
682 skb = __qdisc_dequeue_head(&sch->q);
683 if (skb) {
684 qdisc_qstats_backlog_dec(sch, skb);
685deliver:
686 qdisc_bstats_update(sch, skb);
687 return skb;
688 }
689 skb = netem_peek(q);
690 if (skb) {
691 u64 time_to_send;
692 u64 now = ktime_get_ns();
693
694 /* if more time remaining? */
695 time_to_send = netem_skb_cb(skb)->time_to_send;
696 if (q->slot.slot_next && q->slot.slot_next < time_to_send)
697 get_slot_next(q, now);
698
699 if (time_to_send <= now && q->slot.slot_next <= now) {
700 netem_erase_head(q, skb);
701 sch->q.qlen--;
702 qdisc_qstats_backlog_dec(sch, skb);
703 skb->next = NULL;
704 skb->prev = NULL;
705 /* skb->dev shares skb->rbnode area,
706 * we need to restore its value.
707 */
708 skb->dev = qdisc_dev(sch);
709
710 if (q->slot.slot_next) {
711 q->slot.packets_left--;
712 q->slot.bytes_left -= qdisc_pkt_len(skb);
713 if (q->slot.packets_left <= 0 ||
714 q->slot.bytes_left <= 0)
715 get_slot_next(q, now);
716 }
717
718 if (q->qdisc) {
719 unsigned int pkt_len = qdisc_pkt_len(skb);
720 struct sk_buff *to_free = NULL;
721 int err;
722
723 err = qdisc_enqueue(skb, q->qdisc, &to_free);
724 kfree_skb_list(to_free);
725 if (err != NET_XMIT_SUCCESS &&
726 net_xmit_drop_count(err)) {
727 qdisc_qstats_drop(sch);
728 qdisc_tree_reduce_backlog(sch, 1,
729 pkt_len);
730 }
731 goto tfifo_dequeue;
732 }
733 goto deliver;
734 }
735
736 if (q->qdisc) {
737 skb = q->qdisc->ops->dequeue(q->qdisc);
738 if (skb)
739 goto deliver;
740 }
741
742 qdisc_watchdog_schedule_ns(&q->watchdog,
743 max(time_to_send,
744 q->slot.slot_next));
745 }
746
747 if (q->qdisc) {
748 skb = q->qdisc->ops->dequeue(q->qdisc);
749 if (skb)
750 goto deliver;
751 }
752 return NULL;
753}
754
755static void netem_reset(struct Qdisc *sch)
756{
757 struct netem_sched_data *q = qdisc_priv(sch);
758
759 qdisc_reset_queue(sch);
760 tfifo_reset(sch);
761 if (q->qdisc)
762 qdisc_reset(q->qdisc);
763 qdisc_watchdog_cancel(&q->watchdog);
764}
765
766static void dist_free(struct disttable *d)
767{
768 kvfree(d);
769}
770
771/*
772 * Distribution data is a variable size payload containing
773 * signed 16 bit values.
774 */
775
776static int get_dist_table(struct Qdisc *sch, struct disttable **tbl,
777 const struct nlattr *attr)
778{
779 size_t n = nla_len(attr)/sizeof(__s16);
780 const __s16 *data = nla_data(attr);
781 spinlock_t *root_lock;
782 struct disttable *d;
783 int i;
784
785 if (!n || n > NETEM_DIST_MAX)
786 return -EINVAL;
787
788 d = kvmalloc(struct_size(d, table, n), GFP_KERNEL);
789 if (!d)
790 return -ENOMEM;
791
792 d->size = n;
793 for (i = 0; i < n; i++)
794 d->table[i] = data[i];
795
796 root_lock = qdisc_root_sleeping_lock(sch);
797
798 spin_lock_bh(root_lock);
799 swap(*tbl, d);
800 spin_unlock_bh(root_lock);
801
802 dist_free(d);
803 return 0;
804}
805
806static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
807{
808 const struct tc_netem_slot *c = nla_data(attr);
809
810 q->slot_config = *c;
811 if (q->slot_config.max_packets == 0)
812 q->slot_config.max_packets = INT_MAX;
813 if (q->slot_config.max_bytes == 0)
814 q->slot_config.max_bytes = INT_MAX;
815
816 /* capping dist_jitter to the range acceptable by tabledist() */
817 q->slot_config.dist_jitter = min_t(__s64, INT_MAX, abs(q->slot_config.dist_jitter));
818
819 q->slot.packets_left = q->slot_config.max_packets;
820 q->slot.bytes_left = q->slot_config.max_bytes;
821 if (q->slot_config.min_delay | q->slot_config.max_delay |
822 q->slot_config.dist_jitter)
823 q->slot.slot_next = ktime_get_ns();
824 else
825 q->slot.slot_next = 0;
826}
827
828static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
829{
830 const struct tc_netem_corr *c = nla_data(attr);
831
832 init_crandom(&q->delay_cor, c->delay_corr);
833 init_crandom(&q->loss_cor, c->loss_corr);
834 init_crandom(&q->dup_cor, c->dup_corr);
835}
836
837static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
838{
839 const struct tc_netem_reorder *r = nla_data(attr);
840
841 q->reorder = r->probability;
842 init_crandom(&q->reorder_cor, r->correlation);
843}
844
845static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
846{
847 const struct tc_netem_corrupt *r = nla_data(attr);
848
849 q->corrupt = r->probability;
850 init_crandom(&q->corrupt_cor, r->correlation);
851}
852
853static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
854{
855 const struct tc_netem_rate *r = nla_data(attr);
856
857 q->rate = r->rate;
858 q->packet_overhead = r->packet_overhead;
859 q->cell_size = r->cell_size;
860 q->cell_overhead = r->cell_overhead;
861 if (q->cell_size)
862 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
863 else
864 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
865}
866
867static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
868{
869 const struct nlattr *la;
870 int rem;
871
872 nla_for_each_nested(la, attr, rem) {
873 u16 type = nla_type(la);
874
875 switch (type) {
876 case NETEM_LOSS_GI: {
877 const struct tc_netem_gimodel *gi = nla_data(la);
878
879 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
880 pr_info("netem: incorrect gi model size\n");
881 return -EINVAL;
882 }
883
884 q->loss_model = CLG_4_STATES;
885
886 q->clg.state = TX_IN_GAP_PERIOD;
887 q->clg.a1 = gi->p13;
888 q->clg.a2 = gi->p31;
889 q->clg.a3 = gi->p32;
890 q->clg.a4 = gi->p14;
891 q->clg.a5 = gi->p23;
892 break;
893 }
894
895 case NETEM_LOSS_GE: {
896 const struct tc_netem_gemodel *ge = nla_data(la);
897
898 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
899 pr_info("netem: incorrect ge model size\n");
900 return -EINVAL;
901 }
902
903 q->loss_model = CLG_GILB_ELL;
904 q->clg.state = GOOD_STATE;
905 q->clg.a1 = ge->p;
906 q->clg.a2 = ge->r;
907 q->clg.a3 = ge->h;
908 q->clg.a4 = ge->k1;
909 break;
910 }
911
912 default:
913 pr_info("netem: unknown loss type %u\n", type);
914 return -EINVAL;
915 }
916 }
917
918 return 0;
919}
920
921static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
922 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
923 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
924 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
925 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
926 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
927 [TCA_NETEM_ECN] = { .type = NLA_U32 },
928 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
929 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
930 [TCA_NETEM_JITTER64] = { .type = NLA_S64 },
931 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
932};
933
934static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
935 const struct nla_policy *policy, int len)
936{
937 int nested_len = nla_len(nla) - NLA_ALIGN(len);
938
939 if (nested_len < 0) {
940 pr_info("netem: invalid attributes len %d\n", nested_len);
941 return -EINVAL;
942 }
943
944 if (nested_len >= nla_attr_size(0))
945 return nla_parse_deprecated(tb, maxtype,
946 nla_data(nla) + NLA_ALIGN(len),
947 nested_len, policy, NULL);
948
949 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
950 return 0;
951}
952
953/* Parse netlink message to set options */
954static int netem_change(struct Qdisc *sch, struct nlattr *opt,
955 struct netlink_ext_ack *extack)
956{
957 struct netem_sched_data *q = qdisc_priv(sch);
958 struct nlattr *tb[TCA_NETEM_MAX + 1];
959 struct tc_netem_qopt *qopt;
960 struct clgstate old_clg;
961 int old_loss_model = CLG_RANDOM;
962 int ret;
963
964 qopt = nla_data(opt);
965 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
966 if (ret < 0)
967 return ret;
968
969 /* backup q->clg and q->loss_model */
970 old_clg = q->clg;
971 old_loss_model = q->loss_model;
972
973 if (tb[TCA_NETEM_LOSS]) {
974 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
975 if (ret) {
976 q->loss_model = old_loss_model;
977 return ret;
978 }
979 } else {
980 q->loss_model = CLG_RANDOM;
981 }
982
983 if (tb[TCA_NETEM_DELAY_DIST]) {
984 ret = get_dist_table(sch, &q->delay_dist,
985 tb[TCA_NETEM_DELAY_DIST]);
986 if (ret)
987 goto get_table_failure;
988 }
989
990 if (tb[TCA_NETEM_SLOT_DIST]) {
991 ret = get_dist_table(sch, &q->slot_dist,
992 tb[TCA_NETEM_SLOT_DIST]);
993 if (ret)
994 goto get_table_failure;
995 }
996
997 sch->limit = qopt->limit;
998
999 q->latency = PSCHED_TICKS2NS(qopt->latency);
1000 q->jitter = PSCHED_TICKS2NS(qopt->jitter);
1001 q->limit = qopt->limit;
1002 q->gap = qopt->gap;
1003 q->counter = 0;
1004 q->loss = qopt->loss;
1005 q->duplicate = qopt->duplicate;
1006
1007 /* for compatibility with earlier versions.
1008 * if gap is set, need to assume 100% probability
1009 */
1010 if (q->gap)
1011 q->reorder = ~0;
1012
1013 if (tb[TCA_NETEM_CORR])
1014 get_correlation(q, tb[TCA_NETEM_CORR]);
1015
1016 if (tb[TCA_NETEM_REORDER])
1017 get_reorder(q, tb[TCA_NETEM_REORDER]);
1018
1019 if (tb[TCA_NETEM_CORRUPT])
1020 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
1021
1022 if (tb[TCA_NETEM_RATE])
1023 get_rate(q, tb[TCA_NETEM_RATE]);
1024
1025 if (tb[TCA_NETEM_RATE64])
1026 q->rate = max_t(u64, q->rate,
1027 nla_get_u64(tb[TCA_NETEM_RATE64]));
1028
1029 if (tb[TCA_NETEM_LATENCY64])
1030 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
1031
1032 if (tb[TCA_NETEM_JITTER64])
1033 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
1034
1035 if (tb[TCA_NETEM_ECN])
1036 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
1037
1038 if (tb[TCA_NETEM_SLOT])
1039 get_slot(q, tb[TCA_NETEM_SLOT]);
1040
1041 /* capping jitter to the range acceptable by tabledist() */
1042 q->jitter = min_t(s64, abs(q->jitter), INT_MAX);
1043
1044 return ret;
1045
1046get_table_failure:
1047 /* recover clg and loss_model, in case of
1048 * q->clg and q->loss_model were modified
1049 * in get_loss_clg()
1050 */
1051 q->clg = old_clg;
1052 q->loss_model = old_loss_model;
1053 return ret;
1054}
1055
1056static int netem_init(struct Qdisc *sch, struct nlattr *opt,
1057 struct netlink_ext_ack *extack)
1058{
1059 struct netem_sched_data *q = qdisc_priv(sch);
1060 int ret;
1061
1062 qdisc_watchdog_init(&q->watchdog, sch);
1063
1064 if (!opt)
1065 return -EINVAL;
1066
1067 q->loss_model = CLG_RANDOM;
1068 ret = netem_change(sch, opt, extack);
1069 if (ret)
1070 pr_info("netem: change failed\n");
1071 return ret;
1072}
1073
1074static void netem_destroy(struct Qdisc *sch)
1075{
1076 struct netem_sched_data *q = qdisc_priv(sch);
1077
1078 qdisc_watchdog_cancel(&q->watchdog);
1079 if (q->qdisc)
1080 qdisc_put(q->qdisc);
1081 dist_free(q->delay_dist);
1082 dist_free(q->slot_dist);
1083}
1084
1085static int dump_loss_model(const struct netem_sched_data *q,
1086 struct sk_buff *skb)
1087{
1088 struct nlattr *nest;
1089
1090 nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS);
1091 if (nest == NULL)
1092 goto nla_put_failure;
1093
1094 switch (q->loss_model) {
1095 case CLG_RANDOM:
1096 /* legacy loss model */
1097 nla_nest_cancel(skb, nest);
1098 return 0; /* no data */
1099
1100 case CLG_4_STATES: {
1101 struct tc_netem_gimodel gi = {
1102 .p13 = q->clg.a1,
1103 .p31 = q->clg.a2,
1104 .p32 = q->clg.a3,
1105 .p14 = q->clg.a4,
1106 .p23 = q->clg.a5,
1107 };
1108
1109 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
1110 goto nla_put_failure;
1111 break;
1112 }
1113 case CLG_GILB_ELL: {
1114 struct tc_netem_gemodel ge = {
1115 .p = q->clg.a1,
1116 .r = q->clg.a2,
1117 .h = q->clg.a3,
1118 .k1 = q->clg.a4,
1119 };
1120
1121 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1122 goto nla_put_failure;
1123 break;
1124 }
1125 }
1126
1127 nla_nest_end(skb, nest);
1128 return 0;
1129
1130nla_put_failure:
1131 nla_nest_cancel(skb, nest);
1132 return -1;
1133}
1134
1135static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1136{
1137 const struct netem_sched_data *q = qdisc_priv(sch);
1138 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1139 struct tc_netem_qopt qopt;
1140 struct tc_netem_corr cor;
1141 struct tc_netem_reorder reorder;
1142 struct tc_netem_corrupt corrupt;
1143 struct tc_netem_rate rate;
1144 struct tc_netem_slot slot;
1145
1146 qopt.latency = min_t(psched_time_t, PSCHED_NS2TICKS(q->latency),
1147 UINT_MAX);
1148 qopt.jitter = min_t(psched_time_t, PSCHED_NS2TICKS(q->jitter),
1149 UINT_MAX);
1150 qopt.limit = q->limit;
1151 qopt.loss = q->loss;
1152 qopt.gap = q->gap;
1153 qopt.duplicate = q->duplicate;
1154 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1155 goto nla_put_failure;
1156
1157 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
1158 goto nla_put_failure;
1159
1160 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
1161 goto nla_put_failure;
1162
1163 cor.delay_corr = q->delay_cor.rho;
1164 cor.loss_corr = q->loss_cor.rho;
1165 cor.dup_corr = q->dup_cor.rho;
1166 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1167 goto nla_put_failure;
1168
1169 reorder.probability = q->reorder;
1170 reorder.correlation = q->reorder_cor.rho;
1171 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1172 goto nla_put_failure;
1173
1174 corrupt.probability = q->corrupt;
1175 corrupt.correlation = q->corrupt_cor.rho;
1176 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1177 goto nla_put_failure;
1178
1179 if (q->rate >= (1ULL << 32)) {
1180 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1181 TCA_NETEM_PAD))
1182 goto nla_put_failure;
1183 rate.rate = ~0U;
1184 } else {
1185 rate.rate = q->rate;
1186 }
1187 rate.packet_overhead = q->packet_overhead;
1188 rate.cell_size = q->cell_size;
1189 rate.cell_overhead = q->cell_overhead;
1190 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1191 goto nla_put_failure;
1192
1193 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1194 goto nla_put_failure;
1195
1196 if (dump_loss_model(q, skb) != 0)
1197 goto nla_put_failure;
1198
1199 if (q->slot_config.min_delay | q->slot_config.max_delay |
1200 q->slot_config.dist_jitter) {
1201 slot = q->slot_config;
1202 if (slot.max_packets == INT_MAX)
1203 slot.max_packets = 0;
1204 if (slot.max_bytes == INT_MAX)
1205 slot.max_bytes = 0;
1206 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
1207 goto nla_put_failure;
1208 }
1209
1210 return nla_nest_end(skb, nla);
1211
1212nla_put_failure:
1213 nlmsg_trim(skb, nla);
1214 return -1;
1215}
1216
1217static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1218 struct sk_buff *skb, struct tcmsg *tcm)
1219{
1220 struct netem_sched_data *q = qdisc_priv(sch);
1221
1222 if (cl != 1 || !q->qdisc) /* only one class */
1223 return -ENOENT;
1224
1225 tcm->tcm_handle |= TC_H_MIN(1);
1226 tcm->tcm_info = q->qdisc->handle;
1227
1228 return 0;
1229}
1230
1231static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1232 struct Qdisc **old, struct netlink_ext_ack *extack)
1233{
1234 struct netem_sched_data *q = qdisc_priv(sch);
1235
1236 *old = qdisc_replace(sch, new, &q->qdisc);
1237 return 0;
1238}
1239
1240static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1241{
1242 struct netem_sched_data *q = qdisc_priv(sch);
1243 return q->qdisc;
1244}
1245
1246static unsigned long netem_find(struct Qdisc *sch, u32 classid)
1247{
1248 return 1;
1249}
1250
1251static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1252{
1253 if (!walker->stop) {
1254 if (!tc_qdisc_stats_dump(sch, 1, walker))
1255 return;
1256 }
1257}
1258
1259static const struct Qdisc_class_ops netem_class_ops = {
1260 .graft = netem_graft,
1261 .leaf = netem_leaf,
1262 .find = netem_find,
1263 .walk = netem_walk,
1264 .dump = netem_dump_class,
1265};
1266
1267static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1268 .id = "netem",
1269 .cl_ops = &netem_class_ops,
1270 .priv_size = sizeof(struct netem_sched_data),
1271 .enqueue = netem_enqueue,
1272 .dequeue = netem_dequeue,
1273 .peek = qdisc_peek_dequeued,
1274 .init = netem_init,
1275 .reset = netem_reset,
1276 .destroy = netem_destroy,
1277 .change = netem_change,
1278 .dump = netem_dump,
1279 .owner = THIS_MODULE,
1280};
1281
1282
1283static int __init netem_module_init(void)
1284{
1285 pr_info("netem: version " VERSION "\n");
1286 return register_qdisc(&netem_qdisc_ops);
1287}
1288static void __exit netem_module_exit(void)
1289{
1290 unregister_qdisc(&netem_qdisc_ops);
1291}
1292module_init(netem_module_init)
1293module_exit(netem_module_exit)
1294MODULE_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 psched_tdiff_t latency;
81 psched_tdiff_t 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};
139
140/* Time stamp put into socket buffer control block
141 * Only valid when skbs are in our internal t(ime)fifo queue.
142 *
143 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,
144 * and skb->next & skb->prev are scratch space for a qdisc,
145 * we save skb->tstamp value in skb->cb[] before destroying it.
146 */
147struct netem_skb_cb {
148 psched_time_t time_to_send;
149 ktime_t tstamp_save;
150};
151
152
153static struct sk_buff *netem_rb_to_skb(struct rb_node *rb)
154{
155 return container_of(rb, struct sk_buff, rbnode);
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 psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
316 struct crndstate *state,
317 const struct disttable *dist)
318{
319 psched_tdiff_t 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)) - sigma + mu;
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 psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sched_data *q)
343{
344 u64 ticks;
345
346 len += q->packet_overhead;
347
348 if (q->cell_size) {
349 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
350
351 if (len > cells * q->cell_size) /* extra cell needed for remainder */
352 cells++;
353 len = cells * (q->cell_size + q->cell_overhead);
354 }
355
356 ticks = (u64)len * NSEC_PER_SEC;
357
358 do_div(ticks, q->rate);
359 return PSCHED_NS2TICKS(ticks);
360}
361
362static void tfifo_reset(struct Qdisc *sch)
363{
364 struct netem_sched_data *q = qdisc_priv(sch);
365 struct rb_node *p;
366
367 while ((p = rb_first(&q->t_root))) {
368 struct sk_buff *skb = netem_rb_to_skb(p);
369
370 rb_erase(p, &q->t_root);
371 skb->next = NULL;
372 skb->prev = NULL;
373 kfree_skb(skb);
374 }
375}
376
377static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
378{
379 struct netem_sched_data *q = qdisc_priv(sch);
380 psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
381 struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
382
383 while (*p) {
384 struct sk_buff *skb;
385
386 parent = *p;
387 skb = netem_rb_to_skb(parent);
388 if (tnext >= netem_skb_cb(skb)->time_to_send)
389 p = &parent->rb_right;
390 else
391 p = &parent->rb_left;
392 }
393 rb_link_node(&nskb->rbnode, parent, p);
394 rb_insert_color(&nskb->rbnode, &q->t_root);
395 sch->q.qlen++;
396}
397
398/* netem can't properly corrupt a megapacket (like we get from GSO), so instead
399 * when we statistically choose to corrupt one, we instead segment it, returning
400 * the first packet to be corrupted, and re-enqueue the remaining frames
401 */
402static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch)
403{
404 struct sk_buff *segs;
405 netdev_features_t features = netif_skb_features(skb);
406
407 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
408
409 if (IS_ERR_OR_NULL(segs)) {
410 qdisc_reshape_fail(skb, sch);
411 return NULL;
412 }
413 consume_skb(skb);
414 return segs;
415}
416
417/*
418 * Insert one skb into qdisc.
419 * Note: parent depends on return value to account for queue length.
420 * NET_XMIT_DROP: queue length didn't change.
421 * NET_XMIT_SUCCESS: one skb was queued.
422 */
423static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
424{
425 struct netem_sched_data *q = qdisc_priv(sch);
426 /* We don't fill cb now as skb_unshare() may invalidate it */
427 struct netem_skb_cb *cb;
428 struct sk_buff *skb2;
429 struct sk_buff *segs = NULL;
430 unsigned int len = 0, last_len, prev_len = qdisc_pkt_len(skb);
431 int nb = 0;
432 int count = 1;
433 int rc = NET_XMIT_SUCCESS;
434
435 /* Random duplication */
436 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
437 ++count;
438
439 /* Drop packet? */
440 if (loss_event(q)) {
441 if (q->ecn && INET_ECN_set_ce(skb))
442 qdisc_qstats_drop(sch); /* mark packet */
443 else
444 --count;
445 }
446 if (count == 0) {
447 qdisc_qstats_drop(sch);
448 kfree_skb(skb);
449 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
450 }
451
452 /* If a delay is expected, orphan the skb. (orphaning usually takes
453 * place at TX completion time, so _before_ the link transit delay)
454 */
455 if (q->latency || q->jitter)
456 skb_orphan_partial(skb);
457
458 /*
459 * If we need to duplicate packet, then re-insert at top of the
460 * qdisc tree, since parent queuer expects that only one
461 * skb will be queued.
462 */
463 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
464 struct Qdisc *rootq = qdisc_root(sch);
465 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
466
467 q->duplicate = 0;
468 rootq->enqueue(skb2, rootq);
469 q->duplicate = dupsave;
470 }
471
472 /*
473 * Randomized packet corruption.
474 * Make copy if needed since we are modifying
475 * If packet is going to be hardware checksummed, then
476 * do it now in software before we mangle it.
477 */
478 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
479 if (skb_is_gso(skb)) {
480 segs = netem_segment(skb, sch);
481 if (!segs)
482 return NET_XMIT_DROP;
483 } else {
484 segs = skb;
485 }
486
487 skb = segs;
488 segs = segs->next;
489
490 if (!(skb = skb_unshare(skb, GFP_ATOMIC)) ||
491 (skb->ip_summed == CHECKSUM_PARTIAL &&
492 skb_checksum_help(skb))) {
493 rc = qdisc_drop(skb, sch);
494 goto finish_segs;
495 }
496
497 skb->data[prandom_u32() % skb_headlen(skb)] ^=
498 1<<(prandom_u32() % 8);
499 }
500
501 if (unlikely(skb_queue_len(&sch->q) >= sch->limit))
502 return qdisc_reshape_fail(skb, sch);
503
504 qdisc_qstats_backlog_inc(sch, skb);
505
506 cb = netem_skb_cb(skb);
507 if (q->gap == 0 || /* not doing reordering */
508 q->counter < q->gap - 1 || /* inside last reordering gap */
509 q->reorder < get_crandom(&q->reorder_cor)) {
510 psched_time_t now;
511 psched_tdiff_t delay;
512
513 delay = tabledist(q->latency, q->jitter,
514 &q->delay_cor, q->delay_dist);
515
516 now = psched_get_time();
517
518 if (q->rate) {
519 struct sk_buff *last;
520
521 if (!skb_queue_empty(&sch->q))
522 last = skb_peek_tail(&sch->q);
523 else
524 last = netem_rb_to_skb(rb_last(&q->t_root));
525 if (last) {
526 /*
527 * Last packet in queue is reference point (now),
528 * calculate this time bonus and subtract
529 * from delay.
530 */
531 delay -= netem_skb_cb(last)->time_to_send - now;
532 delay = max_t(psched_tdiff_t, 0, delay);
533 now = netem_skb_cb(last)->time_to_send;
534 }
535
536 delay += packet_len_2_sched_time(qdisc_pkt_len(skb), q);
537 }
538
539 cb->time_to_send = now + delay;
540 cb->tstamp_save = skb->tstamp;
541 ++q->counter;
542 tfifo_enqueue(skb, sch);
543 } else {
544 /*
545 * Do re-ordering by putting one out of N packets at the front
546 * of the queue.
547 */
548 cb->time_to_send = psched_get_time();
549 q->counter = 0;
550
551 __skb_queue_head(&sch->q, skb);
552 sch->qstats.requeues++;
553 }
554
555finish_segs:
556 if (segs) {
557 while (segs) {
558 skb2 = segs->next;
559 segs->next = NULL;
560 qdisc_skb_cb(segs)->pkt_len = segs->len;
561 last_len = segs->len;
562 rc = qdisc_enqueue(segs, sch);
563 if (rc != NET_XMIT_SUCCESS) {
564 if (net_xmit_drop_count(rc))
565 qdisc_qstats_drop(sch);
566 } else {
567 nb++;
568 len += last_len;
569 }
570 segs = skb2;
571 }
572 sch->q.qlen += nb;
573 if (nb > 1)
574 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
575 }
576 return NET_XMIT_SUCCESS;
577}
578
579static unsigned int netem_drop(struct Qdisc *sch)
580{
581 struct netem_sched_data *q = qdisc_priv(sch);
582 unsigned int len;
583
584 len = qdisc_queue_drop(sch);
585
586 if (!len) {
587 struct rb_node *p = rb_first(&q->t_root);
588
589 if (p) {
590 struct sk_buff *skb = netem_rb_to_skb(p);
591
592 rb_erase(p, &q->t_root);
593 sch->q.qlen--;
594 skb->next = NULL;
595 skb->prev = NULL;
596 qdisc_qstats_backlog_dec(sch, skb);
597 kfree_skb(skb);
598 }
599 }
600 if (!len && q->qdisc && q->qdisc->ops->drop)
601 len = q->qdisc->ops->drop(q->qdisc);
602 if (len)
603 qdisc_qstats_drop(sch);
604
605 return len;
606}
607
608static struct sk_buff *netem_dequeue(struct Qdisc *sch)
609{
610 struct netem_sched_data *q = qdisc_priv(sch);
611 struct sk_buff *skb;
612 struct rb_node *p;
613
614 if (qdisc_is_throttled(sch))
615 return NULL;
616
617tfifo_dequeue:
618 skb = __skb_dequeue(&sch->q);
619 if (skb) {
620 qdisc_qstats_backlog_dec(sch, skb);
621deliver:
622 qdisc_unthrottled(sch);
623 qdisc_bstats_update(sch, skb);
624 return skb;
625 }
626 p = rb_first(&q->t_root);
627 if (p) {
628 psched_time_t time_to_send;
629
630 skb = netem_rb_to_skb(p);
631
632 /* if more time remaining? */
633 time_to_send = netem_skb_cb(skb)->time_to_send;
634 if (time_to_send <= psched_get_time()) {
635 rb_erase(p, &q->t_root);
636
637 sch->q.qlen--;
638 qdisc_qstats_backlog_dec(sch, skb);
639 skb->next = NULL;
640 skb->prev = NULL;
641 skb->tstamp = netem_skb_cb(skb)->tstamp_save;
642
643#ifdef CONFIG_NET_CLS_ACT
644 /*
645 * If it's at ingress let's pretend the delay is
646 * from the network (tstamp will be updated).
647 */
648 if (G_TC_FROM(skb->tc_verd) & AT_INGRESS)
649 skb->tstamp.tv64 = 0;
650#endif
651
652 if (q->qdisc) {
653 int err = qdisc_enqueue(skb, q->qdisc);
654
655 if (unlikely(err != NET_XMIT_SUCCESS)) {
656 if (net_xmit_drop_count(err)) {
657 qdisc_qstats_drop(sch);
658 qdisc_tree_reduce_backlog(sch, 1,
659 qdisc_pkt_len(skb));
660 }
661 }
662 goto tfifo_dequeue;
663 }
664 goto deliver;
665 }
666
667 if (q->qdisc) {
668 skb = q->qdisc->ops->dequeue(q->qdisc);
669 if (skb)
670 goto deliver;
671 }
672 qdisc_watchdog_schedule(&q->watchdog, time_to_send);
673 }
674
675 if (q->qdisc) {
676 skb = q->qdisc->ops->dequeue(q->qdisc);
677 if (skb)
678 goto deliver;
679 }
680 return NULL;
681}
682
683static void netem_reset(struct Qdisc *sch)
684{
685 struct netem_sched_data *q = qdisc_priv(sch);
686
687 qdisc_reset_queue(sch);
688 tfifo_reset(sch);
689 if (q->qdisc)
690 qdisc_reset(q->qdisc);
691 qdisc_watchdog_cancel(&q->watchdog);
692}
693
694static void dist_free(struct disttable *d)
695{
696 kvfree(d);
697}
698
699/*
700 * Distribution data is a variable size payload containing
701 * signed 16 bit values.
702 */
703static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
704{
705 struct netem_sched_data *q = qdisc_priv(sch);
706 size_t n = nla_len(attr)/sizeof(__s16);
707 const __s16 *data = nla_data(attr);
708 spinlock_t *root_lock;
709 struct disttable *d;
710 int i;
711 size_t s;
712
713 if (n > NETEM_DIST_MAX)
714 return -EINVAL;
715
716 s = sizeof(struct disttable) + n * sizeof(s16);
717 d = kmalloc(s, GFP_KERNEL | __GFP_NOWARN);
718 if (!d)
719 d = vmalloc(s);
720 if (!d)
721 return -ENOMEM;
722
723 d->size = n;
724 for (i = 0; i < n; i++)
725 d->table[i] = data[i];
726
727 root_lock = qdisc_root_sleeping_lock(sch);
728
729 spin_lock_bh(root_lock);
730 swap(q->delay_dist, d);
731 spin_unlock_bh(root_lock);
732
733 dist_free(d);
734 return 0;
735}
736
737static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
738{
739 const struct tc_netem_corr *c = nla_data(attr);
740
741 init_crandom(&q->delay_cor, c->delay_corr);
742 init_crandom(&q->loss_cor, c->loss_corr);
743 init_crandom(&q->dup_cor, c->dup_corr);
744}
745
746static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
747{
748 const struct tc_netem_reorder *r = nla_data(attr);
749
750 q->reorder = r->probability;
751 init_crandom(&q->reorder_cor, r->correlation);
752}
753
754static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
755{
756 const struct tc_netem_corrupt *r = nla_data(attr);
757
758 q->corrupt = r->probability;
759 init_crandom(&q->corrupt_cor, r->correlation);
760}
761
762static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
763{
764 const struct tc_netem_rate *r = nla_data(attr);
765
766 q->rate = r->rate;
767 q->packet_overhead = r->packet_overhead;
768 q->cell_size = r->cell_size;
769 q->cell_overhead = r->cell_overhead;
770 if (q->cell_size)
771 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
772 else
773 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
774}
775
776static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
777{
778 const struct nlattr *la;
779 int rem;
780
781 nla_for_each_nested(la, attr, rem) {
782 u16 type = nla_type(la);
783
784 switch (type) {
785 case NETEM_LOSS_GI: {
786 const struct tc_netem_gimodel *gi = nla_data(la);
787
788 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
789 pr_info("netem: incorrect gi model size\n");
790 return -EINVAL;
791 }
792
793 q->loss_model = CLG_4_STATES;
794
795 q->clg.state = TX_IN_GAP_PERIOD;
796 q->clg.a1 = gi->p13;
797 q->clg.a2 = gi->p31;
798 q->clg.a3 = gi->p32;
799 q->clg.a4 = gi->p14;
800 q->clg.a5 = gi->p23;
801 break;
802 }
803
804 case NETEM_LOSS_GE: {
805 const struct tc_netem_gemodel *ge = nla_data(la);
806
807 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
808 pr_info("netem: incorrect ge model size\n");
809 return -EINVAL;
810 }
811
812 q->loss_model = CLG_GILB_ELL;
813 q->clg.state = GOOD_STATE;
814 q->clg.a1 = ge->p;
815 q->clg.a2 = ge->r;
816 q->clg.a3 = ge->h;
817 q->clg.a4 = ge->k1;
818 break;
819 }
820
821 default:
822 pr_info("netem: unknown loss type %u\n", type);
823 return -EINVAL;
824 }
825 }
826
827 return 0;
828}
829
830static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
831 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
832 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
833 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
834 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
835 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
836 [TCA_NETEM_ECN] = { .type = NLA_U32 },
837 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
838};
839
840static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
841 const struct nla_policy *policy, int len)
842{
843 int nested_len = nla_len(nla) - NLA_ALIGN(len);
844
845 if (nested_len < 0) {
846 pr_info("netem: invalid attributes len %d\n", nested_len);
847 return -EINVAL;
848 }
849
850 if (nested_len >= nla_attr_size(0))
851 return nla_parse(tb, maxtype, nla_data(nla) + NLA_ALIGN(len),
852 nested_len, policy);
853
854 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
855 return 0;
856}
857
858/* Parse netlink message to set options */
859static int netem_change(struct Qdisc *sch, struct nlattr *opt)
860{
861 struct netem_sched_data *q = qdisc_priv(sch);
862 struct nlattr *tb[TCA_NETEM_MAX + 1];
863 struct tc_netem_qopt *qopt;
864 struct clgstate old_clg;
865 int old_loss_model = CLG_RANDOM;
866 int ret;
867
868 if (opt == NULL)
869 return -EINVAL;
870
871 qopt = nla_data(opt);
872 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
873 if (ret < 0)
874 return ret;
875
876 /* backup q->clg and q->loss_model */
877 old_clg = q->clg;
878 old_loss_model = q->loss_model;
879
880 if (tb[TCA_NETEM_LOSS]) {
881 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
882 if (ret) {
883 q->loss_model = old_loss_model;
884 return ret;
885 }
886 } else {
887 q->loss_model = CLG_RANDOM;
888 }
889
890 if (tb[TCA_NETEM_DELAY_DIST]) {
891 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
892 if (ret) {
893 /* recover clg and loss_model, in case of
894 * q->clg and q->loss_model were modified
895 * in get_loss_clg()
896 */
897 q->clg = old_clg;
898 q->loss_model = old_loss_model;
899 return ret;
900 }
901 }
902
903 sch->limit = qopt->limit;
904
905 q->latency = qopt->latency;
906 q->jitter = qopt->jitter;
907 q->limit = qopt->limit;
908 q->gap = qopt->gap;
909 q->counter = 0;
910 q->loss = qopt->loss;
911 q->duplicate = qopt->duplicate;
912
913 /* for compatibility with earlier versions.
914 * if gap is set, need to assume 100% probability
915 */
916 if (q->gap)
917 q->reorder = ~0;
918
919 if (tb[TCA_NETEM_CORR])
920 get_correlation(q, tb[TCA_NETEM_CORR]);
921
922 if (tb[TCA_NETEM_REORDER])
923 get_reorder(q, tb[TCA_NETEM_REORDER]);
924
925 if (tb[TCA_NETEM_CORRUPT])
926 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
927
928 if (tb[TCA_NETEM_RATE])
929 get_rate(q, tb[TCA_NETEM_RATE]);
930
931 if (tb[TCA_NETEM_RATE64])
932 q->rate = max_t(u64, q->rate,
933 nla_get_u64(tb[TCA_NETEM_RATE64]));
934
935 if (tb[TCA_NETEM_ECN])
936 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
937
938 return ret;
939}
940
941static int netem_init(struct Qdisc *sch, struct nlattr *opt)
942{
943 struct netem_sched_data *q = qdisc_priv(sch);
944 int ret;
945
946 if (!opt)
947 return -EINVAL;
948
949 qdisc_watchdog_init(&q->watchdog, sch);
950
951 q->loss_model = CLG_RANDOM;
952 ret = netem_change(sch, opt);
953 if (ret)
954 pr_info("netem: change failed\n");
955 return ret;
956}
957
958static void netem_destroy(struct Qdisc *sch)
959{
960 struct netem_sched_data *q = qdisc_priv(sch);
961
962 qdisc_watchdog_cancel(&q->watchdog);
963 if (q->qdisc)
964 qdisc_destroy(q->qdisc);
965 dist_free(q->delay_dist);
966}
967
968static int dump_loss_model(const struct netem_sched_data *q,
969 struct sk_buff *skb)
970{
971 struct nlattr *nest;
972
973 nest = nla_nest_start(skb, TCA_NETEM_LOSS);
974 if (nest == NULL)
975 goto nla_put_failure;
976
977 switch (q->loss_model) {
978 case CLG_RANDOM:
979 /* legacy loss model */
980 nla_nest_cancel(skb, nest);
981 return 0; /* no data */
982
983 case CLG_4_STATES: {
984 struct tc_netem_gimodel gi = {
985 .p13 = q->clg.a1,
986 .p31 = q->clg.a2,
987 .p32 = q->clg.a3,
988 .p14 = q->clg.a4,
989 .p23 = q->clg.a5,
990 };
991
992 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
993 goto nla_put_failure;
994 break;
995 }
996 case CLG_GILB_ELL: {
997 struct tc_netem_gemodel ge = {
998 .p = q->clg.a1,
999 .r = q->clg.a2,
1000 .h = q->clg.a3,
1001 .k1 = q->clg.a4,
1002 };
1003
1004 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1005 goto nla_put_failure;
1006 break;
1007 }
1008 }
1009
1010 nla_nest_end(skb, nest);
1011 return 0;
1012
1013nla_put_failure:
1014 nla_nest_cancel(skb, nest);
1015 return -1;
1016}
1017
1018static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1019{
1020 const struct netem_sched_data *q = qdisc_priv(sch);
1021 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1022 struct tc_netem_qopt qopt;
1023 struct tc_netem_corr cor;
1024 struct tc_netem_reorder reorder;
1025 struct tc_netem_corrupt corrupt;
1026 struct tc_netem_rate rate;
1027
1028 qopt.latency = q->latency;
1029 qopt.jitter = q->jitter;
1030 qopt.limit = q->limit;
1031 qopt.loss = q->loss;
1032 qopt.gap = q->gap;
1033 qopt.duplicate = q->duplicate;
1034 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1035 goto nla_put_failure;
1036
1037 cor.delay_corr = q->delay_cor.rho;
1038 cor.loss_corr = q->loss_cor.rho;
1039 cor.dup_corr = q->dup_cor.rho;
1040 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1041 goto nla_put_failure;
1042
1043 reorder.probability = q->reorder;
1044 reorder.correlation = q->reorder_cor.rho;
1045 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1046 goto nla_put_failure;
1047
1048 corrupt.probability = q->corrupt;
1049 corrupt.correlation = q->corrupt_cor.rho;
1050 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1051 goto nla_put_failure;
1052
1053 if (q->rate >= (1ULL << 32)) {
1054 if (nla_put_u64(skb, TCA_NETEM_RATE64, q->rate))
1055 goto nla_put_failure;
1056 rate.rate = ~0U;
1057 } else {
1058 rate.rate = q->rate;
1059 }
1060 rate.packet_overhead = q->packet_overhead;
1061 rate.cell_size = q->cell_size;
1062 rate.cell_overhead = q->cell_overhead;
1063 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1064 goto nla_put_failure;
1065
1066 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1067 goto nla_put_failure;
1068
1069 if (dump_loss_model(q, skb) != 0)
1070 goto nla_put_failure;
1071
1072 return nla_nest_end(skb, nla);
1073
1074nla_put_failure:
1075 nlmsg_trim(skb, nla);
1076 return -1;
1077}
1078
1079static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1080 struct sk_buff *skb, struct tcmsg *tcm)
1081{
1082 struct netem_sched_data *q = qdisc_priv(sch);
1083
1084 if (cl != 1 || !q->qdisc) /* only one class */
1085 return -ENOENT;
1086
1087 tcm->tcm_handle |= TC_H_MIN(1);
1088 tcm->tcm_info = q->qdisc->handle;
1089
1090 return 0;
1091}
1092
1093static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1094 struct Qdisc **old)
1095{
1096 struct netem_sched_data *q = qdisc_priv(sch);
1097
1098 *old = qdisc_replace(sch, new, &q->qdisc);
1099 return 0;
1100}
1101
1102static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1103{
1104 struct netem_sched_data *q = qdisc_priv(sch);
1105 return q->qdisc;
1106}
1107
1108static unsigned long netem_get(struct Qdisc *sch, u32 classid)
1109{
1110 return 1;
1111}
1112
1113static void netem_put(struct Qdisc *sch, unsigned long arg)
1114{
1115}
1116
1117static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1118{
1119 if (!walker->stop) {
1120 if (walker->count >= walker->skip)
1121 if (walker->fn(sch, 1, walker) < 0) {
1122 walker->stop = 1;
1123 return;
1124 }
1125 walker->count++;
1126 }
1127}
1128
1129static const struct Qdisc_class_ops netem_class_ops = {
1130 .graft = netem_graft,
1131 .leaf = netem_leaf,
1132 .get = netem_get,
1133 .put = netem_put,
1134 .walk = netem_walk,
1135 .dump = netem_dump_class,
1136};
1137
1138static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1139 .id = "netem",
1140 .cl_ops = &netem_class_ops,
1141 .priv_size = sizeof(struct netem_sched_data),
1142 .enqueue = netem_enqueue,
1143 .dequeue = netem_dequeue,
1144 .peek = qdisc_peek_dequeued,
1145 .drop = netem_drop,
1146 .init = netem_init,
1147 .reset = netem_reset,
1148 .destroy = netem_destroy,
1149 .change = netem_change,
1150 .dump = netem_dump,
1151 .owner = THIS_MODULE,
1152};
1153
1154
1155static int __init netem_module_init(void)
1156{
1157 pr_info("netem: version " VERSION "\n");
1158 return register_qdisc(&netem_qdisc_ops);
1159}
1160static void __exit netem_module_exit(void)
1161{
1162 unregister_qdisc(&netem_qdisc_ops);
1163}
1164module_init(netem_module_init)
1165module_exit(netem_module_exit)
1166MODULE_LICENSE("GPL");