1 // SPDX-License-Identifier: GPL-2.0-only
3 * net/sched/sch_netem.c Network emulator
5 * Many of the algorithms and ideas for this came from
6 * NIST Net which is not copyrighted.
8 * Authors: Stephen Hemminger <shemminger@osdl.org>
9 * Catalin(ux aka Dino) BOIE <catab at umbrella dot ro>
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>
24 #include <net/netlink.h>
25 #include <net/pkt_sched.h>
26 #include <net/inet_ecn.h>
30 /* Network Emulation Queuing algorithm.
31 ====================================
33 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
34 Network Emulation Tool
35 [2] Luigi Rizzo, DummyNet for FreeBSD
37 ----------------------------------------------------------------
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.
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.
52 Correlated Loss Generator models
54 Added generation of correlated loss according to the
55 "Gilbert-Elliot" model, a 4-state markov model.
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]
63 Authors: Stefano Salsano <stefano.salsano at uniroma2.it
64 Fabio Ludovici <fabio.ludovici at yahoo.it>
72 struct netem_sched_data {
73 /* internal t(ime)fifo qdisc uses t_root and sch->limit */
74 struct rb_root t_root;
76 /* a linear queue; reduces rbtree rebalancing when jitter is low */
77 struct sk_buff *t_head;
78 struct sk_buff *t_tail;
80 /* optional qdisc for classful handling (NULL at netem init) */
83 struct qdisc_watchdog watchdog;
99 struct reciprocal_value cell_size_reciprocal;
105 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
107 struct disttable *delay_dist;
116 TX_IN_GAP_PERIOD = 1,
119 LOST_IN_BURST_PERIOD,
127 /* Correlated Loss Generation models */
129 /* state of the Markov chain */
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 */
140 struct tc_netem_slot slot_config;
147 struct disttable *slot_dist;
150 /* Time stamp put into socket buffer control block
151 * Only valid when skbs are in our internal t(ime)fifo queue.
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.
157 struct netem_skb_cb {
161 static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
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;
168 /* init_crandom - initialize correlated random number generator
169 * Use entropy source for initial seed.
171 static void init_crandom(struct crndstate *state, unsigned long rho)
174 state->last = prandom_u32();
177 /* get_crandom - correlated random number generator
178 * Next number depends on last value.
179 * rho is scaled to avoid floating point.
181 static u32 get_crandom(struct crndstate *state)
184 unsigned long answer;
186 if (!state || state->rho == 0) /* no correlation */
187 return prandom_u32();
189 value = prandom_u32();
190 rho = (u64)state->rho + 1;
191 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
192 state->last = answer;
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.
200 static bool loss_4state(struct netem_sched_data *q)
202 struct clgstate *clg = &q->clg;
203 u32 rnd = prandom_u32();
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_BURST_PERIOD => isolated losses within a gap period
212 * LOST_IN_GAP_PERIOD => lost packets within a burst period
213 * TX_IN_GAP_PERIOD => successfully transmitted packets within a burst period
215 switch (clg->state) {
216 case TX_IN_GAP_PERIOD:
218 clg->state = LOST_IN_BURST_PERIOD;
220 } else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {
221 clg->state = LOST_IN_GAP_PERIOD;
223 } else if (clg->a1 + clg->a4 < rnd) {
224 clg->state = TX_IN_GAP_PERIOD;
228 case TX_IN_BURST_PERIOD:
230 clg->state = LOST_IN_GAP_PERIOD;
233 clg->state = TX_IN_BURST_PERIOD;
237 case LOST_IN_GAP_PERIOD:
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_GAP_PERIOD;
247 case LOST_IN_BURST_PERIOD:
248 clg->state = TX_IN_GAP_PERIOD;
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)
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.
265 static bool loss_gilb_ell(struct netem_sched_data *q)
267 struct clgstate *clg = &q->clg;
269 switch (clg->state) {
271 if (prandom_u32() < clg->a1)
272 clg->state = BAD_STATE;
273 if (prandom_u32() < clg->a4)
277 if (prandom_u32() < clg->a2)
278 clg->state = GOOD_STATE;
279 if (prandom_u32() > clg->a3)
286 static bool loss_event(struct netem_sched_data *q)
288 switch (q->loss_model) {
290 /* Random packet drop 0 => none, ~0 => all */
291 return q->loss && q->loss >= get_crandom(&q->loss_cor);
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
299 return loss_4state(q);
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
307 return loss_gilb_ell(q);
310 return false; /* not reached */
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.
318 static s64 tabledist(s64 mu, s32 sigma,
319 struct crndstate *state,
320 const struct disttable *dist)
329 rnd = get_crandom(state);
331 /* default uniform distribution */
333 return ((rnd % (2 * sigma)) + mu) - sigma;
335 t = dist->table[rnd % dist->size];
336 x = (sigma % NETEM_DIST_SCALE) * t;
338 x += NETEM_DIST_SCALE/2;
340 x -= NETEM_DIST_SCALE/2;
342 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
345 static u64 packet_time_ns(u64 len, const struct netem_sched_data *q)
347 len += q->packet_overhead;
350 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
352 if (len > cells * q->cell_size) /* extra cell needed for remainder */
354 len = cells * (q->cell_size + q->cell_overhead);
357 return div64_u64(len * NSEC_PER_SEC, q->rate);
360 static void tfifo_reset(struct Qdisc *sch)
362 struct netem_sched_data *q = qdisc_priv(sch);
363 struct rb_node *p = rb_first(&q->t_root);
366 struct sk_buff *skb = rb_to_skb(p);
369 rb_erase(&skb->rbnode, &q->t_root);
370 rtnl_kfree_skbs(skb, skb);
373 rtnl_kfree_skbs(q->t_head, q->t_tail);
378 static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
380 struct netem_sched_data *q = qdisc_priv(sch);
381 u64 tnext = netem_skb_cb(nskb)->time_to_send;
383 if (!q->t_tail || tnext >= netem_skb_cb(q->t_tail)->time_to_send) {
385 q->t_tail->next = nskb;
390 struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
396 skb = rb_to_skb(parent);
397 if (tnext >= netem_skb_cb(skb)->time_to_send)
398 p = &parent->rb_right;
400 p = &parent->rb_left;
402 rb_link_node(&nskb->rbnode, parent, p);
403 rb_insert_color(&nskb->rbnode, &q->t_root);
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
412 static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
413 struct sk_buff **to_free)
415 struct sk_buff *segs;
416 netdev_features_t features = netif_skb_features(skb);
418 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
420 if (IS_ERR_OR_NULL(segs)) {
421 qdisc_drop(skb, sch, to_free);
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.
434 static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
435 struct sk_buff **to_free)
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 len = 0, last_len, prev_len = qdisc_pkt_len(skb);
445 int rc = NET_XMIT_SUCCESS;
446 int rc_drop = NET_XMIT_DROP;
448 /* Do not fool qdisc_drop_all() */
451 /* Random duplication */
452 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
457 if (q->ecn && INET_ECN_set_ce(skb))
458 qdisc_qstats_drop(sch); /* mark packet */
463 qdisc_qstats_drop(sch);
464 __qdisc_drop(skb, to_free);
465 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
468 /* If a delay is expected, orphan the skb. (orphaning usually takes
469 * place at TX completion time, so _before_ the link transit delay)
471 if (q->latency || q->jitter || q->rate)
472 skb_orphan_partial(skb);
475 * If we need to duplicate packet, then re-insert at top of the
476 * qdisc tree, since parent queuer expects that only one
477 * skb will be queued.
479 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
480 struct Qdisc *rootq = qdisc_root(sch);
481 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
484 rootq->enqueue(skb2, rootq, to_free);
485 q->duplicate = dupsave;
486 rc_drop = NET_XMIT_SUCCESS;
490 * Randomized packet corruption.
491 * Make copy if needed since we are modifying
492 * If packet is going to be hardware checksummed, then
493 * do it now in software before we mangle it.
495 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
496 if (skb_is_gso(skb)) {
497 segs = netem_segment(skb, sch, to_free);
507 skb = skb_unshare(skb, GFP_ATOMIC);
508 if (unlikely(!skb)) {
509 qdisc_qstats_drop(sch);
512 if (skb->ip_summed == CHECKSUM_PARTIAL &&
513 skb_checksum_help(skb)) {
514 qdisc_drop(skb, sch, to_free);
518 skb->data[prandom_u32() % skb_headlen(skb)] ^=
519 1<<(prandom_u32() % 8);
522 if (unlikely(sch->q.qlen >= sch->limit)) {
523 qdisc_drop_all(skb, sch, to_free);
527 qdisc_qstats_backlog_inc(sch, skb);
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)) {
536 delay = tabledist(q->latency, q->jitter,
537 &q->delay_cor, q->delay_dist);
539 now = ktime_get_ns();
542 struct netem_skb_cb *last = NULL;
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;
550 t_skb = skb_rb_last(&q->t_root);
551 t_last = netem_skb_cb(t_skb);
553 t_last->time_to_send > last->time_to_send)
557 struct netem_skb_cb *t_last =
558 netem_skb_cb(q->t_tail);
561 t_last->time_to_send > last->time_to_send)
567 * Last packet in queue is reference point (now),
568 * calculate this time bonus and subtract
571 delay -= last->time_to_send - now;
572 delay = max_t(s64, 0, delay);
573 now = last->time_to_send;
576 delay += packet_time_ns(qdisc_pkt_len(skb), q);
579 cb->time_to_send = now + delay;
581 tfifo_enqueue(skb, sch);
584 * Do re-ordering by putting one out of N packets at the front
587 cb->time_to_send = ktime_get_ns();
590 __qdisc_enqueue_head(skb, &sch->q);
591 sch->qstats.requeues++;
598 skb_mark_not_on_list(segs);
599 qdisc_skb_cb(segs)->pkt_len = segs->len;
600 last_len = segs->len;
601 rc = qdisc_enqueue(segs, sch, to_free);
602 if (rc != NET_XMIT_SUCCESS) {
603 if (net_xmit_drop_count(rc))
604 qdisc_qstats_drop(sch);
613 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
615 return NET_XMIT_SUCCESS;
618 /* Delay the next round with a new future slot with a
619 * correct number of bytes and packets.
622 static void get_slot_next(struct netem_sched_data *q, u64 now)
627 next_delay = q->slot_config.min_delay +
629 (q->slot_config.max_delay -
630 q->slot_config.min_delay) >> 32);
632 next_delay = tabledist(q->slot_config.dist_delay,
633 (s32)(q->slot_config.dist_jitter),
636 q->slot.slot_next = now + next_delay;
637 q->slot.packets_left = q->slot_config.max_packets;
638 q->slot.bytes_left = q->slot_config.max_bytes;
641 static struct sk_buff *netem_peek(struct netem_sched_data *q)
643 struct sk_buff *skb = skb_rb_first(&q->t_root);
651 t1 = netem_skb_cb(skb)->time_to_send;
652 t2 = netem_skb_cb(q->t_head)->time_to_send;
658 static void netem_erase_head(struct netem_sched_data *q, struct sk_buff *skb)
660 if (skb == q->t_head) {
661 q->t_head = skb->next;
665 rb_erase(&skb->rbnode, &q->t_root);
669 static struct sk_buff *netem_dequeue(struct Qdisc *sch)
671 struct netem_sched_data *q = qdisc_priv(sch);
675 skb = __qdisc_dequeue_head(&sch->q);
677 qdisc_qstats_backlog_dec(sch, skb);
679 qdisc_bstats_update(sch, skb);
685 u64 now = ktime_get_ns();
687 /* if more time remaining? */
688 time_to_send = netem_skb_cb(skb)->time_to_send;
689 if (q->slot.slot_next && q->slot.slot_next < time_to_send)
690 get_slot_next(q, now);
692 if (time_to_send <= now && q->slot.slot_next <= now) {
693 netem_erase_head(q, skb);
695 qdisc_qstats_backlog_dec(sch, skb);
698 /* skb->dev shares skb->rbnode area,
699 * we need to restore its value.
701 skb->dev = qdisc_dev(sch);
703 if (q->slot.slot_next) {
704 q->slot.packets_left--;
705 q->slot.bytes_left -= qdisc_pkt_len(skb);
706 if (q->slot.packets_left <= 0 ||
707 q->slot.bytes_left <= 0)
708 get_slot_next(q, now);
712 unsigned int pkt_len = qdisc_pkt_len(skb);
713 struct sk_buff *to_free = NULL;
716 err = qdisc_enqueue(skb, q->qdisc, &to_free);
717 kfree_skb_list(to_free);
718 if (err != NET_XMIT_SUCCESS &&
719 net_xmit_drop_count(err)) {
720 qdisc_qstats_drop(sch);
721 qdisc_tree_reduce_backlog(sch, 1,
730 skb = q->qdisc->ops->dequeue(q->qdisc);
735 qdisc_watchdog_schedule_ns(&q->watchdog,
741 skb = q->qdisc->ops->dequeue(q->qdisc);
748 static void netem_reset(struct Qdisc *sch)
750 struct netem_sched_data *q = qdisc_priv(sch);
752 qdisc_reset_queue(sch);
755 qdisc_reset(q->qdisc);
756 qdisc_watchdog_cancel(&q->watchdog);
759 static void dist_free(struct disttable *d)
765 * Distribution data is a variable size payload containing
766 * signed 16 bit values.
769 static int get_dist_table(struct Qdisc *sch, struct disttable **tbl,
770 const struct nlattr *attr)
772 size_t n = nla_len(attr)/sizeof(__s16);
773 const __s16 *data = nla_data(attr);
774 spinlock_t *root_lock;
778 if (n > NETEM_DIST_MAX)
781 d = kvmalloc(sizeof(struct disttable) + n * sizeof(s16), GFP_KERNEL);
786 for (i = 0; i < n; i++)
787 d->table[i] = data[i];
789 root_lock = qdisc_root_sleeping_lock(sch);
791 spin_lock_bh(root_lock);
793 spin_unlock_bh(root_lock);
799 static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
801 const struct tc_netem_slot *c = nla_data(attr);
804 if (q->slot_config.max_packets == 0)
805 q->slot_config.max_packets = INT_MAX;
806 if (q->slot_config.max_bytes == 0)
807 q->slot_config.max_bytes = INT_MAX;
808 q->slot.packets_left = q->slot_config.max_packets;
809 q->slot.bytes_left = q->slot_config.max_bytes;
810 if (q->slot_config.min_delay | q->slot_config.max_delay |
811 q->slot_config.dist_jitter)
812 q->slot.slot_next = ktime_get_ns();
814 q->slot.slot_next = 0;
817 static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
819 const struct tc_netem_corr *c = nla_data(attr);
821 init_crandom(&q->delay_cor, c->delay_corr);
822 init_crandom(&q->loss_cor, c->loss_corr);
823 init_crandom(&q->dup_cor, c->dup_corr);
826 static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
828 const struct tc_netem_reorder *r = nla_data(attr);
830 q->reorder = r->probability;
831 init_crandom(&q->reorder_cor, r->correlation);
834 static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
836 const struct tc_netem_corrupt *r = nla_data(attr);
838 q->corrupt = r->probability;
839 init_crandom(&q->corrupt_cor, r->correlation);
842 static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
844 const struct tc_netem_rate *r = nla_data(attr);
847 q->packet_overhead = r->packet_overhead;
848 q->cell_size = r->cell_size;
849 q->cell_overhead = r->cell_overhead;
851 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
853 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
856 static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
858 const struct nlattr *la;
861 nla_for_each_nested(la, attr, rem) {
862 u16 type = nla_type(la);
865 case NETEM_LOSS_GI: {
866 const struct tc_netem_gimodel *gi = nla_data(la);
868 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
869 pr_info("netem: incorrect gi model size\n");
873 q->loss_model = CLG_4_STATES;
875 q->clg.state = TX_IN_GAP_PERIOD;
884 case NETEM_LOSS_GE: {
885 const struct tc_netem_gemodel *ge = nla_data(la);
887 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
888 pr_info("netem: incorrect ge model size\n");
892 q->loss_model = CLG_GILB_ELL;
893 q->clg.state = GOOD_STATE;
902 pr_info("netem: unknown loss type %u\n", type);
910 static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
911 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
912 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
913 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
914 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
915 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
916 [TCA_NETEM_ECN] = { .type = NLA_U32 },
917 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
918 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
919 [TCA_NETEM_JITTER64] = { .type = NLA_S64 },
920 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
923 static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
924 const struct nla_policy *policy, int len)
926 int nested_len = nla_len(nla) - NLA_ALIGN(len);
928 if (nested_len < 0) {
929 pr_info("netem: invalid attributes len %d\n", nested_len);
933 if (nested_len >= nla_attr_size(0))
934 return nla_parse_deprecated(tb, maxtype,
935 nla_data(nla) + NLA_ALIGN(len),
936 nested_len, policy, NULL);
938 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
942 /* Parse netlink message to set options */
943 static int netem_change(struct Qdisc *sch, struct nlattr *opt,
944 struct netlink_ext_ack *extack)
946 struct netem_sched_data *q = qdisc_priv(sch);
947 struct nlattr *tb[TCA_NETEM_MAX + 1];
948 struct tc_netem_qopt *qopt;
949 struct clgstate old_clg;
950 int old_loss_model = CLG_RANDOM;
956 qopt = nla_data(opt);
957 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
961 /* backup q->clg and q->loss_model */
963 old_loss_model = q->loss_model;
965 if (tb[TCA_NETEM_LOSS]) {
966 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
968 q->loss_model = old_loss_model;
972 q->loss_model = CLG_RANDOM;
975 if (tb[TCA_NETEM_DELAY_DIST]) {
976 ret = get_dist_table(sch, &q->delay_dist,
977 tb[TCA_NETEM_DELAY_DIST]);
979 goto get_table_failure;
982 if (tb[TCA_NETEM_SLOT_DIST]) {
983 ret = get_dist_table(sch, &q->slot_dist,
984 tb[TCA_NETEM_SLOT_DIST]);
986 goto get_table_failure;
989 sch->limit = qopt->limit;
991 q->latency = PSCHED_TICKS2NS(qopt->latency);
992 q->jitter = PSCHED_TICKS2NS(qopt->jitter);
993 q->limit = qopt->limit;
996 q->loss = qopt->loss;
997 q->duplicate = qopt->duplicate;
999 /* for compatibility with earlier versions.
1000 * if gap is set, need to assume 100% probability
1005 if (tb[TCA_NETEM_CORR])
1006 get_correlation(q, tb[TCA_NETEM_CORR]);
1008 if (tb[TCA_NETEM_REORDER])
1009 get_reorder(q, tb[TCA_NETEM_REORDER]);
1011 if (tb[TCA_NETEM_CORRUPT])
1012 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
1014 if (tb[TCA_NETEM_RATE])
1015 get_rate(q, tb[TCA_NETEM_RATE]);
1017 if (tb[TCA_NETEM_RATE64])
1018 q->rate = max_t(u64, q->rate,
1019 nla_get_u64(tb[TCA_NETEM_RATE64]));
1021 if (tb[TCA_NETEM_LATENCY64])
1022 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
1024 if (tb[TCA_NETEM_JITTER64])
1025 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
1027 if (tb[TCA_NETEM_ECN])
1028 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
1030 if (tb[TCA_NETEM_SLOT])
1031 get_slot(q, tb[TCA_NETEM_SLOT]);
1036 /* recover clg and loss_model, in case of
1037 * q->clg and q->loss_model were modified
1041 q->loss_model = old_loss_model;
1045 static int netem_init(struct Qdisc *sch, struct nlattr *opt,
1046 struct netlink_ext_ack *extack)
1048 struct netem_sched_data *q = qdisc_priv(sch);
1051 qdisc_watchdog_init(&q->watchdog, sch);
1056 q->loss_model = CLG_RANDOM;
1057 ret = netem_change(sch, opt, extack);
1059 pr_info("netem: change failed\n");
1063 static void netem_destroy(struct Qdisc *sch)
1065 struct netem_sched_data *q = qdisc_priv(sch);
1067 qdisc_watchdog_cancel(&q->watchdog);
1069 qdisc_put(q->qdisc);
1070 dist_free(q->delay_dist);
1071 dist_free(q->slot_dist);
1074 static int dump_loss_model(const struct netem_sched_data *q,
1075 struct sk_buff *skb)
1077 struct nlattr *nest;
1079 nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS);
1081 goto nla_put_failure;
1083 switch (q->loss_model) {
1085 /* legacy loss model */
1086 nla_nest_cancel(skb, nest);
1087 return 0; /* no data */
1089 case CLG_4_STATES: {
1090 struct tc_netem_gimodel gi = {
1098 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
1099 goto nla_put_failure;
1102 case CLG_GILB_ELL: {
1103 struct tc_netem_gemodel ge = {
1110 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1111 goto nla_put_failure;
1116 nla_nest_end(skb, nest);
1120 nla_nest_cancel(skb, nest);
1124 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1126 const struct netem_sched_data *q = qdisc_priv(sch);
1127 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1128 struct tc_netem_qopt qopt;
1129 struct tc_netem_corr cor;
1130 struct tc_netem_reorder reorder;
1131 struct tc_netem_corrupt corrupt;
1132 struct tc_netem_rate rate;
1133 struct tc_netem_slot slot;
1135 qopt.latency = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->latency),
1137 qopt.jitter = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->jitter),
1139 qopt.limit = q->limit;
1140 qopt.loss = q->loss;
1142 qopt.duplicate = q->duplicate;
1143 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1144 goto nla_put_failure;
1146 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
1147 goto nla_put_failure;
1149 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
1150 goto nla_put_failure;
1152 cor.delay_corr = q->delay_cor.rho;
1153 cor.loss_corr = q->loss_cor.rho;
1154 cor.dup_corr = q->dup_cor.rho;
1155 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1156 goto nla_put_failure;
1158 reorder.probability = q->reorder;
1159 reorder.correlation = q->reorder_cor.rho;
1160 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1161 goto nla_put_failure;
1163 corrupt.probability = q->corrupt;
1164 corrupt.correlation = q->corrupt_cor.rho;
1165 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1166 goto nla_put_failure;
1168 if (q->rate >= (1ULL << 32)) {
1169 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1171 goto nla_put_failure;
1174 rate.rate = q->rate;
1176 rate.packet_overhead = q->packet_overhead;
1177 rate.cell_size = q->cell_size;
1178 rate.cell_overhead = q->cell_overhead;
1179 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1180 goto nla_put_failure;
1182 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1183 goto nla_put_failure;
1185 if (dump_loss_model(q, skb) != 0)
1186 goto nla_put_failure;
1188 if (q->slot_config.min_delay | q->slot_config.max_delay |
1189 q->slot_config.dist_jitter) {
1190 slot = q->slot_config;
1191 if (slot.max_packets == INT_MAX)
1192 slot.max_packets = 0;
1193 if (slot.max_bytes == INT_MAX)
1195 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
1196 goto nla_put_failure;
1199 return nla_nest_end(skb, nla);
1202 nlmsg_trim(skb, nla);
1206 static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1207 struct sk_buff *skb, struct tcmsg *tcm)
1209 struct netem_sched_data *q = qdisc_priv(sch);
1211 if (cl != 1 || !q->qdisc) /* only one class */
1214 tcm->tcm_handle |= TC_H_MIN(1);
1215 tcm->tcm_info = q->qdisc->handle;
1220 static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1221 struct Qdisc **old, struct netlink_ext_ack *extack)
1223 struct netem_sched_data *q = qdisc_priv(sch);
1225 *old = qdisc_replace(sch, new, &q->qdisc);
1229 static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1231 struct netem_sched_data *q = qdisc_priv(sch);
1235 static unsigned long netem_find(struct Qdisc *sch, u32 classid)
1240 static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1242 if (!walker->stop) {
1243 if (walker->count >= walker->skip)
1244 if (walker->fn(sch, 1, walker) < 0) {
1252 static const struct Qdisc_class_ops netem_class_ops = {
1253 .graft = netem_graft,
1257 .dump = netem_dump_class,
1260 static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1262 .cl_ops = &netem_class_ops,
1263 .priv_size = sizeof(struct netem_sched_data),
1264 .enqueue = netem_enqueue,
1265 .dequeue = netem_dequeue,
1266 .peek = qdisc_peek_dequeued,
1268 .reset = netem_reset,
1269 .destroy = netem_destroy,
1270 .change = netem_change,
1272 .owner = THIS_MODULE,
1276 static int __init netem_module_init(void)
1278 pr_info("netem: version " VERSION "\n");
1279 return register_qdisc(&netem_qdisc_ops);
1281 static void __exit netem_module_exit(void)
1283 unregister_qdisc(&netem_qdisc_ops);
1285 module_init(netem_module_init)
1286 module_exit(netem_module_exit)
1287 MODULE_LICENSE("GPL");