Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1309 insertions, 0 deletions

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
new file mode 100644
index 0000000000..4ad39a4a3c
--- /dev/null
+++ b/net/sched/sch_netem.c
@@ -0,0 +1,1309 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * net/sched/sch_netem.c	Network emulator
+ *
+ *  		Many of the algorithms and ideas for this came from
+ *		NIST Net which is not copyrighted.
+ *
+ * Authors:	Stephen Hemminger <shemminger@osdl.org>
+ *		Catalin(ux aka Dino) BOIE <catab at umbrella dot ro>
+ */
+
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <linux/vmalloc.h>
+#include <linux/rtnetlink.h>
+#include <linux/reciprocal_div.h>
+#include <linux/rbtree.h>
+
+#include <net/gso.h>
+#include <net/netlink.h>
+#include <net/pkt_sched.h>
+#include <net/inet_ecn.h>
+
+#define VERSION "1.3"
+
+/*	Network Emulation Queuing algorithm.
+	====================================
+
+	Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
+		 Network Emulation Tool
+		 [2] Luigi Rizzo, DummyNet for FreeBSD
+
+	 ----------------------------------------------------------------
+
+	 This started out as a simple way to delay outgoing packets to
+	 test TCP but has grown to include most of the functionality
+	 of a full blown network emulator like NISTnet. It can delay
+	 packets and add random jitter (and correlation). The random
+	 distribution can be loaded from a table as well to provide
+	 normal, Pareto, or experimental curves. Packet loss,
+	 duplication, and reordering can also be emulated.
+
+	 This qdisc does not do classification that can be handled in
+	 layering other disciplines.  It does not need to do bandwidth
+	 control either since that can be handled by using token
+	 bucket or other rate control.
+
+     Correlated Loss Generator models
+
+	Added generation of correlated loss according to the
+	"Gilbert-Elliot" model, a 4-state markov model.
+
+	References:
+	[1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG
+	[2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
+	and intuitive loss model for packet networks and its implementation
+	in the Netem module in the Linux kernel", available in [1]
+
+	Authors: Stefano Salsano <stefano.salsano at uniroma2.it
+		 Fabio Ludovici <fabio.ludovici at yahoo.it>
+*/
+
+struct disttable {
+	u32  size;
+	s16 table[];
+};
+
+struct netem_sched_data {
+	/* internal t(ime)fifo qdisc uses t_root and sch->limit */
+	struct rb_root t_root;
+
+	/* a linear queue; reduces rbtree rebalancing when jitter is low */
+	struct sk_buff	*t_head;
+	struct sk_buff	*t_tail;
+
+	/* optional qdisc for classful handling (NULL at netem init) */
+	struct Qdisc	*qdisc;
+
+	struct qdisc_watchdog watchdog;
+
+	s64 latency;
+	s64 jitter;
+
+	u32 loss;
+	u32 ecn;
+	u32 limit;
+	u32 counter;
+	u32 gap;
+	u32 duplicate;
+	u32 reorder;
+	u32 corrupt;
+	u64 rate;
+	s32 packet_overhead;
+	u32 cell_size;
+	struct reciprocal_value cell_size_reciprocal;
+	s32 cell_overhead;
+
+	struct crndstate {
+		u32 last;
+		u32 rho;
+	} delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
+
+	struct prng  {
+		u64 seed;
+		struct rnd_state prng_state;
+	} prng;
+
+	struct disttable *delay_dist;
+
+	enum  {
+		CLG_RANDOM,
+		CLG_4_STATES,
+		CLG_GILB_ELL,
+	} loss_model;
+
+	enum {
+		TX_IN_GAP_PERIOD = 1,
+		TX_IN_BURST_PERIOD,
+		LOST_IN_GAP_PERIOD,
+		LOST_IN_BURST_PERIOD,
+	} _4_state_model;
+
+	enum {
+		GOOD_STATE = 1,
+		BAD_STATE,
+	} GE_state_model;
+
+	/* Correlated Loss Generation models */
+	struct clgstate {
+		/* state of the Markov chain */
+		u8 state;
+
+		/* 4-states and Gilbert-Elliot models */
+		u32 a1;	/* p13 for 4-states or p for GE */
+		u32 a2;	/* p31 for 4-states or r for GE */
+		u32 a3;	/* p32 for 4-states or h for GE */
+		u32 a4;	/* p14 for 4-states or 1-k for GE */
+		u32 a5; /* p23 used only in 4-states */
+	} clg;
+
+	struct tc_netem_slot slot_config;
+	struct slotstate {
+		u64 slot_next;
+		s32 packets_left;
+		s32 bytes_left;
+	} slot;
+
+	struct disttable *slot_dist;
+};
+
+/* Time stamp put into socket buffer control block
+ * Only valid when skbs are in our internal t(ime)fifo queue.
+ *
+ * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,
+ * and skb->next & skb->prev are scratch space for a qdisc,
+ * we save skb->tstamp value in skb->cb[] before destroying it.
+ */
+struct netem_skb_cb {
+	u64	        time_to_send;
+};
+
+static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
+{
+	/* we assume we can use skb next/prev/tstamp as storage for rb_node */
+	qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb));
+	return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
+}
+
+/* init_crandom - initialize correlated random number generator
+ * Use entropy source for initial seed.
+ */
+static void init_crandom(struct crndstate *state, unsigned long rho)
+{
+	state->rho = rho;
+	state->last = get_random_u32();
+}
+
+/* get_crandom - correlated random number generator
+ * Next number depends on last value.
+ * rho is scaled to avoid floating point.
+ */
+static u32 get_crandom(struct crndstate *state, struct prng *p)
+{
+	u64 value, rho;
+	unsigned long answer;
+	struct rnd_state *s = &p->prng_state;
+
+	if (!state || state->rho == 0)	/* no correlation */
+		return prandom_u32_state(s);
+
+	value = prandom_u32_state(s);
+	rho = (u64)state->rho + 1;
+	answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
+	state->last = answer;
+	return answer;
+}
+
+/* loss_4state - 4-state model loss generator
+ * Generates losses according to the 4-state Markov chain adopted in
+ * the GI (General and Intuitive) loss model.
+ */
+static bool loss_4state(struct netem_sched_data *q)
+{
+	struct clgstate *clg = &q->clg;
+	u32 rnd = prandom_u32_state(&q->prng.prng_state);
+
+	/*
+	 * Makes a comparison between rnd and the transition
+	 * probabilities outgoing from the current state, then decides the
+	 * next state and if the next packet has to be transmitted or lost.
+	 * The four states correspond to:
+	 *   TX_IN_GAP_PERIOD => successfully transmitted packets within a gap period
+	 *   LOST_IN_GAP_PERIOD => isolated losses within a gap period
+	 *   LOST_IN_BURST_PERIOD => lost packets within a burst period
+	 *   TX_IN_BURST_PERIOD => successfully transmitted packets within a burst period
+	 */
+	switch (clg->state) {
+	case TX_IN_GAP_PERIOD:
+		if (rnd < clg->a4) {
+			clg->state = LOST_IN_GAP_PERIOD;
+			return true;
+		} else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {
+			clg->state = LOST_IN_BURST_PERIOD;
+			return true;
+		} else if (clg->a1 + clg->a4 < rnd) {
+			clg->state = TX_IN_GAP_PERIOD;
+		}
+
+		break;
+	case TX_IN_BURST_PERIOD:
+		if (rnd < clg->a5) {
+			clg->state = LOST_IN_BURST_PERIOD;
+			return true;
+		} else {
+			clg->state = TX_IN_BURST_PERIOD;
+		}
+
+		break;
+	case LOST_IN_BURST_PERIOD:
+		if (rnd < clg->a3)
+			clg->state = TX_IN_BURST_PERIOD;
+		else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
+			clg->state = TX_IN_GAP_PERIOD;
+		} else if (clg->a2 + clg->a3 < rnd) {
+			clg->state = LOST_IN_BURST_PERIOD;
+			return true;
+		}
+		break;
+	case LOST_IN_GAP_PERIOD:
+		clg->state = TX_IN_GAP_PERIOD;
+		break;
+	}
+
+	return false;
+}
+
+/* loss_gilb_ell - Gilbert-Elliot model loss generator
+ * Generates losses according to the Gilbert-Elliot loss model or
+ * its special cases  (Gilbert or Simple Gilbert)
+ *
+ * Makes a comparison between random number and the transition
+ * probabilities outgoing from the current state, then decides the
+ * next state. A second random number is extracted and the comparison
+ * with the loss probability of the current state decides if the next
+ * packet will be transmitted or lost.
+ */
+static bool loss_gilb_ell(struct netem_sched_data *q)
+{
+	struct clgstate *clg = &q->clg;
+	struct rnd_state *s = &q->prng.prng_state;
+
+	switch (clg->state) {
+	case GOOD_STATE:
+		if (prandom_u32_state(s) < clg->a1)
+			clg->state = BAD_STATE;
+		if (prandom_u32_state(s) < clg->a4)
+			return true;
+		break;
+	case BAD_STATE:
+		if (prandom_u32_state(s) < clg->a2)
+			clg->state = GOOD_STATE;
+		if (prandom_u32_state(s) > clg->a3)
+			return true;
+	}
+
+	return false;
+}
+
+static bool loss_event(struct netem_sched_data *q)
+{
+	switch (q->loss_model) {
+	case CLG_RANDOM:
+		/* Random packet drop 0 => none, ~0 => all */
+		return q->loss && q->loss >= get_crandom(&q->loss_cor, &q->prng);
+
+	case CLG_4_STATES:
+		/* 4state loss model algorithm (used also for GI model)
+		* Extracts a value from the markov 4 state loss generator,
+		* if it is 1 drops a packet and if needed writes the event in
+		* the kernel logs
+		*/
+		return loss_4state(q);
+
+	case CLG_GILB_ELL:
+		/* Gilbert-Elliot loss model algorithm
+		* Extracts a value from the Gilbert-Elliot loss generator,
+		* if it is 1 drops a packet and if needed writes the event in
+		* the kernel logs
+		*/
+		return loss_gilb_ell(q);
+	}
+
+	return false;	/* not reached */
+}
+
+
+/* tabledist - return a pseudo-randomly distributed value with mean mu and
+ * std deviation sigma.  Uses table lookup to approximate the desired
+ * distribution, and a uniformly-distributed pseudo-random source.
+ */
+static s64 tabledist(s64 mu, s32 sigma,
+		     struct crndstate *state,
+		     struct prng *prng,
+		     const struct disttable *dist)
+{
+	s64 x;
+	long t;
+	u32 rnd;
+
+	if (sigma == 0)
+		return mu;
+
+	rnd = get_crandom(state, prng);
+
+	/* default uniform distribution */
+	if (dist == NULL)
+		return ((rnd % (2 * (u32)sigma)) + mu) - sigma;
+
+	t = dist->table[rnd % dist->size];
+	x = (sigma % NETEM_DIST_SCALE) * t;
+	if (x >= 0)
+		x += NETEM_DIST_SCALE/2;
+	else
+		x -= NETEM_DIST_SCALE/2;
+
+	return  x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
+}
+
+static u64 packet_time_ns(u64 len, const struct netem_sched_data *q)
+{
+	len += q->packet_overhead;
+
+	if (q->cell_size) {
+		u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
+
+		if (len > cells * q->cell_size)	/* extra cell needed for remainder */
+			cells++;
+		len = cells * (q->cell_size + q->cell_overhead);
+	}
+
+	return div64_u64(len * NSEC_PER_SEC, q->rate);
+}
+
+static void tfifo_reset(struct Qdisc *sch)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+	struct rb_node *p = rb_first(&q->t_root);
+
+	while (p) {
+		struct sk_buff *skb = rb_to_skb(p);
+
+		p = rb_next(p);
+		rb_erase(&skb->rbnode, &q->t_root);
+		rtnl_kfree_skbs(skb, skb);
+	}
+
+	rtnl_kfree_skbs(q->t_head, q->t_tail);
+	q->t_head = NULL;
+	q->t_tail = NULL;
+}
+
+static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+	u64 tnext = netem_skb_cb(nskb)->time_to_send;
+
+	if (!q->t_tail || tnext >= netem_skb_cb(q->t_tail)->time_to_send) {
+		if (q->t_tail)
+			q->t_tail->next = nskb;
+		else
+			q->t_head = nskb;
+		q->t_tail = nskb;
+	} else {
+		struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
+
+		while (*p) {
+			struct sk_buff *skb;
+
+			parent = *p;
+			skb = rb_to_skb(parent);
+			if (tnext >= netem_skb_cb(skb)->time_to_send)
+				p = &parent->rb_right;
+			else
+				p = &parent->rb_left;
+		}
+		rb_link_node(&nskb->rbnode, parent, p);
+		rb_insert_color(&nskb->rbnode, &q->t_root);
+	}
+	sch->q.qlen++;
+}
+
+/* netem can't properly corrupt a megapacket (like we get from GSO), so instead
+ * when we statistically choose to corrupt one, we instead segment it, returning
+ * the first packet to be corrupted, and re-enqueue the remaining frames
+ */
+static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
+				     struct sk_buff **to_free)
+{
+	struct sk_buff *segs;
+	netdev_features_t features = netif_skb_features(skb);
+
+	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
+
+	if (IS_ERR_OR_NULL(segs)) {
+		qdisc_drop(skb, sch, to_free);
+		return NULL;
+	}
+	consume_skb(skb);
+	return segs;
+}
+
+/*
+ * Insert one skb into qdisc.
+ * Note: parent depends on return value to account for queue length.
+ * 	NET_XMIT_DROP: queue length didn't change.
+ *      NET_XMIT_SUCCESS: one skb was queued.
+ */
+static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+			 struct sk_buff **to_free)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+	/* We don't fill cb now as skb_unshare() may invalidate it */
+	struct netem_skb_cb *cb;
+	struct sk_buff *skb2;
+	struct sk_buff *segs = NULL;
+	unsigned int prev_len = qdisc_pkt_len(skb);
+	int count = 1;
+	int rc = NET_XMIT_SUCCESS;
+	int rc_drop = NET_XMIT_DROP;
+
+	/* Do not fool qdisc_drop_all() */
+	skb->prev = NULL;
+
+	/* Random duplication */
+	if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor, &q->prng))
+		++count;
+
+	/* Drop packet? */
+	if (loss_event(q)) {
+		if (q->ecn && INET_ECN_set_ce(skb))
+			qdisc_qstats_drop(sch); /* mark packet */
+		else
+			--count;
+	}
+	if (count == 0) {
+		qdisc_qstats_drop(sch);
+		__qdisc_drop(skb, to_free);
+		return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
+	}
+
+	/* If a delay is expected, orphan the skb. (orphaning usually takes
+	 * place at TX completion time, so _before_ the link transit delay)
+	 */
+	if (q->latency || q->jitter || q->rate)
+		skb_orphan_partial(skb);
+
+	/*
+	 * If we need to duplicate packet, then re-insert at top of the
+	 * qdisc tree, since parent queuer expects that only one
+	 * skb will be queued.
+	 */
+	if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
+		struct Qdisc *rootq = qdisc_root_bh(sch);
+		u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
+
+		q->duplicate = 0;
+		rootq->enqueue(skb2, rootq, to_free);
+		q->duplicate = dupsave;
+		rc_drop = NET_XMIT_SUCCESS;
+	}
+
+	/*
+	 * Randomized packet corruption.
+	 * Make copy if needed since we are modifying
+	 * If packet is going to be hardware checksummed, then
+	 * do it now in software before we mangle it.
+	 */
+	if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor, &q->prng)) {
+		if (skb_is_gso(skb)) {
+			skb = netem_segment(skb, sch, to_free);
+			if (!skb)
+				return rc_drop;
+			segs = skb->next;
+			skb_mark_not_on_list(skb);
+			qdisc_skb_cb(skb)->pkt_len = skb->len;
+		}
+
+		skb = skb_unshare(skb, GFP_ATOMIC);
+		if (unlikely(!skb)) {
+			qdisc_qstats_drop(sch);
+			goto finish_segs;
+		}
+		if (skb->ip_summed == CHECKSUM_PARTIAL &&
+		    skb_checksum_help(skb)) {
+			qdisc_drop(skb, sch, to_free);
+			skb = NULL;
+			goto finish_segs;
+		}
+
+		skb->data[get_random_u32_below(skb_headlen(skb))] ^=
+			1<<get_random_u32_below(8);
+	}
+
+	if (unlikely(sch->q.qlen >= sch->limit)) {
+		/* re-link segs, so that qdisc_drop_all() frees them all */
+		skb->next = segs;
+		qdisc_drop_all(skb, sch, to_free);
+		return rc_drop;
+	}
+
+	qdisc_qstats_backlog_inc(sch, skb);
+
+	cb = netem_skb_cb(skb);
+	if (q->gap == 0 ||		/* not doing reordering */
+	    q->counter < q->gap - 1 ||	/* inside last reordering gap */
+	    q->reorder < get_crandom(&q->reorder_cor, &q->prng)) {
+		u64 now;
+		s64 delay;
+
+		delay = tabledist(q->latency, q->jitter,
+				  &q->delay_cor, &q->prng, q->delay_dist);
+
+		now = ktime_get_ns();
+
+		if (q->rate) {
+			struct netem_skb_cb *last = NULL;
+
+			if (sch->q.tail)
+				last = netem_skb_cb(sch->q.tail);
+			if (q->t_root.rb_node) {
+				struct sk_buff *t_skb;
+				struct netem_skb_cb *t_last;
+
+				t_skb = skb_rb_last(&q->t_root);
+				t_last = netem_skb_cb(t_skb);
+				if (!last ||
+				    t_last->time_to_send > last->time_to_send)
+					last = t_last;
+			}
+			if (q->t_tail) {
+				struct netem_skb_cb *t_last =
+					netem_skb_cb(q->t_tail);
+
+				if (!last ||
+				    t_last->time_to_send > last->time_to_send)
+					last = t_last;
+			}
+
+			if (last) {
+				/*
+				 * Last packet in queue is reference point (now),
+				 * calculate this time bonus and subtract
+				 * from delay.
+				 */
+				delay -= last->time_to_send - now;
+				delay = max_t(s64, 0, delay);
+				now = last->time_to_send;
+			}
+
+			delay += packet_time_ns(qdisc_pkt_len(skb), q);
+		}
+
+		cb->time_to_send = now + delay;
+		++q->counter;
+		tfifo_enqueue(skb, sch);
+	} else {
+		/*
+		 * Do re-ordering by putting one out of N packets at the front
+		 * of the queue.
+		 */
+		cb->time_to_send = ktime_get_ns();
+		q->counter = 0;
+
+		__qdisc_enqueue_head(skb, &sch->q);
+		sch->qstats.requeues++;
+	}
+
+finish_segs:
+	if (segs) {
+		unsigned int len, last_len;
+		int nb;
+
+		len = skb ? skb->len : 0;
+		nb = skb ? 1 : 0;
+
+		while (segs) {
+			skb2 = segs->next;
+			skb_mark_not_on_list(segs);
+			qdisc_skb_cb(segs)->pkt_len = segs->len;
+			last_len = segs->len;
+			rc = qdisc_enqueue(segs, sch, to_free);
+			if (rc != NET_XMIT_SUCCESS) {
+				if (net_xmit_drop_count(rc))
+					qdisc_qstats_drop(sch);
+			} else {
+				nb++;
+				len += last_len;
+			}
+			segs = skb2;
+		}
+		/* Parent qdiscs accounted for 1 skb of size @prev_len */
+		qdisc_tree_reduce_backlog(sch, -(nb - 1), -(len - prev_len));
+	} else if (!skb) {
+		return NET_XMIT_DROP;
+	}
+	return NET_XMIT_SUCCESS;
+}
+
+/* Delay the next round with a new future slot with a
+ * correct number of bytes and packets.
+ */
+
+static void get_slot_next(struct netem_sched_data *q, u64 now)
+{
+	s64 next_delay;
+
+	if (!q->slot_dist)
+		next_delay = q->slot_config.min_delay +
+				(get_random_u32() *
+				 (q->slot_config.max_delay -
+				  q->slot_config.min_delay) >> 32);
+	else
+		next_delay = tabledist(q->slot_config.dist_delay,
+				       (s32)(q->slot_config.dist_jitter),
+				       NULL, &q->prng, q->slot_dist);
+
+	q->slot.slot_next = now + next_delay;
+	q->slot.packets_left = q->slot_config.max_packets;
+	q->slot.bytes_left = q->slot_config.max_bytes;
+}
+
+static struct sk_buff *netem_peek(struct netem_sched_data *q)
+{
+	struct sk_buff *skb = skb_rb_first(&q->t_root);
+	u64 t1, t2;
+
+	if (!skb)
+		return q->t_head;
+	if (!q->t_head)
+		return skb;
+
+	t1 = netem_skb_cb(skb)->time_to_send;
+	t2 = netem_skb_cb(q->t_head)->time_to_send;
+	if (t1 < t2)
+		return skb;
+	return q->t_head;
+}
+
+static void netem_erase_head(struct netem_sched_data *q, struct sk_buff *skb)
+{
+	if (skb == q->t_head) {
+		q->t_head = skb->next;
+		if (!q->t_head)
+			q->t_tail = NULL;
+	} else {
+		rb_erase(&skb->rbnode, &q->t_root);
+	}
+}
+
+static struct sk_buff *netem_dequeue(struct Qdisc *sch)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+	struct sk_buff *skb;
+
+tfifo_dequeue:
+	skb = __qdisc_dequeue_head(&sch->q);
+	if (skb) {
+		qdisc_qstats_backlog_dec(sch, skb);
+deliver:
+		qdisc_bstats_update(sch, skb);
+		return skb;
+	}
+	skb = netem_peek(q);
+	if (skb) {
+		u64 time_to_send;
+		u64 now = ktime_get_ns();
+
+		/* if more time remaining? */
+		time_to_send = netem_skb_cb(skb)->time_to_send;
+		if (q->slot.slot_next && q->slot.slot_next < time_to_send)
+			get_slot_next(q, now);
+
+		if (time_to_send <= now && q->slot.slot_next <= now) {
+			netem_erase_head(q, skb);
+			sch->q.qlen--;
+			qdisc_qstats_backlog_dec(sch, skb);
+			skb->next = NULL;
+			skb->prev = NULL;
+			/* skb->dev shares skb->rbnode area,
+			 * we need to restore its value.
+			 */
+			skb->dev = qdisc_dev(sch);
+
+			if (q->slot.slot_next) {
+				q->slot.packets_left--;
+				q->slot.bytes_left -= qdisc_pkt_len(skb);
+				if (q->slot.packets_left <= 0 ||
+				    q->slot.bytes_left <= 0)
+					get_slot_next(q, now);
+			}
+
+			if (q->qdisc) {
+				unsigned int pkt_len = qdisc_pkt_len(skb);
+				struct sk_buff *to_free = NULL;
+				int err;
+
+				err = qdisc_enqueue(skb, q->qdisc, &to_free);
+				kfree_skb_list(to_free);
+				if (err != NET_XMIT_SUCCESS &&
+				    net_xmit_drop_count(err)) {
+					qdisc_qstats_drop(sch);
+					qdisc_tree_reduce_backlog(sch, 1,
+								  pkt_len);
+				}
+				goto tfifo_dequeue;
+			}
+			goto deliver;
+		}
+
+		if (q->qdisc) {
+			skb = q->qdisc->ops->dequeue(q->qdisc);
+			if (skb)
+				goto deliver;
+		}
+
+		qdisc_watchdog_schedule_ns(&q->watchdog,
+					   max(time_to_send,
+					       q->slot.slot_next));
+	}
+
+	if (q->qdisc) {
+		skb = q->qdisc->ops->dequeue(q->qdisc);
+		if (skb)
+			goto deliver;
+	}
+	return NULL;
+}
+
+static void netem_reset(struct Qdisc *sch)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+
+	qdisc_reset_queue(sch);
+	tfifo_reset(sch);
+	if (q->qdisc)
+		qdisc_reset(q->qdisc);
+	qdisc_watchdog_cancel(&q->watchdog);
+}
+
+static void dist_free(struct disttable *d)
+{
+	kvfree(d);
+}
+
+/*
+ * Distribution data is a variable size payload containing
+ * signed 16 bit values.
+ */
+
+static int get_dist_table(struct disttable **tbl, const struct nlattr *attr)
+{
+	size_t n = nla_len(attr)/sizeof(__s16);
+	const __s16 *data = nla_data(attr);
+	struct disttable *d;
+	int i;
+
+	if (!n || n > NETEM_DIST_MAX)
+		return -EINVAL;
+
+	d = kvmalloc(struct_size(d, table, n), GFP_KERNEL);
+	if (!d)
+		return -ENOMEM;
+
+	d->size = n;
+	for (i = 0; i < n; i++)
+		d->table[i] = data[i];
+
+	*tbl = d;
+	return 0;
+}
+
+static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
+{
+	const struct tc_netem_slot *c = nla_data(attr);
+
+	q->slot_config = *c;
+	if (q->slot_config.max_packets == 0)
+		q->slot_config.max_packets = INT_MAX;
+	if (q->slot_config.max_bytes == 0)
+		q->slot_config.max_bytes = INT_MAX;
+
+	/* capping dist_jitter to the range acceptable by tabledist() */
+	q->slot_config.dist_jitter = min_t(__s64, INT_MAX, abs(q->slot_config.dist_jitter));
+
+	q->slot.packets_left = q->slot_config.max_packets;
+	q->slot.bytes_left = q->slot_config.max_bytes;
+	if (q->slot_config.min_delay | q->slot_config.max_delay |
+	    q->slot_config.dist_jitter)
+		q->slot.slot_next = ktime_get_ns();
+	else
+		q->slot.slot_next = 0;
+}
+
+static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
+{
+	const struct tc_netem_corr *c = nla_data(attr);
+
+	init_crandom(&q->delay_cor, c->delay_corr);
+	init_crandom(&q->loss_cor, c->loss_corr);
+	init_crandom(&q->dup_cor, c->dup_corr);
+}
+
+static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
+{
+	const struct tc_netem_reorder *r = nla_data(attr);
+
+	q->reorder = r->probability;
+	init_crandom(&q->reorder_cor, r->correlation);
+}
+
+static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
+{
+	const struct tc_netem_corrupt *r = nla_data(attr);
+
+	q->corrupt = r->probability;
+	init_crandom(&q->corrupt_cor, r->correlation);
+}
+
+static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
+{
+	const struct tc_netem_rate *r = nla_data(attr);
+
+	q->rate = r->rate;
+	q->packet_overhead = r->packet_overhead;
+	q->cell_size = r->cell_size;
+	q->cell_overhead = r->cell_overhead;
+	if (q->cell_size)
+		q->cell_size_reciprocal = reciprocal_value(q->cell_size);
+	else
+		q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
+}
+
+static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
+{
+	const struct nlattr *la;
+	int rem;
+
+	nla_for_each_nested(la, attr, rem) {
+		u16 type = nla_type(la);
+
+		switch (type) {
+		case NETEM_LOSS_GI: {
+			const struct tc_netem_gimodel *gi = nla_data(la);
+
+			if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
+				pr_info("netem: incorrect gi model size\n");
+				return -EINVAL;
+			}
+
+			q->loss_model = CLG_4_STATES;
+
+			q->clg.state = TX_IN_GAP_PERIOD;
+			q->clg.a1 = gi->p13;
+			q->clg.a2 = gi->p31;
+			q->clg.a3 = gi->p32;
+			q->clg.a4 = gi->p14;
+			q->clg.a5 = gi->p23;
+			break;
+		}
+
+		case NETEM_LOSS_GE: {
+			const struct tc_netem_gemodel *ge = nla_data(la);
+
+			if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
+				pr_info("netem: incorrect ge model size\n");
+				return -EINVAL;
+			}
+
+			q->loss_model = CLG_GILB_ELL;
+			q->clg.state = GOOD_STATE;
+			q->clg.a1 = ge->p;
+			q->clg.a2 = ge->r;
+			q->clg.a3 = ge->h;
+			q->clg.a4 = ge->k1;
+			break;
+		}
+
+		default:
+			pr_info("netem: unknown loss type %u\n", type);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
+	[TCA_NETEM_CORR]	= { .len = sizeof(struct tc_netem_corr) },
+	[TCA_NETEM_REORDER]	= { .len = sizeof(struct tc_netem_reorder) },
+	[TCA_NETEM_CORRUPT]	= { .len = sizeof(struct tc_netem_corrupt) },
+	[TCA_NETEM_RATE]	= { .len = sizeof(struct tc_netem_rate) },
+	[TCA_NETEM_LOSS]	= { .type = NLA_NESTED },
+	[TCA_NETEM_ECN]		= { .type = NLA_U32 },
+	[TCA_NETEM_RATE64]	= { .type = NLA_U64 },
+	[TCA_NETEM_LATENCY64]	= { .type = NLA_S64 },
+	[TCA_NETEM_JITTER64]	= { .type = NLA_S64 },
+	[TCA_NETEM_SLOT]	= { .len = sizeof(struct tc_netem_slot) },
+	[TCA_NETEM_PRNG_SEED]	= { .type = NLA_U64 },
+};
+
+static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
+		      const struct nla_policy *policy, int len)
+{
+	int nested_len = nla_len(nla) - NLA_ALIGN(len);
+
+	if (nested_len < 0) {
+		pr_info("netem: invalid attributes len %d\n", nested_len);
+		return -EINVAL;
+	}
+
+	if (nested_len >= nla_attr_size(0))
+		return nla_parse_deprecated(tb, maxtype,
+					    nla_data(nla) + NLA_ALIGN(len),
+					    nested_len, policy, NULL);
+
+	memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
+	return 0;
+}
+
+/* Parse netlink message to set options */
+static int netem_change(struct Qdisc *sch, struct nlattr *opt,
+			struct netlink_ext_ack *extack)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+	struct nlattr *tb[TCA_NETEM_MAX + 1];
+	struct disttable *delay_dist = NULL;
+	struct disttable *slot_dist = NULL;
+	struct tc_netem_qopt *qopt;
+	struct clgstate old_clg;
+	int old_loss_model = CLG_RANDOM;
+	int ret;
+
+	qopt = nla_data(opt);
+	ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
+	if (ret < 0)
+		return ret;
+
+	if (tb[TCA_NETEM_DELAY_DIST]) {
+		ret = get_dist_table(&delay_dist, tb[TCA_NETEM_DELAY_DIST]);
+		if (ret)
+			goto table_free;
+	}
+
+	if (tb[TCA_NETEM_SLOT_DIST]) {
+		ret = get_dist_table(&slot_dist, tb[TCA_NETEM_SLOT_DIST]);
+		if (ret)
+			goto table_free;
+	}
+
+	sch_tree_lock(sch);
+	/* backup q->clg and q->loss_model */
+	old_clg = q->clg;
+	old_loss_model = q->loss_model;
+
+	if (tb[TCA_NETEM_LOSS]) {
+		ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
+		if (ret) {
+			q->loss_model = old_loss_model;
+			q->clg = old_clg;
+			goto unlock;
+		}
+	} else {
+		q->loss_model = CLG_RANDOM;
+	}
+
+	if (delay_dist)
+		swap(q->delay_dist, delay_dist);
+	if (slot_dist)
+		swap(q->slot_dist, slot_dist);
+	sch->limit = qopt->limit;
+
+	q->latency = PSCHED_TICKS2NS(qopt->latency);
+	q->jitter = PSCHED_TICKS2NS(qopt->jitter);
+	q->limit = qopt->limit;
+	q->gap = qopt->gap;
+	q->counter = 0;
+	q->loss = qopt->loss;
+	q->duplicate = qopt->duplicate;
+
+	/* for compatibility with earlier versions.
+	 * if gap is set, need to assume 100% probability
+	 */
+	if (q->gap)
+		q->reorder = ~0;
+
+	if (tb[TCA_NETEM_CORR])
+		get_correlation(q, tb[TCA_NETEM_CORR]);
+
+	if (tb[TCA_NETEM_REORDER])
+		get_reorder(q, tb[TCA_NETEM_REORDER]);
+
+	if (tb[TCA_NETEM_CORRUPT])
+		get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
+
+	if (tb[TCA_NETEM_RATE])
+		get_rate(q, tb[TCA_NETEM_RATE]);
+
+	if (tb[TCA_NETEM_RATE64])
+		q->rate = max_t(u64, q->rate,
+				nla_get_u64(tb[TCA_NETEM_RATE64]));
+
+	if (tb[TCA_NETEM_LATENCY64])
+		q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
+
+	if (tb[TCA_NETEM_JITTER64])
+		q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
+
+	if (tb[TCA_NETEM_ECN])
+		q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
+
+	if (tb[TCA_NETEM_SLOT])
+		get_slot(q, tb[TCA_NETEM_SLOT]);
+
+	/* capping jitter to the range acceptable by tabledist() */
+	q->jitter = min_t(s64, abs(q->jitter), INT_MAX);
+
+	if (tb[TCA_NETEM_PRNG_SEED])
+		q->prng.seed = nla_get_u64(tb[TCA_NETEM_PRNG_SEED]);
+	else
+		q->prng.seed = get_random_u64();
+	prandom_seed_state(&q->prng.prng_state, q->prng.seed);
+
+unlock:
+	sch_tree_unlock(sch);
+
+table_free:
+	dist_free(delay_dist);
+	dist_free(slot_dist);
+	return ret;
+}
+
+static int netem_init(struct Qdisc *sch, struct nlattr *opt,
+		      struct netlink_ext_ack *extack)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+	int ret;
+
+	qdisc_watchdog_init(&q->watchdog, sch);
+
+	if (!opt)
+		return -EINVAL;
+
+	q->loss_model = CLG_RANDOM;
+	ret = netem_change(sch, opt, extack);
+	if (ret)
+		pr_info("netem: change failed\n");
+	return ret;
+}
+
+static void netem_destroy(struct Qdisc *sch)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+
+	qdisc_watchdog_cancel(&q->watchdog);
+	if (q->qdisc)
+		qdisc_put(q->qdisc);
+	dist_free(q->delay_dist);
+	dist_free(q->slot_dist);
+}
+
+static int dump_loss_model(const struct netem_sched_data *q,
+			   struct sk_buff *skb)
+{
+	struct nlattr *nest;
+
+	nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS);
+	if (nest == NULL)
+		goto nla_put_failure;
+
+	switch (q->loss_model) {
+	case CLG_RANDOM:
+		/* legacy loss model */
+		nla_nest_cancel(skb, nest);
+		return 0;	/* no data */
+
+	case CLG_4_STATES: {
+		struct tc_netem_gimodel gi = {
+			.p13 = q->clg.a1,
+			.p31 = q->clg.a2,
+			.p32 = q->clg.a3,
+			.p14 = q->clg.a4,
+			.p23 = q->clg.a5,
+		};
+
+		if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
+			goto nla_put_failure;
+		break;
+	}
+	case CLG_GILB_ELL: {
+		struct tc_netem_gemodel ge = {
+			.p = q->clg.a1,
+			.r = q->clg.a2,
+			.h = q->clg.a3,
+			.k1 = q->clg.a4,
+		};
+
+		if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
+			goto nla_put_failure;
+		break;
+	}
+	}
+
+	nla_nest_end(skb, nest);
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -1;
+}
+
+static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+	const struct netem_sched_data *q = qdisc_priv(sch);
+	struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
+	struct tc_netem_qopt qopt;
+	struct tc_netem_corr cor;
+	struct tc_netem_reorder reorder;
+	struct tc_netem_corrupt corrupt;
+	struct tc_netem_rate rate;
+	struct tc_netem_slot slot;
+
+	qopt.latency = min_t(psched_time_t, PSCHED_NS2TICKS(q->latency),
+			     UINT_MAX);
+	qopt.jitter = min_t(psched_time_t, PSCHED_NS2TICKS(q->jitter),
+			    UINT_MAX);
+	qopt.limit = q->limit;
+	qopt.loss = q->loss;
+	qopt.gap = q->gap;
+	qopt.duplicate = q->duplicate;
+	if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
+		goto nla_put_failure;
+
+	if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
+		goto nla_put_failure;
+
+	if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
+		goto nla_put_failure;
+
+	cor.delay_corr = q->delay_cor.rho;
+	cor.loss_corr = q->loss_cor.rho;
+	cor.dup_corr = q->dup_cor.rho;
+	if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
+		goto nla_put_failure;
+
+	reorder.probability = q->reorder;
+	reorder.correlation = q->reorder_cor.rho;
+	if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
+		goto nla_put_failure;
+
+	corrupt.probability = q->corrupt;
+	corrupt.correlation = q->corrupt_cor.rho;
+	if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
+		goto nla_put_failure;
+
+	if (q->rate >= (1ULL << 32)) {
+		if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
+				      TCA_NETEM_PAD))
+			goto nla_put_failure;
+		rate.rate = ~0U;
+	} else {
+		rate.rate = q->rate;
+	}
+	rate.packet_overhead = q->packet_overhead;
+	rate.cell_size = q->cell_size;
+	rate.cell_overhead = q->cell_overhead;
+	if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
+		goto nla_put_failure;
+
+	if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
+		goto nla_put_failure;
+
+	if (dump_loss_model(q, skb) != 0)
+		goto nla_put_failure;
+
+	if (q->slot_config.min_delay | q->slot_config.max_delay |
+	    q->slot_config.dist_jitter) {
+		slot = q->slot_config;
+		if (slot.max_packets == INT_MAX)
+			slot.max_packets = 0;
+		if (slot.max_bytes == INT_MAX)
+			slot.max_bytes = 0;
+		if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
+			goto nla_put_failure;
+	}
+
+	if (nla_put_u64_64bit(skb, TCA_NETEM_PRNG_SEED, q->prng.seed,
+			      TCA_NETEM_PAD))
+		goto nla_put_failure;
+
+	return nla_nest_end(skb, nla);
+
+nla_put_failure:
+	nlmsg_trim(skb, nla);
+	return -1;
+}
+
+static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
+			  struct sk_buff *skb, struct tcmsg *tcm)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+
+	if (cl != 1 || !q->qdisc) 	/* only one class */
+		return -ENOENT;
+
+	tcm->tcm_handle |= TC_H_MIN(1);
+	tcm->tcm_info = q->qdisc->handle;
+
+	return 0;
+}
+
+static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+		     struct Qdisc **old, struct netlink_ext_ack *extack)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+
+	*old = qdisc_replace(sch, new, &q->qdisc);
+	return 0;
+}
+
+static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+	return q->qdisc;
+}
+
+static unsigned long netem_find(struct Qdisc *sch, u32 classid)
+{
+	return 1;
+}
+
+static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
+{
+	if (!walker->stop) {
+		if (!tc_qdisc_stats_dump(sch, 1, walker))
+			return;
+	}
+}
+
+static const struct Qdisc_class_ops netem_class_ops = {
+	.graft		=	netem_graft,
+	.leaf		=	netem_leaf,
+	.find		=	netem_find,
+	.walk		=	netem_walk,
+	.dump		=	netem_dump_class,
+};
+
+static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
+	.id		=	"netem",
+	.cl_ops		=	&netem_class_ops,
+	.priv_size	=	sizeof(struct netem_sched_data),
+	.enqueue	=	netem_enqueue,
+	.dequeue	=	netem_dequeue,
+	.peek		=	qdisc_peek_dequeued,
+	.init		=	netem_init,
+	.reset		=	netem_reset,
+	.destroy	=	netem_destroy,
+	.change		=	netem_change,
+	.dump		=	netem_dump,
+	.owner		=	THIS_MODULE,
+};
+
+
+static int __init netem_module_init(void)
+{
+	pr_info("netem: version " VERSION "\n");
+	return register_qdisc(&netem_qdisc_ops);
+}
+static void __exit netem_module_exit(void)
+{
+	unregister_qdisc(&netem_qdisc_ops);
+}
+module_init(netem_module_init)
+module_exit(netem_module_exit)
+MODULE_LICENSE("GPL");