net classifier: deinline bind/unbind functions

@@ -40,15 +40,21 @@ cls_set_class(struct tcf_proto *tp, unsi
 	return old_cl;
 }
 
-static inline void
+static inline int
 tcf_bind_filter(struct tcf_proto *tp, struct tcf_result *r, unsigned long base)
 {
+	const struct Qdisc_class_ops *cops = tp->q->ops->cl_ops;
 	unsigned long cl;
 
-	cl = tp->q->ops->cl_ops->bind_tcf(tp->q, base, r->classid);
+	if (!cops->bind_tcf)
+		return -EINVAL;
+
+	cl = cops->bind_tcf(tp->q, base, r->classid);
 	cl = cls_set_class(tp, &r->class, cl);
 	if (cl)
-		tp->q->ops->cl_ops->unbind_tcf(tp->q, cl);
+		cops->unbind_tcf(tp->q, cl);
+
+	return 0;
 }
 
 static inline void

@@ -153,7 +153,9 @@ static inline int basic_set_parms(struct
 
 	if (tb[TCA_BASIC_CLASSID]) {
 		f->res.classid = nla_get_u32(tb[TCA_BASIC_CLASSID]);
-		tcf_bind_filter(tp, &f->res, base);
+		err = tcf_bind_filter(tp, &f->res, base);
+		if (err)
+			goto errout;
 	}
 
 	tcf_exts_change(tp, &f->exts, &e);

@@ -206,10 +206,11 @@ fw_change_attrs(struct tcf_proto *tp, st
 	if (err < 0)
 		return err;
 
-	err = -EINVAL;
 	if (tb[TCA_FW_CLASSID]) {
 		f->res.classid = nla_get_u32(tb[TCA_FW_CLASSID]);
-		tcf_bind_filter(tp, &f->res, base);
+		err = tcf_bind_filter(tp, &f->res, base);
+		if (err)
+			goto errout;
 	}
 
 #ifdef CONFIG_NET_CLS_IND

@@ -220,6 +221,7 @@ fw_change_attrs(struct tcf_proto *tp, st
 	}
 #endif /* CONFIG_NET_CLS_IND */
 
+	err = -EINVAL;
 	if (tb[TCA_FW_MASK]) {
 		mask = nla_get_u32(tb[TCA_FW_MASK]);
 		if (mask != head->mask)

@@ -412,7 +412,9 @@ static int route4_set_parms(struct tcf_p
 
 	if (tb[TCA_ROUTE4_CLASSID]) {
 		f->res.classid = nla_get_u32(tb[TCA_ROUTE4_CLASSID]);
-		tcf_bind_filter(tp, &f->res, base);
+		err = tcf_bind_filter(tp, &f->res, base);
+		if (err)
+			goto errout;
 	}
 
 	tcf_exts_change(tp, &f->exts, &e);

@@ -295,7 +295,9 @@ tcindex_set_parms(struct tcf_proto *tp, 
 
 	if (tb[TCA_TCINDEX_CLASSID]) {
 		cr.res.classid = nla_get_u32(tb[TCA_TCINDEX_CLASSID]);
-		tcf_bind_filter(tp, &cr.res, base);
+		err = tcf_bind_filter(tp, &cr.res, base);
+		if (err)
+			goto errout;
 	}
 
 	tcf_exts_change(tp, &cr.exts, &e);

@@ -528,7 +528,9 @@ static int u32_set_parms(struct tcf_prot
 	}
 	if (tb[TCA_U32_CLASSID]) {
 		n->res.classid = nla_get_u32(tb[TCA_U32_CLASSID]);
-		tcf_bind_filter(tp, &n->res, base);
+		err = tcf_bind_filter(tp, &n->res, base);
+		if (err)
+			goto errout;
 	}
 
 #ifdef CONFIG_NET_CLS_IND

@@ -502,6 +502,10 @@ static unsigned long sfq_get(struct Qdis
 	return 0;
 }
 
+static void sfq_put(struct Qdisc *q, unsigned long cl)
+{
+}
+
 static struct tcf_proto **sfq_find_tcf(struct Qdisc *sch, unsigned long cl)
 {
 	struct sfq_sched_data *q = qdisc_priv(sch);

@@ -511,6 +515,12 @@ static struct tcf_proto **sfq_find_tcf(s
 	return &q->filter_list;
 }
 
+static unsigned long sfq_bind_tcf(struct Qdisc *sch, unsigned long parent,
+				  u32 cl)
+{
+	return 0;
+}
+
 static int sfq_dump_class(struct Qdisc *sch, unsigned long cl,
 			  struct sk_buff *skb, struct tcmsg *tcm)
 {

@@ -556,6 +566,8 @@ static void sfq_walk(struct Qdisc *sch, 
 static const struct Qdisc_class_ops sfq_class_ops = {
 	.get		=	sfq_get,
 	.tcf_chain	=	sfq_find_tcf,
+	.bind_tcf	=	sfq_bind_tcf,
+	.unbind_tcf	=	sfq_put,
 	.dump		=	sfq_dump_class,
 	.dump_stats	=	sfq_dump_class_stats,

@@ -16,55 +16,9 @@ struct tcf_walker {
 
 extern int register_tcf_proto_ops(struct tcf_proto_ops *ops);
 extern int unregister_tcf_proto_ops(struct tcf_proto_ops *ops);
-
-static inline unsigned long
-__cls_set_class(unsigned long *clp, unsigned long cl)
-{
-	unsigned long old_cl;
- 
-	old_cl = *clp;
-	*clp = cl;
-	return old_cl;
-}
-
-static inline unsigned long
-cls_set_class(struct tcf_proto *tp, unsigned long *clp, 
-	unsigned long cl)
-{
-	unsigned long old_cl;
-	
-	tcf_tree_lock(tp);
-	old_cl = __cls_set_class(clp, cl);
-	tcf_tree_unlock(tp);
- 
-	return old_cl;
-}
-
-static inline int
-tcf_bind_filter(struct tcf_proto *tp, struct tcf_result *r, unsigned long base)
-{
-	const struct Qdisc_class_ops *cops = tp->q->ops->cl_ops;
-	unsigned long cl;
-
-	if (!cops->bind_tcf)
-		return -EINVAL;
-
-	cl = cops->bind_tcf(tp->q, base, r->classid);
-	cl = cls_set_class(tp, &r->class, cl);
-	if (cl)
-		cops->unbind_tcf(tp->q, cl);
-
-	return 0;
-}
-
-static inline void
-tcf_unbind_filter(struct tcf_proto *tp, struct tcf_result *r)
-{
-	unsigned long cl;
-
-	if ((cl = __cls_set_class(&r->class, 0)) != 0)
-		tp->q->ops->cl_ops->unbind_tcf(tp->q, cl);
-}
+extern int tcf_bind_filter(struct tcf_proto *tp, struct tcf_result *r,
+			   unsigned long base);
+extern void tcf_unbind_filter(struct tcf_proto *tp, struct tcf_result *r);
 
 struct tcf_exts {
 #ifdef CONFIG_NET_CLS_ACT

56 lines not on this page · raw message

@@ -135,12 +135,12 @@ next_knode:
 
 		for (i = n->sel.nkeys; i>0; i--, key++) {
 			int toff = off + key->off + (off2 & key->offmask);
-			__be32 *data, _data;
+			__be32 *data, hdata;
 
 			if (skb_headroom(skb) + toff < 0)
 				goto out;
 
-			data = skb_header_pointer(skb, toff, 4, &_data);
+			data = skb_header_pointer(skb, toff, 4, &hdata);
 			if (!data)
 				goto out;
 			if ((*data ^ key->val) & key->mask) {

@@ -188,10 +188,10 @@ check_terminal:
 		ht = n->ht_down;
 		sel = 0;
 		if (ht->divisor) {
-			__be32 *data, _data;
+			__be32 *data, hdata;
 
 			data = skb_header_pointer(skb, off + n->sel.hoff, 4,
-						  &_data);
+						  &hdata);
 			if (!data)
 				goto out;
 			sel = ht->divisor & u32_hash_fold(*data, &n->sel,

@@ -203,11 +203,11 @@ check_terminal:
 		if (n->sel.flags&(TC_U32_OFFSET|TC_U32_VAROFFSET)) {
 			off2 = n->sel.off + 3;
 			if (n->sel.flags & TC_U32_VAROFFSET) {
-				__be16 *data, _data;
+				__be16 *data, hdata;
 
 				data = skb_header_pointer(skb,
 							  off + n->sel.offoff,
-							  2, &_data);
+							  2, &hdata);
 				if (!data)
 					goto out;
 				off2 += ntohs(n->sel.offmask & *data) >>

@@ -318,7 +318,6 @@ static int get_dist_table(struct Qdisc *
 	struct netem_sched_data *q = qdisc_priv(sch);
 	unsigned long n = nla_len(attr)/sizeof(__s16);
 	const __s16 *data = nla_data(attr);
-	spinlock_t *root_lock;
 	struct disttable *d;
 	int i;
 

@@ -333,12 +332,9 @@ static int get_dist_table(struct Qdisc *
 	for (i = 0; i < n; i++)
 		d->table[i] = data[i];
 
-	root_lock = qdisc_root_sleeping_lock(sch);
-
-	spin_lock_bh(root_lock);
 	kfree(q->delay_dist);
 	q->delay_dist = d;
-	spin_unlock_bh(root_lock);
+
 	return 0;
 }
 

@@ -412,6 +408,7 @@ static int netem_change(struct Qdisc *sc
 		return ret;
 	}
 
+	sch_tree_lock(sch);
 	q->latency = qopt->latency;
 	q->jitter = qopt->jitter;
 	q->limit = qopt->limit;

@@ -432,7 +429,7 @@ static int netem_change(struct Qdisc *sc
 	if (tb[TCA_NETEM_DELAY_DIST]) {
 		ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
 		if (ret)
-			return ret;
+			goto out;
 	}
 
 	if (tb[TCA_NETEM_REORDER])

@@ -440,6 +437,8 @@ static int netem_change(struct Qdisc *sc
 
 	if (tb[TCA_NETEM_CORRUPT])
 		get_corrupt(sch, tb[TCA_NETEM_CORRUPT]);
+ out:
+	sch_tree_unlock(sch);
 
 	return 0;
 }

@@ -565,8 +565,7 @@ static void netem_destroy(struct Qdisc *
 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
 	const struct netem_sched_data *q = qdisc_priv(sch);
-	unsigned char *b = skb_tail_pointer(skb);
-	struct nlattr *nla = (struct nlattr *) b;
+	struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
 	struct tc_netem_qopt qopt;
 	struct tc_netem_corr cor;
 	struct tc_netem_reorder reorder;

@@ -593,12 +592,10 @@ static int netem_dump(struct Qdisc *sch,
 	corrupt.correlation = q->corrupt_cor.rho;
 	NLA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);
 
-	nla->nla_len = skb_tail_pointer(skb) - b;
-
-	return skb->len;
+	return nla_nest_end(skb, nla);
 
 nla_put_failure:
-	nlmsg_trim(skb, b);
+	nlmsg_trim(skb, nla);
 	return -1;
 }
 

@@ -466,6 +466,7 @@ struct tc_netem_corrupt {
 };
 
 #define NETEM_DIST_SCALE	8192
+#define NETEM_DIST_MAX		16384
 
 /* DRR */
 

@@ -321,10 +321,10 @@ static int get_dist_table(struct Qdisc *
 	struct disttable *d;
 	int i;
 
-	if (n > 65536)
+	if (n > NETEM_DIST_MAX)
 		return -EINVAL;
 
-	d = kmalloc(sizeof(*d) + n*sizeof(d->table[0]), GFP_KERNEL);
+	d = vmalloc(sizeof(*d) + n*sizeof(d->table[0]));
 	if (!d)
 		return -ENOMEM;
 

@@ -332,7 +332,7 @@ static int get_dist_table(struct Qdisc *
 	for (i = 0; i < n; i++)
 		d->table[i] = data[i];
 
-	kfree(q->delay_dist);
+	vfree(q->delay_dist);
 	q->delay_dist = d;
 
 	return 0;

@@ -559,7 +559,7 @@ static void netem_destroy(struct Qdisc *
 
 	qdisc_watchdog_cancel(&q->watchdog);
 	qdisc_destroy(q->qdisc);
-	kfree(q->delay_dist);
+	vfree(q->delay_dist);
 }
 
 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)

@@ -592,6 +592,13 @@ static int netem_dump(struct Qdisc *sch,
 	corrupt.correlation = q->corrupt_cor.rho;
 	NLA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);
 
+	/* dump table if exists and there is space available */
+	if (q->delay_dist) {
+		const struct disttable *d = q->delay_dist;
+		nla_put(skb, TCA_NETEM_DELAY_DIST,
+			d->size * sizeof(__s16), d->table);
+	}
+
 	return nla_nest_end(skb, nla);
 
 nla_put_failure:

@@ -47,6 +47,20 @@
 	 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 netem_sched_data {

@@ -73,6 +87,26 @@ struct netem_sched_data {
 		u32  size;
 		s16 table[0];
 	} *delay_dist;
+
+	enum  {
+		CLG_RANDOM,
+		CLG_4_STATES,
+		CLG_GILB_ELL,
+	} loss_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;
+
 };
 
 /* Time stamp put into socket buffer control block */

@@ -119,6 +153,122 @@ static u32 get_crandom(struct crndstate 
 	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 = net_random();
+
+	/*
+	 * Makes a comparision 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:
+	 *   1 => successfully transmitted packets within a gap period
+	 *   4 => isolated losses within a gap period
+	 *   3 => lost packets within a burst period
+	 *   2 => successfully transmitted packets within a burst period
+	 */
+	switch (clg->state) {
+	case 1:
+		if (rnd < clg->a4) {
+			clg->state = 4;
+			return true;
+		} else if (clg->a4 < rnd && rnd < clg->a1) {
+			clg->state = 3;
+			return true;
+		} else if (clg->a1 < rnd)
+			clg->state = 1;
+
+		break;
+	case 2:
+		if (rnd < clg->a5) {
+			clg->state = 3;
+			return true;
+		} else
+			clg->state = 2;
+
+		break;
+	case 3:
+		if (rnd < clg->a3)
+			clg->state = 2;
+		else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
+			clg->state = 1;
+			return true;
+		} else if (clg->a2 + clg->a3 < rnd) {
+			clg->state = 3;
+			return true;
+		}
+		break;
+	case 4:
+		clg->state = 1;
+		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 comparision 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 comparision
+ * 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;
+
+	switch (clg->state) {
+	case 1:
+		if (net_random() < clg->a1)
+			clg->state = 2;
+		if (net_random() < clg->a4)
+			return true;
+	case 2:
+		if (net_random() < clg->a2)
+			clg->state = 1;
+		if (clg->a3 > net_random())
+			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);
+
+	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.

@@ -171,8 +321,8 @@ static int netem_enqueue(struct sk_buff 
 	if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
 		++count;
 
-	/* Random packet drop 0 => none, ~0 => all */
-	if (q->loss && q->loss >= get_crandom(&q->loss_cor))
+	/* Drop packet? */
+	if (loss_event(q))
 		--count;
 
 	if (count == 0) {

@@ -370,10 +520,62 @@ static void get_corrupt(struct Qdisc *sc
 	init_crandom(&q->corrupt_cor, r->correlation);
 }
 
+static int get_loss_clg(struct Qdisc *sch, const struct nlattr *attr)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+	struct nlattr *la;
+	int rem;
+
+	nla_for_each_nested(la, attr, rem) {
+		switch(nla_type(la)) {
+		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 = 1;
+			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 gi model size\n");
+				return -EINVAL;
+			}
+
+			q->loss_model = CLG_GILB_ELL;
+			q->clg.state = 1;
+			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 element %d\n",
+				nla_type(la));
+			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_LOSS]	= { .type = NLA_NESTED },
 };
 
 static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,

@@ -441,10 +643,14 @@ static int netem_change(struct Qdisc *sc
 
 	if (tb[TCA_NETEM_CORRUPT])
 		get_corrupt(sch, tb[TCA_NETEM_CORRUPT]);
+
+	q->loss_model = CLG_RANDOM;
+	if (tb[TCA_NETEM_LOSS])
+		ret = get_loss_clg(sch, tb[TCA_NETEM_LOSS]);
  out:
 	sch_tree_unlock(sch);
 
-	return 0;
+	return ret;
 }
 
 /*

@@ -542,6 +748,7 @@ static int netem_init(struct Qdisc *sch,
 
 	qdisc_watchdog_init(&q->watchdog, sch);
 
+	q->loss_model = CLG_RANDOM;
 	q->qdisc = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
 				     ops, TC_H_MAKE(sch->handle, 1));
 	if (!q->qdisc) {

@@ -566,6 +773,52 @@ static void netem_destroy(struct Qdisc *
 	vfree(q->delay_dist);
 }
 
+static int dump_loss_model(const struct netem_sched_data *q, struct sk_buff *skb)
+{
+	struct nlattr *nest;
+
+	nest = nla_nest_start(skb, NETEM_LOSS_MAX);
+	if (nest == NULL)
+		goto nla_put_failure;
+
+	switch (q->loss_model) {
+	case CLG_RANDOM:
+		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,
+		};
+
+		NLA_PUT(skb, NETEM_LOSS_GI, sizeof(gi), &gi);
+		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,
+		};
+
+		NLA_PUT(skb, NETEM_LOSS_GE, sizeof(ge), &ge);
+		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);

@@ -603,6 +856,9 @@ static int netem_dump(struct Qdisc *sch,
 			d->size * sizeof(__s16), d->table);
 	}
 
+	if (dump_loss_model(q, skb) != 0)
+		goto nla_put_failure;
+
 	return nla_nest_end(skb, nla);
 
 nla_put_failure:

@@ -435,6 +435,7 @@ enum {
 	TCA_NETEM_DELAY_DIST,
 	TCA_NETEM_REORDER,
 	TCA_NETEM_CORRUPT,
+	TCA_NETEM_LOSS,
 	__TCA_NETEM_MAX,
 };
 

@@ -465,6 +466,30 @@ struct tc_netem_corrupt {
 	__u32	correlation;
 };
 
+enum {
+	NETEM_LOSS_GI,		/* General Intuitive - 4 state model */
+	NETEM_LOSS_GE,		/* Gilbert Elliot models */
+	__NETEM_LOSS_MAX
+};
+#define NETEM_LOSS_MAX (__NETEM_LOSS_MAX - 1)
+
+/* State transition probablities for 4 state model */
+struct tc_netem_gimodel {
+	__u32	p13;
+	__u32	p31;
+	__u32	p32;
+	__u32	p14;
+	__u32	p23;
+};
+
+/* Gilbert-Elliot models */
+struct tc_netem_gemodel {
+	__u32 p;
+	__u32 r;
+	__u32 h;
+	__u32 k1;
+};
+
 #define NETEM_DIST_SCALE	8192
 #define NETEM_DIST_MAX		16384
 

@@ -87,6 +87,10 @@ static inline struct netem_skb_cb *netem
 	return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
 }
 
+static int jitter = 1;
+module_param(jitter, int, 0);
+MODULE_PARM_DESC(jitter, "reorder packets based on delay");
+
 /* init_crandom - initialize correlated random number generator
  * Use entropy source for initial seed.
  */

@@ -531,6 +535,7 @@ static struct Qdisc_ops tfifo_qdisc_ops 
 static int netem_init(struct Qdisc *sch, struct nlattr *opt)
 {
 	struct netem_sched_data *q = qdisc_priv(sch);
+	struct Qdisc_ops *ops = jitter ? &tfifo_qdisc_ops : &pfifo_qdisc_ops;
 	int ret;
 
 	if (!opt)

@@ -539,8 +544,7 @@ static int netem_init(struct Qdisc *sch,
 	qdisc_watchdog_init(&q->watchdog, sch);
 
 	q->qdisc = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
-				     &tfifo_qdisc_ops,
-				     TC_H_MAKE(sch->handle, 1));
+				     ops, TC_H_MAKE(sch->handle, 1));
 	if (!q->qdisc) {
 		pr_debug("netem: qdisc create failed\n");
 		return -ENOMEM;