[PATCH v2 net-next 1/3] netem: convert to qdisc_watchdog_schedule_ns

[Dave Taht <dave.taht@gmail.com>]

Upgrade the internal netem scheduler to use nanoseconds rather than
ticks throughout.

Convert to and from the std "ticks" userspace api automatically,
while allowing for finer grained scheduling to take place.

Signed-off-by: Dave Taht <dave.taht@gmail.com>
---
 net/sched/sch_netem.c | 56 +++++++++++++++++++++++++--------------------------
 1 file changed, 28 insertions(+), 28 deletions(-)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index db0228a..5559ad1 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -77,8 +77,8 @@ struct netem_sched_data {
 
 	struct qdisc_watchdog watchdog;
 
-	psched_tdiff_t latency;
-	psched_tdiff_t jitter;
+	s64 latency;
+	s64 jitter;
 
 	u32 loss;
 	u32 ecn;
@@ -145,7 +145,7 @@ struct netem_sched_data {
  * we save skb->tstamp value in skb->cb[] before destroying it.
  */
 struct netem_skb_cb {
-	psched_time_t	time_to_send;
+	u64	        time_to_send;
 };
 
 static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
@@ -305,11 +305,11 @@ static bool loss_event(struct netem_sched_data *q)
  * std deviation sigma.  Uses table lookup to approximate the desired
  * distribution, and a uniformly-distributed pseudo-random source.
  */
-static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
-				struct crndstate *state,
-				const struct disttable *dist)
+static s64 tabledist(s64 mu, s64 sigma,
+		     struct crndstate *state,
+			 const struct disttable *dist)
 {
-	psched_tdiff_t x;
+	s64 x;
 	long t;
 	u32 rnd;
 
@@ -332,10 +332,10 @@ static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
 	return  x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
 }
 
-static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sched_data *q)
+static s64 packet_len_2_sched_time(unsigned int len,
+				   struct netem_sched_data *q)
 {
-	u64 ticks;
-
+	s64 offset;
 	len += q->packet_overhead;
 
 	if (q->cell_size) {
@@ -345,11 +345,9 @@ static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sche
 			cells++;
 		len = cells * (q->cell_size + q->cell_overhead);
 	}
-
-	ticks = (u64)len * NSEC_PER_SEC;
-
-	do_div(ticks, q->rate);
-	return PSCHED_NS2TICKS(ticks);
+	offset = (s64)len * NSEC_PER_SEC;
+	do_div(offset, q->rate);
+	return offset;
 }
 
 static void tfifo_reset(struct Qdisc *sch)
@@ -369,7 +367,7 @@ static void tfifo_reset(struct Qdisc *sch)
 static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
 {
 	struct netem_sched_data *q = qdisc_priv(sch);
-	psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
+	u64 tnext = netem_skb_cb(nskb)->time_to_send;
 	struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
 
 	while (*p) {
@@ -515,13 +513,13 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 	if (q->gap == 0 ||		/* not doing reordering */
 	    q->counter < q->gap - 1 ||	/* inside last reordering gap */
 	    q->reorder < get_crandom(&q->reorder_cor)) {
-		psched_time_t now;
-		psched_tdiff_t delay;
+		u64 now;
+		s64 delay;
 
 		delay = tabledist(q->latency, q->jitter,
 				  &q->delay_cor, q->delay_dist);
 
-		now = psched_get_time();
+		now = ktime_get_ns();
 
 		if (q->rate) {
 			struct netem_skb_cb *last = NULL;
@@ -547,7 +545,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 				 * from delay.
 				 */
 				delay -= last->time_to_send - now;
-				delay = max_t(psched_tdiff_t, 0, delay);
+				delay = max_t(s64, 0, delay);
 				now = last->time_to_send;
 			}
 
@@ -562,7 +560,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 		 * Do re-ordering by putting one out of N packets at the front
 		 * of the queue.
 		 */
-		cb->time_to_send = psched_get_time();
+		cb->time_to_send = ktime_get_ns();
 		q->counter = 0;
 
 		netem_enqueue_skb_head(&sch->q, skb);
@@ -609,13 +607,13 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
 	}
 	p = rb_first(&q->t_root);
 	if (p) {
-		psched_time_t time_to_send;
+		u64 time_to_send;
 
 		skb = rb_to_skb(p);
 
 		/* if more time remaining? */
 		time_to_send = netem_skb_cb(skb)->time_to_send;
-		if (time_to_send <= psched_get_time()) {
+		if (time_to_send <= ktime_get_ns()) {
 			rb_erase(p, &q->t_root);
 
 			sch->q.qlen--;
@@ -659,7 +657,7 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
 			if (skb)
 				goto deliver;
 		}
-		qdisc_watchdog_schedule(&q->watchdog, time_to_send);
+		qdisc_watchdog_schedule_ns(&q->watchdog, time_to_send);
 	}
 
 	if (q->qdisc) {
@@ -888,8 +886,8 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt)
 
 	sch->limit = qopt->limit;
 
-	q->latency = qopt->latency;
-	q->jitter = qopt->jitter;
+	q->latency = PSCHED_TICKS2NS(qopt->latency);
+	q->jitter = PSCHED_TICKS2NS(qopt->jitter);
 	q->limit = qopt->limit;
 	q->gap = qopt->gap;
 	q->counter = 0;
@@ -1011,8 +1009,10 @@ static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
 	struct tc_netem_corrupt corrupt;
 	struct tc_netem_rate rate;
 
-	qopt.latency = q->latency;
-	qopt.jitter = q->jitter;
+	qopt.latency = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->latency),
+			     UINT_MAX);
+	qopt.jitter = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->jitter),
+			    UINT_MAX);
 	qopt.limit = q->limit;
 	qopt.loss = q->loss;
 	qopt.gap = q->gap;
-- 
2.7.4