From: Stephen Hemminger <stephen@networkplumber.org>
Date: Tue, 14 Nov 2017 11:27:01 -0800
Subject: netem: use 64 bit divide by rate
Patch-mainline: v4.15-rc1
Git-commit: bce552fd6f6e37f9567c85c4f0d6d1987eef379f
References: bsc#1109837

Since times are now expressed in nanosecond, need to now do
true 64 bit divide. Old code would truncate rate at 32 bits.
Rename function to better express current usage.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/sched/sch_netem.c |   11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -340,10 +340,8 @@ static s64 tabledist(s64 mu, s64 sigma,
 	return  x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
 }
 
-static u64 packet_len_2_sched_time(unsigned int len,
-				   struct netem_sched_data *q)
+static u64 packet_time_ns(u64 len, const struct netem_sched_data *q)
 {
-	u64 offset;
 	len += q->packet_overhead;
 
 	if (q->cell_size) {
@@ -353,9 +351,8 @@ static u64 packet_len_2_sched_time(unsig
 			cells++;
 		len = cells * (q->cell_size + q->cell_overhead);
 	}
-	offset = (u64)len * NSEC_PER_SEC;
-	do_div(offset, q->rate);
-	return offset;
+
+	return div64_u64(len * NSEC_PER_SEC, q->rate);
 }
 
 static void tfifo_reset(struct Qdisc *sch)
@@ -557,7 +554,7 @@ static int netem_enqueue(struct sk_buff
 				now = last->time_to_send;
 			}
 
-			delay += packet_len_2_sched_time(qdisc_pkt_len(skb), q);
+			delay += packet_time_ns(qdisc_pkt_len(skb), q);
 		}
 
 		cb->time_to_send = now + delay;