[net-next,v2,2/2] netem: remove unnecessary 64 bit modulus

Message ID 20171114192702.31193-3-sthemmin@microsoft.com
State Accepted
Delegated to: David Miller
Headers show
Series
  • netem: fix compilation on 32 bit
Related show

Commit Message

Stephen Hemminger Nov. 14, 2017, 7:27 p.m.
Fix compilation on 32 bit platforms (where doing modulus operation
with 64 bit requires extra glibc functions) by truncation.
The jitter for table distribution is limited to a 32 bit value
because random numbers are scaled as 32 bit value.

Also fix some whitespace.

Fixes: 99803171ef04 ("netem: add uapi to express delay and jitter in nanoseconds")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 net/sched/sch_netem.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Patch

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 644323d6081c..dd70924cbcdf 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -312,9 +312,9 @@  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 s64 tabledist(s64 mu, s64 sigma,
+static s64 tabledist(s64 mu, s32 sigma,
 		     struct crndstate *state,
-			 const struct disttable *dist)
+		     const struct disttable *dist)
 {
 	s64 x;
 	long t;
@@ -327,7 +327,7 @@  static s64 tabledist(s64 mu, s64 sigma,
 
 	/* default uniform distribution */
 	if (dist == NULL)
-		return (rnd % (2*sigma)) - sigma + mu;
+		return (rnd % (2 * sigma)) - sigma + mu;
 
 	t = dist->table[rnd % dist->size];
 	x = (sigma % NETEM_DIST_SCALE) * t;