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netem: remove unnecessary 64 bit modulus 

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: 99803171ef ("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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2017-11-14 11:27:02 -08:00 committed by David S. Miller
parent bce552fd6f
commit 9b0ed89172
1 changed files with 3 additions and 3 deletions
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6
net/sched/sch_netem.c
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@ -312,9 +312,9 @@ static bool loss_event(struct netem_sched_data *q)
* std deviation sigma. Uses table lookup to approximate the desired * std deviation sigma. Uses table lookup to approximate the desired
* distribution, and a uniformly-distributed pseudo-random source. * 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, struct crndstate *state,
const struct disttable *dist) const struct disttable *dist)
{ {
s64 x; s64 x;
long t; long t;
@ -327,7 +327,7 @@ static s64 tabledist(s64 mu, s64 sigma,
/* default uniform distribution */ /* default uniform distribution */
if (dist == NULL) if (dist == NULL)
return (rnd % (2*sigma)) - sigma + mu; return (rnd % (2 * sigma)) - sigma + mu;
t = dist->table[rnd % dist->size]; t = dist->table[rnd % dist->size];
x = (sigma % NETEM_DIST_SCALE) * t; x = (sigma % NETEM_DIST_SCALE) * t;