[PATCH 2/2] sched/nohz: fix overflow error in scheduler_tick_max_deferment()

From: Kevin Hilman
Date: Tue Jun 18 2013 - 19:58:49 EST

The conversion of the max deferment from usecs to nsecs can easily
overflow on platforms where a long is 32-bits. To fix, cast the usecs
value to u64 before multiplying by NSECS_PER_USEC.

This was discovered on 32-bit ARM platform when extending the max
deferment value.

Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Signed-off-by: Kevin Hilman <khilman@xxxxxxxxxx>
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b5d3f99..b506722 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2765,7 +2765,7 @@ u64 scheduler_tick_max_deferment(void)
if (time_before_eq(next, now))
return 0;

- return jiffies_to_usecs(next - now) * NSEC_PER_USEC;
+ return (u64)jiffies_to_usecs(next - now) * NSEC_PER_USEC;


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