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-rw-r--r--arch/tile/kernel/time.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/tile/kernel/time.c b/arch/tile/kernel/time.c
index 5d10642db63e..462dcd0c1700 100644
--- a/arch/tile/kernel/time.c
+++ b/arch/tile/kernel/time.c
@@ -236,7 +236,15 @@ cycles_t ns2cycles(unsigned long nsecs)
* clock frequency.
*/
struct clock_event_device *dev = &__raw_get_cpu_var(tile_timer);
- return ((u64)nsecs * dev->mult) >> dev->shift;
+
+ /*
+ * as in clocksource.h and x86's timer.h, we split the calculation
+ * into 2 parts to avoid unecessary overflow of the intermediate
+ * value. This will not lead to any loss of precision.
+ */
+ u64 quot = (u64)nsecs >> dev->shift;
+ u64 rem = (u64)nsecs & ((1ULL << dev->shift) - 1);
+ return quot * dev->mult + ((rem * dev->mult) >> dev->shift);
}
void update_vsyscall_tz(void)