2020-01-03 15:56:39

by Wen Yang

[permalink] [raw]
Subject: [PATCH] timekeeping: improve arithmetic divisions

do_div() does a 64-by-32 division. Use div64_u64()
instead of do_div() if the divisor is u64,
to avoid truncation to 32-bit.

Signed-off-by: Wen Yang <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: [email protected]
---
kernel/time/timekeeping.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index ca69290..bad76c1 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1007,7 +1007,7 @@ static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
tmp *= mult;
rem *= mult;

- do_div(rem, div);
+ rem = div64_u64(rem, div);
*base = tmp + rem;
return 0;
}
--
1.8.3.1