From 5c55891831f244cf2dde12055b1da8738094fef4 Mon Sep 17 00:00:00 2001 From: Sebastian Reichel Date: Tue, 24 Oct 2023 16:09:35 +0200 Subject: [PATCH] math.h: add DIV_ROUND_UP_NO_OVERFLOW Add a new DIV_ROUND_UP helper, which cannot overflow when big numbers are being used. Signed-off-by: Sebastian Reichel --- include/linux/math.h | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/include/linux/math.h +++ b/include/linux/math.h @@ -36,6 +36,17 @@ #define DIV_ROUND_UP __KERNEL_DIV_ROUND_UP +/** + * DIV_ROUND_UP_NO_OVERFLOW - divide two numbers and always round up + * @n: numerator / dividend + * @d: denominator / divisor + * + * This functions does the same as DIV_ROUND_UP, but internally uses a + * division and a modulo operation instead of math tricks. This way it + * avoids overflowing when handling big numbers. + */ +#define DIV_ROUND_UP_NO_OVERFLOW(n, d) (((n) / (d)) + !!((n) % (d))) + #define DIV_ROUND_DOWN_ULL(ll, d) \ ({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })