From: Eric Paris Date: Wed, 13 Oct 2010 21:50:02 +0000 (-0400) Subject: kernel: rounddown helper function X-Git-Tag: v2.6.37-rc1~218^2~7 X-Git-Url: https://bbs.cooldavid.org/git/?p=net-next-2.6.git;a=commitdiff_plain;h=686a0f3d71203bbfcc186900bbb8ac2cfc3d803c kernel: rounddown helper function The roundup() helper function will round a given value up to a multiple of another given value. aka roundup(11, 7) would give 14 = 7 * 2. This new function does the opposite. It will round a given number down to the nearest multiple of the second number: rounddown(11, 7) would give 7. I need this in some future SELinux code and can carry the macro myself, but figured I would put it in the core kernel so others might find and use it if need be. Signed-off-by: Eric Paris Signed-off-by: James Morris --- diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 2b0a35e6bc6..6d6eea7f7b1 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -59,6 +59,12 @@ extern const char linux_proc_banner[]; #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) #define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y)) +#define rounddown(x, y) ( \ +{ \ + typeof(x) __x = (x); \ + __x - (__x % (y)); \ +} \ +) #define DIV_ROUND_CLOSEST(x, divisor)( \ { \ typeof(divisor) __divisor = divisor; \