From 686a0f3d71203bbfcc186900bbb8ac2cfc3d803c Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Wed, 13 Oct 2010 17:50:02 -0400 Subject: 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 --- include/linux/kernel.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 2b0a35e6bc69..6d6eea7f7b1e 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; \ -- cgit v1.2.3 From b28efd54d9d5c8005a29cd8782335beb9daaa32d Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Wed, 13 Oct 2010 17:50:08 -0400 Subject: kernel: roundup should only reference arguments once Currently the roundup macro references it's arguments more than one time. This patch changes it so it will only use its arguments once. Suggested-by: Andrew Morton Signed-off-by: Eric Paris Signed-off-by: James Morris --- include/linux/kernel.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 6d6eea7f7b1e..1759ba5adce8 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -58,7 +58,12 @@ 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 roundup(x, y) ( \ +{ \ + typeof(y) __y = y; \ + (((x) + (__y - 1)) / __y) * __y; \ +} \ +) #define rounddown(x, y) ( \ { \ typeof(x) __x = (x); \ -- cgit v1.2.3