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Commit b6d86d3d authored by Guenter Roeck's avatar Guenter Roeck
Browse files

linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends 



DIV_ROUND_CLOSEST returns a bad result for negative dividends:
	DIV_ROUND_CLOSEST(-2, 2) = 0

Most of the time this does not matter. However, in the hardware monitoring
subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be
negative (such as temperatures).

Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Acked-by: default avatarJean Delvare <khali@linux-fr.org>
parent 4cbe5a55

include/linux/kernel.h

+10 −2
Original line number Diff line number Diff line
@@ -82,10 +82,18 @@ 
	__x - (__x % (y));				\

}							\

)



/*

 * Divide positive or negative dividend by positive divisor and round

 * to closest integer. Result is undefined for negative divisors.

 */

#define DIV_ROUND_CLOSEST(x, divisor)(			\

{							\

	typeof(divisor) __divisor = divisor;		\

	(((x) + ((__divisor) / 2)) / (__divisor));	\

	typeof(x) __x = x;				\

	typeof(divisor) __d = divisor;			\

	(((typeof(x))-1) >= 0 || (__x) >= 0) ?		\

		(((__x) + ((__d) / 2)) / (__d)) :	\

		(((__x) - ((__d) / 2)) / (__d));	\

}							\

)