On Fri, 31 Aug 2012 08:02:19 -0700
Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> 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).
>
> ...
>
> +
> +/*
> + * 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)); \
> } \
Looks good to me. The patch causes no change in text size for
kernel/sched/fair.o and drivers/cpuidle/governors/menu.o, so it seems
that the cc trickery is working.
I'll add it to my tree for testing - please merge this via your tree.
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