Re: [RFC][PATCH v2] ktime: Fix ktime_divns to do signed division

[Nicolas Pitre]

On Wed, 6 May 2015, John Stultz wrote:

> It was noted that the 32bit implementation of ktime_divns()
> was doing unsigned division and didn't properly handle
> negative values.
> 
> This patch fixes the problem by checking and preserving
> the sign bit, and then reapplying it if appropriate after
> the division, it also changes the return type to a s64
> to make it more obvious this is expected.
> 
[...]
> 
> -# define ktime_divns(kt, div)          (u64)((kt).tv64 / (div))
> +static inline s64 ktime_divns(const ktime_t kt, s64 div)
> +{
> +	/*
> +	 * 32-bit implementation cannot handle negative divisors,
> +	 * so catch them on 64bit as well.
> +	 */
> +	BUG_ON(div < 0);
> +	return (u64)((kt).tv64 / (div))

You forgot to remove the u64 cast?

Is there a reason why it was there originally?


Nicolas
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/