Re: [PATCH v2] time: Make sure jiffies_to_msecs() preserves non-zero time periods

From: Arnd Bergmann
Date: Fri Jun 22 2018 - 04:20:01 EST


On Fri, Jun 22, 2018 at 9:54 AM, Geert Uytterhoeven
<geert@xxxxxxxxxxxxxx> wrote:
> For the common cases where 1000 is a multiple of HZ, or HZ is a multiple
> of 1000, jiffies_to_msecs() never returns zero when passed a non-zero
> time period.
>
> However, if HZ > 1000 and not an integer multiple of 1000 (e.g. 1024 or
> 1200, as used on alpha and DECstation), jiffies_to_msecs() may return
> zero for small non-zero time periods. This may break code that relies
> on receiving back a non-zero value.
>
> jiffies_to_usecs() does not need such a fix, as <linux/jiffies.h> does
> not support values of HZ larger than 12287, thus rejecting any
> problematic huge values of HZ.
>
> Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> ---

Looks good to me,

Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>