Re: [PATCH v2] rust: time: fix as_micros_ceil() rounding near i64::MAX

Miguel Ojeda <[email protected]> Tue, 11 Aug 2026 14:07:35 +0200

Newsgroups	org.kernel.vger.rust-for-linux
Message-ID	<CANiq72k5uVLXeUurGFE2-Mu=MzTpo0As5hMtMAAd-AjfvkRgXg@mail.gmail.com>

On Fri, Aug 7, 2026 at 3:05 PM FUJITA Tomonori <[email protected]> wrote:
>
> From: FUJITA Tomonori <[email protected]>
>
> The ceiling adjustment used saturating_add(NSEC_PER_USEC - 1) before
> dividing. Once the nanosecond value gets within NSEC_PER_USEC - 1 of
> i64::MAX the addition saturates to i64::MAX, which drops the ceiling
> bias and can yield a result one microsecond too small.
>
> Fixes: fae0cdc12340 ("rust: time: Introduce Delta type")
> Reported-by: Miguel Ojeda <[email protected]>
> Closes: https://lore.kernel.org/rust-for-linux/CANiq72mtS0ABA2JnT5tpz6J9c_mnxY+vyPvghV_ukngWvN8F2w@mail.gmail.com/
> Signed-off-by: FUJITA Tomonori <[email protected]>

Applied to `rust-next` -- thanks everyone!

    Cc: [email protected]

Cheers,
Miguel