Re: [PATCH v2] rust: time: Avoid 64-bit integer division on 32-bit architectures

[Andreas Hindborg <a.hindborg@kernel.org>]

FUJITA Tomonori <fujita.tomonori@gmail.com> writes:

> Avoid 64-bit integer division that 32-bit architectures don't
> implement generally. This uses ktime_to_us() and ktime_to_ms()
> instead.
>
> The time abstraction needs i64 / u32 division so C's div_s64() can be
> used but ktime_to_us() and ktime_to_ms() provide a simpler solution
> for this time abstraction problem on 32-bit architectures.
>
> 32-bit ARM is the only 32-bit architecture currently supported by
> Rust. Using the cfg attribute, only 32-bit architectures will call
> ktime_to_us() and ktime_to_ms(), while the other 64-bit architectures
> will continue to use the current code as-is to avoid the overhead.
>
> One downside of calling the C's functions is that the as_micros/millis
> methods can no longer be const fn. We stick with the simpler approach
> unless there's a compelling need for a const fn.
>
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Suggested-by: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>

Looks good to me.


Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>


Best regards,
Andreas Hindborg