Re: [PATCH net-next v3 4/8] rust: time: Implement addition of Ktime and Delta

[FUJITA Tomonori <fujita.tomonori@gmail.com>]

On Thu, 17 Oct 2024 18:33:23 +0200
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> wrote:

> On Thu, Oct 17, 2024 at 11:31 AM FUJITA Tomonori
> <fujita.tomonori@gmail.com> wrote:
>>
>> We could add the Rust version of add_safe method. But looks like
>> ktime_add_safe() is used by only some core systems so we don't need to
>> add it now?
> 
> There was some discussion in the past about this -- I wrote there a
> summary of the `add` variants:
> 
>     https://lore.kernel.org/rust-for-linux/CANiq72ka4UvJzb4dN12fpA1WirgDHXcvPurvc7B9t+iPUfWnew@mail.gmail.com/
> 
> I think this is a case where following the naming of the C side would
> be worse, i.e. where it is worth not applying our usual guideline.
> Calling something `_safe`/`_unsafe` like the C macros would be quite
> confusing for Rust.
> 
> Personally, I would prefer that we stay consistent, which will help
> when dealing with more code. That is (from the message above):
> 
>   - No suffix: not supposed to wrap. So, in Rust, map it to operators.
>   - `_unsafe()`: wraps. So, in Rust, map it to `wrapping` methods.
>   - `_safe()`: saturates. So, in Rust, map it to `saturating` methods.

Can we add the above to Documentation/rust/coding-guidelines.rst?

I think that it's better than adding the similar comment to every
function that performs arithmetic.