Re: [PATCH v10 1/5] rust: types: Add Ownable/Owned types

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

"Benno Lossin" <lossin@kernel.org> writes:

> On Wed Jun 18, 2025 at 11:34 AM CEST, Oliver Mangold wrote:
>> On 250514 1132, Benno Lossin wrote:
>>> On Fri May 2, 2025 at 11:02 AM CEST, Oliver Mangold wrote:
>>>
>>> > +/// - That the C code follows the usual mutable reference requirements. That is, the kernel will
>>> > +///   never mutate the [`Ownable`] (excluding internal mutability that follows the usual rules)
>>> > +///   while Rust owns it.
>>>
>>> I feel like this requirement is better put on the `Owned::from_raw`
>>> function.
>>
>> Thinking about it some more, the problem I see here is that if the type
>> implements `OwnableMut` this requirement changes from "never mutate" to
>> "never access at all".
>>
>> The safety requirements between `Ownable`, `OwnableMut`, `RefCounted`,
>> `OwnableRefCounted` and `AlwaysRefCounted` are interacting, but I agree
>> that, when looking at it a certain way, `Owned::from_raw()` is the place
>> where one would expect these to be. I'm not sure anymore what is best here
>> :/
>
> I still think `Owned::from_raw` is the correct place to put this.
>
>>
>>> > +pub unsafe trait OwnableMut: Ownable {}
>>>
>>> I don't like the name, but at the same time I also have no good
>>> suggestion :( I'll think some more about it.
>>
>> There was already a bit of discussion about it. I had my own implementation of this
>> where I used the names `UniqueRefCounted` and `UniqueRef`, but after discovering
>> this version from Asahi Lina, I took it as it was, keeping the name.
>>
>> No one else came up with different suggestions so far, so maybe we should just leave it
>> at `Owned`/`Ownable`?
>
> I'm just hung up on the `Mut` part... Haven't come up with a good
> replacement yet.

What do you dislike about the xxxxMut pattern?


Best regards,
Andreas Hindborg