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

[Oliver Mangold]

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
:/

> > +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`?

Best,

Oliver