Re: [PATCH v3 4/4] rust: devres: implement register_release()

["Benno Lossin" <lossin@kernel.org>]

On Thu Jun 26, 2025 at 4:02 PM CEST, Danilo Krummrich wrote:
> On Thu, Jun 26, 2025 at 01:15:34PM +0200, Danilo Krummrich wrote:
>> On Thu, Jun 26, 2025 at 12:36:23PM +0200, Benno Lossin wrote:
>> > Or, we could change `Release` to be:
>> > 
>> >     pub trait Release {
>> >         type Ptr: ForeignOwnable;
>> > 
>> >         fn release(this: Self::Ptr);
>> >     }
>> > 
>> > and then `register_release` is:
>> > 
>> >     pub fn register_release<T: Release>(dev: &Device<Bound>, data: T::Ptr) -> Result
>> > 
>> > This way, one can store a `Box<T>` and get access to the `T` at the end.
>> 
>> I think this was also the case before? Well, it was P::Borrowed instead.
>> 
>> > Or if they store the value in an `Arc<T>`, they have the option to clone
>> > it and give it to somewhere else.
>> 
>> Anyways, I really like this proposal of implementing the Release trait.
>
> One downside seems to be that the compiler cannot infer T anymore with this
> function signature.

Yeah... That's a bit annoying.

We might be able to add an associated type to `ForeignOwnable` like
`Target` or `Inner` or whatever.

Then we could do:

    pub fn register_release<P>(dev: &Device<Bound>, data: P) -> Result
    where
        P: ForeignOwnable,
        P::Inner: Release<Ptr = P>,

---
Cheers,
Benno