Re: [PATCH v2 1/3] rust: sync: change `<Arc<T> as ForeignOwnable>::PointedTo` to `T`

[Andreas Hindborg]

"Tamir Duberstein" <tamird@xxxxxxxxx> writes:

> On Fri, Feb 7, 2025 at 9:50 AM Andreas Hindborg <a.hindborg@xxxxxxxxxx> wrote:
>>
>> Using `ArcInner` as `PoinedTo` in the `ForeignOwnable` implementation for
>> `Arc` is a bit unfortunate. Using `T` as `PointedTo` does not remove any
>> functionality, but allows `ArcInner` to be private. Further, it allows
>> downstream users to write code that is generic over `Box` and `Arc`, when
>> downstream users need access to `T` after calling `into_foreign`.
>
> I stumbled upon https://github.com/Rust-for-Linux/linux/pull/1036 the
> other day. Boqun, are there any plans to revive this work? It might
> obviate the need for _this_ patch.

I don't think it would help configfs. The configfs patches rely on
getting access to a `T` pointer from `ForeignOwnable::into_foreign`.

In fact, thinking about this, I should probably mandate this in
`ForeignOwnable` API requirements in order to not have soundness hinge
on the implementation of `ForeignOwnable`.

Also I would appreciate that if we want to use a reference to `ArcInner`
rather than a special borrow type, maybe let's do it down the line and
not stall this series on that work.


Best regards,
Andreas Hindborg