Re: [PATCH v7 05/16] rust: types: add `Opaque::pin_init`

[Gary Guo]

On Thu, 19 Dec 2024 18:04:07 +0100
Danilo Krummrich <dakr@xxxxxxxxxx> wrote:

> Analogous to `Opaque::new` add `Opaque::pin_init`, which instead of a
> value `T` takes a `PinInit<T>` and returns a `PinInit<Opaque<T>>`.
> 
> Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> Suggested-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>

Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>

> ---
>  rust/kernel/types.rs | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> index ec6457bb3084..3aea6af9a0bc 100644
> --- a/rust/kernel/types.rs
> +++ b/rust/kernel/types.rs
> @@ -281,6 +281,17 @@ pub const fn uninit() -> Self {
>          }
>      }
>  
> +    /// Create an opaque pin-initializer from the given pin-initializer.
> +    pub fn pin_init(slot: impl PinInit<T>) -> impl PinInit<Self> {
> +        Self::ffi_init(|ptr: *mut T| {
> +            // SAFETY:
> +            //   - `ptr` is a valid pointer to uninitialized memory,
> +            //   - `slot` is not accessed on error; the call is infallible,
> +            //   - `slot` is pinned in memory.
> +            let _ = unsafe { init::PinInit::<T>::__pinned_init(slot, ptr) };
> +        })
> +    }
> +
>      /// Creates a pin-initializer from the given initializer closure.
>      ///
>      /// The returned initializer calls the given closure with the pointer to the inner `T` of this