Re: [PATCH 1/4] rust: types: implement ForeignOwnable for ARef<T>

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Missing `#[inline]` annotations on small forwarding trait methods in `ForeignOwnable` implementation for `ARef<T>`.
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commit 62543d419c62c8206acbd8b76f07e5198b71442e
Author: Danilo Krummrich <dakr@kernel.org>

rust: types: implement ForeignOwnable for ARef<T>

This commit implements ForeignOwnable for ARef<T>, making it possible for C
code to own an ARef<T>. It sets BorrowedMut to &T to match the shared
ownership semantics of the underlying reference-counted type.

> diff --git a/rust/kernel/sync/aref.rs b/rust/kernel/sync/aref.rs
> index 9989f56d06052..82907383c44b5 100644
> --- a/rust/kernel/sync/aref.rs
> +++ b/rust/kernel/sync/aref.rs

[ ... ]

> +    type Borrowed<'a> = &'a T;
> +    type BorrowedMut<'a> = &'a T;
> +
> +    fn into_foreign(self) -> *mut c_void {

[Severity: Low]
This isn't a bug, but should this method be annotated with #[inline]?
According to the Rust subsystem guidelines, small forwarding functions in
abstractions should be annotated with #[inline].

> +        ARef::into_raw(self).as_ptr().cast()
> +    }
> +
> +    unsafe fn from_foreign(ptr: *mut c_void) -> Self {

[Severity: Low]
This isn't a bug, but should from_foreign() also have an #[inline]
annotation since it is a small wrapper method?

> +        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
> +        // call to `Self::into_foreign`.
> +        let ptr = unsafe { NonNull::new_unchecked(ptr.cast()) };
> +
> +        // SAFETY: `ptr` came from `into_foreign`, which consumed an `ARef` without decrementing
> +        // the refcount, so we can transfer the ownership to the new `ARef`.
> +        unsafe { ARef::from_raw(ptr) }
> +    }
> +
> +    unsafe fn borrow<'a>(ptr: *mut c_void) -> &'a T {

[Severity: Low]
This isn't a bug, but similar to the above, should borrow() be annotated
with #[inline]?

> +        // SAFETY: The safety requirements of this method ensure that the object remains alive and
> +        // immutable for the duration of 'a.
> +        unsafe { &*ptr.cast() }
> +    }
> +
> +    unsafe fn borrow_mut<'a>(ptr: *mut c_void) -> &'a T {

[Severity: Low]
This isn't a bug, but does borrow_mut() need an #[inline] annotation here
as well?

> +        // SAFETY: The safety requirements for `borrow_mut` are a superset of the safety
> +        // requirements for `borrow`.
> +        unsafe { <Self as ForeignOwnable>::borrow(ptr) }
> +    }
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260530143541.229628-2-phasta@kernel.org?part=1