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rust: kernel: reorder ForeignOwnable items

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`{into,from}_foreign` before `borrow` is slightly more logical.

This removes an inconsistency with `kbox.rs` which already uses this
ordering.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Link: https://lore.kernel.org/r/20241120-borrow-mut-v6-5-80dbadd00951@gmail.com
[ Reworded title slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Tamir Duberstein
2024-11-20 06:46:04 -05:00
committed by Miguel Ojeda
parent 14686571a9
commit c6b97538c2
2 changed files with 20 additions and 20 deletions
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20
rust/kernel/sync/arc.rs
View File

@@ -349,16 +349,6 @@ impl<T: 'static> ForeignOwnable for Arc<T> {
ManuallyDrop::new(self).ptr.as_ptr().cast()
}
unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> ArcBorrow<'a, T> {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
let inner = unsafe { NonNull::new_unchecked(ptr.cast::<ArcInner<T>>()) };
// SAFETY: The safety requirements of `from_foreign` ensure that the object remains alive
// for the lifetime of the returned value.
unsafe { ArcBorrow::new(inner) }
}
unsafe fn from_foreign(ptr: *mut crate::ffi::c_void) -> Self {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
@@ -369,6 +359,16 @@ impl<T: 'static> ForeignOwnable for Arc<T> {
// holds a reference count increment that is transferrable to us.
unsafe { Self::from_inner(inner) }
}
unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> ArcBorrow<'a, T> {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
let inner = unsafe { NonNull::new_unchecked(ptr.cast::<ArcInner<T>>()) };
// SAFETY: The safety requirements of `from_foreign` ensure that the object remains alive
// for the lifetime of the returned value.
unsafe { ArcBorrow::new(inner) }
}
}
impl<T: ?Sized> Deref for Arc<T> {

20
rust/kernel/types.rs
View File

@@ -31,14 +31,6 @@ pub trait ForeignOwnable: Sized {
/// [`ForeignOwnable::try_from_foreign`] can result in undefined behavior.
fn into_foreign(self) -> *mut crate::ffi::c_void;
/// Borrows a foreign-owned object.
///
/// # Safety
///
/// `ptr` must have been returned by a previous call to [`ForeignOwnable::into_foreign`] for
/// which a previous matching [`ForeignOwnable::from_foreign`] hasn't been called yet.
unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> Self::Borrowed<'a>;
/// Converts a foreign-owned object back to a Rust-owned one.
///
/// # Safety
@@ -67,6 +59,14 @@ pub trait ForeignOwnable: Sized {
unsafe { Some(Self::from_foreign(ptr)) }
}
}
/// Borrows a foreign-owned object.
///
/// # Safety
///
/// `ptr` must have been returned by a previous call to [`ForeignOwnable::into_foreign`] for
/// which a previous matching [`ForeignOwnable::from_foreign`] hasn't been called yet.
unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> Self::Borrowed<'a>;
}
impl ForeignOwnable for () {
@@ -76,9 +76,9 @@ impl ForeignOwnable for () {
core::ptr::NonNull::dangling().as_ptr()
}
unsafe fn borrow<'a>(_: *mut crate::ffi::c_void) -> Self::Borrowed<'a> {}
unsafe fn from_foreign(_: *mut crate::ffi::c_void) -> Self {}
unsafe fn borrow<'a>(_: *mut crate::ffi::c_void) -> Self::Borrowed<'a> {}
}
/// Runs a cleanup function/closure when dropped.