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rust: init: make PinInit<T, E> a supertrait of Init<T, E>

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Remove the blanket implementation of `PinInit<T, E> for I where I:
Init<T, E>`. This blanket implementation prevented custom types that
implement `PinInit`.

Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20230814084602.25699-12-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Benno Lossin 2023-08-14 08:47:40 +00:00 committed by Miguel Ojeda
parent 2e704f1883
commit 1a8076ac6d
2 changed files with 20 additions and 13 deletions
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21
rust/kernel/init.rs
View File

@ -799,7 +799,7 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
///
/// [`Arc<T>`]: crate::sync::Arc
#[must_use = "An initializer must be used in order to create its value."]
pub unsafe trait Init<T: ?Sized, E = Infallible>: Sized {
pub unsafe trait Init<T: ?Sized, E = Infallible>: PinInit<T, E> {
/// Initializes `slot`.
///
/// # Safety
@ -810,18 +810,6 @@ pub unsafe trait Init<T: ?Sized, E = Infallible>: Sized {
unsafe fn __init(self, slot: *mut T) -> Result<(), E>;
}
// SAFETY: Every in-place initializer can also be used as a pin-initializer.
unsafe impl<T: ?Sized, E, I> PinInit<T, E> for I
where
I: Init<T, E>,
{
unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
// SAFETY: `__init` meets the same requirements as `__pinned_init`, except that it does not
// require `slot` to not move after init.
unsafe { self.__init(slot) }
}
}
/// Creates a new [`PinInit<T, E>`] from the given closure.
///
/// # Safety
@ -964,6 +952,13 @@ unsafe impl<T, E> Init<T, E> for T {
}
}
// SAFETY: Every type can be initialized by-value. `__pinned_init` calls `__init`.
unsafe impl<T, E> PinInit<T, E> for T {
unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
unsafe { self.__init(slot) }
}
}
/// Smart pointer that can initialize memory in-place.
pub trait InPlaceInit<T>: Sized {
/// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this

12
rust/kernel/init/__internal.rs
View File

@ -32,6 +32,18 @@ where
}
}
// SAFETY: While constructing the `InitClosure`, the user promised that it upholds the
// `__pinned_init` invariants.
unsafe impl<T: ?Sized, F, E> PinInit<T, E> for InitClosure<F, T, E>
where
F: FnOnce(*mut T) -> Result<(), E>,
{
#[inline]
unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
(self.0)(slot)
}
}
/// This trait is only implemented via the `#[pin_data]` proc-macro. It is used to facilitate
/// the pin projections within the initializers.
///