Messages in this thread Patch in this message | | | Date | Fri, 31 Mar 2023 21:52:27 +0000 | From | y86-dev@protonma ... | Subject | [PATCH v4 04/15] rust: sync: add `assume_init` to `UniqueArc` |
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From: Benno Lossin <y86-dev@protonmail.com>
Adds the `assume_init` function to `UniqueArc<MaybeUninit<T>>` that unsafely assumes the value to be initialized and yields a value of type `UniqueArc<T>`. This function is used when manually initializing the pointee of an `UniqueArc`.
Signed-off-by: Benno Lossin <y86-dev@protonmail.com> Reviewed-by: Wedson Almeida Filho <walmeida@microsoft.com> Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> --- rust/kernel/sync/arc.rs | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index aa7135f0f238..eee7008e5e3e 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -489,6 +489,17 @@ impl<T> UniqueArc<MaybeUninit<T>> { /// Converts a `UniqueArc<MaybeUninit<T>>` into a `UniqueArc<T>` by writing a value into it. pub fn write(mut self, value: T) -> UniqueArc<T> { self.deref_mut().write(value); + // SAFETY: We just wrote the value to be initialized. + unsafe { self.assume_init() } + } + + /// Unsafely assume that `self` is initialized. + /// + /// # Safety + /// + /// The caller guarantees that the value behind this pointer has been initialized. It is + /// *immediate* UB to call this when the value is not initialized. + pub unsafe fn assume_init(self) -> UniqueArc<T> { let inner = ManuallyDrop::new(self).inner.ptr; UniqueArc { // SAFETY: The new `Arc` is taking over `ptr` from `self.inner` (which won't be -- 2.39.2
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