diff mbox series

[v3,02/13] rust: sync: add `assume_init` to `UniqueArc`

Message ID 20230329223239.138757-3-y86-dev@protonmail.com
State New
Headers
Series Rust pin-init API for pinned initialization of structs |

Commit Message

y86-dev March 29, 2023, 10:32 p.m. UTC 
  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>
---
 rust/kernel/sync/arc.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

--
2.39.2

Comments

Wedson Almeida Filho March 30, 2023, 4:13 a.m. UTC | #1 
On Wed, 29 Mar 2023 at 19:33, <y86-dev@protonmail.com> wrote:
>
> 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>
Andreas Hindborg March 30, 2023, 12:18 p.m. UTC | #2 
y86-dev@protonmail.com writes:

> 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: Andreas Hindborg <a.hindborg@samsung.com>
Alice Ryhl March 30, 2023, 1:33 p.m. UTC | #3 
On 3/30/23 00:32, y86-dev@protonmail.com wrote:
> 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: Alice Ryhl <aliceryhl@google.com>
diff mbox series

Patch

diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index f2f1c83d72ba..16ec174637b2 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