Messages in this thread Patch in this message | | | Date | Wed, 14 Jun 2023 11:53:28 +0000 | Subject | [PATCH] rust: make `UnsafeCell` the outer type in `Opaque` | From | Alice Ryhl <> |
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When combining `UnsafeCell` with `MaybeUninit`, it is idiomatic to use `UnsafeCell` as the outer type. Intuitively, this is because a `MaybeUninit<T>` might not contain a `T`, but we always want the effect of the `UnsafeCell`, even if the inner value is uninitialized.
Now, strictly speaking, this doesn't really make a difference. The compiler will always apply the `UnsafeCell` effect even if the inner value is uninitialized. But I think we should follow the convention here.
Signed-off-by: Alice Ryhl <aliceryhl@google.com> --- rust/kernel/types.rs | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index 1e5380b16ed5..fb41635f1e1f 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -224,17 +224,17 @@ fn drop(&mut self) { /// /// This is meant to be used with FFI objects that are never interpreted by Rust code. #[repr(transparent)] -pub struct Opaque<T>(MaybeUninit<UnsafeCell<T>>); +pub struct Opaque<T>(UnsafeCell<MaybeUninit<T>>); impl<T> Opaque<T> { /// Creates a new opaque value. pub const fn new(value: T) -> Self { - Self(MaybeUninit::new(UnsafeCell::new(value))) + Self(UnsafeCell::new(MaybeUninit::new(value))) } /// Creates an uninitialised value. pub const fn uninit() -> Self { - Self(MaybeUninit::uninit()) + Self(UnsafeCell::new(MaybeUninit::uninit())) } /// Creates a pin-initializer from the given initializer closure. @@ -258,7 +258,7 @@ pub fn ffi_init(init_func: impl FnOnce(*mut T)) -> impl PinInit<Self> { /// Returns a raw pointer to the opaque data. pub fn get(&self) -> *mut T { - UnsafeCell::raw_get(self.0.as_ptr()) + UnsafeCell::get(&self.0).cast::<T>() } /// Gets the value behind `this`. @@ -266,7 +266,7 @@ pub fn get(&self) -> *mut T { /// This function is useful to get access to the value without creating intermediate /// references. pub const fn raw_get(this: *const Self) -> *mut T { - UnsafeCell::raw_get(this.cast::<UnsafeCell<T>>()) + UnsafeCell::raw_get(this.cast::<UnsafeCell<MaybeUninit<T>>>()).cast::<T>() } } base-commit: d2e3115d717197cb2bc020dd1f06b06538474ac3 -- 2.41.0.162.gfafddb0af9-goog
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