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author | Alice Ryhl <aliceryhl@google.com> | 2023-06-14 11:53:28 +0000 |
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committer | Miguel Ojeda <ojeda@kernel.org> | 2023-08-10 01:18:34 +0200 |
commit | 35cad617df2eeef8440a38e82bb2d81ae32ca50d (patch) | |
tree | c242223c7b6afcd9846da86b59d6eeccfefbcda7 | |
parent | 0bb1c9282e2cb38d199347d1d96b77f208b64810 (diff) | |
download | linux-stable-35cad617df2eeef8440a38e82bb2d81ae32ca50d.tar.gz linux-stable-35cad617df2eeef8440a38e82bb2d81ae32ca50d.tar.bz2 linux-stable-35cad617df2eeef8440a38e82bb2d81ae32ca50d.zip |
rust: make `UnsafeCell` the outer type in `Opaque`
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>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Link: https://lore.kernel.org/r/20230614115328.2825961-1-aliceryhl@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
-rw-r--r-- | rust/kernel/types.rs | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index d479f8da8f38..c0b8bb1a7539 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -206,17 +206,17 @@ impl<T, F: FnOnce(T)> Drop for ScopeGuard<T, F> { /// /// 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. @@ -240,7 +240,7 @@ impl<T> Opaque<T> { /// 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`. @@ -248,7 +248,7 @@ impl<T> Opaque<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>() } } |