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rust: init: implement Zeroable for UnsafeCell<T> and Opaque<T>

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`UnsafeCell<T>` and `T` have the same layout so if `T` is `Zeroable`
then so should `UnsafeCell<T>` be. This allows using the derive macro
for `Zeroable` on types that contain an `UnsafeCell<T>`.
Since `Opaque<T>` contains a `MaybeUninit<T>`, all bytes zero is a valid
bit pattern for that type.

Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20230814084602.25699-11-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Benno Lossin 2023-08-14 08:47:32 +00:00 committed by Miguel Ojeda
parent 674b1c7aed
commit 2e704f1883
1 changed files with 7 additions and 1 deletions
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8
rust/kernel/init.rs
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@ -202,11 +202,12 @@
use crate::{
error::{self, Error},
sync::UniqueArc,
types::ScopeGuard,
types::{Opaque, ScopeGuard},
};
use alloc::boxed::Box;
use core::{
alloc::AllocError,
cell::UnsafeCell,
convert::Infallible,
marker::PhantomData,
mem::MaybeUninit,
@ -1151,6 +1152,11 @@ impl_zeroable! {
// SAFETY: Type is allowed to take any value, including all zeros.
{<T>} MaybeUninit<T>,
// SAFETY: Type is allowed to take any value, including all zeros.
{<T>} Opaque<T>,
// SAFETY: `T: Zeroable` and `UnsafeCell` is `repr(transparent)`.
{<T: ?Sized + Zeroable>} UnsafeCell<T>,
// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).
Option<NonZeroU8>, Option<NonZeroU16>, Option<NonZeroU32>, Option<NonZeroU64>,