Commit 2e704f18 authored by Benno Lossin's avatar Benno Lossin Committed by Miguel Ojeda
Browse files

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



`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: default avatarGary Guo <gary@garyguo.net>
Reviewed-by: default avatarMartin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: default avatarBenno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20230814084602.25699-11-benno.lossin@proton.me


Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 674b1c7a

rust/kernel/init.rs

+7 −1
Original line number Diff line number Diff line
@@ -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>,