Commit 9d29c682 authored by Benno Lossin's avatar Benno Lossin Committed by Miguel Ojeda
Browse files

rust: pin-init: move impl `Zeroable` for `Opaque` and `Option<KBox<T>>` into the kernel crate 



In order to make pin-init a standalone crate, move kernel-specific code
directly into the kernel crate. Since `Opaque<T>` and `KBox<T>` are part
of the kernel, move their `Zeroable` implementation into the kernel
crate.

Signed-off-by: default avatarBenno Lossin <benno.lossin@proton.me>
Tested-by: default avatarAndreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: default avatarFiona Behrens <me@kloenk.dev>
Link: https://lore.kernel.org/r/20250308110339.2997091-10-benno.lossin@proton.me


Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 114ca41f

rust/kernel/alloc/kbox.rs

+7 −1
Original line number Diff line number Diff line
@@ -15,7 +15,7 @@ 
use core::ptr::NonNull;

use core::result::Result;



use crate::init::{InPlaceWrite, Init, PinInit};

use crate::init::{InPlaceWrite, Init, PinInit, Zeroable};

use crate::init_ext::InPlaceInit;

use crate::types::ForeignOwnable;
@@ -100,6 +100,12 @@ 
/// ```

pub type KVBox<T> = Box<T, super::allocator::KVmalloc>;



// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).

//

// In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant and there

// is no problem with a VTABLE pointer being null.

unsafe impl<T: ?Sized, A: Allocator> Zeroable for Option<Box<T, A>> {}



// SAFETY: `Box` is `Send` if `T` is `Send` because the `Box` owns a `T`.

unsafe impl<T, A> Send for Box<T, A>

where

rust/kernel/types.rs

+4 −1
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 


//! Kernel types.



use crate::init::{self, PinInit};

use crate::init::{self, PinInit, Zeroable};

use core::{

    cell::UnsafeCell,

    marker::{PhantomData, PhantomPinned},
@@ -309,6 +309,9 @@ pub struct Opaque<T> { 
    _pin: PhantomPinned,

}



// SAFETY: `Opaque<T>` allows the inner value to be any bit pattern, including all zeros.

unsafe impl<T> Zeroable for Opaque<T> {}



impl<T> Opaque<T> {

    /// Creates a new opaque value.

    pub const fn new(value: T) -> Self {

rust/pin-init/src/lib.rs

+1 −7
Original line number Diff line number Diff line
@@ -211,10 +211,7 @@ 
//! [`pin_data`]: ::macros::pin_data

//! [`pin_init!`]: crate::pin_init!



use crate::{

    alloc::KBox,

    types::{Opaque, ScopeGuard},

};

use crate::{alloc::KBox, types::ScopeGuard};

use core::{

    cell::UnsafeCell,

    convert::Infallible,
@@ -1342,8 +1339,6 @@ macro_rules! 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>,
@@ -1358,7 +1353,6 @@ macro_rules! impl_zeroable { 
    //

    // In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant.

    {<T: ?Sized>} Option<NonNull<T>>,

    {<T: ?Sized>} Option<KBox<T>>,



    // SAFETY: `null` pointer is valid.

    //