This is a note to let you know that I've just added the patch titled
rust: types: make `Opaque` be `!Unpin`
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rust-types-make-opaque-be-unpin.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f87ce940559e9da9e39f3fd1388362e2ecd7971f
Author: Benno Lossin <benno.lossin@xxxxxxxxx>
Date: Fri Jun 30 15:03:23 2023 +0000
rust: types: make `Opaque` be `!Unpin`
[ Upstream commit 0b4e3b6f6b79b1add04008a6ceaaf661107e8902 ]
Adds a `PhantomPinned` field to `Opaque<T>`. This removes the last Rust
guarantee: the assumption that the type `T` can be freely moved. This is
not the case for many types from the C side (e.g. if they contain a
`struct list_head`). This change removes the need to add a
`PhantomPinned` field manually to Rust structs that contain C structs
which must not be moved.
Signed-off-by: Benno Lossin <benno.lossin@xxxxxxxxx>
Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>
Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Reviewed-by: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230630150216.109789-1-benno.lossin@xxxxxxxxx
Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index c0b8bb1a75393..50cbd767ea9dd 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -6,7 +6,7 @@
use alloc::boxed::Box;
use core::{
cell::UnsafeCell,
- marker::PhantomData,
+ marker::{PhantomData, PhantomPinned},
mem::MaybeUninit,
ops::{Deref, DerefMut},
ptr::NonNull,
@@ -206,17 +206,26 @@ 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>(UnsafeCell<MaybeUninit<T>>);
+pub struct Opaque<T> {
+ value: UnsafeCell<MaybeUninit<T>>,
+ _pin: PhantomPinned,
+}
impl<T> Opaque<T> {
/// Creates a new opaque value.
pub const fn new(value: T) -> Self {
- Self(UnsafeCell::new(MaybeUninit::new(value)))
+ Self {
+ value: UnsafeCell::new(MaybeUninit::new(value)),
+ _pin: PhantomPinned,
+ }
}
/// Creates an uninitialised value.
pub const fn uninit() -> Self {
- Self(UnsafeCell::new(MaybeUninit::uninit()))
+ Self {
+ value: UnsafeCell::new(MaybeUninit::uninit()),
+ _pin: PhantomPinned,
+ }
}
/// Creates a pin-initializer from the given initializer closure.
@@ -240,7 +249,7 @@ 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::get(&self.0).cast::<T>()
+ UnsafeCell::get(&self.value).cast::<T>()
}
/// Gets the value behind `this`.
