6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Benno Lossin <benno.lossin@xxxxxxxxx> [ 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> --- rust/kernel/types.rs | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) 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`. -- 2.42.0
