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author | Benno Lossin <benno.lossin@proton.me> | 2023-06-30 15:03:23 +0000 |
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committer | Miguel Ojeda <ojeda@kernel.org> | 2023-08-10 01:18:34 +0200 |
commit | 0b4e3b6f6b79b1add04008a6ceaaf661107e8902 (patch) | |
tree | b02ce71b84124f5f6320d35d660fa5cda46a2622 | |
parent | 35cad617df2eeef8440a38e82bb2d81ae32ca50d (diff) | |
download | linux-stable-0b4e3b6f6b79b1add04008a6ceaaf661107e8902.tar.gz linux-stable-0b4e3b6f6b79b1add04008a6ceaaf661107e8902.tar.bz2 linux-stable-0b4e3b6f6b79b1add04008a6ceaaf661107e8902.zip |
rust: types: make `Opaque` be `!Unpin`
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@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20230630150216.109789-1-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
-rw-r--r-- | rust/kernel/types.rs | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index c0b8bb1a7539..50cbd767ea9d 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -6,7 +6,7 @@ use crate::init::{self, PinInit}; use alloc::boxed::Box; use core::{ cell::UnsafeCell, - marker::PhantomData, + marker::{PhantomData, PhantomPinned}, mem::MaybeUninit, ops::{Deref, DerefMut}, ptr::NonNull, @@ -206,17 +206,26 @@ impl<T, F: FnOnce(T)> Drop for ScopeGuard<T, F> { /// /// 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 @@ impl<T> Opaque<T> { /// 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`. |