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authorBenno Lossin <benno.lossin@proton.me>2023-06-30 15:03:23 +0000
committerMiguel Ojeda <ojeda@kernel.org>2023-08-10 01:18:34 +0200
commit0b4e3b6f6b79b1add04008a6ceaaf661107e8902 (patch)
treeb02ce71b84124f5f6320d35d660fa5cda46a2622
parent35cad617df2eeef8440a38e82bb2d81ae32ca50d (diff)
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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.rs19
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`.