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Message-Id: <20250430-rust_unsafe_pinned-v2-2-fc8617a74024@gmail.com>
Date: Wed, 30 Apr 2025 10:36:12 +0200
From: Christian Schrefl <chrisi.schrefl@...il.com>
To: Sky <sky@...9.dev>, Miguel Ojeda <ojeda@...nel.org>,
Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>,
Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>,
Gerald Wisböck <gerald.wisboeck@...ther.ink>
Cc: linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org,
Christian Schrefl <chrisi.schrefl@...il.com>
Subject: [PATCH v2 2/3] rust: implement `Wrapper<T>` for `Opaque<T>`
Moves the implementation for `pin-init` from an associated function
to the trait function of the `Wrapper` trait and extends the
implementation to support pin-initializers with error types.
This allows to declare functions that are generic over `Wrapper`
types.
Adds a use for the `Wrapper` trait in `revocable.rs`, to use the new
`pin-init` function. This is currently the only usage in the kernel.
Reviewed-by: Gerald Wisböck <gerald.wisboeck@...ther.ink>
Signed-off-by: Christian Schrefl <chrisi.schrefl@...il.com>
---
rust/kernel/revocable.rs | 2 ++
rust/kernel/types.rs | 25 +++++++++++++------------
2 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/rust/kernel/revocable.rs b/rust/kernel/revocable.rs
index 1e5a9d25c21b279b01f90b02997492aa4880d84f..4db68ea2207ebafcc09d082fdc1e281f31846a38 100644
--- a/rust/kernel/revocable.rs
+++ b/rust/kernel/revocable.rs
@@ -5,6 +5,8 @@
//! The [`Revocable`] type wraps other types and allows access to them to be revoked. The existence
//! of a [`RevocableGuard`] ensures that objects remain valid.
+use pin_init::Wrapper;
+
use crate::{bindings, prelude::*, sync::rcu, types::Opaque};
use core::{
marker::PhantomData,
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 705f420fdfbc4a576de1c4546578f2f04cdf615e..f06e8720e012102e5c41e79fd97b0607e927d71c 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -9,7 +9,7 @@
ops::{Deref, DerefMut},
ptr::NonNull,
};
-use pin_init::{PinInit, Zeroable};
+use pin_init::{PinInit, Wrapper, Zeroable};
/// Used to transfer ownership to and from foreign (non-Rust) languages.
///
@@ -332,17 +332,6 @@ pub const fn uninit() -> Self {
}
}
- /// Create an opaque pin-initializer from the given pin-initializer.
- pub fn pin_init(slot: impl PinInit<T>) -> impl PinInit<Self> {
- Self::ffi_init(|ptr: *mut T| {
- // SAFETY:
- // - `ptr` is a valid pointer to uninitialized memory,
- // - `slot` is not accessed on error; the call is infallible,
- // - `slot` is pinned in memory.
- let _ = unsafe { PinInit::<T>::__pinned_init(slot, ptr) };
- })
- }
-
/// Creates a pin-initializer from the given initializer closure.
///
/// The returned initializer calls the given closure with the pointer to the inner `T` of this
@@ -393,6 +382,18 @@ pub const fn raw_get(this: *const Self) -> *mut T {
UnsafeCell::raw_get(this.cast::<UnsafeCell<MaybeUninit<T>>>()).cast::<T>()
}
}
+impl<T> Wrapper<T> for Opaque<T> {
+ /// Create an opaque pin-initializer from the given pin-initializer.
+ fn pin_init<E>(slot: impl PinInit<T, E>) -> impl PinInit<Self, E> {
+ Self::try_ffi_init(|ptr: *mut T| {
+ // SAFETY:
+ // - `ptr` is a valid pointer to uninitialized memory,
+ // - `slot` is not accessed on error; the call is infallible,
+ // - `slot` is pinned in memory.
+ unsafe { PinInit::<T, E>::__pinned_init(slot, ptr) }
+ })
+ }
+}
/// Types that are _always_ reference counted.
///
--
2.49.0
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