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Message-Id: <20241030-borrow-mut-v1-3-8f0ceaf78eaf@gmail.com>
Date: Wed, 30 Oct 2024 16:46:40 -0400
From: Tamir Duberstein <tamird@...il.com>
To: 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>
Cc: rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org,
Tamir Duberstein <tamird@...il.com>
Subject: [PATCH 3/5] rust: change `ForeignOwnable` pointer to mut
It is slightly more convenient to operate on mut pointers, and this also
properly conveys the desired ownership semantics of the trait.
Signed-off-by: Tamir Duberstein <tamird@...il.com>
---
rust/kernel/alloc/kbox.rs | 22 ++++++++++------------
rust/kernel/sync/arc.rs | 12 ++++++------
rust/kernel/types.rs | 14 +++++++-------
3 files changed, 23 insertions(+), 25 deletions(-)
diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index 7a5fdf7b660fb91ca2a8e5023d69d629b0d66062..de7fadeb7fdf5cf6742c2e9749e959ac5f82359e 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -355,18 +355,18 @@ impl<T: 'static, A> ForeignOwnable for Box<T, A>
{
type Borrowed<'a> = &'a T;
- fn into_foreign(self) -> *const core::ffi::c_void {
- Box::into_raw(self).cast_const().cast()
+ fn into_foreign(self) -> *mut core::ffi::c_void {
+ Box::into_raw(self).cast()
}
- unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
- let ptr = ptr.cast_mut().cast();
+ unsafe fn from_foreign(ptr: *mut core::ffi::c_void) -> Self {
+ let ptr = ptr.cast();
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
unsafe { Box::from_raw(ptr) }
}
- unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
+ unsafe fn borrow<'a>(ptr: *mut core::ffi::c_void) -> &'a T {
let ptr = ptr.cast();
// SAFETY: The safety requirements of this method ensure that the object remains alive and
// immutable for the duration of 'a.
@@ -380,21 +380,19 @@ impl<T: 'static, A> ForeignOwnable for Pin<Box<T, A>>
{
type Borrowed<'a> = Pin<&'a T>;
- fn into_foreign(self) -> *const core::ffi::c_void {
+ fn into_foreign(self) -> *mut core::ffi::c_void {
// SAFETY: We are still treating the box as pinned.
- Box::into_raw(unsafe { Pin::into_inner_unchecked(self) })
- .cast_const()
- .cast()
+ Box::into_raw(unsafe { Pin::into_inner_unchecked(self) }).cast()
}
- unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
- let ptr = ptr.cast_mut().cast();
+ unsafe fn from_foreign(ptr: *mut core::ffi::c_void) -> Self {
+ let ptr = ptr.cast();
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
unsafe { Pin::new_unchecked(Box::from_raw(ptr)) }
}
- unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> Pin<&'a T> {
+ unsafe fn borrow<'a>(ptr: *mut core::ffi::c_void) -> Pin<&'a T> {
let ptr = ptr.cast();
// SAFETY: The safety requirements for this function ensure that the object is still alive,
// so it is safe to dereference the raw pointer.
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 88e5208369e40bdeebc6f758e89f836a97790d89..26b7272424aafdd4847d9642456cab837797ac33 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -335,12 +335,12 @@ pub fn into_unique_or_drop(self) -> Option<Pin<UniqueArc<T>>> {
impl<T: 'static> ForeignOwnable for Arc<T> {
type Borrowed<'a> = ArcBorrow<'a, T>;
- fn into_foreign(self) -> *const core::ffi::c_void {
- ManuallyDrop::new(self).ptr.as_ptr().cast_const().cast()
+ fn into_foreign(self) -> *mut core::ffi::c_void {
+ ManuallyDrop::new(self).ptr.as_ptr().cast()
}
- unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> ArcBorrow<'a, T> {
- let ptr = ptr.cast_mut().cast();
+ unsafe fn borrow<'a>(ptr: *mut core::ffi::c_void) -> ArcBorrow<'a, T> {
+ let ptr = ptr.cast();
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
@@ -351,8 +351,8 @@ unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> ArcBorrow<'a, T> {
unsafe { ArcBorrow::new(inner) }
}
- unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
- let ptr = ptr.cast_mut().cast();
+ unsafe fn from_foreign(ptr: *mut core::ffi::c_void) -> Self {
+ let ptr = ptr.cast();
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index e8b7ff1387381e50d7963978e57b1d567113b035..04358375794dc5ba7bfebbe3cfc5885cff531f15 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -29,7 +29,7 @@ pub trait ForeignOwnable: Sized {
/// For example, it might be invalid, dangling or pointing to uninitialized memory. Using it in
/// any way except for [`ForeignOwnable::from_foreign`], [`ForeignOwnable::borrow`],
/// [`ForeignOwnable::try_from_foreign`] can result in undefined behavior.
- fn into_foreign(self) -> *const core::ffi::c_void;
+ fn into_foreign(self) -> *mut core::ffi::c_void;
/// Borrows a foreign-owned object.
///
@@ -37,7 +37,7 @@ pub trait ForeignOwnable: Sized {
///
/// `ptr` must have been returned by a previous call to [`ForeignOwnable::into_foreign`] for
/// which a previous matching [`ForeignOwnable::from_foreign`] hasn't been called yet.
- unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> Self::Borrowed<'a>;
+ unsafe fn borrow<'a>(ptr: *mut core::ffi::c_void) -> Self::Borrowed<'a>;
/// Converts a foreign-owned object back to a Rust-owned one.
///
@@ -47,7 +47,7 @@ pub trait ForeignOwnable: Sized {
/// which a previous matching [`ForeignOwnable::from_foreign`] hasn't been called yet.
/// Additionally, all instances (if any) of values returned by [`ForeignOwnable::borrow`] for
/// this object must have been dropped.
- unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self;
+ unsafe fn from_foreign(ptr: *mut core::ffi::c_void) -> Self;
/// Tries to convert a foreign-owned object back to a Rust-owned one.
///
@@ -58,7 +58,7 @@ pub trait ForeignOwnable: Sized {
///
/// `ptr` must either be null or satisfy the safety requirements for
/// [`ForeignOwnable::from_foreign`].
- unsafe fn try_from_foreign(ptr: *const core::ffi::c_void) -> Option<Self> {
+ unsafe fn try_from_foreign(ptr: *mut core::ffi::c_void) -> Option<Self> {
if ptr.is_null() {
None
} else {
@@ -72,13 +72,13 @@ unsafe fn try_from_foreign(ptr: *const core::ffi::c_void) -> Option<Self> {
impl ForeignOwnable for () {
type Borrowed<'a> = ();
- fn into_foreign(self) -> *const core::ffi::c_void {
+ fn into_foreign(self) -> *mut core::ffi::c_void {
core::ptr::NonNull::dangling().as_ptr()
}
- unsafe fn borrow<'a>(_: *const core::ffi::c_void) -> Self::Borrowed<'a> {}
+ unsafe fn borrow<'a>(_: *mut core::ffi::c_void) -> Self::Borrowed<'a> {}
- unsafe fn from_foreign(_: *const core::ffi::c_void) -> Self {}
+ unsafe fn from_foreign(_: *mut core::ffi::c_void) -> Self {}
}
/// Runs a cleanup function/closure when dropped.
--
2.47.0
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