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Message-Id: <20241104-borrow-mut-v2-4-de650678648d@gmail.com>
Date: Mon, 04 Nov 2024 17:20:30 -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 v2 4/6] 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>
Reviewed-by: Andreas Hindborg <a.hindborg@...nel.org>
Reviewed-by: Alice Ryhl <aliceryhl@...gle.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 b6b6723098b6b30743bf38c97aab0e701a5a1be4..99d0fc0148bb8779e5a769a6e74291ef8101bf77 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -355,17 +355,17 @@ 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 {
+ unsafe fn from_foreign(ptr: *mut core::ffi::c_void) -> Self {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
- unsafe { Box::from_raw(ptr.cast_mut().cast()) }
+ unsafe { Box::from_raw(ptr.cast()) }
}
- unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
+ unsafe fn borrow<'a>(ptr: *mut core::ffi::c_void) -> &'a T {
// SAFETY: The safety requirements of this method ensure that the object remains alive and
// immutable for the duration of 'a.
unsafe { &*ptr.cast() }
@@ -378,20 +378,18 @@ 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 {
+ unsafe fn from_foreign(ptr: *mut core::ffi::c_void) -> Self {
// 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.cast_mut().cast())) }
+ unsafe { Pin::new_unchecked(Box::from_raw(ptr.cast())) }
}
- 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> {
// SAFETY: The safety requirements for this function ensure that the object is still alive,
// so it is safe to dereference the raw pointer.
// The safety requirements of `from_foreign` also ensure that the object remains alive for
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 9adea755a5ad1a7b03f7fc30a7abc76c1f966c6c..10819dc28b64038b9abc55b01c069826d1e5befa 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -333,24 +333,24 @@ 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> {
+ unsafe fn borrow<'a>(ptr: *mut core::ffi::c_void) -> ArcBorrow<'a, T> {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
- let inner = unsafe { NonNull::new_unchecked(ptr.cast_mut().cast::<ArcInner<T>>()) };
+ let inner = unsafe { NonNull::new_unchecked(ptr.cast::<ArcInner<T>>()) };
// SAFETY: The safety requirements of `from_foreign` ensure that the object remains alive
// for the lifetime of the returned value.
unsafe { ArcBorrow::new(inner) }
}
- unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
+ unsafe fn from_foreign(ptr: *mut core::ffi::c_void) -> Self {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
- let inner = unsafe { NonNull::new_unchecked(ptr.cast_mut().cast::<ArcInner<T>>()) };
+ let inner = unsafe { NonNull::new_unchecked(ptr.cast::<ArcInner<T>>()) };
// SAFETY: By the safety requirement of this function, we know that `ptr` came from
// a previous call to `Arc::into_foreign`, which guarantees that `ptr` is valid and
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 364dd2dc438eb7d1c4d0a4525bf2305a42297b2b..59e71bd158713bb8e12cac95e134f57a277c1b49 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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