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rust: kernel: change ForeignOwnable pointer to mut

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It is slightly more convenient to operate on mut pointers, and this also
properly conveys the desired ownership semantics of the trait.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241120-borrow-mut-v6-4-80dbadd00951@gmail.com
[ Reworded title slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Tamir Duberstein 2024-11-20 06:46:03 -05:00 committed by Miguel Ojeda
parent 5d385a356f
commit 14686571a9
4 changed files with 21 additions and 21 deletions
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16
rust/kernel/alloc/kbox.rs
View File

@ -355,17 +355,17 @@ where
{
type Borrowed<'a> = &'a T;
fn into_foreign(self) -> *const crate::ffi::c_void {
fn into_foreign(self) -> *mut crate::ffi::c_void {
Box::into_raw(self).cast()
}
unsafe fn from_foreign(ptr: *const crate::ffi::c_void) -> Self {
unsafe fn from_foreign(ptr: *mut crate::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 crate::ffi::c_void) -> &'a T {
unsafe fn borrow<'a>(ptr: *mut crate::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() }
@ -378,18 +378,18 @@ where
{
type Borrowed<'a> = Pin<&'a T>;
fn into_foreign(self) -> *const crate::ffi::c_void {
fn into_foreign(self) -> *mut crate::ffi::c_void {
// SAFETY: We are still treating the box as pinned.
Box::into_raw(unsafe { Pin::into_inner_unchecked(self) }).cast()
}
unsafe fn from_foreign(ptr: *const crate::ffi::c_void) -> Self {
unsafe fn from_foreign(ptr: *mut crate::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 crate::ffi::c_void) -> Pin<&'a T> {
unsafe fn borrow<'a>(ptr: *mut crate::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

2
rust/kernel/miscdevice.rs
View File

@ -189,7 +189,7 @@ unsafe extern "C" fn fops_open<T: MiscDevice>(
};
// SAFETY: The open call of a file owns the private data.
unsafe { (*file).private_data = ptr.into_foreign().cast_mut() };
unsafe { (*file).private_data = ptr.into_foreign() };
0
}

10
rust/kernel/sync/arc.rs
View File

@ -345,24 +345,24 @@ impl<T: ?Sized> Arc<T> {
impl<T: 'static> ForeignOwnable for Arc<T> {
type Borrowed<'a> = ArcBorrow<'a, T>;
fn into_foreign(self) -> *const crate::ffi::c_void {
fn into_foreign(self) -> *mut crate::ffi::c_void {
ManuallyDrop::new(self).ptr.as_ptr().cast()
}
unsafe fn borrow<'a>(ptr: *const crate::ffi::c_void) -> ArcBorrow<'a, T> {
unsafe fn borrow<'a>(ptr: *mut crate::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 crate::ffi::c_void) -> Self {
unsafe fn from_foreign(ptr: *mut crate::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

14
rust/kernel/types.rs
View File

@ -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 crate::ffi::c_void;
fn into_foreign(self) -> *mut crate::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 crate::ffi::c_void) -> Self::Borrowed<'a>;
unsafe fn borrow<'a>(ptr: *mut crate::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 crate::ffi::c_void) -> Self;
unsafe fn from_foreign(ptr: *mut crate::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 crate::ffi::c_void) -> Option<Self> {
unsafe fn try_from_foreign(ptr: *mut crate::ffi::c_void) -> Option<Self> {
if ptr.is_null() {
None
} else {
@ -72,13 +72,13 @@ pub trait ForeignOwnable: Sized {
impl ForeignOwnable for () {
type Borrowed<'a> = ();
fn into_foreign(self) -> *const crate::ffi::c_void {
fn into_foreign(self) -> *mut crate::ffi::c_void {
core::ptr::NonNull::dangling().as_ptr()
}
unsafe fn borrow<'a>(_: *const crate::ffi::c_void) -> Self::Borrowed<'a> {}
unsafe fn borrow<'a>(_: *mut crate::ffi::c_void) -> Self::Borrowed<'a> {}
unsafe fn from_foreign(_: *const crate::ffi::c_void) -> Self {}
unsafe fn from_foreign(_: *mut crate::ffi::c_void) -> Self {}
}
/// Runs a cleanup function/closure when dropped.