rust/kernel/types.rs | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-)
From: Kartik Prajapati <kartikprajapati987@gmail.com>
Add a method for `ARef` that is analogous to `Arc::into_raw`. It is the
inverse operation of `ARef::from_raw`, and allows you to convert the
`ARef` back into a raw pointer while retaining ownership of the
refcount.
This new function will be used by [1] for converting the type in an
`ARef` using `ARef::from_raw(ARef::into_raw(me).cast())`. The author has
also needed the same function for other use-cases in the past, but [1]
is the first to go upstream.
This was implemented independently by Kartik and Alice. The two versions
were merged by Alice, so all mistakes are Alice's.
Link: https://lore.kernel.org/r/20240801-vma-v3-1-db6c1c0afda9@google.com [1]
Closes: https://github.com/Rust-for-Linux/linux/issues/1044
Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Sending a v2 that is merged with [1]. I didn't realize that I was
duplicating work, sorry! I'll update the author information to list
Kartik as the primary author. I kept my function body so that it returns
NonNull to mirror the type used by `ARef::from_raw`.
This change was previously included in
https://lore.kernel.org/all/20240801-vma-v3-1-db6c1c0afda9@google.com/
but is being split out in its own commit at Danilo's suggestion.
Link: https://github.com/Rust-for-Linux/linux/pull/1056 [1]
---
Changes in v2:
- Add example from [1], and fix the imports in the example so it compiles.
- Update author information to reflect merge with [1].
- Link to v1: https://lore.kernel.org/r/20240801-aref-into-raw-v1-1-33401e2fbac8@google.com
---
rust/kernel/types.rs | 31 ++++++++++++++++++++++++++++++-
1 file changed, 30 insertions(+), 1 deletion(-)
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index ee7dd1f963ef..9e7ca066355c 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -7,7 +7,7 @@
use core::{
cell::UnsafeCell,
marker::{PhantomData, PhantomPinned},
- mem::MaybeUninit,
+ mem::{ManuallyDrop, MaybeUninit},
ops::{Deref, DerefMut},
pin::Pin,
ptr::NonNull,
@@ -396,6 +396,35 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
_p: PhantomData,
}
}
+
+ /// Consumes the `ARef`, returning a raw pointer.
+ ///
+ /// This function does not change the refcount. After calling this function, the caller is
+ /// responsible for the refcount previously managed by the `ARef`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use core::ptr::NonNull;
+ /// use kernel::types::{ARef, AlwaysRefCounted};
+ ///
+ /// struct Empty {}
+ ///
+ /// unsafe impl AlwaysRefCounted for Empty {
+ /// fn inc_ref(&self) {}
+ /// unsafe fn dec_ref(_obj: NonNull<Self>) {}
+ /// }
+ ///
+ /// let mut data = Empty {};
+ /// let ptr = NonNull::<Empty>::new(&mut data as *mut _).unwrap();
+ /// let data_ref: ARef<Empty> = unsafe { ARef::from_raw(ptr) };
+ /// let raw_ptr: NonNull<Empty> = ARef::into_raw(data_ref);
+ ///
+ /// assert_eq!(ptr, raw_ptr);
+ /// ```
+ pub fn into_raw(me: Self) -> NonNull<T> {
+ ManuallyDrop::new(me).ptr
+ }
}
impl<T: AlwaysRefCounted> Clone for ARef<T> {
---
base-commit: e26fa546042add70944d018b930530d16b3cf626
change-id: 20240801-aref-into-raw-e0518131442f
Best regards,
--
Alice Ryhl <aliceryhl@google.com>On Wed, Aug 21, 2024 at 9:59 PM Alice Ryhl <aliceryhl@google.com> wrote:
>
> From: Kartik Prajapati <kartikprajapati987@gmail.com>
>
> Add a method for `ARef` that is analogous to `Arc::into_raw`. It is the
> inverse operation of `ARef::from_raw`, and allows you to convert the
> `ARef` back into a raw pointer while retaining ownership of the
> refcount.
>
> This new function will be used by [1] for converting the type in an
> `ARef` using `ARef::from_raw(ARef::into_raw(me).cast())`. The author has
> also needed the same function for other use-cases in the past, but [1]
> is the first to go upstream.
>
> This was implemented independently by Kartik and Alice. The two versions
> were merged by Alice, so all mistakes are Alice's.
>
> Link: https://lore.kernel.org/r/20240801-vma-v3-1-db6c1c0afda9@google.com [1]
> Closes: https://github.com/Rust-for-Linux/linux/issues/1044
> Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
> Co-developed-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Applied to `rust-next` -- thanks everyone!
[ Reworded to correct the author reference and changed tag to Link
since it is not a bug. - Miguel ]
Cheers,
Miguel
On 21.08.24 21:58, Alice Ryhl wrote: > From: Kartik Prajapati <kartikprajapati987@gmail.com> > > Add a method for `ARef` that is analogous to `Arc::into_raw`. It is the > inverse operation of `ARef::from_raw`, and allows you to convert the > `ARef` back into a raw pointer while retaining ownership of the > refcount. > > This new function will be used by [1] for converting the type in an > `ARef` using `ARef::from_raw(ARef::into_raw(me).cast())`. The author has > also needed the same function for other use-cases in the past, but [1] > is the first to go upstream. > > This was implemented independently by Kartik and Alice. The two versions > were merged by Alice, so all mistakes are Alice's. > > Link: https://lore.kernel.org/r/20240801-vma-v3-1-db6c1c0afda9@google.com [1] > Closes: https://github.com/Rust-for-Linux/linux/issues/1044 > Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com> > Co-developed-by: Alice Ryhl <aliceryhl@google.com> > Signed-off-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> --- Cheers, Benno
On Wed, Aug 21, 2024 at 9:59 PM Alice Ryhl <aliceryhl@google.com> wrote:
>
> From: Kartik Prajapati <kartikprajapati987@gmail.com>
>
> Add a method for `ARef` that is analogous to `Arc::into_raw`. It is the
> inverse operation of `ARef::from_raw`, and allows you to convert the
> `ARef` back into a raw pointer while retaining ownership of the
> refcount.
>
> This new function will be used by [1] for converting the type in an
> `ARef` using `ARef::from_raw(ARef::into_raw(me).cast())`. The author has
Oh, this should refer to me, oops.
> also needed the same function for other use-cases in the past, but [1]
> is the first to go upstream.
>
> This was implemented independently by Kartik and Alice. The two versions
> were merged by Alice, so all mistakes are Alice's.
>
> Link: https://lore.kernel.org/r/20240801-vma-v3-1-db6c1c0afda9@google.com [1]
> Closes: https://github.com/Rust-for-Linux/linux/issues/1044
> Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
> Co-developed-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> ---
> Sending a v2 that is merged with [1]. I didn't realize that I was
> duplicating work, sorry! I'll update the author information to list
> Kartik as the primary author. I kept my function body so that it returns
> NonNull to mirror the type used by `ARef::from_raw`.
>
> This change was previously included in
> https://lore.kernel.org/all/20240801-vma-v3-1-db6c1c0afda9@google.com/
> but is being split out in its own commit at Danilo's suggestion.
>
> Link: https://github.com/Rust-for-Linux/linux/pull/1056 [1]
> ---
> Changes in v2:
> - Add example from [1], and fix the imports in the example so it compiles.
> - Update author information to reflect merge with [1].
> - Link to v1: https://lore.kernel.org/r/20240801-aref-into-raw-v1-1-33401e2fbac8@google.com
> ---
> rust/kernel/types.rs | 31 ++++++++++++++++++++++++++++++-
> 1 file changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> index ee7dd1f963ef..9e7ca066355c 100644
> --- a/rust/kernel/types.rs
> +++ b/rust/kernel/types.rs
> @@ -7,7 +7,7 @@
> use core::{
> cell::UnsafeCell,
> marker::{PhantomData, PhantomPinned},
> - mem::MaybeUninit,
> + mem::{ManuallyDrop, MaybeUninit},
> ops::{Deref, DerefMut},
> pin::Pin,
> ptr::NonNull,
> @@ -396,6 +396,35 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
> _p: PhantomData,
> }
> }
> +
> + /// Consumes the `ARef`, returning a raw pointer.
> + ///
> + /// This function does not change the refcount. After calling this function, the caller is
> + /// responsible for the refcount previously managed by the `ARef`.
> + ///
> + /// # Examples
> + ///
> + /// ```
> + /// use core::ptr::NonNull;
> + /// use kernel::types::{ARef, AlwaysRefCounted};
> + ///
> + /// struct Empty {}
> + ///
> + /// unsafe impl AlwaysRefCounted for Empty {
> + /// fn inc_ref(&self) {}
> + /// unsafe fn dec_ref(_obj: NonNull<Self>) {}
> + /// }
> + ///
> + /// let mut data = Empty {};
> + /// let ptr = NonNull::<Empty>::new(&mut data as *mut _).unwrap();
> + /// let data_ref: ARef<Empty> = unsafe { ARef::from_raw(ptr) };
> + /// let raw_ptr: NonNull<Empty> = ARef::into_raw(data_ref);
> + ///
> + /// assert_eq!(ptr, raw_ptr);
> + /// ```
> + pub fn into_raw(me: Self) -> NonNull<T> {
> + ManuallyDrop::new(me).ptr
> + }
> }
>
> impl<T: AlwaysRefCounted> Clone for ARef<T> {
>
> ---
> base-commit: e26fa546042add70944d018b930530d16b3cf626
> change-id: 20240801-aref-into-raw-e0518131442f
>
> Best regards,
> --
> Alice Ryhl <aliceryhl@google.com>
>
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