[PATCH v1] rust: kernel: types: Add `ARef::into_raw`

[PATCH v1] rust: kernel: types: Add `ARef::into_raw`

[Vincenzo Palazzo]

Add the function `into_raw` to `ARef<T>`. This method
can be used to turn an `ARef` into a raw pointer.

Link: https://github.com/Rust-for-Linux/linux/issues/1044
Co-developed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
---
 rust/kernel/types.rs | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index aa77bad9bce4..b2a243bb810e 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -366,6 +366,38 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
             _p: PhantomData,
         }
     }
+
+    /// Deconstructs a [`ARef`] object into a raw pointer.
+    ///
+    /// It can be reconstructed once via [`ARef::from_raw`].
+    ///
+    /// Note: This function does not decrement the reference count.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::ptr::NonNull;
+    /// use kernel::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: *mut Empty = ARef::into_raw(data_ref);
+    ///
+    /// assert_eq!(ptr.as_ptr(), raw_ptr);
+    /// ```
+    pub fn into_raw(obj: Self) -> *mut T {
+        let ptr = obj.ptr.as_ptr();
+        core::mem::forget(obj);
+        ptr
+    }
 }
 
 impl<T: AlwaysRefCounted> Clone for ARef<T> {
-- 
2.44.0

Re: [PATCH v1] rust: kernel: types: Add `ARef::into_raw`

[Miguel Ojeda]

Hi Vincenzo,

Thanks for sending this!

(This is a resend -- apparently vger has had some delays for the last
~14 hours or so.)

On Mon, Mar 25, 2024 at 12:05 PM Vincenzo Palazzo
<vincenzopalazzodev@gmail.com> wrote:
>
> Add the function `into_raw` to `ARef<T>`. This method
> can be used to turn an `ARef` into a raw pointer.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/1044
> Co-developed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
> Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
> Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

Given what you wrote here, I think you intended to give the primary
authorship to Kartik, right? If that is the case, that would require a
different ordering of these lines (like the last example at
https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by):

    Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
    Co-developed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
    Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

In addition, the commit should be properly attributed to Kartik in
Git, which means you will automatically get the `From: Kartik ...`
line too that you see in the example of the documentation I linked
above.

However, from what I can tell, you didn't modify the commit from
Kartik at all. If that is correct, then the `Co-developed-by` should
not be there (https://docs.kernel.org/process/submitting-patches.html#developer-s-certificate-of-origin-1-1
has the details).

Finally, for v2, could you please To/Cc the rest of the
maintainers/reviewers? You can use `scripts/get_maintainer.pl` for
that, or the couple commands at
https://rust-for-linux.com/contributing#submitting-patches.

Thanks!

Cheers,
Miguel

Re: [PATCH v1] rust: kernel: types: Add `ARef::into_raw`

[Vincenzo Palazzo]

> Hi Vincenzo,
>
> Thanks for sending this!
>
> (This is a resend -- apparently vger has had some delays for the last
> ~14 hours or so.)

Yeah sorry about the double posting on the ML, but looks like that now
all is fine.

Thanks

   Vincent.

>
> On Mon, Mar 25, 2024 at 12:05 PM Vincenzo Palazzo
> <vincenzopalazzodev@gmail.com> wrote:
> >
> > Add the function `into_raw` to `ARef<T>`. This method
> > can be used to turn an `ARef` into a raw pointer.
> >
> > Link: https://github.com/Rust-for-Linux/linux/issues/1044
> > Co-developed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
> > Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
> > Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
>
> Given what you wrote here, I think you intended to give the primary
> authorship to Kartik, right? If that is the case, that would require a
> different ordering of these lines (like the last example at
> https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by):
>
>     Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
>     Co-developed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
>     Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
>
> In addition, the commit should be properly attributed to Kartik in
> Git, which means you will automatically get the `From: Kartik ...`
> line too that you see in the example of the documentation I linked
> above.
>
> However, from what I can tell, you didn't modify the commit from
> Kartik at all. If that is correct, then the `Co-developed-by` should
> not be there (https://docs.kernel.org/process/submitting-patches.html#developer-s-certificate-of-origin-1-1
> has the details).
>
> Finally, for v2, could you please To/Cc the rest of the
> maintainers/reviewers? You can use `scripts/get_maintainer.pl` for
> that, or the couple commands at
> https://rust-for-linux.com/contributing#submitting-patches.
>
> Thanks!
>
> Cheers,
> Miguel

[PATCH v1] rust: kernel: types: Add `ARef::into_raw`

[Vincenzo Palazzo]

Add the function `into_raw` to `ARef<T>`. This method
can be used to turn an `ARef` into a raw pointer.

Link: https://github.com/Rust-for-Linux/linux/issues/1044
Co-developed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
---
 rust/kernel/types.rs | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index aa77bad9bce4..b2a243bb810e 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -366,6 +366,38 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
             _p: PhantomData,
         }
     }
+
+    /// Deconstructs a [`ARef`] object into a raw pointer.
+    ///
+    /// It can be reconstructed once via [`ARef::from_raw`].
+    ///
+    /// Note: This function does not decrement the reference count.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::ptr::NonNull;
+    /// use kernel::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: *mut Empty = ARef::into_raw(data_ref);
+    ///
+    /// assert_eq!(ptr.as_ptr(), raw_ptr);
+    /// ```
+    pub fn into_raw(obj: Self) -> *mut T {
+        let ptr = obj.ptr.as_ptr();
+        core::mem::forget(obj);
+        ptr
+    }
 }
 
 impl<T: AlwaysRefCounted> Clone for ARef<T> {
-- 
2.44.0