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[PATCH v10 3/5] rust: Add missing SAFETY documentation for ARef example

Oliver Mangold posted 5 patches 9 months, 1 week ago
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[PATCH v10 3/5] rust: Add missing SAFETY documentation for ARef example
Posted by Oliver Mangold 9 months, 1 week ago 
SAFETY comment in rustdoc example was just 'TODO'. Fixed.

Signed-off-by: Oliver Mangold <oliver.mangold@pm.me>
---
 rust/kernel/types.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index d7fa8934c545f46a646ca900ab8957a04b0ad34d..33d2b4e4a87b991c6d934f4e8d2c6c71a15b1bcb 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -498,7 +498,9 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
     ///
     /// struct Empty {}
     ///
-    /// # // SAFETY: TODO.
+    /// // SAFETY: The `RefCounted` implementation for `Empty` does not count references
+    /// // and never frees the underlying object. Thus we can act as having a
+    /// // refcount on the object that we pass to the newly created `ARef`.
     /// unsafe impl RefCounted for Empty {
     ///     fn inc_ref(&self) {}
     ///     unsafe fn dec_ref(_obj: NonNull<Self>) {}
@@ -506,7 +508,7 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
     ///
     /// let mut data = Empty {};
     /// let ptr = NonNull::<Empty>::new(&mut data).unwrap();
-    /// # // SAFETY: TODO.
+    /// // SAFETY: We keep `data` around longer than the `ARef`.
     /// let data_ref: ARef<Empty> = unsafe { ARef::from_raw(ptr) };
     /// let raw_ptr: NonNull<Empty> = ARef::into_raw(data_ref);
     ///

-- 
2.49.0
Re: [PATCH v10 3/5] rust: Add missing SAFETY documentation for ARef example
Posted by Andreas Hindborg 9 months, 1 week ago 
"Oliver Mangold" <oliver.mangold@pm.me> writes:

> SAFETY comment in rustdoc example was just 'TODO'. Fixed.
>
> Signed-off-by: Oliver Mangold <oliver.mangold@pm.me>
> ---
>  rust/kernel/types.rs | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> index d7fa8934c545f46a646ca900ab8957a04b0ad34d..33d2b4e4a87b991c6d934f4e8d2c6c71a15b1bcb 100644
> --- a/rust/kernel/types.rs
> +++ b/rust/kernel/types.rs
> @@ -498,7 +498,9 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
>      ///
>      /// struct Empty {}
>      ///
> -    /// # // SAFETY: TODO.
> +    /// // SAFETY: The `RefCounted` implementation for `Empty` does not count references
> +    /// // and never frees the underlying object. Thus we can act as having a
> +    /// // refcount on the object that we pass to the newly created `ARef`.
>      /// unsafe impl RefCounted for Empty {
>      ///     fn inc_ref(&self) {}
>      ///     unsafe fn dec_ref(_obj: NonNull<Self>) {}
> @@ -506,7 +508,7 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
>      ///
>      /// let mut data = Empty {};
>      /// let ptr = NonNull::<Empty>::new(&mut data).unwrap();
> -    /// # // SAFETY: TODO.
> +    /// // SAFETY: We keep `data` around longer than the `ARef`.

I still think this applies:

>> How about:
>> 
>>   The `RefCounted` implementation for `Empty` does not count references
>>   and never frees the underlying object. Thus we can act as having a
>>   refcount on the object that we pass to the newly created `ARef`.
>> 

>      /// let data_ref: ARef<Empty> = unsafe { ARef::from_raw(ptr) };
>      /// let raw_ptr: NonNull<Empty> = ARef::into_raw(data_ref);
>      ///


Best regards,
Andreas Hindborg
Re: [PATCH v10 3/5] rust: Add missing SAFETY documentation for ARef example
Posted by Oliver Mangold 9 months, 1 week ago 
On 250502 1241, Andreas Hindborg wrote:
> >
> > diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> > index d7fa8934c545f46a646ca900ab8957a04b0ad34d..33d2b4e4a87b991c6d934f4e8d2c6c71a15b1bcb 100644
> > --- a/rust/kernel/types.rs
> > +++ b/rust/kernel/types.rs
> > @@ -498,7 +498,9 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
> >      ///
> >      /// struct Empty {}
> >      ///
> > -    /// # // SAFETY: TODO.
> > +    /// // SAFETY: The `RefCounted` implementation for `Empty` does not count references
> > +    /// // and never frees the underlying object. Thus we can act as having a
> > +    /// // refcount on the object that we pass to the newly created `ARef`.
> >      /// unsafe impl RefCounted for Empty {
> >      ///     fn inc_ref(&self) {}
> >      ///     unsafe fn dec_ref(_obj: NonNull<Self>) {}
> > @@ -506,7 +508,7 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
> >      ///
> >      /// let mut data = Empty {};
> >      /// let ptr = NonNull::<Empty>::new(&mut data).unwrap();
> > -    /// # // SAFETY: TODO.
> > +    /// // SAFETY: We keep `data` around longer than the `ARef`.
> 
> I still think this applies:
> 
> >> How about:
> >>
> >>   The `RefCounted` implementation for `Empty` does not count references
> >>   and never frees the underlying object. Thus we can act as having a
> >>   refcount on the object that we pass to the newly created `ARef`.
> >>

Hi Andreas,

I agree. Sorry, I just messed up the fix. Your wording landed in the
previous to-be-fixed unsafe comment, as you can see.

Happens when you are too much in a hurry and didn't touch the patch for
too long :/

I will fix it in the next version.

Best,

Oliver
Re: [PATCH v10 3/5] rust: Add missing SAFETY documentation for ARef example
Posted by Andreas Hindborg 9 months, 1 week ago 
"Oliver Mangold" <oliver.mangold@pm.me> writes:

> On 250502 1241, Andreas Hindborg wrote:
>> >
>> > diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
>> > index d7fa8934c545f46a646ca900ab8957a04b0ad34d..33d2b4e4a87b991c6d934f4e8d2c6c71a15b1bcb 100644
>> > --- a/rust/kernel/types.rs
>> > +++ b/rust/kernel/types.rs
>> > @@ -498,7 +498,9 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
>> >      ///
>> >      /// struct Empty {}
>> >      ///
>> > -    /// # // SAFETY: TODO.
>> > +    /// // SAFETY: The `RefCounted` implementation for `Empty` does not count references
>> > +    /// // and never frees the underlying object. Thus we can act as having a
>> > +    /// // refcount on the object that we pass to the newly created `ARef`.
>> >      /// unsafe impl RefCounted for Empty {
>> >      ///     fn inc_ref(&self) {}
>> >      ///     unsafe fn dec_ref(_obj: NonNull<Self>) {}
>> > @@ -506,7 +508,7 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
>> >      ///
>> >      /// let mut data = Empty {};
>> >      /// let ptr = NonNull::<Empty>::new(&mut data).unwrap();
>> > -    /// # // SAFETY: TODO.
>> > +    /// // SAFETY: We keep `data` around longer than the `ARef`.
>>
>> I still think this applies:
>>
>> >> How about:
>> >>
>> >>   The `RefCounted` implementation for `Empty` does not count references
>> >>   and never frees the underlying object. Thus we can act as having a
>> >>   refcount on the object that we pass to the newly created `ARef`.
>> >>
>
> Hi Andreas,
>
> I agree. Sorry, I just messed up the fix. Your wording landed in the
> previous to-be-fixed unsafe comment, as you can see.
>
> Happens when you are too much in a hurry and didn't touch the patch for
> too long :/
>
> I will fix it in the next version.

Cool! Also check my response to v9: https://lore.kernel.org/all/87cycrz1pa.fsf@kernel.org


Best regards,
Andreas Hindborg

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