Re: [PATCH v13 3/4] rust: Add missing SAFETY documentation for `ARef` example

[Andreas Hindborg <a.hindborg@kernel.org>]

Daniel Almeida <daniel.almeida@collabora.com> writes:

>> On 17 Nov 2025, at 07:08, Oliver Mangold <oliver.mangold@pm.me> wrote:
>> 
>> SAFETY comment in rustdoc example was just 'TODO'. Fixed.
>> 
>> Signed-off-by: Oliver Mangold <oliver.mangold@pm.me>
>> Co-developed-by: Andreas Hindborg <a.hindborg@kernel.org>
>> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
>> ---
>> rust/kernel/sync/aref.rs | 10 ++++++----
>> 1 file changed, 6 insertions(+), 4 deletions(-)
>> 
>> diff --git a/rust/kernel/sync/aref.rs b/rust/kernel/sync/aref.rs
>> index 4226119d5ac9..937dcf6ed5de 100644
>> --- a/rust/kernel/sync/aref.rs
>> +++ b/rust/kernel/sync/aref.rs
>> @@ -129,12 +129,14 @@ pub unsafe fn from_raw(ptr: NonNull<T>) -> Self {
>>     /// # Examples
>>     ///
>>     /// ```
>> -    /// use core::ptr::NonNull;
>> -    /// use kernel::sync::aref::{ARef, RefCounted};
>> +    /// # use core::ptr::NonNull;
>> +    /// # use kernel::sync::aref::{ARef, RefCounted};
>>     ///
>>     /// 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
>
> nit: perhaps saying “an increment on the refcount” is clearer?

OK


    /// // SAFETY: The `RefCounted` implementation for `Empty` does not count references and never
    /// // frees the underlying object. Thus we can act as owning an increment on the refcount for
    /// // the object that we pass to the newly created `ARef`.

>
>> +    /// // that we pass to the newly created `ARef`.
>>     /// unsafe impl RefCounted for Empty {
>>     ///     fn inc_ref(&self) {}
>>     ///     unsafe fn dec_ref(_obj: NonNull<Self>) {}
>> @@ -142,7 +144,7 @@ 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);
>>     ///
>> 
>> -- 
>> 2.51.2
>> 
>> 
>> 
>
> Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>

Thanks.


Best regards,
Andreas Hindborg