[PATCH v14 3/9] rust: Add missing SAFETY documentation for `ARef` example

[Andreas Hindborg]

From: Oliver Mangold <oliver.mangold@xxxxx>

SAFETY comment in rustdoc example was just 'TODO'. Fixed.

Original patch by Oliver Mangold <oliver.mangold@xxxxx> [1].

Link: https://lore.kernel.org/r/20251117-unique-ref-v13-3-b5b243df1250@xxxxx [1]
Reviewed-by: Daniel Almeida <daniel.almeida@xxxxxxxxxxxxx>
Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
---
 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 61caddfd89619..efe16a7fdfa5d 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 owning an increment on the refcount for
+    /// // 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>) {}
@@ -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