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
+    /// // 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