[PATCH v2] rust: workqueue: fix SAFETY comment Arc refs in Pin<KBox<T>>

[PATCH v2] rust: workqueue: fix SAFETY comment Arc refs in Pin<KBox<T>>

[Sagar Taunk]

The `WorkItemPointer` implementation for `Pin<KBox<T>>` contained SAFETY
comments that incorrectly referenced `Arc::into_raw` instead of
`KBox::into_raw`. This implementation uses `KBox`, not `Arc`, so update
the comments to accurately reflect the actual ownership transfer.

Fixes: 8373147ce496 ("rust: treewide: switch to our kernel `Box` type")
Cc: stable@vger.kernel.org
Suggested-by: Onur Özkan <contact@onurozkan.dev>
Link: https://github.com/Rust-for-Linux/linux/issues/1233
Signed-off-by: Sagar Taunk <sagartaunk2@gmail.com>
---
 rust/kernel/workqueue.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 7e253b6f299c..74c59f2b1c09 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -890,9 +890,10 @@ unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Pin<KBox<T>>
     unsafe extern "C" fn run(ptr: *mut bindings::work_struct) {
         // The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
         let ptr = ptr.cast::<Work<T, ID>>();
-        // SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`.
+        // SAFETY: This computes the pointer that `__enqueue` got from `KBox::into_raw`.
         let ptr = unsafe { T::work_container_of(ptr) };
-        // SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership.
+        // SAFETY: This pointer comes from `KBox::into_raw` and we have been given back ownership,
+        // as the workqueue guarantees `run` is called exactly once.
         let boxed = unsafe { KBox::from_raw(ptr) };
         // SAFETY: The box was already pinned when it was enqueued.
         let pinned = unsafe { Pin::new_unchecked(boxed) };
-- 
2.54.0

Re: [PATCH v2] rust: workqueue: fix SAFETY comment Arc refs in Pin<KBox<T>>

[Miguel Ojeda]

On Sun, Apr 26, 2026 at 7:53 PM Sagar Taunk <sagartaunk2@gmail.com> wrote:
>
> The `WorkItemPointer` implementation for `Pin<KBox<T>>` contained SAFETY
> comments that incorrectly referenced `Arc::into_raw` instead of
> `KBox::into_raw`. This implementation uses `KBox`, not `Arc`, so update
> the comments to accurately reflect the actual ownership transfer.
>
> Fixes: 8373147ce496 ("rust: treewide: switch to our kernel `Box` type")
> Cc: stable@vger.kernel.org
> Suggested-by: Onur Özkan <contact@onurozkan.dev>
> Link: https://github.com/Rust-for-Linux/linux/issues/1233
> Signed-off-by: Sagar Taunk <sagartaunk2@gmail.com>

I should have mentioned that, in the case of making it a fix, one
usually uses Reported-by: and Closes: instead of Suggested-by: and
Link:

No need for v3 for that I would say -- the maintainers may fix this on apply :)

Thanks!

Cheers,
Miguel

Re: [PATCH v2] rust: workqueue: fix SAFETY comment Arc refs in Pin<KBox<T>>

[Sagar Taunk]

Thanks for the feedback! I'll use Reported-by and Closes next time.

Cheers,
Sagar