Re: [PATCH 01/17] rust: sync: completion: add wait_for_completion_timeout()

[Alexandre Courbot]

On Sat Aug 8, 2026 at 12:11 PM JST, John Hubbard wrote:
> From: Joel Fernandes <joelagnelf@xxxxxxxxxx>
>
> A driver that runs an interrupt self-test during probe waits for the
> handler to fire. wait_for_completion() has no timeout, so a broken
> interrupt path stalls probe indefinitely. Add a timeout variant of
> wait_for_completion().
>
> Document the type invariant that Completion always holds an initialized
> struct completion, and cite it in the SAFETY comments.

That last paragraph (and the associated hunks below) are a different
thing, and should be its own patch.

<...>
>  /// Synchronization primitive to signal when a certain task has been completed.
>  ///
>  /// The [`Completion`] synchronization primitive signals when a certain task has been completed by
>  /// waking up other tasks that have been queued up to wait for the [`Completion`] to be completed.
>  ///
> +/// # Invariants
> +///
> +/// `inner` always holds an initialized `struct completion`.
> +///
>  /// # Examples
>  ///
>  /// ```
> @@ -96,7 +105,8 @@ fn as_raw(&self) -> *mut bindings::completion {
>      /// completion is permanently done, i.e. signals all current and future waiters.
>      #[inline]
>      pub fn complete_all(&self) {
> -        // SAFETY: `self.as_raw()` is a pointer to a valid `struct completion`.
> +        // SAFETY: By the type invariant, `self.as_raw()` is a pointer to an initialized
> +        // `struct completion`.
>          unsafe { bindings::complete_all(self.as_raw()) };
>      }
>  
> @@ -108,7 +118,25 @@ pub fn complete_all(&self) {
>      /// See also [`Completion::complete_all`].
>      #[inline]
>      pub fn wait_for_completion(&self) {
> -        // SAFETY: `self.as_raw()` is a pointer to a valid `struct completion`.
> +        // SAFETY: By the type invariant, `self.as_raw()` is a pointer to an initialized
> +        // `struct completion`.
>          unsafe { bindings::wait_for_completion(self.as_raw()) };
>      }

These hunks are what should be extracted, or even dropped as
`wait_for_completion_timeout` doesn't add any extra requirement for
them.