Re: [PATCH v2 3/4] rust: devres: get rid of Devres' inner Arc

[Boqun Feng]

On Tue, Jun 24, 2025 at 06:20:41PM +0200, Danilo Krummrich wrote:
> On Tue, Jun 24, 2025 at 06:15:43PM +0200, Danilo Krummrich wrote:
> > Oh, so you meant adding this to the safety comment. Yes, that makes sense. Maybe
> > ScopeGuard works too, as you say.
> 
> diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
> index 2591cacecb7b..afd73a8c6012 100644
> --- a/rust/kernel/devres.rs
> +++ b/rust/kernel/devres.rs
> @@ -14,7 +14,7 @@
>      prelude::*,
>      revocable::{Revocable, RevocableGuard},
>      sync::{rcu, Completion},
> -    types::{ARef, ForeignOwnable, Opaque},
> +    types::{ARef, ForeignOwnable, ScopeGuard, Opaque},
>  };
>  use core::ops::Deref;
> 
> @@ -177,15 +177,15 @@ fn data(&self) -> &Revocable<T> {
>          // hence `ptr` must be a valid pointer to `Inner`.
>          let inner = unsafe { &*ptr.cast::<Inner<T>>() };
> 
> +        // Ensure that `inner` can't be used anymore after we signal completion of this callback.
> +        let inner = ScopeGuard::new_with_data(inner, |inner| inner.devm.complete_all());
> +
>          if !inner.data.revoke() {
>              // If `revoke()` returns false, it means that `Devres::drop` already started revoking
>              // `data` for us. Hence we have to wait until `Devres::drop` signals that it
>              // completed revoking `data`.
>              inner.revoke.wait_for_completion();
>          }
> -
> -        // Signal that we're done using `inner`.
> -        inner.devm.complete_all();
>      }
> 
>      fn remove_action(&self) -> bool {
> 
> Is this what you thought of?

Yep, looks good to me. Thanks!

Regards,
Boqun