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

Danilo Krummrich
2025-06-24T16:20:47Z

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?