Re: [PATCH v6 3/3] rust: revocable: Document RevocableGuard invariants and refine Deref safety

["Benno Lossin" <lossin@kernel.org>]

On Wed Jul 9, 2025 at 12:24 AM CEST, Marcelo Moreira wrote:
> Em ter., 8 de jul. de 2025 às 12:04, Benno Lossin <lossin@kernel.org> escreveu:
>> On Tue Jul 8, 2025 at 2:33 AM CEST, Marcelo Moreira wrote:
>> >  pub struct RevocableGuard<'a, T> {
>> >      // This can't use the `&'a T` type because references that appear in function arguments must
>> >      // not become dangling during the execution of the function, which can happen if the
>> > @@ -258,8 +259,8 @@ impl<T> Deref for RevocableGuard<'_, T> {
>> >      type Target = T;
>> >
>> >      fn deref(&self) -> &Self::Target {
>> > -        // SAFETY: By the type invariants, we hold the rcu read-side lock, so the object is
>> > -        // guaranteed to remain valid.
>> > +        // SAFETY: `self.data_ref` is valid for writes because of `Self`'s type invariants,
>> > +        // and `_rcu_guard` ensures the data's accessibility for the lifetime of this guard.
>>
>> This also needs to be adjusted.
>
> oh, of course, &T is an immutable reference, mb.
>
> What about:
> // SAFETY: `self.data_ref` is valid because of `Self`'s type invariants
> // and the active RCU read-side lock held via `_rcu_guard`, ensuring
> the data's accessibility.

Sounds good.

---
Cheers,
Benno