From mboxrd@z Thu Jan  1 00:00:00 1970
From: Claude Code Review Bot <claude-review@example.com>
To: dri-devel-reviews@example.com
Subject: Claude review: rust: devres: add DevresLt for ForLt-aware device resource access
Date: Thu, 04 Jun 2026 12:08:40 +1000
Message-ID: <review-patch5-20260603011020.2073650-6-dakr@kernel.org>
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Patch Review

This is the core new abstraction. The `DevresLt` design is clean:

```rust
pub struct DevresLt<F: ForLt>(Devres<F::Of<'static>>)
where
    F::Of<'static>: Send;
```

The `new()` method's use of `pin_init_from_closure` to cast the slot pointe=
r is sound =E2=80=94 lifetimes don't affect layout:

```rust
let data =3D unsafe {
    pin_init::pin_init_from_closure::<F::Of<'static>, E>(move |slot| {
        data.__pinned_init(slot.cast())
    })
};
```

The `DevresGuard` type cleanly wraps `RevocableGuard` with lifetime shorten=
ing:

```rust
impl<'a, F: CovariantForLt> core::ops::Deref for DevresGuard<'a, F> {
    type Target =3D F::Of<'a>;
    fn deref(&self) -> &Self::Target {
        F::cast_ref(&*self.0)
    }
}
```

**Design question:** `access_with` and `try_access_with` provide `&'a F::Of=
<'a>` (non-pinned), while the auxiliary `registration_data_with` provides `=
Pin<&'a F::Of<'a>>`. This is consistent with the existing `Devres::access` =
API (which returns `&T`, not `Pin<&T>`), but it does mean types that requir=
e `Pin` for access (e.g., types with pinned `Mutex` fields whose methods re=
quire `Pin<&Self>`) can't use `DevresLt`'s closure accessors directly. If t=
his becomes needed, a pinned variant could be added later. Not a blocker fo=
r this series since the current consumers (`Bar`, `IoMem`) don't need pinni=
ng.

**Minor note:** `try_access_with` accesses `self.0.data()` which calls the =
private `Devres::data()` method. This works because `DevresLt` is in the sa=
me module (`devres.rs`).

---
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