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: return reference in `devres::register`
Date: Thu, 04 Jun 2026 15:57:27 +1000
Message-ID: <review-patch1-20260530-rust_serdev-v8-1-2a95f1da22a7@posteo.de>
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Patch Review

This changes `devres::register` from returning `Result` (unit) to `Result<&=
'a T>`, allowing callers to obtain a reference to the devres-managed data. =
The lifetime `'a` is tied to the `&'a Device<Bound>` borrow, which ensures =
the reference can't outlive the bound state (during which devres won't fire=
).

The safety argument is sound: `data_ptr` is obtained from the `Pin<KBox<T>>=
` heap allocation before the `KBox` is moved into `register_foreign`. The m=
ove only transfers ownership of the heap pointer =E2=80=94 the allocation i=
tself doesn't move, so `data_ptr` remains valid. After registration, devres=
 owns the allocation and keeps it alive until unbind.

```rust
+    let data_ptr =3D &raw const *data;
+
     register_foreign(dev, data)
+        // SAFETY: `dev` is valid for the lifetime of 'a. As long as there=
 is a reference to
+        // `Device<Bound>`, it is guaranteed that the device is not unboun=
d and data has not been
+        // dropped. Thus `data_ptr` is also valid for the lifetime of 'a.
+        .map(|()| unsafe { &*data_ptr })
```

The existing callers (`cpufreq.rs`, `drm/driver.rs`) are updated to discard=
 the new return value with `?; Ok(())`, preserving their existing behavior.=
 Clean mechanical adaptation.

Reviewed-by quality: **Good.** Already has Viresh Kumar's Ack.

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