rust: device: narrow the generic of drvdata_obtain()

Let T be the actual private driver data type without the surrounding
box, as it leaves less room for potential bugs.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

rust/kernel/auxiliary.rs

@@ -85,7 +85,7 @@ impl<T: Driver + 'static> Adapter<T> {
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T>>`.
-        drop(unsafe { adev.as_ref().drvdata_obtain::<Pin<KBox<T>>>() });
+        drop(unsafe { adev.as_ref().drvdata_obtain::<T>() });
     }
 }
 

rust/kernel/device.rs

@@ -215,7 +215,7 @@ impl Device<CoreInternal> {
     /// - Must only be called once after a preceding call to [`Device::set_drvdata`].
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
-    pub unsafe fn drvdata_obtain<T: ForeignOwnable>(&self) -> T {
+    pub unsafe fn drvdata_obtain<T: 'static>(&self) -> Pin<KBox<T>> {
         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
         let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) };
 
@@ -224,7 +224,7 @@ impl Device<CoreInternal> {
         //   `into_foreign()`.
         // - `dev_get_drvdata()` guarantees to return the same pointer given to `dev_set_drvdata()`
         //   in `into_foreign()`.
-        unsafe { T::from_foreign(ptr.cast()) }
+        unsafe { Pin::<KBox<T>>::from_foreign(ptr.cast()) }
     }
 
     /// Borrow the driver's private data bound to this [`Device`].

rust/kernel/pci.rs

@@ -94,7 +94,7 @@ impl<T: Driver + 'static> Adapter<T> {
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { pdev.as_ref().drvdata_obtain::<Pin<KBox<T>>>() };
+        let data = unsafe { pdev.as_ref().drvdata_obtain::<T>() };
 
         T::unbind(pdev, data.as_ref());
     }

rust/kernel/platform.rs

@@ -91,7 +91,7 @@ impl<T: Driver + 'static> Adapter<T> {
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { pdev.as_ref().drvdata_obtain::<Pin<KBox<T>>>() };
+        let data = unsafe { pdev.as_ref().drvdata_obtain::<T>() };
 
         T::unbind(pdev, data.as_ref());
     }

rust/kernel/usb.rs

@@ -87,9 +87,9 @@ impl<T: Driver + 'static> Adapter<T> {
         // SAFETY: `disconnect_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { dev.drvdata_obtain::<Pin<KBox<T>>>() };
+        let data = unsafe { dev.drvdata_obtain::<T>() };
 
-        T::disconnect(intf, data.as_ref());
+        T::disconnect(intf, data.data());
     }
 }