[PATCH 6.6 021/269] rust: types: Make Opaque::get const

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Boqun Feng <boqun.feng@xxxxxxxxx>

commit be2ca1e03965ffb214b6cbda0ffd84daeeb5f214 upstream.

To support a potential usage:

    static foo: Opaque<Foo> = ..; // Or defined in an extern block.

    ...

    fn bar() {
        let ptr = foo.get();
    }

`Opaque::get` need to be `const`, otherwise compiler will complain
because calls on statics are limited to const functions.

Also `Opaque::get` should be naturally `const` since it's a composition
of two `const` functions: `UnsafeCell::get` and `ptr::cast`.

Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Reviewed-by: Wedson Almeida Filho <walmeida@xxxxxxxxxxxxx>
Reviewed-by: Benno Lossin <benno.lossin@xxxxxxxxx>
Link: https://lore.kernel.org/r/20240401214543.1242286-1-boqun.feng@xxxxxxxxx
Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 rust/kernel/types.rs |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -248,7 +248,7 @@ impl<T> Opaque<T> {
     }
 
     /// Returns a raw pointer to the opaque data.
-    pub fn get(&self) -> *mut T {
+    pub const fn get(&self) -> *mut T {
         UnsafeCell::get(&self.value).cast::<T>()
     }