[PATCH v4 05/15] rust: types: add `Opaque::raw_get`

[y86-dev@protonmail.com]

From: Benno Lossin <y86-dev@protonmail.com>

This function mirrors `UnsafeCell::raw_get`. It avoids creating a
reference and allows solely using raw pointers.
The `pin-init` API will be using this, since uninitialized memory
requires raw pointers.

Signed-off-by: Benno Lossin <y86-dev@protonmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/types.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 9d0fdbc55843..ff2b2fac951d 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -238,6 +238,14 @@ impl<T> Opaque<T> {
     pub fn get(&self) -> *mut T {
         UnsafeCell::raw_get(self.0.as_ptr())
     }
+
+    /// Gets the value behind `this`.
+    ///
+    /// This function is useful to get access to the value without creating intermediate
+    /// references.
+    pub const fn raw_get(this: *const Self) -> *mut T {
+        UnsafeCell::raw_get(this.cast::<UnsafeCell<T>>())
+    }
 }

 /// A sum type that always holds either a value of type `L` or `R`.
--
2.39.2