[PATCH] rust: sync: create the `get_mut()` function

[Guilherme Giacomo Simoes <trintaeoitogc@gmail.com>]

Create a `get_mut()` function that receive a mutable instance of Lock,
and return a mutable reference to data because if the instance is
mutable, the rust compiler guarantee the access control.

Suggested-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Signed-off-by: Guilherme Giacomo Simoes <trintaeoitogc@gmail.com>
---
 rust/kernel/sync/lock.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index eb80048e0110..3f9d78bcb37c 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -140,6 +140,12 @@ pub fn new(t: T, name: &'static CStr, key: &'static LockClassKey) -> impl PinIni
             }),
         })
     }
+
+    /// Get a mutable reference to data
+    pub fn get_mut(&mut self) -> &mut T {
+        // SAFETY: the caller must guarantee that the instance is only used in one place
+        unsafe { &mut *self.data.get() }
+    }
 }
 
 impl<B: Backend> Lock<(), B> {
-- 
2.34.1