rust: revocable: implement Revocable::access()

Implement an unsafe direct accessor for the data stored within the
Revocable.

This is useful for cases where we can prove that the data stored within
the Revocable is not and cannot be revoked for the duration of the
lifetime of the returned reference.

Reviewed-by: Christian Schrefl <chrisi.schrefl@gmail.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Link: https://lore.kernel.org/r/20250428140137.468709-2-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

diff --git a/rust/kernel/revocable.rs b/rust/kernel/revocable.rs
index 971d0dc38d83dbb971dbf498ddbce38c51c24f2f..db4aa46bb1216d18868dcbdcb0b7033a757306b1 100644 (file)
--- a/rust/kernel/revocable.rs
+++ b/rust/kernel/revocable.rs
@@ -139,6 +139,18 @@ impl<T> Revocable<T> {
         self.try_access().map(|t| f(&*t))
     }
 
+    /// Directly access the revocable wrapped object.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure this [`Revocable`] instance hasn't been revoked and won't be revoked
+    /// as long as the returned `&T` lives.
+    pub unsafe fn access(&self) -> &T {
+        // SAFETY: By the safety requirement of this function it is guaranteed that
+        // `self.data.get()` is a valid pointer to an instance of `T`.
+        unsafe { &*self.data.get() }
+    }
+
     /// # Safety
     ///
     /// Callers must ensure that there are no more concurrent users of the revocable object.