Commit da123f0e authored Sep 19, 2025 by Daniel Almeida Committed by Peter Zijlstra Oct 21, 2025

rust: lock: guard: Add T: Unpin bound to DerefMut



A core property of pinned types is not handing a mutable reference to
the inner data in safe code, as this trivially allows that data to be
moved.

Enforce this condition by adding a bound on lock::Guard's DerefMut
implementation, so that it's only implemented for pinning-agnostic
types.

Suggested-by: Benno Lossin <lossin@kernel.org>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://github.com/Rust-for-Linux/linux/issues/1181

parent c14ecb55

rust/kernel/sync/lock.rs

+4 −1

Original line number	Diff line number	Diff line
		@@ -251,7 +251,10 @@ fn deref(&self) -> &Self::Target {
		}
		}

		impl<T: ?Sized, B: Backend> core::ops::DerefMut for Guard<'_, T, B> {
		impl<T: ?Sized, B: Backend> core::ops::DerefMut for Guard<'_, T, B>
		where
		T: Unpin,
		{
		fn deref_mut(&mut self) -> &mut Self::Target {
		// SAFETY: The caller owns the lock, so it is safe to deref the protected data.
		unsafe { &mut *self.lock.data.get() }

rust/kernel/sync/lock/global.rs

+4 −1

Original line number	Diff line number	Diff line
		@@ -106,7 +106,10 @@ fn deref(&self) -> &Self::Target {
		}
		}

		impl<B: GlobalLockBackend> core::ops::DerefMut for GlobalGuard<B> {
		impl<B: GlobalLockBackend> core::ops::DerefMut for GlobalGuard<B>
		where
		B::Item: Unpin,
		{
		fn deref_mut(&mut self) -> &mut Self::Target {
		&mut self.inner
		}