[RFC 4/5] rust: sync: Add MutexGuard type alias

[Boqun Feng]

From: Lyude Paul <lyude@xxxxxxxxxx>

A simple helper alias for code that needs to deal with Guard types returned
from Mutexes.

Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Link: https://lore.kernel.org/r/20241120222742.2490495-2-lyude@xxxxxxxxxx
---
 rust/kernel/sync.rs            | 2 +-
 rust/kernel/sync/lock/mutex.rs | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs
index 1eab7ebf25fd..2721b5c8deda 100644
--- a/rust/kernel/sync.rs
+++ b/rust/kernel/sync.rs
@@ -16,7 +16,7 @@
 pub use arc::{Arc, ArcBorrow, UniqueArc};
 pub use condvar::{new_condvar, CondVar, CondVarTimeoutResult};
 pub use lock::global::{global_lock, GlobalGuard, GlobalLock, GlobalLockBackend, GlobalLockedBy};
-pub use lock::mutex::{new_mutex, Mutex};
+pub use lock::mutex::{new_mutex, Mutex, MutexGuard};
 pub use lock::spinlock::{new_spinlock, SpinLock};
 pub use locked_by::LockedBy;
 
diff --git a/rust/kernel/sync/lock/mutex.rs b/rust/kernel/sync/lock/mutex.rs
index 0e946ebefce1..10a70c07268d 100644
--- a/rust/kernel/sync/lock/mutex.rs
+++ b/rust/kernel/sync/lock/mutex.rs
@@ -86,6 +86,14 @@ macro_rules! new_mutex {
 /// [`struct mutex`]: srctree/include/linux/mutex.h
 pub type Mutex<T> = super::Lock<T, MutexBackend>;
 
+/// A [`Guard`] acquired from locking a [`Mutex`].
+///
+/// This is simply a type alias for a [`Guard`] returned from locking a [`Mutex`]. It will unlock
+/// the [`Mutex`] upon being dropped.
+///
+/// [`Guard`]: super::Guard
+pub type MutexGuard<'a, T> = super::Guard<'a, T, MutexBackend>;
+
 /// A kernel `struct mutex` lock backend.
 pub struct MutexBackend;
 
-- 
2.39.5 (Apple Git-154)