[PATCH v5 10/24] rust: device: implement Sync for Device<Bound>

[Danilo Krummrich]

Implement Sync for Device<Bound> in addition to Device<Normal>.

Device<Bound> uses the same underlying struct device as Device<Normal>;
Bound is a zero-sized type-state marker that does not affect thread
safety.

This is needed for types that hold &'bound Device<Bound>, such as
io::mem::IoMem, to be Send.

Reviewed-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
 rust/kernel/device.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index 5df8fa108a52..c4486f4b8c40 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -467,6 +467,10 @@ unsafe impl Send for Device {}
 // synchronization in `struct device`.
 unsafe impl Sync for Device {}
 
+// SAFETY: Same as `Device<Normal>` -- the underlying `struct device` is the same; `Bound` is a
+// zero-sized type-state marker that does not affect thread safety.
+unsafe impl Sync for Device<Bound> {}
+
 /// Marker trait for the context or scope of a bus specific device.
 ///
 /// [`DeviceContext`] is a marker trait for types representing the context of a bus specific
-- 
2.54.0