rust: kernel: require Send for Module implementations

The thread that calls the module initialisation code when a module is
loaded is not guaranteed [in fact, it is unlikely] to be the same one
that calls the module cleanup code on module unload, therefore, `Module`
implementations must be `Send` to account for them moving from one
thread to another implicitly.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Cc: stable@vger.kernel.org # 6.8.x: df70d04d56: rust: phy: implement `Send` for `Registration`
Cc: stable@vger.kernel.org
Fixes: 247b365dc8 ("rust: add `kernel` crate")
Link: https://lore.kernel.org/r/20240328195457.225001-3-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/kernel/lib.rs

@@ -65,7 +65,7 @@ const __LOG_PREFIX: &[u8] = b"rust_kernel\0";
 /// The top level entrypoint to implementing a kernel module.
 ///
 /// For any teardown or cleanup operations, your type may implement [`Drop`].
-pub trait Module: Sized + Sync {
+pub trait Module: Sized + Sync + Send {
     /// Called at module initialization time.
     ///
     /// Use this method to perform whatever setup or registration your module