[PATCH] rust: configfs: require Send data for Subsystem

[Yilin Chen <1479826151@qq.com>]

Subsystem stores its data by value, but its blanket Send implementation
did not require the data to be Send. This allowed a configfs subsystem
containing a non-Send value to be transferred across threads.

Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Should.20add.20Data.3A.20Send.2FSync.20bounds.20in.20configfs.3A.3ASubsystem.3F/with/623719979

Fixes: 446cafc295bf ("rust: configfs: introduce rust support for configfs")

Assisted-by: Gpt-5.6 Sol

Signed-off-by: Yilin Chen <1479826151@qq.com>
---
 rust/kernel/configfs.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/configfs.rs b/rust/kernel/configfs.rs
index cd082b83e9e7..f8ca5fc03bf1 100644
--- a/rust/kernel/configfs.rs
+++ b/rust/kernel/configfs.rs
@@ -135,8 +135,9 @@ pub struct Subsystem<Data> {
 // SAFETY: We do not provide any operations on `Subsystem`.
 unsafe impl<Data> Sync for Subsystem<Data> {}
 
-// SAFETY: Ownership of `Subsystem` can safely be transferred to other threads.
-unsafe impl<Data> Send for Subsystem<Data> {}
+// SAFETY: Ownership of `Subsystem` can safely be transferred to other threads
+// if its data can be transferred as well.
+unsafe impl<Data: Send> Send for Subsystem<Data> {}
 
 impl<Data> Subsystem<Data> {
     /// Create an initializer for a [`Subsystem`].

base-commit: 08df884136f1c1197bab2a27814404fd329d9aac