[PATCH] rust: debugfs: Implement Reader for Mutex<T> only when T is Unpin

[Boqun Feng]

Since we are going to make `Mutex<T>` structurally pin the data (i.e.
`T`), therefore `.lock()` function only returns a `Guard` that can
dereference a mutable reference to `T` if only `T` is `Unpin`, therefore
restrict the impl `Reader` block of `Mutex<T>` to that.

Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
---
 rust/kernel/debugfs/traits.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/debugfs/traits.rs b/rust/kernel/debugfs/traits.rs
index ab009eb254b3..ba7ec5a900b8 100644
--- a/rust/kernel/debugfs/traits.rs
+++ b/rust/kernel/debugfs/traits.rs
@@ -50,7 +50,7 @@ pub trait Reader {
     fn read_from_slice(&self, reader: &mut UserSliceReader) -> Result;
 }
 
-impl<T: FromStr> Reader for Mutex<T> {
+impl<T: FromStr + Unpin> Reader for Mutex<T> {
     fn read_from_slice(&self, reader: &mut UserSliceReader) -> Result {
         let mut buf = [0u8; 128];
         if reader.len() > buf.len() {
-- 
2.51.0