From: Boqun Feng <boqun.feng@gmail.com>
Date: Wed, 22 Oct 2025 03:42:37 +0000 (-0400)
Subject: rust: debugfs: Implement Reader for Mutex<T> only when T is Unpin
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=37d0472c8ac441af8bc10fc4959ad9d62dd5fa4c;p=thirdparty%2Flinux.git

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

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@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/20251022034237.70431-1-boqun.feng@gmail.com
---

diff --git a/rust/kernel/debugfs/traits.rs b/rust/kernel/debugfs/traits.rs
index ab009eb254b32..ba7ec5a900b8f 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() {