linux-kernel - [PATCH 05/10] rust: xarray: use `xas_load` instead of `xa

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Message-Id: <20251203-xarray-entry-send-v1-5-9e5ffd5e3cf0@kernel.org>
Date: Wed, 03 Dec 2025 23:26:35 +0100
From: Andreas Hindborg <a.hindborg@...nel.org>
To: Tamir Duberstein <tamird@...il.com>, Miguel Ojeda <ojeda@...nel.org>, 
 Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>, 
 Gary Guo <gary@...yguo.net>, 
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
 Benno Lossin <lossin@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, 
 Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>
Cc: Daniel Gomez <da.gomez@...nel.org>, rust-for-linux@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Andreas Hindborg <a.hindborg@...nel.org>
Subject: [PATCH 05/10] rust: xarray: use `xas_load` instead of `xa_load` in
 `Guard::load`

Replace the call to `xa_load` with `xas_load` in `Guard::load`. The
`xa_load` function takes the XArray lock internally, which would cause
a double lock since the `Guard` already holds the lock. The `xas_load`
function operates on XArray state and assumes the lock is already held,
which is the correct API to use when holding a `Guard`.

This change also removes the `#[expect(dead_code)]` annotation from
`XArrayState` and its constructor, as they are now in use.

Signed-off-by: Andreas Hindborg <a.hindborg@...nel.org>
---
 rust/kernel/xarray.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/rust/kernel/xarray.rs b/rust/kernel/xarray.rs
index f6e610b059625..0f69a523b72bf 100644
--- a/rust/kernel/xarray.rs
+++ b/rust/kernel/xarray.rs
@@ -215,8 +215,10 @@ fn load<F, U>(&self, index: usize, f: F) -> Option<U>
     where
         F: FnOnce(NonNull<c_void>) -> U,
     {
-        // SAFETY: `self.xa.xa` is always valid by the type invariant.
-        let ptr = unsafe { bindings::xa_load(self.xa.xa.get(), index) };
+        let mut state = XArrayState::new(self, index);
+        // SAFETY: `state.state` is always valid by the type invariant of
+        // `XArrayState`.
+        let ptr = unsafe { bindings::xas_load(&raw mut state.state) };
         let ptr = NonNull::new(ptr.cast())?;
         Some(f(ptr))
     }
@@ -327,7 +329,6 @@ pub fn store(
 /// # Invariants
 ///
 /// - `state` is always a valid `bindings::xa_state`.
-#[expect(dead_code)]
 pub(crate) struct XArrayState<'a, 'b, T: ForeignOwnable> {
     /// Holds a reference to the lock guard to ensure the lock is not dropped
     /// while `Self` is live.
@@ -336,7 +337,6 @@ pub(crate) struct XArrayState<'a, 'b, T: ForeignOwnable> {
 }
 
 impl<'a, 'b, T: ForeignOwnable> XArrayState<'a, 'b, T> {
-    #[expect(dead_code)]
     fn new(access: &'b Guard<'a, T>, index: usize) -> Self {
         let ptr = access.xa.xa.get();
         // INVARIANT: We initialize `self.state` to a valid value below.

-- 
2.51.2