linux-kernel - [PATCH v2 1/3] rust: xarray: use the prelude

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Message-Id: <20250713-xarray-insert-reserve-v2-1-b939645808a2@gmail.com>
Date: Sun, 13 Jul 2025 08:05:47 -0400
From: Tamir Duberstein <tamird@...il.com>
To: Andreas Hindborg <a.hindborg@...nel.org>, 
 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>, 
 Matthew Wilcox <willy@...radead.org>, 
 Andrew Morton <akpm@...ux-foundation.org>
Cc: rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, 
 Daniel Almeida <daniel.almeida@...labora.com>, 
 Tamir Duberstein <tamird@...il.com>, Janne Grunau <j@...nau.net>
Subject: [PATCH v2 1/3] rust: xarray: use the prelude

Using the prelude is customary in the kernel crate.

This required disambiguating a call to `Iterator::chain` due to the
presence of `pin_init::Init` which also has a `chain` method.

Tested-by: Janne Grunau <j@...nau.net>
Reviewed-by: Janne Grunau <j@...nau.net>
Signed-off-by: Tamir Duberstein <tamird@...il.com>
---
 rust/kernel/xarray.rs | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/rust/kernel/xarray.rs b/rust/kernel/xarray.rs
index 75719e7bb491..b9f4f2cd8d6a 100644
--- a/rust/kernel/xarray.rs
+++ b/rust/kernel/xarray.rs
@@ -5,16 +5,15 @@
 //! C header: [`include/linux/xarray.h`](srctree/include/linux/xarray.h)
 
 use crate::{
-    alloc, bindings, build_assert,
-    error::{Error, Result},
+    alloc,
+    prelude::*,
     types::{ForeignOwnable, NotThreadSafe, Opaque},
 };
-use core::{iter, marker::PhantomData, mem, pin::Pin, ptr::NonNull};
-use pin_init::{pin_data, pin_init, pinned_drop, PinInit};
+use core::{iter, marker::PhantomData, mem, ptr::NonNull};
 
 /// An array which efficiently maps sparse integer indices to owned objects.
 ///
-/// This is similar to a [`crate::alloc::kvec::Vec<Option<T>>`], but more efficient when there are
+/// This is similar to a [`Vec<Option<T>>`], but more efficient when there are
 /// holes in the index space, and can be efficiently grown.
 ///
 /// # Invariants
@@ -105,15 +104,22 @@ fn iter(&self) -> impl Iterator<Item = NonNull<T::PointedTo>> + '_ {
         let mut index = 0;
 
         // SAFETY: `self.xa` is always valid by the type invariant.
-        iter::once(unsafe {
-            bindings::xa_find(self.xa.get(), &mut index, usize::MAX, bindings::XA_PRESENT)
-        })
-        .chain(iter::from_fn(move || {
-            // SAFETY: `self.xa` is always valid by the type invariant.
-            Some(unsafe {
-                bindings::xa_find_after(self.xa.get(), &mut index, usize::MAX, bindings::XA_PRESENT)
-            })
-        }))
+        iter::Iterator::chain(
+            iter::once(unsafe {
+                bindings::xa_find(self.xa.get(), &mut index, usize::MAX, bindings::XA_PRESENT)
+            }),
+            iter::from_fn(move || {
+                // SAFETY: `self.xa` is always valid by the type invariant.
+                Some(unsafe {
+                    bindings::xa_find_after(
+                        self.xa.get(),
+                        &mut index,
+                        usize::MAX,
+                        bindings::XA_PRESENT,
+                    )
+                })
+            }),
+        )
         .map_while(|ptr| NonNull::new(ptr.cast()))
     }
 

-- 
2.50.1