linux-kernel - [PATCH v2 03/11] rust: xarray: add `contains

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Message-Id: <20260206-xarray-entry-send-v2-3-91c41673fd30@kernel.org>
Date: Fri, 06 Feb 2026 22:10:49 +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>, 
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
 Vlastimil Babka <vbabka@...e.cz>, Andrew Morton <akpm@...ux-foundation.org>, 
 Christoph Lameter <cl@...two.org>, David Rientjes <rientjes@...gle.com>, 
 Roman Gushchin <roman.gushchin@...ux.dev>, Harry Yoo <harry.yoo@...cle.com>
Cc: Daniel Gomez <da.gomez@...nel.org>, rust-for-linux@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
 Andreas Hindborg <a.hindborg@...nel.org>
Subject: [PATCH v2 03/11] rust: xarray: add `contains_index` method

Add a convenience method `contains_index` to check whether an element
exists at a given index in the XArray. This method provides a more
ergonomic API compared to calling `get` and checking for `Some`.

Signed-off-by: Andreas Hindborg <a.hindborg@...nel.org>
---
 rust/kernel/xarray.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/rust/kernel/xarray.rs b/rust/kernel/xarray.rs
index d9762c6bef19c..ede48b5e1dba3 100644
--- a/rust/kernel/xarray.rs
+++ b/rust/kernel/xarray.rs
@@ -218,6 +218,27 @@ fn load<F, U>(&self, index: usize, f: F) -> Option<U>
         Some(f(ptr))
     }

+    /// Checks if the XArray contains an element at the specified index.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use kernel::{alloc::{flags::GFP_KERNEL, kbox::KBox}, xarray::{AllocKind, XArray}};
+    /// let xa = KBox::pin_init(XArray::new(AllocKind::Alloc), GFP_KERNEL)?;
+    ///
+    /// let mut guard = xa.lock();
+    /// assert_eq!(guard.contains_index(42), false);
+    ///
+    /// guard.store(42, KBox::new(0u32, GFP_KERNEL)?, GFP_KERNEL)?;
+    ///
+    /// assert_eq!(guard.contains_index(42), true);
+    ///
+    /// # Ok::<(), kernel::error::Error>(())
+    /// ```
+    pub fn contains_index(&self, index: usize) -> bool {
+        self.get(index).is_some()
+    }
+
     /// Provides a reference to the element at the given index.
     pub fn get(&self, index: usize) -> Option<T::Borrowed<'_>> {
         self.load(index, |ptr| {

-- 
2.51.2