linux-kernel - [PATCH 2/3] rust: alloc: add Vec::resize method

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Message-ID: <20250315024235.5282-3-andrewjballance@gmail.com>
Date: Fri, 14 Mar 2025 21:42:34 -0500
From: Andrew Ballance <andrewjballance@...il.com>
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Subject: [PATCH 2/3] rust: alloc: add Vec::resize method

implemnts the equivalent of the rust std's Vec::resize
on the kernel's Vec type.

Signed-off-by: Andrew Ballance <andrewjballance@...il.com>
---
 rust/kernel/alloc/kvec.rs | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs
index 75e9feebb81f..cbfef2e56f9c 100644
--- a/rust/kernel/alloc/kvec.rs
+++ b/rust/kernel/alloc/kvec.rs
@@ -554,6 +554,31 @@ pub fn from_elem(value: T, n: usize, flags: Flags) -> Result<Self, AllocError> {
 
         Ok(v)
     }
+
+    /// Resizes the [`Vec`] so that `len` is equal to `new_len`.
+    ///
+    /// If `new_len` is smaller than `len`, the `Vec` is [`Vec::truncate`]d.
+    /// If `new_len` is larger, each new slot is filled with clones of `value`.
+    ///
+    /// # Example
+    /// ```
+    /// let mut v = kernel::kvec![1, 2, 3]?;
+    /// v.resize(1, 42, GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1]);
+    ///
+    /// v.resize(3, 42, GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1, 42, 42]);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn resize(&mut self, new_len: usize, value: T, flags: Flags) -> Result<(), AllocError> {
+        if new_len > self.len() {
+            self.extend_with(new_len - self.len(), value, flags)
+        } else {
+            self.truncate(new_len);
+            Ok(())
+        }
+    }
 }
 
 impl<T, A> Drop for Vec<T, A>
-- 
2.48.1