From 03989773a94490383b062912feb0c4d175f20845 Mon Sep 17 00:00:00 2001
From: Wedson Almeida Filho <walmeida@microsoft.com>
Date: Wed, 27 Mar 2024 22:35:55 -0300
Subject: [PATCH] rust: alloc: introduce the `VecExt` trait
Make `try_with_capacity`, `try_push`, and `try_extend_from_slice`
methods available in `Vec` even though it doesn't implement them. It is
implemented with `try_reserve` and `push_within_capacity`.
This is in preparation for switching to the upstream `alloc` crate.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Suggested-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20240328013603.206764-3-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
rust/kernel/alloc.rs | 1 +
rust/kernel/alloc/vec_ext.rs | 48 ++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
rust/kernel/prelude.rs | 2 ++
4 files changed, 52 insertions(+)
create mode 100644 rust/kernel/alloc/vec_ext.rs
diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index 9aa5077d4a4c8..2c99635f9fd35 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -5,3 +5,4 @@
#[cfg(not(test))]
#[cfg(not(testlib))]
mod allocator;
+pub mod vec_ext;
diff --git a/rust/kernel/alloc/vec_ext.rs b/rust/kernel/alloc/vec_ext.rs
new file mode 100644
index 0000000000000..311e62cc57845
--- /dev/null
+++ b/rust/kernel/alloc/vec_ext.rs
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Extensions to [`Vec`] for fallible allocations.
+
+use alloc::{collections::TryReserveError, vec::Vec};
+use core::result::Result;
+
+/// Extensions to [`Vec`].
+pub trait VecExt<T>: Sized {
+ /// Creates a new [`Vec`] instance with at least the given capacity.
+ fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError>;
+
+ /// Appends an element to the back of the [`Vec`] instance.
+ fn try_push(&mut self, v: T) -> Result<(), TryReserveError>;
+
+ /// Pushes clones of the elements of slice into the [`Vec`] instance.
+ fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
+ where
+ T: Clone;
+}
+
+impl<T> VecExt<T> for Vec<T> {
+ fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
+ let mut v = Vec::new();
+ v.try_reserve(capacity)?;
+ Ok(v)
+ }
+
+ fn try_push(&mut self, v: T) -> Result<(), TryReserveError> {
+ if let Err(retry) = self.push_within_capacity(v) {
+ self.try_reserve(1)?;
+ let _ = self.push_within_capacity(retry);
+ }
+ Ok(())
+ }
+
+ fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
+ where
+ T: Clone,
+ {
+ self.try_reserve(other.len())?;
+ for item in other {
+ self.try_push(item.clone())?;
+ }
+
+ Ok(())
+ }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 1e910fe7c2c77..d3d345aed218a 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -18,6 +18,7 @@
#![feature(new_uninit)]
#![feature(receiver_trait)]
#![feature(unsize)]
+#![feature(vec_push_within_capacity)]
// Ensure conditional compilation based on the kernel configuration works;
// otherwise we may silently break things like initcall handling.
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index ae21600970b39..c85b5972c0d37 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -14,6 +14,8 @@
#[doc(no_inline)]
pub use core::pin::Pin;
+pub use crate::alloc::vec_ext::VecExt;
+
#[doc(no_inline)]
pub use alloc::{boxed::Box, vec::Vec};
--
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