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From: Wedson Almeida Filho <wedsonaf@gmail.com>
To: rust-for-linux@vger.kernel.org
Cc: "Miguel Ojeda" <ojeda@kernel.org>,
	"Alex Gaynor" <alex.gaynor@gmail.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Benno Lossin" <benno.lossin@proton.me>,
	"Andreas Hindborg" <a.hindborg@samsung.com>,
	"Alice Ryhl" <aliceryhl@google.com>,
	linux-kernel@vger.kernel.org,
	"Wedson Almeida Filho" <walmeida@microsoft.com>
Subject: [PATCH v2 02/10] rust: alloc: introduce the `VecExt` trait
Date: Tue, 26 Mar 2024 23:35:23 -0300	[thread overview]
Message-ID: <20240327023531.187880-3-wedsonaf@gmail.com> (raw)
In-Reply-To: <20240327023531.187880-1-wedsonaf@gmail.com>

From: Wedson Almeida Filho <walmeida@microsoft.com>

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.

Suggested-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 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 9aa5077d4a4c..2c99635f9fd3 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 000000000000..311e62cc5784
--- /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 51f30e55bd00..7f2841a18d05 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -19,6 +19,7 @@
 #![feature(offset_of)]
 #![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 ae21600970b3..c85b5972c0d3 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};
 
-- 
2.34.1


  parent reply	other threads:[~2024-03-27  2:36 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-27  2:35 [PATCH v2 00/10] Allocation APIs Wedson Almeida Filho
2024-03-27  2:35 ` [PATCH v2 01/10] rust: kernel: move `allocator` module under `alloc` Wedson Almeida Filho
2024-03-27  2:35 ` Wedson Almeida Filho [this message]
2024-03-27 16:45   ` [PATCH v2 02/10] rust: alloc: introduce the `VecExt` trait Benno Lossin
2024-03-27  2:35 ` [PATCH v2 03/10] kbuild: use the upstream `alloc` crate Wedson Almeida Filho
2024-03-27  2:35 ` [PATCH v2 04/10] rust: alloc: remove our fork of the " Wedson Almeida Filho
2024-03-27  2:35 ` [PATCH v2 05/10] rust: alloc: introduce allocation flags Wedson Almeida Filho
2024-03-27  2:35 ` [PATCH v2 06/10] rust: alloc: introduce the `BoxExt` trait Wedson Almeida Filho
2024-03-27 17:09   ` Benno Lossin
2024-03-27 18:43     ` Wedson Almeida Filho
2024-03-27  2:35 ` [PATCH v2 07/10] rust: alloc: update `VecExt` to take allocation flags Wedson Almeida Filho
2024-03-27  3:48   ` Boqun Feng
2024-03-27 10:49     ` Miguel Ojeda
2024-03-27 18:19     ` Wedson Almeida Filho
2024-03-27  2:35 ` [PATCH v2 08/10] rust: sync: update `Arc` and `UniqueArc` " Wedson Almeida Filho
2024-03-27  2:35 ` [PATCH v2 09/10] rust: init: update `init` module " Wedson Almeida Filho
2024-03-27  2:35 ` [PATCH v2 10/10] rust: kernel: remove usage of `allocator_api` unstable feature Wedson Almeida Filho
2024-03-27 17:19   ` Benno Lossin

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