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Message-ID: <20250816211900.2731720-1-ojeda@kernel.org>
Date: Sat, 16 Aug 2025 23:19:00 +0200
From: Miguel Ojeda <ojeda@...nel.org>
To: Danilo Krummrich <dakr@...nel.org>,
Miguel Ojeda <ojeda@...nel.org>,
Alex Gaynor <alex.gaynor@...il.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>,
"Liam R . Howlett" <Liam.Howlett@...cle.com>,
Uladzislau Rezki <urezki@...il.com>,
rust-for-linux@...r.kernel.org,
Boqun Feng <boqun.feng@...il.com>,
Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <lossin@...nel.org>,
Andreas Hindborg <a.hindborg@...nel.org>,
Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>,
linux-kernel@...r.kernel.org,
patches@...ts.linux.dev
Subject: [PATCH] rust: alloc: remove `allocator_test`
Given we do not have tests that rely on it anymore, remove
`allocator_test`, which simplifies the complexity of the build.
In particular, it avoids potential issues with `rusttest`, such as the
one fixed at [1], where a public function was added to `Kmalloc` and
used elsewhere, but it was not added to `Cmalloc`; or trivial issues
like a missing import [2] due to not many people testing that target.
The only downside is that we cannot use it in the `macros`' crate
examples anymore, but we did not feel a need for that so far, and anyway
we could support that by running those within the kernel too, which we
may do regardless.
Link: https://lore.kernel.org/rust-for-linux/20250816204215.2719559-1-ojeda@kernel.org/ [1]
Link: https://lore.kernel.org/rust-for-linux/20250816210214.2729269-1-ojeda@kernel.org/ [2]
Signed-off-by: Miguel Ojeda <ojeda@...nel.org>
---
This one goes on top of:
https://lore.kernel.org/rust-for-linux/20250726180750.2735836-1-ojeda@kernel.org/
rust/kernel/alloc.rs | 7 --
rust/kernel/alloc/allocator_test.rs | 113 ----------------------------
2 files changed, 120 deletions(-)
delete mode 100644 rust/kernel/alloc/allocator_test.rs
diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index 335ae3271fa8..6a3d45a5eb24 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -2,18 +2,11 @@
//! Implementation of the kernel's memory allocation infrastructure.
-#[cfg(not(testlib))]
pub mod allocator;
pub mod kbox;
pub mod kvec;
pub mod layout;
-#[cfg(testlib)]
-pub mod allocator_test;
-
-#[cfg(testlib)]
-pub use self::allocator_test as allocator;
-
pub use self::kbox::Box;
pub use self::kbox::KBox;
pub use self::kbox::KVBox;
diff --git a/rust/kernel/alloc/allocator_test.rs b/rust/kernel/alloc/allocator_test.rs
deleted file mode 100644
index a3074480bd8d..000000000000
--- a/rust/kernel/alloc/allocator_test.rs
+++ /dev/null
@@ -1,113 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-//! So far the kernel's `Box` and `Vec` types can't be used by userspace test cases, since all users
-//! of those types (e.g. `CString`) use kernel allocators for instantiation.
-//!
-//! In order to allow userspace test cases to make use of such types as well, implement the
-//! `Cmalloc` allocator within the `allocator_test` module and type alias all kernel allocators to
-//! `Cmalloc`. The `Cmalloc` allocator uses libc's `realloc()` function as allocator backend.
-
-#![allow(missing_docs)]
-
-use super::{flags::*, AllocError, Allocator, Flags};
-use core::alloc::Layout;
-use core::cmp;
-use core::ptr;
-use core::ptr::NonNull;
-
-/// The userspace allocator based on libc.
-pub struct Cmalloc;
-
-pub type Kmalloc = Cmalloc;
-pub type Vmalloc = Kmalloc;
-pub type KVmalloc = Kmalloc;
-
-extern "C" {
- #[link_name = "aligned_alloc"]
- fn libc_aligned_alloc(align: usize, size: usize) -> *mut crate::ffi::c_void;
-
- #[link_name = "free"]
- fn libc_free(ptr: *mut crate::ffi::c_void);
-}
-
-// SAFETY:
-// - memory remains valid until it is explicitly freed,
-// - passing a pointer to a valid memory allocation created by this `Allocator` is always OK,
-// - `realloc` provides the guarantees as provided in the `# Guarantees` section.
-unsafe impl Allocator for Cmalloc {
- unsafe fn realloc(
- ptr: Option<NonNull<u8>>,
- layout: Layout,
- old_layout: Layout,
- flags: Flags,
- ) -> Result<NonNull<[u8]>, AllocError> {
- let src = match ptr {
- Some(src) => {
- if old_layout.size() == 0 {
- ptr::null_mut()
- } else {
- src.as_ptr()
- }
- }
- None => ptr::null_mut(),
- };
-
- if layout.size() == 0 {
- // SAFETY: `src` is either NULL or was previously allocated with this `Allocator`
- unsafe { libc_free(src.cast()) };
-
- return Ok(NonNull::slice_from_raw_parts(
- crate::alloc::dangling_from_layout(layout),
- 0,
- ));
- }
-
- // ISO C (ISO/IEC 9899:2011) defines `aligned_alloc`:
- //
- // > The value of alignment shall be a valid alignment supported by the implementation
- // [...].
- //
- // As an example of the "supported by the implementation" requirement, POSIX.1-2001 (IEEE
- // 1003.1-2001) defines `posix_memalign`:
- //
- // > The value of alignment shall be a power of two multiple of sizeof (void *).
- //
- // and POSIX-based implementations of `aligned_alloc` inherit this requirement. At the time
- // of writing, this is known to be the case on macOS (but not in glibc).
- //
- // Satisfy the stricter requirement to avoid spurious test failures on some platforms.
- let min_align = core::mem::size_of::<*const crate::ffi::c_void>();
- let layout = layout.align_to(min_align).map_err(|_| AllocError)?;
- let layout = layout.pad_to_align();
-
- // SAFETY: Returns either NULL or a pointer to a memory allocation that satisfies or
- // exceeds the given size and alignment requirements.
- let dst = unsafe { libc_aligned_alloc(layout.align(), layout.size()) }.cast::<u8>();
- let dst = NonNull::new(dst).ok_or(AllocError)?;
-
- if flags.contains(__GFP_ZERO) {
- // SAFETY: The preceding calls to `libc_aligned_alloc` and `NonNull::new`
- // guarantee that `dst` points to memory of at least `layout.size()` bytes.
- unsafe { dst.as_ptr().write_bytes(0, layout.size()) };
- }
-
- if !src.is_null() {
- // SAFETY:
- // - `src` has previously been allocated with this `Allocator`; `dst` has just been
- // newly allocated, hence the memory regions do not overlap.
- // - both` src` and `dst` are properly aligned and valid for reads and writes
- unsafe {
- ptr::copy_nonoverlapping(
- src,
- dst.as_ptr(),
- cmp::min(layout.size(), old_layout.size()),
- )
- };
- }
-
- // SAFETY: `src` is either NULL or was previously allocated with this `Allocator`
- unsafe { libc_free(src.cast()) };
-
- Ok(NonNull::slice_from_raw_parts(dst, layout.size()))
- }
-}
--
2.50.1
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