Merge 1ef4cf5f98 ("rust: alloc: update module comment of alloc.rs") into android16-6.12

Steps on the way to 6.12.18

Resolves merge conflicts in:
	rust/kernel/types.rs
	scripts/Makefile.build

Change-Id: I1a0d7a30074e2532f53b9c9d4cf0e8346d57ffef
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
[Re-resolved rust/kernel/types.rs <mmaurer@google.com>]
Signed-off-by: Matthew Maurer <mmaurer@google.com>

.clippy.toml

@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+
+check-private-items = true
+
+disallowed-macros = [
+    # The `clippy::dbg_macro` lint only works with `std::dbg!`, thus we simulate
+    # it here, see: https://github.com/rust-lang/rust-clippy/issues/11303.
+    { path = "kernel::dbg", reason = "the `dbg!` macro is intended as a debugging tool" },
+]

.gitignore

@@ -103,6 +103,7 @@ modules.order
 # We don't want to ignore the following even if they are dot-files
 #
 !.clang-format
+!.clippy.toml
 !.cocciconfig
 !.editorconfig
 !.get_maintainer.ignore

Documentation/rust/coding-guidelines.rst

@@ -227,3 +227,151 @@ The equivalent in Rust may look like (ignoring documentation):
 That is, the equivalent of ``GPIO_LINE_DIRECTION_IN`` would be referred to as
 ``gpio::LineDirection::In``. In particular, it should not be named
 ``gpio::gpio_line_direction::GPIO_LINE_DIRECTION_IN``.
+
+
+Lints
+-----
+
+In Rust, it is possible to ``allow`` particular warnings (diagnostics, lints)
+locally, making the compiler ignore instances of a given warning within a given
+function, module, block, etc.
+
+It is similar to ``#pragma GCC diagnostic push`` + ``ignored`` + ``pop`` in C
+[#]_:
+
+.. code-block:: c
+
+	#pragma GCC diagnostic push
+	#pragma GCC diagnostic ignored "-Wunused-function"
+	static void f(void) {}
+	#pragma GCC diagnostic pop
+
+.. [#] In this particular case, the kernel's ``__{always,maybe}_unused``
+       attributes (C23's ``[[maybe_unused]]``) may be used; however, the example
+       is meant to reflect the equivalent lint in Rust discussed afterwards.
+
+But way less verbose:
+
+.. code-block:: rust
+
+	#[allow(dead_code)]
+	fn f() {}
+
+By that virtue, it makes it possible to comfortably enable more diagnostics by
+default (i.e. outside ``W=`` levels). In particular, those that may have some
+false positives but that are otherwise quite useful to keep enabled to catch
+potential mistakes.
+
+On top of that, Rust provides the ``expect`` attribute which takes this further.
+It makes the compiler warn if the warning was not produced. For instance, the
+following will ensure that, when ``f()`` is called somewhere, we will have to
+remove the attribute:
+
+.. code-block:: rust
+
+	#[expect(dead_code)]
+	fn f() {}
+
+If we do not, we get a warning from the compiler::
+
+	warning: this lint expectation is unfulfilled
+	 --> x.rs:3:10
+	  |
+	3 | #[expect(dead_code)]
+	  |          ^^^^^^^^^
+	  |
+	  = note: `#[warn(unfulfilled_lint_expectations)]` on by default
+
+This means that ``expect``\ s do not get forgotten when they are not needed, which
+may happen in several situations, e.g.:
+
+- Temporary attributes added while developing.
+
+- Improvements in lints in the compiler, Clippy or custom tools which may
+  remove a false positive.
+
+- When the lint is not needed anymore because it was expected that it would be
+  removed at some point, such as the ``dead_code`` example above.
+
+It also increases the visibility of the remaining ``allow``\ s and reduces the
+chance of misapplying one.
+
+Thus prefer ``except`` over ``allow`` unless:
+
+- The lint attribute is intended to be temporary, e.g. while developing.
+
+- Conditional compilation triggers the warning in some cases but not others.
+
+  If there are only a few cases where the warning triggers (or does not
+  trigger) compared to the total number of cases, then one may consider using
+  a conditional ``expect`` (i.e. ``cfg_attr(..., expect(...))``). Otherwise,
+  it is likely simpler to just use ``allow``.
+
+- Inside macros, when the different invocations may create expanded code that
+  triggers the warning in some cases but not in others.
+
+- When code may trigger a warning for some architectures but not others, such
+  as an ``as`` cast to a C FFI type.
+
+As a more developed example, consider for instance this program:
+
+.. code-block:: rust
+
+	fn g() {}
+
+	fn main() {
+	    #[cfg(CONFIG_X)]
+	    g();
+	}
+
+Here, function ``g()`` is dead code if ``CONFIG_X`` is not set. Can we use
+``expect`` here?
+
+.. code-block:: rust
+
+	#[expect(dead_code)]
+	fn g() {}
+
+	fn main() {
+	    #[cfg(CONFIG_X)]
+	    g();
+	}
+
+This would emit a lint if ``CONFIG_X`` is set, since it is not dead code in that
+configuration. Therefore, in cases like this, we cannot use ``expect`` as-is.
+
+A simple possibility is using ``allow``:
+
+.. code-block:: rust
+
+	#[allow(dead_code)]
+	fn g() {}
+
+	fn main() {
+	    #[cfg(CONFIG_X)]
+	    g();
+	}
+
+An alternative would be using a conditional ``expect``:
+
+.. code-block:: rust
+
+	#[cfg_attr(not(CONFIG_X), expect(dead_code))]
+	fn g() {}
+
+	fn main() {
+	    #[cfg(CONFIG_X)]
+	    g();
+	}
+
+This would ensure that, if someone introduces another call to ``g()`` somewhere
+(e.g. unconditionally), then it would be spotted that it is not dead code
+anymore. However, the ``cfg_attr`` is more complex than a simple ``allow``.
+
+Therefore, it is likely that it is not worth using conditional ``expect``\ s when
+more than one or two configurations are involved or when the lint may be
+triggered due to non-local changes (such as ``dead_code``).
+
+For more information about diagnostics in Rust, please see:
+
+	https://doc.rust-lang.org/stable/reference/attributes/diagnostics.html

MAINTAINERS

@@ -20234,6 +20234,7 @@ B:	https://github.com/Rust-for-Linux/linux/issues
 C:	zulip://rust-for-linux.zulipchat.com
 P:	https://rust-for-linux.com/contributing
 T:	git https://github.com/Rust-for-Linux/linux.git rust-next
+F:	.clippy.toml
 F:	Documentation/rust/
 F:	include/trace/events/rust_sample.h
 F:	rust/

Makefile

@@ -464,19 +464,23 @@ KBUILD_USERLDFLAGS := $(USERLDFLAGS)
 export rust_common_flags := --edition=2021 \
 			    -Zbinary_dep_depinfo=y \
 			    -Astable_features \
-			    -Dunsafe_op_in_unsafe_fn \
 			    -Dnon_ascii_idents \
+			    -Dunsafe_op_in_unsafe_fn \
+			    -Wmissing_docs \
 			    -Wrust_2018_idioms \
 			    -Wunreachable_pub \
-			    -Wmissing_docs \
-			    -Wrustdoc::missing_crate_level_docs \
 			    -Wclippy::all \
+			    -Wclippy::ignored_unit_patterns \
 			    -Wclippy::mut_mut \
 			    -Wclippy::needless_bitwise_bool \
 			    -Wclippy::needless_continue \
 			    -Aclippy::needless_lifetimes \
 			    -Wclippy::no_mangle_with_rust_abi \
-			    -Wclippy::dbg_macro
+			    -Wclippy::undocumented_unsafe_blocks \
+			    -Wclippy::unnecessary_safety_comment \
+			    -Wclippy::unnecessary_safety_doc \
+			    -Wrustdoc::missing_crate_level_docs \
+			    -Wrustdoc::unescaped_backticks
 
 KBUILD_HOSTCFLAGS   := $(KBUILD_USERHOSTCFLAGS) $(HOST_LFS_CFLAGS) \
 		       $(HOSTCFLAGS) -I $(srctree)/scripts/include
@@ -602,6 +606,9 @@ endif
 # Allows the usage of unstable features in stable compilers.
 export RUSTC_BOOTSTRAP := 1
 
+# Allows finding `.clippy.toml` in out-of-srctree builds.
+export CLIPPY_CONF_DIR := $(srctree)
+
 export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC HOSTPKG_CONFIG
 export RUSTC RUSTDOC RUSTFMT RUSTC_OR_CLIPPY_QUIET RUSTC_OR_CLIPPY BINDGEN
 export HOSTRUSTC KBUILD_HOSTRUSTFLAGS

drivers/block/rnull.rs

@@ -32,7 +32,7 @@ module! {
 }
 
 struct NullBlkModule {
-    _disk: Pin<Box<Mutex<GenDisk<NullBlkDevice>>>>,
+    _disk: Pin<KBox<Mutex<GenDisk<NullBlkDevice>>>>,
 }
 
 impl kernel::Module for NullBlkModule {
@@ -47,7 +47,7 @@ impl kernel::Module for NullBlkModule {
             .rotational(false)
             .build(format_args!("rnullb{}", 0), tagset)?;
 
-        let disk = Box::pin_init(new_mutex!(disk, "nullb:disk"), flags::GFP_KERNEL)?;
+        let disk = KBox::pin_init(new_mutex!(disk, "nullb:disk"), flags::GFP_KERNEL)?;
 
         Ok(Self { _disk: disk })
     }

mm/kasan/kasan_test_rust.rs

@@ -11,11 +11,12 @@ use kernel::prelude::*;
 /// drop the vector, and touch it.
 #[no_mangle]
 pub extern "C" fn kasan_test_rust_uaf() -> u8 {
-    let mut v: Vec<u8> = Vec::new();
+    let mut v: KVec<u8> = KVec::new();
     for _ in 0..4096 {
         v.push(0x42, GFP_KERNEL).unwrap();
     }
     let ptr: *mut u8 = addr_of_mut!(v[2048]);
     drop(v);
+    // SAFETY: Incorrect, on purpose.
     unsafe { *ptr }
 }

rust/Makefile

@@ -63,7 +63,7 @@ alloc-cfgs = \
 quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
       cmd_rustdoc = \
 	OBJTREE=$(abspath $(objtree)) \
-	$(RUSTDOC) $(if $(rustdoc_host),$(rust_common_flags),$(rust_flags)) \
+	$(RUSTDOC) $(filter-out $(skip_flags),$(if $(rustdoc_host),$(rust_common_flags),$(rust_flags))) \
 		$(rustc_target_flags) -L$(objtree)/$(obj) \
 		-Zunstable-options --generate-link-to-definition \
 		--output $(rustdoc_output) \
@@ -100,6 +100,9 @@ rustdoc-macros: private rustc_target_flags = --crate-type proc-macro \
 rustdoc-macros: $(src)/macros/lib.rs FORCE
 	+$(call if_changed,rustdoc)
 
+# Starting with Rust 1.82.0, skipping `-Wrustdoc::unescaped_backticks` should
+# not be needed -- see https://github.com/rust-lang/rust/pull/128307.
+rustdoc-core: private skip_flags = -Wrustdoc::unescaped_backticks
 rustdoc-core: private rustc_target_flags = $(core-cfgs)
 rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
 	+$(call if_changed,rustdoc)

rust/bindings/bindings_helper.h

@@ -49,6 +49,7 @@ const gfp_t RUST_CONST_HELPER_GFP_KERNEL_ACCOUNT = GFP_KERNEL_ACCOUNT;
 const gfp_t RUST_CONST_HELPER_GFP_NOWAIT = GFP_NOWAIT;
 const gfp_t RUST_CONST_HELPER___GFP_ZERO = __GFP_ZERO;
 const gfp_t RUST_CONST_HELPER___GFP_HIGHMEM = ___GFP_HIGHMEM;
+const gfp_t RUST_CONST_HELPER___GFP_NOWARN = ___GFP_NOWARN;
 const blk_features_t RUST_CONST_HELPER_BLK_FEAT_ROTATIONAL = BLK_FEAT_ROTATIONAL;
 
 #ifdef CONFIG_ASHMEM_RUST

rust/bindings/lib.rs

@@ -25,6 +25,7 @@
 )]
 
 #[allow(dead_code)]
+#[allow(clippy::undocumented_unsafe_blocks)]
 mod bindings_raw {
     // Use glob import here to expose all helpers.
     // Symbols defined within the module will take precedence to the glob import.

rust/helpers/helpers.c

@@ -29,5 +29,6 @@
 #include "spinlock.c"
 #include "task.c"
 #include "uaccess.c"
+#include "vmalloc.c"
 #include "wait.c"
 #include "workqueue.c"

rust/helpers/slab.c

@@ -7,3 +7,9 @@ rust_helper_krealloc(const void *objp, size_t new_size, gfp_t flags)
 {
 	return krealloc(objp, new_size, flags);
 }
+
+void * __must_check __realloc_size(2)
+rust_helper_kvrealloc(const void *p, size_t size, gfp_t flags)
+{
+	return kvrealloc(p, size, flags);
+}

rust/helpers/vmalloc.c

@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/vmalloc.h>
+
+void * __must_check __realloc_size(2)
+rust_helper_vrealloc(const void *p, size_t size, gfp_t flags)
+{
+	return vrealloc(p, size, flags);
+}

rust/kernel/alloc.rs

@@ -1,23 +1,41 @@
 // SPDX-License-Identifier: GPL-2.0
 
-//! Extensions to the [`alloc`] crate.
+//! Implementation of the kernel's memory allocation infrastructure.
 
-#[cfg(not(test))]
-#[cfg(not(testlib))]
-mod allocator;
-pub mod box_ext;
-pub mod vec_ext;
+#[cfg(not(any(test, testlib)))]
+pub mod allocator;
+pub mod kbox;
+pub mod kvec;
+pub mod layout;
+
+#[cfg(any(test, testlib))]
+pub mod allocator_test;
+
+#[cfg(any(test, testlib))]
+pub use self::allocator_test as allocator;
+
+pub use self::kbox::Box;
+pub use self::kbox::KBox;
+pub use self::kbox::KVBox;
+pub use self::kbox::VBox;
+
+pub use self::kvec::IntoIter;
+pub use self::kvec::KVVec;
+pub use self::kvec::KVec;
+pub use self::kvec::VVec;
+pub use self::kvec::Vec;
 
 /// Indicates an allocation error.
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub struct AllocError;
+use core::{alloc::Layout, ptr::NonNull};
 
 /// Flags to be used when allocating memory.
 ///
 /// They can be combined with the operators `|`, `&`, and `!`.
 ///
 /// Values can be used from the [`flags`] module.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, PartialEq)]
 pub struct Flags(u32);
 
 impl Flags {
@@ -25,6 +43,11 @@ impl Flags {
     pub(crate) fn as_raw(self) -> u32 {
         self.0
     }
+
+    /// Check whether `flags` is contained in `self`.
+    pub fn contains(self, flags: Flags) -> bool {
+        (self & flags) == flags
+    }
 }
 
 impl core::ops::BitOr for Flags {
@@ -85,4 +108,117 @@ pub mod flags {
     /// use any filesystem callback.  It is very likely to fail to allocate memory, even for very
     /// small allocations.
     pub const GFP_NOWAIT: Flags = Flags(bindings::GFP_NOWAIT);
+
+    /// Suppresses allocation failure reports.
+    ///
+    /// This is normally or'd with other flags.
+    pub const __GFP_NOWARN: Flags = Flags(bindings::__GFP_NOWARN);
+}
+
+/// The kernel's [`Allocator`] trait.
+///
+/// An implementation of [`Allocator`] can allocate, re-allocate and free memory buffers described
+/// via [`Layout`].
+///
+/// [`Allocator`] is designed to be implemented as a ZST; [`Allocator`] functions do not operate on
+/// an object instance.
+///
+/// In order to be able to support `#[derive(SmartPointer)]` later on, we need to avoid a design
+/// that requires an `Allocator` to be instantiated, hence its functions must not contain any kind
+/// of `self` parameter.
+///
+/// # Safety
+///
+/// - A memory allocation returned from an allocator must remain valid until it is explicitly freed.
+///
+/// - Any pointer to a valid memory allocation must be valid to be passed to any other [`Allocator`]
+///   function of the same type.
+///
+/// - Implementers must ensure that all trait functions abide by the guarantees documented in the
+///   `# Guarantees` sections.
+pub unsafe trait Allocator {
+    /// Allocate memory based on `layout` and `flags`.
+    ///
+    /// On success, returns a buffer represented as `NonNull<[u8]>` that satisfies the layout
+    /// constraints (i.e. minimum size and alignment as specified by `layout`).
+    ///
+    /// This function is equivalent to `realloc` when called with `None`.
+    ///
+    /// # Guarantees
+    ///
+    /// When the return value is `Ok(ptr)`, then `ptr` is
+    /// - valid for reads and writes for `layout.size()` bytes, until it is passed to
+    ///   [`Allocator::free`] or [`Allocator::realloc`],
+    /// - aligned to `layout.align()`,
+    ///
+    /// Additionally, `Flags` are honored as documented in
+    /// <https://docs.kernel.org/core-api/mm-api.html#mm-api-gfp-flags>.
+    fn alloc(layout: Layout, flags: Flags) -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: Passing `None` to `realloc` is valid by its safety requirements and asks for a
+        // new memory allocation.
+        unsafe { Self::realloc(None, layout, Layout::new::<()>(), flags) }
+    }
+
+    /// Re-allocate an existing memory allocation to satisfy the requested `layout`.
+    ///
+    /// If the requested size is zero, `realloc` behaves equivalent to `free`.
+    ///
+    /// If the requested size is larger than the size of the existing allocation, a successful call
+    /// to `realloc` guarantees that the new or grown buffer has at least `Layout::size` bytes, but
+    /// may also be larger.
+    ///
+    /// If the requested size is smaller than the size of the existing allocation, `realloc` may or
+    /// may not shrink the buffer; this is implementation specific to the allocator.
+    ///
+    /// On allocation failure, the existing buffer, if any, remains valid.
+    ///
+    /// The buffer is represented as `NonNull<[u8]>`.
+    ///
+    /// # Safety
+    ///
+    /// - If `ptr == Some(p)`, then `p` must point to an existing and valid memory allocation
+    ///   created by this [`Allocator`]; if `old_layout` is zero-sized `p` does not need to be a
+    ///   pointer returned by this [`Allocator`].
+    /// - `ptr` is allowed to be `None`; in this case a new memory allocation is created and
+    ///   `old_layout` is ignored.
+    /// - `old_layout` must match the `Layout` the allocation has been created with.
+    ///
+    /// # Guarantees
+    ///
+    /// This function has the same guarantees as [`Allocator::alloc`]. When `ptr == Some(p)`, then
+    /// it additionally guarantees that:
+    /// - the contents of the memory pointed to by `p` are preserved up to the lesser of the new
+    ///   and old size, i.e. `ret_ptr[0..min(layout.size(), old_layout.size())] ==
+    ///   p[0..min(layout.size(), old_layout.size())]`.
+    /// - when the return value is `Err(AllocError)`, then `ptr` is still valid.
+    unsafe fn realloc(
+        ptr: Option<NonNull<u8>>,
+        layout: Layout,
+        old_layout: Layout,
+        flags: Flags,
+    ) -> Result<NonNull<[u8]>, AllocError>;
+
+    /// Free an existing memory allocation.
+    ///
+    /// # Safety
+    ///
+    /// - `ptr` must point to an existing and valid memory allocation created by this [`Allocator`];
+    ///   if `old_layout` is zero-sized `p` does not need to be a pointer returned by this
+    ///   [`Allocator`].
+    /// - `layout` must match the `Layout` the allocation has been created with.
+    /// - The memory allocation at `ptr` must never again be read from or written to.
+    unsafe fn free(ptr: NonNull<u8>, layout: Layout) {
+        // SAFETY: The caller guarantees that `ptr` points at a valid allocation created by this
+        // allocator. We are passing a `Layout` with the smallest possible alignment, so it is
+        // smaller than or equal to the alignment previously used with this allocation.
+        let _ = unsafe { Self::realloc(Some(ptr), Layout::new::<()>(), layout, Flags(0)) };
+    }
+}
+
+/// Returns a properly aligned dangling pointer from the given `layout`.
+pub(crate) fn dangling_from_layout(layout: Layout) -> NonNull<u8> {
+    let ptr = layout.align() as *mut u8;
+
+    // SAFETY: `layout.align()` (and hence `ptr`) is guaranteed to be non-zero.
+    unsafe { NonNull::new_unchecked(ptr) }
 }

rust/kernel/alloc/allocator.rs

@@ -1,12 +1,58 @@
 // SPDX-License-Identifier: GPL-2.0
 
 //! Allocator support.
+//!
+//! Documentation for the kernel's memory allocators can found in the "Memory Allocation Guide"
+//! linked below. For instance, this includes the concept of "get free page" (GFP) flags and the
+//! typical application of the different kernel allocators.
+//!
+//! Reference: <https://docs.kernel.org/core-api/memory-allocation.html>
 
 use super::{flags::*, Flags};
 use core::alloc::{GlobalAlloc, Layout};
 use core::ptr;
+use core::ptr::NonNull;
 
-struct KernelAllocator;
+use crate::alloc::{AllocError, Allocator};
+use crate::bindings;
+use crate::pr_warn;
+
+/// The contiguous kernel allocator.
+///
+/// `Kmalloc` is typically used for physically contiguous allocations up to page size, but also
+/// supports larger allocations up to `bindings::KMALLOC_MAX_SIZE`, which is hardware specific.
+///
+/// For more details see [self].
+pub struct Kmalloc;
+
+/// The virtually contiguous kernel allocator.
+///
+/// `Vmalloc` allocates pages from the page level allocator and maps them into the contiguous kernel
+/// virtual space. It is typically used for large allocations. The memory allocated with this
+/// allocator is not physically contiguous.
+///
+/// For more details see [self].
+pub struct Vmalloc;
+
+/// The kvmalloc kernel allocator.
+///
+/// `KVmalloc` attempts to allocate memory with `Kmalloc` first, but falls back to `Vmalloc` upon
+/// failure. This allocator is typically used when the size for the requested allocation is not
+/// known and may exceed the capabilities of `Kmalloc`.
+///
+/// For more details see [self].
+pub struct KVmalloc;
+
+/// Returns a proper size to alloc a new object aligned to `new_layout`'s alignment.
+fn aligned_size(new_layout: Layout) -> usize {
+    // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
+    let layout = new_layout.pad_to_align();
+
+    // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()`
+    // which together with the slab guarantees means the `krealloc` will return a properly aligned
+    // object (see comments in `kmalloc()` for more information).
+    layout.size()
+}
 
 /// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment.
 ///
@@ -15,13 +61,7 @@ struct KernelAllocator;
 /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
 /// - `new_layout` must have a non-zero size.
 pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 {
-    // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
-    let layout = new_layout.pad_to_align();
-
-    // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()`
-    // which together with the slab guarantees means the `krealloc` will return a properly aligned
-    // object (see comments in `kmalloc()` for more information).
-    let size = layout.size();
+    let size = aligned_size(new_layout);
 
     // SAFETY:
     // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the
@@ -31,7 +71,93 @@ pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: F
     unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 }
 }
 
-unsafe impl GlobalAlloc for KernelAllocator {
+/// # Invariants
+///
+/// One of the following: `krealloc`, `vrealloc`, `kvrealloc`.
+struct ReallocFunc(
+    unsafe extern "C" fn(*const core::ffi::c_void, usize, u32) -> *mut core::ffi::c_void,
+);
+
+impl ReallocFunc {
+    // INVARIANT: `krealloc` satisfies the type invariants.
+    const KREALLOC: Self = Self(bindings::krealloc);
+
+    // INVARIANT: `vrealloc` satisfies the type invariants.
+    const VREALLOC: Self = Self(bindings::vrealloc);
+
+    // INVARIANT: `kvrealloc` satisfies the type invariants.
+    const KVREALLOC: Self = Self(bindings::kvrealloc);
+
+    /// # Safety
+    ///
+    /// This method has the same safety requirements as [`Allocator::realloc`].
+    ///
+    /// # Guarantees
+    ///
+    /// This method has the same guarantees as `Allocator::realloc`. Additionally
+    /// - it accepts any pointer to a valid memory allocation allocated by this function.
+    /// - memory allocated by this function remains valid until it is passed to this function.
+    unsafe fn call(
+        &self,
+        ptr: Option<NonNull<u8>>,
+        layout: Layout,
+        old_layout: Layout,
+        flags: Flags,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        let size = aligned_size(layout);
+        let ptr = match ptr {
+            Some(ptr) => {
+                if old_layout.size() == 0 {
+                    ptr::null()
+                } else {
+                    ptr.as_ptr()
+                }
+            }
+            None => ptr::null(),
+        };
+
+        // SAFETY:
+        // - `self.0` is one of `krealloc`, `vrealloc`, `kvrealloc` and thus only requires that
+        //   `ptr` is NULL or valid.
+        // - `ptr` is either NULL or valid by the safety requirements of this function.
+        //
+        // GUARANTEE:
+        // - `self.0` is one of `krealloc`, `vrealloc`, `kvrealloc`.
+        // - Those functions provide the guarantees of this function.
+        let raw_ptr = unsafe {
+            // If `size == 0` and `ptr != NULL` the memory behind the pointer is freed.
+            self.0(ptr.cast(), size, flags.0).cast()
+        };
+
+        let ptr = if size == 0 {
+            crate::alloc::dangling_from_layout(layout)
+        } else {
+            NonNull::new(raw_ptr).ok_or(AllocError)?
+        };
+
+        Ok(NonNull::slice_from_raw_parts(ptr, size))
+    }
+}
+
+// SAFETY: `realloc` delegates to `ReallocFunc::call`, which guarantees that
+// - memory remains valid until it is explicitly freed,
+// - passing a pointer to a valid memory allocation is OK,
+// - `realloc` satisfies the guarantees, since `ReallocFunc::call` has the same.
+unsafe impl Allocator for Kmalloc {
+    #[inline]
+    unsafe fn realloc(
+        ptr: Option<NonNull<u8>>,
+        layout: Layout,
+        old_layout: Layout,
+        flags: Flags,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: `ReallocFunc::call` has the same safety requirements as `Allocator::realloc`.
+        unsafe { ReallocFunc::KREALLOC.call(ptr, layout, old_layout, flags) }
+    }
+}
+
+// SAFETY: TODO.
+unsafe impl GlobalAlloc for Kmalloc {
     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
         // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
         // requirement.
@@ -39,6 +165,7 @@ unsafe impl GlobalAlloc for KernelAllocator {
     }
 
     unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+        // SAFETY: TODO.
         unsafe {
             bindings::kfree(ptr as *const core::ffi::c_void);
         }
@@ -66,8 +193,56 @@ unsafe impl GlobalAlloc for KernelAllocator {
     }
 }
 
+// SAFETY: `realloc` delegates to `ReallocFunc::call`, which guarantees that
+// - memory remains valid until it is explicitly freed,
+// - passing a pointer to a valid memory allocation is OK,
+// - `realloc` satisfies the guarantees, since `ReallocFunc::call` has the same.
+unsafe impl Allocator for Vmalloc {
+    #[inline]
+    unsafe fn realloc(
+        ptr: Option<NonNull<u8>>,
+        layout: Layout,
+        old_layout: Layout,
+        flags: Flags,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // TODO: Support alignments larger than PAGE_SIZE.
+        if layout.align() > bindings::PAGE_SIZE {
+            pr_warn!("Vmalloc does not support alignments larger than PAGE_SIZE yet.\n");
+            return Err(AllocError);
+        }
+
+        // SAFETY: If not `None`, `ptr` is guaranteed to point to valid memory, which was previously
+        // allocated with this `Allocator`.
+        unsafe { ReallocFunc::VREALLOC.call(ptr, layout, old_layout, flags) }
+    }
+}
+
+// SAFETY: `realloc` delegates to `ReallocFunc::call`, which guarantees that
+// - memory remains valid until it is explicitly freed,
+// - passing a pointer to a valid memory allocation is OK,
+// - `realloc` satisfies the guarantees, since `ReallocFunc::call` has the same.
+unsafe impl Allocator for KVmalloc {
+    #[inline]
+    unsafe fn realloc(
+        ptr: Option<NonNull<u8>>,
+        layout: Layout,
+        old_layout: Layout,
+        flags: Flags,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // TODO: Support alignments larger than PAGE_SIZE.
+        if layout.align() > bindings::PAGE_SIZE {
+            pr_warn!("KVmalloc does not support alignments larger than PAGE_SIZE yet.\n");
+            return Err(AllocError);
+        }
+
+        // SAFETY: If not `None`, `ptr` is guaranteed to point to valid memory, which was previously
+        // allocated with this `Allocator`.
+        unsafe { ReallocFunc::KVREALLOC.call(ptr, layout, old_layout, flags) }
+    }
+}
+
 #[global_allocator]
-static ALLOCATOR: KernelAllocator = KernelAllocator;
+static ALLOCATOR: Kmalloc = Kmalloc;
 
 // See <https://github.com/rust-lang/rust/pull/86844>.
 #[no_mangle]

rust/kernel/alloc/allocator_test.rs

@@ -0,0 +1,95 @@
+// 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 core::ffi::c_void;
+
+    #[link_name = "free"]
+    fn libc_free(ptr: *mut core::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,
+            ));
+        }
+
+        // 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()) } as *mut 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()))
+    }
+}

rust/kernel/alloc/box_ext.rs

@@ -1,89 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-//! Extensions to [`Box`] for fallible allocations.
-
-use super::{AllocError, Flags};
-use alloc::boxed::Box;
-use core::{mem::MaybeUninit, ptr, result::Result};
-
-/// Extensions to [`Box`].
-pub trait BoxExt<T>: Sized {
-    /// Allocates a new box.
-    ///
-    /// The allocation may fail, in which case an error is returned.
-    fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
-
-    /// Allocates a new uninitialised box.
-    ///
-    /// The allocation may fail, in which case an error is returned.
-    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
-
-    /// Drops the contents, but keeps the allocation.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use kernel::alloc::{flags, box_ext::BoxExt};
-    /// let value = Box::new([0; 32], flags::GFP_KERNEL)?;
-    /// assert_eq!(*value, [0; 32]);
-    /// let mut value = Box::drop_contents(value);
-    /// // Now we can re-use `value`:
-    /// value.write([1; 32]);
-    /// // SAFETY: We just wrote to it.
-    /// let value = unsafe { value.assume_init() };
-    /// assert_eq!(*value, [1; 32]);
-    /// # Ok::<(), Error>(())
-    /// ```
-    fn drop_contents(this: Self) -> Box<MaybeUninit<T>>;
-}
-
-impl<T> BoxExt<T> for Box<T> {
-    fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
-        let mut b = <Self as BoxExt<_>>::new_uninit(flags)?;
-        b.write(x);
-        // SAFETY: We just wrote to it.
-        Ok(unsafe { b.assume_init() })
-    }
-
-    #[cfg(any(test, testlib))]
-    fn new_uninit(_flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
-        Ok(Box::new_uninit())
-    }
-
-    #[cfg(not(any(test, testlib)))]
-    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
-        let ptr = if core::mem::size_of::<MaybeUninit<T>>() == 0 {
-            core::ptr::NonNull::<_>::dangling().as_ptr()
-        } else {
-            let layout = core::alloc::Layout::new::<MaybeUninit<T>>();
-
-            // SAFETY: Memory is being allocated (first arg is null). The only other source of
-            // safety issues is sleeping on atomic context, which is addressed by klint. Lastly,
-            // the type is not a SZT (checked above).
-            let ptr =
-                unsafe { super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags) };
-            if ptr.is_null() {
-                return Err(AllocError);
-            }
-
-            ptr.cast::<MaybeUninit<T>>()
-        };
-
-        // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
-        // zero-sized types, we use `NonNull::dangling`.
-        Ok(unsafe { Box::from_raw(ptr) })
-    }
-
-    fn drop_contents(this: Self) -> Box<MaybeUninit<T>> {
-        let ptr = Box::into_raw(this);
-        // SAFETY: `ptr` is valid, because it came from `Box::into_raw`.
-        unsafe { ptr::drop_in_place(ptr) };
-
-        // CAST: `MaybeUninit<T>` is a transparent wrapper of `T`.
-        let ptr = ptr.cast::<MaybeUninit<T>>();
-
-        // SAFETY: `ptr` is valid for writes, because it came from `Box::into_raw` and it is valid for
-        // reads, since the pointer came from `Box::into_raw` and the type is `MaybeUninit<T>`.
-        unsafe { Box::from_raw(ptr) }
-    }
-}

rust/kernel/alloc/kbox.rs

@@ -0,0 +1,456 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Implementation of [`Box`].
+
+#[allow(unused_imports)] // Used in doc comments.
+use super::allocator::{KVmalloc, Kmalloc, Vmalloc};
+use super::{AllocError, Allocator, Flags};
+use core::alloc::Layout;
+use core::fmt;
+use core::marker::PhantomData;
+use core::mem::ManuallyDrop;
+use core::mem::MaybeUninit;
+use core::ops::{Deref, DerefMut};
+use core::pin::Pin;
+use core::ptr::NonNull;
+use core::result::Result;
+
+use crate::init::{InPlaceInit, InPlaceWrite, Init, PinInit};
+use crate::types::ForeignOwnable;
+
+/// The kernel's [`Box`] type -- a heap allocation for a single value of type `T`.
+///
+/// This is the kernel's version of the Rust stdlib's `Box`. There are several differences,
+/// for example no `noalias` attribute is emitted and partially moving out of a `Box` is not
+/// supported. There are also several API differences, e.g. `Box` always requires an [`Allocator`]
+/// implementation to be passed as generic, page [`Flags`] when allocating memory and all functions
+/// that may allocate memory are fallible.
+///
+/// `Box` works with any of the kernel's allocators, e.g. [`Kmalloc`], [`Vmalloc`] or [`KVmalloc`].
+/// There are aliases for `Box` with these allocators ([`KBox`], [`VBox`], [`KVBox`]).
+///
+/// When dropping a [`Box`], the value is also dropped and the heap memory is automatically freed.
+///
+/// # Examples
+///
+/// ```
+/// let b = KBox::<u64>::new(24_u64, GFP_KERNEL)?;
+///
+/// assert_eq!(*b, 24_u64);
+/// # Ok::<(), Error>(())
+/// ```
+///
+/// ```
+/// # use kernel::bindings;
+/// const SIZE: usize = bindings::KMALLOC_MAX_SIZE as usize + 1;
+/// struct Huge([u8; SIZE]);
+///
+/// assert!(KBox::<Huge>::new_uninit(GFP_KERNEL | __GFP_NOWARN).is_err());
+/// ```
+///
+/// ```
+/// # use kernel::bindings;
+/// const SIZE: usize = bindings::KMALLOC_MAX_SIZE as usize + 1;
+/// struct Huge([u8; SIZE]);
+///
+/// assert!(KVBox::<Huge>::new_uninit(GFP_KERNEL).is_ok());
+/// ```
+///
+/// # Invariants
+///
+/// `self.0` is always properly aligned and either points to memory allocated with `A` or, for
+/// zero-sized types, is a dangling, well aligned pointer.
+#[repr(transparent)]
+pub struct Box<T: ?Sized, A: Allocator>(NonNull<T>, PhantomData<A>);
+
+/// Type alias for [`Box`] with a [`Kmalloc`] allocator.
+///
+/// # Examples
+///
+/// ```
+/// let b = KBox::new(24_u64, GFP_KERNEL)?;
+///
+/// assert_eq!(*b, 24_u64);
+/// # Ok::<(), Error>(())
+/// ```
+pub type KBox<T> = Box<T, super::allocator::Kmalloc>;
+
+/// Type alias for [`Box`] with a [`Vmalloc`] allocator.
+///
+/// # Examples
+///
+/// ```
+/// let b = VBox::new(24_u64, GFP_KERNEL)?;
+///
+/// assert_eq!(*b, 24_u64);
+/// # Ok::<(), Error>(())
+/// ```
+pub type VBox<T> = Box<T, super::allocator::Vmalloc>;
+
+/// Type alias for [`Box`] with a [`KVmalloc`] allocator.
+///
+/// # Examples
+///
+/// ```
+/// let b = KVBox::new(24_u64, GFP_KERNEL)?;
+///
+/// assert_eq!(*b, 24_u64);
+/// # Ok::<(), Error>(())
+/// ```
+pub type KVBox<T> = Box<T, super::allocator::KVmalloc>;
+
+// SAFETY: `Box` is `Send` if `T` is `Send` because the `Box` owns a `T`.
+unsafe impl<T, A> Send for Box<T, A>
+where
+    T: Send + ?Sized,
+    A: Allocator,
+{
+}
+
+// SAFETY: `Box` is `Sync` if `T` is `Sync` because the `Box` owns a `T`.
+unsafe impl<T, A> Sync for Box<T, A>
+where
+    T: Sync + ?Sized,
+    A: Allocator,
+{
+}
+
+impl<T, A> Box<T, A>
+where
+    T: ?Sized,
+    A: Allocator,
+{
+    /// Creates a new `Box<T, A>` from a raw pointer.
+    ///
+    /// # Safety
+    ///
+    /// For non-ZSTs, `raw` must point at an allocation allocated with `A` that is sufficiently
+    /// aligned for and holds a valid `T`. The caller passes ownership of the allocation to the
+    /// `Box`.
+    ///
+    /// For ZSTs, `raw` must be a dangling, well aligned pointer.
+    #[inline]
+    pub const unsafe fn from_raw(raw: *mut T) -> Self {
+        // INVARIANT: Validity of `raw` is guaranteed by the safety preconditions of this function.
+        // SAFETY: By the safety preconditions of this function, `raw` is not a NULL pointer.
+        Self(unsafe { NonNull::new_unchecked(raw) }, PhantomData)
+    }
+
+    /// Consumes the `Box<T, A>` and returns a raw pointer.
+    ///
+    /// This will not run the destructor of `T` and for non-ZSTs the allocation will stay alive
+    /// indefinitely. Use [`Box::from_raw`] to recover the [`Box`], drop the value and free the
+    /// allocation, if any.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let x = KBox::new(24, GFP_KERNEL)?;
+    /// let ptr = KBox::into_raw(x);
+    /// // SAFETY: `ptr` comes from a previous call to `KBox::into_raw`.
+    /// let x = unsafe { KBox::from_raw(ptr) };
+    ///
+    /// assert_eq!(*x, 24);
+    /// # Ok::<(), Error>(())
+    /// ```
+    #[inline]
+    pub fn into_raw(b: Self) -> *mut T {
+        ManuallyDrop::new(b).0.as_ptr()
+    }
+
+    /// Consumes and leaks the `Box<T, A>` and returns a mutable reference.
+    ///
+    /// See [`Box::into_raw`] for more details.
+    #[inline]
+    pub fn leak<'a>(b: Self) -> &'a mut T {
+        // SAFETY: `Box::into_raw` always returns a properly aligned and dereferenceable pointer
+        // which points to an initialized instance of `T`.
+        unsafe { &mut *Box::into_raw(b) }
+    }
+}
+
+impl<T, A> Box<MaybeUninit<T>, A>
+where
+    A: Allocator,
+{
+    /// Converts a `Box<MaybeUninit<T>, A>` to a `Box<T, A>`.
+    ///
+    /// It is undefined behavior to call this function while the value inside of `b` is not yet
+    /// fully initialized.
+    ///
+    /// # Safety
+    ///
+    /// Callers must ensure that the value inside of `b` is in an initialized state.
+    pub unsafe fn assume_init(self) -> Box<T, A> {
+        let raw = Self::into_raw(self);
+
+        // SAFETY: `raw` comes from a previous call to `Box::into_raw`. By the safety requirements
+        // of this function, the value inside the `Box` is in an initialized state. Hence, it is
+        // safe to reconstruct the `Box` as `Box<T, A>`.
+        unsafe { Box::from_raw(raw.cast()) }
+    }
+
+    /// Writes the value and converts to `Box<T, A>`.
+    pub fn write(mut self, value: T) -> Box<T, A> {
+        (*self).write(value);
+
+        // SAFETY: We've just initialized `b`'s value.
+        unsafe { self.assume_init() }
+    }
+}
+
+impl<T, A> Box<T, A>
+where
+    A: Allocator,
+{
+    /// Creates a new `Box<T, A>` and initializes its contents with `x`.
+    ///
+    /// New memory is allocated with `A`. The allocation may fail, in which case an error is
+    /// returned. For ZSTs no memory is allocated.
+    pub fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
+        let b = Self::new_uninit(flags)?;
+        Ok(Box::write(b, x))
+    }
+
+    /// Creates a new `Box<T, A>` with uninitialized contents.
+    ///
+    /// New memory is allocated with `A`. The allocation may fail, in which case an error is
+    /// returned. For ZSTs no memory is allocated.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let b = KBox::<u64>::new_uninit(GFP_KERNEL)?;
+    /// let b = KBox::write(b, 24);
+    ///
+    /// assert_eq!(*b, 24_u64);
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>, A>, AllocError> {
+        let layout = Layout::new::<MaybeUninit<T>>();
+        let ptr = A::alloc(layout, flags)?;
+
+        // INVARIANT: `ptr` is either a dangling pointer or points to memory allocated with `A`,
+        // which is sufficient in size and alignment for storing a `T`.
+        Ok(Box(ptr.cast(), PhantomData))
+    }
+
+    /// Constructs a new `Pin<Box<T, A>>`. If `T` does not implement [`Unpin`], then `x` will be
+    /// pinned in memory and can't be moved.
+    #[inline]
+    pub fn pin(x: T, flags: Flags) -> Result<Pin<Box<T, A>>, AllocError>
+    where
+        A: 'static,
+    {
+        Ok(Self::new(x, flags)?.into())
+    }
+
+    /// Forgets the contents (does not run the destructor), but keeps the allocation.
+    fn forget_contents(this: Self) -> Box<MaybeUninit<T>, A> {
+        let ptr = Self::into_raw(this);
+
+        // SAFETY: `ptr` is valid, because it came from `Box::into_raw`.
+        unsafe { Box::from_raw(ptr.cast()) }
+    }
+
+    /// Drops the contents, but keeps the allocation.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let value = KBox::new([0; 32], GFP_KERNEL)?;
+    /// assert_eq!(*value, [0; 32]);
+    /// let value = KBox::drop_contents(value);
+    /// // Now we can re-use `value`:
+    /// let value = KBox::write(value, [1; 32]);
+    /// assert_eq!(*value, [1; 32]);
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn drop_contents(this: Self) -> Box<MaybeUninit<T>, A> {
+        let ptr = this.0.as_ptr();
+
+        // SAFETY: `ptr` is valid, because it came from `this`. After this call we never access the
+        // value stored in `this` again.
+        unsafe { core::ptr::drop_in_place(ptr) };
+
+        Self::forget_contents(this)
+    }
+
+    /// Moves the `Box`'s value out of the `Box` and consumes the `Box`.
+    pub fn into_inner(b: Self) -> T {
+        // SAFETY: By the type invariant `&*b` is valid for `read`.
+        let value = unsafe { core::ptr::read(&*b) };
+        let _ = Self::forget_contents(b);
+        value
+    }
+}
+
+impl<T, A> From<Box<T, A>> for Pin<Box<T, A>>
+where
+    T: ?Sized,
+    A: Allocator,
+{
+    /// Converts a `Box<T, A>` into a `Pin<Box<T, A>>`. If `T` does not implement [`Unpin`], then
+    /// `*b` will be pinned in memory and can't be moved.
+    ///
+    /// This moves `b` into `Pin` without moving `*b` or allocating and copying any memory.
+    fn from(b: Box<T, A>) -> Self {
+        // SAFETY: The value wrapped inside a `Pin<Box<T, A>>` cannot be moved or replaced as long
+        // as `T` does not implement `Unpin`.
+        unsafe { Pin::new_unchecked(b) }
+    }
+}
+
+impl<T, A> InPlaceWrite<T> for Box<MaybeUninit<T>, A>
+where
+    A: Allocator + 'static,
+{
+    type Initialized = Box<T, A>;
+
+    fn write_init<E>(mut self, init: impl Init<T, E>) -> Result<Self::Initialized, E> {
+        let slot = self.as_mut_ptr();
+        // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
+        // slot is valid.
+        unsafe { init.__init(slot)? };
+        // SAFETY: All fields have been initialized.
+        Ok(unsafe { Box::assume_init(self) })
+    }
+
+    fn write_pin_init<E>(mut self, init: impl PinInit<T, E>) -> Result<Pin<Self::Initialized>, E> {
+        let slot = self.as_mut_ptr();
+        // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
+        // slot is valid and will not be moved, because we pin it later.
+        unsafe { init.__pinned_init(slot)? };
+        // SAFETY: All fields have been initialized.
+        Ok(unsafe { Box::assume_init(self) }.into())
+    }
+}
+
+impl<T, A> InPlaceInit<T> for Box<T, A>
+where
+    A: Allocator + 'static,
+{
+    type PinnedSelf = Pin<Self>;
+
+    #[inline]
+    fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Pin<Self>, E>
+    where
+        E: From<AllocError>,
+    {
+        Box::<_, A>::new_uninit(flags)?.write_pin_init(init)
+    }
+
+    #[inline]
+    fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
+    where
+        E: From<AllocError>,
+    {
+        Box::<_, A>::new_uninit(flags)?.write_init(init)
+    }
+}
+
+impl<T: 'static, A> ForeignOwnable for Box<T, A>
+where
+    A: Allocator,
+{
+    type Borrowed<'a> = &'a T;
+
+    fn into_foreign(self) -> *const core::ffi::c_void {
+        Box::into_raw(self) as _
+    }
+
+    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
+        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
+        // call to `Self::into_foreign`.
+        unsafe { Box::from_raw(ptr as _) }
+    }
+
+    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
+        // SAFETY: The safety requirements of this method ensure that the object remains alive and
+        // immutable for the duration of 'a.
+        unsafe { &*ptr.cast() }
+    }
+}
+
+impl<T: 'static, A> ForeignOwnable for Pin<Box<T, A>>
+where
+    A: Allocator,
+{
+    type Borrowed<'a> = Pin<&'a T>;
+
+    fn into_foreign(self) -> *const core::ffi::c_void {
+        // SAFETY: We are still treating the box as pinned.
+        Box::into_raw(unsafe { Pin::into_inner_unchecked(self) }) as _
+    }
+
+    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
+        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
+        // call to `Self::into_foreign`.
+        unsafe { Pin::new_unchecked(Box::from_raw(ptr as _)) }
+    }
+
+    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> Pin<&'a T> {
+        // SAFETY: The safety requirements for this function ensure that the object is still alive,
+        // so it is safe to dereference the raw pointer.
+        // The safety requirements of `from_foreign` also ensure that the object remains alive for
+        // the lifetime of the returned value.
+        let r = unsafe { &*ptr.cast() };
+
+        // SAFETY: This pointer originates from a `Pin<Box<T>>`.
+        unsafe { Pin::new_unchecked(r) }
+    }
+}
+
+impl<T, A> Deref for Box<T, A>
+where
+    T: ?Sized,
+    A: Allocator,
+{
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        // SAFETY: `self.0` is always properly aligned, dereferenceable and points to an initialized
+        // instance of `T`.
+        unsafe { self.0.as_ref() }
+    }
+}
+
+impl<T, A> DerefMut for Box<T, A>
+where
+    T: ?Sized,
+    A: Allocator,
+{
+    fn deref_mut(&mut self) -> &mut T {
+        // SAFETY: `self.0` is always properly aligned, dereferenceable and points to an initialized
+        // instance of `T`.
+        unsafe { self.0.as_mut() }
+    }
+}
+
+impl<T, A> fmt::Debug for Box<T, A>
+where
+    T: ?Sized + fmt::Debug,
+    A: Allocator,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&**self, f)
+    }
+}
+
+impl<T, A> Drop for Box<T, A>
+where
+    T: ?Sized,
+    A: Allocator,
+{
+    fn drop(&mut self) {
+        let layout = Layout::for_value::<T>(self);
+
+        // SAFETY: The pointer in `self.0` is guaranteed to be valid by the type invariant.
+        unsafe { core::ptr::drop_in_place::<T>(self.deref_mut()) };
+
+        // SAFETY:
+        // - `self.0` was previously allocated with `A`.
+        // - `layout` is equal to the `Layout´ `self.0` was allocated with.
+        unsafe { A::free(self.0.cast(), layout) };
+    }
+}

rust/kernel/alloc/kvec.rs

@@ -0,0 +1,913 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Implementation of [`Vec`].
+
+use super::{
+    allocator::{KVmalloc, Kmalloc, Vmalloc},
+    layout::ArrayLayout,
+    AllocError, Allocator, Box, Flags,
+};
+use core::{
+    fmt,
+    marker::PhantomData,
+    mem::{ManuallyDrop, MaybeUninit},
+    ops::Deref,
+    ops::DerefMut,
+    ops::Index,
+    ops::IndexMut,
+    ptr,
+    ptr::NonNull,
+    slice,
+    slice::SliceIndex,
+};
+
+/// Create a [`KVec`] containing the arguments.
+///
+/// New memory is allocated with `GFP_KERNEL`.
+///
+/// # Examples
+///
+/// ```
+/// let mut v = kernel::kvec![];
+/// v.push(1, GFP_KERNEL)?;
+/// assert_eq!(v, [1]);
+///
+/// let mut v = kernel::kvec![1; 3]?;
+/// v.push(4, GFP_KERNEL)?;
+/// assert_eq!(v, [1, 1, 1, 4]);
+///
+/// let mut v = kernel::kvec![1, 2, 3]?;
+/// v.push(4, GFP_KERNEL)?;
+/// assert_eq!(v, [1, 2, 3, 4]);
+///
+/// # Ok::<(), Error>(())
+/// ```
+#[macro_export]
+macro_rules! kvec {
+    () => (
+        $crate::alloc::KVec::new()
+    );
+    ($elem:expr; $n:expr) => (
+        $crate::alloc::KVec::from_elem($elem, $n, GFP_KERNEL)
+    );
+    ($($x:expr),+ $(,)?) => (
+        match $crate::alloc::KBox::new_uninit(GFP_KERNEL) {
+            Ok(b) => Ok($crate::alloc::KVec::from($crate::alloc::KBox::write(b, [$($x),+]))),
+            Err(e) => Err(e),
+        }
+    );
+}
+
+/// The kernel's [`Vec`] type.
+///
+/// A contiguous growable array type with contents allocated with the kernel's allocators (e.g.
+/// [`Kmalloc`], [`Vmalloc`] or [`KVmalloc`]), written `Vec<T, A>`.
+///
+/// For non-zero-sized values, a [`Vec`] will use the given allocator `A` for its allocation. For
+/// the most common allocators the type aliases [`KVec`], [`VVec`] and [`KVVec`] exist.
+///
+/// For zero-sized types the [`Vec`]'s pointer must be `dangling_mut::<T>`; no memory is allocated.
+///
+/// Generally, [`Vec`] consists of a pointer that represents the vector's backing buffer, the
+/// capacity of the vector (the number of elements that currently fit into the vector), its length
+/// (the number of elements that are currently stored in the vector) and the `Allocator` type used
+/// to allocate (and free) the backing buffer.
+///
+/// A [`Vec`] can be deconstructed into and (re-)constructed from its previously named raw parts
+/// and manually modified.
+///
+/// [`Vec`]'s backing buffer gets, if required, automatically increased (re-allocated) when elements
+/// are added to the vector.
+///
+/// # Invariants
+///
+/// - `self.ptr` is always properly aligned and either points to memory allocated with `A` or, for
+///   zero-sized types, is a dangling, well aligned pointer.
+///
+/// - `self.len` always represents the exact number of elements stored in the vector.
+///
+/// - `self.layout` represents the absolute number of elements that can be stored within the vector
+///   without re-allocation. For ZSTs `self.layout`'s capacity is zero. However, it is legal for the
+///   backing buffer to be larger than `layout`.
+///
+/// - The `Allocator` type `A` of the vector is the exact same `Allocator` type the backing buffer
+///   was allocated with (and must be freed with).
+pub struct Vec<T, A: Allocator> {
+    ptr: NonNull<T>,
+    /// Represents the actual buffer size as `cap` times `size_of::<T>` bytes.
+    ///
+    /// Note: This isn't quite the same as `Self::capacity`, which in contrast returns the number of
+    /// elements we can still store without reallocating.
+    layout: ArrayLayout<T>,
+    len: usize,
+    _p: PhantomData<A>,
+}
+
+/// Type alias for [`Vec`] with a [`Kmalloc`] allocator.
+///
+/// # Examples
+///
+/// ```
+/// let mut v = KVec::new();
+/// v.push(1, GFP_KERNEL)?;
+/// assert_eq!(&v, &[1]);
+///
+/// # Ok::<(), Error>(())
+/// ```
+pub type KVec<T> = Vec<T, Kmalloc>;
+
+/// Type alias for [`Vec`] with a [`Vmalloc`] allocator.
+///
+/// # Examples
+///
+/// ```
+/// let mut v = VVec::new();
+/// v.push(1, GFP_KERNEL)?;
+/// assert_eq!(&v, &[1]);
+///
+/// # Ok::<(), Error>(())
+/// ```
+pub type VVec<T> = Vec<T, Vmalloc>;
+
+/// Type alias for [`Vec`] with a [`KVmalloc`] allocator.
+///
+/// # Examples
+///
+/// ```
+/// let mut v = KVVec::new();
+/// v.push(1, GFP_KERNEL)?;
+/// assert_eq!(&v, &[1]);
+///
+/// # Ok::<(), Error>(())
+/// ```
+pub type KVVec<T> = Vec<T, KVmalloc>;
+
+// SAFETY: `Vec` is `Send` if `T` is `Send` because `Vec` owns its elements.
+unsafe impl<T, A> Send for Vec<T, A>
+where
+    T: Send,
+    A: Allocator,
+{
+}
+
+// SAFETY: `Vec` is `Sync` if `T` is `Sync` because `Vec` owns its elements.
+unsafe impl<T, A> Sync for Vec<T, A>
+where
+    T: Sync,
+    A: Allocator,
+{
+}
+
+impl<T, A> Vec<T, A>
+where
+    A: Allocator,
+{
+    #[inline]
+    const fn is_zst() -> bool {
+        core::mem::size_of::<T>() == 0
+    }
+
+    /// Returns the number of elements that can be stored within the vector without allocating
+    /// additional memory.
+    pub fn capacity(&self) -> usize {
+        if const { Self::is_zst() } {
+            usize::MAX
+        } else {
+            self.layout.len()
+        }
+    }
+
+    /// Returns the number of elements stored within the vector.
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.len
+    }
+
+    /// Forcefully sets `self.len` to `new_len`.
+    ///
+    /// # Safety
+    ///
+    /// - `new_len` must be less than or equal to [`Self::capacity`].
+    /// - If `new_len` is greater than `self.len`, all elements within the interval
+    ///   [`self.len`,`new_len`) must be initialized.
+    #[inline]
+    pub unsafe fn set_len(&mut self, new_len: usize) {
+        debug_assert!(new_len <= self.capacity());
+        self.len = new_len;
+    }
+
+    /// Returns a slice of the entire vector.
+    #[inline]
+    pub fn as_slice(&self) -> &[T] {
+        self
+    }
+
+    /// Returns a mutable slice of the entire vector.
+    #[inline]
+    pub fn as_mut_slice(&mut self) -> &mut [T] {
+        self
+    }
+
+    /// Returns a mutable raw pointer to the vector's backing buffer, or, if `T` is a ZST, a
+    /// dangling raw pointer.
+    #[inline]
+    pub fn as_mut_ptr(&mut self) -> *mut T {
+        self.ptr.as_ptr()
+    }
+
+    /// Returns a raw pointer to the vector's backing buffer, or, if `T` is a ZST, a dangling raw
+    /// pointer.
+    #[inline]
+    pub fn as_ptr(&self) -> *const T {
+        self.ptr.as_ptr()
+    }
+
+    /// Returns `true` if the vector contains no elements, `false` otherwise.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = KVec::new();
+    /// assert!(v.is_empty());
+    ///
+    /// v.push(1, GFP_KERNEL);
+    /// assert!(!v.is_empty());
+    /// ```
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// Creates a new, empty `Vec<T, A>`.
+    ///
+    /// This method does not allocate by itself.
+    #[inline]
+    pub const fn new() -> Self {
+        // INVARIANT: Since this is a new, empty `Vec` with no backing memory yet,
+        // - `ptr` is a properly aligned dangling pointer for type `T`,
+        // - `layout` is an empty `ArrayLayout` (zero capacity)
+        // - `len` is zero, since no elements can be or have been stored,
+        // - `A` is always valid.
+        Self {
+            ptr: NonNull::dangling(),
+            layout: ArrayLayout::empty(),
+            len: 0,
+            _p: PhantomData::<A>,
+        }
+    }
+
+    /// Returns a slice of `MaybeUninit<T>` for the remaining spare capacity of the vector.
+    pub fn spare_capacity_mut(&mut self) -> &mut [MaybeUninit<T>] {
+        // SAFETY:
+        // - `self.len` is smaller than `self.capacity` and hence, the resulting pointer is
+        //   guaranteed to be part of the same allocated object.
+        // - `self.len` can not overflow `isize`.
+        let ptr = unsafe { self.as_mut_ptr().add(self.len) } as *mut MaybeUninit<T>;
+
+        // SAFETY: The memory between `self.len` and `self.capacity` is guaranteed to be allocated
+        // and valid, but uninitialized.
+        unsafe { slice::from_raw_parts_mut(ptr, self.capacity() - self.len) }
+    }
+
+    /// Appends an element to the back of the [`Vec`] instance.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = KVec::new();
+    /// v.push(1, GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1]);
+    ///
+    /// v.push(2, GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1, 2]);
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> {
+        self.reserve(1, flags)?;
+
+        // SAFETY:
+        // - `self.len` is smaller than `self.capacity` and hence, the resulting pointer is
+        //   guaranteed to be part of the same allocated object.
+        // - `self.len` can not overflow `isize`.
+        let ptr = unsafe { self.as_mut_ptr().add(self.len) };
+
+        // SAFETY:
+        // - `ptr` is properly aligned and valid for writes.
+        unsafe { core::ptr::write(ptr, v) };
+
+        // SAFETY: We just initialised the first spare entry, so it is safe to increase the length
+        // by 1. We also know that the new length is <= capacity because of the previous call to
+        // `reserve` above.
+        unsafe { self.set_len(self.len() + 1) };
+        Ok(())
+    }
+
+    /// Creates a new [`Vec`] instance with at least the given capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let v = KVec::<u32>::with_capacity(20, GFP_KERNEL)?;
+    ///
+    /// assert!(v.capacity() >= 20);
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError> {
+        let mut v = Vec::new();
+
+        v.reserve(capacity, flags)?;
+
+        Ok(v)
+    }
+
+    /// Creates a `Vec<T, A>` from a pointer, a length and a capacity using the allocator `A`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = kernel::kvec![1, 2, 3]?;
+    /// v.reserve(1, GFP_KERNEL)?;
+    ///
+    /// let (mut ptr, mut len, cap) = v.into_raw_parts();
+    ///
+    /// // SAFETY: We've just reserved memory for another element.
+    /// unsafe { ptr.add(len).write(4) };
+    /// len += 1;
+    ///
+    /// // SAFETY: We only wrote an additional element at the end of the `KVec`'s buffer and
+    /// // correspondingly increased the length of the `KVec` by one. Otherwise, we construct it
+    /// // from the exact same raw parts.
+    /// let v = unsafe { KVec::from_raw_parts(ptr, len, cap) };
+    ///
+    /// assert_eq!(v, [1, 2, 3, 4]);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    ///
+    /// # Safety
+    ///
+    /// If `T` is a ZST:
+    ///
+    /// - `ptr` must be a dangling, well aligned pointer.
+    ///
+    /// Otherwise:
+    ///
+    /// - `ptr` must have been allocated with the allocator `A`.
+    /// - `ptr` must satisfy or exceed the alignment requirements of `T`.
+    /// - `ptr` must point to memory with a size of at least `size_of::<T>() * capacity` bytes.
+    /// - The allocated size in bytes must not be larger than `isize::MAX`.
+    /// - `length` must be less than or equal to `capacity`.
+    /// - The first `length` elements must be initialized values of type `T`.
+    ///
+    /// It is also valid to create an empty `Vec` passing a dangling pointer for `ptr` and zero for
+    /// `cap` and `len`.
+    pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Self {
+        let layout = if Self::is_zst() {
+            ArrayLayout::empty()
+        } else {
+            // SAFETY: By the safety requirements of this function, `capacity * size_of::<T>()` is
+            // smaller than `isize::MAX`.
+            unsafe { ArrayLayout::new_unchecked(capacity) }
+        };
+
+        // INVARIANT: For ZSTs, we store an empty `ArrayLayout`, all other type invariants are
+        // covered by the safety requirements of this function.
+        Self {
+            // SAFETY: By the safety requirements, `ptr` is either dangling or pointing to a valid
+            // memory allocation, allocated with `A`.
+            ptr: unsafe { NonNull::new_unchecked(ptr) },
+            layout,
+            len: length,
+            _p: PhantomData::<A>,
+        }
+    }
+
+    /// Consumes the `Vec<T, A>` and returns its raw components `pointer`, `length` and `capacity`.
+    ///
+    /// This will not run the destructor of the contained elements and for non-ZSTs the allocation
+    /// will stay alive indefinitely. Use [`Vec::from_raw_parts`] to recover the [`Vec`], drop the
+    /// elements and free the allocation, if any.
+    pub fn into_raw_parts(self) -> (*mut T, usize, usize) {
+        let mut me = ManuallyDrop::new(self);
+        let len = me.len();
+        let capacity = me.capacity();
+        let ptr = me.as_mut_ptr();
+        (ptr, len, capacity)
+    }
+
+    /// Ensures that the capacity exceeds the length by at least `additional` elements.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = KVec::new();
+    /// v.push(1, GFP_KERNEL)?;
+    ///
+    /// v.reserve(10, GFP_KERNEL)?;
+    /// let cap = v.capacity();
+    /// assert!(cap >= 10);
+    ///
+    /// v.reserve(10, GFP_KERNEL)?;
+    /// let new_cap = v.capacity();
+    /// assert_eq!(new_cap, cap);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError> {
+        let len = self.len();
+        let cap = self.capacity();
+
+        if cap - len >= additional {
+            return Ok(());
+        }
+
+        if Self::is_zst() {
+            // The capacity is already `usize::MAX` for ZSTs, we can't go higher.
+            return Err(AllocError);
+        }
+
+        // We know that `cap <= isize::MAX` because of the type invariants of `Self`. So the
+        // multiplication by two won't overflow.
+        let new_cap = core::cmp::max(cap * 2, len.checked_add(additional).ok_or(AllocError)?);
+        let layout = ArrayLayout::new(new_cap).map_err(|_| AllocError)?;
+
+        // SAFETY:
+        // - `ptr` is valid because it's either `None` or comes from a previous call to
+        //   `A::realloc`.
+        // - `self.layout` matches the `ArrayLayout` of the preceding allocation.
+        let ptr = unsafe {
+            A::realloc(
+                Some(self.ptr.cast()),
+                layout.into(),
+                self.layout.into(),
+                flags,
+            )?
+        };
+
+        // INVARIANT:
+        // - `layout` is some `ArrayLayout::<T>`,
+        // - `ptr` has been created by `A::realloc` from `layout`.
+        self.ptr = ptr.cast();
+        self.layout = layout;
+
+        Ok(())
+    }
+}
+
+impl<T: Clone, A: Allocator> Vec<T, A> {
+    /// Extend the vector by `n` clones of `value`.
+    pub fn extend_with(&mut self, n: usize, value: T, flags: Flags) -> Result<(), AllocError> {
+        if n == 0 {
+            return Ok(());
+        }
+
+        self.reserve(n, flags)?;
+
+        let spare = self.spare_capacity_mut();
+
+        for item in spare.iter_mut().take(n - 1) {
+            item.write(value.clone());
+        }
+
+        // We can write the last element directly without cloning needlessly.
+        spare[n - 1].write(value);
+
+        // SAFETY:
+        // - `self.len() + n < self.capacity()` due to the call to reserve above,
+        // - the loop and the line above initialized the next `n` elements.
+        unsafe { self.set_len(self.len() + n) };
+
+        Ok(())
+    }
+
+    /// Pushes clones of the elements of slice into the [`Vec`] instance.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = KVec::new();
+    /// v.push(1, GFP_KERNEL)?;
+    ///
+    /// v.extend_from_slice(&[20, 30, 40], GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1, 20, 30, 40]);
+    ///
+    /// v.extend_from_slice(&[50, 60], GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1, 20, 30, 40, 50, 60]);
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError> {
+        self.reserve(other.len(), flags)?;
+        for (slot, item) in core::iter::zip(self.spare_capacity_mut(), other) {
+            slot.write(item.clone());
+        }
+
+        // SAFETY:
+        // - `other.len()` spare entries have just been initialized, so it is safe to increase
+        //   the length by the same number.
+        // - `self.len() + other.len() <= self.capacity()` is guaranteed by the preceding `reserve`
+        //   call.
+        unsafe { self.set_len(self.len() + other.len()) };
+        Ok(())
+    }
+
+    /// Create a new `Vec<T, A>` and extend it by `n` clones of `value`.
+    pub fn from_elem(value: T, n: usize, flags: Flags) -> Result<Self, AllocError> {
+        let mut v = Self::with_capacity(n, flags)?;
+
+        v.extend_with(n, value, flags)?;
+
+        Ok(v)
+    }
+}
+
+impl<T, A> Drop for Vec<T, A>
+where
+    A: Allocator,
+{
+    fn drop(&mut self) {
+        // SAFETY: `self.as_mut_ptr` is guaranteed to be valid by the type invariant.
+        unsafe {
+            ptr::drop_in_place(core::ptr::slice_from_raw_parts_mut(
+                self.as_mut_ptr(),
+                self.len,
+            ))
+        };
+
+        // SAFETY:
+        // - `self.ptr` was previously allocated with `A`.
+        // - `self.layout` matches the `ArrayLayout` of the preceding allocation.
+        unsafe { A::free(self.ptr.cast(), self.layout.into()) };
+    }
+}
+
+impl<T, A, const N: usize> From<Box<[T; N], A>> for Vec<T, A>
+where
+    A: Allocator,
+{
+    fn from(b: Box<[T; N], A>) -> Vec<T, A> {
+        let len = b.len();
+        let ptr = Box::into_raw(b);
+
+        // SAFETY:
+        // - `b` has been allocated with `A`,
+        // - `ptr` fulfills the alignment requirements for `T`,
+        // - `ptr` points to memory with at least a size of `size_of::<T>() * len`,
+        // - all elements within `b` are initialized values of `T`,
+        // - `len` does not exceed `isize::MAX`.
+        unsafe { Vec::from_raw_parts(ptr as _, len, len) }
+    }
+}
+
+impl<T> Default for KVec<T> {
+    #[inline]
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T: fmt::Debug, A: Allocator> fmt::Debug for Vec<T, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&**self, f)
+    }
+}
+
+impl<T, A> Deref for Vec<T, A>
+where
+    A: Allocator,
+{
+    type Target = [T];
+
+    #[inline]
+    fn deref(&self) -> &[T] {
+        // SAFETY: The memory behind `self.as_ptr()` is guaranteed to contain `self.len`
+        // initialized elements of type `T`.
+        unsafe { slice::from_raw_parts(self.as_ptr(), self.len) }
+    }
+}
+
+impl<T, A> DerefMut for Vec<T, A>
+where
+    A: Allocator,
+{
+    #[inline]
+    fn deref_mut(&mut self) -> &mut [T] {
+        // SAFETY: The memory behind `self.as_ptr()` is guaranteed to contain `self.len`
+        // initialized elements of type `T`.
+        unsafe { slice::from_raw_parts_mut(self.as_mut_ptr(), self.len) }
+    }
+}
+
+impl<T: Eq, A> Eq for Vec<T, A> where A: Allocator {}
+
+impl<T, I: SliceIndex<[T]>, A> Index<I> for Vec<T, A>
+where
+    A: Allocator,
+{
+    type Output = I::Output;
+
+    #[inline]
+    fn index(&self, index: I) -> &Self::Output {
+        Index::index(&**self, index)
+    }
+}
+
+impl<T, I: SliceIndex<[T]>, A> IndexMut<I> for Vec<T, A>
+where
+    A: Allocator,
+{
+    #[inline]
+    fn index_mut(&mut self, index: I) -> &mut Self::Output {
+        IndexMut::index_mut(&mut **self, index)
+    }
+}
+
+macro_rules! impl_slice_eq {
+    ($([$($vars:tt)*] $lhs:ty, $rhs:ty,)*) => {
+        $(
+            impl<T, U, $($vars)*> PartialEq<$rhs> for $lhs
+            where
+                T: PartialEq<U>,
+            {
+                #[inline]
+                fn eq(&self, other: &$rhs) -> bool { self[..] == other[..] }
+            }
+        )*
+    }
+}
+
+impl_slice_eq! {
+    [A1: Allocator, A2: Allocator] Vec<T, A1>, Vec<U, A2>,
+    [A: Allocator] Vec<T, A>, &[U],
+    [A: Allocator] Vec<T, A>, &mut [U],
+    [A: Allocator] &[T], Vec<U, A>,
+    [A: Allocator] &mut [T], Vec<U, A>,
+    [A: Allocator] Vec<T, A>, [U],
+    [A: Allocator] [T], Vec<U, A>,
+    [A: Allocator, const N: usize] Vec<T, A>, [U; N],
+    [A: Allocator, const N: usize] Vec<T, A>, &[U; N],
+}
+
+impl<'a, T, A> IntoIterator for &'a Vec<T, A>
+where
+    A: Allocator,
+{
+    type Item = &'a T;
+    type IntoIter = slice::Iter<'a, T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
+impl<'a, T, A: Allocator> IntoIterator for &'a mut Vec<T, A>
+where
+    A: Allocator,
+{
+    type Item = &'a mut T;
+    type IntoIter = slice::IterMut<'a, T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter_mut()
+    }
+}
+
+/// An [`Iterator`] implementation for [`Vec`] that moves elements out of a vector.
+///
+/// This structure is created by the [`Vec::into_iter`] method on [`Vec`] (provided by the
+/// [`IntoIterator`] trait).
+///
+/// # Examples
+///
+/// ```
+/// let v = kernel::kvec![0, 1, 2]?;
+/// let iter = v.into_iter();
+///
+/// # Ok::<(), Error>(())
+/// ```
+pub struct IntoIter<T, A: Allocator> {
+    ptr: *mut T,
+    buf: NonNull<T>,
+    len: usize,
+    layout: ArrayLayout<T>,
+    _p: PhantomData<A>,
+}
+
+impl<T, A> IntoIter<T, A>
+where
+    A: Allocator,
+{
+    fn into_raw_parts(self) -> (*mut T, NonNull<T>, usize, usize) {
+        let me = ManuallyDrop::new(self);
+        let ptr = me.ptr;
+        let buf = me.buf;
+        let len = me.len;
+        let cap = me.layout.len();
+        (ptr, buf, len, cap)
+    }
+
+    /// Same as `Iterator::collect` but specialized for `Vec`'s `IntoIter`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let v = kernel::kvec![1, 2, 3]?;
+    /// let mut it = v.into_iter();
+    ///
+    /// assert_eq!(it.next(), Some(1));
+    ///
+    /// let v = it.collect(GFP_KERNEL);
+    /// assert_eq!(v, [2, 3]);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    ///
+    /// # Implementation details
+    ///
+    /// Currently, we can't implement `FromIterator`. There are a couple of issues with this trait
+    /// in the kernel, namely:
+    ///
+    /// - Rust's specialization feature is unstable. This prevents us to optimize for the special
+    ///   case where `I::IntoIter` equals `Vec`'s `IntoIter` type.
+    /// - We also can't use `I::IntoIter`'s type ID either to work around this, since `FromIterator`
+    ///   doesn't require this type to be `'static`.
+    /// - `FromIterator::from_iter` does return `Self` instead of `Result<Self, AllocError>`, hence
+    ///   we can't properly handle allocation failures.
+    /// - Neither `Iterator::collect` nor `FromIterator::from_iter` can handle additional allocation
+    ///   flags.
+    ///
+    /// Instead, provide `IntoIter::collect`, such that we can at least convert a `IntoIter` into a
+    /// `Vec` again.
+    ///
+    /// Note that `IntoIter::collect` doesn't require `Flags`, since it re-uses the existing backing
+    /// buffer. However, this backing buffer may be shrunk to the actual count of elements.
+    pub fn collect(self, flags: Flags) -> Vec<T, A> {
+        let old_layout = self.layout;
+        let (mut ptr, buf, len, mut cap) = self.into_raw_parts();
+        let has_advanced = ptr != buf.as_ptr();
+
+        if has_advanced {
+            // Copy the contents we have advanced to at the beginning of the buffer.
+            //
+            // SAFETY:
+            // - `ptr` is valid for reads of `len * size_of::<T>()` bytes,
+            // - `buf.as_ptr()` is valid for writes of `len * size_of::<T>()` bytes,
+            // - `ptr` and `buf.as_ptr()` are not be subject to aliasing restrictions relative to
+            //   each other,
+            // - both `ptr` and `buf.ptr()` are properly aligned.
+            unsafe { ptr::copy(ptr, buf.as_ptr(), len) };
+            ptr = buf.as_ptr();
+
+            // SAFETY: `len` is guaranteed to be smaller than `self.layout.len()`.
+            let layout = unsafe { ArrayLayout::<T>::new_unchecked(len) };
+
+            // SAFETY: `buf` points to the start of the backing buffer and `len` is guaranteed to be
+            // smaller than `cap`. Depending on `alloc` this operation may shrink the buffer or leaves
+            // it as it is.
+            ptr = match unsafe {
+                A::realloc(Some(buf.cast()), layout.into(), old_layout.into(), flags)
+            } {
+                // If we fail to shrink, which likely can't even happen, continue with the existing
+                // buffer.
+                Err(_) => ptr,
+                Ok(ptr) => {
+                    cap = len;
+                    ptr.as_ptr().cast()
+                }
+            };
+        }
+
+        // SAFETY: If the iterator has been advanced, the advanced elements have been copied to
+        // the beginning of the buffer and `len` has been adjusted accordingly.
+        //
+        // - `ptr` is guaranteed to point to the start of the backing buffer.
+        // - `cap` is either the original capacity or, after shrinking the buffer, equal to `len`.
+        // - `alloc` is guaranteed to be unchanged since `into_iter` has been called on the original
+        //   `Vec`.
+        unsafe { Vec::from_raw_parts(ptr, len, cap) }
+    }
+}
+
+impl<T, A> Iterator for IntoIter<T, A>
+where
+    A: Allocator,
+{
+    type Item = T;
+
+    /// # Examples
+    ///
+    /// ```
+    /// let v = kernel::kvec![1, 2, 3]?;
+    /// let mut it = v.into_iter();
+    ///
+    /// assert_eq!(it.next(), Some(1));
+    /// assert_eq!(it.next(), Some(2));
+    /// assert_eq!(it.next(), Some(3));
+    /// assert_eq!(it.next(), None);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    fn next(&mut self) -> Option<T> {
+        if self.len == 0 {
+            return None;
+        }
+
+        let current = self.ptr;
+
+        // SAFETY: We can't overflow; decreasing `self.len` by one every time we advance `self.ptr`
+        // by one guarantees that.
+        unsafe { self.ptr = self.ptr.add(1) };
+
+        self.len -= 1;
+
+        // SAFETY: `current` is guaranteed to point at a valid element within the buffer.
+        Some(unsafe { current.read() })
+    }
+
+    /// # Examples
+    ///
+    /// ```
+    /// let v: KVec<u32> = kernel::kvec![1, 2, 3]?;
+    /// let mut iter = v.into_iter();
+    /// let size = iter.size_hint().0;
+    ///
+    /// iter.next();
+    /// assert_eq!(iter.size_hint().0, size - 1);
+    ///
+    /// iter.next();
+    /// assert_eq!(iter.size_hint().0, size - 2);
+    ///
+    /// iter.next();
+    /// assert_eq!(iter.size_hint().0, size - 3);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len, Some(self.len))
+    }
+}
+
+impl<T, A> Drop for IntoIter<T, A>
+where
+    A: Allocator,
+{
+    fn drop(&mut self) {
+        // SAFETY: `self.ptr` is guaranteed to be valid by the type invariant.
+        unsafe { ptr::drop_in_place(ptr::slice_from_raw_parts_mut(self.ptr, self.len)) };
+
+        // SAFETY:
+        // - `self.buf` was previously allocated with `A`.
+        // - `self.layout` matches the `ArrayLayout` of the preceding allocation.
+        unsafe { A::free(self.buf.cast(), self.layout.into()) };
+    }
+}
+
+impl<T, A> IntoIterator for Vec<T, A>
+where
+    A: Allocator,
+{
+    type Item = T;
+    type IntoIter = IntoIter<T, A>;
+
+    /// Consumes the `Vec<T, A>` and creates an `Iterator`, which moves each value out of the
+    /// vector (from start to end).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let v = kernel::kvec![1, 2]?;
+    /// let mut v_iter = v.into_iter();
+    ///
+    /// let first_element: Option<u32> = v_iter.next();
+    ///
+    /// assert_eq!(first_element, Some(1));
+    /// assert_eq!(v_iter.next(), Some(2));
+    /// assert_eq!(v_iter.next(), None);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    ///
+    /// ```
+    /// let v = kernel::kvec![];
+    /// let mut v_iter = v.into_iter();
+    ///
+    /// let first_element: Option<u32> = v_iter.next();
+    ///
+    /// assert_eq!(first_element, None);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    #[inline]
+    fn into_iter(self) -> Self::IntoIter {
+        let buf = self.ptr;
+        let layout = self.layout;
+        let (ptr, len, _) = self.into_raw_parts();
+
+        IntoIter {
+            ptr,
+            buf,
+            len,
+            layout,
+            _p: PhantomData::<A>,
+        }
+    }
+}

rust/kernel/alloc/layout.rs

@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Memory layout.
+//!
+//! Custom layout types extending or improving [`Layout`].
+
+use core::{alloc::Layout, marker::PhantomData};
+
+/// Error when constructing an [`ArrayLayout`].
+pub struct LayoutError;
+
+/// A layout for an array `[T; n]`.
+///
+/// # Invariants
+///
+/// - `len * size_of::<T>() <= isize::MAX`.
+pub struct ArrayLayout<T> {
+    len: usize,
+    _phantom: PhantomData<fn() -> T>,
+}
+
+impl<T> Clone for ArrayLayout<T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+impl<T> Copy for ArrayLayout<T> {}
+
+const ISIZE_MAX: usize = isize::MAX as usize;
+
+impl<T> ArrayLayout<T> {
+    /// Creates a new layout for `[T; 0]`.
+    pub const fn empty() -> Self {
+        // INVARIANT: `0 * size_of::<T>() <= isize::MAX`.
+        Self {
+            len: 0,
+            _phantom: PhantomData,
+        }
+    }
+
+    /// Creates a new layout for `[T; len]`.
+    ///
+    /// # Errors
+    ///
+    /// When `len * size_of::<T>()` overflows or when `len * size_of::<T>() > isize::MAX`.
+    pub const fn new(len: usize) -> Result<Self, LayoutError> {
+        match len.checked_mul(core::mem::size_of::<T>()) {
+            Some(len) if len <= ISIZE_MAX => {
+                // INVARIANT: We checked above that `len * size_of::<T>() <= isize::MAX`.
+                Ok(Self {
+                    len,
+                    _phantom: PhantomData,
+                })
+            }
+            _ => Err(LayoutError),
+        }
+    }
+
+    /// Creates a new layout for `[T; len]`.
+    ///
+    /// # Safety
+    ///
+    /// `len` must be a value, for which `len * size_of::<T>() <= isize::MAX` is true.
+    pub unsafe fn new_unchecked(len: usize) -> Self {
+        // INVARIANT: By the safety requirements of this function
+        // `len * size_of::<T>() <= isize::MAX`.
+        Self {
+            len,
+            _phantom: PhantomData,
+        }
+    }
+
+    /// Returns the number of array elements represented by this layout.
+    pub const fn len(&self) -> usize {
+        self.len
+    }
+
+    /// Returns `true` when no array elements are represented by this layout.
+    pub const fn is_empty(&self) -> bool {
+        self.len == 0
+    }
+}
+
+impl<T> From<ArrayLayout<T>> for Layout {
+    fn from(value: ArrayLayout<T>) -> Self {
+        let res = Layout::array::<T>(value.len);
+        // SAFETY: By the type invariant of `ArrayLayout` we have
+        // `len * size_of::<T>() <= isize::MAX` and thus the result must be `Ok`.
+        unsafe { res.unwrap_unchecked() }
+    }
+}

rust/kernel/alloc/vec_ext.rs

@@ -1,185 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-//! Extensions to [`Vec`] for fallible allocations.
-
-use super::{AllocError, Flags};
-use alloc::vec::Vec;
-
-/// Extensions to [`Vec`].
-pub trait VecExt<T>: Sized {
-    /// Creates a new [`Vec`] instance with at least the given capacity.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let v = Vec::<u32>::with_capacity(20, GFP_KERNEL)?;
-    ///
-    /// assert!(v.capacity() >= 20);
-    /// # Ok::<(), Error>(())
-    /// ```
-    fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError>;
-
-    /// Appends an element to the back of the [`Vec`] instance.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = Vec::new();
-    /// v.push(1, GFP_KERNEL)?;
-    /// assert_eq!(&v, &[1]);
-    ///
-    /// v.push(2, GFP_KERNEL)?;
-    /// assert_eq!(&v, &[1, 2]);
-    /// # Ok::<(), Error>(())
-    /// ```
-    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError>;
-
-    /// Pushes clones of the elements of slice into the [`Vec`] instance.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = Vec::new();
-    /// v.push(1, GFP_KERNEL)?;
-    ///
-    /// v.extend_from_slice(&[20, 30, 40], GFP_KERNEL)?;
-    /// assert_eq!(&v, &[1, 20, 30, 40]);
-    ///
-    /// v.extend_from_slice(&[50, 60], GFP_KERNEL)?;
-    /// assert_eq!(&v, &[1, 20, 30, 40, 50, 60]);
-    /// # Ok::<(), Error>(())
-    /// ```
-    fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>
-    where
-        T: Clone;
-
-    /// Ensures that the capacity exceeds the length by at least `additional` elements.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = Vec::new();
-    /// v.push(1, GFP_KERNEL)?;
-    ///
-    /// v.reserve(10, GFP_KERNEL)?;
-    /// let cap = v.capacity();
-    /// assert!(cap >= 10);
-    ///
-    /// v.reserve(10, GFP_KERNEL)?;
-    /// let new_cap = v.capacity();
-    /// assert_eq!(new_cap, cap);
-    ///
-    /// # Ok::<(), Error>(())
-    /// ```
-    fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError>;
-}
-
-impl<T> VecExt<T> for Vec<T> {
-    fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError> {
-        let mut v = Vec::new();
-        <Self as VecExt<_>>::reserve(&mut v, capacity, flags)?;
-        Ok(v)
-    }
-
-    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> {
-        <Self as VecExt<_>>::reserve(self, 1, flags)?;
-        let s = self.spare_capacity_mut();
-        s[0].write(v);
-
-        // SAFETY: We just initialised the first spare entry, so it is safe to increase the length
-        // by 1. We also know that the new length is <= capacity because of the previous call to
-        // `reserve` above.
-        unsafe { self.set_len(self.len() + 1) };
-        Ok(())
-    }
-
-    fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>
-    where
-        T: Clone,
-    {
-        <Self as VecExt<_>>::reserve(self, other.len(), flags)?;
-        for (slot, item) in core::iter::zip(self.spare_capacity_mut(), other) {
-            slot.write(item.clone());
-        }
-
-        // SAFETY: We just initialised the `other.len()` spare entries, so it is safe to increase
-        // the length by the same amount. We also know that the new length is <= capacity because
-        // of the previous call to `reserve` above.
-        unsafe { self.set_len(self.len() + other.len()) };
-        Ok(())
-    }
-
-    #[cfg(any(test, testlib))]
-    fn reserve(&mut self, additional: usize, _flags: Flags) -> Result<(), AllocError> {
-        Vec::reserve(self, additional);
-        Ok(())
-    }
-
-    #[cfg(not(any(test, testlib)))]
-    fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError> {
-        let len = self.len();
-        let cap = self.capacity();
-
-        if cap - len >= additional {
-            return Ok(());
-        }
-
-        if core::mem::size_of::<T>() == 0 {
-            // The capacity is already `usize::MAX` for SZTs, we can't go higher.
-            return Err(AllocError);
-        }
-
-        // We know cap is <= `isize::MAX` because `Layout::array` fails if the resulting byte size
-        // is greater than `isize::MAX`. So the multiplication by two won't overflow.
-        let new_cap = core::cmp::max(cap * 2, len.checked_add(additional).ok_or(AllocError)?);
-        let layout = core::alloc::Layout::array::<T>(new_cap).map_err(|_| AllocError)?;
-
-        let (old_ptr, len, cap) = destructure(self);
-
-        // We need to make sure that `ptr` is either NULL or comes from a previous call to
-        // `krealloc_aligned`. A `Vec<T>`'s `ptr` value is not guaranteed to be NULL and might be
-        // dangling after being created with `Vec::new`. Instead, we can rely on `Vec<T>`'s capacity
-        // to be zero if no memory has been allocated yet.
-        let ptr = if cap == 0 {
-            core::ptr::null_mut()
-        } else {
-            old_ptr
-        };
-
-        // SAFETY: `ptr` is valid because it's either NULL or comes from a previous call to
-        // `krealloc_aligned`. We also verified that the type is not a ZST.
-        let new_ptr = unsafe { super::allocator::krealloc_aligned(ptr.cast(), layout, flags) };
-        if new_ptr.is_null() {
-            // SAFETY: We are just rebuilding the existing `Vec` with no changes.
-            unsafe { rebuild(self, old_ptr, len, cap) };
-            Err(AllocError)
-        } else {
-            // SAFETY: `ptr` has been reallocated with the layout for `new_cap` elements. New cap
-            // is greater than `cap`, so it continues to be >= `len`.
-            unsafe { rebuild(self, new_ptr.cast::<T>(), len, new_cap) };
-            Ok(())
-        }
-    }
-}
-
-#[cfg(not(any(test, testlib)))]
-fn destructure<T>(v: &mut Vec<T>) -> (*mut T, usize, usize) {
-    let mut tmp = Vec::new();
-    core::mem::swap(&mut tmp, v);
-    let mut tmp = core::mem::ManuallyDrop::new(tmp);
-    let len = tmp.len();
-    let cap = tmp.capacity();
-    (tmp.as_mut_ptr(), len, cap)
-}
-
-/// Rebuilds a `Vec` from a pointer, length, and capacity.
-///
-/// # Safety
-///
-/// The same as [`Vec::from_raw_parts`].
-#[cfg(not(any(test, testlib)))]
-unsafe fn rebuild<T>(v: &mut Vec<T>, ptr: *mut T, len: usize, cap: usize) {
-    // SAFETY: The safety requirements from this function satisfy those of `from_raw_parts`.
-    let mut tmp = unsafe { Vec::from_raw_parts(ptr, len, cap) };
-    core::mem::swap(&mut tmp, v);
-}

rust/kernel/error.rs

@@ -6,9 +6,10 @@
 
 use crate::{alloc::AllocError, str::CStr};
 
-use alloc::alloc::LayoutError;
+use core::alloc::LayoutError;
 
 use core::fmt;
+use core::num::NonZeroI32;
 use core::num::TryFromIntError;
 use core::str::Utf8Error;
 
@@ -20,7 +21,11 @@ pub mod code {
             $(
             #[doc = $doc]
             )*
-            pub const $err: super::Error = super::Error(-(crate::bindings::$err as i32));
+            pub const $err: super::Error =
+                match super::Error::try_from_errno(-(crate::bindings::$err as i32)) {
+                    Some(err) => err,
+                    None => panic!("Invalid errno in `declare_err!`"),
+                };
         };
     }
 
@@ -88,7 +93,7 @@ pub mod code {
 ///
 /// The value is a valid `errno` (i.e. `>= -MAX_ERRNO && < 0`).
 #[derive(Clone, Copy, PartialEq, Eq)]
-pub struct Error(core::ffi::c_int);
+pub struct Error(NonZeroI32);
 
 impl Error {
     /// Creates an [`Error`] from a kernel error code.
@@ -107,7 +112,20 @@ impl Error {
 
         // INVARIANT: The check above ensures the type invariant
         // will hold.
-        Error(errno)
+        // SAFETY: `errno` is checked above to be in a valid range.
+        unsafe { Error::from_errno_unchecked(errno) }
+    }
+
+    /// Creates an [`Error`] from a kernel error code.
+    ///
+    /// Returns [`None`] if `errno` is out-of-range.
+    const fn try_from_errno(errno: core::ffi::c_int) -> Option<Error> {
+        if errno < -(bindings::MAX_ERRNO as i32) || errno >= 0 {
+            return None;
+        }
+
+        // SAFETY: `errno` is checked above to be in a valid range.
+        Some(unsafe { Error::from_errno_unchecked(errno) })
     }
 
     /// Creates an [`Error`] from a kernel error code.
@@ -115,21 +133,22 @@ impl Error {
     /// # Safety
     ///
     /// `errno` must be within error code range (i.e. `>= -MAX_ERRNO && < 0`).
-    unsafe fn from_errno_unchecked(errno: core::ffi::c_int) -> Error {
+    const unsafe fn from_errno_unchecked(errno: core::ffi::c_int) -> Error {
         // INVARIANT: The contract ensures the type invariant
         // will hold.
-        Error(errno)
+        // SAFETY: The caller guarantees `errno` is non-zero.
+        Error(unsafe { NonZeroI32::new_unchecked(errno) })
     }
 
     /// Returns the kernel error code.
     pub fn to_errno(self) -> core::ffi::c_int {
-        self.0
+        self.0.get()
     }
 
     #[cfg(CONFIG_BLOCK)]
     pub(crate) fn to_blk_status(self) -> bindings::blk_status_t {
         // SAFETY: `self.0` is a valid error due to its invariant.
-        unsafe { bindings::errno_to_blk_status(self.0) }
+        unsafe { bindings::errno_to_blk_status(self.0.get()) }
     }
 
     /// Returns the error encoded as a pointer.
@@ -137,15 +156,15 @@ impl Error {
         #[cfg_attr(target_pointer_width = "32", allow(clippy::useless_conversion))]
         // SAFETY: `self.0` is a valid error due to its invariant.
         unsafe {
-            bindings::ERR_PTR(self.0.into()) as *mut _
+            bindings::ERR_PTR(self.0.get().into()) as *mut _
         }
     }
 
     /// Returns a string representing the error, if one exists.
-    #[cfg(not(testlib))]
+    #[cfg(not(any(test, testlib)))]
     pub fn name(&self) -> Option<&'static CStr> {
         // SAFETY: Just an FFI call, there are no extra safety requirements.
-        let ptr = unsafe { bindings::errname(-self.0) };
+        let ptr = unsafe { bindings::errname(-self.0.get()) };
         if ptr.is_null() {
             None
         } else {
@@ -159,7 +178,7 @@ impl Error {
     /// When `testlib` is configured, this always returns `None` to avoid the dependency on a
     /// kernel function so that tests that use this (e.g., by calling [`Result::unwrap`]) can still
     /// run in userspace.
-    #[cfg(testlib)]
+    #[cfg(any(test, testlib))]
     pub fn name(&self) -> Option<&'static CStr> {
         None
     }
@@ -170,9 +189,11 @@ impl fmt::Debug for Error {
         match self.name() {
             // Print out number if no name can be found.
             None => f.debug_tuple("Error").field(&-self.0).finish(),
-            // SAFETY: These strings are ASCII-only.
             Some(name) => f
-                .debug_tuple(unsafe { core::str::from_utf8_unchecked(name) })
+                .debug_tuple(
+                    // SAFETY: These strings are ASCII-only.
+                    unsafe { core::str::from_utf8_unchecked(name) },
+                )
                 .finish(),
         }
     }
@@ -274,6 +295,8 @@ pub fn from_err_ptr<T>(ptr: *mut T) -> Result<*mut T> {
     if unsafe { bindings::IS_ERR(const_ptr) } {
         // SAFETY: The FFI function does not deref the pointer.
         let err = unsafe { bindings::PTR_ERR(const_ptr) };
+
+        #[allow(clippy::unnecessary_cast)]
         // CAST: If `IS_ERR()` returns `true`,
         // then `PTR_ERR()` is guaranteed to return a
         // negative value greater-or-equal to `-bindings::MAX_ERRNO`,
@@ -283,7 +306,6 @@ pub fn from_err_ptr<T>(ptr: *mut T) -> Result<*mut T> {
         //
         // SAFETY: `IS_ERR()` ensures `err` is a
         // negative value greater-or-equal to `-bindings::MAX_ERRNO`.
-        #[allow(clippy::unnecessary_cast)]
         return Err(unsafe { Error::from_errno_unchecked(err as core::ffi::c_int) });
     }
     Ok(ptr)

rust/kernel/init.rs

@@ -13,7 +13,7 @@
 //! To initialize a `struct` with an in-place constructor you will need two things:
 //! - an in-place constructor,
 //! - a memory location that can hold your `struct` (this can be the [stack], an [`Arc<T>`],
-//!   [`UniqueArc<T>`], [`Box<T>`] or any other smart pointer that implements [`InPlaceInit`]).
+//!   [`UniqueArc<T>`], [`KBox<T>`] or any other smart pointer that implements [`InPlaceInit`]).
 //!
 //! To get an in-place constructor there are generally three options:
 //! - directly creating an in-place constructor using the [`pin_init!`] macro,
@@ -35,7 +35,7 @@
 //! that you need to write `<-` instead of `:` for fields that you want to initialize in-place.
 //!
 //! ```rust
-//! # #![allow(clippy::disallowed_names)]
+//! # #![expect(clippy::disallowed_names)]
 //! use kernel::sync::{new_mutex, Mutex};
 //! # use core::pin::Pin;
 //! #[pin_data]
@@ -55,7 +55,7 @@
 //! (or just the stack) to actually initialize a `Foo`:
 //!
 //! ```rust
-//! # #![allow(clippy::disallowed_names)]
+//! # #![expect(clippy::disallowed_names)]
 //! # use kernel::sync::{new_mutex, Mutex};
 //! # use core::pin::Pin;
 //! # #[pin_data]
@@ -68,7 +68,7 @@
 //! #     a <- new_mutex!(42, "Foo::a"),
 //! #     b: 24,
 //! # });
-//! let foo: Result<Pin<Box<Foo>>> = Box::pin_init(foo, GFP_KERNEL);
+//! let foo: Result<Pin<KBox<Foo>>> = KBox::pin_init(foo, GFP_KERNEL);
 //! ```
 //!
 //! For more information see the [`pin_init!`] macro.
@@ -87,20 +87,19 @@
 //! To declare an init macro/function you just return an [`impl PinInit<T, E>`]:
 //!
 //! ```rust
-//! # #![allow(clippy::disallowed_names)]
 //! # use kernel::{sync::Mutex, new_mutex, init::PinInit, try_pin_init};
 //! #[pin_data]
 //! struct DriverData {
 //!     #[pin]
 //!     status: Mutex<i32>,
-//!     buffer: Box<[u8; 1_000_000]>,
+//!     buffer: KBox<[u8; 1_000_000]>,
 //! }
 //!
 //! impl DriverData {
 //!     fn new() -> impl PinInit<Self, Error> {
 //!         try_pin_init!(Self {
 //!             status <- new_mutex!(0, "DriverData::status"),
-//!             buffer: Box::init(kernel::init::zeroed(), GFP_KERNEL)?,
+//!             buffer: KBox::init(kernel::init::zeroed(), GFP_KERNEL)?,
 //!         })
 //!     }
 //! }
@@ -121,11 +120,12 @@
 //!   `slot` gets called.
 //!
 //! ```rust
-//! # #![allow(unreachable_pub, clippy::disallowed_names)]
+//! # #![expect(unreachable_pub, clippy::disallowed_names)]
 //! use kernel::{init, types::Opaque};
 //! use core::{ptr::addr_of_mut, marker::PhantomPinned, pin::Pin};
 //! # mod bindings {
-//! #     #![allow(non_camel_case_types)]
+//! #     #![expect(non_camel_case_types)]
+//! #     #![expect(clippy::missing_safety_doc)]
 //! #     pub struct foo;
 //! #     pub unsafe fn init_foo(_ptr: *mut foo) {}
 //! #     pub unsafe fn destroy_foo(_ptr: *mut foo) {}
@@ -211,13 +211,12 @@
 //! [`pin_init!`]: crate::pin_init!
 
 use crate::{
-    alloc::{box_ext::BoxExt, AllocError, Flags},
+    alloc::{AllocError, Flags, KBox},
     error::{self, Error},
     sync::Arc,
     sync::UniqueArc,
     types::{Opaque, ScopeGuard},
 };
-use alloc::boxed::Box;
 use core::{
     cell::UnsafeCell,
     convert::Infallible,
@@ -238,7 +237,7 @@ pub mod macros;
 /// # Examples
 ///
 /// ```rust
-/// # #![allow(clippy::disallowed_names)]
+/// # #![expect(clippy::disallowed_names)]
 /// # use kernel::{init, macros::pin_data, pin_init, stack_pin_init, init::*, sync::Mutex, new_mutex};
 /// # use core::pin::Pin;
 /// #[pin_data]
@@ -290,7 +289,7 @@ macro_rules! stack_pin_init {
 /// # Examples
 ///
 /// ```rust,ignore
-/// # #![allow(clippy::disallowed_names)]
+/// # #![expect(clippy::disallowed_names)]
 /// # use kernel::{init, pin_init, stack_try_pin_init, init::*, sync::Mutex, new_mutex};
 /// # use macros::pin_data;
 /// # use core::{alloc::AllocError, pin::Pin};
@@ -298,7 +297,7 @@ macro_rules! stack_pin_init {
 /// struct Foo {
 ///     #[pin]
 ///     a: Mutex<usize>,
-///     b: Box<Bar>,
+///     b: KBox<Bar>,
 /// }
 ///
 /// struct Bar {
@@ -307,7 +306,7 @@ macro_rules! stack_pin_init {
 ///
 /// stack_try_pin_init!(let foo: Result<Pin<&mut Foo>, AllocError> = pin_init!(Foo {
 ///     a <- new_mutex!(42),
-///     b: Box::new(Bar {
+///     b: KBox::new(Bar {
 ///         x: 64,
 ///     }, GFP_KERNEL)?,
 /// }));
@@ -316,7 +315,7 @@ macro_rules! stack_pin_init {
 /// ```
 ///
 /// ```rust,ignore
-/// # #![allow(clippy::disallowed_names)]
+/// # #![expect(clippy::disallowed_names)]
 /// # use kernel::{init, pin_init, stack_try_pin_init, init::*, sync::Mutex, new_mutex};
 /// # use macros::pin_data;
 /// # use core::{alloc::AllocError, pin::Pin};
@@ -324,7 +323,7 @@ macro_rules! stack_pin_init {
 /// struct Foo {
 ///     #[pin]
 ///     a: Mutex<usize>,
-///     b: Box<Bar>,
+///     b: KBox<Bar>,
 /// }
 ///
 /// struct Bar {
@@ -333,7 +332,7 @@ macro_rules! stack_pin_init {
 ///
 /// stack_try_pin_init!(let foo: Pin<&mut Foo> =? pin_init!(Foo {
 ///     a <- new_mutex!(42),
-///     b: Box::new(Bar {
+///     b: KBox::new(Bar {
 ///         x: 64,
 ///     }, GFP_KERNEL)?,
 /// }));
@@ -368,7 +367,6 @@ macro_rules! stack_try_pin_init {
 /// The syntax is almost identical to that of a normal `struct` initializer:
 ///
 /// ```rust
-/// # #![allow(clippy::disallowed_names)]
 /// # use kernel::{init, pin_init, macros::pin_data, init::*};
 /// # use core::pin::Pin;
 /// #[pin_data]
@@ -392,7 +390,7 @@ macro_rules! stack_try_pin_init {
 ///     },
 /// });
 /// # initializer }
-/// # Box::pin_init(demo(), GFP_KERNEL).unwrap();
+/// # KBox::pin_init(demo(), GFP_KERNEL).unwrap();
 /// ```
 ///
 /// Arbitrary Rust expressions can be used to set the value of a variable.
@@ -413,7 +411,6 @@ macro_rules! stack_try_pin_init {
 /// To create an initializer function, simply declare it like this:
 ///
 /// ```rust
-/// # #![allow(clippy::disallowed_names)]
 /// # use kernel::{init, pin_init, init::*};
 /// # use core::pin::Pin;
 /// # #[pin_data]
@@ -440,7 +437,7 @@ macro_rules! stack_try_pin_init {
 /// Users of `Foo` can now create it like this:
 ///
 /// ```rust
-/// # #![allow(clippy::disallowed_names)]
+/// # #![expect(clippy::disallowed_names)]
 /// # use kernel::{init, pin_init, macros::pin_data, init::*};
 /// # use core::pin::Pin;
 /// # #[pin_data]
@@ -462,13 +459,12 @@ macro_rules! stack_try_pin_init {
 /// #         })
 /// #     }
 /// # }
-/// let foo = Box::pin_init(Foo::new(), GFP_KERNEL);
+/// let foo = KBox::pin_init(Foo::new(), GFP_KERNEL);
 /// ```
 ///
 /// They can also easily embed it into their own `struct`s:
 ///
 /// ```rust
-/// # #![allow(clippy::disallowed_names)]
 /// # use kernel::{init, pin_init, macros::pin_data, init::*};
 /// # use core::pin::Pin;
 /// # #[pin_data]
@@ -541,6 +537,7 @@ macro_rules! stack_try_pin_init {
 /// }
 /// pin_init!(&this in Buf {
 ///     buf: [0; 64],
+///     // SAFETY: TODO.
 ///     ptr: unsafe { addr_of_mut!((*this.as_ptr()).buf).cast() },
 ///     pin: PhantomPinned,
 /// });
@@ -590,11 +587,10 @@ macro_rules! pin_init {
 /// # Examples
 ///
 /// ```rust
-/// # #![feature(new_uninit)]
 /// use kernel::{init::{self, PinInit}, error::Error};
 /// #[pin_data]
 /// struct BigBuf {
-///     big: Box<[u8; 1024 * 1024 * 1024]>,
+///     big: KBox<[u8; 1024 * 1024 * 1024]>,
 ///     small: [u8; 1024 * 1024],
 ///     ptr: *mut u8,
 /// }
@@ -602,7 +598,7 @@ macro_rules! pin_init {
 /// impl BigBuf {
 ///     fn new() -> impl PinInit<Self, Error> {
 ///         try_pin_init!(Self {
-///             big: Box::init(init::zeroed(), GFP_KERNEL)?,
+///             big: KBox::init(init::zeroed(), GFP_KERNEL)?,
 ///             small: [0; 1024 * 1024],
 ///             ptr: core::ptr::null_mut(),
 ///         }? Error)
@@ -694,16 +690,16 @@ macro_rules! init {
 /// # Examples
 ///
 /// ```rust
-/// use kernel::{init::{PinInit, zeroed}, error::Error};
+/// use kernel::{alloc::KBox, init::{PinInit, zeroed}, error::Error};
 /// struct BigBuf {
-///     big: Box<[u8; 1024 * 1024 * 1024]>,
+///     big: KBox<[u8; 1024 * 1024 * 1024]>,
 ///     small: [u8; 1024 * 1024],
 /// }
 ///
 /// impl BigBuf {
 ///     fn new() -> impl Init<Self, Error> {
 ///         try_init!(Self {
-///             big: Box::init(zeroed(), GFP_KERNEL)?,
+///             big: KBox::init(zeroed(), GFP_KERNEL)?,
 ///             small: [0; 1024 * 1024],
 ///         }? Error)
 ///     }
@@ -814,8 +810,8 @@ macro_rules! assert_pinned {
 /// A pin-initializer for the type `T`.
 ///
 /// To use this initializer, you will need a suitable memory location that can hold a `T`. This can
-/// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>`] or even the stack (see [`stack_pin_init!`]). Use the
-/// [`InPlaceInit::pin_init`] function of a smart pointer like [`Arc<T>`] on this.
+/// be [`KBox<T>`], [`Arc<T>`], [`UniqueArc<T>`] or even the stack (see [`stack_pin_init!`]). Use
+/// the [`InPlaceInit::pin_init`] function of a smart pointer like [`Arc<T>`] on this.
 ///
 /// Also see the [module description](self).
 ///
@@ -854,7 +850,7 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
     /// # Examples
     ///
     /// ```rust
-    /// # #![allow(clippy::disallowed_names)]
+    /// # #![expect(clippy::disallowed_names)]
     /// use kernel::{types::Opaque, init::pin_init_from_closure};
     /// #[repr(C)]
     /// struct RawFoo([u8; 16]);
@@ -875,6 +871,7 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
     /// }
     ///
     /// let foo = pin_init!(Foo {
+    ///     // SAFETY: TODO.
     ///     raw <- unsafe {
     ///         Opaque::ffi_init(|s| {
     ///             init_foo(s);
@@ -894,7 +891,7 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
 }
 
 /// An initializer returned by [`PinInit::pin_chain`].
-pub struct ChainPinInit<I, F, T: ?Sized, E>(I, F, __internal::Invariant<(E, Box<T>)>);
+pub struct ChainPinInit<I, F, T: ?Sized, E>(I, F, __internal::Invariant<(E, KBox<T>)>);
 
 // SAFETY: The `__pinned_init` function is implemented such that it
 // - returns `Ok(())` on successful initialization,
@@ -920,8 +917,8 @@ where
 /// An initializer for `T`.
 ///
 /// To use this initializer, you will need a suitable memory location that can hold a `T`. This can
-/// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>`] or even the stack (see [`stack_pin_init!`]). Use the
-/// [`InPlaceInit::init`] function of a smart pointer like [`Arc<T>`] on this. Because
+/// be [`KBox<T>`], [`Arc<T>`], [`UniqueArc<T>`] or even the stack (see [`stack_pin_init!`]). Use
+/// the [`InPlaceInit::init`] function of a smart pointer like [`Arc<T>`] on this. Because
 /// [`PinInit<T, E>`] is a super trait, you can use every function that takes it as well.
 ///
 /// Also see the [module description](self).
@@ -965,7 +962,7 @@ pub unsafe trait Init<T: ?Sized, E = Infallible>: PinInit<T, E> {
     /// # Examples
     ///
     /// ```rust
-    /// # #![allow(clippy::disallowed_names)]
+    /// # #![expect(clippy::disallowed_names)]
     /// use kernel::{types::Opaque, init::{self, init_from_closure}};
     /// struct Foo {
     ///     buf: [u8; 1_000_000],
@@ -993,7 +990,7 @@ pub unsafe trait Init<T: ?Sized, E = Infallible>: PinInit<T, E> {
 }
 
 /// An initializer returned by [`Init::chain`].
-pub struct ChainInit<I, F, T: ?Sized, E>(I, F, __internal::Invariant<(E, Box<T>)>);
+pub struct ChainInit<I, F, T: ?Sized, E>(I, F, __internal::Invariant<(E, KBox<T>)>);
 
 // SAFETY: The `__init` function is implemented such that it
 // - returns `Ok(())` on successful initialization,
@@ -1077,8 +1074,9 @@ pub fn uninit<T, E>() -> impl Init<MaybeUninit<T>, E> {
 /// # Examples
 ///
 /// ```rust
-/// use kernel::{error::Error, init::init_array_from_fn};
-/// let array: Box<[usize; 1_000]> = Box::init::<Error>(init_array_from_fn(|i| i), GFP_KERNEL).unwrap();
+/// use kernel::{alloc::KBox, error::Error, init::init_array_from_fn};
+/// let array: KBox<[usize; 1_000]> =
+///     KBox::init::<Error>(init_array_from_fn(|i| i), GFP_KERNEL).unwrap();
 /// assert_eq!(array.len(), 1_000);
 /// ```
 pub fn init_array_from_fn<I, const N: usize, T, E>(
@@ -1162,6 +1160,7 @@ where
 // SAFETY: Every type can be initialized by-value.
 unsafe impl<T, E> Init<T, E> for T {
     unsafe fn __init(self, slot: *mut T) -> Result<(), E> {
+        // SAFETY: TODO.
         unsafe { slot.write(self) };
         Ok(())
     }
@@ -1170,6 +1169,7 @@ unsafe impl<T, E> Init<T, E> for T {
 // SAFETY: Every type can be initialized by-value. `__pinned_init` calls `__init`.
 unsafe impl<T, E> PinInit<T, E> for T {
     unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
+        // SAFETY: TODO.
         unsafe { self.__init(slot) }
     }
 }
@@ -1243,26 +1243,6 @@ impl<T> InPlaceInit<T> for Arc<T> {
     }
 }
 
-impl<T> InPlaceInit<T> for Box<T> {
-    type PinnedSelf = Pin<Self>;
-
-    #[inline]
-    fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Self::PinnedSelf, E>
-    where
-        E: From<AllocError>,
-    {
-        <Box<_> as BoxExt<_>>::new_uninit(flags)?.write_pin_init(init)
-    }
-
-    #[inline]
-    fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
-    where
-        E: From<AllocError>,
-    {
-        <Box<_> as BoxExt<_>>::new_uninit(flags)?.write_init(init)
-    }
-}
-
 impl<T> InPlaceInit<T> for UniqueArc<T> {
     type PinnedSelf = Pin<Self>;
 
@@ -1299,28 +1279,6 @@ pub trait InPlaceWrite<T> {
     fn write_pin_init<E>(self, init: impl PinInit<T, E>) -> Result<Pin<Self::Initialized>, E>;
 }
 
-impl<T> InPlaceWrite<T> for Box<MaybeUninit<T>> {
-    type Initialized = Box<T>;
-
-    fn write_init<E>(mut self, init: impl Init<T, E>) -> Result<Self::Initialized, E> {
-        let slot = self.as_mut_ptr();
-        // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
-        // slot is valid.
-        unsafe { init.__init(slot)? };
-        // SAFETY: All fields have been initialized.
-        Ok(unsafe { self.assume_init() })
-    }
-
-    fn write_pin_init<E>(mut self, init: impl PinInit<T, E>) -> Result<Pin<Self::Initialized>, E> {
-        let slot = self.as_mut_ptr();
-        // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
-        // slot is valid and will not be moved, because we pin it later.
-        unsafe { init.__pinned_init(slot)? };
-        // SAFETY: All fields have been initialized.
-        Ok(unsafe { self.assume_init() }.into())
-    }
-}
-
 impl<T> InPlaceWrite<T> for UniqueArc<MaybeUninit<T>> {
     type Initialized = UniqueArc<T>;
 
@@ -1411,6 +1369,7 @@ pub fn zeroed<T: Zeroable>() -> impl Init<T> {
 
 macro_rules! impl_zeroable {
     ($($({$($generics:tt)*})? $t:ty, )*) => {
+        // SAFETY: Safety comments written in the macro invocation.
         $(unsafe impl$($($generics)*)? Zeroable for $t {})*
     };
 }
@@ -1451,7 +1410,7 @@ impl_zeroable! {
     //
     // In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant.
     {<T: ?Sized>} Option<NonNull<T>>,
-    {<T: ?Sized>} Option<Box<T>>,
+    {<T: ?Sized>} Option<KBox<T>>,
 
     // SAFETY: `null` pointer is valid.
     //

rust/kernel/init/__internal.rs

@@ -15,9 +15,10 @@ use super::*;
 /// [this table]: https://doc.rust-lang.org/nomicon/phantom-data.html#table-of-phantomdata-patterns
 pub(super) type Invariant<T> = PhantomData<fn(*mut T) -> *mut T>;
 
-/// This is the module-internal type implementing `PinInit` and `Init`. It is unsafe to create this
-/// type, since the closure needs to fulfill the same safety requirement as the
-/// `__pinned_init`/`__init` functions.
+/// Module-internal type implementing `PinInit` and `Init`.
+///
+/// It is unsafe to create this type, since the closure needs to fulfill the same safety
+/// requirement as the `__pinned_init`/`__init` functions.
 pub(crate) struct InitClosure<F, T: ?Sized, E>(pub(crate) F, pub(crate) Invariant<(E, T)>);
 
 // SAFETY: While constructing the `InitClosure`, the user promised that it upholds the
@@ -53,6 +54,7 @@ where
 pub unsafe trait HasPinData {
     type PinData: PinData;
 
+    #[expect(clippy::missing_safety_doc)]
     unsafe fn __pin_data() -> Self::PinData;
 }
 
@@ -82,6 +84,7 @@ pub unsafe trait PinData: Copy {
 pub unsafe trait HasInitData {
     type InitData: InitData;
 
+    #[expect(clippy::missing_safety_doc)]
     unsafe fn __init_data() -> Self::InitData;
 }
 
@@ -102,7 +105,7 @@ pub unsafe trait InitData: Copy {
     }
 }
 
-pub struct AllData<T: ?Sized>(PhantomData<fn(Box<T>) -> Box<T>>);
+pub struct AllData<T: ?Sized>(PhantomData<fn(KBox<T>) -> KBox<T>>);
 
 impl<T: ?Sized> Clone for AllData<T> {
     fn clone(&self) -> Self {
@@ -112,10 +115,12 @@ impl<T: ?Sized> Clone for AllData<T> {
 
 impl<T: ?Sized> Copy for AllData<T> {}
 
+// SAFETY: TODO.
 unsafe impl<T: ?Sized> InitData for AllData<T> {
     type Datee = T;
 }
 
+// SAFETY: TODO.
 unsafe impl<T: ?Sized> HasInitData for T {
     type InitData = AllData<T>;
 

rust/kernel/init/macros.rs

@@ -182,13 +182,13 @@
 //!     // Normally `Drop` bounds do not have the correct semantics, but for this purpose they do
 //!     // (normally people want to know if a type has any kind of drop glue at all, here we want
 //!     // to know if it has any kind of custom drop glue, which is exactly what this bound does).
-//!     #[allow(drop_bounds)]
+//!     #[expect(drop_bounds)]
 //!     impl<T: ::core::ops::Drop> MustNotImplDrop for T {}
 //!     impl<T> MustNotImplDrop for Bar<T> {}
 //!     // Here comes a convenience check, if one implemented `PinnedDrop`, but forgot to add it to
 //!     // `#[pin_data]`, then this will error with the same mechanic as above, this is not needed
 //!     // for safety, but a good sanity check, since no normal code calls `PinnedDrop::drop`.
-//!     #[allow(non_camel_case_types)]
+//!     #[expect(non_camel_case_types)]
 //!     trait UselessPinnedDropImpl_you_need_to_specify_PinnedDrop {}
 //!     impl<
 //!         T: ::kernel::init::PinnedDrop,
@@ -513,6 +513,7 @@ macro_rules! __pinned_drop {
             }
         ),
     ) => {
+        // SAFETY: TODO.
         unsafe $($impl_sig)* {
             // Inherit all attributes and the type/ident tokens for the signature.
             $(#[$($attr)*])*
@@ -872,6 +873,7 @@ macro_rules! __pin_data {
                 }
             }
 
+            // SAFETY: TODO.
             unsafe impl<$($impl_generics)*>
                 $crate::init::__internal::PinData for __ThePinData<$($ty_generics)*>
             where $($whr)*
@@ -923,14 +925,14 @@ macro_rules! __pin_data {
         // `Drop`. Additionally we will implement this trait for the struct leading to a conflict,
         // if it also implements `Drop`
         trait MustNotImplDrop {}
-        #[allow(drop_bounds)]
+        #[expect(drop_bounds)]
         impl<T: ::core::ops::Drop> MustNotImplDrop for T {}
         impl<$($impl_generics)*> MustNotImplDrop for $name<$($ty_generics)*>
         where $($whr)* {}
         // We also take care to prevent users from writing a useless `PinnedDrop` implementation.
         // They might implement `PinnedDrop` correctly for the struct, but forget to give
         // `PinnedDrop` as the parameter to `#[pin_data]`.
-        #[allow(non_camel_case_types)]
+        #[expect(non_camel_case_types)]
         trait UselessPinnedDropImpl_you_need_to_specify_PinnedDrop {}
         impl<T: $crate::init::PinnedDrop>
             UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for T {}
@@ -987,6 +989,7 @@ macro_rules! __pin_data {
         //
         // The functions are `unsafe` to prevent accidentally calling them.
         #[allow(dead_code)]
+        #[expect(clippy::missing_safety_doc)]
         impl<$($impl_generics)*> $pin_data<$($ty_generics)*>
         where $($whr)*
         {
@@ -997,6 +1000,7 @@ macro_rules! __pin_data {
                     slot: *mut $p_type,
                     init: impl $crate::init::PinInit<$p_type, E>,
                 ) -> ::core::result::Result<(), E> {
+                    // SAFETY: TODO.
                     unsafe { $crate::init::PinInit::__pinned_init(init, slot) }
                 }
             )*
@@ -1007,6 +1011,7 @@ macro_rules! __pin_data {
                     slot: *mut $type,
                     init: impl $crate::init::Init<$type, E>,
                 ) -> ::core::result::Result<(), E> {
+                    // SAFETY: TODO.
                     unsafe { $crate::init::Init::__init(init, slot) }
                 }
             )*
@@ -1121,6 +1126,8 @@ macro_rules! __init_internal {
         // no possibility of returning without `unsafe`.
         struct __InitOk;
         // Get the data about fields from the supplied type.
+        //
+        // SAFETY: TODO.
         let data = unsafe {
             use $crate::init::__internal::$has_data;
             // Here we abuse `paste!` to retokenize `$t`. Declarative macros have some internal
@@ -1176,6 +1183,7 @@ macro_rules! __init_internal {
         let init = move |slot| -> ::core::result::Result<(), $err> {
             init(slot).map(|__InitOk| ())
         };
+        // SAFETY: TODO.
         let init = unsafe { $crate::init::$construct_closure::<_, $err>(init) };
         init
     }};
@@ -1324,6 +1332,8 @@ macro_rules! __init_internal {
         // Endpoint, nothing more to munch, create the initializer.
         // Since we are in the closure that is never called, this will never get executed.
         // We abuse `slot` to get the correct type inference here:
+        //
+        // SAFETY: TODO.
         unsafe {
             // Here we abuse `paste!` to retokenize `$t`. Declarative macros have some internal
             // information that is associated to already parsed fragments, so a path fragment

rust/kernel/ioctl.rs

@@ -4,7 +4,7 @@
 //!
 //! C header: [`include/asm-generic/ioctl.h`](srctree/include/asm-generic/ioctl.h)
 
-#![allow(non_snake_case)]
+#![expect(non_snake_case)]
 
 use crate::build_assert;
 

rust/kernel/lib.rs

@@ -15,7 +15,8 @@
 #![feature(arbitrary_self_types)]
 #![feature(coerce_unsized)]
 #![feature(dispatch_from_dyn)]
-#![feature(new_uninit)]
+#![feature(inline_const)]
+#![feature(lint_reasons)]
 #![feature(unsize)]
 
 // Ensure conditional compilation based on the kernel configuration works;

rust/kernel/list.rs

@@ -348,6 +348,7 @@ impl<T: ?Sized + ListItem<ID>, const ID: u64> List<T, ID> {
     ///
     /// `item` must not be in a different linked list (with the same id).
     pub unsafe fn remove(&mut self, item: &T) -> Option<ListArc<T, ID>> {
+        // SAFETY: TODO.
         let mut item = unsafe { ListLinks::fields(T::view_links(item)) };
         // SAFETY: The user provided a reference, and reference are never dangling.
         //

rust/kernel/list/arc_field.rs

@@ -56,7 +56,7 @@ impl<T, const ID: u64> ListArcField<T, ID> {
     ///
     /// The caller must have mutable access to the `ListArc<ID>` containing the struct with this
     /// field for the duration of the returned reference.
-    #[allow(clippy::mut_from_ref)]
+    #[expect(clippy::mut_from_ref)]
     pub unsafe fn assert_mut(&self) -> &mut T {
         // SAFETY: The caller has exclusive access to the `ListArc`, so they also have exclusive
         // access to this field.

rust/kernel/prelude.rs

@@ -14,10 +14,7 @@
 #[doc(no_inline)]
 pub use core::pin::Pin;
 
-pub use crate::alloc::{box_ext::BoxExt, flags::*, vec_ext::VecExt};
-
-#[doc(no_inline)]
-pub use alloc::{boxed::Box, vec::Vec};
+pub use crate::alloc::{flags::*, Box, KBox, KVBox, KVVec, KVec, VBox, VVec, Vec};
 
 #[doc(no_inline)]
 pub use macros::{module, pin_data, pinned_drop, vtable, Zeroable};

rust/kernel/print.rs

@@ -14,6 +14,7 @@ use core::{
 use crate::str::RawFormatter;
 
 // Called from `vsprintf` with format specifier `%pA`.
+#[expect(clippy::missing_safety_doc)]
 #[no_mangle]
 unsafe extern "C" fn rust_fmt_argument(
     buf: *mut c_char,
@@ -23,6 +24,7 @@ unsafe extern "C" fn rust_fmt_argument(
     use fmt::Write;
     // SAFETY: The C contract guarantees that `buf` is valid if it's less than `end`.
     let mut w = unsafe { RawFormatter::from_ptrs(buf.cast(), end.cast()) };
+    // SAFETY: TODO.
     let _ = w.write_fmt(unsafe { *(ptr as *const fmt::Arguments<'_>) });
     w.pos().cast()
 }
@@ -102,6 +104,7 @@ pub unsafe fn call_printk(
 ) {
     // `_printk` does not seem to fail in any path.
     #[cfg(CONFIG_PRINTK)]
+    // SAFETY: TODO.
     unsafe {
         bindings::_printk(
             format_string.as_ptr() as _,
@@ -137,7 +140,7 @@ pub fn call_printk_cont(args: fmt::Arguments<'_>) {
 #[doc(hidden)]
 #[cfg(not(testlib))]
 #[macro_export]
-#[allow(clippy::crate_in_macro_def)]
+#[expect(clippy::crate_in_macro_def)]
 macro_rules! print_macro (
     // The non-continuation cases (most of them, e.g. `INFO`).
     ($format_string:path, false, $($arg:tt)+) => (

rust/kernel/rbtree.rs

@@ -7,7 +7,6 @@
 //! Reference: <https://docs.kernel.org/core-api/rbtree.html>
 
 use crate::{alloc::Flags, bindings, container_of, error::Result, prelude::*};
-use alloc::boxed::Box;
 use core::{
     cmp::{Ord, Ordering},
     marker::PhantomData,
@@ -497,7 +496,7 @@ impl<K, V> Drop for RBTree<K, V> {
             // but it is not observable. The loop invariant is still maintained.
 
             // SAFETY: `this` is valid per the loop invariant.
-            unsafe { drop(Box::from_raw(this.cast_mut())) };
+            unsafe { drop(KBox::from_raw(this.cast_mut())) };
         }
     }
 }
@@ -764,7 +763,7 @@ impl<'a, K, V> Cursor<'a, K, V> {
         // point to the links field of `Node<K, V>` objects.
         let this = unsafe { container_of!(self.current.as_ptr(), Node<K, V>, links) }.cast_mut();
         // SAFETY: `this` is valid by the type invariants as described above.
-        let node = unsafe { Box::from_raw(this) };
+        let node = unsafe { KBox::from_raw(this) };
         let node = RBTreeNode { node };
         // SAFETY: The reference to the tree used to create the cursor outlives the cursor, so
         // the tree cannot change. By the tree invariant, all nodes are valid.
@@ -809,7 +808,7 @@ impl<'a, K, V> Cursor<'a, K, V> {
             // point to the links field of `Node<K, V>` objects.
             let this = unsafe { container_of!(neighbor, Node<K, V>, links) }.cast_mut();
             // SAFETY: `this` is valid by the type invariants as described above.
-            let node = unsafe { Box::from_raw(this) };
+            let node = unsafe { KBox::from_raw(this) };
             return Some(RBTreeNode { node });
         }
         None
@@ -1038,7 +1037,7 @@ impl<K, V> Iterator for IterRaw<K, V> {
 /// It contains the memory needed to hold a node that can be inserted into a red-black tree. One
 /// can be obtained by directly allocating it ([`RBTreeNodeReservation::new`]).
 pub struct RBTreeNodeReservation<K, V> {
-    node: Box<MaybeUninit<Node<K, V>>>,
+    node: KBox<MaybeUninit<Node<K, V>>>,
 }
 
 impl<K, V> RBTreeNodeReservation<K, V> {
@@ -1046,7 +1045,7 @@ impl<K, V> RBTreeNodeReservation<K, V> {
     /// call to [`RBTree::insert`].
     pub fn new(flags: Flags) -> Result<RBTreeNodeReservation<K, V>> {
         Ok(RBTreeNodeReservation {
-            node: <Box<_> as BoxExt<_>>::new_uninit(flags)?,
+            node: KBox::new_uninit(flags)?,
         })
     }
 }
@@ -1062,14 +1061,15 @@ impl<K, V> RBTreeNodeReservation<K, V> {
     /// Initialises a node reservation.
     ///
     /// It then becomes an [`RBTreeNode`] that can be inserted into a tree.
-    pub fn into_node(mut self, key: K, value: V) -> RBTreeNode<K, V> {
-        self.node.write(Node {
-            key,
-            value,
-            links: bindings::rb_node::default(),
-        });
-        // SAFETY: We just wrote to it.
-        let node = unsafe { self.node.assume_init() };
+    pub fn into_node(self, key: K, value: V) -> RBTreeNode<K, V> {
+        let node = KBox::write(
+            self.node,
+            Node {
+                key,
+                value,
+                links: bindings::rb_node::default(),
+            },
+        );
         RBTreeNode { node }
     }
 }
@@ -1079,7 +1079,7 @@ impl<K, V> RBTreeNodeReservation<K, V> {
 /// The node is fully initialised (with key and value) and can be inserted into a tree without any
 /// extra allocations or failure paths.
 pub struct RBTreeNode<K, V> {
-    node: Box<Node<K, V>>,
+    node: KBox<Node<K, V>>,
 }
 
 impl<K, V> RBTreeNode<K, V> {
@@ -1091,7 +1091,9 @@ impl<K, V> RBTreeNode<K, V> {
 
     /// Get the key and value from inside the node.
     pub fn to_key_value(self) -> (K, V) {
-        (self.node.key, self.node.value)
+        let node = KBox::into_inner(self.node);
+
+        (node.key, node.value)
     }
 }
 
@@ -1113,7 +1115,7 @@ impl<K, V> RBTreeNode<K, V> {
     /// may be freed (but only for the key/value; memory for the node itself is kept for reuse).
     pub fn into_reservation(self) -> RBTreeNodeReservation<K, V> {
         RBTreeNodeReservation {
-            node: Box::drop_contents(self.node),
+            node: KBox::drop_contents(self.node),
         }
     }
 }
@@ -1164,7 +1166,7 @@ impl<'a, K, V> RawVacantEntry<'a, K, V> {
     /// The `node` must have a key such that inserting it here does not break the ordering of this
     /// [`RBTree`].
     fn insert(self, node: RBTreeNode<K, V>) -> &'a mut V {
-        let node = Box::into_raw(node.node);
+        let node = KBox::into_raw(node.node);
 
         // SAFETY: `node` is valid at least until we call `Box::from_raw`, which only happens when
         // the node is removed or replaced.
@@ -1238,21 +1240,24 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> {
             // SAFETY: The node was a node in the tree, but we removed it, so we can convert it
             // back into a box.
             node: unsafe {
-                Box::from_raw(container_of!(self.node_links, Node<K, V>, links).cast_mut())
+                KBox::from_raw(container_of!(self.node_links, Node<K, V>, links).cast_mut())
             },
         }
     }
 
     /// Takes the value of the entry out of the map, and returns it.
     pub fn remove(self) -> V {
-        self.remove_node().node.value
+        let rb_node = self.remove_node();
+        let node = KBox::into_inner(rb_node.node);
+
+        node.value
     }
 
     /// Swap the current node for the provided node.
     ///
     /// The key of both nodes must be equal.
     fn replace(self, node: RBTreeNode<K, V>) -> RBTreeNode<K, V> {
-        let node = Box::into_raw(node.node);
+        let node = KBox::into_raw(node.node);
 
         // SAFETY: `node` is valid at least until we call `Box::from_raw`, which only happens when
         // the node is removed or replaced.
@@ -1268,7 +1273,7 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> {
         // - `self.node_ptr` produces a valid pointer to a node in the tree.
         // - Now that we removed this entry from the tree, we can convert the node to a box.
         let old_node =
-            unsafe { Box::from_raw(container_of!(self.node_links, Node<K, V>, links).cast_mut()) };
+            unsafe { KBox::from_raw(container_of!(self.node_links, Node<K, V>, links).cast_mut()) };
 
         RBTreeNode { node: old_node }
     }

rust/kernel/std_vendor.rs

@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
+//! Rust standard library vendored code.
+//!
 //! The contents of this file come from the Rust standard library, hosted in
 //! the <https://github.com/rust-lang/rust> repository, licensed under
 //! "Apache-2.0 OR MIT" and adapted for kernel use. For copyright details,
@@ -14,7 +16,7 @@
 ///
 /// ```rust
 /// let a = 2;
-/// # #[allow(clippy::dbg_macro)]
+/// # #[expect(clippy::disallowed_macros)]
 /// let b = dbg!(a * 2) + 1;
 /// //      ^-- prints: [src/main.rs:2] a * 2 = 4
 /// assert_eq!(b, 5);
@@ -52,7 +54,7 @@
 /// With a method call:
 ///
 /// ```rust
-/// # #[allow(clippy::dbg_macro)]
+/// # #[expect(clippy::disallowed_macros)]
 /// fn foo(n: usize) {
 ///     if dbg!(n.checked_sub(4)).is_some() {
 ///         // ...
@@ -71,7 +73,7 @@
 /// Naive factorial implementation:
 ///
 /// ```rust
-/// # #[allow(clippy::dbg_macro)]
+/// # #[expect(clippy::disallowed_macros)]
 /// # {
 /// fn factorial(n: u32) -> u32 {
 ///     if dbg!(n <= 1) {
@@ -118,7 +120,7 @@
 /// a tuple (and return it, too):
 ///
 /// ```
-/// # #[allow(clippy::dbg_macro)]
+/// # #![expect(clippy::disallowed_macros)]
 /// assert_eq!(dbg!(1usize, 2u32), (1, 2));
 /// ```
 ///
@@ -127,7 +129,7 @@
 /// invocations. You can use a 1-tuple directly if you need one:
 ///
 /// ```
-/// # #[allow(clippy::dbg_macro)]
+/// # #[expect(clippy::disallowed_macros)]
 /// # {
 /// assert_eq!(1, dbg!(1u32,)); // trailing comma ignored
 /// assert_eq!((1,), dbg!((1u32,))); // 1-tuple

rust/kernel/str.rs

@@ -2,8 +2,7 @@
 
 //! String representations.
 
-use crate::alloc::{flags::*, vec_ext::VecExt, AllocError};
-use alloc::vec::Vec;
+use crate::alloc::{flags::*, AllocError, KVec};
 use core::fmt::{self, Write};
 use core::ops::{self, Deref, DerefMut, Index};
 
@@ -162,10 +161,10 @@ impl CStr {
     /// Returns the length of this string with `NUL`.
     #[inline]
     pub const fn len_with_nul(&self) -> usize {
-        // SAFETY: This is one of the invariant of `CStr`.
-        // We add a `unreachable_unchecked` here to hint the optimizer that
-        // the value returned from this function is non-zero.
         if self.0.is_empty() {
+            // SAFETY: This is one of the invariant of `CStr`.
+            // We add a `unreachable_unchecked` here to hint the optimizer that
+            // the value returned from this function is non-zero.
             unsafe { core::hint::unreachable_unchecked() };
         }
         self.0.len()
@@ -301,6 +300,7 @@ impl CStr {
     /// ```
     #[inline]
     pub unsafe fn as_str_unchecked(&self) -> &str {
+        // SAFETY: TODO.
         unsafe { core::str::from_utf8_unchecked(self.as_bytes()) }
     }
 
@@ -524,7 +524,28 @@ macro_rules! c_str {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use alloc::format;
+
+    struct String(CString);
+
+    impl String {
+        fn from_fmt(args: fmt::Arguments<'_>) -> Self {
+            String(CString::try_from_fmt(args).unwrap())
+        }
+    }
+
+    impl Deref for String {
+        type Target = str;
+
+        fn deref(&self) -> &str {
+            self.0.to_str().unwrap()
+        }
+    }
+
+    macro_rules! format {
+        ($($f:tt)*) => ({
+            &*String::from_fmt(kernel::fmt!($($f)*))
+        })
+    }
 
     const ALL_ASCII_CHARS: &'static str =
         "\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\x09\\x0a\\x0b\\x0c\\x0d\\x0e\\x0f\
@@ -790,7 +811,7 @@ impl fmt::Write for Formatter {
 /// assert_eq!(s.is_ok(), false);
 /// ```
 pub struct CString {
-    buf: Vec<u8>,
+    buf: KVec<u8>,
 }
 
 impl CString {
@@ -803,7 +824,7 @@ impl CString {
         let size = f.bytes_written();
 
         // Allocate a vector with the required number of bytes, and write to it.
-        let mut buf = <Vec<_> as VecExt<_>>::with_capacity(size, GFP_KERNEL)?;
+        let mut buf = KVec::with_capacity(size, GFP_KERNEL)?;
         // SAFETY: The buffer stored in `buf` is at least of size `size` and is valid for writes.
         let mut f = unsafe { Formatter::from_buffer(buf.as_mut_ptr(), size) };
         f.write_fmt(args)?;
@@ -850,10 +871,9 @@ impl<'a> TryFrom<&'a CStr> for CString {
     type Error = AllocError;
 
     fn try_from(cstr: &'a CStr) -> Result<CString, AllocError> {
-        let mut buf = Vec::new();
+        let mut buf = KVec::new();
 
-        <Vec<_> as VecExt<_>>::extend_from_slice(&mut buf, cstr.as_bytes_with_nul(), GFP_KERNEL)
-            .map_err(|_| AllocError)?;
+        buf.extend_from_slice(cstr.as_bytes_with_nul(), GFP_KERNEL)?;
 
         // INVARIANT: The `CStr` and `CString` types have the same invariants for
         // the string data, and we copied it over without changes.

rust/kernel/sync/arc.rs

@@ -17,13 +17,12 @@
 //! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html
 
 use crate::{
-    alloc::{box_ext::BoxExt, AllocError, Flags},
+    alloc::{AllocError, Flags, KBox},
     bindings,
     init::{self, InPlaceInit, Init, PinInit},
     try_init,
     types::{ForeignOwnable, Opaque},
 };
-use alloc::boxed::Box;
 use core::{
     alloc::Layout,
     fmt,
@@ -201,11 +200,11 @@ impl<T> Arc<T> {
             data: contents,
         };
 
-        let inner = <Box<_> as BoxExt<_>>::new(value, flags)?;
+        let inner = KBox::new(value, flags)?;
 
         // SAFETY: We just created `inner` with a reference count of 1, which is owned by the new
         // `Arc` object.
-        Ok(unsafe { Self::from_inner(Box::leak(inner).into()) })
+        Ok(unsafe { Self::from_inner(KBox::leak(inner).into()) })
     }
 }
 
@@ -338,7 +337,7 @@ impl<T: 'static> ForeignOwnable for Arc<T> {
     }
 
     unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> ArcBorrow<'a, T> {
-        // SAFETY: By the safety requirement of this function, we know that `ptr` came from
+        // By the safety requirement of this function, we know that `ptr` came from
         // a previous call to `Arc::into_foreign`.
         let inner = NonNull::new(ptr as *mut ArcInner<T>).unwrap();
 
@@ -398,8 +397,8 @@ impl<T: ?Sized> Drop for Arc<T> {
         if is_zero {
             // The count reached zero, we must free the memory.
             //
-            // SAFETY: The pointer was initialised from the result of `Box::leak`.
-            unsafe { drop(Box::from_raw(self.ptr.as_ptr())) };
+            // SAFETY: The pointer was initialised from the result of `KBox::leak`.
+            unsafe { drop(KBox::from_raw(self.ptr.as_ptr())) };
         }
     }
 }
@@ -641,7 +640,7 @@ impl<T> UniqueArc<T> {
     /// Tries to allocate a new [`UniqueArc`] instance whose contents are not initialised yet.
     pub fn new_uninit(flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
         // INVARIANT: The refcount is initialised to a non-zero value.
-        let inner = Box::try_init::<AllocError>(
+        let inner = KBox::try_init::<AllocError>(
             try_init!(ArcInner {
                 // SAFETY: There are no safety requirements for this FFI call.
                 refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }),
@@ -651,8 +650,8 @@ impl<T> UniqueArc<T> {
         )?;
         Ok(UniqueArc {
             // INVARIANT: The newly-created object has a refcount of 1.
-            // SAFETY: The pointer from the `Box` is valid.
-            inner: unsafe { Arc::from_inner(Box::leak(inner).into()) },
+            // SAFETY: The pointer from the `KBox` is valid.
+            inner: unsafe { Arc::from_inner(KBox::leak(inner).into()) },
         })
     }
 }

rust/kernel/sync/arc/std_vendor.rs

@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
+//! Rust standard library vendored code.
+//!
 //! The contents of this file come from the Rust standard library, hosted in
 //! the <https://github.com/rust-lang/rust> repository, licensed under
 //! "Apache-2.0 OR MIT" and adapted for kernel use. For copyright details,

rust/kernel/sync/condvar.rs

@@ -72,8 +72,8 @@ pub use new_condvar;
 /// }
 ///
 /// /// Allocates a new boxed `Example`.
-/// fn new_example() -> Result<Pin<Box<Example>>> {
-///     Box::pin_init(pin_init!(Example {
+/// fn new_example() -> Result<Pin<KBox<Example>>> {
+///     KBox::pin_init(pin_init!(Example {
 ///         value <- new_mutex!(0),
 ///         value_changed <- new_condvar!(),
 ///     }), GFP_KERNEL)
@@ -95,7 +95,6 @@ pub struct CondVar {
 }
 
 // SAFETY: `CondVar` only uses a `struct wait_queue_head`, which is safe to use on any thread.
-#[allow(clippy::non_send_fields_in_send_ty)]
 unsafe impl Send for CondVar {}
 
 // SAFETY: `CondVar` only uses a `struct wait_queue_head`, which is safe to use on multiple threads

rust/kernel/sync/lock.rs

@@ -179,9 +179,9 @@ impl<'a, T: ?Sized, B: Backend> Guard<'a, T, B> {
         // SAFETY: The caller owns the lock, so it is safe to unlock it.
         unsafe { B::unlock(self.lock.state.get(), &self.state) };
 
-        // SAFETY: The lock was just unlocked above and is being relocked now.
-        let _relock =
-            ScopeGuard::new(|| unsafe { B::relock(self.lock.state.get(), &mut self.state) });
+        let _relock = ScopeGuard::new(||
+                // SAFETY: The lock was just unlocked above and is being relocked now.
+                unsafe { B::relock(self.lock.state.get(), &mut self.state) });
 
         cb()
     }

rust/kernel/sync/lock/mutex.rs

@@ -58,7 +58,7 @@ pub use new_mutex;
 /// }
 ///
 /// // Allocate a boxed `Example`.
-/// let e = Box::pin_init(Example::new(), GFP_KERNEL)?;
+/// let e = KBox::pin_init(Example::new(), GFP_KERNEL)?;
 /// assert_eq!(e.c, 10);
 /// assert_eq!(e.d.lock().a, 20);
 /// assert_eq!(e.d.lock().b, 30);

rust/kernel/sync/lock/spinlock.rs

@@ -56,7 +56,7 @@ pub use new_spinlock;
 /// }
 ///
 /// // Allocate a boxed `Example`.
-/// let e = Box::pin_init(Example::new(), GFP_KERNEL)?;
+/// let e = KBox::pin_init(Example::new(), GFP_KERNEL)?;
 /// assert_eq!(e.c, 10);
 /// assert_eq!(e.d.lock().a, 20);
 /// assert_eq!(e.d.lock().b, 30);

rust/kernel/sync/locked_by.rs

@@ -43,7 +43,7 @@ use core::{cell::UnsafeCell, mem::size_of, ptr};
 /// struct InnerDirectory {
 ///     /// The sum of the bytes used by all files.
 ///     bytes_used: u64,
-///     _files: Vec<File>,
+///     _files: KVec<File>,
 /// }
 ///
 /// struct Directory {

rust/kernel/types.rs

@@ -3,13 +3,11 @@
 //! Kernel types.
 
 use crate::init::{self, PinInit};
-use alloc::boxed::Box;
 use core::{
     cell::UnsafeCell,
     marker::{PhantomData, PhantomPinned},
     mem::{ManuallyDrop, MaybeUninit},
     ops::{Deref, DerefMut},
-    pin::Pin,
     ptr::NonNull,
 };
 
@@ -71,54 +69,6 @@ pub trait ForeignOwnable: Sized {
     }
 }
 
-impl<T: 'static> ForeignOwnable for Box<T> {
-    type Borrowed<'a> = &'a T;
-
-    fn into_foreign(self) -> *const core::ffi::c_void {
-        Box::into_raw(self) as _
-    }
-
-    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
-        // SAFETY: The safety requirements for this function ensure that the object is still alive,
-        // so it is safe to dereference the raw pointer.
-        // The safety requirements of `from_foreign` also ensure that the object remains alive for
-        // the lifetime of the returned value.
-        unsafe { &*ptr.cast() }
-    }
-
-    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
-        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
-        // call to `Self::into_foreign`.
-        unsafe { Box::from_raw(ptr as _) }
-    }
-}
-
-impl<T: 'static> ForeignOwnable for Pin<Box<T>> {
-    type Borrowed<'a> = Pin<&'a T>;
-
-    fn into_foreign(self) -> *const core::ffi::c_void {
-        // SAFETY: We are still treating the box as pinned.
-        Box::into_raw(unsafe { Pin::into_inner_unchecked(self) }) as _
-    }
-
-    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> Pin<&'a T> {
-        // SAFETY: The safety requirements for this function ensure that the object is still alive,
-        // so it is safe to dereference the raw pointer.
-        // The safety requirements of `from_foreign` also ensure that the object remains alive for
-        // the lifetime of the returned value.
-        let r = unsafe { &*ptr.cast() };
-
-        // SAFETY: This pointer originates from a `Pin<Box<T>>`.
-        unsafe { Pin::new_unchecked(r) }
-    }
-
-    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
-        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
-        // call to `Self::into_foreign`.
-        unsafe { Pin::new_unchecked(Box::from_raw(ptr as _)) }
-    }
-}
-
 impl ForeignOwnable for () {
     type Borrowed<'a> = ();
 
@@ -185,7 +135,7 @@ impl ForeignOwnable for () {
 /// # use kernel::types::ScopeGuard;
 /// fn example3(arg: bool) -> Result {
 ///     let mut vec =
-///         ScopeGuard::new_with_data(Vec::new(), |v| pr_info!("vec had {} elements\n", v.len()));
+///         ScopeGuard::new_with_data(KVec::new(), |v| pr_info!("vec had {} elements\n", v.len()));
 ///
 ///     vec.push(10u8, GFP_KERNEL)?;
 ///     if arg {
@@ -225,7 +175,7 @@ impl<T, F: FnOnce(T)> ScopeGuard<T, F> {
 impl ScopeGuard<(), fn(())> {
     /// Creates a new guarded object with the given cleanup function.
     pub fn new(cleanup: impl FnOnce()) -> ScopeGuard<(), impl FnOnce(())> {
-        ScopeGuard::new_with_data((), move |_| cleanup())
+        ScopeGuard::new_with_data((), move |()| cleanup())
     }
 }
 
@@ -426,6 +376,7 @@ impl<T: AlwaysRefCounted> ARef<T> {
     ///
     /// struct Empty {}
     ///
+    /// # // SAFETY: TODO.
     /// unsafe impl AlwaysRefCounted for Empty {
     ///     fn inc_ref(&self) {}
     ///     unsafe fn dec_ref(_obj: NonNull<Self>) {}
@@ -433,6 +384,7 @@ impl<T: AlwaysRefCounted> ARef<T> {
     ///
     /// let mut data = Empty {};
     /// let ptr = NonNull::<Empty>::new(&mut data as *mut _).unwrap();
+    /// # // SAFETY: TODO.
     /// let data_ref: ARef<Empty> = unsafe { ARef::from_raw(ptr) };
     /// let raw_ptr: NonNull<Empty> = ARef::into_raw(data_ref);
     ///
@@ -497,21 +449,23 @@ pub enum Either<L, R> {
 /// All bit-patterns must be valid for this type. This type must not have interior mutability.
 pub unsafe trait FromBytes {}
 
-// SAFETY: All bit patterns are acceptable values of the types below.
-unsafe impl FromBytes for u8 {}
-unsafe impl FromBytes for u16 {}
-unsafe impl FromBytes for u32 {}
-unsafe impl FromBytes for u64 {}
-unsafe impl FromBytes for usize {}
-unsafe impl FromBytes for i8 {}
-unsafe impl FromBytes for i16 {}
-unsafe impl FromBytes for i32 {}
-unsafe impl FromBytes for i64 {}
-unsafe impl FromBytes for isize {}
-// SAFETY: If all bit patterns are acceptable for individual values in an array, then all bit
-// patterns are also acceptable for arrays of that type.
-unsafe impl<T: FromBytes> FromBytes for [T] {}
-unsafe impl<T: FromBytes, const N: usize> FromBytes for [T; N] {}
+macro_rules! impl_frombytes {
+    ($($({$($generics:tt)*})? $t:ty, )*) => {
+        // SAFETY: Safety comments written in the macro invocation.
+        $(unsafe impl$($($generics)*)? FromBytes for $t {})*
+    };
+}
+
+impl_frombytes! {
+    // SAFETY: All bit patterns are acceptable values of the types below.
+    u8, u16, u32, u64, usize,
+    i8, i16, i32, i64, isize,
+
+    // SAFETY: If all bit patterns are acceptable for individual values in an array, then all bit
+    // patterns are also acceptable for arrays of that type.
+    {<T: FromBytes>} [T],
+    {<T: FromBytes, const N: usize>} [T; N],
+}
 
 /// Types that can be viewed as an immutable slice of initialized bytes.
 ///
@@ -530,25 +484,6 @@ unsafe impl<T: FromBytes, const N: usize> FromBytes for [T; N] {}
 /// mutability.
 pub unsafe trait AsBytes {}
 
-// SAFETY: Instances of the following types have no uninitialized portions.
-unsafe impl AsBytes for u8 {}
-unsafe impl AsBytes for u16 {}
-unsafe impl AsBytes for u32 {}
-unsafe impl AsBytes for u64 {}
-unsafe impl AsBytes for usize {}
-unsafe impl AsBytes for i8 {}
-unsafe impl AsBytes for i16 {}
-unsafe impl AsBytes for i32 {}
-unsafe impl AsBytes for i64 {}
-unsafe impl AsBytes for isize {}
-unsafe impl AsBytes for bool {}
-unsafe impl AsBytes for char {}
-unsafe impl AsBytes for str {}
-// SAFETY: If individual values in an array have no uninitialized portions, then the array itself
-// does not have any uninitialized portions either.
-unsafe impl<T: AsBytes> AsBytes for [T] {}
-unsafe impl<T: AsBytes, const N: usize> AsBytes for [T; N] {}
-
 /// Zero-sized type to mark types not [`Send`].
 ///
 /// Add this type as a field to your struct if your type should not be sent to a different task.
@@ -569,3 +504,24 @@ pub type NotThreadSafe = PhantomData<*mut ()>;
 /// [`NotThreadSafe`]: type@NotThreadSafe
 #[allow(non_upper_case_globals)]
 pub const NotThreadSafe: NotThreadSafe = PhantomData;
+
+macro_rules! impl_asbytes {
+    ($($({$($generics:tt)*})? $t:ty, )*) => {
+        // SAFETY: Safety comments written in the macro invocation.
+        $(unsafe impl$($($generics)*)? AsBytes for $t {})*
+    };
+}
+
+impl_asbytes! {
+    // SAFETY: Instances of the following types have no uninitialized portions.
+    u8, u16, u32, u64, usize,
+    i8, i16, i32, i64, isize,
+    bool,
+    char,
+    str,
+
+    // SAFETY: If individual values in an array have no uninitialized portions, then the array
+    // itself does not have any uninitialized portions either.
+    {<T: AsBytes>} [T],
+    {<T: AsBytes, const N: usize>} [T; N],
+}

rust/kernel/uaccess.rs

@@ -11,7 +11,6 @@ use crate::{
     prelude::*,
     types::{AsBytes, FromBytes},
 };
-use alloc::vec::Vec;
 use core::ffi::{c_ulong, c_void};
 use core::mem::{size_of, MaybeUninit};
 
@@ -46,7 +45,6 @@ pub type UserPtr = usize;
 /// every byte in the region.
 ///
 /// ```no_run
-/// use alloc::vec::Vec;
 /// use core::ffi::c_void;
 /// use kernel::error::Result;
 /// use kernel::uaccess::{UserPtr, UserSlice};
@@ -54,7 +52,7 @@ pub type UserPtr = usize;
 /// fn bytes_add_one(uptr: UserPtr, len: usize) -> Result<()> {
 ///     let (read, mut write) = UserSlice::new(uptr, len).reader_writer();
 ///
-///     let mut buf = Vec::new();
+///     let mut buf = KVec::new();
 ///     read.read_all(&mut buf, GFP_KERNEL)?;
 ///
 ///     for b in &mut buf {
@@ -69,7 +67,6 @@ pub type UserPtr = usize;
 /// Example illustrating a TOCTOU (time-of-check to time-of-use) bug.
 ///
 /// ```no_run
-/// use alloc::vec::Vec;
 /// use core::ffi::c_void;
 /// use kernel::error::{code::EINVAL, Result};
 /// use kernel::uaccess::{UserPtr, UserSlice};
@@ -78,21 +75,21 @@ pub type UserPtr = usize;
 /// fn is_valid(uptr: UserPtr, len: usize) -> Result<bool> {
 ///     let read = UserSlice::new(uptr, len).reader();
 ///
-///     let mut buf = Vec::new();
+///     let mut buf = KVec::new();
 ///     read.read_all(&mut buf, GFP_KERNEL)?;
 ///
 ///     todo!()
 /// }
 ///
 /// /// Returns the bytes behind this user pointer if they are valid.
-/// fn get_bytes_if_valid(uptr: UserPtr, len: usize) -> Result<Vec<u8>> {
+/// fn get_bytes_if_valid(uptr: UserPtr, len: usize) -> Result<KVec<u8>> {
 ///     if !is_valid(uptr, len)? {
 ///         return Err(EINVAL);
 ///     }
 ///
 ///     let read = UserSlice::new(uptr, len).reader();
 ///
-///     let mut buf = Vec::new();
+///     let mut buf = KVec::new();
 ///     read.read_all(&mut buf, GFP_KERNEL)?;
 ///
 ///     // THIS IS A BUG! The bytes could have changed since we checked them.
@@ -130,7 +127,7 @@ impl UserSlice {
     /// Reads the entirety of the user slice, appending it to the end of the provided buffer.
     ///
     /// Fails with [`EFAULT`] if the read happens on a bad address.
-    pub fn read_all(self, buf: &mut Vec<u8>, flags: Flags) -> Result {
+    pub fn read_all(self, buf: &mut KVec<u8>, flags: Flags) -> Result {
         self.reader().read_all(buf, flags)
     }
 
@@ -291,9 +288,9 @@ impl UserSliceReader {
     /// Reads the entirety of the user slice, appending it to the end of the provided buffer.
     ///
     /// Fails with [`EFAULT`] if the read happens on a bad address.
-    pub fn read_all(mut self, buf: &mut Vec<u8>, flags: Flags) -> Result {
+    pub fn read_all(mut self, buf: &mut KVec<u8>, flags: Flags) -> Result {
         let len = self.length;
-        VecExt::<u8>::reserve(buf, len, flags)?;
+        buf.reserve(len, flags)?;
 
         // The call to `try_reserve` was successful, so the spare capacity is at least `len` bytes
         // long.

rust/kernel/workqueue.rs

@@ -216,7 +216,7 @@ impl Queue {
             func: Some(func),
         });
 
-        self.enqueue(Box::pin_init(init, flags).map_err(|_| AllocError)?);
+        self.enqueue(KBox::pin_init(init, flags).map_err(|_| AllocError)?);
         Ok(())
     }
 }
@@ -239,9 +239,9 @@ impl<T> ClosureWork<T> {
 }
 
 impl<T: FnOnce()> WorkItem for ClosureWork<T> {
-    type Pointer = Pin<Box<Self>>;
+    type Pointer = Pin<KBox<Self>>;
 
-    fn run(mut this: Pin<Box<Self>>) {
+    fn run(mut this: Pin<KBox<Self>>) {
         if let Some(func) = this.as_mut().project().take() {
             (func)()
         }
@@ -297,7 +297,7 @@ pub unsafe trait RawWorkItem<const ID: u64> {
 
 /// Defines the method that should be called directly when a work item is executed.
 ///
-/// This trait is implemented by `Pin<Box<T>>` and [`Arc<T>`], and is mainly intended to be
+/// This trait is implemented by `Pin<KBox<T>>` and [`Arc<T>`], and is mainly intended to be
 /// implemented for smart pointer types. For your own structs, you would implement [`WorkItem`]
 /// instead. The [`run`] method on this trait will usually just perform the appropriate
 /// `container_of` translation and then call into the [`run`][WorkItem::run] method from the
@@ -329,7 +329,7 @@ pub unsafe trait WorkItemPointer<const ID: u64>: RawWorkItem<ID> {
 /// This trait is used when the `work_struct` field is defined using the [`Work`] helper.
 pub trait WorkItem<const ID: u64 = 0> {
     /// The pointer type that this struct is wrapped in. This will typically be `Arc<Self>` or
-    /// `Pin<Box<Self>>`.
+    /// `Pin<KBox<Self>>`.
     type Pointer: WorkItemPointer<ID>;
 
     /// The method that should be called when this work item is executed.
@@ -366,7 +366,6 @@ unsafe impl<T: ?Sized, const ID: u64> Sync for Work<T, ID> {}
 impl<T: ?Sized, const ID: u64> Work<T, ID> {
     /// Creates a new instance of [`Work`].
     #[inline]
-    #[allow(clippy::new_ret_no_self)]
     pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self>
     where
         T: WorkItem<ID>,
@@ -520,13 +519,14 @@ impl_has_work! {
     impl{T} HasWork<Self> for ClosureWork<T> { self.work }
 }
 
+// SAFETY: TODO.
 unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Arc<T>
 where
     T: WorkItem<ID, Pointer = Self>,
     T: HasWork<T, ID>,
 {
     unsafe extern "C" fn run(ptr: *mut bindings::work_struct) {
-        // SAFETY: The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
+        // The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
         let ptr = ptr as *mut Work<T, ID>;
         // SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`.
         let ptr = unsafe { T::work_container_of(ptr) };
@@ -537,6 +537,7 @@ where
     }
 }
 
+// SAFETY: TODO.
 unsafe impl<T, const ID: u64> RawWorkItem<ID> for Arc<T>
 where
     T: WorkItem<ID, Pointer = Self>,
@@ -565,18 +566,19 @@ where
     }
 }
 
-unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Pin<Box<T>>
+// SAFETY: TODO.
+unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Pin<KBox<T>>
 where
     T: WorkItem<ID, Pointer = Self>,
     T: HasWork<T, ID>,
 {
     unsafe extern "C" fn run(ptr: *mut bindings::work_struct) {
-        // SAFETY: The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
+        // The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
         let ptr = ptr as *mut Work<T, ID>;
         // SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`.
         let ptr = unsafe { T::work_container_of(ptr) };
         // SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership.
-        let boxed = unsafe { Box::from_raw(ptr) };
+        let boxed = unsafe { KBox::from_raw(ptr) };
         // SAFETY: The box was already pinned when it was enqueued.
         let pinned = unsafe { Pin::new_unchecked(boxed) };
 
@@ -584,7 +586,8 @@ where
     }
 }
 
-unsafe impl<T, const ID: u64> RawWorkItem<ID> for Pin<Box<T>>
+// SAFETY: TODO.
+unsafe impl<T, const ID: u64> RawWorkItem<ID> for Pin<KBox<T>>
 where
     T: WorkItem<ID, Pointer = Self>,
     T: HasWork<T, ID>,
@@ -598,9 +601,9 @@ where
         // SAFETY: We're not going to move `self` or any of its fields, so its okay to temporarily
         // remove the `Pin` wrapper.
         let boxed = unsafe { Pin::into_inner_unchecked(self) };
-        let ptr = Box::into_raw(boxed);
+        let ptr = KBox::into_raw(boxed);
 
-        // SAFETY: Pointers into a `Box` point at a valid value.
+        // SAFETY: Pointers into a `KBox` point at a valid value.
         let work_ptr = unsafe { T::raw_get_work(ptr) };
         // SAFETY: `raw_get_work` returns a pointer to a valid value.
         let work_ptr = unsafe { Work::raw_get(work_ptr) };

rust/macros/lib.rs

@@ -242,8 +242,8 @@ pub fn concat_idents(ts: TokenStream) -> TokenStream {
 /// #[pin_data]
 /// struct DriverData {
 ///     #[pin]
-///     queue: Mutex<Vec<Command>>,
-///     buf: Box<[u8; 1024 * 1024]>,
+///     queue: Mutex<KVec<Command>>,
+///     buf: KBox<[u8; 1024 * 1024]>,
 /// }
 /// ```
 ///
@@ -251,8 +251,8 @@ pub fn concat_idents(ts: TokenStream) -> TokenStream {
 /// #[pin_data(PinnedDrop)]
 /// struct DriverData {
 ///     #[pin]
-///     queue: Mutex<Vec<Command>>,
-///     buf: Box<[u8; 1024 * 1024]>,
+///     queue: Mutex<KVec<Command>>,
+///     buf: KBox<[u8; 1024 * 1024]>,
 ///     raw_info: *mut Info,
 /// }
 ///
@@ -281,8 +281,8 @@ pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream {
 /// #[pin_data(PinnedDrop)]
 /// struct DriverData {
 ///     #[pin]
-///     queue: Mutex<Vec<Command>>,
-///     buf: Box<[u8; 1024 * 1024]>,
+///     queue: Mutex<KVec<Command>>,
+///     buf: KBox<[u8; 1024 * 1024]>,
 ///     raw_info: *mut Info,
 /// }
 ///

rust/uapi/lib.rs

@@ -14,6 +14,7 @@
 #![cfg_attr(test, allow(unsafe_op_in_unsafe_fn))]
 #![allow(
     clippy::all,
+    clippy::undocumented_unsafe_blocks,
     dead_code,
     missing_docs,
     non_camel_case_types,

samples/rust/rust_minimal.rs

@@ -13,7 +13,7 @@ module! {
 }
 
 struct RustMinimal {
-    numbers: Vec<i32>,
+    numbers: KVec<i32>,
 }
 
 impl kernel::Module for RustMinimal {
@@ -21,7 +21,7 @@ impl kernel::Module for RustMinimal {
         pr_info!("Rust minimal sample (init)\n");
         pr_info!("Am I built-in? {}\n", !cfg!(MODULE));
 
-        let mut numbers = Vec::new();
+        let mut numbers = KVec::new();
         numbers.push(72, GFP_KERNEL)?;
         numbers.push(108, GFP_KERNEL)?;
         numbers.push(200, GFP_KERNEL)?;

samples/rust/rust_print_main.rs

@@ -15,6 +15,7 @@ module! {
 
 struct RustPrint;
 
+#[expect(clippy::disallowed_macros)]
 fn arc_print() -> Result {
     use kernel::sync::*;
 

scripts/Makefile.build

@@ -259,7 +259,7 @@ $(obj)/%.lst: $(obj)/%.c FORCE
 # Compile Rust sources (.rs)
 # ---------------------------------------------------------------------------
 
-rust_allowed_features := arbitrary_self_types,asm_const,asm_goto,new_uninit
+rust_allowed_features := arbitrary_self_types,asm_const,asm_goto,lint_reasons,new_uninit
 
 # `--out-dir` is required to avoid temporaries being created by `rustc` in the
 # current working directory, which may be not accessible in the out-of-tree