linux/rust/kernel/alloc, branch v6.15

rust: allow Rust 1.87.0's `clippy::ptr_eq` lint

2025-05-06T22:11:02Z

Starting with Rust 1.87.0 (expected 2025-05-15) [1], Clippy may expand the `ptr_eq` lint, e.g.: error: use `core::ptr::eq` when comparing raw pointers --> rust/kernel/list.rs:438:12 | 438 | if self.first == item { | ^^^^^^^^^^^^^^^^^^ help: try: `core::ptr::eq(self.first, item)` | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ptr_eq = note: `-D clippy::ptr-eq` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::ptr_eq)]` It is expected that a PR to relax the lint will be backported [2] by the time Rust 1.87.0 releases, since the lint was considered too eager (at least by default) [3]. Thus allow the lint temporarily just in case. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: https://github.com/rust-lang/rust-clippy/pull/14339 [1] Link: https://github.com/rust-lang/rust-clippy/pull/14526 [2] Link: https://github.com/rust-lang/rust-clippy/issues/14525 [3] Link: https://lore.kernel.org/r/20250502140237.1659624-3-ojeda@kernel.org [ Converted to `allow`s since backport was confirmed. - Miguel ] Signed-off-by: Miguel Ojeda

Merge tag 'rust-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

2025-03-31T00:03:26Z

Pull Rust updates from Miguel Ojeda: "Toolchain and infrastructure: - Extract the 'pin-init' API from the 'kernel' crate and make it into a standalone crate. In order to do this, the contents are rearranged so that they can easily be kept in sync with the version maintained out-of-tree that other projects have started to use too (or plan to, like QEMU). This will reduce the maintenance burden for Benno, who will now have his own sub-tree, and will simplify future expected changes like the move to use 'syn' to simplify the implementation. - Add '#[test]'-like support based on KUnit. We already had doctests support based on KUnit, which takes the examples in our Rust documentation and runs them under KUnit. Now, we are adding the beginning of the support for "normal" tests, similar to those the '#[test]' tests in userspace Rust. For instance: #[kunit_tests(my_suite)] mod tests { #[test] fn my_test() { assert_eq!(1 + 1, 2); } } Unlike with doctests, the 'assert*!'s do not map to the KUnit assertion APIs yet. - Check Rust signatures at compile time for functions called from C by name. In particular, introduce a new '#[export]' macro that can be placed in the Rust function definition. It will ensure that the function declaration on the C side matches the signature on the Rust function: #[export] pub unsafe extern "C" fn my_function(a: u8, b: i32) -> usize { // ... } The macro essentially forces the compiler to compare the types of the actual Rust function and the 'bindgen'-processed C signature. These cases are rare so far. In the future, we may consider introducing another tool, 'cbindgen', to generate C headers automatically. Even then, having these functions explicitly marked may be a good idea anyway. - Enable the 'raw_ref_op' Rust feature: it is already stable, and allows us to use the new '&raw' syntax, avoiding a couple macros. After everyone has migrated, we will disallow the macros. - Pass the correct target to 'bindgen' on Usermode Linux. - Fix 'rusttest' build in macOS. 'kernel' crate: - New 'hrtimer' module: add support for setting up intrusive timers without allocating when starting the timer. Add support for 'Pin>', 'Arc<_>', 'Pin<&_>' and 'Pin<&mut _>' as pointer types for use with timer callbacks. Add support for setting clock source and timer mode. - New 'dma' module: add a simple DMA coherent allocator abstraction and a test sample driver. - 'list' module: make the linked list 'Cursor' point between elements, rather than at an element, which is more convenient to us and allows for cursors to empty lists; and document it with examples of how to perform common operations with the provided methods. - 'str' module: implement a few traits for 'BStr' as well as the 'strip_prefix()' method. - 'sync' module: add 'Arc::as_ptr'. - 'alloc' module: add 'Box::into_pin'. - 'error' module: extend the 'Result' documentation, including a few examples on different ways of handling errors, a warning about using methods that may panic, and links to external documentation. 'macros' crate: - 'module' macro: add the 'authors' key to support multiple authors. The original key will be kept until everyone has migrated. Documentation: - Add error handling sections. MAINTAINERS: - Add Danilo Krummrich as reviewer of the Rust "subsystem". - Add 'RUST [PIN-INIT]' entry with Benno Lossin as maintainer. It has its own sub-tree. - Add sub-tree for 'RUST [ALLOC]'. - Add 'DMA MAPPING HELPERS DEVICE DRIVER API [RUST]' entry with Abdiel Janulgue as primary maintainer. It will go through the sub-tree of the 'RUST [ALLOC]' entry. - Add 'HIGH-RESOLUTION TIMERS [RUST]' entry with Andreas Hindborg as maintainer. It has its own sub-tree. And a few other cleanups and improvements" * tag 'rust-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (71 commits) rust: dma: add `Send` implementation for `CoherentAllocation` rust: macros: fix `make rusttest` build on macOS rust: block: refactor to use `&raw mut` rust: enable `raw_ref_op` feature rust: uaccess: name the correct function rust: rbtree: fix comments referring to Box instead of KBox rust: hrtimer: add maintainer entry rust: hrtimer: add clocksource selection through `ClockId` rust: hrtimer: add `HrTimerMode` rust: hrtimer: implement `HrTimerPointer` for `Pin>` rust: alloc: add `Box::into_pin` rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&mut T>` rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&T>` rust: hrtimer: add `hrtimer::ScopedHrTimerPointer` rust: hrtimer: add `UnsafeHrTimerPointer` rust: hrtimer: allow timer restart from timer handler rust: str: implement `strip_prefix` for `BStr` rust: str: implement `AsRef` for `[u8]` and `BStr` rust: str: implement `Index` for `BStr` rust: str: implement `PartialEq` for `BStr` ...

Merge tag 'rust-hrtimer-for-v6.15-v3' of https://github.com/Rust-for-Linux/linux into rust-next

2025-03-25T22:41:14Z

Pull rust-hrtimer updates from Andreas Hindborg: "Introduce Rust support for the 'hrtimer' subsystem: - Add a way to use the 'hrtimer' subsystem from Rust. Rust code can now set up intrusive timers without allocating when starting the timer. - Add support for 'Pin>', 'Arc<_>', 'Pin<&_>' and 'Pin<&mut _>' as pointer types for use with timer callbacks. - Add support for setting clock source and timer mode. 'kernel' crate: - Add 'Arc::as_ptr' for converting an 'Arc' to a raw pointer. This is a dependency for the 'hrtimer' API. - Add 'Box::into_pin' for converting a 'Box<_>' into a 'Pin>' to align with Rust 'alloc'. This is a dependency for the 'hrtimer' API." * tag 'rust-hrtimer-for-v6.15-v3' of https://github.com/Rust-for-Linux/linux: rust: hrtimer: add maintainer entry rust: hrtimer: add clocksource selection through `ClockId` rust: hrtimer: add `HrTimerMode` rust: hrtimer: implement `HrTimerPointer` for `Pin>` rust: alloc: add `Box::into_pin` rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&mut T>` rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&T>` rust: hrtimer: add `hrtimer::ScopedHrTimerPointer` rust: hrtimer: add `UnsafeHrTimerPointer` rust: hrtimer: allow timer restart from timer handler rust: hrtimer: implement `HrTimerPointer` for `Arc` rust: sync: add `Arc::as_ptr` rust: hrtimer: introduce hrtimer support

rust: alloc: add `Box::into_pin`

2025-03-22T11:08:54Z

Add an associated function to convert a `Box` into a `Pin>`. Acked-by: Danilo Krummrich Reviewed-by: Benno Lossin Reviewed-by: Lyude Paul Link: https://lore.kernel.org/r/20250309-hrtimer-v3-v6-12-rc2-v12-9-73586e2bd5f1@kernel.org Signed-off-by: Andreas Hindborg

rust: make pin-init its own crate

2025-03-16T20:59:19Z

Rename relative paths inside of the crate to still refer to the same items, also rename paths inside of the kernel crate and adjust the build system to build the crate. [ Remove the `expect` (and thus the `lint_reasons` feature) since the tree now uses `quote!` from `rust/macros/export.rs`. Remove the `TokenStream` import removal, since it is now used as well. In addition, temporarily (i.e. just for this commit) use an `--extern force:alloc` to prevent an unknown `new_uninit` error in the `rustdoc` target. For context, please see a similar case in: https://lore.kernel.org/lkml/20240422090644.525520-1-ojeda@kernel.org/ And adjusted the message above. - Miguel ] Signed-off-by: Benno Lossin Reviewed-by: Fiona Behrens Tested-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250308110339.2997091-16-benno.lossin@proton.me Signed-off-by: Miguel Ojeda

rust: add `ZeroableOption` and implement it instead of `Zeroable` for `Option>`

2025-03-16T20:59:18Z

When making pin-init its own crate, `Zeroable` will no longer be defined by the kernel crate and thus implementing it for `Option>` is no longer possible due to the orphan rule. For this reason introduce a new `ZeroableOption` trait that circumvents this problem. Signed-off-by: Benno Lossin Reviewed-by: Fiona Behrens Reviewed-by: Andreas Hindborg Tested-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250308110339.2997091-11-benno.lossin@proton.me Signed-off-by: Miguel Ojeda

rust: pin-init: move impl `Zeroable` for `Opaque` and `Option>` into the kernel crate

2025-03-16T20:59:18Z

In order to make pin-init a standalone crate, move kernel-specific code directly into the kernel crate. Since `Opaque` and `KBox` are part of the kernel, move their `Zeroable` implementation into the kernel crate. Signed-off-by: Benno Lossin Tested-by: Andreas Hindborg Reviewed-by: Fiona Behrens Link: https://lore.kernel.org/r/20250308110339.2997091-10-benno.lossin@proton.me Signed-off-by: Miguel Ojeda

rust: pin-init: move `InPlaceInit` and impls of `InPlaceWrite` into the kernel crate

2025-03-16T20:59:18Z

In order to make pin-init a standalone crate, move kernel-specific code directly into the kernel crate. This includes the `InPlaceInit` trait, its implementations and the implementations of `InPlaceWrite` for `Arc` and `UniqueArc`. All of these use the kernel's error type which will become unavailable in pin-init. Signed-off-by: Benno Lossin Reviewed-by: Fiona Behrens Tested-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250308110339.2997091-9-benno.lossin@proton.me Signed-off-by: Miguel Ojeda

rust: alloc: make `ReallocFunc::call` inline

2025-03-06T19:49:06Z

This function can be called with different function pointers when different allocator (e.g. Kmalloc, Vmalloc, KVmalloc), however since this function is not polymorphic, only one instance is generated, and function pointers are used. Given that this function is called for any Rust-side allocation/deallocation, performance matters a lot, so making this function inlineable. This is discovered when doing helper inlining work, since it's discovered that even with helpers inlined, rust_helper_ symbols are still present in final vmlinux binary, and it turns out this function is inhibiting the inlining, and introducing indirect function calls. Signed-off-by: Gary Guo Acked-by: Danilo Krummrich Reviewed-by: Boqun Feng Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250105194054.545201-4-gary@garyguo.net Signed-off-by: Miguel Ojeda

rust: alloc: satisfy POSIX alignment requirement

2025-03-05T22:57:48Z

ISO C's `aligned_alloc` is partially implementation-defined; on some systems it inherits stricter requirements from POSIX's `posix_memalign`. This causes the call added in commit dd09538fb409 ("rust: alloc: implement `Cmalloc` in module allocator_test") to fail on macOS because it doesn't meet the requirements of `posix_memalign`. Adjust the call to meet the POSIX requirement and add a comment. This fixes failures in `make rusttest` on macOS. Acked-by: Danilo Krummrich Cc: stable@vger.kernel.org Fixes: dd09538fb409 ("rust: alloc: implement `Cmalloc` in module allocator_test") Signed-off-by: Tamir Duberstein Reviewed-by: Gary Guo Link: https://lore.kernel.org/r/20250213-aligned-alloc-v7-1-d2a2d0be164b@gmail.com [ Added Cc: stable. - Miguel ] Signed-off-by: Miguel Ojeda