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Given the macro scoping rules, all macros are rendered twice, in the
module and in the top-level of kernel crate.
Add `#[doc(hidden)]` to the macro definition and `#[doc(inline)]` to the
re-export inside `build_assert` module so the top-level items are hidden.
[ Sadly, because the definition is hidden, `rustdoc` decides to not list
them as re-exports in the `prelude` page anymore, even if we refer to
the not-actually-hidden item.
- Miguel ]
Acked-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Acked-by: Boqun Feng <boqun@kernel.org>
Signed-off-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260609142637.373347-1-gary@kernel.org
[ Kept a single declaration in the prelude, and reworded since they
already had `no_inline`. Removed other imports from `predefine` since
we now use the prelude. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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There are 6 individual Rust KUnit test suites (plus the doctests one). All
the tests are compiled unconditionally now, which adds ~200 kB to the
kernel image for me on x86_64. As Rust matures, this bloating will
inevitably grow.
Add Kconfig.test which includes a RUST_KUNIT_TESTS menu, and all
individual tests under it.
As usual, new tests are all enabled if KUNIT_ALL_TESTS=y.
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Yury Norov <ynorov@nvidia.com>
Reviewed-by: David Gow <david@davidgow.net>
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260417031531.315281-3-ynorov@nvidia.com
[ Fixed capitalization. Used singular for "API" for consistency.
Reworded to clarify these are suites and that there exists
the doctests one (which is the biggest at the moment by
far). - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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The following patch makes usage of macros::kunit_tests crate conditional
on the corresponding configs. When the configs are disabled, compiler
warns on unused crate. So, embed it in unit test declaration.
Signed-off-by: Yury Norov <ynorov@nvidia.com>
Reviewed-by: David Gow <david@davidgow.net>
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260417031531.315281-2-ynorov@nvidia.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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In order to synchronize with C or external memory, atomic operations
over raw pointers are need. Although there is already an
`Atomic::from_ptr()` to provide a `&Atomic<T>`, it's more convenient to
have helpers that directly perform atomic operations on raw pointers.
Hence a few are added, which are basically an `Atomic::from_ptr().op()`
wrapper.
Note: for naming, since `atomic_xchg()` and `atomic_cmpxchg()` have a
conflict naming to 32bit C atomic xchg/cmpxchg, hence the helpers are
just named as `xchg()` and `cmpxchg()`. For `atomic_load()` and
`atomic_store()`, their 32bit C counterparts are `atomic_read()` and
`atomic_set()`, so keep the `atomic_` prefix.
[boqun: Fix typo spotted by Alice and fix broken sentence spotted by
Gary]
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260120115207.55318-3-boqun.feng@gmail.com
Link: https://patch.msgid.link/20260303201701.12204-11-boqun@kernel.org
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Add AtomicFlag type for boolean flags.
Document when AtomicFlag is generally preferable to Atomic<bool>: in
particular, when RMW operations such as xchg()/cmpxchg() may be used
and minimizing memory usage is not the top priority. On some
architectures without byte-sized RMW instructions, Atomic<bool> can be
slower for RMW operations.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: Boqun Feng <boqun@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260129122622.3896144-2-tomo@aliasing.net
Link: https://patch.msgid.link/20260303201701.12204-9-boqun@kernel.org
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Atomic pointer support is an important piece of synchronization
algorithm, e.g. RCU, hence provide the support for that.
Note that instead of relying on atomic_long or the implementation of
`Atomic<usize>`, a new set of helpers (atomic_ptr_*) is introduced for
atomic pointer specifically, this is because ptr2int casting would
lose the provenance of a pointer and even though in theory there are a
few tricks the provenance can be restored, it'll still be a simpler
implementation if C could provide atomic pointers directly. The side
effects of this approach are: we don't have the arithmetic and logical
operations for pointers yet and the current implementation only works
on ARCH_SUPPORTS_ATOMIC_RMW architectures, but these are implementation
issues and can be added later.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Link: https://patch.msgid.link/20260120140503.62804-3-boqun.feng@gmail.com
Link: https://patch.msgid.link/20260303201701.12204-8-boqun@kernel.org
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
"Lock debugging:
- Implement compiler-driven static analysis locking context checking,
using the upcoming Clang 22 compiler's context analysis features
(Marco Elver)
We removed Sparse context analysis support, because prior to
removal even a defconfig kernel produced 1,700+ context tracking
Sparse warnings, the overwhelming majority of which are false
positives. On an allmodconfig kernel the number of false positive
context tracking Sparse warnings grows to over 5,200... On the plus
side of the balance actual locking bugs found by Sparse context
analysis is also rather ... sparse: I found only 3 such commits in
the last 3 years. So the rate of false positives and the
maintenance overhead is rather high and there appears to be no
active policy in place to achieve a zero-warnings baseline to move
the annotations & fixers to developers who introduce new code.
Clang context analysis is more complete and more aggressive in
trying to find bugs, at least in principle. Plus it has a different
model to enabling it: it's enabled subsystem by subsystem, which
results in zero warnings on all relevant kernel builds (as far as
our testing managed to cover it). Which allowed us to enable it by
default, similar to other compiler warnings, with the expectation
that there are no warnings going forward. This enforces a
zero-warnings baseline on clang-22+ builds (Which are still limited
in distribution, admittedly)
Hopefully the Clang approach can lead to a more maintainable
zero-warnings status quo and policy, with more and more subsystems
and drivers enabling the feature. Context tracking can be enabled
for all kernel code via WARN_CONTEXT_ANALYSIS_ALL=y (default
disabled), but this will generate a lot of false positives.
( Having said that, Sparse support could still be added back,
if anyone is interested - the removal patch is still
relatively straightforward to revert at this stage. )
Rust integration updates: (Alice Ryhl, Fujita Tomonori, Boqun Feng)
- Add support for Atomic<i8/i16/bool> and replace most Rust native
AtomicBool usages with Atomic<bool>
- Clean up LockClassKey and improve its documentation
- Add missing Send and Sync trait implementation for SetOnce
- Make ARef Unpin as it is supposed to be
- Add __rust_helper to a few Rust helpers as a preparation for
helper LTO
- Inline various lock related functions to avoid additional function
calls
WW mutexes:
- Extend ww_mutex tests and other test-ww_mutex updates (John
Stultz)
Misc fixes and cleanups:
- rcu: Mark lockdep_assert_rcu_helper() __always_inline (Arnd
Bergmann)
- locking/local_lock: Include more missing headers (Peter Zijlstra)
- seqlock: fix scoped_seqlock_read kernel-doc (Randy Dunlap)
- rust: sync: Replace `kernel::c_str!` with C-Strings (Tamir
Duberstein)"
* tag 'locking-core-2026-02-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (90 commits)
locking/rwlock: Fix write_trylock_irqsave() with CONFIG_INLINE_WRITE_TRYLOCK
rcu: Mark lockdep_assert_rcu_helper() __always_inline
compiler-context-analysis: Remove __assume_ctx_lock from initializers
tomoyo: Use scoped init guard
crypto: Use scoped init guard
kcov: Use scoped init guard
compiler-context-analysis: Introduce scoped init guards
cleanup: Make __DEFINE_LOCK_GUARD handle commas in initializers
seqlock: fix scoped_seqlock_read kernel-doc
tools: Update context analysis macros in compiler_types.h
rust: sync: Replace `kernel::c_str!` with C-Strings
rust: sync: Inline various lock related methods
rust: helpers: Move #define __rust_helper out of atomic.c
rust: wait: Add __rust_helper to helpers
rust: time: Add __rust_helper to helpers
rust: task: Add __rust_helper to helpers
rust: sync: Add __rust_helper to helpers
rust: refcount: Add __rust_helper to helpers
rust: rcu: Add __rust_helper to helpers
rust: processor: Add __rust_helper to helpers
...
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For arm32, on a x86_64 builder, running the `rusttest` target yields:
error[E0080]: evaluation of constant value failed
--> rust/kernel/static_assert.rs:37:23
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37 | const _: () = ::core::assert!($condition $(,$arg)?);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'assertion failed: size_of::<isize>() == size_of::<isize_atomic_repr>()', rust/kernel/sync/atomic/predefine.rs:68:1
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::: rust/kernel/sync/atomic/predefine.rs:68:1
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68 | static_assert!(size_of::<isize>() == size_of::<isize_atomic_repr>());
| -------------------------------------------------------------------- in this macro invocation
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= note: this error originates in the macro `::core::assert` which comes from the expansion of the macro `static_assert` (in Nightly builds, run with -Z macro-backtrace for more info)
The reason is that `rusttest` runs on the host, so for e.g. a x86_64
builder `isize` is 64 bits but it is not a `CONFIG_64BIT` build.
Fix it by providing a stub for `rusttest` as usual.
Fixes: 84c6d36bcaf9 ("rust: sync: atomic: Add Atomic<{usize,isize}>")
Cc: stable@vger.kernel.org
Reviewed-by: Onur Özkan <work@onurozkan.dev>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20260123233432.22703-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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Add tests for Atomic<bool> operations.
Atomic<bool> does not fit into the existing u8/16/32/64 tests so
introduce a dedicated test for it.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20260101034922.2020334-3-fujita.tomonori@gmail.com
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Add `bool` support, `Atomic<bool>` by using `i8` as its underlying
representation.
Rust specifies that `bool` has size 1 and alignment 1 [1], so it
matches `i8` on layout; keep `static_assert!()` checks to enforce this
assumption at build time.
[boqun: Remove the unnecessary impl AtomicImpl for bool]
Link: https://doc.rust-lang.org/reference/types/boolean.html [1]
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20260101034922.2020334-2-fujita.tomonori@gmail.com
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Add atomic xchg and cmpxchg operation support for i8 and i16 types
with tests.
Note that since the current implementation of
Atomic::<{i8,i16}>::{load,store}() is READ_ONCE()/WRITE_ONCE()-based.
The atomicity between load/store and xchg/cmpxchg is only guaranteed if
the architecture has native RmW support, hence i8/i16 is currently
AtomicImpl only when CONFIG_ARCH_SUPPORTS_ATOMIC_RWM=y.
[boqun: Make i8/i16 AtomicImpl only when
CONFIG_ARCH_SUPPORTS_ATOMIC_RWM=y]
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20251228120546.1602275-4-fujita.tomonori@gmail.com
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Add minimum store_release/load_acquire tests.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20251211113826.1299077-5-fujita.tomonori@gmail.com
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Add atomic operation support for i8 and i16 types using volatile
read/write and smp_load_acquire/smp_store_release helpers.
[boqun: Adjust [1] to avoid introduction of
impl_atomic_only_load_and_store_ops!() in the middle]
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Link: https://lore.kernel.org/all/20251228120546.1602275-1-fujita.tomonori@gmail.com/ [1]
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20251211113826.1299077-4-fujita.tomonori@gmail.com
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Add generic atomic support for `usize` and `isize`. Note that instead of
mapping directly to `atomic_long_t`, the represention type
(`AtomicType::Repr`) is selected based on CONFIG_64BIT. This reduces
the necessity of creating `atomic_long_*` helpers, which could save
the binary size of kernel if inline helpers are not available. To do so,
an internal type `isize_atomic_repr` is defined, it's `i32` in 32bit
kernel and `i64` in 64bit kernel.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-9-boqun.feng@gmail.com/
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Add generic atomic support for basic unsigned types that have an
`AtomicImpl` with the same size and alignment.
Unit tests are added including Atomic<i32> and Atomic<i64>.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-8-boqun.feng@gmail.com/
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One important set of atomic operations is the arithmetic operations,
i.e. add(), sub(), fetch_add(), add_return(), etc. However it may not
make senses for all the types that `AtomicType` to have arithmetic
operations, for example a `Foo(u32)` may not have a reasonable add() or
sub(), plus subword types (`u8` and `u16`) currently don't have
atomic arithmetic operations even on C side and might not have them in
the future in Rust (because they are usually suboptimal on a few
architecures). Therefore the plan is to add a few subtraits of
`AtomicType` describing which types have and can do atomic arithemtic
operations.
One trait `AtomicAdd` is added, and only add() and fetch_add() are
added. The rest will be added in the future.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-7-boqun.feng@gmail.com/
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To provide using LKMM atomics for Rust code, a generic `Atomic<T>` is
added, currently `T` needs to be Send + Copy because these are the
straightforward usages and all basic types support this.
Implement `AtomicType` for `i32` and `i64`, and so far only basic
operations load() and store() are introduced.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-5-boqun.feng@gmail.com/
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