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
Rework the internal AtomicOps macro plumbing to generate per-type
implementations from a mapping list.
Capture the trait definition once and reuse it for both declaration
and per-type impl expansion to reduce duplication and keep future
extensions simple.
This is a preparatory refactor for enabling i8/i16 atomics cleanly.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20251228120546.1602275-2-fujita.tomonori@gmail.com
Add READ_ONCE/WRITE_ONCE based helpers for i8 and i16 types to support
relaxed atomic operations in Rust.
While relaxed operations could be implemented purely in Rust using
read_volatile() and write_volatile(), using C's READ_ONCE() and
WRITE_ONCE() macros ensures complete consistency with the kernel
memory model.
These helpers expose different symbol names than their C counterparts
so they are split into atomic_ext.c instead of atomic.c. The symbol
names; the names make the interface Rust/C clear, consistent with
i32/i64.
[boqun: Rename the functions from {load,store} to {read,set} to avoid
future adjustment]
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/20251211113826.1299077-3-fujita.tomonori@gmail.com
Add helper functions to expose smp_load_acquire() and
smp_store_release() for i8 and i16 types.
The smp_load_acquire() and smp_store_release() macros require type
information (sizeof) to generate appropriate architecture-specific
memory ordering instructions. Therefore, separate helper functions are
needed for each type size.
These helpers expose different symbol names than their C counterparts
so they are split into atomic_ext.c instead of atomic.c. The symbol
names; atomic_[i8|i16]_read_acquire and atomic_[i8|i16]_set_release
makes the interface Rust/C clear, consistent with i32/i64.
These helpers will be used by the upcoming Atomic<i8> and Atomic<i16>
implementation to provide proper Acquire/Release semantics across all
architectures.
[boqun: Rename the functions from {load,store} to {read,set} to avoid
future adjustment]
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/20251211113826.1299077-2-fujita.tomonori@gmail.com
Implement Send and Sync for SetOnce<T> to allow it to be used across
thread boundaries.
Send: SetOnce<T> can be transferred across threads when T: Send, as
the contained value is also transferred and will be dropped on the
destination thread.
Sync: SetOnce<T> can be shared across threads when T: Sync, as
as_ref() provides shared references &T and atomic operations ensure
proper synchronization. Since the inner T may be dropped on any
thread, we also require T: Send.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20251216000901.221375-1-fujita.tomonori@gmail.com
By introducing a new_static() constructor, the macro does not need to go
through MaybeUninit::uninit().assume_init(), which is a pattern that is
best avoided when possible.
The safety comment not only requires that the value is leaked, but also
that it is stored in the right portion of memory. This is so that the
lockdep static_obj() check will succeed when using this constructor. One
could argue that lockdep detects this scenario, so that safety
requirement isn't needed. However, it simplifies matters to require that
static_obj() will succeed and it's not a burdensome requirement on the
caller.
Suggested-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20250811-lock-class-key-cleanup-v3-1-b12967ee1ca2@google.com
Remove the explicit import of CStrExt. When CONFIG_PRINTK is disabled
this import causes a build error:
error: unused import: `crate::str::CStrExt`
--> rust/kernel/device.rs:17:5
|
17 | use crate::str::CStrExt as _;
| ^^^^^^^^^^^^^^^^^^^
|
= note: `-D unused-imports` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(unused_imports)]`
error: aborting due to 1 previous error
CStrExt is covered by prelude::* so the explicit import is redundant.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Fixes: 3b83f5d5e7 ("rust: replace `CStr` with `core::ffi::CStr`")
Link: https://patch.msgid.link/20260106000320.2593800-1-fujita.tomonori@gmail.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This got added with:
7454048db2 ("kbuild: Enable GCC diagnostic context for value-tracking warnings")
but clang does not have this option, so avoid passing it to bindgen.
[ Details about what the option does are in the commit above. Nathan
also expands on this:
Right, this does look correct, as this option is specific to GCC
for the purpose of exposing more information from GCC internals to
the user for understanding diagnostics better.
I checked that in Compiler Explorer GCC 15.2 doesn't have it, but GCC
trunk indeed has. - Miguel ]
Fixes: 7454048db2 ("kbuild: Enable GCC diagnostic context for value-tracking warnings")
Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org>
Link: https://patch.msgid.link/20251217224050.1186896-1-siddhesh@gotplt.org
[ Removed Cc: stable. Added title prefix. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Allow usage like `pr_info!("one + 1 = {}", one + 1)` to compile by
ensuring that a reference is taken to the entire expression.
[ The errors we would get otherwise look like:
error[E0277]: `kernel::fmt::Adapter<i32>` doesn't implement `core::fmt::Display`
--> ../samples/rust/rust_minimal.rs:34:9
|
34 | pr_info!("one + 1 = {}", one + 1);
| ^^^^^^^^^^^^^^^^^^^^--^^^^^^^^^^^
| | |
| | required by this formatting parameter
| `kernel::fmt::Adapter<i32>` cannot be formatted with the default formatter
|
= help: the trait `core::fmt::Display` is not implemented for `kernel::fmt::Adapter<i32>`
= note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
= help: the trait `core::fmt::Display` is implemented for `kernel::fmt::Adapter<&T>`
= note: this error originates in the macro `$crate::print_macro` which comes from the expansion of the macro `pr_info` (in Nightly builds, run with -Z macro-backtrace for more info)
- Miguel ]
Fixes: c5cf01ba8d ("rust: support formatting of foreign types")
Reported-by: Janne Grunau <j@jannau.net>
Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Custom.20formatting/near/566219493
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Janne Grunau <j@jannau.net>
Reviewed-by: Janne Grunau <j@jannau.net>
Link: https://patch.msgid.link/20260104-fmt-paren-v1-1-6b84bc0da78f@gmail.com
[ Added Signed-off-by back. Reworded title. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Alice Ryhl
FUJITA Tomonori
Danilo Krummrich
Ewan Chorynski
Marko Turk
Hsiu Che Yu
Siddhesh Poyarekar
Tamir Duberstein