Currently, since all the architectures that support Rust all have
CONFIG_ARCH_SUPPORTS_ATOMIC_RMW selected, the helpers of atomic
load/store on i8 and i16 relies on CONFIG_ARCH_SUPPORTS_ATOMIC_RMW=y.
It's generally fine since most of architectures support that.
The plan for CONFIG_ARCH_SUPPORTS_ATOMIC_RMW=n architectures is adding
their (probably lock-based) atomic load/store for i8 and i16 as their
atomic_{read,set}() and atomic64_{read,set}() counterpart when they
plans to support Rust.
Hence use a statis_assert!() to check this and remind the future us the
need of the helpers. This is more clear than the #[cfg] on impl blocks
of i8 and i16.
Suggested-by: Dirk Behme <[email protected]>
Suggested-by: Benno Lossin <[email protected]>
Signed-off-by: Boqun Feng <[email protected]>
---
rust/kernel/sync/atomic/internal.rs | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/rust/kernel/sync/atomic/internal.rs
b/rust/kernel/sync/atomic/internal.rs
index 0dac58bca2b3..ef516bcb02ee 100644
--- a/rust/kernel/sync/atomic/internal.rs
+++ b/rust/kernel/sync/atomic/internal.rs
@@ -37,16 +37,23 @@ pub trait AtomicImpl: Sized + Send + Copy + private::Sealed
{
type Delta;
}
-// The current helpers of load/store uses `{WRITE,READ}_ONCE()` hence the
atomicity is only
-// guaranteed against read-modify-write operations if the architecture
supports native atomic RmW.
-#[cfg(CONFIG_ARCH_SUPPORTS_ATOMIC_RMW)]
+// The current helpers of load/store of atomic `i8` and `i16` use
`{WRITE,READ}_ONCE()` hence the
+// atomicity is only guaranteed against read-modify-write operations if the
architecture supports
+// native atomic RmW.
+//
+// In the future when a CONFIG_ARCH_SUPPORTS_ATOMIC_RMW=n architecture plans
to support Rust, the
+// load/store helpers that guarantee atomicity against RmW operations (usually
via a lock) need to
+// be added.
+crate::static_assert!(
+ cfg!(CONFIG_ARCH_SUPPORTS_ATOMIC_RMW),
+ "The current implementation of atomic i8/i16/ptr relies on the architecure
being \
+ ARCH_SUPPORTS_ATOMIC_RMW"
+);
+
impl AtomicImpl for i8 {
type Delta = Self;
}
-// The current helpers of load/store uses `{WRITE,READ}_ONCE()` hence the
atomicity is only
-// guaranteed against read-modify-write operations if the architecture
supports native atomic RmW.
-#[cfg(CONFIG_ARCH_SUPPORTS_ATOMIC_RMW)]
impl AtomicImpl for i16 {
type Delta = Self;
}
--
2.51.0
