[PATCH 6.18 093/122] rust: sync: refcount: always inline functions using build_assert with arguments

Greg Kroah-Hartman
2026-02-04T15:33:11Z

From: Alexandre Courbot <acourbot@nvidia.com>

commit d6ff6e870077ae0f01a6f860ca1e4a5a825dc032 upstream.

`build_assert` relies on the compiler to optimize out its error path.
Functions using it with its arguments must thus always be inlined,
otherwise the error path of `build_assert` might not be optimized out,
triggering a build error.

Cc: stable@vger.kernel.org
Fixes: bb38f35b35f9 ("rust: implement `kernel::sync::Refcount`")
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20251208-io-build-assert-v3-5-98aded02c1ea@nvidia.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
rust/kernel/sync/refcount.rs | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/sync/refcount.rs b/rust/kernel/sync/refcount.rs
index 19236a5bccde..6c7ae8b05a0b 100644
--- a/rust/kernel/sync/refcount.rs
+++ b/rust/kernel/sync/refcount.rs
@@ -23,7 +23,8 @@ impl Refcount {
/// Construct a new [`Refcount`] from an initial value.
///
/// The initial value should be non-saturated.
- #[inline]
+ // Always inline to optimize out error path of `build_assert`.
+ #[inline(always)]
pub fn new(value: i32) -> Self {
build_assert!(value >= 0, "initial value saturated");
// SAFETY: There are no safety requirements for this FFI call.
--
2.53.0