From d8973c47544371613313ecb9a8c3e7b244aa9bbf Mon Sep 17 00:00:00 2001 From: Philipp Stanner Date: Wed, 5 Aug 2026 16:59:45 +0200 Subject: [PATCH] rust: sync: Add abstraction for rcu_barrier() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit rcu_barrier() is a frequently used C function which is always safe to be called. Add a safe abstraction for rcu_barrier(). Tested-by: Daniel Almeida Signed-off-by: Philipp Stanner Acked-by: Gary Guo Reviewed-by: Onur Özkan Acked-by: Danilo Krummrich Link: https://patch.msgid.link/20260805145949.938505-5-phasta@kernel.org [ Formatted documentation. Sorted tags. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/sync/rcu.rs | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/rust/kernel/sync/rcu.rs b/rust/kernel/sync/rcu.rs index a32bef6e490b..42d1b26a2143 100644 --- a/rust/kernel/sync/rcu.rs +++ b/rust/kernel/sync/rcu.rs @@ -50,3 +50,23 @@ fn drop(&mut self) { pub fn read_lock() -> Guard { Guard::new() } + +/// Wait until all in-flight `call_rcu()` callbacks complete. +/// +/// Note that this primitive does not necessarily wait for an RCU grace period +/// to complete. For example, if there are no RCU callbacks queued anywhere +/// in the system, then [`rcu_barrier()`] is within its rights to return +/// immediately, without waiting for anything, much less an RCU grace period. +/// In fact, [`rcu_barrier()`] will normally not result in any RCU grace periods +/// beyond those that were already destined to be executed. +/// +/// In kernels built with `CONFIG_RCU_LAZY=y`, this function also hurries all +/// pending lazy RCU callbacks. +/// +/// Note that this is one of the RCU primitives which must not be called in +/// atomic context. +#[inline] +pub fn rcu_barrier() { + // SAFETY: `rcu_barrier()` is always safe to be called. It just might wait for a grace period. + unsafe { bindings::rcu_barrier() }; +}