[tip: locking/core] rust: sync: Add abstraction for synchronize_rcu()

[tip-bot2 for Philipp Stanner]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     1fb92e0625596985b3941925afe7906fef41214b
Gitweb:        https://git.kernel.org/tip/1fb92e0625596985b3941925afe7906fef41214b
Author:        Philipp Stanner <phasta@xxxxxxxxxx>
AuthorDate:    Wed, 24 Jun 2026 17:07:02 +02:00
Committer:     Boqun Feng <boqun@xxxxxxxxxx>
CommitterDate: Tue, 04 Aug 2026 05:52:53 -07:00

rust: sync: Add abstraction for synchronize_rcu()

synchronize_rcu() is a frequently used C function which is always safe
to be called.

Add a safe abstraction for synchronize_rcu().

Signed-off-by: Philipp Stanner <phasta@xxxxxxxxxx>
Reviewed-by: Onur Özkan <work@xxxxxxxxxxxxx>
Reviewed-by: Danilo Krummrich <dakr@xxxxxxxxxx>
Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>
[boqun: Fix rustdoc reported by kernel test robot <lkp@xxxxxxxxx>]
Signed-off-by: Boqun Feng <boqun@xxxxxxxxxx>
Link: https://patch.msgid.link/20260624150704.1504001-3-phasta@xxxxxxxxxx
---
 rust/kernel/sync/rcu.rs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/rust/kernel/sync/rcu.rs b/rust/kernel/sync/rcu.rs
index a32bef6..d867240 100644
--- a/rust/kernel/sync/rcu.rs
+++ b/rust/kernel/sync/rcu.rs
@@ -50,3 +50,19 @@ impl Drop for Guard {
 pub fn read_lock() -> Guard {
     Guard::new()
 }
+
+/// Wait for one RCU grace period.
+///
+/// Waits for all RCU read-side critical sections (such as those established by
+/// a [`Guard`]) at the moment of the function call to finish.
+///
+/// Does not prevent new read-side critical sections from starting, which may
+/// begin and run while this call is blocking.
+///
+/// Note that this is one of the RCU primitives which must not be called in
+/// atomic context.
+#[inline]
+pub fn synchronize_rcu() {
+    // SAFETY: `synchronize_rcu()` is always safe to be called from process context.
+    unsafe { bindings::synchronize_rcu() };
+}