On 15/10/21 18:12, Greg Kurz wrote:
+/*
+ * NotifierList used to force an RCU grace period. Accessed under
+ * rcu_registry_lock.
+ */
+static NotifierList force_rcu_notifiers =
+ NOTIFIER_LIST_INITIALIZER(force_rcu_notifiers);
+
/*
* Check whether a quiescent state was crossed between the beginning of
* update_counter_and_wait and now.
@@ -107,6 +115,8 @@ static void wait_for_readers(void)
* get some extra futex wakeups.
*/
qatomic_set(&index->waiting, false);
+ } else if (qatomic_read(&in_drain_call_rcu)) {
+ notifier_list_notify(&force_rcu_notifiers, NULL);
}
}
You can put the notifier in struct rcu_reader_data---this way it doesn't
call all the notifiers but only those that are necessary to make progress.
While at it, I have a slight preference for a separate
rcu_add_force_rcu_notifier API, but I can be convinced otherwise. :)
Paolo
