document rcu barrier

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/doc/rcu-api.txt b/doc/rcu-api.txt
index 2a7e73443143d086c4b15adf504fb80b28235540..b64731671e3a78fd15b669e9927f646f45235852 100644 (file)
--- a/doc/rcu-api.txt
+++ b/doc/rcu-api.txt
@@ -62,6 +62,15 @@ void call_rcu(struct rcu_head *head,
        call_rcu should be called from registered RCU read-side threads.
        For the QSBR flavor, the caller should be online.
 
+void rcu_barrier(void);
+
+       Wait for all call_rcu() work initiated prior to rcu_barrier() by
+       _any_ thread on the system to have completed before rcu_barrier()
+       returns. rcu_barrier() should never be called from a call_rcu()
+       thread. This function can be used, for instance, to ensure that
+       all memory reclaim involving a shared object has completed
+       before allowing dlclose() of this shared object to complete.
+
 struct call_rcu_data *create_call_rcu_data(unsigned long flags,
                                           int cpu_affinity);