+/*
+ * Return the number of RCU batches processed thus far. Useful
+ * for debug and statistics.
+ */
+long rcu_batches_completed(void)
+{
+ return rcu_ctrlblk.completed;
+}
+
+static void rcu_barrier_callback(struct rcu_head *notused)
+{
+ if (atomic_dec_and_test(&rcu_barrier_cpu_count))
+ complete(&rcu_barrier_completion);
+}
+
+/*
+ * Called with preemption disabled, and from cross-cpu IRQ context.
+ */
+static void rcu_barrier_func(void *notused)
+{
+ int cpu = smp_processor_id();
+ struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
+ struct rcu_head *head;
+
+ head = &rdp->barrier;
+ atomic_inc(&rcu_barrier_cpu_count);
+ call_rcu(head, rcu_barrier_callback);
+}
+
+/**
+ * rcu_barrier - Wait until all the in-flight RCUs are complete.
+ */
+void rcu_barrier(void)
+{
+ BUG_ON(in_interrupt());
+ /* Take cpucontrol semaphore to protect against CPU hotplug */
+ down(&rcu_barrier_sema);
+ init_completion(&rcu_barrier_completion);
+ atomic_set(&rcu_barrier_cpu_count, 0);
+ on_each_cpu(rcu_barrier_func, NULL, 0, 1);
+ wait_for_completion(&rcu_barrier_completion);
+ up(&rcu_barrier_sema);
+}
+EXPORT_SYMBOL_GPL(rcu_barrier);
+