ipc,rcu: Convert call_rcu(ipc_immediate_free) to kfree_rcu()

The rcu callback ipc_immediate_free() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(ipc_immediate_free).
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

ipc/util.c

@@ -579,19 +579,6 @@ static void ipc_schedule_free(struct rcu_head *head)
 	schedule_work(&sched->work);
 }
 
-/**
- * ipc_immediate_free - free ipc + rcu space
- * @head: RCU callback structure that contains pointer to be freed
- *
- * Free from the RCU callback context.
- */
-static void ipc_immediate_free(struct rcu_head *head)
-{
-	struct ipc_rcu_grace *free =
-		container_of(head, struct ipc_rcu_grace, rcu);
-	kfree(free);
-}
-
 void ipc_rcu_putref(void *ptr)
 {
 	if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
@@ -601,8 +588,7 @@ void ipc_rcu_putref(void *ptr)
 		call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
 				ipc_schedule_free);
 	} else {
-		call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
-				ipc_immediate_free);
+		kfree_rcu(container_of(ptr, struct ipc_rcu_grace, data), rcu);
 	}
 }