rcu: convert uses of rcu_assign_pointer(x, NULL) to RCU_INIT_POINTER

When assigning a NULL value to an RCU protected pointer, no barrier
is needed. The rcu_assign_pointer, used to handle that but will soon
change to not handle the special case.

Convert all rcu_assign_pointer of NULL value.

//smpl
@@ expression P; @@

- rcu_assign_pointer(P, NULL)
+ RCU_INIT_POINTER(P, NULL)

// </smpl>

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 378b20b..065effd 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -231,7 +231,7 @@
 	     (iter = rtnl_dereference(*tp)) != NULL;
 	     tp = &iter->next) {
 		if (t == iter) {
-			rcu_assign_pointer(*tp, t->next);
+			RCU_INIT_POINTER(*tp, t->next);
 			break;
 		}
 	}
@@ -241,8 +241,8 @@
 {
 	struct ip_tunnel __rcu **tp = ipip_bucket(ipn, t);
 
-	rcu_assign_pointer(t->next, rtnl_dereference(*tp));
-	rcu_assign_pointer(*tp, t);
+	RCU_INIT_POINTER(t->next, rtnl_dereference(*tp));
+	RCU_INIT_POINTER(*tp, t);
 }
 
 static struct ip_tunnel * ipip_tunnel_locate(struct net *net,
@@ -301,7 +301,7 @@
 	struct ipip_net *ipn = net_generic(net, ipip_net_id);
 
 	if (dev == ipn->fb_tunnel_dev)
-		rcu_assign_pointer(ipn->tunnels_wc[0], NULL);
+		RCU_INIT_POINTER(ipn->tunnels_wc[0], NULL);
 	else
 		ipip_tunnel_unlink(ipn, netdev_priv(dev));
 	dev_put(dev);
@@ -791,7 +791,7 @@
 		return -ENOMEM;
 
 	dev_hold(dev);
-	rcu_assign_pointer(ipn->tunnels_wc[0], tunnel);
+	RCU_INIT_POINTER(ipn->tunnels_wc[0], tunnel);
 	return 0;
 }