net: reintroduce missing rcu_assign_pointer() calls

commit a9b3cd7f32 (rcu: convert uses of rcu_assign_pointer(x, NULL) to
RCU_INIT_POINTER) did a lot of incorrect changes, since it did a
complete conversion of rcu_assign_pointer(x, y) to RCU_INIT_POINTER(x,
y).

We miss needed barriers, even on x86, when y is not NULL.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 65f01dc..e41c40f 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -258,7 +258,7 @@
 		ip_mc_up(in_dev);
 
 	/* we can receive as soon as ip_ptr is set -- do this last */
-	RCU_INIT_POINTER(dev->ip_ptr, in_dev);
+	rcu_assign_pointer(dev->ip_ptr, in_dev);
 out:
 	return in_dev;
 out_kfree: