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/mac80211/cfg.c b/net/mac80211/cfg.c
index 850bb96..e60df48 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -616,7 +616,7 @@
 
 	sdata->vif.bss_conf.dtim_period = new->dtim_period;
 
-	RCU_INIT_POINTER(sdata->u.ap.beacon, new);
+	rcu_assign_pointer(sdata->u.ap.beacon, new);
 
 	synchronize_rcu();
 
@@ -1033,7 +1033,7 @@
 				return -EBUSY;
 			}
 
-			RCU_INIT_POINTER(vlansdata->u.vlan.sta, sta);
+			rcu_assign_pointer(vlansdata->u.vlan.sta, sta);
 		}
 
 		sta->sdata = vlansdata;