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/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 3db78b6..8b6ebee 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -72,7 +72,7 @@
 	if (!s)
 		return -ENOENT;
 	if (s == sta) {
-		rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)],
+		RCU_INIT_POINTER(local->sta_hash[STA_HASH(sta->sta.addr)],
 				   s->hnext);
 		return 0;
 	}
@@ -82,7 +82,7 @@
 		s = rcu_dereference_protected(s->hnext,
 					lockdep_is_held(&local->sta_lock));
 	if (rcu_access_pointer(s->hnext)) {
-		rcu_assign_pointer(s->hnext, sta->hnext);
+		RCU_INIT_POINTER(s->hnext, sta->hnext);
 		return 0;
 	}
 
@@ -184,7 +184,7 @@
 			      struct sta_info *sta)
 {
 	sta->hnext = local->sta_hash[STA_HASH(sta->sta.addr)];
-	rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)], sta);
+	RCU_INIT_POINTER(local->sta_hash[STA_HASH(sta->sta.addr)], sta);
 }
 
 static void sta_unblock(struct work_struct *wk)
@@ -672,7 +672,7 @@
 	local->sta_generation++;
 
 	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
-		rcu_assign_pointer(sdata->u.vlan.sta, NULL);
+		RCU_INIT_POINTER(sdata->u.vlan.sta, NULL);
 
 	if (sta->uploaded) {
 		if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)