mac80211: move some RCU locking into an if branch

The if itself doesn't need to be protected, so move in the RCU
locking to avoid doing anything at all when the condition isn't
true.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/mlme.c

@@ -2612,13 +2612,12 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 				      mesh_peer_accepts_plinks(elems));
 	}
 
-	rcu_read_lock();
-
 	if (sdata->vif.type == IEEE80211_IF_TYPE_IBSS && elems->supp_rates &&
 	    memcmp(mgmt->bssid, sdata->u.sta.bssid, ETH_ALEN) == 0) {
-
 		supp_rates = ieee80211_sta_get_rates(local, elems, band);
 
+		rcu_read_lock();
+
 		sta = sta_info_get(local, mgmt->sa);
 		if (sta) {
 			u64 prev_rates;
@@ -2642,9 +2641,9 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 			ieee80211_ibss_add_sta(sdata, NULL, mgmt->bssid,
 					       mgmt->sa, supp_rates);
 		}
-	}
 
-	rcu_read_unlock();
+		rcu_read_unlock();
+	}
 
 	if (elems->ds_params && elems->ds_params_len == 1)
 		freq = ieee80211_channel_to_frequency(elems->ds_params[0]);