[MAC80211]: only honor IW_SCAN_THIS_ESSID in STA, IBSS, and AP modes

The previous IW_SCAN_THIS_ESSID patch left a hole allowing scan
requests on interfaces in inappropriate modes.
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/mac80211/ieee80211_ioctl.c

@@ -522,12 +522,6 @@ static int ieee80211_ioctl_siwscan(struct net_device *dev,
 	if (!netif_running(dev))
 		return -ENETDOWN;
 
-	if (wrqu->data.length == sizeof(struct iw_scan_req) &&
-	    wrqu->data.flags & IW_SCAN_THIS_ESSID) {
-		req = (struct iw_scan_req *)extra;
-		ssid = req->essid;
-		ssid_len = req->essid_len;
-	} else {
 	switch (sdata->type) {
 	case IEEE80211_IF_TYPE_STA:
 	case IEEE80211_IF_TYPE_IBSS:
@@ -545,6 +539,13 @@ static int ieee80211_ioctl_siwscan(struct net_device *dev,
 	default:
 		return -EOPNOTSUPP;
 	}
+
+	/* if SSID was specified explicitly then use that */
+	if (wrqu->data.length == sizeof(struct iw_scan_req) &&
+	    wrqu->data.flags & IW_SCAN_THIS_ESSID) {
+		req = (struct iw_scan_req *)extra;
+		ssid = req->essid;
+		ssid_len = req->essid_len;
 	}
 
 	return ieee80211_sta_req_scan(dev, ssid, ssid_len);