mac80211: deauth before flushing STA information

Even after commit "mac80211: deauth when interface is marked down"
(e327b847 on Linus tree), userspace still isn't notified when interface
goes down. There isn't a problem with this commit, but because of other
code changes it doesn't work on kernels >= 2.6.28 (works if same/similar
change applied on 2.6.27 for example).

The issue is as follows: after commit "mac80211: restructure disassoc/deauth
flows" in 2.6.28, the call to ieee80211_sta_deauthenticate added by
commit e327b847 will not work: because we do sta_info_flush(local, sdata)
inside ieee80211_stop (iface.c), all stations in interface are cleared, so
when calling ieee80211_sta_deauthenticate->ieee80211_set_disassoc (mlme.c),
inside ieee80211_set_disassoc we have this in the beginning:

         sta = sta_info_get(local, ifsta->bssid);
         if (!sta) {

The !sta check triggers, thus the function returns early and
ieee80211_sta_send_apinfo(sdata, ifsta) later isn't called, so
wpa_supplicant/userspace isn't notified with SIOCGIWAP.

This commit moves deauthentication to before flushing STA info
(sta_info_flush), thus the above can't happen and userspace is really
notified when interface goes down.

Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/iface.c

@@ -369,6 +369,18 @@ static int ieee80211_stop(struct net_device *dev)
 
 	rcu_read_unlock();
 
+	/*
+	 * Announce that we are leaving the network, in case we are a
+	 * station interface type. This must be done before removing
+	 * all stations associated with sta_info_flush, otherwise STA
+	 * information will be gone and no announce being done.
+	 */
+	if (sdata->vif.type == NL80211_IFTYPE_STATION) {
+		if (sdata->u.mgd.state != IEEE80211_STA_MLME_DISABLED)
+			ieee80211_sta_deauthenticate(sdata,
+				WLAN_REASON_DEAUTH_LEAVING);
+	}
+
 	/*
 	 * Remove all stations associated with this interface.
 	 *
@@ -454,10 +466,6 @@ static int ieee80211_stop(struct net_device *dev)
 		netif_addr_unlock_bh(local->mdev);
 		break;
 	case NL80211_IFTYPE_STATION:
-		/* Announce that we are leaving the network. */
-		if (sdata->u.mgd.state != IEEE80211_STA_MLME_DISABLED)
-			ieee80211_sta_deauthenticate(sdata,
-						WLAN_REASON_DEAUTH_LEAVING);
 		memset(sdata->u.mgd.bssid, 0, ETH_ALEN);
 		del_timer_sync(&sdata->u.mgd.chswitch_timer);
 		del_timer_sync(&sdata->u.mgd.timer);