cfg80211: stop sched scan only when needed

cfg80211_leave stops sched scan when any station vif
is leaving. Add an explicit check and call it only
when the relevant vif (the one we scan on) is leaving.
Signed-off-by: Barak Bercovitz <barak@wizery.com>
[Eliad - changed the commit message a bit]
Signed-off-by: Eliad Peller <eliad@wizery.com>
[Johannes - add ASSERT_RTNL since that protects the pointer]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/core.c

@@ -756,13 +756,16 @@ void cfg80211_leave(struct cfg80211_registered_device *rdev,
 {
 	struct net_device *dev = wdev->netdev;
 
+	ASSERT_RTNL();
+
 	switch (wdev->iftype) {
 	case NL80211_IFTYPE_ADHOC:
 		cfg80211_leave_ibss(rdev, dev, true);
 		break;
 	case NL80211_IFTYPE_P2P_CLIENT:
 	case NL80211_IFTYPE_STATION:
-		__cfg80211_stop_sched_scan(rdev, false);
+		if (rdev->sched_scan_req && dev == rdev->sched_scan_req->dev)
+			__cfg80211_stop_sched_scan(rdev, false);
 
 		wdev_lock(wdev);
 #ifdef CONFIG_CFG80211_WEXT