cfg80211: process pending events when unregistering net device

libertas currently calls cfg80211_disconnected() when it is being
brought down. This causes an event to be allocated, but since the
wdev is already removed from the rdev by the time that the event
processing work executes, the event is never processed or freed.
http://article.gmane.org/gmane.linux.kernel.wireless.general/95666

Fix this leak, and other possible situations, by processing the event
queue when a device is being unregistered. Thanks to Johannes Berg for
the suggestion.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Cc: stable@vger.kernel.org
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/core.c

@@ -952,6 +952,11 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 		 */
 		synchronize_rcu();
 		INIT_LIST_HEAD(&wdev->list);
+		/*
+		 * Ensure that all events have been processed and
+		 * freed.
+		 */
+		cfg80211_process_wdev_events(wdev);
 		break;
 	case NETDEV_PRE_UP:
 		if (!(wdev->wiphy->interface_modes & BIT(wdev->iftype)))

net/wireless/core.h

@@ -426,6 +426,7 @@ int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
 			  struct net_device *dev, enum nl80211_iftype ntype,
 			  u32 *flags, struct vif_params *params);
 void cfg80211_process_rdev_events(struct cfg80211_registered_device *rdev);
+void cfg80211_process_wdev_events(struct wireless_dev *wdev);
 
 int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
 				 struct wireless_dev *wdev,

net/wireless/util.c

@@ -735,7 +735,7 @@ void cfg80211_upload_connect_keys(struct wireless_dev *wdev)
 	wdev->connect_keys = NULL;
 }
 
-static void cfg80211_process_wdev_events(struct wireless_dev *wdev)
+void cfg80211_process_wdev_events(struct wireless_dev *wdev)
 {
 	struct cfg80211_event *ev;
 	unsigned long flags;