mac80211: free ifsta->extra_ie and clear IEEE80211_STA_PRIVACY_INVOKED

I'm not sure if this is best choice, someone might have better
solutions. But this patch fixed the connection problem when switching
from a WPA enabled AP (using wpa_supplicant) to an open AP (using
iwconfig). The root cause is when we connect to a WPA enabled AP,
wpa_supplicant sets the ifsta->extra_ie thru SIOCSIWGENIE. But if we
stop wpa_supplicant and connect to an open AP with iwconfig, there is
no way to clear the extra_ie so that mac80211 keeps connecting with that.

Someone could argue wpa_supplicant should clear the extra_ie during
its shutdown. But mac80211 should also handle the unexpected shutdown
case (ie. killall -9 wpa_supplicant).

On Wed, 2007-11-21 at 16:19 +0100, Johannes Berg wrote:
> Yeah. Can you amend the patch to also clear the
> IEEE80211_STA_PRIVACY_INVOKED flag?
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/ieee80211.c

@@ -334,6 +334,11 @@ static int ieee80211_stop(struct net_device *dev)
 			cancel_delayed_work(&local->scan_work);
 		}
 		flush_workqueue(local->hw.workqueue);
+
+		sdata->u.sta.flags &= ~IEEE80211_STA_PRIVACY_INVOKED;
+		kfree(sdata->u.sta.extra_ie);
+		sdata->u.sta.extra_ie = NULL;
+		sdata->u.sta.extra_ie_len = 0;
 		/* fall through */
 	default:
 		conf.if_id = dev->ifindex;