Back-port of the following upstream commit...

commit ad935687dbe7307f5abd9e3f610a965a287324a9
Author: Kalle Valo <kalle.valo@iki.fi>
Date:   Sun Apr 19 08:47:19 2009 +0300

    mac80211: fix beacon loss detection after scan
    
    Currently beacon loss detection triggers after a scan. A probe request
    is sent and a message like this is printed to the log:
    
    wlan0: beacon loss from AP 00:12:17:e7:98:de - sending probe request
    
    But in fact there is no beacon loss, the beacons are just not received
    because of the ongoing scan. Fix it by updating last_beacon after
    the scan has finished.
    
    Reported-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
    Signed-off-by: Kalle Valo <kalle.valo@iki.fi>
    Acked-by: Johannes Berg <johannes@sipsolutions.net>
    Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff -up linux-2.6.29.noarch/net/mac80211/mlme.c.orig linux-2.6.29.noarch/net/mac80211/mlme.c
--- linux-2.6.29.noarch/net/mac80211/mlme.c.orig	2009-04-22 10:28:59.000000000 -0400
+++ linux-2.6.29.noarch/net/mac80211/mlme.c	2009-04-22 10:36:24.000000000 -0400
@@ -2364,9 +2364,30 @@ static void ieee80211_sta_work(struct wo
 
 static void ieee80211_restart_sta_timer(struct ieee80211_sub_if_data *sdata)
 {
-	if (sdata->vif.type == NL80211_IFTYPE_STATION)
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta;
+
+	rcu_read_lock();
+
+	sta = sta_info_get(local, sdata->u.sta.bssid);
+	if (!sta) {
+		rcu_read_unlock();
+		return;
+	}
+
+ 	if (sdata->vif.type == NL80211_IFTYPE_STATION) {
+ 		/*
+ 		 * Need to update last_rx to avoid beacon loss
+ 		 * test to trigger.
+ 		 */
+ 		sta->last_rx = jiffies;
+ 
+ 
 		queue_work(sdata->local->hw.workqueue,
 			   &sdata->u.sta.work);
+	}
+
+	rcu_read_unlock();
 }
 
 /* interface setup */