Signed-off-by: Andrew Lunn <andrew@lunn.ch>

Index: madwifi-ng-r2568-20070710/net80211/ieee80211_beacon.c
===================================================================
--- madwifi-ng-r2568-20070710.orig/net80211/ieee80211_beacon.c	2007-10-20 20:52:09.000000000 +0200
+++ madwifi-ng-r2568-20070710/net80211/ieee80211_beacon.c	2007-10-20 20:52:31.000000000 +0200
@@ -305,13 +305,17 @@
 		 */
 		c = ieee80211_doth_findchan(vap, ic->ic_chanchange_chan);
 		if (c == NULL) {
+			/*
+			 * The channel we have been requested to change to
+			 * is not valid. Drop the channel switch annoucement
+			 * from the beacon and don't change channel.
+			 */
 			IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
-				"%s: find channel failure\n", __func__);
-			IEEE80211_UNLOCK_IRQ_EARLY(ic);
-			return 0;
+					  "%s: find channel failure\n", 
+					  __func__);
+		} else {
+			ic->ic_bsschan = c;
 		}
-		ic->ic_bsschan = c;
-
 		skb_pull(skb, sizeof(struct ieee80211_frame));
 		skb_trim(skb, 0);
 		frm = skb->data;
@@ -321,8 +325,10 @@
 		vap->iv_flags &= ~IEEE80211_F_CHANSWITCH;
 		ic->ic_flags &= ~IEEE80211_F_CHANSWITCH;
 
-		/* NB: only for the first VAP to get here */
-		if (ic->ic_curchan != c) {
+		/* NB: only for the first VAP to get here, and we have a valid
+		 *     new channel to change to.
+		 */
+		if (c && ic->ic_curchan != c) {
 			ic->ic_curchan = c;
 			ic->ic_set_channel(ic);
 		}