mac80211: abort scan_work immediately when the device goes down

As long as no delay is required b/w channel change, scan work
is proceeding without scheduling a new work. In such case, we
can not abort scan work when the card was unplugged. This patch
completes the scanning immediately whenever the device goes down.
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Rajkumar Manoharan <rmanoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/iface.c

@@ -384,11 +384,11 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
 	int i;
 	enum nl80211_channel_type orig_ct;
 
+	clear_bit(SDATA_STATE_RUNNING, &sdata->state);
+
 	if (local->scan_sdata == sdata)
 		ieee80211_scan_cancel(local);
 
-	clear_bit(SDATA_STATE_RUNNING, &sdata->state);
-
 	/*
 	 * Stop TX on this interface first.
 	 */

net/mac80211/scan.c

@@ -719,6 +719,11 @@ void ieee80211_scan_work(struct work_struct *work)
 	 * without scheduling a new work
 	 */
 	do {
+		if (!ieee80211_sdata_running(sdata)) {
+			aborted = true;
+			goto out_complete;
+		}
+
 		switch (local->next_scan_state) {
 		case SCAN_DECISION:
 			/* if no more bands/channels left, complete scan */