wl1271: Fix scan failure detection

In scan_complete_work, because the mutex is released before accessing the
scan->failed flag, it is possible for unfounded hardware recovery rounds
to be executed.

Fix this.
Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>

drivers/net/wireless/wl12xx/wl1271_main.c

@@ -1056,6 +1056,7 @@ static void __wl1271_op_remove_interface(struct wl1271 *wl)
 		wl->scan.state = WL1271_SCAN_STATE_IDLE;
 		kfree(wl->scan.scanned_ch);
 		wl->scan.scanned_ch = NULL;
+		wl->scan.req = NULL;
 		ieee80211_scan_completed(wl->hw, true);
 	}
 
@@ -1676,6 +1677,16 @@ static int wl1271_op_hw_scan(struct ieee80211_hw *hw,
 
 	mutex_lock(&wl->mutex);
 
+	if (wl->state == WL1271_STATE_OFF) {
+		/*
+		 * We cannot return -EBUSY here because cfg80211 will expect
+		 * a call to ieee80211_scan_completed if we do - in this case
+		 * there won't be any call.
+		 */
+		ret = -EAGAIN;
+		goto out;
+	}
+
 	ret = wl1271_ps_elp_wakeup(wl, false);
 	if (ret < 0)
 		goto out;

drivers/net/wireless/wl12xx/wl1271_scan.c

@@ -48,14 +48,15 @@ void wl1271_scan_complete_work(struct work_struct *work)
 	wl->scan.state = WL1271_SCAN_STATE_IDLE;
 	kfree(wl->scan.scanned_ch);
 	wl->scan.scanned_ch = NULL;
-	mutex_unlock(&wl->mutex);
-
+	wl->scan.req = NULL;
 	ieee80211_scan_completed(wl->hw, false);
 
 	if (wl->scan.failed) {
 		wl1271_info("Scan completed due to error.");
 		ieee80211_queue_work(wl->hw, &wl->recovery_work);
 	}
+	mutex_unlock(&wl->mutex);
+
 }