check Linux bridge status before remove it (Cherry-picked from commit a33f0e7)

ustcweizhou · ustcweizhou · commit c2fc6e69b5ea · 2013-11-08T09:00:12.000+01:00
diff --git a/plugins/hypervisors/kvm/src/com/cloud/hypervisor/kvm/resource/BridgeVifDriver.java b/plugins/hypervisors/kvm/src/com/cloud/hypervisor/kvm/resource/BridgeVifDriver.java
@@ -205,7 +205,11 @@ private void createVnet(String vnetId, String pif, String brName, String protoco
 
     private void deleteVnetBr(String brName) {
         synchronized (_vnetBridgeMonitor) {
-            String cmdout = Script.runSimpleBashScript("ls /sys/class/net/" + brName + "/brif | tr '\n' ' '");
+            String cmdout = Script.runSimpleBashScript("ls /sys/class/net/" + brName);
+            if (cmdout == null)
+                // Bridge does not exist
+                return;
+            cmdout = Script.runSimpleBashScript("ls /sys/class/net/" + brName + "/brif | tr '\n' ' '");
             if (cmdout != null && cmdout.contains("vnet")) {
                 // Active VM remains on that bridge
                 return;
