fix issue with survival of nebula service from previous testrun

udp/udp_linux.go

@@ -22,10 +22,11 @@ import (
 //TODO: make it support reload as best you can!
 
 type StdConn struct {
-	sysFd int
-	isV4  bool
-	l     *logrus.Logger
-	batch int
+	sysFd  int
+	closed bool
+	isV4   bool
+	l      *logrus.Logger
+	batch  int
 }
 
 func maybeIPV4(ip net.IP) (net.IP, bool) {
@@ -142,6 +143,11 @@ func (u *StdConn) ListenOut(r EncReader, lhf LightHouseHandlerFunc, cache *firew
 			return
 		}
 
+		if u.closed {
+			u.l.WithError(err).Debug("flag for closing connection is set, exiting read loop")
+			return
+		}
+
 		//metric.Update(int64(n))
 		for i := 0; i < n; i++ {
 			if u.isV4 {
@@ -315,6 +321,10 @@ func (u *StdConn) getMemInfo(meminfo *[unix.SK_MEMINFO_VARS]uint32) error {
 
 func (u *StdConn) Close() error {
 	//TODO: this will not interrupt the read loop
+	if u.closed {
+		return nil
+	}
+	u.closed = true
 	return syscall.Close(u.sysFd)
 }