expose lock release error from iptables util

pkg/util/iptables/BUILD

@@ -24,6 +24,7 @@ go_library(
         "//vendor/github.com/godbus/dbus:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
         "//vendor/golang.org/x/sys/unix:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/errors:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",
     ],

pkg/util/iptables/iptables.go

@@ -338,7 +338,7 @@ func (runner *runner) RestoreAll(data []byte, flush FlushFlag, counters RestoreC
 }
 
 type iptablesLocker interface {
-	Close()
+	Close() error
 }
 
 // restoreInternal is the shared part of Restore/RestoreAll
@@ -361,7 +361,11 @@ func (runner *runner) restoreInternal(args []string, data []byte, flush FlushFla
 		if err != nil {
 			return err
 		}
-		defer locker.Close()
+		defer func(locker iptablesLocker) {
+			if err := locker.Close(); err != nil {
+				glog.Errorf("Failed to close iptables locks: %v", err)
+			}
+		}(locker)
 	}
 
 	// run the command and return the output or an error including the output and error

pkg/util/iptables/iptables_linux.go

@@ -25,6 +25,7 @@ import (
 	"time"
 
 	"golang.org/x/sys/unix"
+	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 	"k8s.io/apimachinery/pkg/util/wait"
 )
 
@@ -33,13 +34,19 @@ type locker struct {
 	lock14 *net.UnixListener
 }
 
-func (l *locker) Close() {
+func (l *locker) Close() error {
+	errList := []error{}
 	if l.lock16 != nil {
-		l.lock16.Close()
+		if err := l.lock16.Close(); err != nil {
+			errList = append(errList, err)
+		}
 	}
 	if l.lock14 != nil {
-		l.lock14.Close()
+		if err := l.lock14.Close(); err != nil {
+			errList = append(errList, err)
+		}
 	}
+	return utilerrors.NewAggregate(errList)
 }
 
 func grabIptablesLocks(lockfilePath string) (iptablesLocker, error) {