Fix the race condition in ifConfigurator (#2256)

ensureHNSNetwork may be called in parallel but the variable hnsNetwork
was not protected by lock, which could lead to data race. This patch
fixes it by initializing the variable when ifConfigurator is instantiated.

It also removes an unused variable.

Signed-off-by: Quan Tian <[email protected]>

pkg/agent/cniserver/interface_configuration_windows.go

@@ -45,10 +45,13 @@ const (
 type ifConfigurator struct {
 	hnsNetwork *hcsshim.HNSNetwork
 	epCache    *sync.Map
-	ifCache    *sync.Map
 }
 
 func newInterfaceConfigurator(ovsDatapathType ovsconfig.OVSDatapathType, isOvsHardwareOffloadEnabled bool) (*ifConfigurator, error) {
+	hnsNetwork, err := hcsshim.GetHNSNetworkByName(util.LocalHNSNetwork)
+	if err != nil {
+		return nil, err
+	}
 	eps, err := hcsshim.HNSListEndpointRequest()
 	if err != nil {
 		return nil, err
@@ -59,29 +62,15 @@ func newInterfaceConfigurator(ovsDatapathType ovsconfig.OVSDatapathType, isOvsHa
 		epCache.Store(hnsEP.Name, hnsEP)
 	}
 	return &ifConfigurator{
-		epCache: epCache,
+		hnsNetwork: hnsNetwork,
+		epCache:    epCache,
 	}, nil
-
 }
 
 func (ic *ifConfigurator) addEndpoint(ep *hcsshim.HNSEndpoint) {
 	ic.epCache.Store(ep.Name, ep)
 }
 
-// ensureHNSNetwork checks if the target HNSNetwork is created on the node or not. If the HNSNetwork does not exit,
-// return error.
-func (ic *ifConfigurator) ensureHNSNetwork() error {
-	if ic.hnsNetwork != nil {
-		return nil
-	}
-	hnsNetwork, err := hcsshim.GetHNSNetworkByName(util.LocalHNSNetwork)
-	if err != nil {
-		return err
-	}
-	ic.hnsNetwork = hnsNetwork
-	return nil
-}
-
 func (ic *ifConfigurator) getEndpoint(name string) (*hcsshim.HNSEndpoint, bool) {
 	value, ok := ic.epCache.Load(name)
 	if !ok {
@@ -162,10 +151,6 @@ func (ic *ifConfigurator) configureContainerLink(
 
 // createContainerLink creates HNSEndpoint using the IP configuration in the IPAM result.
 func (ic *ifConfigurator) createContainerLink(endpointName string, result *current.Result, containerID, podName, podNamespace string) (hostLink *hcsshim.HNSEndpoint, err error) {
-	// Create a new Endpoint if not found.
-	if err := ic.ensureHNSNetwork(); err != nil {
-		return nil, err
-	}
 	containerIP, err := findContainerIPConfig(result.IPs)
 	if err != nil {
 		return nil, err