Revert "Revert "Don't take the proxy mutex in the traffic path""

pkg/proxy/userspace/proxier.go

@@ -41,6 +41,7 @@ type portal struct {
 }
 
 type serviceInfo struct {
+	isAliveAtomic       int32 // Only access this with atomic ops
 	portal              portal
 	protocol            api.Protocol
 	proxyPort           int
@@ -55,6 +56,18 @@ type serviceInfo struct {
 	externalIPs []string
 }
 
+func (info *serviceInfo) setAlive(b bool) {
+	var i int32
+	if b {
+		i = 1
+	}
+	atomic.StoreInt32(&info.isAliveAtomic, i)
+}
+
+func (info *serviceInfo) isAlive() bool {
+	return atomic.LoadInt32(&info.isAliveAtomic) != 0
+}
+
 func logTimeout(err error) bool {
 	if e, ok := err.(net.Error); ok {
 		if e.Timeout() {
@@ -256,6 +269,7 @@ func (proxier *Proxier) stopProxy(service proxy.ServicePortName, info *serviceIn
 // This assumes proxier.mu is locked.
 func (proxier *Proxier) stopProxyInternal(service proxy.ServicePortName, info *serviceInfo) error {
 	delete(proxier.serviceMap, service)
+	info.setAlive(false)
 	err := info.socket.Close()
 	port := info.socket.ListenPort()
 	proxier.proxyPorts.Release(port)
@@ -294,6 +308,7 @@ func (proxier *Proxier) addServiceOnPort(service proxy.ServicePortName, protocol
 		return nil, err
 	}
 	si := &serviceInfo{
+		isAliveAtomic:       1,
 		proxyPort:           portNum,
 		protocol:            protocol,
 		socket:              sock,