pkg/hostagent: Add HostAgent.onCloseMu

- Add `HostAgent.cleanUp()`
- use `HostAgent.onCloseMu` in `HostAgent.close()`

Signed-off-by: Norio Nomura <norio.nomura@gmail.com>

Author: norio-nomura

pkg/hostagent/hostagent.go

@@ -60,7 +60,8 @@ type HostAgent struct {
 	portForwarder     *portForwarder // legacy SSH port forwarder
 	grpcPortForwarder *portfwd.Forwarder
 
-	onClose []func() error // LIFO
+	onClose   []func() error // LIFO
+	onCloseMu sync.Mutex
 
 	driver   driver.Driver
 	signalCh chan os.Signal
@@ -502,7 +503,7 @@ func (a *HostAgent) startHostAgentRoutines(ctx context.Context) error {
 		}
 		logrus.Info(msg)
 	}
-	a.onClose = append(a.onClose, func() error {
+	a.cleanUp(func() error {
 		logrus.Debugf("shutting down the SSH master")
 		if exitMasterErr := ssh.ExitMaster(a.instSSHAddress, a.sshLocalPort, a.sshConfig); exitMasterErr != nil {
 			logrus.WithError(exitMasterErr).Warn("failed to exit SSH master")
@@ -531,7 +532,7 @@ sudo chown -R "${USER}" /run/host-services`
 		if err != nil {
 			errs = append(errs, err)
 		}
-		a.onClose = append(a.onClose, func() error {
+		a.cleanUp(func() error {
 			var unmountErrs []error
 			for _, m := range mounts {
 				if unmountErr := m.close(); unmountErr != nil {
@@ -542,7 +543,7 @@ sudo chown -R "${USER}" /run/host-services`
 		})
 	}
 	if len(a.instConfig.AdditionalDisks) > 0 {
-		a.onClose = append(a.onClose, func() error {
+		a.cleanUp(func() error {
 			var unlockErrs []error
 			for _, d := range a.instConfig.AdditionalDisks {
 				disk, inspectErr := store.InspectDisk(d.Name)
@@ -601,7 +602,7 @@ sudo chown -R "${USER}" /run/host-services`
 			errs = append(errs, err)
 		}
 	}
-	a.onClose = append(a.onClose, func() error {
+	a.cleanUp(func() error {
 		var rmErrs []error
 		for _, rule := range a.instConfig.CopyToHost {
 			if rule.DeleteOnStop {
@@ -616,7 +617,16 @@ sudo chown -R "${USER}" /run/host-services`
 	return errors.Join(errs...)
 }
 
+// cleanUp registers a cleanup function to be called when the host agent is stopped.
+func (a *HostAgent) cleanUp(fn func() error) {
+	a.onCloseMu.Lock()
+	defer a.onCloseMu.Unlock()
+	a.onClose = append(a.onClose, fn)
+}
+
 func (a *HostAgent) close() error {
+	a.onCloseMu.Lock()
+	defer a.onCloseMu.Unlock()
 	logrus.Infof("Shutting down the host agent")
 	var errs []error
 	for i := len(a.onClose) - 1; i >= 0; i-- {
@@ -645,7 +655,7 @@ func (a *HostAgent) watchGuestAgentEvents(ctx context.Context) {
 	localUnix := filepath.Join(a.instDir, filenames.GuestAgentSock)
 	remoteUnix := "/run/lima-guestagent.sock"
 
-	a.onClose = append(a.onClose, func() error {
+	a.cleanUp(func() error {
 		logrus.Debugf("Stop forwarding unix sockets")
 		var errs []error
 		for _, rule := range a.instConfig.PortForwards {