@@ -6,6 +6,7 @@ import (

 	"fmt"

 	"sync"

+	"github.com/docker/docker/pkg/locker"

 	"github.com/docker/docker/pkg/plugins"

 	"github.com/docker/docker/volume"

 )

@@ -13,7 +14,7 @@ import (

 // currently created by hand. generation tool would generate this like:

 // $ extpoint-gen Driver > volume/extpoint.go

-var drivers = &driverExtpoint{extensions: make(map[string]volume.Driver)}

+var drivers = &driverExtpoint{extensions: make(map[string]volume.Driver), driverLock: &locker.Locker{}}

 const extName = "VolumeDriver"

@@ -49,16 +50,19 @@ type volumeDriver interface {

 type driverExtpoint struct {

 	extensions map[string]volume.Driver

 	sync.Mutex

+	driverLock *locker.Locker

 }

 // Register associates the given driver to the given name, checking if

 // the name is already associated

 func Register(extension volume.Driver, name string) bool {

-	drivers.Lock()

-	defer drivers.Unlock()

 	if name == "" {

 		return false

 	}

+

+	drivers.Lock()

+	defer drivers.Unlock()

+

 	_, exists := drivers.extensions[name]

 	if exists {

 		return false

@@ -71,6 +75,7 @@ func Register(extension volume.Driver, name string) bool {

 func Unregister(name string) bool {

 	drivers.Lock()

 	defer drivers.Unlock()

+

 	_, exists := drivers.extensions[name]

 	if !exists {

 		return false

@@ -83,12 +88,16 @@ func Unregister(name string) bool {

 // driver with the given name has not been registered it checks if

 // there is a VolumeDriver plugin available with the given name.

 func Lookup(name string) (volume.Driver, error) {

+	drivers.driverLock.Lock(name)

+	defer drivers.driverLock.Unlock(name)

+

 	drivers.Lock()

 	ext, ok := drivers.extensions[name]

 	drivers.Unlock()

 	if ok {

 		return ext, nil

 	}

+

 	pl, err := plugins.Get(name, extName)

 	if err != nil {

 		return nil, fmt.Errorf("Error looking up volume plugin %s: %v", name, err)

@@ -118,9 +127,11 @@ func GetDriver(name string) (volume.Driver, error) {

 // If no driver is registered, empty string list will be returned.

 func GetDriverList() []string {

 	var driverList []string

+	drivers.Lock()

 	for driverName := range drivers.extensions {

 		driverList = append(driverList, driverName)

 	}

+	drivers.Unlock()

 	return driverList

 }

@@ -144,6 +155,7 @@ func GetAllDrivers() ([]volume.Driver, error) {

 		if ok {

 			continue

 		}

+

 		ext = NewVolumeDriver(p.Name, p.Client)

 		drivers.extensions[p.Name] = ext

 		ds = append(ds, ext)