fix empty AllocateFrom handling

Author: killwing

crishim/pkg/device/devicemanager.go

@@ -108,7 +108,7 @@ func (d *DevicesManager) AllocateDevices(pod *types.PodInfo, cont *types.Contain
 	for i, device := range d.Devices {
 		if d.Operational[i] {
 			alloc, err := device.Allocate(pod, cont)
-			if err == nil {
+			if err == nil && alloc != nil {
 				// only set envs for now
 				for k, v := range alloc.Envs {
 					resp.Envs[k] = v

crishim/pkg/kubecri/docker_container.go

@@ -35,9 +35,13 @@ type dockerExtService struct {
 }
 
 func (d *dockerExtService) modifyContainerConfig(pod *types.PodInfo, cont *types.ContainerInfo, config *runtimeapi.ContainerConfig) error {
+	numAllocateFrom := len(cont.AllocateFrom) // may be zero from old scheduler
+	if numAllocateFrom == 0 {
+		return nil
+	}
+
 	glog.V(3).Infof("original container config: %s", config.String())
 
-	numAllocateFrom := len(cont.AllocateFrom) // may be zero from old scheduler
 	var visDev *string
 	// https://github.com/NVIDIA/nvidia-container-runtime#nvidia_visible_devices
 	for _, v := range config.Envs {