plugins: avoid DeviceSpec and Mount copies

k8s/kubelet 1.34 updates its protocol buffer definitions and
triggers the following linter errors for pluginapi DeviceSpec and
Mount used in our code:

copylocks: range var mount copies lock: k8s.io/kubelet/pkg/apis/deviceplugin/v1beta1.Mount
contains google.golang.org/protobuf/runtime/protoimpl.MessageState contains sync.Mutex (govet

In most cases we loop a slice of pluginapi.DeviceSpec/Mount and taking
an instance of an element is copying. This can be avoided by accessing each
element from the slice directly using a range loop index instead.

Signed-off-by: Mikko Ylinen <mikko.ylinen@intel.com>

Author: mythi

cmd/gpu_plugin/gpu_plugin.go

@@ -572,7 +572,7 @@ func (dp *devicePlugin) isCompatibleDevice(name string) bool {
 	return true
 }
 
-func (dp *devicePlugin) devSpecForDrmFile(drmFile string) (devSpec pluginapi.DeviceSpec, devPath string, err error) {
+func (dp *devicePlugin) devPathForDrmFile(drmFile string) (devPath string, err error) {
 	if dp.controlDeviceReg.MatchString(drmFile) {
 		//Skipping possible drm control node
 		err = os.ErrInvalid
@@ -585,13 +585,6 @@ func (dp *devicePlugin) devSpecForDrmFile(drmFile string) (devSpec pluginapi.Dev
 		return
 	}
 
-	// even querying metrics requires device to be writable
-	devSpec = pluginapi.DeviceSpec{
-		HostPath:      devPath,
-		ContainerPath: devPath,
-		Permissions:   "rw",
-	}
-
 	return
 }
 
@@ -645,16 +638,20 @@ func (dp *devicePlugin) createDeviceSpecsFromDrmFiles(cardPath string) []plugina
 	drmFiles, _ := os.ReadDir(path.Join(cardPath, "device/drm"))
 
 	for _, drmFile := range drmFiles {
-		devSpec, devPath, devSpecErr := dp.devSpecForDrmFile(drmFile.Name())
-		if devSpecErr != nil {
+		devPath, devPathErr := dp.devPathForDrmFile(drmFile.Name())
+		if devPathErr != nil {
 			continue
 		}
 
 		klog.V(4).Infof("Adding %s to GPU %s", devPath, filepath.Base(cardPath))
 
-		specs = append(specs, devSpec)
+		// even querying metrics requires device to be writable
+		specs = append(specs, pluginapi.DeviceSpec{
+			HostPath:      devPath,
+			ContainerPath: devPath,
+			Permissions:   "rw",
+		})
 	}
-
 	return specs
 }
 
@@ -677,18 +674,18 @@ func (dp *devicePlugin) createMountsAndCDIDevices(cardPath, name string, devSpec
 
 	cedits := &spec.Devices[0].ContainerEdits
 
-	for _, dspec := range devSpecs {
+	for idx := range devSpecs {
 		cedits.DeviceNodes = append(cedits.DeviceNodes, &cdispec.DeviceNode{
-			HostPath:    dspec.HostPath,
-			Path:        dspec.ContainerPath,
-			Permissions: dspec.Permissions,
+			HostPath:    devSpecs[idx].HostPath,
+			Path:        devSpecs[idx].ContainerPath,
+			Permissions: devSpecs[idx].Permissions,
 		})
 	}
 
-	for _, mount := range mounts {
+	for idx := range mounts {
 		cedits.Mounts = append(cedits.Mounts, &cdispec.Mount{
-			HostPath:      mount.HostPath,
-			ContainerPath: mount.ContainerPath,
+			HostPath:      mounts[idx].HostPath,
+			ContainerPath: mounts[idx].ContainerPath,
 			Type:          "none",
 			Options:       []string{"bind", "ro"},
 		})

cmd/gpu_plugin/gpu_plugin_test.go

@@ -874,13 +874,13 @@ func TestBypath(t *testing.T) {
 			absPaths = append(absPaths, path.Join(byPath, link))
 		}
 
-		for _, mount := range mounts {
-			if !slices.Contains(absPaths, mount.ContainerPath) {
-				t.Errorf("%s: containerpath is incorrect: %s", td.desc, mount.ContainerPath)
+		for idx := range mounts {
+			if !slices.Contains(absPaths, mounts[idx].ContainerPath) {
+				t.Errorf("%s: containerpath is incorrect: %s", td.desc, mounts[idx].ContainerPath)
 			}
 
-			if !slices.Contains(absPaths, mount.HostPath) {
-				t.Errorf("%s: hostpath is incorrect: %s", td.desc, mount.HostPath)
+			if !slices.Contains(absPaths, mounts[idx].HostPath) {
+				t.Errorf("%s: hostpath is incorrect: %s", td.desc, mounts[idx].HostPath)
 			}
 		}
 	}

cmd/npu_plugin/npu_plugin.go

@@ -167,13 +167,14 @@ func (dp *devicePlugin) scan() (dpapi.DeviceTree, error) {
 		}
 
 		// even querying metrics requires device to be writable
-		devSpec := pluginapi.DeviceSpec{
+		devSpec := []pluginapi.DeviceSpec{{
 			HostPath:      devPath,
 			ContainerPath: devPath,
 			Permissions:   "rw",
+		},
 		}
 
-		deviceInfo := dpapi.NewDeviceInfo(pluginapi.Healthy, []pluginapi.DeviceSpec{devSpec}, nil, nil, nil, nil)
+		deviceInfo := dpapi.NewDeviceInfo(pluginapi.Healthy, devSpec, nil, nil, nil, nil)
 
 		for i := 0; i < dp.options.sharedDevNum; i++ {
 			devID := fmt.Sprintf("%s-%d", name, i)

pkg/deviceplugin/api.go

@@ -60,8 +60,8 @@ func NewDeviceInfo(state string, nodes []pluginapi.DeviceSpec, mounts []pluginap
 
 	devPaths := []string{}
 
-	for _, node := range nodes {
-		devPaths = append(devPaths, node.HostPath)
+	for idx := range nodes {
+		devPaths = append(devPaths, nodes[idx].HostPath)
 	}
 
 	topologyInfo, err := topology.GetTopologyInfo(devPaths)