Add devlink command by to get specific device name

Add a command to get information about a specific devlink device
referenced by device name (bus, device).

Remove unused setupDevlinkKModule().

Signed-off-by: Parav Pandit <parav@mellanox.com>

devlink_linux.go

@@ -165,3 +165,68 @@ func (h *Handle) DevLinkGetDeviceList() ([]*DevlinkDevice, error) {
 func DevLinkGetDeviceList() ([]*DevlinkDevice, error) {
 	return pkgHandle.DevLinkGetDeviceList()
 }
+
+func parseDevlinkDevice(msgs [][]byte) (*DevlinkDevice, error) {
+	m := msgs[0]
+	attrs, err := nl.ParseRouteAttr(m[nl.SizeofGenlmsg:])
+	if err != nil {
+		return nil, err
+	}
+	dev := &DevlinkDevice{}
+	if err = dev.parseAttributes(attrs); err != nil {
+		return nil, err
+	}
+	return dev, nil
+}
+
+func (h *Handle) createCmdReq(cmd uint8, bus string, device string) (*GenlFamily, *nl.NetlinkRequest, error) {
+	f, err := h.GenlFamilyGet(nl.GENL_DEVLINK_NAME)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	msg := &nl.Genlmsg{
+		Command: cmd,
+		Version: nl.GENL_DEVLINK_VERSION,
+	}
+	req := h.newNetlinkRequest(int(f.ID),
+		unix.NLM_F_REQUEST|unix.NLM_F_ACK)
+	req.AddData(msg)
+
+	b := make([]byte, len(bus)+1)
+	copy(b, bus)
+	data := nl.NewRtAttr(nl.DEVLINK_ATTR_BUS_NAME, b)
+	req.AddData(data)
+
+	b = make([]byte, len(device)+1)
+	copy(b, device)
+	data = nl.NewRtAttr(nl.DEVLINK_ATTR_DEV_NAME, b)
+	req.AddData(data)
+
+	return f, req, nil
+}
+
+// DevlinkGetDeviceByName provides a pointer to devlink device and nil error,
+// otherwise returns an error code.
+func (h *Handle) DevLinkGetDeviceByName(Bus string, Device string) (*DevlinkDevice, error) {
+	f, req, err := h.createCmdReq(nl.DEVLINK_CMD_GET, Bus, Device)
+	if err != nil {
+		return nil, err
+	}
+
+	respmsg, err := req.Execute(unix.NETLINK_GENERIC, 0)
+	if err != nil {
+		return nil, err
+	}
+	dev, err := parseDevlinkDevice(respmsg)
+	if err == nil {
+		h.getEswitchAttrs(f, dev)
+	}
+	return dev, err
+}
+
+// DevlinkGetDeviceByName provides a pointer to devlink device and nil error,
+// otherwise returns an error code.
+func DevLinkGetDeviceByName(Bus string, Device string) (*DevlinkDevice, error) {
+	return pkgHandle.DevLinkGetDeviceByName(Bus, Device)
+}

devlink_test.go

@@ -3,27 +3,9 @@
 package netlink
 
 import (
-	"io/ioutil"
-	"strings"
 	"testing"
 )
 
-func setupDevlinkKModule(t *testing.T, name string) {
-	skipUnlessRoot(t)
-	file, err := ioutil.ReadFile("/proc/modules")
-	if err != nil {
-		t.Fatal("Failed to open /proc/modules", err)
-	}
-	for _, line := range strings.Split(string(file), "\n") {
-		n := strings.Split(line, " ")[0]
-		if n == name {
-			return
-		}
-
-	}
-	t.Skipf("Test requires kmodule %q.", name)
-}
-
 func TestDevLinkGetDeviceList(t *testing.T) {
 	minKernelRequired(t, 4, 12)
 	setUpNetlinkTestWithKModule(t, "devlink")
@@ -32,3 +14,12 @@ func TestDevLinkGetDeviceList(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestDevLinkGetDeviceByName(t *testing.T) {
+	minKernelRequired(t, 4, 12)
+	setUpNetlinkTestWithKModule(t, "devlink")
+	_, err := DevLinkGetDeviceByName("foo", "bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+}