rdma: support rdma link add/del functionality

Signed-off-by: Wei Fu <fuweid89@gmail.com>

nl/rdma_link_linux.go

@@ -11,6 +11,8 @@ const (
 const (
 	RDMA_NLDEV_CMD_GET     = 1
 	RDMA_NLDEV_CMD_SET     = 2
+	RDMA_NLDEV_CMD_NEWLINK = 3
+	RDMA_NLDEV_CMD_DELLINK = 4
 	RDMA_NLDEV_CMD_SYS_GET = 6
 	RDMA_NLDEV_CMD_SYS_SET = 7
 )
@@ -30,6 +32,8 @@ const (
 	RDMA_NLDEV_ATTR_PORT_STATE      = 12
 	RDMA_NLDEV_ATTR_PORT_PHYS_STATE = 13
 	RDMA_NLDEV_ATTR_DEV_NODE_TYPE   = 14
+	RDMA_NLDEV_ATTR_NDEV_NAME       = 51
+	RDMA_NLDEV_ATTR_LINK_TYPE       = 65
 	RDMA_NLDEV_SYS_ATTR_NETNS_MODE  = 66
 	RDMA_NLDEV_NET_NS_FD            = 68
 )

rdma_link_linux.go

@@ -278,3 +278,54 @@ func (h *Handle) RdmaLinkSetNsFd(link *RdmaLink, fd uint32) error {
 
 	return execRdmaSetLink(req)
 }
+
+// RdmaLinkDel deletes an rdma link
+//
+// Similar to: rdma link delete NAME
+// REF: https://man7.org/linux/man-pages/man8/rdma-link.8.html
+func RdmaLinkDel(name string) error {
+	return pkgHandle.RdmaLinkDel(name)
+}
+
+// RdmaLinkDel deletes an rdma link.
+func (h *Handle) RdmaLinkDel(name string) error {
+	link, err := h.RdmaLinkByName(name)
+	if err != nil {
+		return err
+	}
+
+	proto := getProtoField(nl.RDMA_NL_NLDEV, nl.RDMA_NLDEV_CMD_DELLINK)
+	req := h.newNetlinkRequest(proto, unix.NLM_F_ACK)
+
+	b := make([]byte, 4)
+	native.PutUint32(b, link.Attrs.Index)
+	req.AddData(nl.NewRtAttr(nl.RDMA_NLDEV_ATTR_DEV_INDEX, b))
+
+	_, err = req.Execute(unix.NETLINK_RDMA, 0)
+	return err
+}
+
+// RdmaLinkAdd adds an rdma link for the specified type to the network device.
+// Similar to: rdma link add NAME type TYPE netdev NETDEV
+//	NAME - specifies the new name of the rdma link to add
+//	TYPE - specifies which rdma type to use.  Link types:
+//		rxe - Soft RoCE driver
+//		siw - Soft iWARP driver
+//	NETDEV - specifies the network device to which the link is bound
+//
+// REF: https://man7.org/linux/man-pages/man8/rdma-link.8.html
+func RdmaLinkAdd(linkName, linkType, netdev string) error {
+	return pkgHandle.RdmaLinkAdd(linkName, linkType, netdev)
+}
+
+// RdmaLinkAdd adds an rdma link for the specified type to the network device.
+func (h *Handle) RdmaLinkAdd(linkName string, linkType string, netdev string) error {
+	proto := getProtoField(nl.RDMA_NL_NLDEV, nl.RDMA_NLDEV_CMD_NEWLINK)
+	req := h.newNetlinkRequest(proto, unix.NLM_F_ACK)
+
+	req.AddData(nl.NewRtAttr(nl.RDMA_NLDEV_ATTR_DEV_NAME, nl.ZeroTerminated(linkName)))
+	req.AddData(nl.NewRtAttr(nl.RDMA_NLDEV_ATTR_LINK_TYPE, nl.ZeroTerminated(linkType)))
+	req.AddData(nl.NewRtAttr(nl.RDMA_NLDEV_ATTR_NDEV_NAME, nl.ZeroTerminated(netdev)))
+	_, err := req.Execute(unix.NETLINK_RDMA, 0)
+	return err
+}

rdma_link_test.go

@@ -3,10 +3,11 @@
 package netlink
 
 import (
-	"github.com/vishvananda/netns"
 	"io/ioutil"
 	"strings"
 	"testing"
+
+	"github.com/vishvananda/netns"
 )
 
 func setupRdmaKModule(t *testing.T, name string) {
@@ -165,3 +166,42 @@ func TestRdmaLinkList(t *testing.T) {
 		t.Logf("%d: %s", link.Attrs.Index, link.Attrs.Name)
 	}
 }
+
+func TestRdmaLinkAddAndDel(t *testing.T) {
+	// related commit is https://github.com/torvalds/linux/commit/3856ec4b93c9463d36ee39098dde1fbbd29ec6dd.
+	minKernelRequired(t, 5, 1)
+	setupRdmaKModule(t, "rdma_rxe")
+
+	checkPresence := func(name string, exist bool) {
+		links, err := RdmaLinkList()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		found := false
+		for _, link := range links {
+			if link.Attrs.Name == name {
+				found = true
+				break
+			}
+		}
+
+		if found != exist {
+			t.Fatalf("expected rdma link %s presence=%v, but got presence=%v", name, exist, found)
+		}
+	}
+
+	linkName := t.Name()
+
+	if err := RdmaLinkAdd(linkName, "rxe", "lo"); err != nil {
+		t.Fatal(err)
+	}
+
+	checkPresence(linkName, true)
+
+	if err := RdmaLinkDel(linkName); err != nil {
+		t.Fatal(err)
+	}
+
+	checkPresence(linkName, false)
+}