cgroup/systemd: fix systemdProperties setting CharDevice path problem

func systemdProperties will set CharDevice path like /dev/char/0:0,
but NVIDIA devices with major 195:* and minor 507:* can not be found in path /dev/char/x:x,
getNVIDIAEntryPath will fix this problem.

Signed-off-by: yangfeiyu20102011 <yangfeiyu20102011@163.com>

libcontainer/cgroups/devices/systemd.go

@@ -126,7 +126,7 @@ func systemdProperties(r *configs.Resources) ([]systemdDbus.Property, error) {
 			case devices.BlockDevice:
 				entry.Path = fmt.Sprintf("/dev/block/%d:%d", rule.Major, rule.Minor)
 			case devices.CharDevice:
-				entry.Path = fmt.Sprintf("/dev/char/%d:%d", rule.Major, rule.Minor)
+				entry.Path = getCharEntryPath(rule)
 			}
 			// systemd will issue a warning if the path we give here doesn't exist.
 			// Since all of this logic is best-effort anyway (we manually set these
@@ -239,3 +239,30 @@ func allowAllDevices() []systemdDbus.Property {
 		newProp("DeviceAllow", []deviceAllowEntry{}),
 	}
 }
+
+func getCharEntryPath(rule *devices.Rule) string {
+	switch rule.Major {
+	case 195:
+		// Special case for NVIDIA devices
+		switch rule.Minor {
+		case 254:
+			return "/dev/nvidia-modeset"
+		case 255:
+			return "/dev/nvidiactl"
+		default:
+			// nvidia0 /dev/nvidia0
+			// nvidia1 /dev/nvidia1
+			return fmt.Sprintf("/dev/nvidia%d", rule.Minor)
+		}
+	case 507:
+		// Special case for NVIDIA devices
+		switch rule.Minor {
+		case 0:
+			return "/dev/nvidia-uvm"
+		case 1:
+			return "/dev/nvidia-uvm-tools"
+		}
+	}
+
+	return fmt.Sprintf("/dev/char/%d:%d", rule.Major, rule.Minor)
+}

libcontainer/cgroups/devices/systemd_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"os"
 	"os/exec"
+	"reflect"
 	"strings"
 	"testing"
 
@@ -251,3 +252,93 @@ func newManager(t *testing.T, config *configs.Cgroup) (m cgroups.Manager) {
 
 	return m
 }
+
+func TestGetCharEntryPath(t *testing.T) {
+	tests := []struct {
+		name   string
+		rule   devices.Rule
+		expect string
+	}{
+		{
+			name: "normal char /dev/char/0:0",
+			rule: devices.Rule{
+				Type:  devices.CharDevice,
+				Major: 0,
+				Minor: 0,
+			},
+			expect: "/dev/char/0:0",
+		},
+		{
+			name: "normal char /dev/char/188:188",
+			rule: devices.Rule{
+				Type:  devices.CharDevice,
+				Major: 188,
+				Minor: 188,
+			},
+			expect: "/dev/char/188:188",
+		},
+		{
+			name: "nvidia /dev/nvidia0",
+			rule: devices.Rule{
+				Type:  devices.CharDevice,
+				Major: 195,
+				Minor: 0,
+			},
+			expect: "/dev/nvidia0",
+		},
+		{
+			name: "nvidia /dev/nvidia30",
+			rule: devices.Rule{
+				Type:  devices.CharDevice,
+				Major: 195,
+				Minor: 30,
+			},
+			expect: "/dev/nvidia30",
+		},
+		{
+			name: "nvidia /dev/nvidiactl",
+			rule: devices.Rule{
+				Type:  devices.CharDevice,
+				Major: 195,
+				Minor: 255,
+			},
+			expect: "/dev/nvidiactl",
+		},
+		{
+			name: "nvidia /dev/nvidia-modeset",
+			rule: devices.Rule{
+				Type:  devices.CharDevice,
+				Major: 195,
+				Minor: 254,
+			},
+			expect: "/dev/nvidia-modeset",
+		},
+		{
+			name: "nvidia /dev/nvidia-uvm",
+			rule: devices.Rule{
+				Type:  devices.CharDevice,
+				Major: 507,
+				Minor: 0,
+			},
+			expect: "/dev/nvidia-uvm",
+		},
+		{
+			name: "nvidia /dev/nvidia-uvm-tools",
+			rule: devices.Rule{
+				Type:  devices.CharDevice,
+				Major: 507,
+				Minor: 1,
+			},
+			expect: "/dev/nvidia-uvm-tools",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			path := getCharEntryPath(&test.rule)
+			if !reflect.DeepEqual(path, test.expect) {
+				t.Errorf("test %s error, expect %s but got %s", test.name, test.expect, path)
+			}
+		})
+	}
+}