bump runc@b263a43430ac6996a4302b891688544225197294

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/apply_raw.go

@@ -9,7 +9,6 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"strconv"
 	"sync"
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
@@ -33,7 +32,6 @@ var (
 		&FreezerGroup{},
 		&NameGroup{GroupName: "name=systemd", Join: true},
 	}
-	CgroupProcesses  = "cgroup.procs"
 	HugePageSizes, _ = cgroups.GetHugePageSize()
 )
 
@@ -106,6 +104,8 @@ func (m *Manager) Apply(pid int) (err error) {
 	if m.Cgroups == nil {
 		return nil
 	}
+	m.mu.Lock()
+	defer m.mu.Unlock()
 
 	var c = m.Cgroups
 
@@ -114,8 +114,8 @@ func (m *Manager) Apply(pid int) (err error) {
 		return err
 	}
 
+	m.Paths = make(map[string]string)
 	if c.Paths != nil {
-		paths := make(map[string]string)
 		for name, path := range c.Paths {
 			_, err := d.path(name)
 			if err != nil {
@@ -124,32 +124,30 @@ func (m *Manager) Apply(pid int) (err error) {
 				}
 				return err
 			}
-			paths[name] = path
+			m.Paths[name] = path
 		}
-		m.Paths = paths
 		return cgroups.EnterPid(m.Paths, pid)
 	}
 
-	m.mu.Lock()
-	defer m.mu.Unlock()
-	paths := make(map[string]string)
 	for _, sys := range subsystems {
-		if err := sys.Apply(d); err != nil {
-			return err
-		}
 		// TODO: Apply should, ideally, be reentrant or be broken up into a separate
 		// create and join phase so that the cgroup hierarchy for a container can be
 		// created then join consists of writing the process pids to cgroup.procs
 		p, err := d.path(sys.Name())
 		if err != nil {
-			if cgroups.IsNotFound(err) {
+			// The non-presence of the devices subsystem is
+			// considered fatal for security reasons.
+			if cgroups.IsNotFound(err) && sys.Name() != "devices" {
 				continue
 			}
 			return err
 		}
-		paths[sys.Name()] = p
+		m.Paths[sys.Name()] = p
+
+		if err := sys.Apply(d); err != nil {
+			return err
+		}
 	}
-	m.Paths = paths
 	return nil
 }
 
@@ -190,18 +188,15 @@ func (m *Manager) GetStats() (*cgroups.Stats, error) {
 }
 
 func (m *Manager) Set(container *configs.Config) error {
-	for _, sys := range subsystems {
-		// Generate fake cgroup data.
-		d, err := getCgroupData(container.Cgroups, -1)
-		if err != nil {
-			return err
-		}
-		// Get the path, but don't error out if the cgroup wasn't found.
-		path, err := d.path(sys.Name())
-		if err != nil && !cgroups.IsNotFound(err) {
-			return err
-		}
+	// If Paths are set, then we are just joining cgroups paths
+	// and there is no need to set any values.
+	if m.Cgroups.Paths != nil {
+		return nil
+	}
 
+	paths := m.GetPaths()
+	for _, sys := range subsystems {
+		path := paths[sys.Name()]
 		if err := sys.Set(path, container.Cgroups); err != nil {
 			return err
 		}
@@ -218,14 +213,8 @@ func (m *Manager) Set(container *configs.Config) error {
 // Freeze toggles the container's freezer cgroup depending on the state
 // provided
 func (m *Manager) Freeze(state configs.FreezerState) error {
-	d, err := getCgroupData(m.Cgroups, 0)
-	if err != nil {
-		return err
-	}
-	dir, err := d.path("freezer")
-	if err != nil {
-		return err
-	}
+	paths := m.GetPaths()
+	dir := paths["freezer"]
 	prevState := m.Cgroups.Resources.Freezer
 	m.Cgroups.Resources.Freezer = state
 	freezer, err := subsystems.Get("freezer")
@@ -241,28 +230,13 @@ func (m *Manager) Freeze(state configs.FreezerState) error {
 }
 
 func (m *Manager) GetPids() ([]int, error) {
-	dir, err := getCgroupPath(m.Cgroups)
-	if err != nil {
-		return nil, err
-	}
-	return cgroups.GetPids(dir)
+	paths := m.GetPaths()
+	return cgroups.GetPids(paths["devices"])
 }
 
 func (m *Manager) GetAllPids() ([]int, error) {
-	dir, err := getCgroupPath(m.Cgroups)
-	if err != nil {
-		return nil, err
-	}
-	return cgroups.GetAllPids(dir)
-}
-
-func getCgroupPath(c *configs.Cgroup) (string, error) {
-	d, err := getCgroupData(c, 0)
-	if err != nil {
-		return "", err
-	}
-
-	return d.path("devices")
+	paths := m.GetPaths()
+	return cgroups.GetAllPids(paths["devices"])
 }
 
 func getCgroupData(c *configs.Cgroup, pid int) (*cgroupData, error) {
@@ -319,7 +293,7 @@ func (raw *cgroupData) path(subsystem string) (string, error) {
 
 	// If the cgroup name/path is absolute do not look relative to the cgroup of the init process.
 	if filepath.IsAbs(raw.innerPath) {
-		// Sometimes subsystems can be mounted togethger as 'cpu,cpuacct'.
+		// Sometimes subsystems can be mounted together as 'cpu,cpuacct'.
 		return filepath.Join(raw.root, filepath.Base(mnt), raw.innerPath), nil
 	}
 
@@ -339,7 +313,7 @@ func (raw *cgroupData) join(subsystem string) (string, error) {
 	if err := os.MkdirAll(path, 0755); err != nil {
 		return "", err
 	}
-	if err := writeFile(path, CgroupProcesses, strconv.Itoa(raw.pid)); err != nil {
+	if err := cgroups.WriteCgroupProc(path, raw.pid); err != nil {
 		return "", err
 	}
 	return path, nil
@@ -349,7 +323,7 @@ func writeFile(dir, file, data string) error {
 	// Normally dir should not be empty, one case is that cgroup subsystem
 	// is not mounted, we will get empty dir, and we want it fail here.
 	if dir == "" {
-		return fmt.Errorf("no such directory for %s.", file)
+		return fmt.Errorf("no such directory for %s", file)
 	}
 	if err := ioutil.WriteFile(filepath.Join(dir, file), []byte(data), 0700); err != nil {
 		return fmt.Errorf("failed to write %v to %v: %v", data, file, err)

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/cpu.go

@@ -22,10 +22,48 @@ func (s *CpuGroup) Name() string {
 func (s *CpuGroup) Apply(d *cgroupData) error {
 	// We always want to join the cpu group, to allow fair cpu scheduling
 	// on a container basis
-	_, err := d.join("cpu")
+	path, err := d.path("cpu")
 	if err != nil && !cgroups.IsNotFound(err) {
 		return err
 	}
+	return s.ApplyDir(path, d.config, d.pid)
+}
+
+func (s *CpuGroup) ApplyDir(path string, cgroup *configs.Cgroup, pid int) error {
+	// This might happen if we have no cpu cgroup mounted.
+	// Just do nothing and don't fail.
+	if path == "" {
+		return nil
+	}
+	if err := os.MkdirAll(path, 0755); err != nil {
+		return err
+	}
+	// We should set the real-Time group scheduling settings before moving
+	// in the process because if the process is already in SCHED_RR mode
+	// and no RT bandwidth is set, adding it will fail.
+	if err := s.SetRtSched(path, cgroup); err != nil {
+		return err
+	}
+	// because we are not using d.join we need to place the pid into the procs file
+	// unlike the other subsystems
+	if err := cgroups.WriteCgroupProc(path, pid); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (s *CpuGroup) SetRtSched(path string, cgroup *configs.Cgroup) error {
+	if cgroup.Resources.CpuRtPeriod != 0 {
+		if err := writeFile(path, "cpu.rt_period_us", strconv.FormatInt(cgroup.Resources.CpuRtPeriod, 10)); err != nil {
+			return err
+		}
+	}
+	if cgroup.Resources.CpuRtRuntime != 0 {
+		if err := writeFile(path, "cpu.rt_runtime_us", strconv.FormatInt(cgroup.Resources.CpuRtRuntime, 10)); err != nil {
+			return err
+		}
+	}
 	return nil
 }
 
@@ -45,15 +83,8 @@ func (s *CpuGroup) Set(path string, cgroup *configs.Cgroup) error {
 			return err
 		}
 	}
-	if cgroup.Resources.CpuRtPeriod != 0 {
-		if err := writeFile(path, "cpu.rt_period_us", strconv.FormatInt(cgroup.Resources.CpuRtPeriod, 10)); err != nil {
-			return err
-		}
-	}
-	if cgroup.Resources.CpuRtRuntime != 0 {
-		if err := writeFile(path, "cpu.rt_runtime_us", strconv.FormatInt(cgroup.Resources.CpuRtRuntime, 10)); err != nil {
-			return err
-		}
+	if err := s.SetRtSched(path, cgroup); err != nil {
+		return err
 	}
 
 	return nil

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/cpu_test.go

@@ -106,13 +106,13 @@ func TestCpuStats(t *testing.T) {
 	defer helper.cleanup()
 
 	const (
-		kNrPeriods     = 2000
-		kNrThrottled   = 200
-		kThrottledTime = uint64(18446744073709551615)
+		nrPeriods     = 2000
+		nrThrottled   = 200
+		throttledTime = uint64(18446744073709551615)
 	)
 
 	cpuStatContent := fmt.Sprintf("nr_periods %d\n nr_throttled %d\n throttled_time %d\n",
-		kNrPeriods, kNrThrottled, kThrottledTime)
+		nrPeriods, nrThrottled, throttledTime)
 	helper.writeFileContents(map[string]string{
 		"cpu.stat": cpuStatContent,
 	})
@@ -125,9 +125,9 @@ func TestCpuStats(t *testing.T) {
 	}
 
 	expectedStats := cgroups.ThrottlingData{
-		Periods:          kNrPeriods,
-		ThrottledPeriods: kNrThrottled,
-		ThrottledTime:    kThrottledTime}
+		Periods:          nrPeriods,
+		ThrottledPeriods: nrThrottled,
+		ThrottledTime:    throttledTime}
 
 	expectThrottlingDataEquals(t, expectedStats, actualStats.CpuStats.ThrottlingData)
 }
@@ -161,3 +161,49 @@ func TestInvalidCpuStat(t *testing.T) {
 		t.Fatal("Expected failed stat parsing.")
 	}
 }
+
+func TestCpuSetRtSchedAtApply(t *testing.T) {
+	helper := NewCgroupTestUtil("cpu", t)
+	defer helper.cleanup()
+
+	const (
+		rtRuntimeBefore = 0
+		rtRuntimeAfter  = 5000
+		rtPeriodBefore  = 0
+		rtPeriodAfter   = 7000
+	)
+
+	helper.writeFileContents(map[string]string{
+		"cpu.rt_runtime_us": strconv.Itoa(rtRuntimeBefore),
+		"cpu.rt_period_us":  strconv.Itoa(rtPeriodBefore),
+	})
+
+	helper.CgroupData.config.Resources.CpuRtRuntime = rtRuntimeAfter
+	helper.CgroupData.config.Resources.CpuRtPeriod = rtPeriodAfter
+	cpu := &CpuGroup{}
+	if err := cpu.ApplyDir(helper.CgroupPath, helper.CgroupData.config, 1234); err != nil {
+		t.Fatal(err)
+	}
+
+	rtRuntime, err := getCgroupParamUint(helper.CgroupPath, "cpu.rt_runtime_us")
+	if err != nil {
+		t.Fatalf("Failed to parse cpu.rt_runtime_us - %s", err)
+	}
+	if rtRuntime != rtRuntimeAfter {
+		t.Fatal("Got the wrong value, set cpu.rt_runtime_us failed.")
+	}
+	rtPeriod, err := getCgroupParamUint(helper.CgroupPath, "cpu.rt_period_us")
+	if err != nil {
+		t.Fatalf("Failed to parse cpu.rt_period_us - %s", err)
+	}
+	if rtPeriod != rtPeriodAfter {
+		t.Fatal("Got the wrong value, set cpu.rt_period_us failed.")
+	}
+	pid, err := getCgroupParamUint(helper.CgroupPath, "cgroup.procs")
+	if err != nil {
+		t.Fatalf("Failed to parse cgroup.procs - %s", err)
+	}
+	if pid != 1234 {
+		t.Fatal("Got the wrong value, set cgroup.procs failed.")
+	}
+}

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/cpuset.go

@@ -8,7 +8,6 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"strconv"
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
@@ -62,12 +61,29 @@ func (s *CpusetGroup) ApplyDir(dir string, cgroup *configs.Cgroup, pid int) erro
 	if err != nil {
 		return err
 	}
-	if err := s.ensureParent(dir, root); err != nil {
+	// 'ensureParent' start with parent because we don't want to
+	// explicitly inherit from parent, it could conflict with
+	// 'cpuset.cpu_exclusive'.
+	if err := s.ensureParent(filepath.Dir(dir), root); err != nil {
 		return err
 	}
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return err
+	}
+	// We didn't inherit cpuset configs from parent, but we have
+	// to ensure cpuset configs are set before moving task into the
+	// cgroup.
+	// The logic is, if user specified cpuset configs, use these
+	// specified configs, otherwise, inherit from parent. This makes
+	// cpuset configs work correctly with 'cpuset.cpu_exclusive', and
+	// keep backward compatbility.
+	if err := s.ensureCpusAndMems(dir, cgroup); err != nil {
+		return err
+	}
+
 	// because we are not using d.join we need to place the pid into the procs file
 	// unlike the other subsystems
-	if err := writeFile(dir, "cgroup.procs", strconv.Itoa(pid)); err != nil {
+	if err := cgroups.WriteCgroupProc(dir, pid); err != nil {
 		return err
 	}
 
@@ -137,3 +153,10 @@ func (s *CpusetGroup) copyIfNeeded(current, parent string) error {
 func (s *CpusetGroup) isEmpty(b []byte) bool {
 	return len(bytes.Trim(b, "\n")) == 0
 }
+
+func (s *CpusetGroup) ensureCpusAndMems(path string, cgroup *configs.Cgroup) error {
+	if err := s.Set(path, cgroup); err != nil {
+		return err
+	}
+	return s.copyIfNeeded(path, filepath.Dir(path))
+}

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/devices.go

@@ -43,21 +43,23 @@ func (s *DevicesGroup) Set(path string, cgroup *configs.Cgroup) error {
 		}
 		return nil
 	}
-	if !cgroup.Resources.AllowAllDevices {
-		if err := writeFile(path, "devices.deny", "a"); err != nil {
-			return err
-		}
-
-		for _, dev := range cgroup.Resources.AllowedDevices {
-			if err := writeFile(path, "devices.allow", dev.CgroupString()); err != nil {
+	if cgroup.Resources.AllowAllDevices != nil {
+		if *cgroup.Resources.AllowAllDevices == false {
+			if err := writeFile(path, "devices.deny", "a"); err != nil {
 				return err
 			}
-		}
-		return nil
-	}
 
-	if err := writeFile(path, "devices.allow", "a"); err != nil {
-		return err
+			for _, dev := range cgroup.Resources.AllowedDevices {
+				if err := writeFile(path, "devices.allow", dev.CgroupString()); err != nil {
+					return err
+				}
+			}
+			return nil
+		}
+
+		if err := writeFile(path, "devices.allow", "a"); err != nil {
+			return err
+		}
 	}
 
 	for _, dev := range cgroup.Resources.DeniedDevices {

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/devices_test.go

@@ -40,8 +40,8 @@ func TestDevicesSetAllow(t *testing.T) {
 	helper.writeFileContents(map[string]string{
 		"devices.deny": "a",
 	})
-
-	helper.CgroupData.config.Resources.AllowAllDevices = false
+	allowAllDevices := false
+	helper.CgroupData.config.Resources.AllowAllDevices = &allowAllDevices
 	helper.CgroupData.config.Resources.AllowedDevices = allowedDevices
 	devices := &DevicesGroup{}
 	if err := devices.Set(helper.CgroupPath, helper.CgroupData.config); err != nil {
@@ -56,6 +56,19 @@ func TestDevicesSetAllow(t *testing.T) {
 	if value != allowedList {
 		t.Fatal("Got the wrong value, set devices.allow failed.")
 	}
+
+	// When AllowAllDevices is nil, devices.allow file should not be modified.
+	helper.CgroupData.config.Resources.AllowAllDevices = nil
+	if err := devices.Set(helper.CgroupPath, helper.CgroupData.config); err != nil {
+		t.Fatal(err)
+	}
+	value, err = getCgroupParamString(helper.CgroupPath, "devices.allow")
+	if err != nil {
+		t.Fatalf("Failed to parse devices.allow - %s", err)
+	}
+	if value != allowedList {
+		t.Fatal("devices policy shouldn't have changed on AllowedAllDevices=nil.")
+	}
 }
 
 func TestDevicesSetDeny(t *testing.T) {
@@ -66,7 +79,8 @@ func TestDevicesSetDeny(t *testing.T) {
 		"devices.allow": "a",
 	})
 
-	helper.CgroupData.config.Resources.AllowAllDevices = true
+	allowAllDevices := true
+	helper.CgroupData.config.Resources.AllowAllDevices = &allowAllDevices
 	helper.CgroupData.config.Resources.DeniedDevices = deniedDevices
 	devices := &DevicesGroup{}
 	if err := devices.Set(helper.CgroupPath, helper.CgroupData.config); err != nil {

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/memory.go

@@ -5,15 +5,19 @@ package fs
 import (
 	"bufio"
 	"fmt"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
+	"syscall"
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
 )
 
+const cgroupKernelMemoryLimit = "memory.kmem.limit_in_bytes"
+
 type MemoryGroup struct {
 }
 
@@ -32,13 +36,12 @@ func (s *MemoryGroup) Apply(d *cgroupData) (err error) {
 				return err
 			}
 		}
-		// We have to set kernel memory here, as we can't change it once
-		// processes have been attached.
-		if err := s.SetKernelMemory(path, d.config); err != nil {
-			return err
+		if d.config.KernelMemory != 0 {
+			if err := EnableKernelMemoryAccounting(path); err != nil {
+				return err
+			}
 		}
 	}
-
 	defer func() {
 		if err != nil {
 			os.RemoveAll(path)
@@ -54,17 +57,44 @@ func (s *MemoryGroup) Apply(d *cgroupData) (err error) {
 	return nil
 }
 
-func (s *MemoryGroup) SetKernelMemory(path string, cgroup *configs.Cgroup) error {
-	// This has to be done separately because it has special constraints (it
-	// can't be done after there are processes attached to the cgroup).
-	if cgroup.Resources.KernelMemory > 0 {
-		if err := writeFile(path, "memory.kmem.limit_in_bytes", strconv.FormatInt(cgroup.Resources.KernelMemory, 10)); err != nil {
+func EnableKernelMemoryAccounting(path string) error {
+	// Check if kernel memory is enabled
+	// We have to limit the kernel memory here as it won't be accounted at all
+	// until a limit is set on the cgroup and limit cannot be set once the
+	// cgroup has children, or if there are already tasks in the cgroup.
+	for _, i := range []int64{1, -1} {
+		if err := setKernelMemory(path, i); err != nil {
 			return err
 		}
 	}
 	return nil
 }
 
+func setKernelMemory(path string, kernelMemoryLimit int64) error {
+	if path == "" {
+		return fmt.Errorf("no such directory for %s", cgroupKernelMemoryLimit)
+	}
+	if !cgroups.PathExists(filepath.Join(path, cgroupKernelMemoryLimit)) {
+		// kernel memory is not enabled on the system so we should do nothing
+		return nil
+	}
+	if err := ioutil.WriteFile(filepath.Join(path, cgroupKernelMemoryLimit), []byte(strconv.FormatInt(kernelMemoryLimit, 10)), 0700); err != nil {
+		// Check if the error number returned by the syscall is "EBUSY"
+		// The EBUSY signal is returned on attempts to write to the
+		// memory.kmem.limit_in_bytes file if the cgroup has children or
+		// once tasks have been attached to the cgroup
+		if pathErr, ok := err.(*os.PathError); ok {
+			if errNo, ok := pathErr.Err.(syscall.Errno); ok {
+				if errNo == syscall.EBUSY {
+					return fmt.Errorf("failed to set %s, because either tasks have already joined this cgroup or it has children", cgroupKernelMemoryLimit)
+				}
+			}
+		}
+		return fmt.Errorf("failed to write %v to %v: %v", kernelMemoryLimit, cgroupKernelMemoryLimit, err)
+	}
+	return nil
+}
+
 func setMemoryAndSwap(path string, cgroup *configs.Cgroup) error {
 	// When memory and swap memory are both set, we need to handle the cases
 	// for updating container.
@@ -113,11 +143,18 @@ func (s *MemoryGroup) Set(path string, cgroup *configs.Cgroup) error {
 		return err
 	}
 
+	if cgroup.Resources.KernelMemory != 0 {
+		if err := setKernelMemory(path, cgroup.Resources.KernelMemory); err != nil {
+			return err
+		}
+	}
+
 	if cgroup.Resources.MemoryReservation != 0 {
 		if err := writeFile(path, "memory.soft_limit_in_bytes", strconv.FormatInt(cgroup.Resources.MemoryReservation, 10)); err != nil {
 			return err
 		}
 	}
+
 	if cgroup.Resources.KernelMemoryTCP != 0 {
 		if err := writeFile(path, "memory.kmem.tcp.limit_in_bytes", strconv.FormatInt(cgroup.Resources.KernelMemoryTCP, 10)); err != nil {
 			return err

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/memory_test.go

@@ -230,7 +230,7 @@ func TestMemorySetKernelMemory(t *testing.T) {
 
 	helper.CgroupData.config.Resources.KernelMemory = kernelMemoryAfter
 	memory := &MemoryGroup{}
-	if err := memory.SetKernelMemory(helper.CgroupPath, helper.CgroupData.config); err != nil {
+	if err := memory.Set(helper.CgroupPath, helper.CgroupData.config); err != nil {
 		t.Fatal(err)
 	}
 
@@ -471,11 +471,11 @@ func TestMemorySetOomControl(t *testing.T) {
 	defer helper.cleanup()
 
 	const (
-		oom_kill_disable = 1 // disable oom killer, default is 0
+		oomKillDisable = 1 // disable oom killer, default is 0
 	)
 
 	helper.writeFileContents(map[string]string{
-		"memory.oom_control": strconv.Itoa(oom_kill_disable),
+		"memory.oom_control": strconv.Itoa(oomKillDisable),
 	})
 
 	memory := &MemoryGroup{}
@@ -488,7 +488,7 @@ func TestMemorySetOomControl(t *testing.T) {
 		t.Fatalf("Failed to parse memory.oom_control - %s", err)
 	}
 
-	if value != oom_kill_disable {
+	if value != oomKillDisable {
 		t.Fatalf("Got the wrong value, set memory.oom_control failed.")
 	}
 }

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/net_cls.go

@@ -3,6 +3,8 @@
 package fs
 
 import (
+	"strconv"
+
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
 )
@@ -23,8 +25,8 @@ func (s *NetClsGroup) Apply(d *cgroupData) error {
 }
 
 func (s *NetClsGroup) Set(path string, cgroup *configs.Cgroup) error {
-	if cgroup.Resources.NetClsClassid != "" {
-		if err := writeFile(path, "net_cls.classid", cgroup.Resources.NetClsClassid); err != nil {
+	if cgroup.Resources.NetClsClassid != 0 {
+		if err := writeFile(path, "net_cls.classid", strconv.FormatUint(uint64(cgroup.Resources.NetClsClassid), 10)); err != nil {
 			return err
 		}
 	}

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/net_cls_test.go

@@ -3,12 +3,13 @@
 package fs
 
 import (
+	"strconv"
 	"testing"
 )
 
 const (
-	classidBefore = "0x100002"
-	classidAfter  = "0x100001"
+	classidBefore = 0x100002
+	classidAfter  = 0x100001
 )
 
 func TestNetClsSetClassid(t *testing.T) {
@@ -16,7 +17,7 @@ func TestNetClsSetClassid(t *testing.T) {
 	defer helper.cleanup()
 
 	helper.writeFileContents(map[string]string{
-		"net_cls.classid": classidBefore,
+		"net_cls.classid": strconv.FormatUint(classidBefore, 10),
 	})
 
 	helper.CgroupData.config.Resources.NetClsClassid = classidAfter
@@ -28,7 +29,7 @@ func TestNetClsSetClassid(t *testing.T) {
 	// As we are in mock environment, we can't get correct value of classid from
 	// net_cls.classid.
 	// So. we just judge if we successfully write classid into file
-	value, err := getCgroupParamString(helper.CgroupPath, "net_cls.classid")
+	value, err := getCgroupParamUint(helper.CgroupPath, "net_cls.classid")
 	if err != nil {
 		t.Fatalf("Failed to parse net_cls.classid - %s", err)
 	}

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/utils.go

@@ -12,7 +12,6 @@ import (
 )
 
 var (
-	ErrNotSupportStat = errors.New("stats are not supported for subsystem")
 	ErrNotValidFormat = errors.New("line is not a valid key value format")
 )