support cgroup v1 mounted with noprefix

Author: Tomasz Duda

libcontainer/cgroups/fs/cpuset.go

@@ -1,11 +1,13 @@
 package fs
 
 import (
+	"bufio"
 	"errors"
 	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
+	"sync"
 
 	"golang.org/x/sys/unix"
 
@@ -14,6 +16,41 @@ import (
 	"github.com/opencontainers/runc/libcontainer/configs"
 )
 
+var (
+	cpusetLock   sync.Mutex
+	cpusetPrefix string
+	cpusetInit   bool
+)
+
+func getCpusetPrefix() string {
+	cpusetLock.Lock()
+	defer cpusetLock.Unlock()
+
+	if cpusetInit {
+		return cpusetPrefix
+	}
+
+	cpusetInit = true
+	cpusetPrefix = "cpuset."
+
+	file, err := os.Open("/proc/self/mountinfo")
+	if err != nil {
+		return cpusetPrefix
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.Contains(line, "cpuset") && strings.Contains(line, "cgroup") && strings.Contains(line, "noprefix") {
+			cpusetPrefix = ""
+			break
+		}
+	}
+	return cpusetPrefix
+}
+
 type CpusetGroup struct{}
 
 func (s *CpusetGroup) Name() string {
@@ -26,12 +63,12 @@ func (s *CpusetGroup) Apply(path string, r *configs.Resources, pid int) error {
 
 func (s *CpusetGroup) Set(path string, r *configs.Resources) error {
 	if r.CpusetCpus != "" {
-		if err := cgroups.WriteFile(path, "cpuset.cpus", r.CpusetCpus); err != nil {
+		if err := cgroups.WriteFile(path, getCpusetPrefix()+"cpus", r.CpusetCpus); err != nil {
 			return err
 		}
 	}
 	if r.CpusetMems != "" {
-		if err := cgroups.WriteFile(path, "cpuset.mems", r.CpusetMems); err != nil {
+		if err := cgroups.WriteFile(path, getCpusetPrefix()+"mems", r.CpusetMems); err != nil {
 			return err
 		}
 	}
@@ -83,57 +120,57 @@ func getCpusetStat(path string, file string) ([]uint16, error) {
 func (s *CpusetGroup) GetStats(path string, stats *cgroups.Stats) error {
 	var err error
 
-	stats.CPUSetStats.CPUs, err = getCpusetStat(path, "cpuset.cpus")
+	stats.CPUSetStats.CPUs, err = getCpusetStat(path, getCpusetPrefix()+"cpus")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.CPUExclusive, err = fscommon.GetCgroupParamUint(path, "cpuset.cpu_exclusive")
+	stats.CPUSetStats.CPUExclusive, err = fscommon.GetCgroupParamUint(path, getCpusetPrefix()+"cpu_exclusive")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.Mems, err = getCpusetStat(path, "cpuset.mems")
+	stats.CPUSetStats.Mems, err = getCpusetStat(path, getCpusetPrefix()+"mems")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.MemHardwall, err = fscommon.GetCgroupParamUint(path, "cpuset.mem_hardwall")
+	stats.CPUSetStats.MemHardwall, err = fscommon.GetCgroupParamUint(path, getCpusetPrefix()+"mem_hardwall")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.MemExclusive, err = fscommon.GetCgroupParamUint(path, "cpuset.mem_exclusive")
+	stats.CPUSetStats.MemExclusive, err = fscommon.GetCgroupParamUint(path, getCpusetPrefix()+"mem_exclusive")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.MemoryMigrate, err = fscommon.GetCgroupParamUint(path, "cpuset.memory_migrate")
+	stats.CPUSetStats.MemoryMigrate, err = fscommon.GetCgroupParamUint(path, getCpusetPrefix()+"memory_migrate")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.MemorySpreadPage, err = fscommon.GetCgroupParamUint(path, "cpuset.memory_spread_page")
+	stats.CPUSetStats.MemorySpreadPage, err = fscommon.GetCgroupParamUint(path, getCpusetPrefix()+"memory_spread_page")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.MemorySpreadSlab, err = fscommon.GetCgroupParamUint(path, "cpuset.memory_spread_slab")
+	stats.CPUSetStats.MemorySpreadSlab, err = fscommon.GetCgroupParamUint(path, getCpusetPrefix()+"memory_spread_slab")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.MemoryPressure, err = fscommon.GetCgroupParamUint(path, "cpuset.memory_pressure")
+	stats.CPUSetStats.MemoryPressure, err = fscommon.GetCgroupParamUint(path, getCpusetPrefix()+"memory_pressure")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.SchedLoadBalance, err = fscommon.GetCgroupParamUint(path, "cpuset.sched_load_balance")
+	stats.CPUSetStats.SchedLoadBalance, err = fscommon.GetCgroupParamUint(path, getCpusetPrefix()+"sched_load_balance")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
-	stats.CPUSetStats.SchedRelaxDomainLevel, err = fscommon.GetCgroupParamInt(path, "cpuset.sched_relax_domain_level")
+	stats.CPUSetStats.SchedRelaxDomainLevel, err = fscommon.GetCgroupParamInt(path, getCpusetPrefix()+"sched_relax_domain_level")
 	if err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
@@ -172,10 +209,10 @@ func (s *CpusetGroup) ApplyDir(dir string, r *configs.Resources, pid int) error
 }
 
 func getCpusetSubsystemSettings(parent string) (cpus, mems string, err error) {
-	if cpus, err = cgroups.ReadFile(parent, "cpuset.cpus"); err != nil {
+	if cpus, err = cgroups.ReadFile(parent, getCpusetPrefix()+"cpus"); err != nil {
 		return
 	}
-	if mems, err = cgroups.ReadFile(parent, "cpuset.mems"); err != nil {
+	if mems, err = cgroups.ReadFile(parent, getCpusetPrefix()+"mems"); err != nil {
 		return
 	}
 	return cpus, mems, nil
@@ -221,12 +258,12 @@ func cpusetCopyIfNeeded(current, parent string) error {
 	}
 
 	if isEmptyCpuset(currentCpus) {
-		if err := cgroups.WriteFile(current, "cpuset.cpus", parentCpus); err != nil {
+		if err := cgroups.WriteFile(current, getCpusetPrefix()+"cpus", parentCpus); err != nil {
 			return err
 		}
 	}
 	if isEmptyCpuset(currentMems) {
-		if err := cgroups.WriteFile(current, "cpuset.mems", parentMems); err != nil {
+		if err := cgroups.WriteFile(current, getCpusetPrefix()+"mems", parentMems); err != nil {
 			return err
 		}
 	}