Revert "CreateCgroupPath: only enable needed controllers"

1. Partially revert "CreateCgroupPath: only enable needed controllers"
If we update a resource which did not limited in the beginning,
it will have no effective.
2. Returns err if we use an non enabled controller,
or else the user may feel success, but actually there are no effective.

Signed-off-by: lifubang <lifubang@acmcoder.com>

libcontainer/cgroups/fs2/create.go

@@ -1,6 +1,7 @@
 package fs2
 
 import (
+	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -10,57 +11,56 @@ import (
 	"github.com/opencontainers/runc/libcontainer/configs"
 )
 
-// neededControllers returns the string to write to cgroup.subtree_control,
-// containing the list of controllers to enable (for example, "+cpu +pids"),
-// based on (1) controllers available and (2) resources that are being set.
-//
-// The resulting string does not include "pseudo" controllers such as
-// "freezer" and "devices".
-func neededControllers(cgroup *configs.Cgroup) ([]string, error) {
-	var list []string
+func supportedControllers(cgroup *configs.Cgroup) ([]byte, error) {
+	const file = UnifiedMountpoint + "/cgroup.controllers"
+	return ioutil.ReadFile(file)
+}
 
+// needAnyControllers returns whether we enable some supported controllers or not,
+// based on (1) controllers available and (2) resources that are being set.
+// We don't check "pseudo" controllers such as
+// "freezer" and "devices".
+func needAnyControllers(cgroup *configs.Cgroup) (bool, error) {
 	if cgroup == nil {
-		return list, nil
+		return false, nil
 	}
 
 	// list of all available controllers
-	const file = UnifiedMountpoint + "/cgroup.controllers"
-	content, err := ioutil.ReadFile(file)
+	content, err := supportedControllers(cgroup)
 	if err != nil {
-		return list, err
+		return false, err
 	}
 	avail := make(map[string]struct{})
 	for _, ctr := range strings.Fields(string(content)) {
 		avail[ctr] = struct{}{}
 	}
 
-	// add the controller if available
-	add := func(controller string) {
-		if _, ok := avail[controller]; ok {
-			list = append(list, "+"+controller)
-		}
+	// check whether the controller if available or not
+	have := func(controller string) bool {
+		_, ok := avail[controller]
+		return ok
 	}
 
-	if isPidsSet(cgroup) {
-		add("pids")
+	if isPidsSet(cgroup) && have("pids") {
+		return true, nil
 	}
-	if isMemorySet(cgroup) {
-		add("memory")
+	if isMemorySet(cgroup) && have("memory") {
+		return true, nil
 	}
-	if isIoSet(cgroup) {
-		add("io")
+	if isIoSet(cgroup) && have("io") {
+		return true, nil
 	}
-	if isCpuSet(cgroup) {
-		add("cpu")
+	if isCpuSet(cgroup) && have("cpu") {
+		return true, nil
 	}
-	if isCpusetSet(cgroup) {
-		add("cpuset")
+	if isCpusetSet(cgroup) && have("cpuset") {
+		return true, nil
 	}
-	if isHugeTlbSet(cgroup) {
-		add("hugetlb")
+	if isHugeTlbSet(cgroup) && have("hugetlb") {
+		return true, nil
 	}
 
-	return list, nil
+	return false, nil
 }
 
 // containsDomainController returns whether the current config contains domain controller or not.
@@ -70,18 +70,19 @@ func containsDomainController(cg *configs.Cgroup) bool {
 	return isMemorySet(cg) || isIoSet(cg) || isCpuSet(cg) || isHugeTlbSet(cg)
 }
 
-// CreateCgroupPath creates cgroupv2 path, enabling all the
-// needed controllers in the process.
+// CreateCgroupPath creates cgroupv2 path, enabling all the supported controllers.
 func CreateCgroupPath(path string, c *configs.Cgroup) (Err error) {
 	if !strings.HasPrefix(path, UnifiedMountpoint) {
 		return fmt.Errorf("invalid cgroup path %s", path)
 	}
 
-	ctrs, err := neededControllers(c)
+	content, err := supportedControllers(c)
 	if err != nil {
 		return err
 	}
-	allCtrs := strings.Join(ctrs, " ")
+
+	ctrs := bytes.Fields(content)
+	res := append([]byte("+"), bytes.Join(ctrs, []byte(" +"))...)
 
 	elements := strings.Split(path, "/")
 	elements = elements[3:]
@@ -131,13 +132,14 @@ func CreateCgroupPath(path string, c *configs.Cgroup) (Err error) {
 				}
 			}
 		}
-		// enable needed controllers
+		// enable all supported controllers
 		if i < len(elements)-1 {
 			file := filepath.Join(current, "cgroup.subtree_control")
-			if err := ioutil.WriteFile(file, []byte(allCtrs), 0644); err != nil {
+			if err := ioutil.WriteFile(file, res, 0644); err != nil {
 				// try write one by one
-				for _, ctr := range ctrs {
-					_ = ioutil.WriteFile(file, []byte(ctr), 0644)
+				allCtrs := bytes.Split(res, []byte(" "))
+				for _, ctr := range allCtrs {
+					_ = ioutil.WriteFile(file, ctr, 0644)
 				}
 			}
 			// Some controllers might not be enabled when rootless or containerized,

libcontainer/cgroups/fs2/fs2.go

@@ -76,8 +76,7 @@ func (m *manager) Apply(pid int) error {
 		// - "runc create (rootless + limits + no cgrouppath + no permission) fails with informative error"
 		if m.rootless {
 			if m.config.Path == "" {
-				cl, clErr := neededControllers(m.config)
-				if clErr == nil && len(cl) == 0 {
+				if blNeed, nErr := needAnyControllers(m.config); nErr == nil && !blNeed {
 					return nil
 				}
 				return errors.Wrap(err, "rootless needs no limits + no cgrouppath when no permission is granted for cgroups")
@@ -175,30 +174,21 @@ func (m *manager) Set(container *configs.Config) error {
 	if err := m.getControllers(); err != nil {
 		return err
 	}
-	var errs []error
 	// pids (since kernel 4.5)
-	if _, ok := m.controllers["pids"]; ok {
 	if err := setPids(m.dirPath, container.Cgroups); err != nil {
-			errs = append(errs, err)
-		}
+		return err
 	}
 	// memory (since kernel 4.5)
-	if _, ok := m.controllers["memory"]; ok {
 	if err := setMemory(m.dirPath, container.Cgroups); err != nil {
-			errs = append(errs, err)
-		}
+		return err
 	}
 	// io (since kernel 4.5)
-	if _, ok := m.controllers["io"]; ok {
 	if err := setIo(m.dirPath, container.Cgroups); err != nil {
-			errs = append(errs, err)
-		}
+		return err
 	}
 	// cpu (since kernel 4.15)
-	if _, ok := m.controllers["cpu"]; ok {
 	if err := setCpu(m.dirPath, container.Cgroups); err != nil {
-			errs = append(errs, err)
-		}
+		return err
 	}
 	// devices (since kernel 4.15, pseudo-controller)
 	//
@@ -206,26 +196,19 @@ func (m *manager) Set(container *configs.Config) error {
 	// However, errors from other subsystems are not ignored.
 	// see @test "runc create (rootless + limits + no cgrouppath + no permission) fails with informative error"
 	if err := setDevices(m.dirPath, container.Cgroups); err != nil && !m.rootless {
-		errs = append(errs, err)
+		return err
 	}
 	// cpuset (since kernel 5.0)
-	if _, ok := m.controllers["cpuset"]; ok {
 	if err := setCpuset(m.dirPath, container.Cgroups); err != nil {
-			errs = append(errs, err)
-		}
+		return err
 	}
 	// hugetlb (since kernel 5.6)
-	if _, ok := m.controllers["hugetlb"]; ok {
 	if err := setHugeTlb(m.dirPath, container.Cgroups); err != nil {
-			errs = append(errs, err)
-		}
+		return err
 	}
 	// freezer (since kernel 5.2, pseudo-controller)
 	if err := setFreezer(m.dirPath, container.Cgroups.Freezer); err != nil {
-		errs = append(errs, err)
-	}
-	if len(errs) > 0 {
-		return errors.Errorf("error while setting cgroup v2: %+v", errs)
+		return err
 	}
 	m.config = container.Cgroups
 	return nil