pkg/cgroups/createCgroupv2Path: nits

1. Check the path validity before trying to read the cgroup.controllers.

2. Do not hardcode "/sys/fs/cgroup".

3. Simplify creating the "+this +that" string.

4. Do not wrap ioutil.WriteFile error.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin
2020-10-05 12:41:28 -07:00
parent 684d0079d2
commit d4aa89bb40

View File

@ -2,6 +2,7 @@ package cgroups
import (
"bufio"
"bytes"
"fmt"
"io/ioutil"
"math"
@ -155,23 +156,15 @@ func (c *CgroupControl) getCgroupv1Path(name string) string {
// createCgroupv2Path creates the cgroupv2 path and enables all the available controllers
func createCgroupv2Path(path string) (deferredError error) {
content, err := ioutil.ReadFile("/sys/fs/cgroup/cgroup.controllers")
if !strings.HasPrefix(path, cgroupRoot+"/") {
return fmt.Errorf("invalid cgroup path %s", path)
}
content, err := ioutil.ReadFile(cgroupRoot + "/cgroup.controllers")
if err != nil {
return err
}
if !strings.HasPrefix(path, "/sys/fs/cgroup/") {
return fmt.Errorf("invalid cgroup path %s", path)
}
res := ""
for i, c := range strings.Split(strings.TrimSpace(string(content)), " ") {
if i == 0 {
res = fmt.Sprintf("+%s", c)
} else {
res += fmt.Sprintf(" +%s", c)
}
}
resByte := []byte(res)
ctrs := bytes.Fields(content)
res := append([]byte("+"), bytes.Join(ctrs, []byte(" +"))...)
current := "/sys/fs"
elements := strings.Split(path, "/")
@ -194,8 +187,8 @@ func createCgroupv2Path(path string) (deferredError error) {
// We enable the controllers for all the path components except the last one. It is not allowed to add
// PIDs if there are already enabled controllers.
if i < len(elements[3:])-1 {
if err := ioutil.WriteFile(filepath.Join(current, "cgroup.subtree_control"), resByte, 0755); err != nil {
return errors.Wrapf(err, "write %s", filepath.Join(current, "cgroup.subtree_control"))
if err := ioutil.WriteFile(filepath.Join(current, "cgroup.subtree_control"), res, 0755); err != nil {
return err
}
}
}