cgroupv1/freezer: don't use subsystemSet.Get()

Iterating over the list of subsystems and comparing their names to get an instance of fs.cgroupFreezer is useless and a waste of time, since it is a shallow type (i.e. does not have any data/state) and we can create an instance in place. Signed-off-by: Kir Kolyshkin <[email protected]>
ctalledo · Jul 3, 2020 · cd479f9 · cd479f9
1 parent 3cb1909
commit cd479f9
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Showing 2 changed files with 7 additions and 17 deletions.
diff --git a/libcontainer/cgroups/fs/fs.go b/libcontainer/cgroups/fs/fs.go
@@ -312,10 +312,7 @@ func (m *manager) Freeze(state configs.FreezerState) (Err error) {
 		}
 	}()
 
-	freezer, err := m.getSubsystems().Get("freezer")
-	if err != nil {
-		return err
-	}
+	freezer := &FreezerGroup{}
 	if err := freezer.Set(path, m.cgroups); err != nil {
 		return err
 	}
@@ -418,13 +415,12 @@ func (m *manager) GetCgroups() (*configs.Cgroup, error) {
 
 func (m *manager) GetFreezerState() (configs.FreezerState, error) {
 	dir := m.Path("freezer")
-	freezer, err := m.getSubsystems().Get("freezer")
-
 	// If the container doesn't have the freezer cgroup, say it's undefined.
-	if err != nil || dir == "" {
+	if dir == "" {
 		return configs.Undefined, nil
 	}
-	return freezer.(*FreezerGroup).GetState(dir)
+	freezer := &FreezerGroup{}
+	return freezer.GetState(dir)
 }
 
 func (m *manager) Exists() bool {

diff --git a/libcontainer/cgroups/systemd/v1.go b/libcontainer/cgroups/systemd/v1.go
@@ -319,10 +319,7 @@ func (m *legacyManager) Freeze(state configs.FreezerState) error {
 	}
 	prevState := m.cgroups.Resources.Freezer
 	m.cgroups.Resources.Freezer = state
-	freezer, err := legacySubsystems.Get("freezer")
-	if err != nil {
-		return err
-	}
+	freezer := &fs.FreezerGroup{}
 	err = freezer.Set(path, m.cgroups)
 	if err != nil {
 		m.cgroups.Resources.Freezer = prevState
@@ -458,11 +455,8 @@ func (m *legacyManager) GetFreezerState() (configs.FreezerState, error) {
 	if err != nil && !cgroups.IsNotFound(err) {
 		return configs.Undefined, err
 	}
-	freezer, err := legacySubsystems.Get("freezer")
-	if err != nil {
-		return configs.Undefined, err
-	}
-	return freezer.(*fs.FreezerGroup).GetState(path)
+	freezer := &fs.FreezerGroup{}
+	return freezer.GetState(path)
 }
 
 func (m *legacyManager) Exists() bool {