libct/configs/validate: simplify intelrtd tests

The whole struct intelRdtStatus with its methods and a sync.Once is not
needed, since intelrtd.Is*Enabled methods are already run-once (or use
run-once and a simple comparison).

Yet it is still needed for the test to fake values returned by *Enabled.

Simplify to use func pointers which a test case overwrites.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/configs/validate/intelrdt.go

@@ -1,41 +1,12 @@
 package validate
 
 import (
-	"sync"
-
 	"github.com/opencontainers/runc/libcontainer/intelrdt"
 )
 
-// Cache the result of intelrdt IsEnabled functions to avoid repeated sysfs
-// access and enable mocking for unit tests.
-type intelRdtStatus struct {
-	sync.Once
-	rdtEnabled bool
-	catEnabled bool
-	mbaEnabled bool
-}
-
-var intelRdt = &intelRdtStatus{}
-
-func (i *intelRdtStatus) init() {
-	i.Do(func() {
-		i.rdtEnabled = intelrdt.IsEnabled()
-		i.catEnabled = intelrdt.IsCATEnabled()
-		i.mbaEnabled = intelrdt.IsMBAEnabled()
-	})
-}
-
-func (i *intelRdtStatus) isEnabled() bool {
-	i.init()
-	return i.rdtEnabled
-}
-
-func (i *intelRdtStatus) isCATEnabled() bool {
-	i.init()
-	return i.catEnabled
-}
-
-func (i *intelRdtStatus) isMBAEnabled() bool {
-	i.init()
-	return i.mbaEnabled
-}
+// Allow mocking for TestValidateIntelRdt.
+var (
+	intelRdtIsEnabled    = intelrdt.IsEnabled
+	intelRdtIsCATEnabled = intelrdt.IsCATEnabled
+	intelRdtIsMBAEnabled = intelrdt.IsMBAEnabled
+)

libcontainer/configs/validate/intelrdt_test.go

@@ -4,12 +4,10 @@ import (
 	"testing"
 
 	"github.com/opencontainers/runc/libcontainer/configs"
+	"github.com/opencontainers/runc/libcontainer/intelrdt"
 )
 
 func TestValidateIntelRdt(t *testing.T) {
-	// Call init to trigger the sync.Once and enable overriding the rdt status
-	intelRdt.init()
-
 	testCases := []struct {
 		name       string
 		rdtEnabled bool
@@ -90,11 +88,17 @@ func TestValidateIntelRdt(t *testing.T) {
 			},
 		},
 	}
+
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			intelRdt.rdtEnabled = tc.rdtEnabled
-			intelRdt.catEnabled = tc.catEnabled
-			intelRdt.mbaEnabled = tc.mbaEnabled
+			t.Cleanup(func() {
+				intelRdtIsEnabled = intelrdt.IsEnabled
+				intelRdtIsCATEnabled = intelrdt.IsCATEnabled
+				intelRdtIsMBAEnabled = intelrdt.IsMBAEnabled
+			})
+			intelRdtIsEnabled = func() bool { return tc.rdtEnabled }
+			intelRdtIsCATEnabled = func() bool { return tc.catEnabled }
+			intelRdtIsMBAEnabled = func() bool { return tc.mbaEnabled }
 
 			config := &configs.Config{
 				Rootfs:   "/var",

libcontainer/configs/validate/validator.go

@@ -309,7 +309,7 @@ func intelrdtCheck(config *configs.Config) error {
 	if config.IntelRdt == nil {
 		return nil
 	}
-	if !intelRdt.isEnabled() {
+	if !intelRdtIsEnabled() {
 		return fmt.Errorf("intelRdt is specified in config, but Intel RDT is not enabled")
 	}
 
@@ -317,11 +317,10 @@ func intelrdtCheck(config *configs.Config) error {
 	case clos == ".", clos == "..", len(clos) > 1 && strings.Contains(clos, "/"):
 		return fmt.Errorf("invalid intelRdt.ClosID %q", clos)
 	}
-
-	if !intelRdt.isCATEnabled() && config.IntelRdt.L3CacheSchema != "" {
+	if !intelRdtIsCATEnabled() && config.IntelRdt.L3CacheSchema != "" {
 		return errors.New("intelRdt.l3CacheSchema is specified in config, but Intel RDT/CAT is not enabled")
 	}
-	if !intelRdt.isMBAEnabled() && config.IntelRdt.MemBwSchema != "" {
+	if !intelRdtIsMBAEnabled() && config.IntelRdt.MemBwSchema != "" {
 		return errors.New("intelRdt.memBwSchema is specified in config, but Intel RDT/MBA is not enabled")
 	}