From a246d6f1d13d1215e6556c5c419a7cb0e7afccab Mon Sep 17 00:00:00 2001
From: "Dr. Stefan Schimanski" <stefan.schimanski@gmail.com>
Date: Mon, 6 Nov 2017 18:31:40 +0100
Subject: [PATCH] apiserver: protect registry cleanup against concurrent access

---
 .../generic/registry/storage_factory.go       | 23 +++++++++++++++----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/staging/src/k8s.io/apiserver/pkg/registry/generic/registry/storage_factory.go b/staging/src/k8s.io/apiserver/pkg/registry/generic/registry/storage_factory.go
index 188f6f7bcdc..c1ef906f66d 100644
--- a/staging/src/k8s.io/apiserver/pkg/registry/generic/registry/storage_factory.go
+++ b/staging/src/k8s.io/apiserver/pkg/registry/generic/registry/storage_factory.go
@@ -17,6 +17,8 @@ limitations under the License.
 package registry
 
 import (
+	"sync"
+
 	"github.com/golang/glog"
 
 	"k8s.io/apimachinery/pkg/runtime"
@@ -82,13 +84,23 @@ func StorageWithCacher(capacity int) generic.StorageDecorator {
 // only from the test harness, so Register/Cleanup will be
 // no-op at runtime.
 
+var cleanupLock sync.Mutex
 var cleanup []func() = nil
 
 func TrackStorageCleanup() {
+	cleanupLock.Lock()
+	defer cleanupLock.Unlock()
+
+	if cleanup != nil {
+		panic("Conflicting storage tracking")
+	}
 	cleanup = make([]func(), 0)
 }
 
 func RegisterStorageCleanup(fn func()) {
+	cleanupLock.Lock()
+	defer cleanupLock.Unlock()
+
 	if cleanup == nil {
 		return
 	}
@@ -96,11 +108,12 @@ func RegisterStorageCleanup(fn func()) {
 }
 
 func CleanupStorage() {
-	if cleanup == nil {
-		return
-	}
-	for _, d := range cleanup {
+	cleanupLock.Lock()
+	old := cleanup
+	cleanup = nil
+	cleanupLock.Unlock()
+
+	for _, d := range old {
 		d()
 	}
-	cleanup = nil
 }