fix: race condition in lockMap

(cherry picked from commit afc4cb3)

pkg/provider/azure_utils.go

@@ -56,35 +56,25 @@ func newLockMap() *lockMap {
 func (lm *lockMap) LockEntry(entry string) {
 	lm.Lock()
 	// check if entry does not exists, then add entry
-	if _, exists := lm.mutexMap[entry]; !exists {
-		lm.addEntry(entry)
+	mutex, exists := lm.mutexMap[entry]
+	if !exists {
+		mutex = &sync.Mutex{}
+		lm.mutexMap[entry] = mutex
 	}
-
 	lm.Unlock()
-	lm.lockEntry(entry)
+	mutex.Lock()
 }
 
 // UnlockEntry release the lock associated with the specific entry
 func (lm *lockMap) UnlockEntry(entry string) {
 	lm.Lock()
 	defer lm.Unlock()
 
-	if _, exists := lm.mutexMap[entry]; !exists {
+	mutex, exists := lm.mutexMap[entry]
+	if !exists {
 		return
 	}
-	lm.unlockEntry(entry)
-}
-
-func (lm *lockMap) addEntry(entry string) {
-	lm.mutexMap[entry] = &sync.Mutex{}
-}
-
-func (lm *lockMap) lockEntry(entry string) {
-	lm.mutexMap[entry].Lock()
-}
-
-func (lm *lockMap) unlockEntry(entry string) {
-	lm.mutexMap[entry].Unlock()
+	mutex.Unlock()
 }
 
 func getContextWithCancel() (context.Context, context.CancelFunc) {

pkg/provider/azure_vmss_test.go

@@ -2636,6 +2636,13 @@ func TestEnsureBackendPoolDeleted(t *testing.T) {
 	}
 }
 
+func TestEnsureBackendPoolDeletedConcurrentlyLoop(t *testing.T) {
+	// run TestEnsureBackendPoolDeletedConcurrently 20 times to detect race conditions
+	for i := 0; i < 20; i++ {
+		TestEnsureBackendPoolDeletedConcurrently(t)
+	}
+}
+
 func TestEnsureBackendPoolDeletedConcurrently(t *testing.T) {
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()