diff --git a/backend/destination.go b/backend/destination.go
index 76ad6e4..44f4288 100644
--- a/backend/destination.go
+++ b/backend/destination.go
@@ -57,6 +57,7 @@ func CheckOfflineDestinations(nowTimeStamp int64) {
 					utils.DebugPrintln("Unmarshal K8S API", err)
 				}
 				dest.Mutex.Lock()
+				defer dest.Mutex.Unlock()
 				dest.Pods = ""
 				for _, podItem := range pods.Items {
 					if podItem.Status.Phase == "Running" {
@@ -68,7 +69,6 @@ func CheckOfflineDestinations(nowTimeStamp int64) {
 				}
 				dest.CheckTime = nowTimeStamp
 				dest.Online = true
-				dest.Mutex.Unlock()
 			}
 		}
 	}
diff --git a/backend/k8s.go b/backend/k8s.go
index 91d5bcf..b52f51d 100644
--- a/backend/k8s.go
+++ b/backend/k8s.go
@@ -20,6 +20,7 @@ import (
 func UpdatePods(dest *models.Destination, nowTimeStamp int64) {
 	dest.IsUpdating = true
 	dest.Mutex.Lock() // write lock
+	defer dest.Mutex.Unlock()
 	request, _ := http.NewRequest("GET", dest.PodsAPI, nil)
 	request.Header.Set("Content-Type", "application/json")
 	resp, err := utils.GetResponse(request)
@@ -42,7 +43,6 @@ func UpdatePods(dest *models.Destination, nowTimeStamp int64) {
 			dest.Pods += podItem.Status.PodIP + ":" + dest.PodPort
 		}
 	}
-	dest.Mutex.Unlock()
 	dest.IsUpdating = false
 }
 
diff --git a/firewall/cc.go b/firewall/cc.go
index 787783e..3408e94 100644
--- a/firewall/cc.go
+++ b/firewall/cc.go
@@ -54,6 +54,7 @@ func CCAttackTick(appID int64) {
 			stat := value.(*models.ClientStat)
 			//fmt.Println("CCAttackTick:", appID, clientID, stat)
 			stat.Mutex.Lock()
+			defer stat.Mutex.Unlock()
 			if stat.IsBadIP {
 				stat.RemainSeconds -= ccPolicy.IntervalMilliSeconds / 1000.0
 				if stat.RemainSeconds <= 0 {
@@ -84,7 +85,6 @@ func CCAttackTick(appID int64) {
 			}
 			stat.SlowCount += stat.QuickCount
 			stat.QuickCount = 0
-			stat.Mutex.Unlock()
 			return true
 		})
 	}
diff --git a/gateway/gateway.go b/gateway/gateway.go
index 69cba41..fc8c3c0 100644
--- a/gateway/gateway.go
+++ b/gateway/gateway.go
@@ -389,8 +389,8 @@ func ReverseHandlerFunc(w http.ResponseWriter, r *http.Request) {
 			dest.CheckTime = nowTimeStamp
 			if err != nil {
 				dest.Mutex.Lock()
+				defer dest.Mutex.Unlock()
 				dest.Online = false
-				dest.Mutex.Unlock()
 				utils.DebugPrintln("DialContext error", err)
 				if data.NodeSetting.SMTP.SMTPEnabled {
 					sendOfflineNotification(app, targetDest)