diff --git a/internal/upgrade/upgrader.go b/internal/upgrade/upgrader.go
index 7f213ba5ec9b94b8d5a932b1ff3b5f09bfaac608..d818fe686934c4d9b38b8d28673319aa58daa3f4 100644
--- a/internal/upgrade/upgrader.go
+++ b/internal/upgrade/upgrader.go
@@ -13,7 +13,6 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"sync"
 	"sync/atomic"
 	"time"
 
@@ -330,26 +329,3 @@ func UnmarshalReport(b []byte) (Report, error) {
 	}
 	return r, nil
 }
-
-// atomicFlag 是对 sync.Mutex 的极小封装，与 task-manager 端"同时只
-// 允许一个部署"的模式保持对称。导出以备 Stage 5 的文件拉取升级器复用。
-type atomicFlag struct {
-	mu sync.Mutex
-	on bool
-}
-
-func (a *atomicFlag) tryLock() bool {
-	a.mu.Lock()
-	defer a.mu.Unlock()
-	if a.on {
-		return false
-	}
-	a.on = true
-	return true
-}
-
-func (a *atomicFlag) unlock() {
-	a.mu.Lock()
-	a.on = false
-	a.mu.Unlock()
-}