Wait for criuProcess once

Signed-off-by: Ted Yu <yuzhihong@gmail.com>

libcontainer/container_linux.go

@@ -1504,11 +1504,14 @@ func (c *linuxContainer) criuSwrk(process *Process, req *criurpc.CriuReq, opts *
 	// cmd.Process will be replaced by a restored init.
 	criuProcess := cmd.Process
 
+	var st *os.ProcessState
 	defer func() {
-		criuClientCon.Close()
-		_, err := criuProcess.Wait()
-		if err != nil {
-			return
+		if st == nil {
+			criuClientCon.Close()
+			_, err := criuProcess.Wait()
+			if err != nil {
+				return
+			}
 		}
 	}()
 
@@ -1634,7 +1637,7 @@ func (c *linuxContainer) criuSwrk(process *Process, req *criurpc.CriuReq, opts *
 	criuClientCon.CloseWrite()
 	// cmd.Wait() waits cmd.goroutines which are used for proxying file descriptors.
 	// Here we want to wait only the CRIU process.
-	st, err := criuProcess.Wait()
+	st, err = criuProcess.Wait()
 	if err != nil {
 		return err
 	}