diff --git a/device/plugins/ftrace_plugin/src/flow_controller.cpp b/device/plugins/ftrace_plugin/src/flow_controller.cpp
index 83fe80baca5c06391d07503b90c17b3d32bcb428..aaa4f0042311756f4b3476473a1c692507dfbb93 100644
--- a/device/plugins/ftrace_plugin/src/flow_controller.cpp
+++ b/device/plugins/ftrace_plugin/src/flow_controller.cpp
@@ -370,7 +370,7 @@ long FlowController::HmReadEventData()
     long nbytes = 0;
     long used = 0;
     long rest = bufferSize;
-    while ((nbytes = reader->Read(&buffer[used], rest)) > 0 && used < bufferSize) {
+    while (used < bufferSize && (nbytes = reader->Read(&buffer[used], rest)) > 0) {
         used += nbytes;
         rest -= nbytes;
     }