1 files changed, 4 insertions, 7 deletions
diff --git a/include/rtdef.h b/include/rtdef.h
index c37f90be2d..7889412ab3 100644
--- a/include/rtdef.h
+++ b/include/rtdef.h
@@ -496,10 +496,6 @@ typedef siginfo_t rt_siginfo_t;
 #define RT_THREAD_CTRL_CHANGE_PRIORITY  0x02                /**< Change thread priority. */
 #define RT_THREAD_CTRL_INFO             0x03                /**< Get thread information. */
 
-#ifdef RT_USING_LWP
-struct rt_lwp;
-#endif
-
 /**
  * Thread structure
  */
@@ -560,11 +556,12 @@ struct rt_thread
 
     void (*cleanup)(struct rt_thread *tid);             /**< cleanup function when thread exit */
 
-    rt_uint32_t user_data;                             /**< private user data beyond this thread */
-
+    /* light weight process if present */
 #ifdef RT_USING_LWP
-    struct rt_lwp *lwp;    /**< if NULL it's a kernel thread */
+    void        *lwp;
 #endif
+
+    rt_uint32_t user_data;                             /**< private user data beyond this thread */
 };
 typedef struct rt_thread *rt_thread_t;