libmthread: do not dump stack for free threads

Change-Id: Ic438a252f5bddaf1513f554c71173e6fffb0c674

diff --git a/lib/libmthread/misc.c b/lib/libmthread/misc.c
index 86c8800acb74afa2b9ce162a5d0742a89d4a8983..51c99c8ab11f81d6dffff41a2aa871388760d50b 100644 (file)
--- a/lib/libmthread/misc.c
+++ b/lib/libmthread/misc.c
@@ -122,10 +122,14 @@ void mthread_stacktrace(mthread_thread_t t)
   mcontext_t *mtx;
   struct stackframe_s *frame;
 
-  printf("thread %d: ", t);
-
   tcb = mthread_find_tcb(t);
   ctx = &tcb->m_context;
+
+  if (t != MAIN_THREAD && ctx->uc_stack.ss_size == 0)
+       return; /* no stack, no stacktrace */
+
+  printf("thread %d: ", t);
+
   mtx = &ctx->uc_mcontext;
   frame = &mtx->mc_p_reg;
   bp = frame->fp;