From: Gabriel Corona <gabriel.corona@loria.fr>
Date: Thu, 27 Mar 2014 10:00:11 +0000 (+0100)
Subject: [mc] Correctly handle the end of the stack unwinding
X-Git-Tag: v3_11~189^2~18
X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/commitdiff_plain/0f03f9b048ab31cdc19f07738e25264a9710d3dd

[mc] Correctly handle the end of the stack unwinding

unw_step returns 0 when reaching the bottom of the stack: this return
code was not handled correctly leading to infinite loops in some
cases.
---

diff --git a/src/mc/mc_checkpoint.c b/src/mc/mc_checkpoint.c
index cece2e82ad..e482c42aa4 100644
--- a/src/mc/mc_checkpoint.c
+++ b/src/mc/mc_checkpoint.c
@@ -323,8 +323,13 @@ static xbt_dynar_t MC_unwind_stack_frames(void *stack_context) {
 
   unw_cursor_t c;
 
-  int ret;
-  for(ret = unw_init_local(&c, (unw_context_t *)stack_context); ret >= 0; ret = unw_step(&c)){
+  // TODO, check condition check (unw_init_local==0 means end of frame)
+  if(unw_init_local(&c, (unw_context_t *)stack_context)!=0) {
+
+    xbt_die("Could not initialize stack unwinding");
+
+  } else while(1) {
+
     mc_stack_frame_t stack_frame = xbt_new(s_mc_stack_frame_t, 1);
     xbt_dynar_push(result, &stack_frame);
 
@@ -348,11 +353,19 @@ static xbt_dynar_t MC_unwind_stack_frames(void *stack_context) {
       stack_frame->frame_base = (unw_word_t)mc_find_frame_base(frame, frame->object_info, &c);
     } else {
       stack_frame->frame_base = 0;
+      stack_frame->frame_name = NULL;
     }
 
     /* Stop before context switch with maestro */
     if(frame!=NULL && frame->name!=NULL && !strcmp(frame->name, "smx_ctx_sysv_wrapper"))
       break;
+
+    int ret = ret = unw_step(&c);
+    if(ret==0) {
+      xbt_die("Unexpected end of stack.");
+    } else if(ret<0) {
+      xbt_die("Error while unwinding stack.");
+    }
   }
 
   if(xbt_dynar_length(result) == 0){