Merged revisions 198437 via svnmerge from

https://origsvn.digium.com/svn/asterisk/trunk

........
  r198437 | eliel | 2009-05-30 21:22:15 -0400 (Sat, 30 May 2009) | 11 lines
  
  Avoid a crash when res_timing_dahdi is unloaded but wasn't properly loaded.
  
  if dahdi_test_timer() fails, timing_funcs_handle remains NULL causing a crash
  when calling ast_unregister_timing_interface() with a NULL pointer.
  
  (closes issue #15234)
  Reported by: eliel
  Patches:
        timing_dahdi1.diff uploaded by eliel (license 64)
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.1@198441 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_timing_dahdi.c

@@ -192,7 +192,11 @@ static int load_module(void)
 
 static int unload_module(void)
 {
-	return ast_unregister_timing_interface(timing_funcs_handle);
+	if (timing_funcs_handle) {
+		return ast_unregister_timing_interface(timing_funcs_handle);
+	}
+
+	return 0;
 }
 
 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "DAHDI Timing Interface");