This issue is under review:
https://www.rtems.org/bugzilla/show_bug.cgi?id=1964

Doubly-linked lists ("chains") in RTEMS have a "control" block that
looks like the next/prev link pair in an element. The list elements
link both ways to this control block.

_Chain_Is_first and _Chain_Is_last only probed if the link to the
next element - which would be the control block - is non-NULL.
Telling by the function description and given that there are already
functions called _Chain_Is_head and _Chain_Is_tail (which could be
simplified), this is probably not the intended behaviour.

This also affects the aliases rtems_chain_is_first and
rtems_chain_is_last.

These functions are not used a lot and I haven't seen any immediate
effect on M1 after changing them, so I can't say whether this patch
may unearth other problems.

- Werner

Index: rtems/cpukit/score/inline/rtems/score/chain.inl
===================================================================
--- rtems.orig/cpukit/score/inline/rtems/score/chain.inl	2011-11-12 09:12:46.000000000 -0300
+++ rtems/cpukit/score/inline/rtems/score/chain.inl	2011-11-12 09:13:47.000000000 -0300
@@ -297,7 +297,7 @@
   const Chain_Node *the_node
 )
 {
-  return (the_node->previous == NULL);
+  return the_node->previous->previous == NULL;
 }
 
 /** @brief Is this the Last Node on the Chain
@@ -314,7 +314,7 @@
   const Chain_Node *the_node
 )
 {
-  return (the_node->next == NULL);
+  return the_node->next->next == NULL;
 }
 
 /** @brief Does this Chain have only One Node
