[PATCH] c-user: Document rtems_semaphore_obtain() errors

[Sebastian Huber]

Update #3993.
---
 c-user/semaphore/directives.rst | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/c-user/semaphore/directives.rst b/c-user/semaphore/directives.rst
index 54f40a4..7c2a9c8 100644
--- a/c-user/semaphore/directives.rst
+++ b/c-user/semaphore/directives.rst
@@ -525,9 +525,17 @@ scheduler.
 :c:macro:`RTEMS_INVALID_ID`
     There was no semaphore associated with the identifier specified by ``id``.
 
+:c:macro:`RTEMS_NOT_DEFINED`
+    The semaphore uses a priority ceiling and there was no priority ceiling
+    defined for the :term:`home scheduler` of the calling task.
+
 :c:macro:`RTEMS_UNSATISFIED`
     The semaphore could not be obtained immediately.
 
+:c:macro:`RTEMS_INVALID_PRIORITY`
+    The semaphore uses a priority ceiling and the calling task had a current
+    priority less than the priority ceiling.
+
 :c:macro:`RTEMS_INCORRECT_STATE`
     Acquiring of the local, binary semaphore by the calling task would have
     cased a deadlock.
-- 
2.26.2