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

Sebastian Huber sebastian.huber at embedded-brains.de
Fri Apr 16 06:59:00 UTC 2021

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.
     There was no semaphore associated with the identifier specified by ``id``.
+    The semaphore uses a priority ceiling and there was no priority ceiling
+    defined for the :term:`home scheduler` of the calling task.
     The semaphore could not be obtained immediately.
+    The semaphore uses a priority ceiling and the calling task had a current
+    priority less than the priority ceiling.
     Acquiring of the local, binary semaphore by the calling task would have
     cased a deadlock.

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