From 92745e6249cdbc43c78ae2e7376b36c541268542 Mon Sep 17 00:00:00 2001
From: bangerth <bangerth@0785d39b-7218-0410-832d-ea1e28bc413d>
Date: Thu, 3 Oct 2013 23:52:35 +0000
Subject: [PATCH] Work around a POSIX violation.

git-svn-id: https://svn.dealii.org/branches/branch_port_the_testsuite@31114 0785d39b-7218-0410-832d-ea1e28bc413d
---
 tests/base/thread_validity_09.cc | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/tests/base/thread_validity_09.cc b/tests/base/thread_validity_09.cc
index 3daddafba0..60d3247d9c 100644
--- a/tests/base/thread_validity_09.cc
+++ b/tests/base/thread_validity_09.cc
@@ -34,9 +34,15 @@ int spin_lock = 0;
 
 int worker ()
 {
+  // wait till the main thread has actually done its work -- we will
+  // hang in the 'acquire' line until the main thread releases the
+  // mutex. release the mutex again at the end of this function since
+  // mutices can only be relased on the same thread as they are
+  // acquired on.
   mutex.acquire ();
   deallog << "OK." << std::endl;
   spin_lock = 1;
+  mutex.release ();
   return 42;
 }
 
@@ -60,11 +66,12 @@ int main()
   for (unsigned int i=0; i<sz; ++i)
     p[i] = 0;
 
+  // make sure the worker thread can actually start
   mutex.release ();
 
+  // wait for the worker thread to do its work
   while (spin_lock == 0)
     ;
-  mutex.release ();
 
   for (unsigned int i=0; i<sz; ++i)
     Assert (p[i] == 0, ExcInternalError());
-- 
2.39.5