Clean up mutex issues.

    - Final fix for mutex bug.
    - Document weak-consistency decisions in mutex code.
    - Prevent aggressive optimizations around lwsync/isync instrs.
    - Fix minor bug in futex_wait system call.
    - Optimize futex path with likely/unlikely hints.

Change-Id: I26b54dee7e45bcb42195f730474b350b44f53cfc
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/233
Tested-by: Jenkins Server
Reviewed-by: A. Patrick Williams III <iawillia@us.ibm.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/usr/testcore/lib/synctest.H b/src/usr/testcore/lib/synctest.H
index 5a53d2e0a..8e7619d11 100644
--- a/src/usr/testcore/lib/synctest.H
+++ b/src/usr/testcore/lib/synctest.H
@@ -9,6 +9,7 @@
 #include <cxxtest/TestSuite.H>
 #include <sys/sync.h>
 #include <sys/task.h>
+#include <sys/time.h>
 
 class SyncTest: public CxxTest::TestSuite
 {
@@ -30,6 +31,20 @@ class SyncTest: public CxxTest::TestSuite
             TS_TRACE("ALL THREADS ENDED");
         }
 
+        void testMutexDoubleWait()
+        {
+            mutex_init(&mutex);
+            barrier_init(&barrier, 3);
+
+            mutex_lock(&mutex);
+            task_create(func2, this);
+            task_create(func2, this);
+            nanosleep(1,0);
+            mutex_unlock(&mutex);
+            barrier_wait(&barrier);
+            TS_TRACE("ALL THREADS ENDED");
+        }
+
         void testBarrier()
         {
             barrier_t barrier;