Remove heap allocation of xscom mutex.

Since mutexes are simply a uint64 with a static initializer, the xscom mutex
is now a instance variable directly in the cpu object.

Remove unneeded mutex_create function and changed the behavior of
mutex_destroy.

Change-Id: If6e1d1bf0083c32ef9e7502d27678811bdaf7e1e
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/150
Tested-by: Jenkins Server
Reviewed-by: Douglas R. Gilbert <dgilbert@us.ibm.com>
Reviewed-by: Thi N. Tran <thi@us.ibm.com>

2 files changed, 4 insertions, 33 deletions

diff --git a/src/lib/sync.C b/src/lib/sync.C
index a70761eef..093c7f41e 100644
--- a/src/lib/sync.C
+++ b/src/lib/sync.C
@@ -66,15 +66,6 @@ void barrier_wait (barrier_t * i_barrier)
 
 //-----------------------------------------------------------------------------
 
-mutex_t * mutex_create()
-{
-    mutex_t * m = new mutex_t;
-    mutex_init(m);
-    return m;
-}
-
-//-----------------------------------------------------------------------------
-
 void mutex_init(mutex_t * o_mutex)
 {
     o_mutex->iv_val = 0;
@@ -85,8 +76,7 @@ void mutex_init(mutex_t * o_mutex)
 
 void mutex_destroy(mutex_t *& i_mutex)
 {
-    delete i_mutex;
-    i_mutex = NULL;
+    i_mutex->iv_val = ~0;
     return;
 }
 
diff --git a/src/lib/syscall_mmio.C b/src/lib/syscall_mmio.C
index 91e4e113b..83a4f8f82 100644
--- a/src/lib/syscall_mmio.C
+++ b/src/lib/syscall_mmio.C
@@ -34,26 +34,7 @@ mutex_t * mmio_xscom_mutex()
 
     // Ensure task is pinned.
     assert(task->affinity_pinned);
-
-    // Get mutex from cpu structure.
-    mutex_t * mutex = task->cpu->xscom_mutex;
-
-    // Create mutex if not created.
-    if (NULL == mutex)
-    {
-        mutex = mutex_create();
-
-        // Atomically update xscom_mutex with new mutex.
-        if (!__sync_bool_compare_and_swap(&task->cpu->xscom_mutex, NULL, mutex))
-        {
-            // Failed, some other thread beat us to it.
-
-            // Destroy mutex and get one created by other thread in the
-            // meantime.
-            mutex_destroy(mutex);
-            mutex = task->cpu->xscom_mutex;
-        }
-    }
-
-    return mutex;
+    
+    // Return mutex from cpu structure.
+    return &task->cpu->xscom_mutex;
 }