1 files changed, 61 insertions, 0 deletions
diff --git a/REORG.TODO/nptl/pthread_barrier_destroy.c b/REORG.TODO/nptl/pthread_barrier_destroy.c
new file mode 100644
index 0000000000..e79232bd8f
--- /dev/null
+++ b/REORG.TODO/nptl/pthread_barrier_destroy.c
@@ -0,0 +1,61 @@
+/* Copyright (C) 2002-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include "pthreadP.h"
+#include <atomic.h>
+#include <futex-internal.h>
+
+
+int
+pthread_barrier_destroy (pthread_barrier_t *barrier)
+{
+  struct pthread_barrier *bar = (struct pthread_barrier *) barrier;
+
+  /* Destroying a barrier is only allowed if no thread is blocked on it.
+     Thus, there is no unfinished round, and all modifications to IN will
+     have happened before us (either because the calling thread took part
+     in the most recent round and thus synchronized-with all other threads
+     entering, or the program ensured this through other synchronization).
+     We must wait until all threads that entered so far have confirmed that
+     they have exited as well.  To get the notification, pretend that we have
+     reached the reset threshold.  */
+  unsigned int count = bar->count;
+  unsigned int max_in_before_reset = BARRIER_IN_THRESHOLD
+				   - BARRIER_IN_THRESHOLD % count;
+  /* Relaxed MO sufficient because the program must have ensured that all
+     modifications happen-before this load (see above).  */
+  unsigned int in = atomic_load_relaxed (&bar->in);
+  /* Trigger reset.  The required acquire MO is below.  */
+  if (atomic_fetch_add_relaxed (&bar->out, max_in_before_reset - in) < in)
+    {
+      /* Not all threads confirmed yet that they have exited, so another
+	 thread will perform a reset.  Wait until that has happened.  */
+      while (in != 0)
+	{
+	  futex_wait_simple (&bar->in, in, bar->shared);
+	  in = atomic_load_relaxed (&bar->in);
+	}
+    }
+  /* We must ensure that memory reuse happens after all prior use of the
+     barrier (specifically, synchronize-with the reset of the barrier or the
+     confirmation of threads leaving the barrier).  */
+  atomic_thread_fence_acquire ();
+
+  return 0;
+}