Fix pthread_barrier_smoke test.

Bug: http://b/37652807
Test: run bionic-unit-tests.
Change-Id: Id7245223bc2a284efed6e710892b58947ef5d555
(cherry picked from commit d5c04c5ebb67e4581d7d861503de111ff84c5b75)

diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index 60fe294..54f2b13 100755 (executable)
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -1962,8 +1962,8 @@ static void BarrierTestHelper(BarrierTestHelperArg* arg) {
     } else {
       ASSERT_EQ(0, result);
     }
-    arg->data->finished_mask |= (1 << arg->id);
-    if (arg->data->finished_mask == ((1 << arg->data->thread_count) - 1)) {
+    int mask = arg->data->finished_mask.fetch_or(1 << arg->id);
+    if (mask == ((1 << arg->data->thread_count) - 1)) {
       ASSERT_EQ(1, arg->data->serial_thread_count);
       arg->data->finished_iteration_count++;
       arg->data->finished_mask = 0;