Avoid atomic operation if all requests have completed

Signed-off-by: Joseph Schuchart <schuchart@icl.utk.edu>

Author: devreal

ompi/mpiext/continue/c/continuation.c

@@ -884,7 +884,12 @@ int ompi_continue_attach(
     assert(count >= num_registered);
     int num_complete = count - num_registered;
     int32_t last_num_active = count;
-    if (num_complete > 0) {
+    if (0 == num_registered) {
+        /* all requests were complete */
+        cont->cont_num_active = 0;
+        last_num_active = 0;
+    } else if (num_complete > 0) {
+        /* some requests were complete */
         last_num_active = OPAL_THREAD_ADD_FETCH32(&cont->cont_num_active, -num_complete);
     }
     if (0 == last_num_active) {