fix communicator's c_lock usage

- initialize c_lock in the ompi_communicator_t constructor
 - USE_OPAL_THREAD_[UN]LOCK(c_lock)
 - #ifdef USE_MUTEX_FOR_COMMS protect c_lock access

Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>

ompi/communicator/comm_init.c

@@ -387,6 +387,9 @@ static void ompi_comm_construct(ompi_communicator_t* comm)
 #ifdef OMPI_WANT_PERUSE
     comm->c_peruse_handles = NULL;
 #endif
+#ifdef USE_MUTEX_FOR_COMMS
+    OBJ_CONSTRUCT(&comm->c_lock, opal_mutex_t);
+#endif
 }
 
 static void ompi_comm_destruct(ompi_communicator_t* comm)

ompi/mpi/c/comm_get_errhandler.c

@@ -11,7 +11,7 @@
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
  * Copyright (c) 2007-2009 Cisco Systems, Inc.  All rights reserved.
- * Copyright (c) 2015      Research Organization for Information Science
+ * Copyright (c) 2015-2017 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * Copyright (c) 2016-2017 Los Alamos National Security, LLC. All rights
  *                         reserved.
@@ -63,12 +63,16 @@ int MPI_Comm_get_errhandler(MPI_Comm comm, MPI_Errhandler *errhandler)
     }
   }
 
-  opal_mutex_lock (&comm->c_lock);
+#ifdef USE_MUTEX_FOR_COMMS
+    OPAL_THREAD_LOCK(&(comm->c_lock));
+#endif
   /* Retain the errhandler, corresponding to object refcount decrease
      in errhandler_free.c. */
   OBJ_RETAIN(comm->error_handler);
   *errhandler = comm->error_handler;
-  opal_mutex_unlock (&comm->c_lock);
+#ifdef USE_MUTEX_FOR_COMMS
+    OPAL_THREAD_UNLOCK(&(comm->c_lock));
+#endif
 
   /* All done */
 

ompi/mpi/c/comm_set_errhandler.c

@@ -10,7 +10,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
- * Copyright (c) 2015      Research Organization for Information Science
+ * Copyright (c) 2015-2017 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * Copyright (c) 2016-2017 Los Alamos National Security, LLC. All rights
  *                         reserved.
@@ -69,12 +69,16 @@ int MPI_Comm_set_errhandler(MPI_Comm comm, MPI_Errhandler errhandler)
     /* Prepare the new error handler */
     OBJ_RETAIN(errhandler);
 
-    opal_mutex_lock (&comm->c_lock);
+#ifdef USE_MUTEX_FOR_COMMS
+    OPAL_THREAD_LOCK(&(comm->c_lock));
+#endif
     /* Ditch the old errhandler, and decrement its refcount. */
     tmp = comm->error_handler;
     comm->error_handler = errhandler;
     OBJ_RELEASE(tmp);
-    opal_mutex_unlock (&comm->c_lock);
+#ifdef USE_MUTEX_FOR_COMMS
+    OPAL_THREAD_UNLOCK(&(comm->c_lock));
+#endif
 
     /* All done */
     return MPI_SUCCESS;