/* All threads should finish using the data referred to by old ptr
* before decrementing their urcu_active_readers count */
/* Finish waiting for reader threads before letting the old ptr being
* freed. */
force_mb_all_threads();
/* All threads should finish using the data referred to by old ptr
* before decrementing their urcu_active_readers count */
/* Finish waiting for reader threads before letting the old ptr being
* freed. */
force_mb_all_threads();