* __cds_wfs_pop_all does not require any synchronization with other
* push, nor with other __cds_wfs_pop_all, but requires synchronization
* matching the technique used to synchronize __cds_wfs_pop_blocking:
* __cds_wfs_pop_all does not require any synchronization with other
* push, nor with other __cds_wfs_pop_all, but requires synchronization
* matching the technique used to synchronize __cds_wfs_pop_blocking: