#define read_free_race	(read_generation[0] == last_free_gen)
#define read_free	(free_done && data_access[0])

#define RCU_GP_CTR_BIT (1 << 7)
#define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_BIT - 1)

//FIXME
//#define REMOTE_BARRIERS