rcu_bp_register(); /* If not yet registered. */
cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
tmp = URCU_TLS(rcu_reader)->ctr;
+ urcu_assert((tmp & RCU_GP_CTR_NEST_MASK) != RCU_GP_CTR_NEST_MASK);
_rcu_read_lock_update(tmp);
}