pl_enter_try
return pp->pr_lock_ops->pl_enter_try(pl);
!pl_enter_try(pp, &pp->pr_lock)) /* try */
if (pl_enter_try(pp, &pp->pr_cache_lock) == 0) {
pl_enter_try(pp, &pp->pr_cache_lock)) {
int (*pl_enter_try)(union pool_lock *);