chgkqcnt
if (!chgkqcnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_KQUEUES)))
chgkqcnt(cred->cr_ruidinfo, -1, 0);
chgkqcnt(kq->kq_cred->cr_ruidinfo, -1, 0);
int chgkqcnt(struct uidinfo *uip, int diff, rlim_t max);