SNOOP_DOWN
if (snp->snp_flags & SNOOP_DOWN) {
snp->snp_flags |= SNOOP_DOWN;
snp->snp_flags &= ~SNOOP_DOWN;
if (snp->snp_flags & SNOOP_DOWN) {
if (snp->snp_flags & SNOOP_DOWN || snp->snp_len > 0)