sack_filter_blks
new_sb = sack_filter_blks(tp, &bbr->r_ctl.bbr_sf, sack_blocks,
sack_filter_blks(tp, &rack->r_ctl.rack_sf, NULL, 0, th_ack);
num_sack_blks = sack_filter_blks(tp, &rack->r_ctl.rack_sf, sack_blocks,
nn = sack_filter_blks(&tp, &sf, blks, numblks, th_ack);
sack_filter_blks(&tp, &sf, NULL, 0, th_ack);
int sack_filter_blks(struct tcpcb *tp, struct sack_filter *sf, struct sackblk *in, int numblks,