sev_pos
kev = sev->events + sev_pos(sev, 0);
sev->first = sev_pos(sev, 1);
sev->events + sev_pos(sev, 0);
kev = sev->events + sev_pos(sev, sev->in_use);
list_del(&sev->events[sev_pos(sev, i)].list);
kev->sev->first = sev_pos(kev->sev, 1);