next_child
struct proc *p, *child, *next_child, *old_parent, *new_parent;
for (; child != NULL; child = next_child) {
next_child = LIST_NEXT(child, p_sibling);
if (!next_child(>, &st, grp, src, mask, &vifi))
|| !next_child(>, &st, grp, src, mask, &vifi))