pnextrframe = LIST_CONTAINOR(plist, union recv_frame, u);
pnextattrib = &pnextrframe->u.hdr.attrib;
if (SN_LESS(pnextattrib->seq_num, pattrib->seq_num))
pnextrframe = LIST_CONTAINOR(plist, union recv_frame, u);
pnextattrib = &pnextrframe->u.hdr.attrib;
if (SN_LESS(pnextattrib->seq_num, pattrib->seq_num))