netlink_bind
if (nlk->netlink_bind && groups) {
err = nlk->netlink_bind(net, group + 1);
if (optname == NETLINK_ADD_MEMBERSHIP && nlk->netlink_bind) {
err = nlk->netlink_bind(sock_net(sk), val);
.bind = netlink_bind,
nlk->netlink_bind = bind;
int (*netlink_bind)(struct net *net, int group);