static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
			       int addr_len, int flags)
{
	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
	struct sock *sk = sock->sk;
	struct net *net = sock_net(sk);
	struct unix_sock *u = unix_sk(sk), *newu, *otheru;
	struct sock *newsk = NULL;
	struct sock *other = NULL;
	struct sk_buff *skb = NULL;
	unsigned int hash;
	int st;
	int err;
	long timeo;

	err = unix_mkname(sunaddr, addr_len, &hash);
	if (err < 0)
		goto out;
	addr_len = err;

	if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr &&
	    (err = unix_autobind(sock)) != 0)
		goto out;

	timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);

	/* First of all allocate resources.
	   If we will make it after state is locked,
	   we will have to recheck all again in any case.
	 */

	err = -ENOMEM;

	/* create new sock for complete connection */
	newsk = unix_create1(sock_net(sk), NULL, 0);
	if (newsk == NULL)
		goto out;

	/* Allocate skb for sending to listening sock */
	skb = sock_wmalloc(newsk, 1, 0, GFP_KERNEL);
	if (skb == NULL)
		goto out;

restart:
	/*  Find listening sock. */
	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
	if (!other)
		goto out;

	/* Latch state of peer */
	unix_state_lock(other);

	/* Apparently VFS overslept socket death. Retry. */
	if (sock_flag(other, SOCK_DEAD)) {
		unix_state_unlock(other);
		sock_put(other);
		goto restart;
	}

	err = -ECONNREFUSED;
	if (other->sk_state != TCP_LISTEN)
		goto out_unlock;
	if (other->sk_shutdown & RCV_SHUTDOWN)
		goto out_unlock;

	if (unix_recvq_full(other)) {
		err = -EAGAIN;
		if (!timeo)
			goto out_unlock;

		timeo = unix_wait_for_peer(other, timeo);

		err = sock_intr_errno(timeo);
		if (signal_pending(current))
			goto out;
		sock_put(other);
		goto restart;
	}

	/* Latch our state.

	   It is tricky place. We need to grab our state lock and cannot
	   drop lock on peer. It is dangerous because deadlock is
	   possible. Connect to self case and simultaneous
	   attempt to connect are eliminated by checking socket
	   state. other is TCP_LISTEN, if sk is TCP_LISTEN we
	   check this before attempt to grab lock.

	   Well, and we have to recheck the state after socket locked.
	 */
	st = sk->sk_state;

	switch (st) {
	case TCP_CLOSE:
		/* This is ok... continue with connect */
		break;
	case TCP_ESTABLISHED:
		/* Socket is already connected */
		err = -EISCONN;
		goto out_unlock;
	default:
		err = -EINVAL;
		goto out_unlock;
	}

	unix_state_lock_nested(sk);

	if (sk->sk_state != st) {
		unix_state_unlock(sk);
		unix_state_unlock(other);
		sock_put(other);
		goto restart;
	}

	err = security_unix_stream_connect(sk, other, newsk);
	if (err) {
		unix_state_unlock(sk);
		goto out_unlock;
	}

	/* The way is open! Fastly set all the necessary fields... */

	sock_hold(sk);
	unix_peer(newsk)	= sk;
	newsk->sk_state		= TCP_ESTABLISHED;
	newsk->sk_type		= sk->sk_type;
	init_peercred(newsk);
	newu = unix_sk(newsk);
	RCU_INIT_POINTER(newsk->sk_wq, &newu->peer_wq);
	otheru = unix_sk(other);

	/* copy address information from listening to new sock
	 *
	 * The contents of *(otheru->addr) and otheru->path
	 * are seen fully set up here, since we have found
	 * otheru in hash under unix_table_lock.  Insertion
	 * into the hash chain we'd found it in had been done
	 * in an earlier critical area protected by unix_table_lock,
	 * the same one where we'd set *(otheru->addr) contents,
	 * as well as otheru->path and otheru->addr itself.
	 *
	 * Using smp_store_release() here to set newu->addr
	 * is enough to make those stores, as well as stores
	 * to newu->path visible to anyone who gets newu->addr
	 * by smp_load_acquire().  IOW, the same warranties
	 * as for unix_sock instances bound in unix_bind() or
	 * in unix_autobind().
	 */
	if (otheru->path.dentry) {
		path_get(&otheru->path);
		newu->path = otheru->path;
	}
	refcount_inc(&otheru->addr->refcnt);
	smp_store_release(&newu->addr, otheru->addr);

	/* Set credentials */
	copy_peercred(sk, other);

	sock->state	= SS_CONNECTED;
	sk->sk_state	= TCP_ESTABLISHED;
	sock_hold(newsk);

	smp_mb__after_atomic();	/* sock_hold() does an atomic_inc() */
	unix_peer(sk)	= newsk;

	unix_state_unlock(sk);

	/* take ten and send info to listening sock */
	spin_lock(&other->sk_receive_queue.lock);
	__skb_queue_tail(&other->sk_receive_queue, skb);
	spin_unlock(&other->sk_receive_queue.lock);
	unix_state_unlock(other);
	other->sk_data_ready(other);
	sock_put(other);
	return 0;

out_unlock:
	if (other)
		unix_state_unlock(other);

out:
	kfree_skb(skb);
	if (newsk)
		unix_release_sock(newsk, 0);
	if (other)
		sock_put(other);
	return err;
}
static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
			       int addr_len, int flags)
{
	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
	struct sock *sk = sock->sk;
	struct net *net = sock_net(sk);
	struct unix_sock *u = unix_sk(sk), *newu, *otheru;
	struct sock *newsk = NULL;
	struct sock *other = NULL;
	struct sk_buff *skb = NULL;
	unsigned int hash;
	int st;
	int err;
	long timeo;

	err = unix_mkname(sunaddr, addr_len, &hash);
	if (err < 0)
		goto out;
	addr_len = err;

	if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr &&
	    (err = unix_autobind(sock)) != 0)
		goto out;

	timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);

	 

	err = -ENOMEM;

	 
	newsk = unix_create1(sock_net(sk), NULL, 0);
	if (newsk == NULL)
		goto out;

	 
	skb = sock_wmalloc(newsk, 1, 0, GFP_KERNEL);
	if (skb == NULL)
		goto out;

restart:
	 
	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
	if (!other)
		goto out;

	 
	unix_state_lock(other);

	 
	if (sock_flag(other, SOCK_DEAD)) {
		unix_state_unlock(other);
		sock_put(other);
		goto restart;
	}

	err = -ECONNREFUSED;
	if (other->sk_state != TCP_LISTEN)
		goto out_unlock;
	if (other->sk_shutdown & RCV_SHUTDOWN)
		goto out_unlock;

	if (unix_recvq_full(other)) {
		err = -EAGAIN;
		if (!timeo)
			goto out_unlock;

		timeo = unix_wait_for_peer(other, timeo);

		err = sock_intr_errno(timeo);
		if (signal_pending(current))
			goto out;
		sock_put(other);
		goto restart;
	}

	 
	st = sk->sk_state;

	switch (st) {
	case TCP_CLOSE:
		 
		break;
	case TCP_ESTABLISHED:
		 
		err = -EISCONN;
		goto out_unlock;
	default:
		err = -EINVAL;
		goto out_unlock;
	}

	unix_state_lock_nested(sk);

	if (sk->sk_state != st) {
		unix_state_unlock(sk);
		unix_state_unlock(other);
		sock_put(other);
		goto restart;
	}

	err = security_unix_stream_connect(sk, other, newsk);
	if (err) {
		unix_state_unlock(sk);
		goto out_unlock;
	}

	 

	sock_hold(sk);
	unix_peer(newsk)	= sk;
	newsk->sk_state		= TCP_ESTABLISHED;
	newsk->sk_type		= sk->sk_type;
	init_peercred(newsk);
	newu = unix_sk(newsk);
	RCU_INIT_POINTER(newsk->sk_wq, &newu->peer_wq);
	otheru = unix_sk(other);

	 
	if (otheru->path.dentry) {
		path_get(&otheru->path);
		newu->path = otheru->path;
	}
	refcount_inc(&otheru->addr->refcnt);
	smp_store_release(&newu->addr, otheru->addr);

	 
	copy_peercred(sk, other);

	sock->state	= SS_CONNECTED;
	sk->sk_state	= TCP_ESTABLISHED;
	sock_hold(newsk);

	smp_mb__after_atomic();	 
	unix_peer(sk)	= newsk;

	unix_state_unlock(sk);

	 
	spin_lock(&other->sk_receive_queue.lock);
	__skb_queue_tail(&other->sk_receive_queue, skb);
	spin_unlock(&other->sk_receive_queue.lock);
	unix_state_unlock(other);
	other->sk_data_ready(other);
	sock_put(other);
	return 0;

out_unlock:
	if (other)
		unix_state_unlock(other);

out:
	kfree_skb(skb);
	if (newsk)
		unix_release_sock(newsk, 0);
	if (other)
		sock_put(other);
	return err;
}