NFC: llcp: Fix non blocking sockets connections

Without the new LLCP_CONNECTING state, non blocking sockets will be
woken up with a POLLHUP right after calling connect() because their
state is stuck at LLCP_CLOSED.
That prevents userspace from implementing any proper non blocking
socket based NFC p2p client.

Cc: stable@vger.kernel.org
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

net/nfc/llcp.h

@@ -19,6 +19,7 @@
 
 enum llcp_state {
 	LLCP_CONNECTED = 1, /* wait_for_packet() wants that */
+	LLCP_CONNECTING,
 	LLCP_DISCONNECTING,
 	LLCP_CLOSED,
 	LLCP_BOUND,

net/nfc/llcp_sock.c

@@ -571,7 +571,7 @@ static unsigned int llcp_sock_poll(struct file *file, struct socket *sock,
 	if (sk->sk_shutdown == SHUTDOWN_MASK)
 		mask |= POLLHUP;
 
-	if (sock_writeable(sk))
+	if (sock_writeable(sk) && sk->sk_state == LLCP_CONNECTED)
 		mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
 	else
 		set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
@@ -729,14 +729,16 @@ static int llcp_sock_connect(struct socket *sock, struct sockaddr *_addr,
 	if (ret)
 		goto sock_unlink;
 
+	sk->sk_state = LLCP_CONNECTING;
+
 	ret = sock_wait_state(sk, LLCP_CONNECTED,
 			      sock_sndtimeo(sk, flags & O_NONBLOCK));
-	if (ret)
+	if (ret && ret != -EINPROGRESS)
 		goto sock_unlink;
 
 	release_sock(sk);
 
-	return 0;
+	return ret;
 
 sock_unlink:
 	nfc_llcp_put_ssap(local, llcp_sock->ssap);