l2tp: simplify pppol2tp_ioctl()

* Drop test on 'sk': sock->sk cannot be NULL, or pppox_ioctl() could
    not have called us.

  * Drop test on 'SOCK_DEAD' state: if this flag was set, the socket
    would be in the process of being released and no ioctl could be
    running anymore.

  * Drop test on 'PPPOX_*' state: we depend on ->sk_user_data to get
    the session structure. If it is non-NULL, then the socket is
    connected. Testing for PPPOX_* is redundant.

  * Retrieve session using ->sk_user_data directly, instead of going
    through pppol2tp_sock_to_session(). This avoids grabbing a useless
    reference on the socket.
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_ppp.c

@@ -1179,28 +1179,12 @@ static int pppol2tp_tunnel_ioctl(struct l2tp_tunnel *tunnel,
 static int pppol2tp_ioctl(struct socket *sock, unsigned int cmd,
 			  unsigned long arg)
 {
-	struct sock *sk = sock->sk;
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel;
-	int err;
-
-	if (!sk)
-		return 0;
-
-	err = -EBADF;
-	if (sock_flag(sk, SOCK_DEAD) != 0)
-		goto end;
-
-	err = -ENOTCONN;
-	if ((sk->sk_user_data == NULL) ||
-	    (!(sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND))))
-		goto end;
 
-	/* Get session context from the socket */
-	err = -EBADF;
-	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
-		goto end;
+	session = sock->sk->sk_user_data;
+	if (!session)
+		return -ENOTCONN;
 
 	/* Special case: if session's session_id is zero, treat ioctl as a
 	 * tunnel ioctl
@@ -1208,16 +1192,11 @@ static int pppol2tp_ioctl(struct socket *sock, unsigned int cmd,
 	if ((session->session_id == 0) &&
 	    (session->peer_session_id == 0)) {
 		tunnel = session->tunnel;
-		err = pppol2tp_tunnel_ioctl(tunnel, cmd, arg);
-		goto end_put_sess;
-	}
 
-	err = pppol2tp_session_ioctl(session, cmd, arg);
+		return pppol2tp_tunnel_ioctl(tunnel, cmd, arg);
+	}
 
-end_put_sess:
-	sock_put(sk);
-end:
-	return err;
+	return pppol2tp_session_ioctl(session, cmd, arg);
 }
 
 /*****************************************************************************