af_vsock: separate receive data loop

Some code in receive data loop could be shared between SEQPACKET
and STREAM sockets, while another part is type specific, so move STREAM
specific data receive logic to '__vsock_stream_recvmsg()' dedicated
function, while checks, that will be same for both STREAM and SEQPACKET
sockets, stays in 'vsock_connectible_recvmsg()'.

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/vmw_vsock/af_vsock.c

@@ -1896,65 +1896,22 @@ static int vsock_wait_data(struct sock *sk, struct wait_queue_entry *wait,
 	return data;
 }
 
-static int
+static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,
-vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
+				  size_t len, int flags)
-			  int flags)
 {
-	struct sock *sk;
-	struct vsock_sock *vsk;
-	const struct vsock_transport *transport;
-	int err;
-	size_t target;
-	ssize_t copied;
-	long timeout;
 	struct vsock_transport_recv_notify_data recv_data;
+	const struct vsock_transport *transport;
+	struct vsock_sock *vsk;
+	ssize_t copied;
+	size_t target;
+	long timeout;
+	int err;
 
 	DEFINE_WAIT(wait);
 
-	sk = sock->sk;
 	vsk = vsock_sk(sk);
-	err = 0;
-
-	lock_sock(sk);
-
 	transport = vsk->transport;
 
-	if (!transport || sk->sk_state != TCP_ESTABLISHED) {
-		/* Recvmsg is supposed to return 0 if a peer performs an
-		 * orderly shutdown. Differentiate between that case and when a
-		 * peer has not connected or a local shutdown occurred with the
-		 * SOCK_DONE flag.
-		 */
-		if (sock_flag(sk, SOCK_DONE))
-			err = 0;
-		else
-			err = -ENOTCONN;
-
-		goto out;
-	}
-
-	if (flags & MSG_OOB) {
-		err = -EOPNOTSUPP;
-		goto out;
-	}
-
-	/* We don't check peer_shutdown flag here since peer may actually shut
-	 * down, but there can be data in the queue that a local socket can
-	 * receive.
-	 */
-	if (sk->sk_shutdown & RCV_SHUTDOWN) {
-		err = 0;
-		goto out;
-	}
-
-	/* It is valid on Linux to pass in a zero-length receive buffer.  This
-	 * is not an error.  We may as well bail out now.
-	 */
-	if (!len) {
-		err = 0;
-		goto out;
-	}
-
 	/* We must not copy less than target bytes into the user's buffer
 	 * before returning successfully, so we wait for the consume queue to
 	 * have that much data to consume before dequeueing.  Note that this
@@ -2013,6 +1970,67 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 	if (copied > 0)
 		err = copied;
 
+out:
+	return err;
+}
+
+static int
+vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
+			  int flags)
+{
+	struct sock *sk;
+	struct vsock_sock *vsk;
+	const struct vsock_transport *transport;
+	int err;
+
+	DEFINE_WAIT(wait);
+
+	sk = sock->sk;
+	vsk = vsock_sk(sk);
+	err = 0;
+
+	lock_sock(sk);
+
+	transport = vsk->transport;
+
+	if (!transport || sk->sk_state != TCP_ESTABLISHED) {
+		/* Recvmsg is supposed to return 0 if a peer performs an
+		 * orderly shutdown. Differentiate between that case and when a
+		 * peer has not connected or a local shutdown occurred with the
+		 * SOCK_DONE flag.
+		 */
+		if (sock_flag(sk, SOCK_DONE))
+			err = 0;
+		else
+			err = -ENOTCONN;
+
+		goto out;
+	}
+
+	if (flags & MSG_OOB) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	/* We don't check peer_shutdown flag here since peer may actually shut
+	 * down, but there can be data in the queue that a local socket can
+	 * receive.
+	 */
+	if (sk->sk_shutdown & RCV_SHUTDOWN) {
+		err = 0;
+		goto out;
+	}
+
+	/* It is valid on Linux to pass in a zero-length receive buffer.  This
+	 * is not an error.  We may as well bail out now.
+	 */
+	if (!len) {
+		err = 0;
+		goto out;
+	}
+
+	err = __vsock_stream_recvmsg(sk, msg, len, flags);
+
 out:
 	release_sock(sk);
 	return err;