[RFC PATCH v2 03/13] af_vsock: implement rx loops entry point

[Arseny Krasnov <arseny.krasnov@kaspersky.com>]

This adds entry point for STREAM/SEQPACKET rx loops. As both types are
connect oriented, so there are same checks before reading data from
socket. All this checks are performed in this entry point, then specific
rx loop is called.

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
 net/vmw_vsock/af_vsock.c | 55 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index afacbe9f4231..38afaa90d141 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -2244,6 +2244,61 @@ vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 	return err;
 }
 
+static int vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg,
+				     size_t len, int flags)
+{
+	struct sock *sk;
+	int err = 0;
+	struct vsock_sock *vsk;
+	const struct vsock_transport *transport;
+
+	sk = sock->sk;
+
+	lock_sock(sk);
+
+	vsk = vsock_sk(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 = -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)
+		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)
+		goto out;
+
+	if (sk->sk_type == SOCK_STREAM)
+		err = __vsock_stream_recvmsg(sk, msg, len, flags);
+	else
+		err = __vsock_seqpacket_recvmsg(sk, msg, len, flags);
+
+out:
+	release_sock(sk);
+	return err;
+}
+
 static const struct proto_ops vsock_stream_ops = {
 	.family = PF_VSOCK,
 	.owner = THIS_MODULE,
-- 
2.25.1