On 04.06.2021 18:06, Stefano Garzarella wrote:

On Thu, May 20, 2021 at 10:16:08PM +0300, Arseny Krasnov wrote:

quoted

Add receive loop for SEQPACKET. It looks like receive loop for
STREAM, but there are differences:
1) It doesn't call notify callbacks.
2) It doesn't care about 'SO_SNDLOWAT' and 'SO_RCVLOWAT' values, because
  there is no sense for these values in SEQPACKET case.
3) It waits until whole record is received or error is found during
  receiving.
4) It processes and sets 'MSG_TRUNC' flag.

So to avoid extra conditions for two types of socket inside one loop, two
independent functions were created.

Signed-off-by: Arseny Krasnov <redacted>
---
v9 -> v10:
1) Use 'msg_data_left()' instead of direct access to 'msg_hdr'.

include/net/af_vsock.h   |  4 +++
net/vmw_vsock/af_vsock.c | 72 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index b1c717286993..5175f5a52ce1 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h

@@ -135,6 +135,10 @@ struct vsock_transport {

	bool (*stream_is_active)(struct vsock_sock *);
	bool (*stream_allow)(u32 cid, u32 port);

+	/* SEQ_PACKET. */
+	ssize_t (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
+				     int flags, bool *msg_ready);
+
	/* Notification. */
	int (*notify_poll_in)(struct vsock_sock *, size_t, bool *);
	int (*notify_poll_out)(struct vsock_sock *, size_t, bool *);

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index c4f6bfa1e381..aede474343d1 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c

@@ -1974,6 +1974,73 @@ static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,

	return err;
}

+static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
+				     size_t len, int flags)
+{
+	const struct vsock_transport *transport;
+	bool msg_ready;
+	struct vsock_sock *vsk;
+	ssize_t record_len;
+	long timeout;
+	int err = 0;
+	DEFINE_WAIT(wait);
+
+	vsk = vsock_sk(sk);
+	transport = vsk->transport;
+
+	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+	msg_ready = false;
+	record_len = 0;
+
+	while (1) {
+		ssize_t fragment_len;
+
+		if (vsock_wait_data(sk, &wait, timeout, NULL, 0) <= 0) {
+			/* In case of any loop break(timeout, signal
+			 * interrupt or shutdown), we report user that
+			 * nothing was copied.
+			 */
+			err = 0;

Why we report that nothing was copied?

What happen to the bytes already copied in `msg`?

Seems i need to return result of vsock_wait_data()...

quoted

+			break;
+		}
+
+		fragment_len = transport->seqpacket_dequeue(vsk, msg, flags, &msg_ready);
+
+		if (fragment_len < 0) {
+			err = -ENOMEM;
+			break;
+		}
+
+		record_len += fragment_len;
+
+		if (msg_ready)
+			break;
+	}
+
+	if (sk->sk_err)
+		err = -sk->sk_err;
+	else if (sk->sk_shutdown & RCV_SHUTDOWN)
+		err = 0;
+
+	if (msg_ready && err == 0) {
+		/* User sets MSG_TRUNC, so return real length of
+		 * packet.
+		 */
+		if (flags & MSG_TRUNC)
+			err = record_len;
+		else
+			err = len - msg_data_left(msg);
+
+		/* Always set MSG_TRUNC if real length of packet is
+		 * bigger than user's buffer.
+		 */
+		if (record_len > len)
+			msg->msg_flags |= MSG_TRUNC;
+	}
+
+	return err;
+}
+
static int
vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
			  int flags)

@@ -2029,7 +2096,10 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,

		goto out;
	}

-	err = __vsock_stream_recvmsg(sk, msg, len, flags);
+	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);
-- 
2.25.1