Re: [RFC PATCH v6 06/22] af_vsock: implement send logic for SEQPACKET

[Stefano Garzarella <sgarzare@redhat.com>]

On Sun, Mar 07, 2021 at 09:00:26PM +0300, Arseny Krasnov wrote:
>This adds some logic to current stream enqueue function for SEQPACKET
>support:
>1) Use transport's seqpacket enqueue callback.
>2) Return value from enqueue function is whole record length or error
>   for SOCK_SEQPACKET.
>
>Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
>---
> include/net/af_vsock.h   |  2 ++
> net/vmw_vsock/af_vsock.c | 22 ++++++++++++++++------
> 2 files changed, 18 insertions(+), 6 deletions(-)
>
>diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>index a8c4039e40cf..aed306292ab3 100644
>--- a/include/net/af_vsock.h
>+++ b/include/net/af_vsock.h
>@@ -139,6 +139,8 @@ struct vsock_transport {
> 	size_t (*seqpacket_seq_get_len)(struct vsock_sock *vsk);
> 	int (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
> 				 int flags, bool *msg_ready);
>+	int (*seqpacket_enqueue)(struct vsock_sock *vsk, struct msghdr *msg,
>+				 int flags, size_t len);
>
> 	/* Notification. */
> 	int (*notify_poll_in)(struct vsock_sock *, size_t, bool *);
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index 5bf64a3e678a..a031f165494d 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1830,9 +1830,14 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
> 		 * responsibility to check how many bytes we were able to send.
> 		 */
>
>-		written = transport->stream_enqueue(
>-				vsk, msg,
>-				len - total_written);
>+		if (sk->sk_type == SOCK_SEQPACKET) {
>+			written = transport->seqpacket_enqueue(vsk,
>+						msg, msg->msg_flags,

I think we can avoid to pass 'msg->msg_flags', since the transport can 
access it through the 'msg' pointer, right?

>+						len - total_written);
>+		} else {
>+			written = transport->stream_enqueue(vsk,
>+					msg, len - total_written);
>+		}
> 		if (written < 0) {
> 			err = -ENOMEM;
> 			goto out_err;
>@@ -1844,12 +1849,17 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
> 				vsk, written, &send_data);
> 		if (err < 0)
> 			goto out_err;
>-
> 	}
>
> out_err:
>-	if (total_written > 0)
>-		err = total_written;
>+	if (total_written > 0) {
>+		/* Return number of written bytes only if:
>+		 * 1) SOCK_STREAM socket.
>+		 * 2) SOCK_SEQPACKET socket when whole buffer is sent.
>+		 */
>+		if (sk->sk_type == SOCK_STREAM || total_written == len)
>+			err = total_written;
>+	}
> out:
> 	release_sock(sk);
> 	return err;
>-- 
>2.25.1
>