Re: [RFC PATCH v9 13/19] virtio/vsock: rest of SOCK_SEQPACKET support

[Stefano Garzarella <sgarzare@redhat.com>]

On Sat, May 08, 2021 at 07:35:54PM +0300, Arseny Krasnov wrote:
>This adds rest of logic for SEQPACKET:
>1) Send SHUTDOWN on socket close for SEQPACKET type.
>2) Set SEQPACKET packet type during send.
>3) 'seqpacket_allow' flag to virtio transport.

Please update this commit message, point 3 is not included anymore in 
this patch, right?

>4) Set 'VIRTIO_VSOCK_SEQ_EOR' bit in flags for last
>   packet of message.
>
>Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
>---
> v8 -> v9:
> 1) Use cpu_to_le32() to set VIRTIO_VSOCK_SEQ_EOR.
>
> include/linux/virtio_vsock.h            |  4 ++++
> net/vmw_vsock/virtio_transport_common.c | 17 +++++++++++++++--
> 2 files changed, 19 insertions(+), 2 deletions(-)
>
>diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
>index 02acf6e9ae04..7360ab7ea0af 100644
>--- a/include/linux/virtio_vsock.h
>+++ b/include/linux/virtio_vsock.h
>@@ -80,6 +80,10 @@ virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
> 			       struct msghdr *msg,
> 			       size_t len, int flags);
>
>+int
>+virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
>+				   struct msghdr *msg,
>+				   size_t len);
> ssize_t
> virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
> 				   struct msghdr *msg,
>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>index 7fea0a2192f7..b6608b4ac7c2 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -74,6 +74,10 @@ virtio_transport_alloc_pkt(struct virtio_vsock_pkt_info *info,
> 		err = memcpy_from_msg(pkt->buf, info->msg, len);
> 		if (err)
> 			goto out;
>+
>+		if (info->msg->msg_iter.count == 0)

Also here is better `msg_data_left(info->msg)`

>+			pkt->hdr.flags = cpu_to_le32(info->flags |
>+						VIRTIO_VSOCK_SEQ_EOR);

Re-thinking an alternative could be to set EOR here...

			info->flags |= VIRTIO_VSOCK_SEQ_EOR;

> 	}

... and move pkt->hdr.flags assignment after this block:

	pkt->hdr.flags = cpu_to_le32(info->flags);

But I don't have a strong opinion on that.

>
> 	trace_virtio_transport_alloc_pkt(src_cid, src_port,