Re: [RFC PATCH v3 10/13] virtio/vsock: rest of SOCK_SEQPACKET support

On Fri, Jan 29, 2021 at 07:00:16PM +0300, Arseny Krasnov wrote:

On 29.01.2021 14:03, Stefano Garzarella wrote:

quoted

On Mon, Jan 25, 2021 at 02:15:26PM +0300, Arseny Krasnov wrote:

quoted

This adds rest of logic for SEQPACKET:
1) Shared functions for packet sending now set valid type of packet
  according socket type.
2) SEQPACKET specific function like SEQ_BEGIN send and data dequeue.
3) TAP support for SEQPACKET is not so easy if it is necessary to
send whole record to TAP interface. This could be done by allocating
new packet when whole record is received, data of record must be
copied to TAP packet.

Signed-off-by: Arseny Krasnov <redacted>
---
include/linux/virtio_vsock.h            |  7 ++++
net/vmw_vsock/virtio_transport_common.c | 55 +++++++++++++++++++++----
2 files changed, 55 insertions(+), 7 deletions(-)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index af8705ea8b95..ad9783df97c9 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h

@@ -84,7 +84,14 @@ virtio_transport_dgram_dequeue(struct vsock_sock *vsk,

			       struct msghdr *msg,
			       size_t len, int flags);

+bool virtio_transport_seqpacket_seq_send_len(struct vsock_sock *vsk, size_t len);
size_t virtio_transport_seqpacket_seq_get_len(struct vsock_sock *vsk);
+ssize_t
+virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
+				   struct msghdr *msg,
+				   size_t len,
+				   int type);
+
s64 virtio_transport_stream_has_data(struct vsock_sock *vsk);
s64 virtio_transport_stream_has_space(struct vsock_sock *vsk);

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 90f9feef9d8f..fab14679ca7b 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c

@@ -139,6 +139,7 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)

		break;
	case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
	case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
+	case VIRTIO_VSOCK_OP_SEQ_BEGIN:
		hdr->op = cpu_to_le16(AF_VSOCK_OP_CONTROL);
		break;
	default:

@@ -157,6 +158,10 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)

void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt)
{
+	/* TODO: implement tap support for SOCK_SEQPACKET. */

I think we should do this before merging SOCK_SEQPACKET support because
it can be very useful to use tcpdump to figure out what's going on, do
you think it's complicated?

It is not complicated if for TAP interface we will consider seqpacket

same as stream, e.g. TAP reader won't see whole record as one

packet,it will see fragments of record as in stream socket. Implement

Maybe as initial support we can have this limitation and complete it 
later.

normal interpretation of seqpacket is not complicated, but requires

some extra work. Ok, i'll check it

Thanks,
Stefano