Re: [RFC PATCH v7 14/22] virtio/vsock: rest of SOCK_SEQPACKET support

[Stefano Garzarella]

On Tue, Mar 23, 2021 at 04:13:29PM +0300, Arseny Krasnov wrote:
> This adds rest of logic for SEQPACKET:
> 1) SEQPACKET specific functions which send SEQ_BEGIN/SEQ_END.
>   Note that both functions may sleep to wait enough space for
>   SEQPACKET header.
> 2) SEQ_BEGIN/SEQ_END in TAP packet capture.
> 3) Send SHUTDOWN on socket close for SEQPACKET type.
> 4) Set SEQPACKET packet type during send.
> 5) Set MSG_EOR in flags for SEQPACKET during send.
> 6) 'seqpacket_allow' flag to virtio transport.
>
> Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
> ---
> v6 -> v7:
> In 'virtio_transport_seqpacket_enqueue()', 'next_tx_msg_id' is updated
> in both cases when message send successfully or error occured.
>
> include/linux/virtio_vsock.h            |  7 ++
> net/vmw_vsock/virtio_transport_common.c | 88 ++++++++++++++++++++++++-
> 2 files changed, 93 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> index 0e3aa395c07c..ab5f56fd7251 100644
> --- a/include/linux/virtio_vsock.h
> +++ b/include/linux/virtio_vsock.h
> @@ -22,6 +22,7 @@ struct virtio_vsock_seq_state {
> 	u32 user_read_seq_len;
> 	u32 user_read_copied;
> 	u32 curr_rx_msg_id;
> +	u32 next_tx_msg_id;
> };
>
> /* Per-socket state (accessed via vsk->trans) */
> @@ -76,6 +77,8 @@ struct virtio_transport {
>
> 	/* Takes ownership of the packet */
> 	int (*send_pkt)(struct virtio_vsock_pkt *pkt);
> +
> +	bool seqpacket_allow;
> };
>
> ssize_t
> @@ -89,6 +92,10 @@ virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
> 			       size_t len, int flags);
>
> int
> +virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
> +				   struct msghdr *msg,
> +				   size_t len);
> +int
> virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
> 				   struct msghdr *msg,
> 				   int flags,
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index bfe0d7026bf8..01a56c7da8bd 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -139,6 +139,8 @@ 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:
> +	case VIRTIO_VSOCK_OP_SEQ_END:
> 		hdr->op = cpu_to_le16(AF_VSOCK_OP_CONTROL);
> 		break;
> 	default:
> @@ -187,7 +189,12 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
> 	struct virtio_vsock_pkt *pkt;
> 	u32 pkt_len = info->pkt_len;
>
> -	info->type = VIRTIO_VSOCK_TYPE_STREAM;
> +	info->type = virtio_transport_get_type(sk_vsock(vsk));
> +
> +	if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET &&
> +	    info->msg &&
> +	    info->msg->msg_flags & MSG_EOR)
> +		info->flags |= VIRTIO_VSOCK_RW_EOR;
>
> 	t_ops = virtio_transport_get_ops(vsk);
> 	if (unlikely(!t_ops))
> @@ -401,6 +408,43 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
> 	return err;
> }
>
> +static int virtio_transport_seqpacket_send_ctrl(struct vsock_sock *vsk,
> +						int type,
> +						size_t len,
> +						int flags)
> +{
> +	struct virtio_vsock_sock *vvs = vsk->trans;
> +	struct virtio_vsock_pkt_info info = {
> +		.op = type,
> +		.vsk = vsk,
> +		.pkt_len = sizeof(struct virtio_vsock_seq_hdr)
> +	};
> +
> +	struct virtio_vsock_seq_hdr seq_hdr = {
> +		.msg_id = cpu_to_le32(vvs->seq_state.next_tx_msg_id),
> +		.msg_len = cpu_to_le32(len)
> +	};
> +
> +	struct kvec seq_hdr_kiov = {
> +		.iov_base = (void *)&seq_hdr,
> +		.iov_len = sizeof(struct virtio_vsock_seq_hdr)
> +	};
> +
> +	struct msghdr msg = {0};
> +
> +	//XXX: do we need 'vsock_transport_send_notify_data' pointer?
> +	if (vsock_wait_space(sk_vsock(vsk),
> +			     sizeof(struct virtio_vsock_seq_hdr),
> +			     flags, NULL))
> +		return -1;
> +
> +	iov_iter_kvec(&msg.msg_iter, WRITE, &seq_hdr_kiov, 1, sizeof(seq_hdr));
> +
> +	info.msg = &msg;
> +
> +	return virtio_transport_send_pkt_info(vsk, &info);
> +}
> +
> static inline void virtio_transport_remove_pkt(struct virtio_vsock_pkt *pkt)
> {
> 	list_del(&pkt->list);
> @@ -595,6 +639,46 @@ virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
> }
> EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue);
>
> +int
> +virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
> +				   struct msghdr *msg,
> +				   size_t len)
> +{
> +	int written = -1;
> +
> +	if (msg->msg_iter.iov_offset == 0) {
> +		/* Send SEQBEGIN. */
> +		if (virtio_transport_seqpacket_send_ctrl(vsk,
> +							 VIRTIO_VSOCK_OP_SEQ_BEGIN,
> +							 len,
> +							 msg->msg_flags) < 0)
> +			goto out;
> +	}
> +
> +	written = virtio_transport_stream_enqueue(vsk, msg, len);
> +
> +	if (written < 0)
> +		goto out;
> +
> +	if (msg->msg_iter.count == 0) {
> +		/* Send SEQEND. */
> +		virtio_transport_seqpacket_send_ctrl(vsk,
> +						     VIRTIO_VSOCK_OP_SEQ_END,
> +						     0,
> +						     msg->msg_flags);

What happen if this fail?

In the previous version we returned -1, now we return the bytes 
transmitted, is that right?

The rest LGTM.

> +	}
> +out:
> +	/* Update next id on error or message transmission done. */
> +	if (written < 0 || msg->msg_iter.count == 0) {
> +		struct virtio_vsock_sock *vvs = vsk->trans;
> +
> +		vvs->seq_state.next_tx_msg_id++;
> +	}
> +
> +	return written;
> +}
> +EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_enqueue);
> +
> int
> virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
> 			       struct msghdr *msg,
> @@ -1014,7 +1098,7 @@ void virtio_transport_release(struct vsock_sock *vsk)
> 	struct sock *sk = &vsk->sk;
> 	bool remove_sock = true;
>
> -	if (sk->sk_type == SOCK_STREAM)
> +	if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)
> 		remove_sock = virtio_transport_close(vsk);
>
> 	list_for_each_entry_safe(pkt, tmp, &vvs->rx_queue, list) {
> --
> 2.25.1