Re: [RFC PATCH v6 11/22] virtio/vsock: dequeue callback for SOCK_SEQPACKET

[Stefano Garzarella]

On Sun, Mar 07, 2021 at 09:02:01PM +0300, Arseny Krasnov wrote:
> This adds transport callback and it's logic for SEQPACKET dequeue.
> Callback fetches RW packets from rx queue of socket until whole record
> is copied(if user's buffer is full, user is not woken up). This is done
> to not stall sender, because if we wake up user and it leaves syscall,
> nobody will send credit update for rest of record, and sender will wait
> for next enter of read syscall at receiver's side. So if user buffer is
> full, we just send credit update and drop data. If during copy SEQ_BEGIN
> was found(and not all data was copied), copying is restarted by reset
> user's iov iterator(previous unfinished data is dropped).
>
> Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
> ---
> include/linux/virtio_vsock.h            |  13 +++
> include/uapi/linux/virtio_vsock.h       |  16 ++++
> net/vmw_vsock/virtio_transport_common.c | 116 ++++++++++++++++++++++++
> 3 files changed, 145 insertions(+)
>
> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> index dc636b727179..466a5832d2f5 100644
> --- a/include/linux/virtio_vsock.h
> +++ b/include/linux/virtio_vsock.h
> @@ -18,6 +18,12 @@ enum {
> 	VSOCK_VQ_MAX    = 3,
> };
>
> +struct virtio_vsock_seqpack_state {
> +	u32 user_read_seq_len;
> +	u32 user_read_copied;
> +	u32 curr_rx_msg_id;
> +};
> +
> /* Per-socket state (accessed via vsk->trans) */
> struct virtio_vsock_sock {
> 	struct vsock_sock *vsk;
> @@ -36,6 +42,8 @@ struct virtio_vsock_sock {
> 	u32 rx_bytes;
> 	u32 buf_alloc;
> 	struct list_head rx_queue;
> +
> +	struct virtio_vsock_seqpack_state seqpacket_state;

Following 'virtio_vsock_seq_hdr', maybe we can shorten in:

        struct virtio_vsock_seq_state seq_state;

The rest LGTM.