Re: [RFC PATCH v2 1/5] virtio/vsock: add 'VIRTIO_VSOCK_SEQ_EOM' bit

[Stefano Garzarella]

On Tue, Aug 10, 2021 at 02:39:53PM +0300, Arseny Krasnov wrote:

The title is confusing, we are renaming EOR in EOM.

> This bit is used to mark end of messages('EOM' - end of message), while
> 'VIRIO_VSOCK_SEQ_EOR' is used to pass MSG_EOR. Also rename 'record' to
> 'message' in implementation as it is different things.
>
> Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
> ---
> drivers/vhost/vsock.c                   | 12 ++++++------
> include/uapi/linux/virtio_vsock.h       |  3 ++-
> net/vmw_vsock/virtio_transport_common.c | 14 +++++++-------
> 3 files changed, 15 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index f249622ef11b..feaf650affbe 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -178,15 +178,15 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 			 * small rx buffers, headers of packets in rx queue are
> 			 * created dynamically and are initialized with 
> 			 header
> 			 * of current packet(except length). But in case of
> -			 * SOCK_SEQPACKET, we also must clear record delimeter
> -			 * bit(VIRTIO_VSOCK_SEQ_EOR). Otherwise, instead of one
> -			 * packet with delimeter(which marks end of record),
> +			 * SOCK_SEQPACKET, we also must clear message delimeter
> +			 * bit(VIRTIO_VSOCK_SEQ_EOM). Otherwise, instead of one
> +			 * packet with delimeter(which marks end of message),
> 			 * there will be sequence of packets with delimeter
> 			 * bit set. After initialized header will be copied to
> 			 * rx buffer, this bit will be restored.
> 			 */
> -			if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR) {
> -				pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> +			if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) {
> +				pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
> 				restore_flag = true;
> 			}
> 		}
> @@ -225,7 +225,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 		 */
> 		if (pkt->off < pkt->len) {
> 			if (restore_flag)
> -				pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> +				pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
>
> 			/* We are queueing the same virtio_vsock_pkt to handle
> 			 * the remaining bytes, and we want to deliver it
> diff --git a/include/uapi/linux/virtio_vsock.h b/include/uapi/linux/virtio_vsock.h
> index 3dd3555b2740..64738838bee5 100644
> --- a/include/uapi/linux/virtio_vsock.h
> +++ b/include/uapi/linux/virtio_vsock.h
> @@ -97,7 +97,8 @@ enum virtio_vsock_shutdown {
>
> /* VIRTIO_VSOCK_OP_RW flags values */
> enum virtio_vsock_rw {
> -	VIRTIO_VSOCK_SEQ_EOR = 1,
> +	VIRTIO_VSOCK_SEQ_EOM = 1,
> +	VIRTIO_VSOCK_SEQ_EOR = 2,
        ^
I think is better to add this new flag in a separate patch.

> };
>
> #endif /* _UAPI_LINUX_VIRTIO_VSOCK_H */
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index 081e7ae93cb1..4d5a93beceb0 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -77,7 +77,7 @@ virtio_transport_alloc_pkt(struct virtio_vsock_pkt_info *info,
>
> 		if (msg_data_left(info->msg) == 0 &&
> 		    info->type == VIRTIO_VSOCK_TYPE_SEQPACKET)
> -			pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> +			pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
> 	}
>
> 	trace_virtio_transport_alloc_pkt(src_cid, src_port,
> @@ -457,7 +457,7 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
> 				dequeued_len += pkt_len;
> 		}
>
> -		if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR) {
> +		if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) {
> 			msg_ready = true;
> 			vvs->msg_count--;
> 		}
> @@ -1029,7 +1029,7 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
> 		goto out;
> 	}
>
> -	if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR)
> +	if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM)
> 		vvs->msg_count++;
>
> 	/* Try to copy small packets into the buffer of last packet queued,
> @@ -1044,12 +1044,12 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
>
> 		/* If there is space in the last packet queued, we copy the
> 		 * new packet in its buffer. We avoid this if the last packet
> -		 * queued has VIRTIO_VSOCK_SEQ_EOR set, because this is
> -		 * delimiter of SEQPACKET record, so 'pkt' is the first packet
> -		 * of a new record.
> +		 * queued has VIRTIO_VSOCK_SEQ_EOM set, because this is
> +		 * delimiter of SEQPACKET message, so 'pkt' is the first packet
> +		 * of a new message.
> 		 */
> 		if ((pkt->len <= last_pkt->buf_len - last_pkt->len) &&
> -		    !(le32_to_cpu(last_pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR)) {
> +		    !(le32_to_cpu(last_pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM)) {
> 			memcpy(last_pkt->buf + last_pkt->len, pkt->buf,
> 			       pkt->len);
> 			last_pkt->len += pkt->len;
> --
> 2.25.1

The rest LGTM!

Thanks,
Stefano