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

[Stefano Garzarella <sgarzare@redhat.com>]

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@kaspersky.com>
>---
> 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