Re: [RFC PATCH v1 3/7] vhost/vsock: support MSG_EOR bit processing

[Stefano Garzarella]

On Mon, Jul 26, 2021 at 07:33:38PM +0300, Arseny Krasnov wrote:
> It works in the same way as 'end-of-message' bit: if packet has
> 'EOM' bit, also check for 'EOR' bit.
>
> Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
> ---
> drivers/vhost/vsock.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 3b55de70ac77..3e2b150f9c6f 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -115,6 +115,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 		size_t iov_len, payload_len;
> 		int head;
> 		bool restore_msg_eom_flag = false;
> +		bool restore_msg_eor_flag = false;

Since we now have 2 flags to potentially restore, we could use a single
variable (e.g. uint32_t flags_to_restore), initialized to 0.

We can set all the flags we need to restore and then simply put it
in or with the `pkt->hdr.flags` field.

> 		spin_lock_bh(&vsock->send_pkt_list_lock);
> 		if (list_empty(&vsock->send_pkt_list)) {
> @@ -188,6 +189,11 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 			if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) {
> 				pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
> 				restore_msg_eom_flag = true;
> +
> +				if (le32_to_cpu(pkt->hdr.flags & VIRTIO_VSOCK_SEQ_EOR)) {
                                                               ^
Here it should be `le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR`

> +					pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> +					restore_msg_eor_flag = true;
> +				}
> 			}
> 		}
>
> @@ -224,9 +230,13 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 		 * to send it with the next available buffer.
> 		 */
> 		if (pkt->off < pkt->len) {
> -			if (restore_msg_eom_flag)
> +			if (restore_msg_eom_flag) {
> 				pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
>
> +				if (restore_msg_eor_flag)
> +					pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> +			}
> +

If we use a single variable, here we can simply do:

			pkt->hdr.flags |= cpu_to_le32(flags_to_restore);

Stefano