On Tue, Feb 09, 2021 at 07:02:01PM +0000, Dr. David Alan Gilbert (git) wrote:
> +static uint64_t vhost_user_slave_handle_vring_host_notifier(
> +                struct vhost_dev *dev,
> +               VhostUserVringArea *area,
> +               int fd)

Indentation looks off. Only worth changing if you respin.

> @@ -1398,7 +1399,8 @@ static void slave_read(void *opaque)
>      struct vhost_user *u = dev->opaque;
>      VhostUserHeader hdr = { 0, };
>      VhostUserPayload payload = { 0, };
> -    int size, ret = 0;
> +    int size;
> +    uint64_t ret = 0;
>      struct iovec iov;
>      struct msghdr msgh;
>      int fd[VHOST_USER_SLAVE_MAX_FDS];
> @@ -1472,7 +1474,7 @@ static void slave_read(void *opaque)
>          break;
>      default:
>          error_report("Received unexpected msg type: %d.", hdr.request);
> -        ret = -EINVAL;
> +        ret = (uint64_t)-EINVAL;

The !!ret was removed below so it would have previously been true (1).
Now it has changed value.

If there is no specific reason to change the value, please keep it true
(1) just in case a vhost-user device backend depends on that value.