Re: [PATCH v7 05/12] vhost_net: Add NetClientInfo prepare callback

[Jason Wang]

On Fri, Aug 5, 2022 at 2:29 AM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> This is used by the backend to perform actions before the device is
> started.
>
> In particular, vdpa net use it to map CVQ buffers to the device, so it
> can send control commands using them.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>  include/net/net.h  | 2 ++
>  hw/net/vhost_net.c | 7 +++++++
>  2 files changed, 9 insertions(+)
>
> diff --git a/include/net/net.h b/include/net/net.h
> index 523136c7ac..3416bb3d46 100644
> --- a/include/net/net.h
> +++ b/include/net/net.h
> @@ -44,6 +44,7 @@ typedef struct NICConf {
>
>  typedef void (NetPoll)(NetClientState *, bool enable);
>  typedef bool (NetCanReceive)(NetClientState *);
> +typedef int (NetPrepare)(NetClientState *);
>  typedef ssize_t (NetReceive)(NetClientState *, const uint8_t *, size_t);
>  typedef ssize_t (NetReceiveIOV)(NetClientState *, const struct iovec *, int);
>  typedef void (NetCleanup) (NetClientState *);
> @@ -71,6 +72,7 @@ typedef struct NetClientInfo {
>      NetReceive *receive_raw;
>      NetReceiveIOV *receive_iov;
>      NetCanReceive *can_receive;
> +    NetPrepare *prepare;

So it looks to me the function is paired with a stop that is
introduced in the following patch.

Maybe we should use "start/stop" instead of "prepare/stop"?

Thanks

>      NetCleanup *cleanup;
>      LinkStatusChanged *link_status_changed;
>      QueryRxFilter *query_rx_filter;
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index ccac5b7a64..e1150d7532 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -244,6 +244,13 @@ static int vhost_net_start_one(struct vhost_net *net,
>      struct vhost_vring_file file = { };
>      int r;
>
> +    if (net->nc->info->prepare) {
> +        r = net->nc->info->prepare(net->nc);
> +        if (r < 0) {
> +            return r;
> +        }
> +    }
> +
>      r = vhost_dev_enable_notifiers(&net->dev, dev);
>      if (r < 0) {
>          goto fail_notifiers;
> --
> 2.31.1
>