> -----Original Message-----
> From: Stephen Hemminger <step...@networkplumber.org>
> Sent: Wednesday, May 15, 2019 4:03 AM
> To: KY Srinivasan <k...@microsoft.com>; Haiyang Zhang
> <haiya...@microsoft.com>; da...@davemloft.net
> Cc: netdev@vger.kernel.org; Stephen Hemminger <sthem...@microsoft.com>
> Subject: [RFC 1/2] netvsc: invoke xdp_generic from VF frame handler
>
> XDP generic does not work correctly with the Hyper-V/Azure netvsc device
> because of packet processing order. Only packets on the synthetic path get
> seen by the XDP program. The VF device packets are not seen.
>
> By the time the packets that arrive on the VF are handled by netvsc after the
> first pass of XDP generic (on the VF) has already been done.
>
> A fix for the netvsc device is to do this in the VF packet handler.
> by directly calling do_xdp_generic() if XDP program is present on the parent
> device.
>
> A riskier but maybe better alternative would be to do this netdev core code
> after the receive handler is invoked (if RX_HANDLER_ANOTHER is returned).
>
> Fixes: 0c195567a8f6 ("netvsc: transparent VF management")
> Signed-off-by: Stephen Hemminger <sthem...@microsoft.com>
> ---
> drivers/net/hyperv/netvsc_drv.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index 06393b215102..bb0fc1869bde 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -1999,9 +1999,15 @@ static rx_handler_result_t
> netvsc_vf_handle_frame(struct sk_buff **pskb)
> struct net_device_context *ndev_ctx = netdev_priv(ndev);
> struct netvsc_vf_pcpu_stats *pcpu_stats
> = this_cpu_ptr(ndev_ctx->vf_stats);
> + struct bpf_prog *xdp_prog;
>
> skb->dev = ndev;
>
> + xdp_prog = rcu_dereference(ndev->xdp_prog);
> + if (xdp_prog &&
> + do_xdp_generic(xdp_prog, skb) != XDP_PASS)
> + return RX_HANDLER_CONSUMED;
Looks fine overall.
The function do_xdp_generic() already checks NULL on xdp_prog,
so we don't need to check it in our code.
int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
{
if (xdp_prog) {
Thanks,
- Haiyang
