linux-kernel - Re: [PATCH net 2/4] virtio-net: correctly transmit XDP buff after linearizing

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Date:   Mon, 21 May 2018 18:03:51 +0300
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        John Fastabend <john.fastabend@...il.com>
Subject: Re: [PATCH net 2/4] virtio-net: correctly transmit XDP buff after
 linearizing

On Mon, May 21, 2018 at 04:35:04PM +0800, Jason Wang wrote:
> We should not go for the error path after successfully transmitting a
> XDP buffer after linearizing. Since the error path may try to pop and
> drop next packet and increase the drop counters. Fixing this by simply
> drop the refcnt of original page and go for xmit path.
> 
> Fixes: 72979a6c3590 ("virtio_net: xdp, add slowpath case for non contiguous buffers")
> Cc: John Fastabend <john.fastabend@...il.com>
> Signed-off-by: Jason Wang <jasowang@...hat.com>

Acked-by: Michael S. Tsirkin <mst@...hat.com>

> ---
>  drivers/net/virtio_net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index c15d240..6260d65 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -775,7 +775,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>  			}
>  			*xdp_xmit = true;
>  			if (unlikely(xdp_page != page))
> -				goto err_xdp;
> +				put_page(page);
>  			rcu_read_unlock();
>  			goto xdp_xmit;
>  		case XDP_REDIRECT:
> -- 
> 2.7.4