Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 25 Feb 2020 06:18:01 -0500
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Yuya Kusakabe <yuya.kusakabe@gmail.com>
Cc:     jasowang@redhat.com, andriin@fb.com, ast@kernel.org,
        bpf@vger.kernel.org, daniel@iogearbox.net, davem@davemloft.net,
        hawk@kernel.org, john.fastabend@gmail.com, kafai@fb.com,
        kuba@kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, songliubraving@fb.com, yhs@fb.com
Subject: Re: [PATCH bpf-next v6 1/2] virtio_net: keep vnet header zeroed if
 XDP is loaded for small buffer
Message-ID: <20200225061501-mutt-send-email-mst@kernel.org>
References: <20200225033103.437305-1-yuya.kusakabe@gmail.com>
 <20200225033212.437563-1-yuya.kusakabe@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200225033212.437563-1-yuya.kusakabe@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Feb 25, 2020 at 12:32:11PM +0900, Yuya Kusakabe wrote:
> We do not want to care about the vnet header in receive_small() if XDP
> is loaded, since we can not know whether or not the packet is modified
> by XDP.
> 
> Fixes: f6b10209b90d ("virtio-net: switch to use build_skb() for small buffer")
> Signed-off-by: Yuya Kusakabe <yuya.kusakabe@gmail.com>

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


> ---
>  drivers/net/virtio_net.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 2fe7a3188282..f39d0218bdaa 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -735,10 +735,10 @@ static struct sk_buff *receive_small(struct net_device *dev,
>  	}
>  	skb_reserve(skb, headroom - delta);
>  	skb_put(skb, len);
> -	if (!delta) {
> +	if (!xdp_prog) {
>  		buf += header_offset;
>  		memcpy(skb_vnet_hdr(skb), buf, vi->hdr_len);
> -	} /* keep zeroed vnet hdr since packet was changed by bpf */
> +	} /* keep zeroed vnet hdr since XDP is loaded */
>  
>  err:
>  	return skb;
> -- 
> 2.24.1