Re: [PATCH bpf-next v4] virtio_net: add XDP meta data support

On 2/5/20 2:33 PM, Michael S. Tsirkin wrote:

On Tue, Feb 04, 2020 at 04:16:55PM +0900, Yuya Kusakabe wrote:

quoted

@@ -852,8 +868,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 			 * adjustments. Note other cases do not build an
 			 * skb and avoid using offset
 			 */
-			offset = xdp.data -
-					page_address(xdp_page) - vi->hdr_len;
+			metasize = xdp.data - xdp.data_meta;
+			offset = xdp.data - page_address(xdp_page) -
+				 vi->hdr_len - metasize;
 
 			/* recalculate len if xdp.data or xdp.data_end were
 			 * adjusted

Tricky to get one's head around.
Can you pls update the comment above to document the new math?

Thank you for your review.

I will update the comment on next patch.