Merge branch 'virtio_net-build_skb-fixes'

Xuan Zhuo says:

====================
virtio-net: fix for build_skb()

The logic of this piece is really messy. Fortunately, my refactored patch can be
completed with a small amount of testing.
====================
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/virtio_net.c

@@ -401,18 +401,13 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
 	/* If headroom is not 0, there is an offset between the beginning of the
 	 * data and the allocated space, otherwise the data and the allocated
 	 * space are aligned.
+	 *
+	 * Buffers with headroom use PAGE_SIZE as alloc size, see
+	 * add_recvbuf_mergeable() + get_mergeable_buf_len()
 	 */
-	if (headroom) {
-		/* Buffers with headroom use PAGE_SIZE as alloc size,
-		 * see add_recvbuf_mergeable() + get_mergeable_buf_len()
-		 */
-		truesize = PAGE_SIZE;
-		tailroom = truesize - len - offset;
-		buf = page_address(page);
-	} else {
-		tailroom = truesize - len;
-		buf = p;
-	}
+	truesize = headroom ? PAGE_SIZE : truesize;
+	tailroom = truesize - len - headroom;
+	buf = p - headroom;
 
 	len -= hdr_len;
 	offset += hdr_padded_len;
@@ -958,7 +953,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 				put_page(page);
 				head_skb = page_to_skb(vi, rq, xdp_page, offset,
 						       len, PAGE_SIZE, false,
-						       metasize, headroom);
+						       metasize,
+						       VIRTIO_XDP_HEADROOM);
 				return head_skb;
 			}
 			break;