net: hns: fix skb->truesize underestimation

skb->truesize is not meant to be tracking amount of used bytes in a skb,
but amount of reserved/consumed bytes in memory.

For instance, if we use a single byte in last page fragment, we have to
account the full size of the fragment.

So skb_add_rx_frag needs to calculate the length of the entire buffer into
turesize.

Fixes: 9cbe9fd5 ("net: hns: optimize XGE capability by reducing cpu usage")
Signed-off-by: Huazhong tan <tanhuazhong@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns/hns_enet.c

@@ -531,7 +531,7 @@ static void hns_nic_reuse_page(struct sk_buff *skb, int i,
 	}
 
 	skb_add_rx_frag(skb, i, desc_cb->priv, desc_cb->page_offset + pull_len,
-			size - pull_len, truesize - pull_len);
+			size - pull_len, truesize);
 
 	 /* avoid re-using remote pages,flag default unreuse */
 	if (unlikely(page_to_nid(desc_cb->priv) != numa_node_id()))