xsk: avoid overwriting skb fields for multi-buffer traffic

We are unnecessarily setting a bunch of skb fields per each processed
descriptor, which is redundant for fragmented frames.

Let us set these respective members for first fragment only.

Signed-off-by: Maciej Fijalkowski <[email protected]>

Author: mfijalko

net/xdp/xsk.c

@@ -758,6 +758,10 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
 				goto free_err;
 
 			xsk_set_destructor_arg(skb, desc->addr);
+			skb->dev = dev;
+			skb->priority = READ_ONCE(xs->sk.sk_priority);
+			skb->mark = READ_ONCE(xs->sk.sk_mark);
+			skb->destructor = xsk_destruct_skb;
 		} else {
 			int nr_frags = skb_shinfo(skb)->nr_frags;
 			struct xsk_addr_node *xsk_addr;
@@ -826,14 +830,10 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
 
 			if (meta->flags & XDP_TXMD_FLAGS_LAUNCH_TIME)
 				skb->skb_mstamp_ns = meta->request.launch_time;
+			xsk_tx_metadata_to_compl(meta, &skb_shinfo(skb)->xsk_meta);
 		}
 	}
 
-	skb->dev = dev;
-	skb->priority = READ_ONCE(xs->sk.sk_priority);
-	skb->mark = READ_ONCE(xs->sk.sk_mark);
-	skb->destructor = xsk_destruct_skb;
-	xsk_tx_metadata_to_compl(meta, &skb_shinfo(skb)->xsk_meta);
 	xsk_inc_num_desc(skb);
 
 	return skb;