Commit 6b9c129c authored by Maciej Fijalkowski's avatar Maciej Fijalkowski Committed by Jakub Kicinski
Browse files

xsk: remove @first_frag from xsk_build_skb() 



Instead of using auxiliary boolean that tracks if we are at first frag
when gathering all elements of skb, same functionality can be achieved
with checking if skb_shared_info::nr_frags is 0.

Remove @first_frag but be careful around xsk_build_skb_zerocopy() and
NULL the skb pointer when it failed so that common error path does not
incorrectly interpret it during decision whether to call kfree_skb().

Signed-off-by: default avatarMaciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: default avatarStanislav Fomichev <sdf@fomichev.me>
Reviewed-by: default avatarJason Xing <kerneljasonxing@gmail.com>
Acked-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250925160009.2474816-3-maciej.fijalkowski@intel.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent c30d0849

net/xdp/xsk.c

+3 −5
Original line number Diff line number Diff line
@@ -730,13 +730,13 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, 
	struct xsk_tx_metadata *meta = NULL;

	struct net_device *dev = xs->dev;

	struct sk_buff *skb = xs->skb;

	bool first_frag = false;

	int err;



	if (dev->priv_flags & IFF_TX_SKB_NO_LINEAR) {

		skb = xsk_build_skb_zerocopy(xs, desc);

		if (IS_ERR(skb)) {

			err = PTR_ERR(skb);

			skb = NULL;

			goto free_err;

		}

	} else {
@@ -747,8 +747,6 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, 
		len = desc->len;



		if (!skb) {

			first_frag = true;



			hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(dev->needed_headroom));

			tr = dev->needed_tailroom;

			skb = sock_alloc_send_skb(&xs->sk, hr + len + tr, 1, &err);
@@ -798,7 +796,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, 
			list_add_tail(&xsk_addr->addr_node, &XSKCB(skb)->addrs_list);

		}



		if (first_frag && desc->options & XDP_TX_METADATA) {

		if (!skb_shinfo(skb)->nr_frags && desc->options & XDP_TX_METADATA) {

			if (unlikely(xs->pool->tx_metadata_len == 0)) {

				err = -EINVAL;

				goto free_err;
@@ -840,7 +838,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, 
	return skb;



free_err:

	if (first_frag && skb)

	if (skb && !skb_shinfo(skb)->nr_frags)

		kfree_skb(skb);



	if (err == -EOVERFLOW) {