veth: Introduce veth_xdp_buff wrapper for xdp_buff

No functional changes. Boilerplate to allow stuffing more data after xdp_buff.

Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Anatoly Burakov <anatoly.burakov@intel.com>
Cc: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
Cc: Maryam Tahhan <mtahhan@redhat.com>
Cc: xdp-hints@xdp-project.net
Cc: netdev@vger.kernel.org
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230119221536.3349901-10-sdf@google.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

drivers/net/veth.c

@@ -116,6 +116,10 @@ static struct {
 	{ "peer_ifindex" },
 };
 
+struct veth_xdp_buff {
+	struct xdp_buff xdp;
+};
+
 static int veth_get_link_ksettings(struct net_device *dev,
 				   struct ethtool_link_ksettings *cmd)
 {
@@ -592,23 +596,24 @@ static struct xdp_frame *veth_xdp_rcv_one(struct veth_rq *rq,
 	rcu_read_lock();
 	xdp_prog = rcu_dereference(rq->xdp_prog);
 	if (likely(xdp_prog)) {
-		struct xdp_buff xdp;
+		struct veth_xdp_buff vxbuf;
+		struct xdp_buff *xdp = &vxbuf.xdp;
 		u32 act;
 
-		xdp_convert_frame_to_buff(frame, &xdp);
-		xdp.rxq = &rq->xdp_rxq;
+		xdp_convert_frame_to_buff(frame, xdp);
+		xdp->rxq = &rq->xdp_rxq;
 
-		act = bpf_prog_run_xdp(xdp_prog, &xdp);
+		act = bpf_prog_run_xdp(xdp_prog, xdp);
 
 		switch (act) {
 		case XDP_PASS:
-			if (xdp_update_frame_from_buff(&xdp, frame))
+			if (xdp_update_frame_from_buff(xdp, frame))
 				goto err_xdp;
 			break;
 		case XDP_TX:
 			orig_frame = *frame;
-			xdp.rxq->mem = frame->mem;
-			if (unlikely(veth_xdp_tx(rq, &xdp, bq) < 0)) {
+			xdp->rxq->mem = frame->mem;
+			if (unlikely(veth_xdp_tx(rq, xdp, bq) < 0)) {
 				trace_xdp_exception(rq->dev, xdp_prog, act);
 				frame = &orig_frame;
 				stats->rx_drops++;
@@ -619,8 +624,8 @@ static struct xdp_frame *veth_xdp_rcv_one(struct veth_rq *rq,
 			goto xdp_xmit;
 		case XDP_REDIRECT:
 			orig_frame = *frame;
-			xdp.rxq->mem = frame->mem;
-			if (xdp_do_redirect(rq->dev, &xdp, xdp_prog)) {
+			xdp->rxq->mem = frame->mem;
+			if (xdp_do_redirect(rq->dev, xdp, xdp_prog)) {
 				frame = &orig_frame;
 				stats->rx_drops++;
 				goto err_xdp;
@@ -801,7 +806,8 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq,
 {
 	void *orig_data, *orig_data_end;
 	struct bpf_prog *xdp_prog;
-	struct xdp_buff xdp;
+	struct veth_xdp_buff vxbuf;
+	struct xdp_buff *xdp = &vxbuf.xdp;
 	u32 act, metalen;
 	int off;
 
@@ -815,22 +821,22 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq,
 	}
 
 	__skb_push(skb, skb->data - skb_mac_header(skb));
-	if (veth_convert_skb_to_xdp_buff(rq, &xdp, &skb))
+	if (veth_convert_skb_to_xdp_buff(rq, xdp, &skb))
 		goto drop;
 
-	orig_data = xdp.data;
-	orig_data_end = xdp.data_end;
+	orig_data = xdp->data;
+	orig_data_end = xdp->data_end;
 
-	act = bpf_prog_run_xdp(xdp_prog, &xdp);
+	act = bpf_prog_run_xdp(xdp_prog, xdp);
 
 	switch (act) {
 	case XDP_PASS:
 		break;
 	case XDP_TX:
-		veth_xdp_get(&xdp);
+		veth_xdp_get(xdp);
 		consume_skb(skb);
-		xdp.rxq->mem = rq->xdp_mem;
-		if (unlikely(veth_xdp_tx(rq, &xdp, bq) < 0)) {
+		xdp->rxq->mem = rq->xdp_mem;
+		if (unlikely(veth_xdp_tx(rq, xdp, bq) < 0)) {
 			trace_xdp_exception(rq->dev, xdp_prog, act);
 			stats->rx_drops++;
 			goto err_xdp;
@@ -839,10 +845,10 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq,
 		rcu_read_unlock();
 		goto xdp_xmit;
 	case XDP_REDIRECT:
-		veth_xdp_get(&xdp);
+		veth_xdp_get(xdp);
 		consume_skb(skb);
-		xdp.rxq->mem = rq->xdp_mem;
-		if (xdp_do_redirect(rq->dev, &xdp, xdp_prog)) {
+		xdp->rxq->mem = rq->xdp_mem;
+		if (xdp_do_redirect(rq->dev, xdp, xdp_prog)) {
 			stats->rx_drops++;
 			goto err_xdp;
 		}
@@ -862,7 +868,7 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq,
 	rcu_read_unlock();
 
 	/* check if bpf_xdp_adjust_head was used */
-	off = orig_data - xdp.data;
+	off = orig_data - xdp->data;
 	if (off > 0)
 		__skb_push(skb, off);
 	else if (off < 0)
@@ -871,21 +877,21 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq,
 	skb_reset_mac_header(skb);
 
 	/* check if bpf_xdp_adjust_tail was used */
-	off = xdp.data_end - orig_data_end;
+	off = xdp->data_end - orig_data_end;
 	if (off != 0)
 		__skb_put(skb, off); /* positive on grow, negative on shrink */
 
 	/* XDP frag metadata (e.g. nr_frags) are updated in eBPF helpers
 	 * (e.g. bpf_xdp_adjust_tail), we need to update data_len here.
 	 */
-	if (xdp_buff_has_frags(&xdp))
+	if (xdp_buff_has_frags(xdp))
 		skb->data_len = skb_shinfo(skb)->xdp_frags_size;
 	else
 		skb->data_len = 0;
 
 	skb->protocol = eth_type_trans(skb, rq->dev);
 
-	metalen = xdp.data - xdp.data_meta;
+	metalen = xdp->data - xdp->data_meta;
 	if (metalen)
 		skb_metadata_set(skb, metalen);
 out:
@@ -898,7 +904,7 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq,
 	return NULL;
 err_xdp:
 	rcu_read_unlock();
-	xdp_return_buff(&xdp);
+	xdp_return_buff(xdp);
 xdp_xmit:
 	return NULL;
 }