linux-kernel - [PATCH net 2/2] virtio-net: xsk: rx: move the xdp->data adjustment to buf_to

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Message-ID: <20250615151333.10644-3-minhquangbui99@gmail.com>
Date: Sun, 15 Jun 2025 22:13:33 +0700
From: Bui Quang Minh <minhquangbui99@...il.com>
To: netdev@...r.kernel.org
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	virtualization@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org,
	Bui Quang Minh <minhquangbui99@...il.com>
Subject: [PATCH net 2/2] virtio-net: xsk: rx: move the xdp->data adjustment to buf_to_xdp()

This commit does not do any functional changes. It moves xdp->data
adjustment for buffer other than first buffer to buf_to_xdp() helper so
that the xdp_buff adjustment does not scatter over different functions.

Signed-off-by: Bui Quang Minh <minhquangbui99@...il.com>
---
 drivers/net/virtio_net.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7c9cf5ed1827..678502aefddd 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1167,7 +1167,19 @@ static struct xdp_buff *buf_to_xdp(struct virtnet_info *vi,
 		return NULL;
 	}
 
-	xsk_buff_set_size(xdp, len);
+	if (first_buf) {
+		xsk_buff_set_size(xdp, len);
+	} else {
+		/* This is the same as xsk_buff_set_size but with the adjusted
+		 * xdp->data.
+		 */
+		xdp->data = xdp->data_hard_start + XDP_PACKET_HEADROOM;
+		xdp->data -= vi->hdr_len;
+		xdp->data_meta = xdp->data;
+		xdp->data_end = xdp->data + len;
+		xdp->flags = 0;
+	}
+
 	xsk_buff_dma_sync_for_cpu(xdp);
 
 	return xdp;
@@ -1292,7 +1304,7 @@ static int xsk_append_merge_buffer(struct virtnet_info *vi,
 			goto err;
 		}
 
-		memcpy(buf, xdp->data - vi->hdr_len, len);
+		memcpy(buf, xdp->data, len);
 
 		xsk_buff_free(xdp);
 
-- 
2.43.0