netdev - [PATCH net 2/4] virtio-net: remove redundant truesize check with PAGE

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Message-ID: <20250625160849.61344-3-minhquangbui99@gmail.com>
Date: Wed, 25 Jun 2025 23:08:47 +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>,
	Stanislav Fomichev <sdf@...ichev.me>,
	virtualization@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org,
	Bui Quang Minh <minhquangbui99@...il.com>
Subject: [PATCH net 2/4] virtio-net: remove redundant truesize check with PAGE_SIZE

The truesize is guaranteed not to exceed PAGE_SIZE in
get_mergeable_buf_len(). It is saved in mergeable context, which is not
changeable by the host side, so the check in receive path is quite
redundant.

Signed-off-by: Bui Quang Minh <minhquangbui99@...il.com>
---
 drivers/net/virtio_net.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 2a130a3e50ac..6f9fedad4a5e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2144,9 +2144,9 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
 {
 	struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
 	unsigned int headroom, tailroom, room;
-	unsigned int truesize, cur_frag_size;
 	struct skb_shared_info *shinfo;
 	unsigned int xdp_frags_truesz = 0;
+	unsigned int truesize;
 	struct page *page;
 	skb_frag_t *frag;
 	int offset;
@@ -2194,9 +2194,8 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
 		tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
 		room = SKB_DATA_ALIGN(headroom + tailroom);
 
-		cur_frag_size = truesize;
-		xdp_frags_truesz += cur_frag_size;
-		if (unlikely(len > truesize - room || cur_frag_size > PAGE_SIZE)) {
+		xdp_frags_truesz += truesize;
+		if (unlikely(len > truesize - room)) {
 			put_page(page);
 			pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
 				 dev->name, len, (unsigned long)(truesize - room));
-- 
2.43.0