[PATCH net v2 2/3] virtio-net: remove redundant truesize check with PAGE_SIZE

From: Bui Quang Minh
Date: Mon Jun 30 2025 - 10:47:51 EST


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.

Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Signed-off-by: Bui Quang Minh <minhquangbui99@xxxxxxxxx>
---
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 31661bcb3932..535a4534c27f 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2157,9 +2157,9 @@ 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;
@@ -2207,9 +2207,8 @@ 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