[PATCH 6.12 162/169] vsock/virtio: Move length check to callers of virtio_vsock_skb_rx_put()

Greg Kroah-Hartman
2026-01-28T15:49:37Z

From: Will Deacon <will@kernel.org>

[Upstream commit 87dbae5e36613a6020f3d64a2eaeac0a1e0e6dc6]

virtio_vsock_skb_rx_put() only calls skb_put() if the length in the
packet header is not zero even though skb_put() handles this case
gracefully.

Remove the functionally redundant check from virtio_vsock_skb_rx_put()
and, on the assumption that this is a worthwhile optimisation for
handling credit messages, augment the existing length checks in
virtio_transport_rx_work() to elide the call for zero-length payloads.
Since the callers all have the length, extend virtio_vsock_skb_rx_put()
to take it as an additional parameter rather than fish it back out of
the packet header.

Note that the vhost code already has similar logic in
vhost_vsock_alloc_skb().

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Will Deacon <will@kernel.org>
Message-Id: <20250717090116.11987-4-will@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Heitor Alves de Siqueira <halves@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/vhost/vsock.c | 2 +-
include/linux/virtio_vsock.h | 9 ++-------
net/vmw_vsock/virtio_transport.c | 4 +++-
3 files changed, 6 insertions(+), 9 deletions(-)

--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -376,7 +376,7 @@ vhost_vsock_alloc_skb(struct vhost_virtq
return NULL;
}

- virtio_vsock_skb_rx_put(skb);
+ virtio_vsock_skb_rx_put(skb, payload_len);

nbytes = copy_from_iter(skb->data, payload_len, &iov_iter);
if (nbytes != payload_len) {
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -47,14 +47,9 @@ static inline void virtio_vsock_skb_clea
VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = false;
}

-static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb)
+static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb, u32 len)
{
- u32 len;
-
- len = le32_to_cpu(virtio_vsock_hdr(skb)->len);
-
- if (len > 0)
- skb_put(skb, len);
+ skb_put(skb, len);
}

static inline struct sk_buff *virtio_vsock_alloc_skb(unsigned int size, gfp_t mask)
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -656,7 +656,9 @@ static void virtio_transport_rx_work(str
continue;
}

- virtio_vsock_skb_rx_put(skb);
+ if (payload_len)
+ virtio_vsock_skb_rx_put(skb, payload_len);
+
virtio_transport_deliver_tap_pkt(skb);
virtio_transport_recv_pkt(&virtio_transport, skb);
}