netdev: clarify GSO vs csum in qstats

Could be just me, but I had to pause and double check that the Tx csum
counter in qstat should include GSO'd packets. GSO pretty much implies
csum so one could possibly interpret the csum counter as pure csum offload.

But the counters are based on virtio:

  [tx_needs_csum]
      The number of packets which require checksum calculation by the device.

  [rx_needs_csum]
      The number of packets with VIRTIO_NET_HDR_F_NEEDS_CSUM.

and VIRTIO_NET_HDR_F_NEEDS_CSUM gets set on GSO packets virtio sends.

Clarify this in the spec to avoid any confusion.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250214224601.2271201-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index 85402a2e289c409b36ddfbcb52c9ae26c6ea9938..766b82005d1840dc4d7ca4b9ed91e21d5fd88234 100644 (file)
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -467,6 +467,8 @@ attribute-sets:
         name: tx-needs-csum
         doc: |
           Number of packets that required the device to calculate the checksum.
+          This counter includes the number of GSO wire packets for which device
+          calculated the L4 checksum.
         type: uint
       -
         name: tx-hw-gso-packets