Re: [PATCH net-next 8/9] eth: fbnic: Collect packet statistics for XDP

[Simon Horman <horms@kernel.org>]

On Wed, Jul 23, 2025 at 07:59:25AM -0700, Mohsin Bashir wrote:
> Add support for XDP statistics collection and reporting via rtnl_link
> and netdev_queue API.
> 
> For XDP programs without frags support, fbnic requires MTU to be less
> than the HDS threshold. If an over-sized frame is received, the frame
> is dropped and recorded as rx_length_errors reported via ip stats to
> highlight that this is an error.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Mohsin Bashir <mohsin.bashr@gmail.com>
> ---
>  .../device_drivers/ethernet/meta/fbnic.rst    | 10 +++++
>  .../net/ethernet/meta/fbnic/fbnic_netdev.c    | 30 +++++++++++++
>  drivers/net/ethernet/meta/fbnic/fbnic_txrx.c  | 44 +++++++++++++++++--
>  drivers/net/ethernet/meta/fbnic/fbnic_txrx.h  |  1 +
>  4 files changed, 82 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/networking/device_drivers/ethernet/meta/fbnic.rst b/Documentation/networking/device_drivers/ethernet/meta/fbnic.rst
> index afb8353daefd..ad5e2cba7afc 100644
> --- a/Documentation/networking/device_drivers/ethernet/meta/fbnic.rst
> +++ b/Documentation/networking/device_drivers/ethernet/meta/fbnic.rst
> @@ -160,3 +160,13 @@ behavior and potential performance bottlenecks.
>  	  credit exhaustion
>          - ``pcie_ob_rd_no_np_cred``: Read requests dropped due to non-posted
>  	  credit exhaustion
> +
> +XDP Length Error:
> +~~~~~~~~~~~~~~~~~
> +
> +For XDP programs without frags support, fbnic tries to make sure that MTU fits
> +into a single buffer. If an oversized frame is received and gets fragmented,
> +it is dropped and the following netlink counters are updated
> +   - ``rx-length``: number of frames dropped due to lack of fragmentation
> +   support in the attached XDP program
> +   - ``rx-errors``: total number of packets with errors received on the interface

Hi Mohsin,

make hmtldocs complains a bit about this:

  .../fbnic.rst:170: ERROR: Unexpected indentation. [docutils]
  .../fbnic.rst:171: WARNING: Bullet list ends without a blank line; unexpected unindent. [docutils]

Empirically, and I admit there was much trial and error involved,
I was able to address this by:
* adding a blank before the start of the list
* updating the indentation of the follow-on line of the first entry of the list

Your mileage may vary.

diff --git a/Documentation/networking/device_drivers/ethernet/meta/fbnic.rst b/Documentation/networking/device_drivers/ethernet/meta/fbnic.rst
index ad5e2cba7afc..fb6559fa4be4 100644
--- a/Documentation/networking/device_drivers/ethernet/meta/fbnic.rst
+++ b/Documentation/networking/device_drivers/ethernet/meta/fbnic.rst
@@ -167,6 +167,7 @@ XDP Length Error:
 For XDP programs without frags support, fbnic tries to make sure that MTU fits
 into a single buffer. If an oversized frame is received and gets fragmented,
 it is dropped and the following netlink counters are updated
+
    - ``rx-length``: number of frames dropped due to lack of fragmentation
-   support in the attached XDP program
+     support in the attached XDP program
    - ``rx-errors``: total number of packets with errors received on the interface