Re: [PATCH net] selftests: drv-net: Check if combined-count exists

[David Wei <dw@davidwei.uk>]

On 2025-02-25 10:14, Joe Damato wrote:
> Some drivers, like tg3, do not set combined-count:
> 
> $ ethtool -l enp4s0f1
> Channel parameters for enp4s0f1:
> Pre-set maximums:
> RX:		4
> TX:		4
> Other:		n/a
> Combined:	n/a
> Current hardware settings:
> RX:		4
> TX:		1
> Other:		n/a
> Combined:	n/a
> 
> In the case where combined-count is not set, the ethtool netlink code
> in the kernel elides the value and the code in the test:
> 
>   netnl.channels_get(...)
> 
> With a tg3 device, the returned dictionary looks like:
> 
> {'header': {'dev-index': 3, 'dev-name': 'enp4s0f1'},
>  'rx-max': 4,
>  'rx-count': 4,
>  'tx-max': 4,
>  'tx-count': 1}
> 
> Note that the key 'combined-count' is missing. As a result of this
> missing key the test raises an exception:
> 
>  # Exception|     if channels['combined-count'] == 0:
>  # Exception|        ~~~~~~~~^^^^^^^^^^^^^^^^^^
>  # Exception| KeyError: 'combined-count'
> 
> Change the test to check if 'combined-count' is a key in the dictionary
> first and if not assume that this means the driver has separate RX and
> TX queues.
> 
> With this change, the test now passes successfully on tg3 and mlx5
> (which does have a 'combined-count').
> 
> Fixes: 1cf270424218 ("net: selftest: add test for netdev netlink queue-get API")
> Signed-off-by: Joe Damato <jdamato@fastly.com>
> ---
>  tools/testing/selftests/drivers/net/queues.py | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/drivers/net/queues.py b/tools/testing/selftests/drivers/net/queues.py
> index 38303da957ee..baa8845d9f64 100755
> --- a/tools/testing/selftests/drivers/net/queues.py
> +++ b/tools/testing/selftests/drivers/net/queues.py
> @@ -45,10 +45,13 @@ def addremove_queues(cfg, nl) -> None:
>  
>      netnl = EthtoolFamily()
>      channels = netnl.channels_get({'header': {'dev-index': cfg.ifindex}})
> -    if channels['combined-count'] == 0:
> -        rx_type = 'rx'
> +    if 'combined-count' in channels:
> +        if channels['combined-count'] == 0:
> +            rx_type = 'rx'
> +        else:
> +            rx_type = 'combined'
>      else:
> -        rx_type = 'combined'
> +        rx_type = 'rx'

Logic is good but minor nit in reducing nestiness:

rx_type = 'rx'
if channels.get('combined-count', 0) > 0:
	rx_type = 'combined'

>  
>      expected = curr_queues - 1
>      cmd(f"ethtool -L {cfg.dev['ifname']} {rx_type} {expected}", timeout=10)
> 
> base-commit: bc50682128bde778a1ddc457a02d92a637c20c6f