netdev - Re: [PATCH net-next v4 0/4] net: selftest: improve test string formatting and checksum handling

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Message-ID: <20250625132117.1b3264e8@kernel.org>
Date: Wed, 25 Jun 2025 13:21:17 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Oleksij Rempel <o.rempel@...gutronix.de>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Simon Horman
 <horms@...nel.org>, kernel@...gutronix.de, linux-kernel@...r.kernel.org,
 netdev@...r.kernel.org, Maxime Chevallier <maxime.chevallier@...tlin.com>
Subject: Re: [PATCH net-next v4 0/4] net: selftest: improve test string
 formatting and checksum handling

On Wed, 25 Jun 2025 07:07:42 +0200 Oleksij Rempel wrote:
> Hm... at least part of this behavior can be verified with self-tests:
> 
> - Send a TCP packet with an intentionally incorrect checksum,
>   ensuring its state is CHECKSUM_NONE so the transmit path doesn't change it.
> - Test if we receive this packet back via the PHY loopback.
>    - If received: The test checks the ip_summed status of the
>      received packet.
>       - A status of CHECKSUM_NONE indicates the hardware correctly passed
>         the packet up without validating it.

_NONE or _COMPLETE are both fine in this case.

>       - A status of CHECKSUM_UNNECESSARY indicates a failure, as the hardware
>         or driver incorrectly marked a bad checksum as good.
>    - If not received (after a timeout): The test then checks the device's
>      error statistics.
>       - If the rx_errors counter has incremented
>       - If the counter has not incremented, the packet was lost for an unknown
>         reason, and the test fails.
> 
> What do you think?

Sounds like a good idea! Not sure if I'd bother with the rx_error
handling. Hopefully the drivers can be configured to pass the packet
thru.