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Date:   Mon, 6 Nov 2023 15:43:30 +0200
From:   Vladimir Oltean <olteanv@gmail.com>
To:     Linus Walleij <linus.walleij@linaro.org>
Cc:     Hans Ulli Kroll <ulli.kroll@googlemail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= <mirq-linux@rere.qmqm.pl>,
        Andrew Lunn <andrew@lunn.ch>,
        linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH net v2 4/4] net: ethernet: cortina: Handle large frames
Message-ID: <20231106134330.nyxuayv5g6q4l43y@skbuf>
References: <20231105-gemini-largeframe-fix-v2-0-cd3a5aa6c496@linaro.org>
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 <20231105-gemini-largeframe-fix-v2-4-cd3a5aa6c496@linaro.org>
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On Mon, Nov 06, 2023 at 03:26:26PM +0200, Vladimir Oltean wrote:
> Gemini should never attempt to provide checksums for DSA-tagged packets
> unless it is able to take skb->csum_start into consideration, otherwise
> it will get it wrong.

Additionally, since Gemini does not put NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM
in vlan_features, DSA won't inherit (thus won't have) them. So,
validate_xmit_skb() should perform the skb checksum during the xmit on
the user port, which is earlier compared to the xmit on the conduit.
So, I guess skb->ip_summed should already be CHECKSUM_NONE here?
I think the only problem for DSA is the lack of the TSS_BYPASS_BIT. The
rest is unrelated.