netdev - Re: [PATCHv2 net-next 02/17] udp6: move the mss check after udp gso tunnel processing

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Message-ID: <CA+FuTScNHkYu2F2xPBjLj9ivfLRXVbTPypgjvtEZrebatpJJfQ@mail.gmail.com>
Date:   Thu, 8 Oct 2020 08:44:36 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Xin Long <lucien.xin@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        Michael Tuexen <tuexen@...muenster.de>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCHv2 net-next 02/17] udp6: move the mss check after udp gso
 tunnel processing

On Thu, Oct 8, 2020 at 5:48 AM Xin Long <lucien.xin@...il.com> wrote:
>
> For some protocol's gso, like SCTP, it's using GSO_BY_FRAGS for
> gso_size. When using UDP to encapsulate its packet, it will
> return error in udp6_ufo_fragment() as skb->len < gso_size,
> and it will never go to the gso tunnel processing.
>
> So we should move this check after udp gso tunnel processing,
> the same as udp4_ufo_fragment() does. While at it, also tidy
> the variables up.

Please don't mix a new feature and code cleanup.

This patch changes almost every line of the function due to
indentation changes. But the only relevant part is

"
        mss = skb_shinfo(skb)->gso_size;
        if (unlikely(skb->len <= mss))
                goto out;

        if (skb->encapsulation && skb_shinfo(skb)->gso_type &
            (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
                segs = skb_udp_tunnel_segment(skb, features, true);
        else {
                /* irrelevant here */
        }

out:
        return segs;
}
"

Is it a sufficient change to just skip the mss check if mss == GSO_BY_FRAGS?