netdev - Re: [PATCH v5 net-next 02/13] net: allow gso_max

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Date:   Mon, 9 May 2022 19:09:04 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     kernel test robot <lkp@...el.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, kbuild-all@...ts.01.org,
        netdev <netdev@...r.kernel.org>,
        Alexander Duyck <alexanderduyck@...com>,
        Coco Li <lixiaoyan@...gle.com>
Subject: Re: [PATCH v5 net-next 02/13] net: allow gso_max_size to exceed 65536

On Mon, May 9, 2022 at 6:36 PM kernel test robot <lkp@...el.com> wrote:
>
> Hi Eric,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on net-next/master]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/Eric-Dumazet/tcp-BIG-TCP-implementation/20220510-062530
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 9c095bd0d4c451d31d0fd1131cc09d3b60de815d
> config: um-i386_defconfig (https://download.01.org/0day-ci/archive/20220510/202205100923.RHeXqtNd-lkp@intel.com/config)
> compiler: gcc-11 (Debian 11.2.0-20) 11.2.0
> reproduce (this is a W=1 build):
>         # https://github.com/intel-lab-lkp/linux/commit/8f9b47ee99f57d1747010d002315092bfa17ed50
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review Eric-Dumazet/tcp-BIG-TCP-implementation/20220510-062530
>         git checkout 8f9b47ee99f57d1747010d002315092bfa17ed50
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
>
> All errors (new ones prefixed by >>):
>
>    In file included from include/net/inet_sock.h:22,
>                     from include/net/ip.h:29,
>                     from include/linux/errqueue.h:6,
>                     from net/core/sock.c:91:
>    net/core/sock.c: In function 'sk_setup_caps':
> >> include/net/sock.h:389:37: error: 'struct sock_common' has no member named 'skc_v6_rcv_saddr'; did you mean 'skc_rcv_saddr'?
>      389 | #define sk_v6_rcv_saddr __sk_common.skc_v6_rcv_saddr
>          |                                     ^~~~~~~~~~~~~~~~
>    net/core/sock.c:2317:72: note: in expansion of macro 'sk_v6_rcv_saddr'
>     2317 |                              !sk_is_tcp(sk) || ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)))
>          |                                                                        ^~~~~~~~~~~~~~~
>
>

Alexander used :

+                       if (sk->sk_gso_max_size > GSO_LEGACY_MAX_SIZE &&
+                           (!IS_ENABLED(CONFIG_IPV6) || sk->sk_family
!= AF_INET6 ||
+                            !sk_is_tcp(sk) ||
ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)))
+                               sk->sk_gso_max_size = GSO_LEGACY_MAX_SIZE;

I guess we could simply allow gso_max_size to be bigger than
GSO_LEGACY_MAX_SIZE only
if IS_ENABLED(CONFIG_IPV6)

So the above code could really be:

#if IS_ENABLED(CONFIG_IPV6)
                       if (sk->sk_gso_max_size > GSO_LEGACY_MAX_SIZE &&
                           (sk->sk_family != AF_INET6 ||
                            !sk_is_tcp(sk) ||
ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)))
                               sk->sk_gso_max_size = GSO_LEGACY_MAX_SIZE;
#endif