netdev - Re: [PATCH net] selftests/net: fixes psock

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Date:   Wed, 14 Feb 2018 12:34:13 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Prashant Bhole <bhole_prashant_q7@....ntt.co.jp>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Shuah Khan <shuah@...nel.org>,
        Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH net] selftests/net: fixes psock_fanout eBPF test case

On Wed, Feb 14, 2018 at 2:00 AM, Prashant Bhole
<bhole_prashant_q7@....ntt.co.jp> wrote:
> eBPF test fails due to verifier failure because log_buf is too small
>
> Fixed by increasing log_buf size
>
> Signed-off-by: Prashant Bhole <bhole_prashant_q7@....ntt.co.jp>
> ---
>  tools/testing/selftests/net/psock_fanout.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/net/psock_fanout.c b/tools/testing/selftests/net/psock_fanout.c
> index 989f917068d1..898278a41322 100644
> --- a/tools/testing/selftests/net/psock_fanout.c
> +++ b/tools/testing/selftests/net/psock_fanout.c
> @@ -140,7 +140,7 @@ static void sock_fanout_set_ebpf(int fd)
>                 { BPF_ALU   | BPF_MOV | BPF_K,   0, 0, 0, 0 },
>                 { BPF_JMP   | BPF_EXIT,          0, 0, 0, 0 }
>         };
> -       char log_buf[512];
> +       char log_buf[65536];

Please don't allocate that much on the stack. Since this is a single
threaded test, it is okay to statically allocate. See for instance
reuseport_bpf.c

Thanks for sending a patch. I could reproduce the issue.