Re: [PATCH bpf-next] selftests/bpf: bring back (void *) cast to set_ipv4_csum in test_tc_tunnel

From: Song Liu <liu.song.a23@gmail.com>
To: Stanislav Fomichev <sdf@google.com>
Cc: Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Alan Maguire <alan.maguire@oracle.com>,
	Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Subject: Re: [PATCH bpf-next] selftests/bpf: bring back (void *) cast to set_ipv4_csum in test_tc_tunnel
Date: Thu, 11 Apr 2019 23:01:01 -0700	[thread overview]
Message-ID: <CAPhsuW7a0XxoFF0V5TFRYqAKHu9_d0gfYGTnfTcEWch1sTBung@mail.gmail.com> (raw)
In-Reply-To: <20190411225316.125106-1-sdf@google.com>

On Thu, Apr 11, 2019 at 4:08 PM Stanislav Fomichev <sdf@google.com> wrote:
>
> It was removed in commit 166b5a7f2ca3 ("selftests_bpf: extend
> test_tc_tunnel for UDP encap") without any explanation.
>
> Otherwise I see:
> progs/test_tc_tunnel.c:160:17: warning: taking address of packed member 'ip' of class or structure
>       'v4hdr' may result in an unaligned pointer value [-Waddress-of-packed-member]
>         set_ipv4_csum(&h_outer.ip);
>                        ^~~~~~~~~~
> 1 warning generated.
>
> Cc: Alan Maguire <alan.maguire@oracle.com>
> Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> Fixes: 166b5a7f2ca3 ("selftests_bpf: extend test_tc_tunnel for UDP encap")
> Signed-off-by: Stanislav Fomichev <sdf@google.com>

Acked-by: Song Liu <songliubraving@fb.com>

> ---
>  tools/testing/selftests/bpf/progs/test_tc_tunnel.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
> index bcb00d737e95..ab56a6a72b7a 100644
> --- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
> +++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
> @@ -157,7 +157,7 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
>                                        bpf_ntohs(h_outer.ip.tot_len));
>         h_outer.ip.protocol = encap_proto;
>
> -       set_ipv4_csum(&h_outer.ip);
> +       set_ipv4_csum((void *)&h_outer.ip);
>
>         /* store new outer network header */
>         if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
> --
> 2.21.0.392.gf8f6787159e-goog
>