netdev - Re: [PATCH bpf-next v9 0/9] bpf: getsockopt and setsockopt hooks

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Date:   Thu, 27 Jun 2019 15:46:16 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Stanislav Fomichev <sdf@...ichev.me>
Cc:     Stanislav Fomichev <sdf@...gle.com>,
        Network Development <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [PATCH bpf-next v9 0/9] bpf: getsockopt and setsockopt hooks

On Thu, Jun 27, 2019 at 3:43 PM Stanislav Fomichev <sdf@...ichev.me> wrote:
>
> > There is a build warning though:
> > test_sockopt_sk.c: In function ‘getsetsockopt’:
> > test_sockopt_sk.c:115:2: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
> >   if (*(__u32 *)buf != 0x55AA*2) {
> >   ^~
> > test_sockopt_sk.c:116:3: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
> >    log_err("Unexpected getsockopt(SO_SNDBUF) 0x%x != 0x55AA*2",
> >    ^~~~~~~
> >
> > Pls fix it in the follow up.
> Sure, but I can't reproduce it with gcc7 nor with clang9 :-/

I see it with gcc 6.3