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Date:   Mon, 29 Aug 2022 11:03:27 -0700
From:   Martin KaFai Lau <kafai@fb.com>
To:     James Hilliard <james.hilliard1@gmail.com>
Cc:     bpf@vger.kernel.org, Andrii Nakryiko <andrii@kernel.org>,
        Mykola Lysenko <mykolal@fb.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        Shuah Khan <shuah@kernel.org>, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] selftests/bpf: Fix bind{4,6} tcp/socket header type
 conflict
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On Sat, Aug 27, 2022 at 05:38:29AM -0600, James Hilliard wrote:
> On Fri, Aug 26, 2022 at 5:05 PM Martin KaFai Lau <kafai@fb.com> wrote:
> >
> > On Thu, Aug 25, 2022 at 11:29:22PM -0600, James Hilliard wrote:
> > > There is a potential for us to hit a type conflict when including
> > > netinet/tcp.h with sys/socket.h, we can remove these as they are not
> > > actually needed.
> > >
> > > Fixes errors like:
> > > In file included from /usr/include/netinet/tcp.h:91,
> > >                  from progs/bind4_prog.c:10:
> > > /home/buildroot/opt/cross/lib/gcc/bpf/13.0.0/include/stdint.h:34:23: error: conflicting types for 'int8_t'; have 'char'
> > >    34 | typedef __INT8_TYPE__ int8_t;
> > >       |                       ^~~~~~
> > > In file included from /usr/include/x86_64-linux-gnu/sys/types.h:155,
> > >                  from /usr/include/x86_64-linux-gnu/bits/socket.h:29,
> > >                  from /usr/include/x86_64-linux-gnu/sys/socket.h:33,
> > >                  from progs/bind4_prog.c:9:
> > > /usr/include/x86_64-linux-gnu/bits/stdint-intn.h:24:18: note: previous declaration of 'int8_t' with type 'int8_t' {aka 'signed char'}
> > >    24 | typedef __int8_t int8_t;
> > >       |                  ^~~~~~
> > > /home/buildroot/opt/cross/lib/gcc/bpf/13.0.0/include/stdint.h:43:24: error: conflicting types for 'int64_t'; have 'long int'
> > >    43 | typedef __INT64_TYPE__ int64_t;
> > >       |                        ^~~~~~~
> > > /usr/include/x86_64-linux-gnu/bits/stdint-intn.h:27:19: note: previous declaration of 'int64_t' with type 'int64_t' {aka 'long long int'}
> > >    27 | typedef __int64_t int64_t;
> > >       |                   ^~~~~~~
> > > make: *** [Makefile:537: /home/buildroot/bpf-next/tools/testing/selftests/bpf/bpf_gcc/bind4_prog.o] Error 1
> > >
> > > Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
> > > ---
> > > Changes v1 -> v2:
> > >   - just remove netinet/tcp.h and sys/socket.h
> > > ---
> > >  tools/testing/selftests/bpf/progs/bind4_prog.c | 2 --
> > >  tools/testing/selftests/bpf/progs/bind6_prog.c | 2 --
> > >  2 files changed, 4 deletions(-)
> > >
> > > diff --git a/tools/testing/selftests/bpf/progs/bind4_prog.c b/tools/testing/selftests/bpf/progs/bind4_prog.c
> > > index 474c6a62078a..a487f60b73ac 100644
> > > --- a/tools/testing/selftests/bpf/progs/bind4_prog.c
> > > +++ b/tools/testing/selftests/bpf/progs/bind4_prog.c
> > > @@ -6,8 +6,6 @@
> > >  #include <linux/bpf.h>
> > >  #include <linux/in.h>
> > >  #include <linux/in6.h>
> > > -#include <sys/socket.h>
> > > -#include <netinet/tcp.h>
> > >  #include <linux/if.h>
> > Are the AF_INET and SOCK_STREAM coming from linux/if.h somehow
> > and they are not from indirectly including sys/socket.h ?
> 
> Hmm, seems they are both coming from sys/socket.h:
> 
> Tests with my v2 patch applied:
> progs/bind4_prog.c:15: error: "AF_INET" redefined [-Werror]
>    15 | #define AF_INET nonsense
>       |
> In file included from /usr/include/x86_64-linux-gnu/sys/socket.h:33,
>                  from /usr/include/linux/if.h:28,
>                  from progs/bind4_prog.c:9:
> /usr/include/x86_64-linux-gnu/bits/socket.h:97: note: this is the
> location of the previous definition
>    97 | #define AF_INET         PF_INET
>       |
> 
> progs/bind4_prog.c:15: error: "SOCK_STREAM" redefined [-Werror]
>    15 | #define SOCK_STREAM nonsense
>       |
> In file included from /usr/include/x86_64-linux-gnu/bits/socket.h:38,
>                  from /usr/include/x86_64-linux-gnu/sys/socket.h:33,
>                  from /usr/include/linux/if.h:28,
>                  from progs/bind4_prog.c:9:
> /usr/include/x86_64-linux-gnu/bits/socket_type.h:28: note: this is the
> location of the previous definition
>    28 | #define SOCK_STREAM SOCK_STREAM
>       |
> 
> So I guess the problematic header is netinet/tcp.h and sys/socket.h is
> just a redundant include?
> 
> Removing just netinet/tcp.h does appear sufficient to fix the issue.
Yeah, it is what I am puzzled and getting at.
<sys/socket.h> is fine and <netinet/tcp.h> is not ok.
They are both from glibc ?  This kind of header changes
is hard to reason without doing the kind of experiment
that you just did.

> 
> >
> > If the program does not need if.h, what should it use ?
> > There are other progs in selftest/bpf that include sys/socket.h
> > and they have no issue ?
> 
> I'm still working through gcc issues with the test suite so there's
> probably some cases I haven't identified yet but this is the only one
> that seemed to need any code changes when removing those 2
> headers that I've found so far:
> https://lore.kernel.org/bpf/20220826055025.1018491-1-james.hilliard1@gmail.com/