Re: [PATCH v2] selftests/bpf: Fix bind{4,6} tcp/socket header type conflict

[James Hilliard]

On Fri, Aug 26, 2022 at 5:05 PM Martin KaFai Lau <kafai@xxxxxx> 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@xxxxxxxxx>
> > ---
> > 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.

>
> 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@xxxxxxxxx/