Re: [PATCH bpf-next v1 2/2] bpf: sockopt_sk: fix 'undeclared' definition error

[Jason Xing <kerneljasonxing@xxxxxxxxx>]

On Wed, Feb 5, 2025 at 10:57 AM Hou Tao <houtao@xxxxxxxxxxxxxxx> wrote:
>
> Hi,
>
> On 2/4/2025 10:39 AM, Jason Xing wrote:
> > Error messages:
> > selftests/bpf/prog_tests/sockopt_sk.c: In function ‘getsetsockopt’:
> > selftests/bpf/prog_tests/sockopt_sk.c:22:31: error: field ‘zc’ has incomplete type
> >    struct tcp_zerocopy_receive zc;
> >                                ^~
> > selftests/bpf/prog_tests/sockopt_sk.c:169:32: error: ‘TCP_ZEROCOPY_RECEIVE’ undeclared (first use in this function)
> >   err = getsockopt(fd, SOL_TCP, TCP_ZEROCOPY_RECEIVE, &buf, &optlen);
> >                                 ^~~~~~~~~~~~~~~~~~~~
> >
> > Fix it by introducing the right header.
> >
> > Signed-off-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
> > ---
> >  tools/testing/selftests/bpf/prog_tests/sockopt_sk.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
> > index ba6b3ec1156a..e0a9785ffcdc 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
> > @@ -2,7 +2,7 @@
> >  #include <test_progs.h>
> >  #include "cgroup_helpers.h"
> >
> > -#include <netinet/tcp.h>
> > +#include <uapi/linux/tcp.h>
>
> Should it be <linux/tcp.h> instead ?

I thought that too, but I altered my thoughts after reading this
commit[1], totally without knowing why the tcp part should be changed.
Should I change it back?

> Directly including uapi header file
> in application seems weird.

After greping the tools/testing/selftests/bpf, we see some similar
usage like including a uapi header file.

[1]
commit a2f482c34a52176ae89d143979bbc9e7a72857c8
Author: Alexis Lothoré (eBPF Foundation) <alexis.lothore@xxxxxxxxxxx>
Date:   Wed Nov 20 08:43:21 2024 +0100

    selftests/bpf: use the same udp and tcp headers in tests under test_progs

    Trying to add udp-dedicated helpers in network_helpers involves
    including some udp header, which makes multiple test_progs tests build
    fail:

    In file included from ./progs/test_cls_redirect.h:13,
                     from [...]/prog_tests/cls_redirect.c:15:
    [...]/usr/include/linux/udp.h:23:8: error: redefinition of ‘struct udphdr’
       23 | struct udphdr {
          |        ^~~~~~
    In file included from ./network_helpers.h:17,
                     from [...]/prog_tests/cls_redirect.c:13:
    [...]/usr/include/netinet/udp.h:55:8: note: originally defined here
       55 | struct udphdr
          |        ^~~~~~

    This error is due to struct udphdr being defined in both <linux/udp.h>
    and <netinet/udp.h>.

    Use only <netinet/udp.h> in every test. While at it, perform the same
    for tcp.h. For some tests, the change needs to be done in the eBPF
    program part as well, because of some headers sharing between both
    sides.

Thanks,
Jason