Re: [PATCH -next v2] bpf/benchs: Fix return value check of bpf_program__attach()

[Yonghong Song]

On 11/1/21 3:00 PM, Alexei Starovoitov wrote:
> On Mon, Nov 1, 2021 at 5:35 AM Yang Yingliang <yangyingliang@xxxxxxxxxx> wrote:
> > If bpf_program__attach() fails, it never returns NULL,
> > we should use libbpf_get_error() to check the return value.
> >
> > Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> > Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
> > Acked-by: Yonghong Song <yhs@xxxxxx>
> > ---
> > v2:
> >    don't use 'int err'
> > ---
> >   .../selftests/bpf/benchs/bench_bloom_filter_map.c      | 10 +++++-----
> >   1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> > index 6eeeed2913e6..4afaa4adb327 100644
> > --- a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> > +++ b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> > @@ -304,7 +304,7 @@ static void bloom_lookup_setup(void)
> >          populate_maps();
> >
> >          link = bpf_program__attach(ctx.skel->progs.bloom_lookup);
> > -       if (!link) {
> > +       if (libbpf_get_error(link)) {
>
> Please use ASSERT_OK_PTR() instead.
> See how other tests are doing it.

I actually looked at this. ASSERT_OK_PTR() is defined in test_progs.h
and test_progs.h is ONLY included in files which eventually linked to
test_progs. That is why I didn't recommend to use ASSERT_OK_PTR().

Maybe it is okay to include test_progs.h in benchs/*.c. Or we may
want to refactor to a separate header file to contain these macros
which can be used for test_progs.h and other applications.

>