Re: [PATCH bpf-next v3 8/8] selftests/bpf: ringbuf_multi: use runtime page size

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Wed, Apr 7, 2021 at 11:05 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Wed, Apr 7, 2021 at 9:36 AM Yauheni Kaliuta
> <yauheni.kaliuta@redhat.com> wrote:
> >
> > Hi, Andrii!
> >
> > On Wed, Mar 31, 2021 at 9:52 PM Andrii Nakryiko
> > <andrii.nakryiko@gmail.com> wrote:
> > >
> > > On Wed, Mar 31, 2021 at 9:45 AM Yauheni Kaliuta
> > > <yauheni.kaliuta@redhat.com> wrote:
> > > >
> > > > Set bpf table sizes dynamically according to the runtime page size
> > > > value.
> > > >
> > > > Do not switch to ASSERT macros, keep CHECK, for consistency with the
> > > > rest of the test. Can be a separate cleanup patch.
> > > >
> > > > Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
> > > > ---
> > > >  .../selftests/bpf/prog_tests/ringbuf_multi.c  | 23 ++++++++++++++++---
> > > >  .../selftests/bpf/progs/test_ringbuf_multi.c  |  1 -
> > > >  2 files changed, 20 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
> > > > index d37161e59bb2..159de99621c7 100644
> > > > --- a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
> > > > +++ b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
> > > > @@ -41,13 +41,30 @@ static int process_sample(void *ctx, void *data, size_t len)
> > > >  void test_ringbuf_multi(void)
> > > >  {
> > > >         struct test_ringbuf_multi *skel;
> > > > -       struct ring_buffer *ringbuf;
> > > > +       struct ring_buffer *ringbuf = NULL;
> > > >         int err;
> > > > +       int page_size = getpagesize();
> > > >
> > > > -       skel = test_ringbuf_multi__open_and_load();
> > > > -       if (CHECK(!skel, "skel_open_load", "skeleton open&load failed\n"))
> > > > +       skel = test_ringbuf_multi__open();
> > > > +       if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
> > > >                 return;
> > > >
> > > > +       err = bpf_map__set_max_entries(skel->maps.ringbuf1, page_size);
> > > > +       if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
> > > > +               goto cleanup;
> > > > +
> > > > +       err = bpf_map__set_max_entries(skel->maps.ringbuf2, page_size);
> > > > +       if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
> > > > +               goto cleanup;
> > > > +
> > > > +       err = bpf_map__set_max_entries(bpf_map__inner_map(skel->maps.ringbuf_arr), page_size);
> > > > +       if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
> > > > +               goto cleanup;
> > > > +
> > > > +       err = test_ringbuf_multi__load(skel);
> > > > +       if (CHECK(err != 0, "skel_load", "skeleton load failed\n"))
> > > > +               goto cleanup;
> > > > +
> > >
> > > To test bpf_map__set_inner_map_fd() interaction with map-in-map
> > > initialization, can you extend the test to have another map-in-map
> > > (could be HASHMAP, just for fun), which is initialized with either
> > > ringbuf1 or ringbuf2, but then from user-space use a different way to
> > > override inner map definition:
> > >
> > > int proto_fd = bpf_create_map(... RINGBUF of page_size ...);
> > > bpf_map__set_inner_map_fd(skel->maps.ringbuf_hash, proto_fd);
> > > close(proto_fd);
> > >
> > > /* perform load, it should succeed */
> > >
> > > Important is to use a different map-in-map from ringbuf_arr, so that
> > > load fails, unless set_inner_map_fd() properly updates internals of a
> > > map.
> >
> > Is that what you mean?
>
> yes
>
>
> > https://github.com/ykaliuta/linux/commit/59fedd3b00678023d04b74bac61581a04896602e
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
> > b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
> > index 159de99621c7..5794317d05dd 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
> > @@ -44,6 +44,7 @@ void test_ringbuf_multi(void)
> >         struct ring_buffer *ringbuf = NULL;
> >         int err;
> >         int page_size = getpagesize();
> > +       int proto_fd;
> >
> >         skel = test_ringbuf_multi__open();
> >         if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
> > @@ -61,6 +62,16 @@ void test_ringbuf_multi(void)
> >         if (CHECK(err != 0, "bpf_map__set_max_entries",
> > "bpf_map__set_max_entries failed\n"))
> >                 goto cleanup;
> >
> > +       proto_fd = bpf_create_map(BPF_MAP_TYPE_RINGBUF, 0, 0, page_size, 0);
> > +       if (CHECK(proto_fd == -1, "bpf_create_map", "bpf_create_map failed\n"))
> > +               goto cleanup;
> > +
> > +       err = bpf_map__set_inner_map_fd(skel->maps.ringbuf_hash, proto_fd);
> > +       if (CHECK(err != 0, "bpf_map__set_inner_map_fd",
> > "bpf_map__set_inner_map_fd failed\n"))
> > +               goto cleanup;
> > +
> > +       close(proto_fd);

I think the problem is this, you are deleting that inner map too soon,
before the kernel can get it. Try moving close(proto_fd) after the
load step.

> > +
> >         err = test_ringbuf_multi__load(skel);
> >         if (CHECK(err != 0, "skel_load", "skeleton load failed\n"))
> >                 goto cleanup;
> > diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
> > b/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
> > index 055c10b2ff80..197b86546dca 100644
> > --- a/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
> > +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
> > @@ -30,6 +30,17 @@ struct {
> >         },
> >  };
> >
> > +struct {
> > +       __uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
> > +       __uint(max_entries, 1);
> > +       __type(key, int);
> > +       __array(values, struct ringbuf_map);
> > +} ringbuf_hash SEC(".maps") = {
> > +       .values = {
> > +               [0] = &ringbuf1,
> > +       },
> > +};
> > +
> >
> >
> > I get with it:
> >
> > test_ringbuf_multi:PASS:bpf_map__set_inner_map_fd 0 nsec
> > libbpf: Error in bpf_create_map_xattr(ringbuf_arr):Invalid
> > argument(-22). Retrying without BTF.
> > libbpf: Error in bpf_create_map_xattr(ringbuf_hash):Invalid
> > argument(-22). Retrying without BTF.
> > libbpf: map 'ringbuf_hash': failed to create: Invalid argument(-22)
> > libbpf: failed to load object 'test_ringbuf_multi'
> > libbpf: failed to load BPF skeleton 'test_ringbuf_multi': -22
> > test_ringbuf_multi:FAIL:skel_load skeleton load failed
> > #90 ringbuf_multi:FAIL
>
> Did you try to investigate why it doesn't work?
>
> >
> >
> > >
> > > >         /* only trigger BPF program for current process */
> > > >         skel->bss->pid = getpid();
> > > >
> > > > diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c b/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
> > > > index edf3b6953533..055c10b2ff80 100644
> > > > --- a/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
> > > > +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
> > > > @@ -15,7 +15,6 @@ struct sample {
> > > >
> > > >  struct ringbuf_map {
> > > >         __uint(type, BPF_MAP_TYPE_RINGBUF);
> > > > -       __uint(max_entries, 1 << 12);
> > > >  } ringbuf1 SEC(".maps"),
> > > >    ringbuf2 SEC(".maps");
> > > >
> > > > --
> > > > 2.31.1
> > > >
> > >
> >
> >
> > --
> > WBR, Yauheni
> >