Re: [PATCH bpf-next] selftests/bpf: remove logic duplication in test_verifier.c

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

On Fri, Jul 12, 2019 at 6:57 AM Daniel Borkmann <daniel@iogearbox.net> wrote:
>
> On 07/12/2019 09:53 AM, Krzesimir Nowak wrote:
> > On Thu, Jul 11, 2019 at 4:43 PM Andrii Nakryiko
> > <andrii.nakryiko@gmail.com> wrote:
> >>
> >> On Thu, Jul 11, 2019 at 5:13 AM Krzesimir Nowak <krzesimir@kinvolk.io> wrote:
> >>>
> >>> On Thu, Jul 11, 2019 at 3:08 AM Andrii Nakryiko <andriin@fb.com> wrote:
> >>>>
> >>>> test_verifier tests can specify single- and multi-runs tests. Internally
> >>>> logic of handling them is duplicated. Get rid of it by making single run
> >>>> retval specification to be a first retvals spec.
> >>>>
> >>>> Cc: Krzesimir Nowak <krzesimir@kinvolk.io>
> >>>> Signed-off-by: Andrii Nakryiko <andriin@fb.com>
> >>>
> >>> Looks good, one nit below.
> >>>
> >>> Acked-by: Krzesimir Nowak <krzesimir@kinvolk.io>
> >>>
> >>>> ---
> >>>>  tools/testing/selftests/bpf/test_verifier.c | 37 ++++++++++-----------
> >>>>  1 file changed, 18 insertions(+), 19 deletions(-)
> >>>>
> >>>> diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> >>>> index b0773291012a..120ecdf4a7db 100644
> >>>> --- a/tools/testing/selftests/bpf/test_verifier.c
> >>>> +++ b/tools/testing/selftests/bpf/test_verifier.c
> >>>> @@ -86,7 +86,7 @@ struct bpf_test {
> >>>>         int fixup_sk_storage_map[MAX_FIXUPS];
> >>>>         const char *errstr;
> >>>>         const char *errstr_unpriv;
> >>>> -       uint32_t retval, retval_unpriv, insn_processed;
> >>>> +       uint32_t insn_processed;
> >>>>         int prog_len;
> >>>>         enum {
> >>>>                 UNDEF,
> >>>> @@ -95,16 +95,24 @@ struct bpf_test {
> >>>>         } result, result_unpriv;
> >>>>         enum bpf_prog_type prog_type;
> >>>>         uint8_t flags;
> >>>> -       __u8 data[TEST_DATA_LEN];
> >>>>         void (*fill_helper)(struct bpf_test *self);
> >>>>         uint8_t runs;
> >>>> -       struct {
> >>>> -               uint32_t retval, retval_unpriv;
> >>>> -               union {
> >>>> -                       __u8 data[TEST_DATA_LEN];
> >>>> -                       __u64 data64[TEST_DATA_LEN / 8];
> >>>> +       union {
> >>>> +               struct {
> >>>
> >>> Maybe consider moving the struct definition outside to further the
> >>> removal of the duplication?
> >>
> >> Can't do that because then retval/retval_unpriv/data won't be
> >> accessible as a normal field of struct bpf_test. It has to be in
> >> anonymous structs/unions, unfortunately.
> >>
> >
> > Ah, right.
> >
> > Meh.
> >
> > I tried something like this:
> >
> > #define BPF_DATA_STRUCT \
> >     struct { \
> >         uint32_t retval, retval_unpriv; \
> >         union { \
> >             __u8 data[TEST_DATA_LEN]; \
> >             __u64 data64[TEST_DATA_LEN / 8]; \
> >         }; \
> >     }
> >
> > and then:
> >
> >     union {
> >         BPF_DATA_STRUCT;
> >         BPF_DATA_STRUCT retvals[MAX_TEST_RUNS];
> >     };
> >
> > And that seems to compile at least. But question is: is this
> > acceptably ugly or unacceptably ugly? :)
>
> Both a bit ugly, but I'd have a slight preference towards the above,
> perhaps a bit more readable like:

Heh, I had slight preference the other way :) I'll update diff with
macro, though.

>
> #define bpf_testdata_struct_t                                   \
>         struct {                                                \
>                 uint32_t retval, retval_unpriv;                 \
>                 union {                                         \
>                         __u8 data[TEST_DATA_LEN];               \
>                         __u64 data64[TEST_DATA_LEN / 8];        \
>                 };                                              \
>         }
>         union {
>                 bpf_testdata_struct_t;
>                 bpf_testdata_struct_t retvals[MAX_TEST_RUNS];
>         };
>
> Thanks,
> Daniel