netdev - Re: [PATCH 3/3] selftests: add a test for bpf_prog_test

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Date:   Tue, 20 Nov 2018 08:58:01 -0800
From:   Y Song <ys114321@...il.com>
To:     lmb@...udflare.com
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        netdev <netdev@...r.kernel.org>, linux-api@...r.kernel.org
Subject: Re: [PATCH 3/3] selftests: add a test for bpf_prog_test_run output size

On Tue, Nov 20, 2018 at 3:35 AM Lorenz Bauer <lmb@...udflare.com> wrote:
>
> On Sun, 18 Nov 2018 at 05:59, Y Song <ys114321@...il.com> wrote:
> >
> > On Fri, Nov 16, 2018 at 12:55 PM Lorenz Bauer <lmb@...udflare.com> wrote:
> > >
> > > Make sure that bpf_prog_test_run returns the correct length
> > > in the size_out argument and that the kernel respects the
> > > output size hint.
> > >
> > > Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
> > > ---
> > >  tools/testing/selftests/bpf/test_progs.c | 34 ++++++++++++++++++++++++
> > >  1 file changed, 34 insertions(+)
> > >
> > > diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
> > > index 560d7527b86b..6ab98e10e86f 100644
> > > --- a/tools/testing/selftests/bpf/test_progs.c
> > > +++ b/tools/testing/selftests/bpf/test_progs.c
> > > @@ -124,6 +124,39 @@ static void test_pkt_access(void)
> > >         bpf_object__close(obj);
> > >  }
> > >
> > > +static void test_output_size_hint(void)
> > > +{
> > > +       const char *file = "./test_pkt_access.o";
> > > +       struct bpf_object *obj;
> > > +       __u32 retval, size, duration;
> > > +       int err, prog_fd;
> > > +       char buf[10];
> > > +
> > > +       err = bpf_prog_load(file, BPF_PROG_TYPE_SCHED_CLS, &obj, &prog_fd);
> > > +       if (err) {
> > > +               error_cnt++;
> > > +               return;
> > > +       }
> > CHECK can also be used here.
> > if (CHECK(...)) {
> >    goto done;
> > }
> > where label "done" is right before bpf_object__close.
>
> I just copied this part from test_pkt_access, happy to change it though.
> However, I think "goto done" would lead to freeing an unallocated
> object in this case?

Right, you can just return here.

>
> --
> Lorenz Bauer  |  Systems Engineer
> 25 Lavington St., London SE1 0NZ
>
> www.cloudflare.com