Re: [PATCH bpf-next v4 5/6] selftests/bpf: Fix error failure of case test_xdp_adjust_tail_grow

[Xu Kuohai]

On 10/13/2022 7:17 AM, Martin KaFai Lau wrote:
> On 10/11/22 5:01 AM, Xu Kuohai wrote:
> > From: Xu Kuohai <xukuohai@xxxxxxxxxx>
> >
> > test_xdp_adjust_tail_grow failed with ipv6:
> >    test_xdp_adjust_tail_grow:FAIL:ipv6 unexpected error: -28 (errno 28)
> >
> > The reason is that this test case tests ipv4 before ipv6, and when ipv4
> > test finished, topts.data_size_out was set to 54, which is smaller than the
> > ipv6 output data size 114, so ipv6 test fails with NOSPC error.
> >
> > Fix it by reset topts.data_size_out to sizeof(buf) before testing ipv6.
> >
> > Fixes: 04fcb5f9a104 ("selftests/bpf: Migrate from bpf_prog_test_run")
> > Signed-off-by: Xu Kuohai <xukuohai@xxxxxxxxxx>
> > ---
> >   tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c
> > index 9b9cf8458adf..009ee37607df 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c
> > @@ -63,6 +63,7 @@ static void test_xdp_adjust_tail_grow(void)
> >       expect_sz = sizeof(pkt_v6) + 40; /* Test grow with 40 bytes */
> >       topts.data_in = &pkt_v6;
> >       topts.data_size_in = sizeof(pkt_v6);
> > +    topts.data_size_out = sizeof(buf);
>
> lgtm but how was it working before... weird.

the test case returns before this line is executed, see patch 6

> >       err = bpf_prog_test_run_opts(prog_fd, &topts);
> >       ASSERT_OK(err, "ipv6");
> >       ASSERT_EQ(topts.retval, XDP_TX, "ipv6 retval");
>
> .