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

[Martin KaFai Lau <martin.lau@linux.dev>]

On 10/11/22 5:01 AM, Xu Kuohai wrote:
> From: Xu Kuohai <xukuohai@huawei.com>
> 
> 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@huawei.com>
> ---
>   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.

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