Re: [PATCH bpf-next] selftests/bpf: Mount debugfs in setns_by_fd

[Jiri Olsa <olsajiri@gmail.com>]

On Wed, Nov 23, 2022 at 12:08:29PM -0800, Stanislav Fomichev wrote:
> Jiri reports broken test_progs after recent commit 68f8e3d4b916
> ("selftests/bpf: Make sure zero-len skbs aren't redirectable").
> Apparently we don't remount debugfs when we switch back networking namespace.
> Let's explicitly mount /sys/kernel/debug.
> 
> 0: https://lore.kernel.org/bpf/63b85917-a2ea-8e35-620c-808560910819@meta.com/T/#ma66ca9c92e99eee0a25e40f422489b26ee0171c1
> 
> Fixes: a30338840fa5 ("selftests/bpf: Move open_netns() and close_netns() into network_helpers.c")
> Reported-by: Jiri Olsa <olsajiri@gmail.com>
> Signed-off-by: Stanislav Fomichev <sdf@google.com>

Acked-by: Jiri Olsa <olsajiri@gmail.com>
Tested-by: Jiri Olsa <olsajiri@gmail.com>

thanks,
jirka

> ---
>  tools/testing/selftests/bpf/network_helpers.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
> index bec15558fd93..1f37adff7632 100644
> --- a/tools/testing/selftests/bpf/network_helpers.c
> +++ b/tools/testing/selftests/bpf/network_helpers.c
> @@ -426,6 +426,10 @@ static int setns_by_fd(int nsfd)
>  	if (!ASSERT_OK(err, "mount /sys/fs/bpf"))
>  		return err;
>  
> +	err = mount("debugfs", "/sys/kernel/debug", "debugfs", 0, NULL);
> +	if (!ASSERT_OK(err, "mount /sys/kernel/debug"))
> +		return err;
> +
>  	return 0;
>  }
>  
> -- 
> 2.38.1.584.g0f3c55d4c2-goog
>