bpf_cgroup_ancestor() allows BPF programs to access the ancestor of a
struct cgroup *. This patch adds selftests that validate its expected
behavior.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221122055458.173143-5-void@manifault.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>