selftests/cgroup: add tests for cloning into cgroups

Expand the cgroup test-suite to include tests for CLONE_INTO_CGROUP.
This adds the following tests:
- CLONE_INTO_CGROUP manages to clone a process directly into a correctly
  delegated cgroup
- CLONE_INTO_CGROUP fails to clone a process into a cgroup that has been
  removed after we've opened an fd to it
- CLONE_INTO_CGROUP fails to clone a process into an invalid domain
  cgroup
- CLONE_INTO_CGROUP adheres to the no internal process constraint
- CLONE_INTO_CGROUP works with the freezer feature

Cc: Tejun Heo <tj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: cgroups@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h
index 49c54fbdb229..5a1305dd1f0b 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.h
+++ b/tools/testing/selftests/cgroup/cgroup_util.h
@@ -50,3 +50,7 @@ extern int cg_wait_for_proc_count(const char *cgroup, int count);
 extern int cg_killall(const char *cgroup);
 extern ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t size);
 extern int proc_read_strstr(int pid, bool thread, const char *item, const char *needle);
+extern pid_t clone_into_cgroup(int cgroup_fd);
+extern int clone_reap(pid_t pid, int options);
+extern int clone_into_cgroup_run_wait(const char *cgroup);
+extern int dirfd_open_opath(const char *dir);