selftests/bpf: extend cgroup helpers

This patch extends bpf selft cgroup_helpers [ID] n various ways:
- Add enable_controllers() that allows tests to enable all or a
  subset of controllers for a specific cgroup.
- Add join_cgroup_parent(). The cgroup workdir is based on the pid,
  therefore a spawned child cannot join the same cgroup hierarchy of the
  test through join_cgroup(). join_cgroup_parent() is used in child
  processes to join a cgroup under the parent's workdir.
- Add write_cgroup_file() and write_cgroup_file_parent() (similar to
  join_cgroup_parent() above).
- Add get_root_cgroup() for tests that need to do checks on root cgroup.
- Distinguish relative and absolute cgroup paths in function arguments.
  Now relative paths are called relative_path, and absolute paths are
  called cgroup_path.

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220824233117.1312810-5-haoluo@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 13 insertions, 6 deletions

diff --git a/tools/testing/selftests/bpf/cgroup_helpers.h b/tools/testing/selftests/bpf/cgroup_helpers.h
index fcc9cb91b211..3358734356ab 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.h
+++ b/tools/testing/selftests/bpf/cgroup_helpers.h
@@ -10,11 +10,18 @@
 	__FILE__, __LINE__, clean_errno(), ##__VA_ARGS__)
 
 /* cgroupv2 related */
-int cgroup_setup_and_join(const char *path);
-int create_and_get_cgroup(const char *path);
-unsigned long long get_cgroup_id(const char *path);
-
-int join_cgroup(const char *path);
+int enable_controllers(const char *relative_path, const char *controllers);
+int write_cgroup_file(const char *relative_path, const char *file,
+		      const char *buf);
+int write_cgroup_file_parent(const char *relative_path, const char *file,
+			     const char *buf);
+int cgroup_setup_and_join(const char *relative_path);
+int get_root_cgroup(void);
+int create_and_get_cgroup(const char *relative_path);
+unsigned long long get_cgroup_id(const char *relative_path);
+
+int join_cgroup(const char *relative_path);
+int join_parent_cgroup(const char *relative_path);
 
 int setup_cgroup_environment(void);
 void cleanup_cgroup_environment(void);
@@ -26,4 +33,4 @@ int join_classid(void);
 int setup_classid_environment(void);
 void cleanup_classid_environment(void);
 
-#endif /* __CGROUP_HELPERS_H */
\ No newline at end of file
+#endif /* __CGROUP_HELPERS_H */