perf tools: Add cgroup_is_v2() helper
The cgroup_is_v2() is to check if the given subsystem is mounted on
cgroup v2 or not. It'll be used by BPF cgroup code later.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20210625071826.608504-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/cgroup.h b/tools/perf/util/cgroup.h
index f3c9787..de5b272 100644
--- a/tools/perf/util/cgroup.h
+++ b/tools/perf/util/cgroup.h
@@ -48,4 +48,6 @@ static inline int read_cgroup_id(struct cgroup *cgrp __maybe_unused)
}
#endif /* HAVE_FILE_HANDLE */
+int cgroup_is_v2(const char *subsys);
+
#endif /* __CGROUP_H__ */
