[PATCH net-next 3/4] tools/testing/selftests/cgroup/cgroup_util: add cg_get_id helper

[Alexander Mikhalitsyn]

Cc: linux-kselftest@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Cc: cgroups@xxxxxxxxxxxxxxx
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: Willem de Bruijn <willemb@xxxxxxxxxx>
Cc: Leon Romanovsky <leon@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Cc: Lennart Poettering <mzxreary@xxxxxxxxxxx>
Cc: Luca Boccassi <bluca@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: "Michal Koutný" <mkoutny@xxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
---
 tools/testing/selftests/cgroup/cgroup_util.c | 15 +++++++++++++++
 tools/testing/selftests/cgroup/cgroup_util.h |  2 ++
 2 files changed, 17 insertions(+)

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index 1e2d46636a0c..b60e0e1433f4 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -205,6 +205,21 @@ int cg_open(const char *cgroup, const char *control, int flags)
 	return open(path, flags);
 }
 
+/*
+ * Returns cgroup id on success, or -1 on failure.
+ */
+uint64_t cg_get_id(const char *cgroup)
+{
+	struct stat st;
+	int ret;
+
+	ret = stat(cgroup, &st);
+	if (ret)
+		return -1;
+
+	return st.st_ino;
+}
+
 int cg_write_numeric(const char *cgroup, const char *control, long value)
 {
 	char buf[64];
diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h
index 19b131ee7707..3f2d9676ceda 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.h
+++ b/tools/testing/selftests/cgroup/cgroup_util.h
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <stdbool.h>
+#include <stdint.h>
 #include <stdlib.h>
 
 #include "../kselftest.h"
@@ -39,6 +40,7 @@ long cg_read_key_long(const char *cgroup, const char *control, const char *key);
 extern long cg_read_lc(const char *cgroup, const char *control);
 extern int cg_write(const char *cgroup, const char *control, char *buf);
 extern int cg_open(const char *cgroup, const char *control, int flags);
+extern uint64_t cg_get_id(const char *cgroup);
 int cg_write_numeric(const char *cgroup, const char *control, long value);
 extern int cg_run(const char *cgroup,
 		  int (*fn)(const char *cgroup, void *arg),
-- 
2.43.0