[PATCH v3 bpf-next 10/11] selftests/bpf: Add a new cgroup helper get_cgroup_hierarchy_id()

Yafang Shao
2023-10-29T06:15:04Z

A new cgroup helper function, get_cgroup1_hierarchy_id(), has been
introduced to obtain the ID of a cgroup1 hierarchy based on the provided
cgroup name. This cgroup name can be obtained from the /proc/self/cgroup
file.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
tools/testing/selftests/bpf/cgroup_helpers.c | 49 ++++++++++++++++++++++++++++
tools/testing/selftests/bpf/cgroup_helpers.h | 1 +
2 files changed, 50 insertions(+)

diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c
index 63bfa72..d75bb87 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.c
+++ b/tools/testing/selftests/bpf/cgroup_helpers.c
@@ -637,3 +637,52 @@ unsigned long long get_classid_cgroup_id(void)
format_classid_path(cgroup_workdir);
return get_cgroup_id_from_path(cgroup_workdir);
}
+
+/**
+ * get_cgroup1_hierarchy_id - Retrieves the ID of a cgroup1 hierarchy from the cgroup1 name
+ * @cgrp_name: The cgroup1 name, which can be retrieved from /proc/self/cgroup.
+ */
+int get_cgroup1_hierarchy_id(const char *cgrp_name)
+{
+ char *c, *c2, *c3, *c4;
+ bool found = false;
+ char line[1024];
+ FILE *file;
+ int i, id;
+
+ if (!cgrp_name)
+ return -1;
+
+ file = fopen("/proc/self/cgroup", "r");
+ if (!file) {
+ log_err("fopen /proc/self/cgroup");
+ return -1;
+ }
+
+ while (fgets(line, 1024, file)) {
+ i = 0;
+ for (c = strtok_r(line, ":", &c2); c && i < 2; c = strtok_r(NULL, ":", &c2)) {
+ if (i == 0) {
+ id = strtol(c, NULL, 10);
+ } else if (i == 1) {
+ if (!strcmp(c, cgrp_name)) {
+ found = true;
+ break;
+ }
+
+ /* Multiple subsystems may share one single mount point */
+ for (c3 = strtok_r(c, ",", &c4); c3;
+ c3 = strtok_r(NULL, ",", &c4)) {
+ if (!strcmp(c, cgrp_name)) {
+ found = true;
+ break;
+ }
+ }
+ }
+ i++;
+ }
+ if (found)
+ break;
+ }
+ return found ? id : -1;
+}
diff --git a/tools/testing/selftests/bpf/cgroup_helpers.h b/tools/testing/selftests/bpf/cgroup_helpers.h
index e71da4e..a80c417 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.h
+++ b/tools/testing/selftests/bpf/cgroup_helpers.h
@@ -20,6 +20,7 @@ int write_cgroup_file_parent(const char *relative_path, const char *file,
int create_and_get_cgroup(const char *relative_path);
void remove_cgroup(const char *relative_path);
unsigned long long get_cgroup_id(const char *relative_path);
+int get_cgroup1_hierarchy_id(const char *cgrp_name);

int join_cgroup(const char *relative_path);
int join_root_cgroup(void);
--
1.8.3.1