[PATCH v4 bpf-next 3/4] selftests/bpf: enable all available cgroup v2 controllers

From: Roman Gushchin
Date: Fri May 24 2019 - 19:55:19 EST


Enable all available cgroup v2 controllers when setting up
the environment for the bpf kselftests. It's required to properly test
the bpf prog auto-detach feature. Also it will generally increase
the code coverage.

Signed-off-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
---
tools/testing/selftests/bpf/cgroup_helpers.c | 57 ++++++++++++++++++++
1 file changed, 57 insertions(+)

diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c
index 6692a40a6979..0d89f0396be4 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.c
+++ b/tools/testing/selftests/bpf/cgroup_helpers.c
@@ -33,6 +33,60 @@
snprintf(buf, sizeof(buf), "%s%s%s", CGROUP_MOUNT_PATH, \
CGROUP_WORK_DIR, path)

+/**
+ * enable_all_controllers() - Enable all available cgroup v2 controllers
+ *
+ * Enable all available cgroup v2 controllers in order to increase
+ * the code coverage.
+ *
+ * If successful, 0 is returned.
+ */
+int enable_all_controllers(char *cgroup_path)
+{
+ char path[PATH_MAX + 1];
+ char buf[PATH_MAX];
+ char *c, *c2;
+ int fd, cfd;
+ size_t len;
+
+ snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path);
+ fd = open(path, O_RDONLY);
+ if (fd < 0) {
+ log_err("Opening cgroup.controllers: %s", path);
+ return 1;
+ }
+
+ len = read(fd, buf, sizeof(buf) - 1);
+ if (len < 0) {
+ close(fd);
+ log_err("Reading cgroup.controllers: %s", path);
+ return 1;
+ }
+ buf[len] = 0;
+ close(fd);
+
+ /* No controllers available? We're probably on cgroup v1. */
+ if (len == 0)
+ return 0;
+
+ snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
+ cfd = open(path, O_RDWR);
+ if (cfd < 0) {
+ log_err("Opening cgroup.subtree_control: %s", path);
+ return 1;
+ }
+
+ for (c = strtok_r(buf, " ", &c2); c; c = strtok_r(NULL, " ", &c2)) {
+ if (dprintf(cfd, "+%s\n", c) <= 0) {
+ log_err("Enabling controller %s: %s", c, path);
+ close(cfd);
+ return 1;
+ }
+ }
+ close(cfd);
+ return 0;
+}
+
/**
* setup_cgroup_environment() - Setup the cgroup environment
*
@@ -71,6 +125,9 @@ int setup_cgroup_environment(void)
return 1;
}

+ if (enable_all_controllers(cgroup_workdir))
+ return 1;
+
return 0;
}

--
2.21.0