selftests/bpf: fix incorrect users of create_and_get_cgroup

We have some tests that assume create_and_get_cgroup returns -1 on error
which is incorrect (it returns 0 on error). Since fd might be zero in
general case, change create_and_get_cgroup to return -1 on error
and fix the users that assume 0 on error.

Fixes: f269099a7e7a ("tools/bpf: add a selftest for bpf_get_current_cgroup_id() helper")
Fixes: 7d2c6cfc5411 ("bpf: use --cgroup in test_suite if supplied")

v2:
- instead of fixing the uses that assume -1 on error, convert the users
  that assume 0 on error (fd might be zero in general case)

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c
index cf16948aad4a..6692a40a6979 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.c
+++ b/tools/testing/selftests/bpf/cgroup_helpers.c
@@ -155,7 +155,7 @@ void cleanup_cgroup_environment(void)
  * This function creates a cgroup under the top level workdir and returns the
  * file descriptor. It is idempotent.
  *
- * On success, it returns the file descriptor. On failure it returns 0.
+ * On success, it returns the file descriptor. On failure it returns -1.
  * If there is a failure, it prints the error to stderr.
  */
 int create_and_get_cgroup(const char *path)
@@ -166,13 +166,13 @@ int create_and_get_cgroup(const char *path)
 	format_cgroup_path(cgroup_path, path);
 	if (mkdir(cgroup_path, 0777) && errno != EEXIST) {
 		log_err("mkdiring cgroup %s .. %s", path, cgroup_path);
-		return 0;
+		return -1;
 	}
 
 	fd = open(cgroup_path, O_RDONLY);
 	if (fd < 0) {
 		log_err("Opening Cgroup");
-		return 0;
+		return -1;
 	}
 
 	return fd;