[PATCH v4 bpf-next 2/3] selftests/bpf: add per worker cgroup suffix

[Yucong Sun <fallentree@fb.com>]

From: Yucong Sun <sunyucong@gmail.com>

This patch allows each worker to use a unique cgroup base directory, thus
allowing tests that uses cgroups to run concurrently.

Signed-off-by: Yucong Sun <sunyucong@gmail.com>
---
 tools/testing/selftests/bpf/cgroup_helpers.c | 5 +++--
 tools/testing/selftests/bpf/cgroup_helpers.h | 1 +
 tools/testing/selftests/bpf/test_progs.c     | 5 +++++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c
index 033051717ba5..a0429f0d6db2 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.c
+++ b/tools/testing/selftests/bpf/cgroup_helpers.c
@@ -29,9 +29,10 @@
 #define WALK_FD_LIMIT			16
 #define CGROUP_MOUNT_PATH		"/mnt"
 #define CGROUP_WORK_DIR			"/cgroup-test-work-dir"
+const char *CGROUP_WORK_DIR_SUFFIX = "";
 #define format_cgroup_path(buf, path) \
-	snprintf(buf, sizeof(buf), "%s%s%s", CGROUP_MOUNT_PATH, \
-		 CGROUP_WORK_DIR, path)
+	snprintf(buf, sizeof(buf), "%s%s%s%s", CGROUP_MOUNT_PATH, \
+	CGROUP_WORK_DIR, CGROUP_WORK_DIR_SUFFIX, path)
 
 /**
  * enable_all_controllers() - Enable all available cgroup v2 controllers
diff --git a/tools/testing/selftests/bpf/cgroup_helpers.h b/tools/testing/selftests/bpf/cgroup_helpers.h
index 5fe3d88e4f0d..5657aba02161 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.h
+++ b/tools/testing/selftests/bpf/cgroup_helpers.h
@@ -16,4 +16,5 @@ int setup_cgroup_environment(void);
 void cleanup_cgroup_environment(void);
 unsigned long long get_cgroup_id(const char *path);
 
+extern const char *CGROUP_WORK_DIR_SUFFIX;
 #endif
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index c542e2d2f893..f0eeb17c348d 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -1076,6 +1076,11 @@ int server_main(void)
 
 int worker_main(int sock)
 {
+	static char suffix[16];
+
+	sprintf(suffix, "%d", env.worker_index);
+	CGROUP_WORK_DIR_SUFFIX = suffix;
+
 	save_netns();
 
 	while (true) {
-- 
2.30.2