selftests: cgroup_util: Add helpers for testing named v1 hierarchies

Non-functional change, the control variable will be wired in a separate
commit.

Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Author: Werkov

tools/testing/selftests/cgroup/lib/cgroup_util.c

@@ -19,6 +19,8 @@
 #include "cgroup_util.h"
 #include "../../clone3/clone3_selftests.h"
 
+bool cg_test_v1_named;
+
 /* Returns read len on success, or -errno on failure. */
 ssize_t read_text(const char *path, char *buf, size_t max_len)
 {
@@ -361,7 +363,7 @@ int cg_enter_current(const char *cgroup)
 
 int cg_enter_current_thread(const char *cgroup)
 {
-	return cg_write(cgroup, "cgroup.threads", "0");
+	return cg_write(cgroup, CG_THREADS_FILE, "0");
 }
 
 int cg_run(const char *cgroup,

tools/testing/selftests/cgroup/lib/include/cgroup_util.h

@@ -13,6 +13,10 @@
 
 #define TEST_UID	65534 /* usually nobody, any !root is fine */
 
+#define CG_THREADS_FILE (!cg_test_v1_named ? "cgroup.threads" : "tasks")
+#define CG_NAMED_NAME "selftest"
+#define CG_PATH_FORMAT (!cg_test_v1_named ? "0::%s" : (":name=" CG_NAMED_NAME ":%s"))
+
 /*
  * Checks if two given values differ by less than err% of their sum.
  */
@@ -65,3 +69,4 @@ extern int dirfd_open_opath(const char *dir);
 extern int cg_prepare_for_wait(const char *cgroup);
 extern int memcg_prepare_for_wait(const char *cgroup);
 extern int cg_wait_for(int fd);
+extern bool cg_test_v1_named;

tools/testing/selftests/cgroup/test_core.c

@@ -573,7 +573,7 @@ static int test_cgcore_proc_migration(const char *root)
 	}
 
 	cg_enter_current(dst);
-	if (cg_read_lc(dst, "cgroup.threads") != n_threads + 1)
+	if (cg_read_lc(dst, CG_THREADS_FILE) != n_threads + 1)
 		goto cleanup;
 
 	ret = KSFT_PASS;
@@ -605,7 +605,7 @@ static void *migrating_thread_fn(void *arg)
 	char lines[3][PATH_MAX];
 
 	for (g = 1; g < 3; ++g)
-		snprintf(lines[g], sizeof(lines[g]), "0::%s", grps[g] + strlen(grps[0]));
+		snprintf(lines[g], sizeof(lines[g]), CG_PATH_FORMAT, grps[g] + strlen(grps[0]));
 
 	for (i = 0; i < n_iterations; ++i) {
 		cg_enter_current_thread(grps[(i % 2) + 1]);
@@ -659,7 +659,7 @@ static int test_cgcore_thread_migration(const char *root)
 	if (retval)
 		goto cleanup;
 
-	snprintf(line, sizeof(line), "0::%s", grps[1] + strlen(grps[0]));
+	snprintf(line, sizeof(line), CG_PATH_FORMAT, grps[1] + strlen(grps[0]));
 	if (proc_read_strstr(0, 1, "cgroup", line))
 		goto cleanup;