kselftests: cgroup: add freezer mkdir test

Add a new cgroup freezer selftest, which checks that if a cgroup is
frozen, their new child cgroups will properly inherit the frozen
state.

It creates a parent cgroup, freezes it, creates a child cgroup
and populates it with a dummy process. Then it checks that both
parent and child cgroup are frozen.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/tools/testing/selftests/cgroup/test_freezer.c b/tools/testing/selftests/cgroup/test_freezer.c
index 8219a30853d283fa65baa1be4f16036d7cf542a8..0fc1b6d4b0f9c4db9084158fd22b755e7b53482f 100644 (file)
--- a/tools/testing/selftests/cgroup/test_freezer.c
+++ b/tools/testing/selftests/cgroup/test_freezer.c
@@ -447,6 +447,59 @@ cleanup:
        return ret;
 }
 
+/*
+ * The test creates a cgroups and freezes it. Then it creates a child cgroup
+ * and populates it with a task. After that it checks that the child cgroup
+ * is frozen and the parent cgroup remains frozen too.
+ */
+static int test_cgfreezer_mkdir(const char *root)
+{
+       int ret = KSFT_FAIL;
+       char *parent, *child = NULL;
+       int pid;
+
+       parent = cg_name(root, "cg_test_mkdir_A");
+       if (!parent)
+               goto cleanup;
+
+       child = cg_name(parent, "cg_test_mkdir_B");
+       if (!child)
+               goto cleanup;
+
+       if (cg_create(parent))
+               goto cleanup;
+
+       if (cg_freeze_wait(parent, true))
+               goto cleanup;
+
+       if (cg_create(child))
+               goto cleanup;
+
+       pid = cg_run_nowait(child, child_fn, NULL);
+       if (pid < 0)
+               goto cleanup;
+
+       if (cg_wait_for_proc_count(child, 1))
+               goto cleanup;
+
+       if (cg_check_frozen(child, true))
+               goto cleanup;
+
+       if (cg_check_frozen(parent, true))
+               goto cleanup;
+
+       ret = KSFT_PASS;
+
+cleanup:
+       if (child)
+               cg_destroy(child);
+       free(child);
+       if (parent)
+               cg_destroy(parent);
+       free(parent);
+       return ret;
+}
+
 /*
  * The test creates two nested cgroups, freezes the parent
  * and removes the child. Then it checks that the parent cgroup
@@ -815,6 +868,7 @@ struct cgfreezer_test {
        T(test_cgfreezer_simple),
        T(test_cgfreezer_tree),
        T(test_cgfreezer_forkbomb),
+       T(test_cgfreezer_mkdir),
        T(test_cgfreezer_rmdir),
        T(test_cgfreezer_migrate),
        T(test_cgfreezer_ptrace),