#include <linux/module.h>
#include <linux/cgroup.h>
#include <linux/fs.h>
#include <linux/slab.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("bblom");

u64 test1 = 0;

struct test1_cgroup {
	struct cgroup_subsys_state css;
};

static struct cgroup_subsys_state *test1_create(struct cgroup_subsys *ss,
						struct cgroup *cgroup)
{
	struct test1_cgroup *foo = kzalloc(sizeof(*foo), GFP_KERNEL);
	if (!foo)
		return ERR_PTR(-ENOMEM);
	return &foo->css;
}

static int test1_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup,
			    struct task_struct *task, bool threadgroup)
{
	if (test1 == 42)
		return 0;
	return -EPERM;
}

static int test1_write(struct cgroup *cgrp, struct cftype *cft, u64 val)
{
	test1 = val;
	return 0;
}

static u64 test1_read(struct cgroup *cgrp, struct cftype *cft)
{
	return test1;
}

static struct cftype test1_file = {
	.name = "hax",
	.write_u64 = test1_write,
	.read_u64 = test1_read,
};

static int test1_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
{
	return cgroup_add_file(cgroup, ss, &test1_file);
}

struct cgroup_subsys test1_subsys = {
	.name = "test1",
	.can_attach = test1_can_attach,
	.create = test1_create,
	.populate = test1_populate,
	.module = THIS_MODULE,
};

static int test1_load(void)
{
	return cgroup_load_subsys(&test1_subsys);
}
module_init(test1_load);