bblum

#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);