// SPDX-License-Identifier: GPL-2.0
/*
 * Common Code for DAMON Sysfs Interface
 *
 * Author: SeongJae Park <sj@kernel.org>
 */

#include <linux/slab.h>

#include "sysfs-common.h"

DEFINE_MUTEX(damon_sysfs_lock);

/*
 * unsigned long range directory
 */

struct damon_sysfs_ul_range *damon_sysfs_ul_range_alloc(
		unsigned long min,
		unsigned long max)
{
	struct damon_sysfs_ul_range *range = kmalloc_obj(*range);

	if (!range)
		return NULL;
	range->kobj = (struct kobject){};
	range->min = min;
	range->max = max;

	return range;
}

static ssize_t min_show(struct kobject *kobj, struct kobj_attribute *attr,
		char *buf)
{
	struct damon_sysfs_ul_range *range = container_of(kobj,
			struct damon_sysfs_ul_range, kobj);

	return sysfs_emit(buf, "%lu\n", range->min);
}

static ssize_t min_store(struct kobject *kobj, struct kobj_attribute *attr,
		const char *buf, size_t count)
{
	struct damon_sysfs_ul_range *range = container_of(kobj,
			struct damon_sysfs_ul_range, kobj);
	unsigned long min;
	int err;

	err = kstrtoul(buf, 0, &min);
	if (err)
		return err;

	range->min = min;
	return count;
}

static ssize_t max_show(struct kobject *kobj, struct kobj_attribute *attr,
		char *buf)
{
	struct damon_sysfs_ul_range *range = container_of(kobj,
			struct damon_sysfs_ul_range, kobj);

	return sysfs_emit(buf, "%lu\n", range->max);
}

static ssize_t max_store(struct kobject *kobj, struct kobj_attribute *attr,
		const char *buf, size_t count)
{
	struct damon_sysfs_ul_range *range = container_of(kobj,
			struct damon_sysfs_ul_range, kobj);
	unsigned long max;
	int err;

	err = kstrtoul(buf, 0, &max);
	if (err)
		return err;

	range->max = max;
	return count;
}

void damon_sysfs_ul_range_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damon_sysfs_ul_range, kobj));
}

static struct kobj_attribute damon_sysfs_ul_range_min_attr =
		__ATTR_RW_MODE(min, 0600);

static struct kobj_attribute damon_sysfs_ul_range_max_attr =
		__ATTR_RW_MODE(max, 0600);

static struct attribute *damon_sysfs_ul_range_attrs[] = {
	&damon_sysfs_ul_range_min_attr.attr,
	&damon_sysfs_ul_range_max_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_ul_range);

const struct kobj_type damon_sysfs_ul_range_ktype = {
	.release = damon_sysfs_ul_range_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_ul_range_groups,
};


static bool damon_sysfs_memcg_path_eq(struct mem_cgroup *memcg,
		char *memcg_path_buf, char *path)
{
#ifdef CONFIG_MEMCG
	cgroup_path(memcg->css.cgroup, memcg_path_buf, PATH_MAX);
	if (sysfs_streq(memcg_path_buf, path))
		return true;
#endif /* CONFIG_MEMCG */
	return false;
}

int damon_sysfs_memcg_path_to_id(char *memcg_path, u64 *id)
{
	struct mem_cgroup *memcg;
	char *path;
	bool found = false;

	if (!memcg_path)
		return -EINVAL;

	path = kmalloc_array(PATH_MAX, sizeof(*path), GFP_KERNEL);
	if (!path)
		return -ENOMEM;

	for (memcg = mem_cgroup_iter(NULL, NULL, NULL); memcg;
			memcg = mem_cgroup_iter(NULL, memcg, NULL)) {
		/* skip offlined memcg */
		if (!mem_cgroup_online(memcg))
			continue;
		if (damon_sysfs_memcg_path_eq(memcg, path, memcg_path)) {
			*id = mem_cgroup_id(memcg);
			found = true;
			mem_cgroup_iter_break(NULL, memcg);
			break;
		}
	}

	kfree(path);
	return found ? 0 : -EINVAL;
}