/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */

#ifndef _CGRP_KFUNC_COMMON_H
#define _CGRP_KFUNC_COMMON_H

#include <errno.h>
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>

struct __cgrps_kfunc_map_value {
        struct cgroup __kptr * cgrp;
};

struct {
        __uint(type, BPF_MAP_TYPE_HASH);
        __type(key, int);
        __type(value, struct __cgrps_kfunc_map_value);
        __uint(max_entries, 1);
} __cgrps_kfunc_map SEC(".maps");

struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
void bpf_cgroup_release(struct cgroup *p) __ksym;
struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym;
struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
void bpf_rcu_read_lock(void) __ksym;
void bpf_rcu_read_unlock(void) __ksym;

static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp)
{
        s32 id;
        long status;

        status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
        if (status)
                return NULL;

        return bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
}

static inline int cgrps_kfunc_map_insert(struct cgroup *cgrp)
{
        struct __cgrps_kfunc_map_value local, *v;
        long status;
        struct cgroup *acquired, *old;
        s32 id;

        status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
        if (status)
                return status;

        local.cgrp = NULL;
        status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);
        if (status)
                return status;

        v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
        if (!v) {
                bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
                return -ENOENT;
        }

        acquired = bpf_cgroup_acquire(cgrp);
        if (!acquired) {
                bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
                return -ENOENT;
        }

        old = bpf_kptr_xchg(&v->cgrp, acquired);
        if (old) {
                bpf_cgroup_release(old);
                return -EEXIST;
        }

        return 0;
}

#endif /* _CGRP_KFUNC_COMMON_H */