// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
#include <vmlinux.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_helpers.h>

#include "bpf_misc.h"
#include "bpf_experimental.h"

struct node_data {
        __u64 data;
        struct bpf_list_node node;
};

struct map_value {
        struct bpf_list_head head __contains(node_data, node);
        struct bpf_spin_lock lock;
};

struct inner_array_type {
        __uint(type, BPF_MAP_TYPE_ARRAY);
        __type(key, int);
        __type(value, struct map_value);
        __uint(max_entries, 1);
} inner_array SEC(".maps");

struct {
        __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
        __uint(key_size, 4);
        __uint(value_size, 4);
        __uint(max_entries, 1);
        __array(values, struct inner_array_type);
} outer_array SEC(".maps") = {
        .values = {
                [0] = &inner_array,
        },
};

char _license[] SEC("license") = "GPL";

int pid = 0;
bool done = false;

SEC("fentry/" SYS_PREFIX "sys_nanosleep")
int add_to_list_in_inner_array(void *ctx)
{
        struct map_value *value;
        struct node_data *new;
        struct bpf_map *map;
        int zero = 0;

        if (done || (u32)bpf_get_current_pid_tgid() != pid)
                return 0;

        map = bpf_map_lookup_elem(&outer_array, &zero);
        if (!map)
                return 0;

        value = bpf_map_lookup_elem(map, &zero);
        if (!value)
                return 0;

        new = bpf_obj_new(typeof(*new));
        if (!new)
                return 0;

        bpf_spin_lock(&value->lock);
        bpf_list_push_back(&value->head, &new->node);
        bpf_spin_unlock(&value->lock);
        done = true;

        return 0;
}