// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2020 Facebook

#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>

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

struct sample {
        int pid;
        int seq;
        long value;
        char comm[16];
};

struct ringbuf_map {
        __uint(type, BPF_MAP_TYPE_RINGBUF);
        /* libbpf will adjust to valid page size */
        __uint(max_entries, 1000);
} ringbuf1 SEC(".maps"),
  ringbuf2 SEC(".maps");

struct {
        __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
        __uint(max_entries, 4);
        __type(key, int);
        __array(values, struct ringbuf_map);
} ringbuf_arr SEC(".maps") = {
        .values = {
                [0] = &ringbuf1,
                [2] = &ringbuf2,
        },
};

struct {
        __uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
        __uint(max_entries, 1);
        __type(key, int);
        __array(values, struct ringbuf_map);
} ringbuf_hash SEC(".maps") = {
        .values = {
                [0] = &ringbuf1,
        },
};

/* inputs */
int pid = 0;
int target_ring = 0;
long value = 0;

/* outputs */
long total = 0;
long dropped = 0;
long skipped = 0;

SEC("tp/syscalls/sys_enter_getpgid")
int test_ringbuf(void *ctx)
{
        int cur_pid = bpf_get_current_pid_tgid() >> 32;
        struct sample *sample;
        void *rb;

        if (cur_pid != pid)
                return 0;

        rb = bpf_map_lookup_elem(&ringbuf_arr, &target_ring);
        if (!rb) {
                skipped += 1;
                return 1;
        }

        sample = bpf_ringbuf_reserve(rb, sizeof(*sample), 0);
        if (!sample) {
                dropped += 1;
                return 1;
        }

        sample->pid = pid;
        bpf_get_current_comm(sample->comm, sizeof(sample->comm));
        sample->value = value;

        sample->seq = total;
        total += 1;

        bpf_ringbuf_submit(sample, 0);

        return 0;
}