// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */

#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
#include "bpf_experimental.h"

struct node_data {
        struct bpf_list_node l;
        int key;
};

#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
private(A) struct bpf_spin_lock glock;
private(A) struct bpf_list_head ghead __contains(node_data, l);

#define list_entry(ptr, type, member) container_of(ptr, type, member)
#define NR_NODES 16

int zero = 0;

SEC("syscall")
__retval(0)
long list_peek(void *ctx)
{
        struct bpf_list_node *l_n;
        struct node_data *n;
        int i, err = 0;

        bpf_spin_lock(&glock);
        l_n = bpf_list_front(&ghead);
        bpf_spin_unlock(&glock);
        if (l_n)
                return __LINE__;

        bpf_spin_lock(&glock);
        l_n = bpf_list_back(&ghead);
        bpf_spin_unlock(&glock);
        if (l_n)
                return __LINE__;

        for (i = zero; i < NR_NODES && can_loop; i++) {
                n = bpf_obj_new(typeof(*n));
                if (!n)
                        return __LINE__;
                n->key = i;
                bpf_spin_lock(&glock);
                bpf_list_push_back(&ghead, &n->l);
                bpf_spin_unlock(&glock);
        }

        bpf_spin_lock(&glock);

        l_n = bpf_list_front(&ghead);
        if (!l_n) {
                err = __LINE__;
                goto done;
        }

        n = list_entry(l_n, struct node_data, l);
        if (n->key != 0) {
                err = __LINE__;
                goto done;
        }

        l_n = bpf_list_back(&ghead);
        if (!l_n) {
                err = __LINE__;
                goto done;
        }

        n = list_entry(l_n, struct node_data, l);
        if (n->key != NR_NODES - 1) {
                err = __LINE__;
                goto done;
        }

done:
        bpf_spin_unlock(&glock);
        return err;
}

#define TEST_FB(op, dolock)                                     \
SEC("syscall")                                                  \
__failure __msg(MSG)                                            \
long test_##op##_spinlock_##dolock(void *ctx)                   \
{                                                               \
        struct bpf_list_node *l_n;                              \
        __u64 jiffies = 0;                                      \
                                                                \
        if (dolock)                                             \
                bpf_spin_lock(&glock);                          \
        l_n = bpf_list_##op(&ghead);                            \
        if (l_n)                                                \
                jiffies = bpf_jiffies64();                      \
        if (dolock)                                             \
                bpf_spin_unlock(&glock);                        \
                                                                \
        return !!jiffies;                                       \
}

#define MSG "call bpf_list_{{(front|back).+}}; R0{{(_w)?}}=ptr_or_null_node_data(id={{[0-9]+}},non_own_ref"
TEST_FB(front, true)
TEST_FB(back, true)
#undef MSG

#define MSG "bpf_spin_lock at off=0 must be held for bpf_list_head"
TEST_FB(front, false)
TEST_FB(back, false)
#undef MSG

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