/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
#pragma once
#include "bpf_arena_common.h"

struct arena_list_node;

typedef struct arena_list_node __arena arena_list_node_t;

struct arena_list_node {
        arena_list_node_t *next;
        arena_list_node_t * __arena *pprev;
};

struct arena_list_head {
        struct arena_list_node __arena *first;
};
typedef struct arena_list_head __arena arena_list_head_t;

#define list_entry(ptr, type, member) arena_container_of(ptr, type, member)

#define list_entry_safe(ptr, type, member) \
        ({ typeof(*ptr) * ___ptr = (ptr); \
         ___ptr ? ({ cast_kern(___ptr); list_entry(___ptr, type, member); }) : NULL; \
         })

#ifndef __BPF__
static inline void *bpf_iter_num_new(struct bpf_iter_num *it, int i, int j) { return NULL; }
static inline void bpf_iter_num_destroy(struct bpf_iter_num *it) {}
static inline bool bpf_iter_num_next(struct bpf_iter_num *it) { return true; }
#define cond_break ({})
#define can_loop true
#endif

/* Safely walk link list elements. Deletion of elements is allowed. */
#define list_for_each_entry(pos, head, member)                                  \
        for (void * ___tmp = (pos = list_entry_safe((head)->first,              \
                                                    typeof(*(pos)), member),    \
                              (void *)0);                                       \
             pos && ({ ___tmp = (void *)pos->member.next; 1; }) && can_loop;    \
             pos = list_entry_safe((void __arena *)___tmp, typeof(*(pos)), member))

static inline void list_add_head(arena_list_node_t *n, arena_list_head_t *h)
{
        arena_list_node_t *first = h->first, * __arena *tmp;

        cast_user(first);
        cast_kern(n);
        WRITE_ONCE(n->next, first);
        cast_kern(first);
        if (first) {
                tmp = &n->next;
                cast_user(tmp);
                WRITE_ONCE(first->pprev, tmp);
        }
        cast_user(n);
        WRITE_ONCE(h->first, n);

        tmp = &h->first;
        cast_user(tmp);
        cast_kern(n);
        WRITE_ONCE(n->pprev, tmp);
}

static inline void __list_del(arena_list_node_t *n)
{
        arena_list_node_t *next = n->next;
        arena_list_node_t * __arena *pprev = n->pprev;

        cast_user(next);
        cast_kern(pprev);
        WRITE_ONCE(*pprev, next);
        if (next) {
                cast_user(pprev);
                cast_kern(next);
                WRITE_ONCE(next->pprev, pprev);
        }
}

#define POISON_POINTER_DELTA 0

#define LIST_POISON1  ((void __arena *) 0x100 + POISON_POINTER_DELTA)
#define LIST_POISON2  ((void __arena *) 0x122 + POISON_POINTER_DELTA)

static inline void list_del(arena_list_node_t *n)
{
        __list_del(n);
        n->next = LIST_POISON1;
        n->pprev = LIST_POISON2;
}