/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_RCULIST_BL_H
#define _LINUX_RCULIST_BL_H

/*
 * RCU-protected bl list version. See include/linux/list_bl.h.
 */
#include <linux/list_bl.h>
#include <linux/rcupdate.h>

static inline void hlist_bl_set_first_rcu(struct hlist_bl_head *h,
                                        struct hlist_bl_node *n)
{
        LIST_BL_BUG_ON((unsigned long)n & LIST_BL_LOCKMASK);
        LIST_BL_BUG_ON(((unsigned long)h->first & LIST_BL_LOCKMASK) !=
                                                        LIST_BL_LOCKMASK);
        rcu_assign_pointer(h->first,
                (struct hlist_bl_node *)((unsigned long)n | LIST_BL_LOCKMASK));
}

static inline struct hlist_bl_node *hlist_bl_first_rcu(struct hlist_bl_head *h)
{
        return (struct hlist_bl_node *)
                ((unsigned long)rcu_dereference_check(h->first, hlist_bl_is_locked(h)) & ~LIST_BL_LOCKMASK);
}

/**
 * hlist_bl_del_rcu - deletes entry from hash list without re-initialization
 * @n: the element to delete from the hash list.
 *
 * Note: hlist_bl_unhashed() on entry does not return true after this,
 * the entry is in an undefined state. It is useful for RCU based
 * lockfree traversal.
 *
 * In particular, it means that we can not poison the forward
 * pointers that may still be used for walking the hash list.
 *
 * The caller must take whatever precautions are necessary
 * (such as holding appropriate locks) to avoid racing
 * with another list-mutation primitive, such as hlist_bl_add_head_rcu()
 * or hlist_bl_del_rcu(), running on this same list.
 * However, it is perfectly legal to run concurrently with
 * the _rcu list-traversal primitives, such as
 * hlist_bl_for_each_entry().
 */
static inline void hlist_bl_del_rcu(struct hlist_bl_node *n)
{
        __hlist_bl_del(n);
        n->pprev = LIST_POISON2;
}

/**
 * hlist_bl_add_head_rcu
 * @n: the element to add to the hash list.
 * @h: the list to add to.
 *
 * Description:
 * Adds the specified element to the specified hlist_bl,
 * while permitting racing traversals.
 *
 * The caller must take whatever precautions are necessary
 * (such as holding appropriate locks) to avoid racing
 * with another list-mutation primitive, such as hlist_bl_add_head_rcu()
 * or hlist_bl_del_rcu(), running on this same list.
 * However, it is perfectly legal to run concurrently with
 * the _rcu list-traversal primitives, such as
 * hlist_bl_for_each_entry_rcu(), used to prevent memory-consistency
 * problems on Alpha CPUs.  Regardless of the type of CPU, the
 * list-traversal primitive must be guarded by rcu_read_lock().
 */
static inline void hlist_bl_add_head_rcu(struct hlist_bl_node *n,
                                        struct hlist_bl_head *h)
{
        struct hlist_bl_node *first;

        /* don't need hlist_bl_first_rcu because we're under lock */
        first = hlist_bl_first(h);

        n->next = first;
        if (first)
                first->pprev = &n->next;
        n->pprev = &h->first;

        /* need _rcu because we can have concurrent lock free readers */
        hlist_bl_set_first_rcu(h, n);
}
/**
 * hlist_bl_for_each_entry_rcu - iterate over rcu list of given type
 * @tpos:       the type * to use as a loop cursor.
 * @pos:        the &struct hlist_bl_node to use as a loop cursor.
 * @head:       the head for your list.
 * @member:     the name of the hlist_bl_node within the struct.
 *
 */
#define hlist_bl_for_each_entry_rcu(tpos, pos, head, member)            \
        for (pos = hlist_bl_first_rcu(head);                            \
                pos &&                                                  \
                ({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1; }); \
                pos = rcu_dereference_raw(pos->next))

#endif