// SPDX-FileCopyrightText: 2002 Free Software Foundation, Inc.
// SPDX-FileCopyrightText: 2009 Pierre-Marc Fournier
// SPDX-FileCopyrightText: 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
//
// SPDX-License-Identifier: LGPL-2.1-or-later

/*
 * (originally part of the GNU C Library)
 * Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
 */

#ifndef _URCU_RCUHLIST_H
#define _URCU_RCUHLIST_H

#include <urcu/hlist.h>
#include <urcu/arch.h>
#include <urcu/uatomic.h>
#include <urcu-pointer.h>

/* Add new element at the head of the list. */
static inline
void cds_hlist_add_head_rcu(struct cds_hlist_node *newp,
		struct cds_hlist_head *head)
{
	newp->next = head->next;
	newp->prev = (struct cds_hlist_node *)head;
	if (head->next)
		head->next->prev = newp;
	rcu_assign_pointer(head->next, newp);
}

/* Remove element from list. */
static inline
void cds_hlist_del_rcu(struct cds_hlist_node *elem)
{
	if (elem->next)
		elem->next->prev = elem->prev;
	uatomic_store(&elem->prev->next, elem->next);
}

/*
 * Iterate through elements of the list.
 * This must be done while rcu_read_lock() is held.
 */
#define cds_hlist_for_each_rcu(pos, head) \
	for (pos = rcu_dereference((head)->next); (pos) != NULL; \
		pos = rcu_dereference((pos)->next))

/*
 * cds_hlist_for_each_entry_rcu takes 4 arguments, while the Linux
 * kernel API only takes 3.
 * We implement cds_hlist_for_each_entry_rcu_2() to follow the Linux
 * kernel APIs.
 */
#define cds_hlist_for_each_entry_rcu(entry, pos, head, member) \
	for (pos = rcu_dereference((head)->next), \
			entry = cds_hlist_entry(pos, __typeof__(*(entry)), member); \
		(pos) != NULL; \
		pos = rcu_dereference((pos)->next), \
			entry = cds_hlist_entry(pos, __typeof__(*(entry)), member))

#define cds_hlist_for_each_entry_rcu_2(entry, head, member) \
	for (entry = cds_hlist_entry_safe(rcu_dereference((head)->next), \
			__typeof__(*(entry)), member); \
		(entry) != NULL; \
		entry = cds_hlist_entry_safe(rcu_dereference((entry)->member.next), \
			__typeof__(*(entry)), member))

#endif	/* _URCU_RCUHLIST_H */