[urcu.git] / urcu / static / rculfstack.h

#ifndef _URCU_RCULFSTACK_STATIC_H
#define _URCU_RCULFSTACK_STATIC_H

/*
 * rculfstack-static.h
 *
 * Userspace RCU library - Lock-Free RCU Stack
 *
 * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See rculfstack.h for linking
 * dynamically with the userspace rcu library.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <urcu/uatomic.h>

#ifdef __cplusplus
extern "C" {
#endif

static inline
void _cds_lfs_node_init_rcu(struct cds_lfs_node_rcu *node)
{
}

static inline
void _cds_lfs_init_rcu(struct cds_lfs_stack_rcu *s)
{
	s->head = NULL;
}

static inline
void _cds_lfs_push_rcu(struct cds_lfs_stack_rcu *s, struct cds_lfs_node_rcu *node)
{
	struct cds_lfs_node_rcu *head = NULL;

	for (;;) {
		struct cds_lfs_node_rcu *old_head = head;

		node->next = head;
		/*
		 * uatomic_cmpxchg() implicit memory barrier orders earlier
		 * stores to node before publication.
		 */
		head = uatomic_cmpxchg(&s->head, old_head, node);
		if (old_head == head)
			break;
	}
}

/*
 * Acts as a RCU reader.
 *
 * The caller must wait for a grace period to pass before freeing the returned
 * node or modifying the cds_lfs_node_rcu structure.
 * Returns NULL if stack is empty.
 */
static inline
struct cds_lfs_node_rcu *
_cds_lfs_pop_rcu(struct cds_lfs_stack_rcu *s)
{
	for (;;) {
		struct cds_lfs_node_rcu *head;

		rcu_read_lock();
		head = rcu_dereference(s->head);
		if (head) {
			struct cds_lfs_node_rcu *next = rcu_dereference(head->next);

			if (uatomic_cmpxchg(&s->head, head, next) == head) {
				rcu_read_unlock();
				return head;
			} else {
				/* Concurrent modification. Retry. */
				rcu_read_unlock();
				continue;
			}
		} else {
			/* Empty stack */
			rcu_read_unlock();
			return NULL;
		}
	}
}

#ifdef __cplusplus
}
#endif

#endif /* _URCU_RCULFSTACK_STATIC_H */
Commit	Line	Data
b6a37eac MD	1	#ifndef _URCU_RCULFSTACK_STATIC_H
	2	#define _URCU_RCULFSTACK_STATIC_H
	3
	4	/*
	5	* rculfstack-static.h
	6	*
	7	* Userspace RCU library - Lock-Free RCU Stack
	8	*
	9	* Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	10	*
	11	* TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See rculfstack.h for linking
	12	* dynamically with the userspace rcu library.
	13	*
	14	* This library is free software; you can redistribute it and/or
	15	* modify it under the terms of the GNU Lesser General Public
	16	* License as published by the Free Software Foundation; either
	17	* version 2.1 of the License, or (at your option) any later version.
	18	*
	19	* This library is distributed in the hope that it will be useful,
	20	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	21	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	22	* Lesser General Public License for more details.
	23	*
	24	* You should have received a copy of the GNU Lesser General Public
	25	* License along with this library; if not, write to the Free Software
	26	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	27	*/
	28
a2e7bf9c	29	#include <urcu/uatomic.h>
b6a37eac MD	30
	31	#ifdef __cplusplus
	32	extern "C" {
	33	#endif
	34
bd0662db	35	static inline
16aa9ee8	36	void _cds_lfs_node_init_rcu(struct cds_lfs_node_rcu *node)
b6a37eac MD	37	{
	38	}
	39
bd0662db	40	static inline
16aa9ee8	41	void _cds_lfs_init_rcu(struct cds_lfs_stack_rcu *s)
b6a37eac MD	42	{
	43	s->head = NULL;
	44	}
	45
bd0662db	46	static inline
16aa9ee8	47	void _cds_lfs_push_rcu(struct cds_lfs_stack_rcu s, struct cds_lfs_node_rcu node)
b6a37eac	48	{
16aa9ee8	49	struct cds_lfs_node_rcu *head = NULL;
75202035	50
b6a37eac	51	for (;;) {
16aa9ee8	52	struct cds_lfs_node_rcu *old_head = head;
b6a37eac	53
b6a37eac MD	54	node->next = head;
	55	/*
	56	* uatomic_cmpxchg() implicit memory barrier orders earlier
	57	* stores to node before publication.
	58	*/
75202035 MD	59	head = uatomic_cmpxchg(&s->head, old_head, node);
	60	if (old_head == head)
	61	break;
b6a37eac MD	62	}
	63	}
	64
	65	/*
7618919a	66	* Acts as a RCU reader.
d9b52143	67	*
b6a37eac	68	* The caller must wait for a grace period to pass before freeing the returned
16aa9ee8	69	* node or modifying the cds_lfs_node_rcu structure.
b6a37eac MD	70	* Returns NULL if stack is empty.
b6a37eac MD	71	*/
bd0662db	72	static inline
16aa9ee8 DG	73	struct cds_lfs_node_rcu *
16aa9ee8 DG	74	_cds_lfs_pop_rcu(struct cds_lfs_stack_rcu *s)
b6a37eac MD	75	{
b6a37eac MD	76	for (;;) {
16aa9ee8	77	struct cds_lfs_node_rcu *head;
b6a37eac	78
7618919a	79	rcu_read_lock();
4fc06b7f MD	80	head = rcu_dereference(s->head);
4fc06b7f MD	81	if (head) {
16aa9ee8	82	struct cds_lfs_node_rcu *next = rcu_dereference(head->next);
b6a37eac	83
4fc06b7f	84	if (uatomic_cmpxchg(&s->head, head, next) == head) {
7618919a	85	rcu_read_unlock();
4fc06b7f MD	86	return head;
	87	} else {
	88	/* Concurrent modification. Retry. */
7618919a	89	rcu_read_unlock();
4fc06b7f MD	90	continue;
	91	}
	92	} else {
	93	/* Empty stack */
7618919a	94	rcu_read_unlock();
4fc06b7f MD	95	return NULL;
4fc06b7f MD	96	}
b6a37eac MD	97	}
	98	}
	99
	100	#ifdef __cplusplus
	101	}
	102	#endif
	103
	104	#endif /* _URCU_RCULFSTACK_STATIC_H */