atomic.h revision 297658 
1/*-
2 * Copyright (c) 2010 Isilon Systems, Inc.
3 * Copyright (c) 2010 iX Systems, Inc.
4 * Copyright (c) 2010 Panasas, Inc.
5 * Copyright (c) 2013-2016 Mellanox Technologies, Ltd.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice unmodified, this list of conditions, and the following
13 *    disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30#ifndef	_ASM_ATOMIC_H_
31#define	_ASM_ATOMIC_H_
32
33#include <sys/cdefs.h>
34#include <sys/types.h>
35#include <machine/atomic.h>
36
37typedef struct {
38	volatile int counter;
39} atomic_t;
40
41/*------------------------------------------------------------------------*
42 *	32-bit atomic operations
43 *------------------------------------------------------------------------*/
44
45#define	atomic_add(i, v)		atomic_add_return((i), (v))
46#define	atomic_sub(i, v)		atomic_sub_return((i), (v))
47#define	atomic_inc_return(v)		atomic_add_return(1, (v))
48#define	atomic_add_negative(i, v)	(atomic_add_return((i), (v)) < 0)
49#define	atomic_sub_and_test(i, v)	(atomic_sub_return((i), (v)) == 0)
50#define	atomic_dec_and_test(v)		(atomic_sub_return(1, (v)) == 0)
51#define	atomic_inc_and_test(v)		(atomic_add_return(1, (v)) == 0)
52#define	atomic_dec_return(v)		atomic_sub_return(1, (v))
53#define	atomic_inc_not_zero(v)		atomic_add_unless((v), 1, 0)
54
55static inline int
56atomic_add_return(int i, atomic_t *v)
57{
58	return i + atomic_fetchadd_int(&v->counter, i);
59}
60
61static inline int
62atomic_sub_return(int i, atomic_t *v)
63{
64	return atomic_fetchadd_int(&v->counter, -i) - i;
65}
66
67static inline void
68atomic_set(atomic_t *v, int i)
69{
70	atomic_store_rel_int(&v->counter, i);
71}
72
73static inline int
74atomic_read(atomic_t *v)
75{
76	return atomic_load_acq_int(&v->counter);
77}
78
79static inline int
80atomic_inc(atomic_t *v)
81{
82	return atomic_fetchadd_int(&v->counter, 1) + 1;
83}
84
85static inline int
86atomic_dec(atomic_t *v)
87{
88	return atomic_fetchadd_int(&v->counter, -1) - 1;
89}
90
91static inline int
92atomic_add_unless(atomic_t *v, int a, int u)
93{
94	int c;
95
96	for (;;) {
97		c = atomic_read(v);
98		if (unlikely(c == u))
99			break;
100		if (likely(atomic_cmpset_int(&v->counter, c, c + a)))
101			break;
102	}
103	return (c != u);
104}
105
106#endif					/* _ASM_ATOMIC_H_ */
107