atomic.h revision 271127 
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, 2014 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 u_int counter;
39} atomic_t;
40
41#define	atomic_add(i, v)		atomic_add_return((i), (v))
42#define	atomic_sub(i, v)		atomic_sub_return((i), (v))
43#define	atomic_inc_return(v)		atomic_add_return(1, (v))
44#define	atomic_add_negative(i, v)	(atomic_add_return((i), (v)) < 0)
45#define	atomic_sub_and_test(i, v)	(atomic_sub_return((i), (v)) == 0)
46#define	atomic_dec_and_test(v)		(atomic_sub_return(1, (v)) == 0)
47#define	atomic_inc_and_test(v)		(atomic_add_return(1, (v)) == 0)
48#define atomic_dec_return(v)             atomic_sub_return(1, (v))
49
50static inline int
51atomic_add_return(int i, atomic_t *v)
52{
53	return i + atomic_fetchadd_int(&v->counter, i);
54}
55
56static inline int
57atomic_sub_return(int i, atomic_t *v)
58{
59	return atomic_fetchadd_int(&v->counter, -i) - i;
60}
61
62static inline void
63atomic_set(atomic_t *v, int i)
64{
65	atomic_store_rel_int(&v->counter, i);
66}
67
68static inline int
69atomic_read(atomic_t *v)
70{
71	return atomic_load_acq_int(&v->counter);
72}
73
74static inline int
75atomic_inc(atomic_t *v)
76{
77	return atomic_fetchadd_int(&v->counter, 1) + 1;
78}
79
80static inline int
81atomic_dec(atomic_t *v)
82{
83	return atomic_fetchadd_int(&v->counter, -1) - 1;
84}
85
86static inline int atomic_add_unless(atomic_t *v, int a, int u)
87{
88        int c, old;
89        c = atomic_read(v);
90        for (;;) {
91                if (unlikely(c == (u)))
92                        break;
93                old = atomic_cmpset_int(&v->counter, c, c + (a));
94                if (likely(old == c))
95                        break;
96                c = old;
97        }
98        return c != (u);
99}
100
101#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
102
103
104
105
106#endif	/* _ASM_ATOMIC_H_ */
107