1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
/*
* Copyright (C) 2001 Jason Evans <jasone@freebsd.org>. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice(s), this list of conditions and the following disclaimer as
* the first lines of this file unmodified other than the possible
* addition of one or more copyright notices.
* 2. Redistributions in binary form must reproduce the above copyright
* notice(s), this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* $FreeBSD$
*/
#ifndef _SYS_SX_H_
#define _SYS_SX_H_
#ifndef LOCORE
#include <sys/mutex.h>
#include <sys/condvar.h>
struct sx {
struct mtx sx_lock; /* General protection lock. */
const char *sx_descr; /* sx lock description. */
int sx_cnt; /* -1: xlock, > 0: slock count. */
struct cv sx_shrd_cv; /* slock waiters. */
int sx_shrd_wcnt; /* Number of slock waiters. */
struct cv sx_excl_cv; /* xlock waiters. */
int sx_excl_wcnt; /* Number of xlock waiters. */
struct proc *sx_xholder; /* Thread presently holding xlock. */
};
#ifdef _KERNEL
void sx_init(struct sx *sx, const char *description);
void sx_destroy(struct sx *sx);
void sx_slock(struct sx *sx);
void sx_xlock(struct sx *sx);
void sx_sunlock(struct sx *sx);
void sx_xunlock(struct sx *sx);
#ifdef INVARIANTS
/*
* SX_ASSERT_SLOCKED() can only detect that at least *some* thread owns an
* slock, but it cannot guarantee that *this* thread owns an slock.
*/
#define SX_ASSERT_SLOCKED(sx) do { \
mtx_lock(&(sx)->sx_lock); \
KASSERT(((sx)->sx_cnt > 0), ("%s: lacking slock %s\n", \
__FUNCTION__, (sx)->sx_descr)); \
mtx_unlock(&(sx)->sx_lock); \
} while (0)
/*
* SX_ASSERT_XLOCKED() detects and guarantees that *we* own the xlock.
*/
#define SX_ASSERT_XLOCKED(sx) do { \
mtx_lock(&(sx)->sx_lock); \
KASSERT(((sx)->sx_xholder == curproc), \
("%s: thread %p lacking xlock %s\n", __FUNCTION__, \
(sx)->sx_descr, curproc)); \
mtx_unlock(&(sx)->sx_lock); \
} while (0)
#else /* INVARIANTS */
#define SX_ASSERT_SLOCKED(sx)
#define SX_ASSERT_XLOCKER(sx)
#endif /* INVARIANTS */
#endif /* _KERNEL */
#endif /* !LOCORE */
#endif /* _SYS_SX_H_ */
|
