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