1 /*
2 * This file and its contents are supplied under the terms of the
3 * Common Development and Distribution License ("CDDL"), version 1.0.
4 * You may only use this file in accordance with the terms of version
5 * 1.0 of the CDDL.
6 *
7 * A full copy of the text of the CDDL should have accompanied this
8 * source. A copy of the CDDL is also available via the Internet at
9 * http://www.illumos.org/license/CDDL.
10 */
11
12 /*
13 * Copyright 2013 Nexenta Systems, Inc. All rights reserved.
14 */
15
16 /*
17 * rwlock(9f)
18 */
19
20 /* This is the API we're emulating */
21 #include <sys/rwlock.h>
22
23 #include <sys/errno.h>
24 #include <sys/debug.h>
25 #include <sys/param.h>
26 #include <sys/synch32.h>
27 #include <sys/thread.h>
28
29 /* avoiding synch.h */
30 int rwlock_init(lwp_rwlock_t *, int, void *);
31 int rwlock_destroy(lwp_rwlock_t *);
32 int rw_rdlock(lwp_rwlock_t *);
33 int rw_wrlock(lwp_rwlock_t *);
34 int rw_unlock(lwp_rwlock_t *);
35 int rw_tryrdlock(lwp_rwlock_t *);
36 int rw_trywrlock(lwp_rwlock_t *);
37 int _rw_read_held(void *);
38 int _rw_write_held(void *);
39
40 /*ARGSUSED*/
41 void
rw_init(krwlock_t * rwlp,char * name,krw_type_t type,void * arg)42 rw_init(krwlock_t *rwlp, char *name, krw_type_t type, void *arg)
43 {
44 (void) rwlock_init(&rwlp->rw_lock, USYNC_THREAD, NULL);
45 rwlp->rw_owner = _KTHREAD_INVALID;
46 }
47
48 void
rw_destroy(krwlock_t * rwlp)49 rw_destroy(krwlock_t *rwlp)
50 {
51 (void) rwlock_destroy(&rwlp->rw_lock);
52 rwlp->rw_owner = _KTHREAD_INVALID;
53 }
54
55 void
rw_enter(krwlock_t * rwlp,krw_t rw)56 rw_enter(krwlock_t *rwlp, krw_t rw)
57 {
58 int rc;
59
60 if (rw == RW_READER) {
61 rc = rw_rdlock(&rwlp->rw_lock);
62 } else {
63 rc = rw_wrlock(&rwlp->rw_lock);
64 rwlp->rw_owner = _curthread();
65 }
66 VERIFY(rc == 0);
67 }
68
69 void
rw_exit(krwlock_t * rwlp)70 rw_exit(krwlock_t *rwlp)
71 {
72 if (_rw_write_held(&rwlp->rw_lock)) {
73 ASSERT(rwlp->rw_owner == _curthread());
74 rwlp->rw_owner = _KTHREAD_INVALID;
75 }
76 (void) rw_unlock(&rwlp->rw_lock);
77 }
78
79 int
rw_tryenter(krwlock_t * rwlp,krw_t rw)80 rw_tryenter(krwlock_t *rwlp, krw_t rw)
81 {
82 int rv;
83
84 if (rw == RW_WRITER) {
85 rv = rw_trywrlock(&rwlp->rw_lock);
86 if (rv == 0)
87 rwlp->rw_owner = _curthread();
88 } else
89 rv = rw_tryrdlock(&rwlp->rw_lock);
90
91 return ((rv == 0) ? 1 : 0);
92 }
93
94 /*ARGSUSED*/
95 int
rw_tryupgrade(krwlock_t * rwlp)96 rw_tryupgrade(krwlock_t *rwlp)
97 {
98
99 return (0);
100 }
101
102 void
rw_downgrade(krwlock_t * rwlp)103 rw_downgrade(krwlock_t *rwlp)
104 {
105 ASSERT(rwlp->rw_owner == _curthread());
106 rwlp->rw_owner = _KTHREAD_INVALID;
107 VERIFY(rw_unlock(&rwlp->rw_lock) == 0);
108 VERIFY(rw_rdlock(&rwlp->rw_lock) == 0);
109 }
110
111 int
rw_read_held(krwlock_t * rwlp)112 rw_read_held(krwlock_t *rwlp)
113 {
114 return (_rw_read_held(rwlp));
115 }
116
117 int
rw_write_held(krwlock_t * rwlp)118 rw_write_held(krwlock_t *rwlp)
119 {
120 return (_rw_write_held(rwlp));
121 }
122
123 int
rw_lock_held(krwlock_t * rwlp)124 rw_lock_held(krwlock_t *rwlp)
125 {
126 return (rw_read_held(rwlp) || rw_write_held(rwlp));
127 }
128
129 /*
130 * Return the kthread_t * of the lock owner
131 */
132 void *
rw_owner(krwlock_t * rwlp)133 rw_owner(krwlock_t *rwlp)
134 {
135 return (rwlp->rw_owner);
136 }
137