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 2017 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/thread.h>
27
28 /* avoiding synch.h */
29 int rwlock_init(lwp_rwlock_t *, int, void *);
30 int rwlock_destroy(lwp_rwlock_t *);
31 int rw_rdlock(lwp_rwlock_t *);
32 int rw_wrlock(lwp_rwlock_t *);
33 int rw_unlock(lwp_rwlock_t *);
34 int rw_tryrdlock(lwp_rwlock_t *);
35 int rw_trywrlock(lwp_rwlock_t *);
36 int _rw_read_held(void *);
37 int _rw_write_held(void *);
38
39 /*ARGSUSED*/
40 void
rw_init(krwlock_t * rwlp,char * name,krw_type_t type,void * arg)41 rw_init(krwlock_t *rwlp, char *name, krw_type_t type, void *arg)
42 {
43 (void) rwlock_init(&rwlp->rw_lock, USYNC_THREAD, NULL);
44 rwlp->rw_owner = _KTHREAD_INVALID;
45 }
46
47 void
rw_destroy(krwlock_t * rwlp)48 rw_destroy(krwlock_t *rwlp)
49 {
50 (void) rwlock_destroy(&rwlp->rw_lock);
51 rwlp->rw_owner = _KTHREAD_INVALID;
52 }
53
54 void
rw_enter(krwlock_t * rwlp,krw_t rw)55 rw_enter(krwlock_t *rwlp, krw_t rw)
56 {
57 int rc;
58
59 if (rw == RW_READER) {
60 rc = rw_rdlock(&rwlp->rw_lock);
61 } else {
62 rc = rw_wrlock(&rwlp->rw_lock);
63 rwlp->rw_owner = _curthread();
64 }
65 VERIFY(rc == 0);
66 }
67
68 void
rw_exit(krwlock_t * rwlp)69 rw_exit(krwlock_t *rwlp)
70 {
71 if (_rw_write_held(&rwlp->rw_lock)) {
72 ASSERT(rwlp->rw_owner == _curthread());
73 rwlp->rw_owner = _KTHREAD_INVALID;
74 } else {
75 ASSERT(_rw_read_held(&rwlp->rw_lock));
76 }
77 (void) rw_unlock(&rwlp->rw_lock);
78 }
79
80 int
rw_tryenter(krwlock_t * rwlp,krw_t rw)81 rw_tryenter(krwlock_t *rwlp, krw_t rw)
82 {
83 int rv;
84
85 if (rw == RW_WRITER) {
86 rv = rw_trywrlock(&rwlp->rw_lock);
87 if (rv == 0)
88 rwlp->rw_owner = _curthread();
89 } else
90 rv = rw_tryrdlock(&rwlp->rw_lock);
91
92 return ((rv == 0) ? 1 : 0);
93 }
94
95 /*ARGSUSED*/
96 int
rw_tryupgrade(krwlock_t * rwlp)97 rw_tryupgrade(krwlock_t *rwlp)
98 {
99
100 return (0);
101 }
102
103 void
rw_downgrade(krwlock_t * rwlp)104 rw_downgrade(krwlock_t *rwlp)
105 {
106 ASSERT(rwlp->rw_owner == _curthread());
107 rwlp->rw_owner = _KTHREAD_INVALID;
108 VERIFY(rw_unlock(&rwlp->rw_lock) == 0);
109 VERIFY(rw_rdlock(&rwlp->rw_lock) == 0);
110 }
111
112 int
rw_read_held(krwlock_t * rwlp)113 rw_read_held(krwlock_t *rwlp)
114 {
115 return (_rw_read_held(rwlp));
116 }
117
118 int
rw_write_held(krwlock_t * rwlp)119 rw_write_held(krwlock_t *rwlp)
120 {
121 return (_rw_write_held(rwlp));
122 }
123
124 int
rw_lock_held(krwlock_t * rwlp)125 rw_lock_held(krwlock_t *rwlp)
126 {
127 return (rw_read_held(rwlp) || rw_write_held(rwlp));
128 }
129
130 /*
131 * Return the kthread_t * of the lock owner
132 */
133 void *
rw_owner(krwlock_t * rwlp)134 rw_owner(krwlock_t *rwlp)
135 {
136 return (rwlp->rw_owner);
137 }
138