2 * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, 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 AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 #include <sys/limits.h>
39 #define UMTX_UNOWNED 0x0
40 #define UMTX_CONTESTED LONG_MIN
43 void *u_owner; /* Owner of the mutex. */
46 /* op code for _umtx_op */
47 #define UMTX_OP_LOCK 0
48 #define UMTX_OP_UNLOCK 1
49 #define UMTX_OP_UNLOCK_AND_WAIT 2
50 #define UMTX_OP_WAKE 3
55 * System calls for acquiring and releasing contested mutexes.
57 /* deprecated becaues it can only use thread id */
58 int _umtx_lock(struct umtx *mtx);
59 /* deprecated becaues it can only use thread id */
60 int _umtx_unlock(struct umtx *mtx);
61 int _umtx_op(struct umtx *umtx, int op, long id, void *uaddr,
62 struct timespec *abstime);
65 * Standard api. Try uncontested acquire/release and asks the
66 * kernel to resolve failures.
69 umtx_init(struct umtx *umtx)
71 umtx->u_owner = UMTX_UNOWNED;
75 umtx_owner(struct umtx *umtx)
77 return ((long)umtx->u_owner & ~LONG_MIN);
81 umtx_lock(struct umtx *umtx, long id)
83 if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
85 if (_umtx_op(umtx, UMTX_OP_LOCK, id, 0, 0) == -1)
91 umtx_trylock(struct umtx *umtx, long id)
93 if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
100 umtx_timedlock(struct umtx *umtx, long id, const struct timespec *abstime)
102 if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
104 if (_umtx_op(umtx, UMTX_OP_LOCK, id, 0, (void *)abstime) == -1)
110 umtx_unlock(struct umtx *umtx, long id)
112 if (atomic_cmpset_rel_ptr(&umtx->u_owner, (void *)id,
113 (void *)UMTX_UNOWNED) == 0)
114 if (_umtx_op(umtx, UMTX_OP_UNLOCK, id, 0, 0) == -1)
119 /* Unlock umtx and wait on a user address. */
122 umtx_wait(struct umtx *umtx, long id, void *uaddr)
124 if (_umtx_op(umtx, UMTX_OP_UNLOCK_AND_WAIT, id, uaddr, 0) == -1)
130 umtx_timedwait(struct umtx *umtx, long id, void *uaddr,
131 const struct timespec *abstime)
133 if (_umtx_op(umtx, UMTX_OP_UNLOCK_AND_WAIT, id, uaddr,
134 (void *)abstime) == -1)
139 /* Wake threads waiting on a user address. */
141 umtx_wake(void *uaddr, int nr_wakeup)
143 /* return how many threads were woke up, -1 if error */
144 return _umtx_op(0, UMTX_OP_WAKE, nr_wakeup, uaddr, 0);
147 #endif /* !_KERNEL */
148 #endif /* !_SYS_UMTX_H_ */