2 * Copyright (c) 2003 Matthew Dillon <dillon@backplane.com>
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, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
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17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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26 * Implements simple shared/exclusive locks using LWKT.
28 * $DragonFly: src/sys/kern/Attic/lwkt_rwlock.c,v 1.5 2004/03/01 06:33:17 dillon Exp $
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/kernel.h>
35 #include <sys/rtprio.h>
36 #include <sys/queue.h>
39 * NOTE! called from low level boot, we cannot do anything fancy.
42 lwkt_rwlock_init(lwkt_rwlock_t lock)
44 lwkt_wait_init(&lock->rw_wait);
45 lock->rw_owner = NULL;
47 lock->rw_requests = 0;
51 lwkt_rwlock_uninit(lwkt_rwlock_t lock)
57 lwkt_exlock(lwkt_rwlock_t lock, const char *wmesg)
62 lwkt_gettoken(&ilock, &lock->rw_token);
63 gen = lock->rw_wait.wa_gen;
64 while (lock->rw_owner != curthread) {
65 if (lock->rw_owner == NULL && lock->rw_count == 0) {
66 lock->rw_owner = curthread;
70 lwkt_block(&lock->rw_wait, wmesg, &gen);
74 lwkt_reltoken(&ilock);
78 lwkt_shlock(lwkt_rwlock_t lock, const char *wmesg)
83 lwkt_gettoken(&ilock, &lock->rw_token);
84 gen = lock->rw_wait.wa_gen;
85 while (lock->rw_owner != NULL) {
87 lwkt_block(&lock->rw_wait, wmesg, &gen);
91 lwkt_reltoken(&ilock);
95 lwkt_exunlock(lwkt_rwlock_t lock)
99 lwkt_gettoken(&ilock, &lock->rw_token);
100 KASSERT(lock->rw_owner != NULL, ("lwkt_exunlock: shared lock"));
101 KASSERT(lock->rw_owner == curthread, ("lwkt_exunlock: not owner"));
102 if (--lock->rw_count == 0) {
103 lock->rw_owner = NULL;
104 if (lock->rw_requests)
105 lwkt_signal(&lock->rw_wait, 1);
107 lwkt_reltoken(&ilock);
111 lwkt_shunlock(lwkt_rwlock_t lock)
115 lwkt_gettoken(&ilock, &lock->rw_token);
116 KASSERT(lock->rw_owner == NULL, ("lwkt_shunlock: exclusive lock"));
117 if (--lock->rw_count == 0) {
118 if (lock->rw_requests)
119 lwkt_signal(&lock->rw_wait, 1);
121 lwkt_reltoken(&ilock);