1 /* 2 * Copyright (c) 2004 Michael Telahun Makonnen <mtm@FreeBSD.Org> 3 * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 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. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by John Birrell. 17 * 4. Neither the name of the author nor the names of any co-contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $FreeBSD$ 34 * 35 */ 36 37 #include <sys/types.h> 38 #include <machine/atomic.h> 39 40 #include <stdlib.h> 41 #include <stdio.h> 42 #include <string.h> 43 #include <sched.h> 44 #include <pthread.h> 45 #include <unistd.h> 46 47 #include <libc_private.h> 48 49 #include "thr_private.h" 50 51 #define THR_SPIN_MAGIC 0xdadadada 52 #define THR_SPIN_UNOWNED (void *)0 53 #define MAGIC_TEST_RETURN_ON_FAIL(l) \ 54 do { \ 55 if ((l) == NULL || (l)->s_magic != THR_SPIN_MAGIC) \ 56 return (EINVAL); \ 57 } while(0) 58 59 __weak_reference(_pthread_spin_destroy, pthread_spin_destroy); 60 __weak_reference(_pthread_spin_init, pthread_spin_init); 61 __weak_reference(_pthread_spin_lock, pthread_spin_lock); 62 __weak_reference(_pthread_spin_trylock, pthread_spin_trylock); 63 __weak_reference(_pthread_spin_unlock, pthread_spin_unlock); 64 65 int 66 _pthread_spin_destroy(pthread_spinlock_t *lock) 67 { 68 MAGIC_TEST_RETURN_ON_FAIL((*lock)); 69 if ((*lock)->s_owner == THR_SPIN_UNOWNED) { 70 (*lock)->s_magic = 0; 71 free((*lock)); 72 *lock = NULL; 73 return (0); 74 } 75 return (EBUSY); 76 } 77 78 int 79 _pthread_spin_init(pthread_spinlock_t *lock, int pshared) 80 { 81 struct pthread_spinlock *s; 82 83 s = (struct pthread_spinlock *)malloc(sizeof(struct pthread_spinlock)); 84 if (s == NULL) 85 return (ENOMEM); 86 s->s_magic = THR_SPIN_MAGIC; 87 s->s_owner = THR_SPIN_UNOWNED; 88 *lock = s; 89 return (0); 90 } 91 92 /* 93 * If the caller sets nonblocking to 1, this function will return 94 * immediately without acquiring the lock it is owned by another thread. 95 * If set to 0, it will keep spinning until it acquires the lock. 96 */ 97 int 98 _pthread_spin_lock(pthread_spinlock_t *lock) 99 { 100 MAGIC_TEST_RETURN_ON_FAIL(*lock); 101 if ((*lock)->s_owner == curthread) 102 return (EDEADLK); 103 while (atomic_cmpset_acq_ptr(&(*lock)->s_owner, THR_SPIN_UNOWNED, 104 (void *)curthread) != 1) 105 ; /* SPIN */ 106 return (0); 107 } 108 109 int 110 _pthread_spin_trylock(pthread_spinlock_t *lock) 111 { 112 MAGIC_TEST_RETURN_ON_FAIL(*lock); 113 if (atomic_cmpset_acq_ptr(&(*lock)->s_owner, THR_SPIN_UNOWNED, 114 (void *)curthread) == 1) 115 return (0); 116 return (EBUSY); 117 } 118 119 int 120 _pthread_spin_unlock(pthread_spinlock_t *lock) 121 { 122 MAGIC_TEST_RETURN_ON_FAIL(*lock); 123 if (atomic_cmpset_rel_ptr(&(*lock)->s_owner, (void *)curthread, 124 THR_SPIN_UNOWNED) == 1) 125 return (0); 126 return (EPERM); 127 } 128 129 void 130 _spinunlock(spinlock_t *lck) 131 { 132 if (umtx_unlock((struct umtx *)lck, curthread->thr_id)) 133 abort(); 134 } 135 136 /* 137 * Lock a location for the running thread. Yield to allow other 138 * threads to run if this thread is blocked because the lock is 139 * not available. Note that this function does not sleep. It 140 * assumes that the lock will be available very soon. 141 */ 142 void 143 _spinlock(spinlock_t *lck) 144 { 145 if (umtx_lock((struct umtx *)lck, curthread->thr_id)) 146 abort(); 147 } 148 149 int 150 _spintrylock(spinlock_t *lck) 151 { 152 int error; 153 154 error = umtx_lock((struct umtx *)lck, curthread->thr_id); 155 if (error != 0 && error != EBUSY) 156 abort(); 157 return (error); 158 } 159 160 /* 161 * Lock a location for the running thread. Yield to allow other 162 * threads to run if this thread is blocked because the lock is 163 * not available. Note that this function does not sleep. It 164 * assumes that the lock will be available very soon. 165 * 166 * This function checks if the running thread has already locked the 167 * location, warns if this occurs and creates a thread dump before 168 * returning. 169 */ 170 void 171 _spinlock_debug(spinlock_t *lck, char *fname, int lineno) 172 { 173 if (umtx_lock((struct umtx *)lck, curthread->thr_id)) 174 abort(); 175 } 176