1 /* 2 * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 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. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by John Birrell. 16 * 4. Neither the name of the author nor the names of any co-contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * $DragonFly: src/lib/libthread_xu/thread/thr_spinlock.c,v 1.3 2006/04/06 13:03:09 davidxu Exp $ 33 */ 34 35 #include "namespace.h" 36 #include <sys/types.h> 37 #include <machine/atomic.h> 38 #include <machine/tls.h> 39 #include <pthread.h> 40 #include <libc_private.h> 41 #include "spinlock.h" 42 #include "un-namespace.h" 43 44 #include "thr_private.h" 45 46 #define MAX_SPINLOCKS 128 47 48 /* 49 * These data structures are used to trace all spinlocks 50 * in libc. 51 */ 52 struct spinlock_extra { 53 spinlock_t *owner; 54 }; 55 56 static umtx_t spinlock_static_lock; 57 static struct spinlock_extra extra[MAX_SPINLOCKS]; 58 static int spinlock_count; 59 static int initialized; 60 61 static void init_spinlock(spinlock_t *lck); 62 63 /* 64 * These are for compatability only. Spinlocks of this type 65 * are deprecated. 66 */ 67 68 void 69 _spinunlock(spinlock_t *lck) 70 { 71 struct pthread *curthread = tls_get_curthread(); 72 73 THR_UMTX_UNLOCK(curthread, (volatile umtx_t *)&lck->access_lock); 74 } 75 76 void 77 _spinlock(spinlock_t *lck) 78 { 79 struct pthread *curthread; 80 81 if (!__isthreaded) 82 PANIC("Spinlock called when not threaded."); 83 if (!initialized) 84 PANIC("Spinlocks not initialized."); 85 if (lck->fname == NULL) 86 init_spinlock(lck); 87 88 curthread = tls_get_curthread(); 89 THR_UMTX_LOCK(curthread, (volatile umtx_t *)&lck->access_lock); 90 } 91 92 /* 93 * Returns 0 on success, else EBUSY 94 */ 95 int 96 _spintrylock(spinlock_t *lck) 97 { 98 struct pthread *curthread; 99 100 if (!__isthreaded) 101 PANIC("Spinlock called when not threaded."); 102 if (!initialized) 103 PANIC("Spinlocks not initialized."); 104 if (lck->fname == NULL) 105 init_spinlock(lck); 106 107 curthread = tls_get_curthread(); 108 return(THR_UMTX_TRYLOCK(curthread, 109 (volatile umtx_t *)&lck->access_lock)); 110 } 111 112 void 113 _spinlock_debug(spinlock_t *lck, char *fname __unused, int lineno __unused) 114 { 115 _spinlock(lck); 116 } 117 118 static void 119 init_spinlock(spinlock_t *lck) 120 { 121 static int count = 0; 122 struct pthread *curthread = tls_get_curthread(); 123 124 THR_UMTX_LOCK(curthread, &spinlock_static_lock); 125 if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) { 126 lck->fname = (char *)&extra[spinlock_count]; 127 extra[spinlock_count].owner = lck; 128 spinlock_count++; 129 } 130 THR_UMTX_UNLOCK(curthread, &spinlock_static_lock); 131 if (lck->fname == NULL && ++count < 5) 132 stderr_debug("Warning: exceeded max spinlocks"); 133 } 134 135 void 136 _thr_spinlock_init(void) 137 { 138 int i; 139 140 _thr_umtx_init(&spinlock_static_lock); 141 if (initialized != 0) { 142 /* 143 * called after fork() to reset state of libc spin locks, 144 * it is not quite right since libc may be in inconsistent 145 * state, resetting the locks to allow current thread to be 146 * able to hold them may not help things too much, but 147 * anyway, we do our best. 148 * it is better to do pthread_atfork in libc. 149 */ 150 for (i = 0; i < spinlock_count; i++) 151 _thr_umtx_init((volatile umtx_t *) 152 &extra[i].owner->access_lock); 153 } else { 154 initialized = 1; 155 } 156 } 157