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 * $FreeBSD: src/lib/libpthread/thread/thr_spinlock.c,v 1.21 2003/12/09 02:37:40 davidxu Exp $ 33 * $DragonFly: src/lib/libthread_xu/thread/thr_spinlock.c,v 1.2 2005/03/29 19:26:20 joerg Exp $ 34 */ 35 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 "thr_private.h" 43 44 #define MAX_SPINLOCKS 20 45 46 /* 47 * These data structures are used to trace all spinlocks 48 * in libc. 49 */ 50 struct spinlock_extra { 51 spinlock_t *owner; 52 }; 53 54 static umtx_t spinlock_static_lock; 55 static struct spinlock_extra extra[MAX_SPINLOCKS]; 56 static int spinlock_count; 57 static int initialized; 58 59 static void init_spinlock(spinlock_t *lck); 60 61 /* 62 * These are for compatability only. Spinlocks of this type 63 * are deprecated. 64 */ 65 66 void 67 _spinunlock(spinlock_t *lck) 68 { 69 struct pthread *curthread = tls_get_curthread(); 70 71 THR_UMTX_UNLOCK(curthread, (umtx_t *)&lck->access_lock); 72 } 73 74 void 75 _spinlock(spinlock_t *lck) 76 { 77 struct pthread *curthread; 78 79 if (!__isthreaded) 80 PANIC("Spinlock called when not threaded."); 81 if (!initialized) 82 PANIC("Spinlocks not initialized."); 83 if (lck->fname == NULL) 84 init_spinlock(lck); 85 86 curthread = tls_get_curthread(); 87 THR_UMTX_LOCK(curthread, (umtx_t *)&lck->access_lock); 88 } 89 90 void 91 _spinlock_debug(spinlock_t *lck, char *fname, int lineno) 92 { 93 _spinlock(lck); 94 } 95 96 static void 97 init_spinlock(spinlock_t *lck) 98 { 99 static int count = 0; 100 struct pthread *curthread = tls_get_curthread(); 101 102 THR_UMTX_LOCK(curthread, &spinlock_static_lock); 103 if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) { 104 lck->fname = (char *)&extra[spinlock_count]; 105 extra[spinlock_count].owner = lck; 106 spinlock_count++; 107 } 108 THR_UMTX_UNLOCK(curthread, &spinlock_static_lock); 109 if (lck->fname == NULL && ++count < 5) 110 stderr_debug("Warning: exceeded max spinlocks"); 111 } 112 113 void 114 _thr_spinlock_init(void) 115 { 116 int i; 117 118 _thr_umtx_init(&spinlock_static_lock); 119 if (initialized != 0) { 120 /* 121 * called after fork() to reset state of libc spin locks, 122 * it is not quite right since libc may be in inconsistent 123 * state, resetting the locks to allow current thread to be 124 * able to hold them may not help things too much, but 125 * anyway, we do our best. 126 * it is better to do pthread_atfork in libc. 127 */ 128 for (i = 0; i < spinlock_count; i++) 129 _thr_umtx_init((umtx_t *)&extra[i].owner->access_lock); 130 } else { 131 initialized = 1; 132 } 133 } 134