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 1.1 2005/02/01 12:38:27 davidxu Exp $ 34 */ 35 36 #include <sys/types.h> 37 #include <machine/atomic.h> 38 #include <pthread.h> 39 #include <libc_private.h> 40 #include "spinlock.h" 41 #include "thr_private.h" 42 43 #define MAX_SPINLOCKS 20 44 45 /* 46 * These data structures are used to trace all spinlocks 47 * in libc. 48 */ 49 struct spinlock_extra { 50 spinlock_t *owner; 51 }; 52 53 static umtx_t spinlock_static_lock; 54 static struct spinlock_extra extra[MAX_SPINLOCKS]; 55 static int spinlock_count; 56 static int initialized; 57 58 static void init_spinlock(spinlock_t *lck); 59 60 /* 61 * These are for compatability only. Spinlocks of this type 62 * are deprecated. 63 */ 64 65 void 66 _spinunlock(spinlock_t *lck) 67 { 68 THR_UMTX_UNLOCK(_get_curthread(), (umtx_t *)&lck->access_lock); 69 } 70 71 void 72 _spinlock(spinlock_t *lck) 73 { 74 if (!__isthreaded) 75 PANIC("Spinlock called when not threaded."); 76 if (!initialized) 77 PANIC("Spinlocks not initialized."); 78 if (lck->fname == NULL) 79 init_spinlock(lck); 80 THR_UMTX_LOCK(_get_curthread(), (umtx_t *)&lck->access_lock); 81 } 82 83 void 84 _spinlock_debug(spinlock_t *lck, char *fname, int lineno) 85 { 86 _spinlock(lck); 87 } 88 89 static void 90 init_spinlock(spinlock_t *lck) 91 { 92 static int count = 0; 93 94 THR_UMTX_LOCK(_get_curthread(), &spinlock_static_lock); 95 if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) { 96 lck->fname = (char *)&extra[spinlock_count]; 97 extra[spinlock_count].owner = lck; 98 spinlock_count++; 99 } 100 THR_UMTX_UNLOCK(_get_curthread(), &spinlock_static_lock); 101 if (lck->fname == NULL && ++count < 5) 102 stderr_debug("Warning: exceeded max spinlocks"); 103 } 104 105 void 106 _thr_spinlock_init(void) 107 { 108 int i; 109 110 _thr_umtx_init(&spinlock_static_lock); 111 if (initialized != 0) { 112 /* 113 * called after fork() to reset state of libc spin locks, 114 * it is not quite right since libc may be in inconsistent 115 * state, resetting the locks to allow current thread to be 116 * able to hold them may not help things too much, but 117 * anyway, we do our best. 118 * it is better to do pthread_atfork in libc. 119 */ 120 for (i = 0; i < spinlock_count; i++) 121 _thr_umtx_init((umtx_t *)&extra[i].owner->access_lock); 122 } else { 123 initialized = 1; 124 } 125 } 126