1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the author nor the names of any co-contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/types.h> 36 #include <pthread.h> 37 #include <libc_private.h> 38 #include <spinlock.h> 39 40 #include "thr_private.h" 41 42 #define MAX_SPINLOCKS 72 43 44 /* 45 * These data structures are used to trace all spinlocks 46 * in libc. 47 */ 48 struct spinlock_extra { 49 spinlock_t *owner; 50 struct umutex lock; 51 }; 52 53 static struct umutex spinlock_static_lock = DEFAULT_UMUTEX; 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 compatibility only. Spinlocks of this type 62 * are deprecated. 63 */ 64 65 void 66 __thr_spinunlock(spinlock_t *lck) 67 { 68 struct spinlock_extra *_extra; 69 70 _extra = lck->thr_extra; 71 THR_UMUTEX_UNLOCK(_get_curthread(), &_extra->lock); 72 } 73 74 void 75 __thr_spinlock(spinlock_t *lck) 76 { 77 struct spinlock_extra *_extra; 78 79 if (!_thr_isthreaded()) 80 PANIC("Spinlock called when not threaded."); 81 if (!initialized) 82 PANIC("Spinlocks not initialized."); 83 if (lck->thr_extra == NULL) 84 init_spinlock(lck); 85 _extra = lck->thr_extra; 86 THR_UMUTEX_LOCK(_get_curthread(), &_extra->lock); 87 } 88 89 static void 90 init_spinlock(spinlock_t *lck) 91 { 92 struct pthread *curthread = _get_curthread(); 93 94 THR_UMUTEX_LOCK(curthread, &spinlock_static_lock); 95 if ((lck->thr_extra == NULL) && (spinlock_count < MAX_SPINLOCKS)) { 96 lck->thr_extra = &extra[spinlock_count]; 97 _thr_umutex_init(&extra[spinlock_count].lock); 98 extra[spinlock_count].owner = lck; 99 spinlock_count++; 100 } 101 THR_UMUTEX_UNLOCK(curthread, &spinlock_static_lock); 102 if (lck->thr_extra == NULL) 103 PANIC("Warning: exceeded max spinlocks"); 104 } 105 106 void 107 _thr_spinlock_init(void) 108 { 109 int i; 110 111 _thr_umutex_init(&spinlock_static_lock); 112 if (initialized != 0) { 113 /* 114 * called after fork() to reset state of libc spin locks, 115 * it is not quite right since libc may be in inconsistent 116 * state, resetting the locks to allow current thread to be 117 * able to hold them may not help things too much, but 118 * anyway, we do our best. 119 * it is better to do pthread_atfork in libc. 120 */ 121 for (i = 0; i < spinlock_count; i++) 122 _thr_umutex_init(&extra[i].lock); 123 } else { 124 initialized = 1; 125 } 126 } 127