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/types.h> 33 #include <pthread.h> 34 #include <libc_private.h> 35 #include <spinlock.h> 36 37 #include "thr_private.h" 38 39 #define MAX_SPINLOCKS 72 40 41 /* 42 * These data structures are used to trace all spinlocks 43 * in libc. 44 */ 45 struct spinlock_extra { 46 spinlock_t *owner; 47 struct umutex lock; 48 }; 49 50 static struct umutex spinlock_static_lock = DEFAULT_UMUTEX; 51 static struct spinlock_extra extra[MAX_SPINLOCKS]; 52 static int spinlock_count; 53 static int initialized; 54 55 static void init_spinlock(spinlock_t *lck); 56 57 /* 58 * These are for compatibility only. Spinlocks of this type 59 * are deprecated. 60 */ 61 62 void 63 __thr_spinunlock(spinlock_t *lck) 64 { 65 struct spinlock_extra *_extra; 66 67 _extra = lck->thr_extra; 68 THR_UMUTEX_UNLOCK(_get_curthread(), &_extra->lock); 69 } 70 71 void 72 __thr_spinlock(spinlock_t *lck) 73 { 74 struct spinlock_extra *_extra; 75 76 if (!_thr_isthreaded()) 77 PANIC("Spinlock called when not threaded."); 78 if (!initialized) 79 PANIC("Spinlocks not initialized."); 80 if (lck->thr_extra == NULL) 81 init_spinlock(lck); 82 _extra = lck->thr_extra; 83 THR_UMUTEX_LOCK(_get_curthread(), &_extra->lock); 84 } 85 86 static void 87 init_spinlock(spinlock_t *lck) 88 { 89 struct pthread *curthread = _get_curthread(); 90 91 THR_UMUTEX_LOCK(curthread, &spinlock_static_lock); 92 if ((lck->thr_extra == NULL) && (spinlock_count < MAX_SPINLOCKS)) { 93 lck->thr_extra = &extra[spinlock_count]; 94 _thr_umutex_init(&extra[spinlock_count].lock); 95 extra[spinlock_count].owner = lck; 96 spinlock_count++; 97 } 98 THR_UMUTEX_UNLOCK(curthread, &spinlock_static_lock); 99 if (lck->thr_extra == NULL) 100 PANIC("Warning: exceeded max spinlocks"); 101 } 102 103 void 104 _thr_spinlock_init(void) 105 { 106 int i; 107 108 _thr_umutex_init(&spinlock_static_lock); 109 if (initialized != 0) { 110 /* 111 * called after fork() to reset state of libc spin locks, 112 * it is not quite right since libc may be in inconsistent 113 * state, resetting the locks to allow current thread to be 114 * able to hold them may not help things too much, but 115 * anyway, we do our best. 116 * it is better to do pthread_atfork in libc. 117 */ 118 for (i = 0; i < spinlock_count; i++) 119 _thr_umutex_init(&extra[i].lock); 120 } else { 121 initialized = 1; 122 } 123 } 124