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. Neither the name of the author nor the names of any co-contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 */ 30 31 #include <sys/types.h> 32 #include <machine/atomic.h> 33 #include <machine/tls.h> 34 #include <pthread.h> 35 #include <libc_private.h> 36 #include "spinlock.h" 37 38 #include "thr_private.h" 39 40 #define MAX_SPINLOCKS 256 41 42 /* 43 * These data structures are used to trace all spinlocks 44 * in libc. 45 */ 46 struct spinlock_extra { 47 spinlock_t *owner; 48 }; 49 50 static umtx_t spinlock_static_lock; 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 compatability only. Spinlocks of this type 59 * are deprecated. 60 */ 61 62 void 63 _spinunlock(spinlock_t *lck) 64 { 65 struct pthread *curthread = tls_get_curthread(); 66 67 THR_UMTX_UNLOCK(curthread, (volatile umtx_t *)&lck->access_lock); 68 } 69 70 void 71 _spinlock(spinlock_t *lck) 72 { 73 struct pthread *curthread; 74 75 if (!__isthreaded) 76 PANIC("Spinlock called when not threaded."); 77 if (!initialized) 78 PANIC("Spinlocks not initialized."); 79 if (lck->fname == NULL) 80 init_spinlock(lck); 81 82 curthread = tls_get_curthread(); 83 THR_UMTX_LOCK(curthread, (volatile umtx_t *)&lck->access_lock); 84 } 85 86 /* 87 * Returns 0 on success, else EBUSY 88 */ 89 int 90 _spintrylock(spinlock_t *lck) 91 { 92 struct pthread *curthread; 93 94 if (!__isthreaded) 95 PANIC("Spinlock called when not threaded."); 96 if (!initialized) 97 PANIC("Spinlocks not initialized."); 98 if (lck->fname == NULL) 99 init_spinlock(lck); 100 101 curthread = tls_get_curthread(); 102 return(THR_UMTX_TRYLOCK(curthread, 103 (volatile umtx_t *)&lck->access_lock)); 104 } 105 106 void 107 _spinlock_debug(spinlock_t *lck, char *fname __unused, int lineno __unused) 108 { 109 _spinlock(lck); 110 } 111 112 static void 113 init_spinlock(spinlock_t *lck) 114 { 115 static int count = 0; 116 struct pthread *curthread = tls_get_curthread(); 117 118 THR_UMTX_LOCK(curthread, &spinlock_static_lock); 119 if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) { 120 lck->fname = (char *)&extra[spinlock_count]; 121 extra[spinlock_count].owner = lck; 122 spinlock_count++; 123 } 124 THR_UMTX_UNLOCK(curthread, &spinlock_static_lock); 125 if (lck->fname == NULL && ++count < 5) 126 stderr_debug("Warning: exceeded max spinlocks"); 127 } 128 129 void 130 _thr_spinlock_init(void) 131 { 132 int i; 133 134 _thr_umtx_init(&spinlock_static_lock); 135 if (initialized != 0) { 136 /* 137 * called after fork() to reset state of libc spin locks, 138 * it is not quite right since libc may be in inconsistent 139 * state, resetting the locks to allow current thread to be 140 * able to hold them may not help things too much, but 141 * anyway, we do our best. 142 * it is better to do pthread_atfork in libc. 143 */ 144 for (i = 0; i < spinlock_count; i++) 145 _thr_umtx_init((volatile umtx_t *) 146 &extra[i].owner->access_lock); 147 } else { 148 initialized = 1; 149 } 150 } 151