1 /* 2 * Copyright (c) 2005 Jeffrey M. Hsu. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Jeffrey M. Hsu. 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 DragonFly Project nor the names of its 16 * contributors may be used to endorse or promote products derived 17 * from this software without specific, prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 22 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 23 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 25 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 26 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 27 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 28 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 29 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * $DragonFly: src/sys/sys/spinlock2.h,v 1.1 2005/09/16 21:50:13 dillon Exp $ 33 */ 34 35 #ifndef _SYS_SPINLOCK2_H_ 36 #define _SYS_SPINLOCK2_H_ 37 38 #include <sys/thread2.h> 39 #include <machine/atomic.h> 40 #include <machine/cpufunc.h> 41 42 #ifdef SMP 43 44 static __inline boolean_t 45 spin_trylock(struct spinlock *mtx) 46 { 47 if (atomic_swap_int(&mtx->lock, 1) == 0) 48 return (TRUE); 49 return (FALSE); 50 } 51 52 extern void spin_lock_contested(struct spinlock *mtx); 53 54 static __inline void 55 spin_lock(struct spinlock *mtx) 56 { 57 if (atomic_swap_int(&mtx->lock, 1) != 0) 58 spin_lock_contested(mtx); /* slow path */ 59 } 60 61 static __inline void 62 spin_unlock(struct spinlock *mtx) 63 { 64 cpu_sfence(); 65 mtx->lock = 0; /* non-bus-locked lock release */ 66 } 67 68 static __inline boolean_t 69 spin_is_locked(struct spinlock *mtx) 70 { 71 return (mtx->lock); 72 } 73 74 static __inline void 75 spin_init(struct spinlock *mtx) 76 { 77 mtx->lock = 0; 78 } 79 80 #else /* SMP */ 81 82 static __inline boolean_t 83 spin_trylock(struct spinlock *mtx) 84 { 85 return (TRUE); 86 } 87 88 static __inline boolean_t 89 spin_is_locked(struct spinlock *mtx) 90 { 91 return (FALSE); 92 } 93 94 static __inline void spin_lock(struct spinlock *mtx) { } 95 static __inline void spin_unlock(struct spinlock *mtx) { } 96 static __inline void spin_init(struct spinlock *mtx) { } 97 98 #endif /* SMP */ 99 100 static __inline void 101 spin_lock_crit(struct spinlock *mtx) 102 { 103 crit_enter(); 104 spin_lock(mtx); 105 } 106 107 static __inline void 108 spin_unlock_crit(struct spinlock *mtx) 109 { 110 spin_unlock(mtx); 111 crit_exit(); 112 } 113 114 #endif 115 116