1 /* $NetBSD: rwsem.h,v 1.1 2014/07/16 20:59:58 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2014 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Taylor R. Campbell. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * These are not really semaphores; they are just reader/writer sleep 34 * locks, whereas what Linux calls an rwlock is a reader/writer spin 35 * lock. 36 * 37 * Notes on porting: 38 * 39 * - Linux does not have destroy_rwsem. You must add it yourself in 40 * the appropriate place. 41 */ 42 43 #ifndef _LINUX_RWSEM_H_ 44 #define _LINUX_RWSEM_H_ 45 46 #include <sys/mutex.h> 47 48 struct rw_semaphore { 49 krwlock_t rws_lock; 50 }; 51 52 static inline void 53 init_rwsem(struct rw_semaphore *rwsem) 54 { 55 56 rw_init(&rwsem->rws_lock); 57 } 58 59 static inline void 60 destroy_rwsem(struct rw_semaphore *rwsem) 61 { 62 63 rw_destroy(&rwsem->rws_lock); 64 } 65 66 static inline void 67 down_read(struct rw_semaphore *rwsem) 68 { 69 70 rw_enter(&rwsem->rws_lock, RW_READER); 71 } 72 73 static inline void 74 down_write(struct rw_semaphore *rwsem) 75 { 76 77 rw_enter(&rwsem->rws_lock, RW_WRITER); 78 } 79 80 static inline void 81 up_read(struct rw_semaphore *rwsem) 82 { 83 84 rw_exit(&rwsem->rws_lock); 85 } 86 87 static inline void 88 up_write(struct rw_semaphore *rwsem) 89 { 90 91 rw_exit(&rwsem->rws_lock); 92 } 93 94 #endif /* _LINUX_RWSEM_H_ */ 95