kref.h revision 1.3
1 1.3 riastrad /* $NetBSD: kref.h,v 1.3 2014/07/16 20:56:25 riastradh Exp $ */ 2 1.2 riastrad 3 1.2 riastrad /*- 4 1.2 riastrad * Copyright (c) 2013 The NetBSD Foundation, Inc. 5 1.2 riastrad * All rights reserved. 6 1.2 riastrad * 7 1.2 riastrad * This code is derived from software contributed to The NetBSD Foundation 8 1.2 riastrad * by Taylor R. Campbell. 9 1.2 riastrad * 10 1.2 riastrad * Redistribution and use in source and binary forms, with or without 11 1.2 riastrad * modification, are permitted provided that the following conditions 12 1.2 riastrad * are met: 13 1.2 riastrad * 1. Redistributions of source code must retain the above copyright 14 1.2 riastrad * notice, this list of conditions and the following disclaimer. 15 1.2 riastrad * 2. Redistributions in binary form must reproduce the above copyright 16 1.2 riastrad * notice, this list of conditions and the following disclaimer in the 17 1.2 riastrad * documentation and/or other materials provided with the distribution. 18 1.2 riastrad * 19 1.2 riastrad * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 1.2 riastrad * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 1.2 riastrad * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 1.2 riastrad * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 1.2 riastrad * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 1.2 riastrad * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 1.2 riastrad * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 1.2 riastrad * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 1.2 riastrad * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 1.2 riastrad * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 1.2 riastrad * POSSIBILITY OF SUCH DAMAGE. 30 1.2 riastrad */ 31 1.2 riastrad 32 1.2 riastrad #ifndef _LINUX_KREF_H_ 33 1.2 riastrad #define _LINUX_KREF_H_ 34 1.2 riastrad 35 1.2 riastrad #include <sys/types.h> 36 1.2 riastrad #include <sys/atomic.h> 37 1.2 riastrad #include <sys/systm.h> 38 1.2 riastrad 39 1.2 riastrad #include <linux/mutex.h> 40 1.2 riastrad 41 1.2 riastrad struct kref { 42 1.2 riastrad unsigned int kr_count; 43 1.2 riastrad }; 44 1.2 riastrad 45 1.2 riastrad static inline void 46 1.2 riastrad kref_init(struct kref *kref) 47 1.2 riastrad { 48 1.2 riastrad kref->kr_count = 1; 49 1.2 riastrad } 50 1.2 riastrad 51 1.2 riastrad static inline void 52 1.2 riastrad kref_get(struct kref *kref) 53 1.2 riastrad { 54 1.2 riastrad const unsigned int count __unused = 55 1.2 riastrad atomic_inc_uint_nv(&kref->kr_count); 56 1.2 riastrad 57 1.2 riastrad KASSERTMSG((count > 1), "getting released kref"); 58 1.2 riastrad } 59 1.2 riastrad 60 1.2 riastrad static inline int 61 1.2 riastrad kref_sub(struct kref *kref, unsigned int count, void (*release)(struct kref *)) 62 1.2 riastrad { 63 1.2 riastrad unsigned int old, new; 64 1.2 riastrad 65 1.2 riastrad do { 66 1.2 riastrad old = kref->kr_count; 67 1.2 riastrad KASSERTMSG((count <= old), "overreleasing kref: %u - %u", 68 1.2 riastrad old, count); 69 1.2 riastrad new = (old - count); 70 1.2 riastrad } while (atomic_cas_uint(&kref->kr_count, old, new) != old); 71 1.2 riastrad 72 1.2 riastrad if (new == 0) { 73 1.2 riastrad (*release)(kref); 74 1.2 riastrad return 1; 75 1.2 riastrad } 76 1.2 riastrad 77 1.2 riastrad return 0; 78 1.2 riastrad } 79 1.2 riastrad 80 1.2 riastrad static inline int 81 1.2 riastrad kref_put(struct kref *kref, void (*release)(struct kref *)) 82 1.2 riastrad { 83 1.2 riastrad 84 1.2 riastrad return kref_sub(kref, 1, release); 85 1.2 riastrad } 86 1.2 riastrad 87 1.2 riastrad static inline int 88 1.2 riastrad kref_put_mutex(struct kref *kref, void (*release)(struct kref *), 89 1.2 riastrad struct mutex *interlock) 90 1.2 riastrad { 91 1.2 riastrad unsigned int old, new; 92 1.2 riastrad 93 1.2 riastrad do { 94 1.2 riastrad old = kref->kr_count; 95 1.2 riastrad KASSERT(old > 0); 96 1.2 riastrad if (old == 1) { 97 1.2 riastrad mutex_lock(interlock); 98 1.2 riastrad if (atomic_add_int_nv(&kref->kr_count, -1) == 0) { 99 1.2 riastrad (*release)(kref); 100 1.2 riastrad return 1; 101 1.2 riastrad } 102 1.2 riastrad mutex_unlock(interlock); 103 1.2 riastrad return 0; 104 1.2 riastrad } 105 1.2 riastrad new = (old - 1); 106 1.2 riastrad } while (atomic_cas_uint(&kref->kr_count, old, new) != old); 107 1.2 riastrad 108 1.2 riastrad return 0; 109 1.2 riastrad } 110 1.2 riastrad 111 1.3 riastrad /* Not native to Linux. */ 112 1.3 riastrad static inline bool 113 1.3 riastrad kref_exclusive_p(struct kref *kref) 114 1.3 riastrad { 115 1.3 riastrad 116 1.3 riastrad KASSERT(0 < kref->kr_count); 117 1.3 riastrad return (kref->kr_count == 1); 118 1.3 riastrad } 119 1.3 riastrad 120 1.2 riastrad #endif /* _LINUX_KREF_H_ */ 121
Indexes created Mon Sep 22 13:09:51 GMT 2025