kref.h revision 1.2.6.2
1 1.2.6.2 yamt /* $NetBSD: kref.h,v 1.2.6.2 2014/05/22 11:40:56 yamt Exp $ */ 2 1.2.6.2 yamt 3 1.2.6.2 yamt /*- 4 1.2.6.2 yamt * Copyright (c) 2013 The NetBSD Foundation, Inc. 5 1.2.6.2 yamt * All rights reserved. 6 1.2.6.2 yamt * 7 1.2.6.2 yamt * This code is derived from software contributed to The NetBSD Foundation 8 1.2.6.2 yamt * by Taylor R. Campbell. 9 1.2.6.2 yamt * 10 1.2.6.2 yamt * Redistribution and use in source and binary forms, with or without 11 1.2.6.2 yamt * modification, are permitted provided that the following conditions 12 1.2.6.2 yamt * are met: 13 1.2.6.2 yamt * 1. Redistributions of source code must retain the above copyright 14 1.2.6.2 yamt * notice, this list of conditions and the following disclaimer. 15 1.2.6.2 yamt * 2. Redistributions in binary form must reproduce the above copyright 16 1.2.6.2 yamt * notice, this list of conditions and the following disclaimer in the 17 1.2.6.2 yamt * documentation and/or other materials provided with the distribution. 18 1.2.6.2 yamt * 19 1.2.6.2 yamt * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 1.2.6.2 yamt * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 1.2.6.2 yamt * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 1.2.6.2 yamt * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 1.2.6.2 yamt * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 1.2.6.2 yamt * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 1.2.6.2 yamt * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 1.2.6.2 yamt * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 1.2.6.2 yamt * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 1.2.6.2 yamt * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 1.2.6.2 yamt * POSSIBILITY OF SUCH DAMAGE. 30 1.2.6.2 yamt */ 31 1.2.6.2 yamt 32 1.2.6.2 yamt #ifndef _LINUX_KREF_H_ 33 1.2.6.2 yamt #define _LINUX_KREF_H_ 34 1.2.6.2 yamt 35 1.2.6.2 yamt #include <sys/types.h> 36 1.2.6.2 yamt #include <sys/atomic.h> 37 1.2.6.2 yamt #include <sys/systm.h> 38 1.2.6.2 yamt 39 1.2.6.2 yamt #include <linux/mutex.h> 40 1.2.6.2 yamt 41 1.2.6.2 yamt struct kref { 42 1.2.6.2 yamt unsigned int kr_count; 43 1.2.6.2 yamt }; 44 1.2.6.2 yamt 45 1.2.6.2 yamt static inline void 46 1.2.6.2 yamt kref_init(struct kref *kref) 47 1.2.6.2 yamt { 48 1.2.6.2 yamt kref->kr_count = 1; 49 1.2.6.2 yamt } 50 1.2.6.2 yamt 51 1.2.6.2 yamt static inline void 52 1.2.6.2 yamt kref_get(struct kref *kref) 53 1.2.6.2 yamt { 54 1.2.6.2 yamt const unsigned int count __unused = 55 1.2.6.2 yamt atomic_inc_uint_nv(&kref->kr_count); 56 1.2.6.2 yamt 57 1.2.6.2 yamt KASSERTMSG((count > 1), "getting released kref"); 58 1.2.6.2 yamt } 59 1.2.6.2 yamt 60 1.2.6.2 yamt static inline int 61 1.2.6.2 yamt kref_sub(struct kref *kref, unsigned int count, void (*release)(struct kref *)) 62 1.2.6.2 yamt { 63 1.2.6.2 yamt unsigned int old, new; 64 1.2.6.2 yamt 65 1.2.6.2 yamt do { 66 1.2.6.2 yamt old = kref->kr_count; 67 1.2.6.2 yamt KASSERTMSG((count <= old), "overreleasing kref: %u - %u", 68 1.2.6.2 yamt old, count); 69 1.2.6.2 yamt new = (old - count); 70 1.2.6.2 yamt } while (atomic_cas_uint(&kref->kr_count, old, new) != old); 71 1.2.6.2 yamt 72 1.2.6.2 yamt if (new == 0) { 73 1.2.6.2 yamt (*release)(kref); 74 1.2.6.2 yamt return 1; 75 1.2.6.2 yamt } 76 1.2.6.2 yamt 77 1.2.6.2 yamt return 0; 78 1.2.6.2 yamt } 79 1.2.6.2 yamt 80 1.2.6.2 yamt static inline int 81 1.2.6.2 yamt kref_put(struct kref *kref, void (*release)(struct kref *)) 82 1.2.6.2 yamt { 83 1.2.6.2 yamt 84 1.2.6.2 yamt return kref_sub(kref, 1, release); 85 1.2.6.2 yamt } 86 1.2.6.2 yamt 87 1.2.6.2 yamt static inline int 88 1.2.6.2 yamt kref_put_mutex(struct kref *kref, void (*release)(struct kref *), 89 1.2.6.2 yamt struct mutex *interlock) 90 1.2.6.2 yamt { 91 1.2.6.2 yamt unsigned int old, new; 92 1.2.6.2 yamt 93 1.2.6.2 yamt do { 94 1.2.6.2 yamt old = kref->kr_count; 95 1.2.6.2 yamt KASSERT(old > 0); 96 1.2.6.2 yamt if (old == 1) { 97 1.2.6.2 yamt mutex_lock(interlock); 98 1.2.6.2 yamt if (atomic_add_int_nv(&kref->kr_count, -1) == 0) { 99 1.2.6.2 yamt (*release)(kref); 100 1.2.6.2 yamt return 1; 101 1.2.6.2 yamt } 102 1.2.6.2 yamt mutex_unlock(interlock); 103 1.2.6.2 yamt return 0; 104 1.2.6.2 yamt } 105 1.2.6.2 yamt new = (old - 1); 106 1.2.6.2 yamt } while (atomic_cas_uint(&kref->kr_count, old, new) != old); 107 1.2.6.2 yamt 108 1.2.6.2 yamt return 0; 109 1.2.6.2 yamt } 110 1.2.6.2 yamt 111 1.2.6.2 yamt #endif /* _LINUX_KREF_H_ */ 112
Indexes created Thu Oct 02 01:09:59 GMT 2025