refcount.h revision 1.3
1 1.3 riastrad /* $NetBSD: refcount.h,v 1.3 2021/12/19 11:52:08 riastradh Exp $ */ 2 1.2 riastrad 3 1.2 riastrad /*- 4 1.2 riastrad * Copyright (c) 2020 The NetBSD Foundation, Inc. 5 1.2 riastrad * All rights reserved. 6 1.2 riastrad * 7 1.2 riastrad * Redistribution and use in source and binary forms, with or without 8 1.2 riastrad * modification, are permitted provided that the following conditions 9 1.2 riastrad * are met: 10 1.2 riastrad * 1. Redistributions of source code must retain the above copyright 11 1.2 riastrad * notice, this list of conditions and the following disclaimer. 12 1.2 riastrad * 2. Redistributions in binary form must reproduce the above copyright 13 1.2 riastrad * notice, this list of conditions and the following disclaimer in the 14 1.2 riastrad * documentation and/or other materials provided with the distribution. 15 1.2 riastrad * 16 1.2 riastrad * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 1.2 riastrad * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 1.2 riastrad * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 1.2 riastrad * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 1.2 riastrad * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 1.2 riastrad * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 1.2 riastrad * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 1.2 riastrad * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 1.2 riastrad * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 1.2 riastrad * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 1.2 riastrad * POSSIBILITY OF SUCH DAMAGE. 27 1.2 riastrad */ 28 1.2 riastrad 29 1.2 riastrad #ifndef _LINUX_REFCOUNT_H_ 30 1.2 riastrad #define _LINUX_REFCOUNT_H_ 31 1.2 riastrad 32 1.2 riastrad #include <linux/atomic.h> 33 1.2 riastrad #include <linux/mutex.h> 34 1.2 riastrad #include <linux/spinlock.h> 35 1.2 riastrad 36 1.2 riastrad typedef struct refcount refcount_t; 37 1.2 riastrad 38 1.2 riastrad struct refcount { 39 1.2 riastrad atomic_t rc_count; 40 1.2 riastrad }; 41 1.2 riastrad 42 1.2 riastrad static inline void 43 1.2 riastrad refcount_set(struct refcount *rc, int n) 44 1.2 riastrad { 45 1.2 riastrad atomic_set(&rc->rc_count, n); 46 1.2 riastrad } 47 1.2 riastrad 48 1.2 riastrad static inline void 49 1.2 riastrad refcount_inc(struct refcount *rc) 50 1.2 riastrad { 51 1.2 riastrad atomic_inc(&rc->rc_count); 52 1.2 riastrad } 53 1.2 riastrad 54 1.2 riastrad static inline int __must_check 55 1.2 riastrad refcount_inc_not_zero(struct refcount *rc) 56 1.2 riastrad { 57 1.2 riastrad unsigned old, new; 58 1.2 riastrad 59 1.2 riastrad do { 60 1.2 riastrad old = atomic_read(&rc->rc_count); 61 1.2 riastrad if (old == 0) 62 1.2 riastrad break; 63 1.2 riastrad new = old + 1; 64 1.2 riastrad } while (atomic_cmpxchg(&rc->rc_count, old, new) != old); 65 1.2 riastrad 66 1.2 riastrad return old; 67 1.2 riastrad } 68 1.2 riastrad 69 1.2 riastrad static inline bool __must_check 70 1.2 riastrad refcount_dec_and_test(struct refcount *rc) 71 1.2 riastrad { 72 1.2 riastrad unsigned old, new; 73 1.2 riastrad 74 1.2 riastrad do { 75 1.2 riastrad old = atomic_read(&rc->rc_count); 76 1.2 riastrad KASSERT(old); 77 1.2 riastrad new = old - 1; 78 1.2 riastrad } while (atomic_cmpxchg(&rc->rc_count, old, new) != old); 79 1.2 riastrad 80 1.2 riastrad return old == 1; 81 1.2 riastrad } 82 1.2 riastrad 83 1.2 riastrad static inline bool __must_check 84 1.2 riastrad refcount_dec_and_lock_irqsave(struct refcount *rc, struct spinlock *lock, 85 1.2 riastrad unsigned long *flagsp) 86 1.2 riastrad { 87 1.2 riastrad 88 1.3 riastrad return atomic_dec_and_lock_irqsave(&rc->rc_count, lock, *flagsp); 89 1.2 riastrad } 90 1.2 riastrad 91 1.2 riastrad static inline bool __must_check 92 1.2 riastrad refcount_dec_and_mutex_lock(struct refcount *rc, struct mutex *lock) 93 1.2 riastrad { 94 1.2 riastrad unsigned old, new; 95 1.2 riastrad 96 1.2 riastrad do { 97 1.2 riastrad old = atomic_read(&rc->rc_count); 98 1.2 riastrad KASSERT(old); 99 1.2 riastrad if (old == 1) { 100 1.2 riastrad mutex_lock(lock); 101 1.2 riastrad if (atomic_dec_return(&rc->rc_count) == 0) 102 1.2 riastrad return true; 103 1.2 riastrad mutex_unlock(lock); 104 1.2 riastrad return false; 105 1.2 riastrad } 106 1.2 riastrad new = old - 1; 107 1.2 riastrad } while (atomic_cmpxchg(&rc->rc_count, old, new) != old); 108 1.2 riastrad 109 1.2 riastrad KASSERT(old != 1); 110 1.2 riastrad KASSERT(new != 0); 111 1.2 riastrad return false; 112 1.2 riastrad } 113 1.2 riastrad 114 1.2 riastrad #endif /* _LINUX_REFCOUNT_H_ */ 115
Indexes created Sun Sep 21 16:09:51 GMT 2025