1 /*- 2 * Copyright (c) 2010 Isilon Systems, Inc. 3 * Copyright (c) 2010 iX Systems, Inc. 4 * Copyright (c) 2010 Panasas, Inc. 5 * Copyright (c) 2013-2016 François Tigeot 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice unmodified, this list of conditions, and the following 13 * disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 #ifndef _LINUX_KREF_H_ 30 #define _LINUX_KREF_H_ 31 32 #include <sys/refcount.h> 33 34 #include <linux/bug.h> 35 #include <linux/atomic.h> 36 #include <linux/mutex.h> 37 38 struct kref { 39 atomic_t refcount; 40 }; 41 42 static inline void 43 kref_init(struct kref *kref) 44 { 45 46 refcount_init(&kref->refcount.counter, 1); 47 } 48 49 static inline void 50 kref_get(struct kref *kref) 51 { 52 53 refcount_acquire(&kref->refcount.counter); 54 } 55 56 static inline int 57 kref_put(struct kref *kref, void (*rel)(struct kref *kref)) 58 { 59 60 if (refcount_release(&kref->refcount.counter)) { 61 rel(kref); 62 return 1; 63 } 64 return 0; 65 } 66 67 static inline int 68 kref_sub(struct kref *kref, unsigned int count, 69 void (*rel)(struct kref *kref)) 70 { 71 if (refcount_release_n(&kref->refcount.counter, count)) { 72 rel(kref); 73 return 1; 74 } 75 return 0; 76 } 77 78 /* 79 * kref_get_unless_zero: Increment refcount for object unless it is zero. 80 */ 81 static inline int __must_check kref_get_unless_zero(struct kref *kref) 82 { 83 return atomic_add_unless(&kref->refcount, 1, 0); 84 } 85 86 static inline int kref_put_mutex(struct kref *kref, 87 void (*release)(struct kref *kref), 88 struct lock *lock) 89 { 90 if (!atomic_add_unless(&kref->refcount, -1, 1)) { 91 mutex_lock(lock); 92 if (likely(atomic_dec_and_test(&kref->refcount))) { 93 release(kref); 94 return 1; 95 } 96 mutex_unlock(lock); 97 return 0; 98 } 99 100 return 0; 101 } 102 103 #endif /* _LINUX_KREF_H_ */ 104