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 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/atomic.h> 35 #include <linux/mutex.h> 36 37 struct kref { 38 atomic_t refcount; 39 }; 40 41 static inline void 42 kref_init(struct kref *kref) 43 { 44 45 refcount_init(&kref->refcount.counter, 1); 46 } 47 48 static inline void 49 kref_get(struct kref *kref) 50 { 51 52 refcount_acquire(&kref->refcount.counter); 53 } 54 55 static inline int 56 kref_put(struct kref *kref, void (*rel)(struct kref *kref)) 57 { 58 59 if (refcount_release(&kref->refcount.counter)) { 60 rel(kref); 61 return 1; 62 } 63 return 0; 64 } 65 66 static inline int 67 kref_sub(struct kref *kref, unsigned int count, 68 void (*rel)(struct kref *kref)) 69 { 70 if (refcount_release_n(&kref->refcount.counter, count)) { 71 rel(kref); 72 return 1; 73 } 74 return 0; 75 } 76 77 /* 78 * kref_get_unless_zero: Increment refcount for object unless it is zero. 79 */ 80 static inline int __must_check kref_get_unless_zero(struct kref *kref) 81 { 82 return atomic_add_unless(&kref->refcount, 1, 0); 83 } 84 85 static inline int kref_put_mutex(struct kref *kref, 86 void (*release)(struct kref *kref), 87 struct lock *lock) 88 { 89 if (!atomic_add_unless(&kref->refcount, -1, 1)) { 90 mutex_lock(lock); 91 if (likely(atomic_dec_and_test(&kref->refcount))) { 92 release(kref); 93 return 1; 94 } 95 mutex_unlock(lock); 96 return 0; 97 } 98 99 return 0; 100 } 101 102 #endif /* _LINUX_KREF_H_ */ 103