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 36 struct kref { 37 atomic_t refcount; 38 }; 39 40 static inline void 41 kref_init(struct kref *kref) 42 { 43 44 refcount_init(&kref->refcount.counter, 1); 45 } 46 47 static inline void 48 kref_get(struct kref *kref) 49 { 50 51 refcount_acquire(&kref->refcount.counter); 52 } 53 54 static inline int 55 kref_put(struct kref *kref, void (*rel)(struct kref *kref)) 56 { 57 58 if (refcount_release(&kref->refcount.counter)) { 59 rel(kref); 60 return 1; 61 } 62 return 0; 63 } 64 65 static inline int 66 kref_sub(struct kref *kref, unsigned int count, 67 void (*rel)(struct kref *kref)) 68 { 69 if (refcount_release_n(&kref->refcount.counter, count)) { 70 rel(kref); 71 return 1; 72 } 73 return 0; 74 } 75 76 /* 77 * kref_get_unless_zero: Increment refcount for object unless it is zero. 78 */ 79 static inline int __must_check kref_get_unless_zero(struct kref *kref) 80 { 81 return atomic_add_unless(&kref->refcount, 1, 0); 82 } 83 84 #endif /* _LINUX_KREF_H_ */ 85