include/sys/refcount.h

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
  24  */
  25
  26 #ifndef _SYS_REFCOUNT_H
  27 #define _SYS_REFCOUNT_H
  28
  29 #include <sys/inttypes.h>
  30 #include <sys/list.h>
  31 #include <sys/zfs_context.h>
  32
  33 #ifdef  __cplusplus
  34 extern "C" {
  35 #endif
  36
  37 /*
  38  * If the reference is held only by the calling function and not any
  39  * particular object, use FTAG (which is a string) for the holder_tag.
  40  * Otherwise, use the object that holds the reference.
  41  */
  42 #define FTAG ((char *)__func__)
  43
  44 /*
  45  * Starting with 4.11, torvalds/linux@f405df5, the linux kernel defines a
  46  * refcount_t type of its own.  The macro below effectively changes references
  47  * in the ZFS code from refcount_t to zfs_refcount_t at compile time, so that
  48  * existing code need not be altered, reducing conflicts when landing openZFS
  49  * patches.
  50  */
  51
  52 #define refcount_t      zfs_refcount_t
  53 #define refcount_add    zfs_refcount_add
  54
  55 #ifdef  ZFS_DEBUG
  56 typedef struct reference {
  57         list_node_t ref_link;
  58         void *ref_holder;
  59         uint64_t ref_number;
  60         uint8_t *ref_removed;
  61 } reference_t;
  62
  63 typedef struct refcount {
  64         kmutex_t rc_mtx;
  65         boolean_t rc_tracked;
  66         list_t rc_list;
  67         list_t rc_removed;
  68         uint64_t rc_count;
  69         uint64_t rc_removed_count;
  70 } zfs_refcount_t;
  71
  72 /* Note: refcount_t must be initialized with refcount_create[_untracked]() */
  73
  74 void refcount_create(refcount_t *rc);
  75 void refcount_create_untracked(refcount_t *rc);
  76 void refcount_create_tracked(refcount_t *rc);
  77 void refcount_destroy(refcount_t *rc);
  78 void refcount_destroy_many(refcount_t *rc, uint64_t number);
  79 int refcount_is_zero(refcount_t *rc);
  80 int64_t refcount_count(refcount_t *rc);
  81 int64_t zfs_refcount_add(refcount_t *rc, void *holder_tag);
  82 int64_t refcount_remove(refcount_t *rc, void *holder_tag);
  83 int64_t refcount_add_many(refcount_t *rc, uint64_t number, void *holder_tag);
  84 int64_t refcount_remove_many(refcount_t *rc, uint64_t number, void *holder_tag);
  85 void refcount_transfer(refcount_t *dst, refcount_t *src);
  86 void refcount_transfer_ownership(refcount_t *, void *, void *);
  87 boolean_t refcount_held(refcount_t *, void *);
  88 boolean_t refcount_not_held(refcount_t *, void *);
  89
  90 void refcount_init(void);
  91 void refcount_fini(void);
  92
  93 #else   /* ZFS_DEBUG */
  94
  95 typedef struct refcount {
  96         uint64_t rc_count;
  97 } refcount_t;
  98
  99 #define refcount_create(rc) ((rc)->rc_count = 0)
 100 #define refcount_create_untracked(rc) ((rc)->rc_count = 0)
 101 #define refcount_create_tracked(rc) ((rc)->rc_count = 0)
 102 #define refcount_destroy(rc) ((rc)->rc_count = 0)
 103 #define refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
 104 #define refcount_is_zero(rc) ((rc)->rc_count == 0)
 105 #define refcount_count(rc) ((rc)->rc_count)
 106 #define zfs_refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count)
 107 #define refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count)
 108 #define refcount_add_many(rc, number, holder) \
 109         atomic_add_64_nv(&(rc)->rc_count, number)
 110 #define refcount_remove_many(rc, number, holder) \
 111         atomic_add_64_nv(&(rc)->rc_count, -number)
 112 #define refcount_transfer(dst, src) { \
 113         uint64_t __tmp = (src)->rc_count; \
 114         atomic_add_64(&(src)->rc_count, -__tmp); \
 115         atomic_add_64(&(dst)->rc_count, __tmp); \
 116 }
 117 #define refcount_transfer_ownership(rc, current_holder, new_holder)     (void)0
 118 #define refcount_held(rc, holder)               ((rc)->rc_count > 0)
 119 #define refcount_not_held(rc, holder)           (B_TRUE)
 120
 121 #define refcount_init()
 122 #define refcount_fini()
 123
 124 #endif  /* ZFS_DEBUG */
 125
 126 #ifdef  __cplusplus
 127 }
 128 #endif
 129
 130 #endif /* _SYS_REFCOUNT_H */