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      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 2007 Sun Microsystems, Inc.  All rights reserved.
     23  * Use is subject to license terms.
     24  */
     25 
     26 #ifndef	_SYS_REFCOUNT_H
     27 #define	_SYS_REFCOUNT_H
     28 
     29 #pragma ident	"@(#)refcount.h	1.3	07/08/02 SMI"
     30 
     31 #include <sys/inttypes.h>
     32 #include <sys/list.h>
     33 #include <sys/zfs_context.h>
     34 
     35 #ifdef	__cplusplus
     36 extern "C" {
     37 #endif
     38 
     39 /*
     40  * If the reference is held only by the calling function and not any
     41  * particular object, use FTAG (which is a string) for the holder_tag.
     42  * Otherwise, use the object that holds the reference.
     43  */
     44 #define	FTAG ((char *)__func__)
     45 
     46 #if defined(DEBUG) || !defined(_KERNEL)
     47 typedef struct reference {
     48 	list_node_t ref_link;
     49 	void *ref_holder;
     50 	uint64_t ref_number;
     51 	uint8_t *ref_removed;
     52 } reference_t;
     53 
     54 typedef struct refcount {
     55 	kmutex_t rc_mtx;
     56 	list_t rc_list;
     57 	list_t rc_removed;
     58 	int64_t rc_count;
     59 	int64_t rc_removed_count;
     60 } refcount_t;
     61 
     62 /* Note: refcount_t must be initialized with refcount_create() */
     63 
     64 void refcount_create(refcount_t *rc);
     65 void refcount_destroy(refcount_t *rc);
     66 void refcount_destroy_many(refcount_t *rc, uint64_t number);
     67 int refcount_is_zero(refcount_t *rc);
     68 int64_t refcount_count(refcount_t *rc);
     69 int64_t refcount_add(refcount_t *rc, void *holder_tag);
     70 int64_t refcount_remove(refcount_t *rc, void *holder_tag);
     71 int64_t refcount_add_many(refcount_t *rc, uint64_t number, void *holder_tag);
     72 int64_t refcount_remove_many(refcount_t *rc, uint64_t number, void *holder_tag);
     73 
     74 void refcount_init(void);
     75 void refcount_fini(void);
     76 
     77 #else /* DEBUG */
     78 
     79 typedef struct refcount {
     80 	uint64_t rc_count;
     81 } refcount_t;
     82 
     83 #define	refcount_create(rc) ((rc)->rc_count = 0)
     84 #define	refcount_destroy(rc) ((rc)->rc_count = 0)
     85 #define	refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
     86 #define	refcount_is_zero(rc) ((rc)->rc_count == 0)
     87 #define	refcount_count(rc) ((rc)->rc_count)
     88 #define	refcount_add(rc, holder) atomic_add_64_nv(&(rc)->rc_count, 1)
     89 #define	refcount_remove(rc, holder) atomic_add_64_nv(&(rc)->rc_count, -1)
     90 #define	refcount_add_many(rc, number, holder) \
     91 	atomic_add_64_nv(&(rc)->rc_count, number)
     92 #define	refcount_remove_many(rc, number, holder) \
     93 	atomic_add_64_nv(&(rc)->rc_count, -number)
     94 
     95 #define	refcount_init()
     96 #define	refcount_fini()
     97 
     98 #endif /* DEBUG */
     99 
    100 #ifdef	__cplusplus
    101 }
    102 #endif
    103 
    104 #endif /* _SYS_REFCOUNT_H */
    105