sys/rrwlock.h

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/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#ifndef _SYS_RR_RW_LOCK_H
#define _SYS_RR_RW_LOCK_H

#pragma ident   "%Z%%M% %I%     %E% SMI"

#ifdef  __cplusplus
extern "C" {
#endif

#include <sys/zfs_context.h>
#include <sys/refcount.h>

typedef struct rrwlock {
        kmutex_t        rr_lock;
        kcondvar_t      rr_cv;
        kthread_t       *rr_writer;
        refcount_t      rr_anon_rcount;
        refcount_t      rr_linked_rcount;
        boolean_t       rr_writer_wanted;
} rrwlock_t;

/*
 * 'tag' is used in reference counting tracking.  The
 * 'tag' must be the same in a rrw_enter() as in its
 * corresponding rrw_exit().
 */
void rrw_init(rrwlock_t *rrl);
void rrw_destroy(rrwlock_t *rrl);
void rrw_enter(rrwlock_t *rrl, krw_t rw, void *tag);
void rrw_exit(rrwlock_t *rrl, void *tag);
boolean_t rrw_held(rrwlock_t *rrl, krw_t rw);

#define RRW_READ_HELD(x)        rrw_held(x, RW_READER)
#define RRW_WRITE_HELD(x)       rrw_held(x, RW_WRITER)

#ifdef  __cplusplus
}
#endif

#endif  /* _SYS_RR_RW_LOCK_H */