xref: /illumos-gate/usr/src/uts/common/sys/rwlock_impl.h (revision 2d6eb4a5)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#ifndef _SYS_RWLOCK_IMPL_H
#define	_SYS_RWLOCK_IMPL_H

/*
 * Implementation-private definitions for readers/writer locks.
 */

#ifndef _ASM

#include <sys/rwlock.h>

#ifdef	__cplusplus
extern "C" {
#endif

typedef struct rwlock_impl {
	uintptr_t	rw_wwwh;	/* waiters, write wanted, hold count */
} rwlock_impl_t;

#endif	/* _ASM */

#define	RW_HAS_WAITERS		1
#define	RW_WRITE_WANTED		2
#define	RW_WRITE_LOCKED		4
#define	RW_READ_LOCK		8
#define	RW_WRITE_LOCK(thread)	((uintptr_t)(thread) | RW_WRITE_LOCKED)
#define	RW_HOLD_COUNT		(-RW_READ_LOCK)
#define	RW_HOLD_COUNT_SHIFT	3		/* log2(RW_READ_LOCK) */
#define	RW_READ_COUNT		RW_HOLD_COUNT
#define	RW_OWNER		RW_HOLD_COUNT
#define	RW_LOCKED		RW_HOLD_COUNT
#define	RW_WRITE_CLAIMED	(RW_WRITE_LOCKED | RW_WRITE_WANTED)
#define	RW_DOUBLE_LOCK		(RW_WRITE_LOCK(0) | RW_READ_LOCK)

/*
 * These macros are used by both the implementation of rw_*() routines and
 * by the implementation of the rwlock-related DTrace subroutines.  (DTrace
 * cannot make calls into the rw_*() routines; it must use the macros.)
 */
#define	_RW_READ_HELD(rwlp, tmp)					\
	((((tmp) = ((rwlock_impl_t *)(rwlp))->rw_wwwh) & RW_LOCKED) &&	\
	!((tmp) & RW_WRITE_LOCKED))

#define	_RW_WRITE_HELD(rwlp)						\
	((((rwlock_impl_t *)(rwlp))->rw_wwwh &				\
	(RW_OWNER | RW_WRITE_LOCKED)) == RW_WRITE_LOCK(curthread))

#define	_RW_LOCK_HELD(rwlp)						\
	((((rwlock_impl_t *)(rwlp))->rw_wwwh & RW_LOCKED) ? 1 : 0)

#define	_RW_ISWRITER(rwlp)						\
	((((rwlock_impl_t *)(rwlp))->rw_wwwh & RW_WRITE_CLAIMED) ? 1 : 0)

#ifdef	__cplusplus
}
#endif

#endif	/* _SYS_RWLOCK_IMPL_H */