xref: /titanic_41/usr/src/uts/common/sys/rwlock_impl.h (revision 7c478bd95313f5f23a4c958a745db2134aa03244)
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, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #ifndef _SYS_RWLOCK_IMPL_H
28 #define	_SYS_RWLOCK_IMPL_H
29 
30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
31 
32 /*
33  * Implementation-private definitions for readers/writer locks.
34  */
35 
36 #ifndef _ASM
37 
38 #include <sys/rwlock.h>
39 
40 #ifdef	__cplusplus
41 extern "C" {
42 #endif
43 
44 typedef struct rwlock_impl {
45 	uintptr_t	rw_wwwh;	/* waiters, write wanted, hold count */
46 } rwlock_impl_t;
47 
48 #endif	/* _ASM */
49 
50 #define	RW_HAS_WAITERS		1
51 #define	RW_WRITE_WANTED		2
52 #define	RW_WRITE_LOCKED		4
53 #define	RW_READ_LOCK		8
54 #define	RW_WRITE_LOCK(thread)	((uintptr_t)(thread) | RW_WRITE_LOCKED)
55 #define	RW_HOLD_COUNT		(-RW_READ_LOCK)
56 #define	RW_HOLD_COUNT_SHIFT	3		/* log2(RW_READ_LOCK) */
57 #define	RW_READ_COUNT		RW_HOLD_COUNT
58 #define	RW_OWNER		RW_HOLD_COUNT
59 #define	RW_LOCKED		RW_HOLD_COUNT
60 #define	RW_WRITE_CLAIMED	(RW_WRITE_LOCKED | RW_WRITE_WANTED)
61 #define	RW_DOUBLE_LOCK		(RW_WRITE_LOCK(0) | RW_READ_LOCK)
62 
63 /*
64  * These macros are used by both the implementation of rw_*() routines and
65  * by the implementation of the rwlock-related DTrace subroutines.  (DTrace
66  * cannot make calls into the rw_*() routines; it must use the macros.)
67  */
68 #define	_RW_READ_HELD(rwlp, tmp)					\
69 	((((tmp) = ((rwlock_impl_t *)(rwlp))->rw_wwwh) & RW_LOCKED) &&	\
70 	!((tmp) & RW_WRITE_LOCKED))
71 
72 #define	_RW_WRITE_HELD(rwlp)						\
73 	((((rwlock_impl_t *)(rwlp))->rw_wwwh &				\
74 	(RW_OWNER | RW_WRITE_LOCKED)) == RW_WRITE_LOCK(curthread))
75 
76 #define	_RW_LOCK_HELD(rwlp)						\
77 	((((rwlock_impl_t *)(rwlp))->rw_wwwh & RW_LOCKED) ? 1 : 0)
78 
79 #define	_RW_ISWRITER(rwlp)						\
80 	((((rwlock_impl_t *)(rwlp))->rw_wwwh & RW_WRITE_CLAIMED) ? 1 : 0)
81 
82 #ifdef	__cplusplus
83 }
84 #endif
85 
86 #endif	/* _SYS_RWLOCK_IMPL_H */
87