xref: /illumos-gate/usr/src/uts/common/sys/mutex.h (revision cb15d5d9)
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) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
23  */
24 
25 #ifndef _SYS_MUTEX_H
26 #define	_SYS_MUTEX_H
27 
28 #ifndef	_ASM
29 #include <sys/types.h>
30 #endif
31 
32 #ifdef	__cplusplus
33 extern "C" {
34 #endif
35 
36 #ifndef	_ASM
37 
38 /*
39  * Public interface to mutual exclusion locks.  See mutex(9F) for details.
40  *
41  * The basic mutex type is MUTEX_ADAPTIVE, which is expected to be used
42  * in almost all of the kernel.  MUTEX_SPIN provides interrupt blocking
43  * and must be used in interrupt handlers above LOCK_LEVEL.  The iblock
44  * cookie argument to mutex_init() encodes the interrupt level to block.
45  * The iblock cookie must be NULL for adaptive locks.
46  *
47  * MUTEX_DEFAULT is the type usually specified (except in drivers) to
48  * mutex_init().  It is identical to MUTEX_ADAPTIVE.
49  *
50  * MUTEX_DRIVER is always used by drivers.  mutex_init() converts this to
51  * either MUTEX_ADAPTIVE or MUTEX_SPIN depending on the iblock cookie.
52  *
53  * Mutex statistics can be gathered on the fly, without rebooting or
54  * recompiling the kernel, via the lockstat driver (lockstat(7D)).
55  */
56 typedef enum {
57 	MUTEX_ADAPTIVE = 0,	/* spin if owner is running, otherwise block */
58 	MUTEX_SPIN = 1,		/* block interrupts and spin */
59 	MUTEX_DRIVER = 4,	/* driver (DDI) mutex */
60 	MUTEX_DEFAULT = 6	/* kernel default mutex */
61 } kmutex_type_t;
62 
63 typedef struct mutex {
64 #ifdef _LP64
65 	void	*_opaque[1];
66 #else
67 	void	*_opaque[2];
68 #endif
69 } kmutex_t;
70 
71 #ifdef _KERNEL
72 
73 /*
74  * A padded mutex, one per 64 byte cache line.  Use when false sharing is
75  * an issue but beware of the extra memory it uses.  Consumers may want to
76  * consider aligning their pad_mutex_t's to a cache line boundary as well.
77  */
78 typedef struct pad_mutex {
79 	kmutex_t	pad_mutex;
80 #ifdef _LP64
81 	char		pad_pad[64 - sizeof (kmutex_t)];
82 #endif
83 } pad_mutex_t;
84 
85 #define	MUTEX_HELD(x)		(mutex_owned(x))
86 #define	MUTEX_NOT_HELD(x)	(!mutex_owned(x) || panicstr || quiesce_active)
87 
88 extern	void	mutex_init(kmutex_t *, char *, kmutex_type_t, void *);
89 extern	void	mutex_destroy(kmutex_t *);
90 extern	void	mutex_enter(kmutex_t *);
91 extern	int	mutex_tryenter(kmutex_t *);
92 extern	void	mutex_exit(kmutex_t *);
93 extern	int	mutex_owned(const kmutex_t *);
94 extern	struct _kthread *mutex_owner(const kmutex_t *);
95 
96 extern  ushort_t mutex_backoff_base;
97 extern  uint_t mutex_backoff_cap;
98 extern  ushort_t mutex_cap_factor;
99 extern  uchar_t mutex_backoff_shift;
100 extern  void (*mutex_lock_delay)(uint_t);
101 extern  uint_t (*mutex_lock_backoff)(uint_t);
102 extern  void (*mutex_delay)(void);
103 extern  void mutex_delay_default(void);
104 extern  void mutex_sync(void);
105 
106 extern	void default_lock_delay(uint_t);
107 extern	uint_t default_lock_backoff(uint_t);
108 
109 #endif	/* _KERNEL */
110 
111 #endif	/* _ASM */
112 
113 #ifdef	__cplusplus
114 }
115 #endif
116 
117 #endif	/* _SYS_MUTEX_H */
118