mutex.h revision 1.8 
1/*	$OpenBSD: mutex.h,v 1.8 2018/01/13 15:18:11 mpi Exp $	*/
2
3/*
4 * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. The name of the author may not be used to endorse or promote products
14 *    derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
17 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
18 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
19 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20 * EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#ifndef _MACHINE_MUTEX_H_
29#define _MACHINE_MUTEX_H_
30
31#include <sys/_lock.h>
32
33struct mutex {
34	volatile void *mtx_owner;
35	int mtx_wantipl;
36	int mtx_oldipl;
37#ifdef WITNESS
38	struct lock_object mtx_lock_obj;
39#endif
40};
41
42/*
43 * To prevent lock ordering problems with the kernel lock, we need to
44 * make sure we block all interrupts that can grab the kernel lock.
45 * The simplest way to achieve this is to make sure mutexes always
46 * raise the interrupt priority level to the highest level that has
47 * interrupts that grab the kernel lock.
48 */
49#ifdef MULTIPROCESSOR
50#define __MUTEX_IPL(ipl) \
51    (((ipl) > IPL_NONE && (ipl) < IPL_MPFLOOR) ? IPL_MPFLOOR : (ipl))
52#else
53#define __MUTEX_IPL(ipl) (ipl)
54#endif
55
56#ifdef WITNESS
57#define MUTEX_INITIALIZER_FLAGS(ipl, name, flags) \
58	{ NULL, __MUTEX_IPL((ipl)), IPL_NONE, MTX_LO_INITIALIZER(name, flags) }
59#else
60#define MUTEX_INITIALIZER_FLAGS(ipl, name, flags) \
61	{ NULL, __MUTEX_IPL((ipl)), IPL_NONE }
62#endif
63
64void __mtx_init(struct mutex *, int);
65#define _mtx_init(mtx, ipl) __mtx_init((mtx), __MUTEX_IPL((ipl)))
66
67#ifdef DIAGNOSTIC
68#define MUTEX_ASSERT_LOCKED(mtx) do {					\
69	if ((mtx)->mtx_owner != curcpu())				\
70		panic("mutex %p not held in %s", (mtx), __func__);	\
71} while (0)
72
73#define MUTEX_ASSERT_UNLOCKED(mtx) do {					\
74	if ((mtx)->mtx_owner == curcpu())				\
75		panic("mutex %p held in %s", (mtx), __func__);		\
76} while (0)
77#else
78#define MUTEX_ASSERT_LOCKED(mtx) do { } while (0)
79#define MUTEX_ASSERT_UNLOCKED(mtx) do { } while (0)
80#endif
81
82#define MUTEX_LOCK_OBJECT(mtx)	(&(mtx)->mtx_lock_obj)
83#define MUTEX_OLDIPL(mtx)	(mtx)->mtx_oldipl
84
85#endif	/* _MACHINE_MUTEX_H_ */
86