1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
/*
* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
* Copyright (C) 2007 The Regents of the University of California.
* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
* UCRL-CODE-235197
*
* This file is part of the SPL, Solaris Porting Layer.
* For details, see <http://zfsonlinux.org/>.
*
* The SPL is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* The SPL is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with the SPL. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _SPL_MUTEX_H
#define _SPL_MUTEX_H
#include <sys/types.h>
#include <linux/mutex.h>
#include <linux/lockdep.h>
#include <linux/compiler_compat.h>
typedef enum {
MUTEX_DEFAULT = 0,
MUTEX_SPIN = 1,
MUTEX_ADAPTIVE = 2,
MUTEX_NOLOCKDEP = 3
} kmutex_type_t;
typedef struct {
struct mutex m_mutex;
spinlock_t m_lock; /* used for serializing mutex_exit */
kthread_t *m_owner;
#ifdef CONFIG_LOCKDEP
kmutex_type_t m_type;
#endif /* CONFIG_LOCKDEP */
} kmutex_t;
#define MUTEX(mp) (&((mp)->m_mutex))
static inline void
spl_mutex_set_owner(kmutex_t *mp)
{
mp->m_owner = current;
}
static inline void
spl_mutex_clear_owner(kmutex_t *mp)
{
mp->m_owner = NULL;
}
#define mutex_owner(mp) (READ_ONCE((mp)->m_owner))
#define mutex_owned(mp) (mutex_owner(mp) == current)
#define MUTEX_HELD(mp) mutex_owned(mp)
#define MUTEX_NOT_HELD(mp) (!MUTEX_HELD(mp))
#ifdef CONFIG_LOCKDEP
static inline void
spl_mutex_set_type(kmutex_t *mp, kmutex_type_t type)
{
mp->m_type = type;
}
static inline void
spl_mutex_lockdep_off_maybe(kmutex_t *mp) \
{ \
if (mp && mp->m_type == MUTEX_NOLOCKDEP) \
lockdep_off(); \
}
static inline void
spl_mutex_lockdep_on_maybe(kmutex_t *mp) \
{ \
if (mp && mp->m_type == MUTEX_NOLOCKDEP) \
lockdep_on(); \
}
#else /* CONFIG_LOCKDEP */
#define spl_mutex_set_type(mp, type)
#define spl_mutex_lockdep_off_maybe(mp)
#define spl_mutex_lockdep_on_maybe(mp)
#endif /* CONFIG_LOCKDEP */
/*
* The following functions must be a #define and not static inline.
* This ensures that the native linux mutex functions (lock/unlock)
* will be correctly located in the users code which is important
* for the built in kernel lock analysis tools
*/
#undef mutex_init
#define mutex_init(mp, name, type, ibc) \
{ \
static struct lock_class_key __key; \
ASSERT(type == MUTEX_DEFAULT || type == MUTEX_NOLOCKDEP); \
\
__mutex_init(MUTEX(mp), (name) ? (#name) : (#mp), &__key); \
spin_lock_init(&(mp)->m_lock); \
spl_mutex_clear_owner(mp); \
spl_mutex_set_type(mp, type); \
}
#undef mutex_destroy
#define mutex_destroy(mp) \
{ \
VERIFY3P(mutex_owner(mp), ==, NULL); \
}
/* BEGIN CSTYLED */
#define mutex_tryenter(mp) \
({ \
int _rc_; \
\
spl_mutex_lockdep_off_maybe(mp); \
if ((_rc_ = mutex_trylock(MUTEX(mp))) == 1) \
spl_mutex_set_owner(mp); \
spl_mutex_lockdep_on_maybe(mp); \
\
_rc_; \
})
/* END CSTYLED */
#define NESTED_SINGLE 1
#ifdef CONFIG_DEBUG_LOCK_ALLOC
#define mutex_enter_nested(mp, subclass) \
{ \
ASSERT3P(mutex_owner(mp), !=, current); \
spl_mutex_lockdep_off_maybe(mp); \
mutex_lock_nested(MUTEX(mp), (subclass)); \
spl_mutex_lockdep_on_maybe(mp); \
spl_mutex_set_owner(mp); \
}
#else /* CONFIG_DEBUG_LOCK_ALLOC */
#define mutex_enter_nested(mp, subclass) \
{ \
ASSERT3P(mutex_owner(mp), !=, current); \
spl_mutex_lockdep_off_maybe(mp); \
mutex_lock(MUTEX(mp)); \
spl_mutex_lockdep_on_maybe(mp); \
spl_mutex_set_owner(mp); \
}
#endif /* CONFIG_DEBUG_LOCK_ALLOC */
#define mutex_enter(mp) mutex_enter_nested((mp), 0)
/*
* The reason for the spinlock:
*
* The Linux mutex is designed with a fast-path/slow-path design such that it
* does not guarantee serialization upon itself, allowing a race where latter
* acquirers finish mutex_unlock before former ones.
*
* The race renders it unsafe to be used for serializing the freeing of an
* object in which the mutex is embedded, where the latter acquirer could go
* on to free the object while the former one is still doing mutex_unlock and
* causing memory corruption.
*
* However, there are many places in ZFS where the mutex is used for
* serializing object freeing, and the code is shared among other OSes without
* this issue. Thus, we need the spinlock to force the serialization on
* mutex_exit().
*
* See http://lwn.net/Articles/575477/ for the information about the race.
*/
#define mutex_exit(mp) \
{ \
spl_mutex_clear_owner(mp); \
spin_lock(&(mp)->m_lock); \
spl_mutex_lockdep_off_maybe(mp); \
mutex_unlock(MUTEX(mp)); \
spl_mutex_lockdep_on_maybe(mp); \
spin_unlock(&(mp)->m_lock); \
/* NOTE: do not dereference mp after this point */ \
}
#endif /* _SPL_MUTEX_H */
|
