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
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
|
/*****************************************************************************\
* 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://github.com/behlendorf/spl/>.
*
* 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>
typedef enum {
MUTEX_DEFAULT = 0,
MUTEX_SPIN = 1,
MUTEX_ADAPTIVE = 2
} kmutex_type_t;
#ifdef HAVE_MUTEX_OWNER
typedef struct mutex kmutex_t;
static inline kthread_t *
mutex_owner(kmutex_t *mp)
{
if (mp->owner)
return (mp->owner)->task;
return NULL;
}
#define mutex_owned(mp) (mutex_owner(mp) == current)
#define MUTEX_HELD(mp) mutex_owned(mp)
#undef mutex_init
#define mutex_init(mp, name, type, ibc) \
({ \
static struct lock_class_key __key; \
ASSERT(type == MUTEX_DEFAULT); \
\
__mutex_init((mp), #mp, &__key); \
})
#undef mutex_destroy
#define mutex_destroy(mp) \
({ \
VERIFY(!MUTEX_HELD(mp)); \
})
#define mutex_tryenter(mp) mutex_trylock(mp)
#define mutex_enter(mp) mutex_lock(mp)
#define mutex_exit(mp) mutex_unlock(mp)
#ifdef HAVE_GPL_ONLY_SYMBOLS
# define mutex_enter_nested(mp, sc) mutex_lock_nested(mp, sc)
#else
# define mutex_enter_nested(mp, sc) mutex_enter(mp)
#endif /* HAVE_GPL_ONLY_SYMBOLS */
#else /* HAVE_MUTEX_OWNER */
typedef struct {
struct mutex m_mutex;
kthread_t *m_owner;
} kmutex_t;
#ifdef HAVE_TASK_CURR
extern int spl_mutex_spin_max(void);
#else /* HAVE_TASK_CURR */
# define task_curr(owner) 0
# define spl_mutex_spin_max() 0
#endif /* HAVE_TASK_CURR */
#define MUTEX(mp) ((struct mutex *)(mp))
static inline kthread_t *
spl_mutex_get_owner(kmutex_t *mp)
{
return mp->m_owner;
}
static inline void
spl_mutex_set_owner(kmutex_t *mp)
{
unsigned long flags;
spin_lock_irqsave(&MUTEX(mp)->wait_lock, flags);
mp->m_owner = current;
spin_unlock_irqrestore(&MUTEX(mp)->wait_lock, flags);
}
static inline void
spl_mutex_clear_owner(kmutex_t *mp)
{
unsigned long flags;
spin_lock_irqsave(&MUTEX(mp)->wait_lock, flags);
mp->m_owner = NULL;
spin_unlock_irqrestore(&MUTEX(mp)->wait_lock, flags);
}
static inline kthread_t *
mutex_owner(kmutex_t *mp)
{
unsigned long flags;
kthread_t *owner;
spin_lock_irqsave(&MUTEX(mp)->wait_lock, flags);
owner = spl_mutex_get_owner(mp);
spin_unlock_irqrestore(&MUTEX(mp)->wait_lock, flags);
return owner;
}
#define mutex_owned(mp) (mutex_owner(mp) == current)
#define MUTEX_HELD(mp) mutex_owned(mp)
/*
* 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); \
\
__mutex_init(MUTEX(mp), #mp, &__key); \
spl_mutex_clear_owner(mp); \
})
#undef mutex_destroy
#define mutex_destroy(mp) \
({ \
VERIFY(!MUTEX_HELD(mp)); \
})
#define mutex_tryenter(mp) \
({ \
int _rc_; \
\
if ((_rc_ = mutex_trylock(MUTEX(mp))) == 1) \
spl_mutex_set_owner(mp); \
\
_rc_; \
})
/*
* Adaptive mutexs assume that the lock may be held by a task running
* on a different cpu. The expectation is that the task will drop the
* lock before leaving the head of the run queue. So the ideal thing
* to do is spin until we acquire the lock and avoid a context switch.
* However it is also possible the task holding the lock yields the
* processor with out dropping lock. In this case, we know it's going
* to be a while so we stop spinning and go to sleep waiting for the
* lock to be available. This should strike the optimum balance
* between spinning and sleeping waiting for a lock.
*/
#define mutex_enter(mp) \
({ \
kthread_t *_owner_; \
int _rc_, _count_; \
\
_rc_ = 0; \
_count_ = 0; \
_owner_ = mutex_owner(mp); \
\
while (_owner_ && task_curr(_owner_) && \
_count_ <= spl_mutex_spin_max()) { \
if ((_rc_ = mutex_trylock(MUTEX(mp)))) \
break; \
\
_count_++; \
} \
\
if (!_rc_) \
mutex_lock(MUTEX(mp)); \
\
spl_mutex_set_owner(mp); \
})
#define mutex_exit(mp) \
({ \
spl_mutex_clear_owner(mp); \
mutex_unlock(MUTEX(mp)); \
})
#ifdef HAVE_GPL_ONLY_SYMBOLS
# define mutex_enter_nested(mp, sc) \
({ \
mutex_lock_nested(MUTEX(mp, sc)); \
spl_mutex_set_owner(mp); \
})
#else
# define mutex_enter_nested(mp, sc) \
({ \
mutex_enter(mp); \
})
#endif
#endif /* HAVE_MUTEX_OWNER */
int spl_mutex_init(void);
void spl_mutex_fini(void);
#endif /* _SPL_MUTEX_H */
|
