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
|
/*
* Copyright (c) 2017 Richard Braun.
*
* This program 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 3 of the License, or
* (at your option) any later version.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*
*
* Real-time mutual exclusion locks.
*
* A real-time mutex is similar to a regular mutex, except priority
* inheritance is unconditionally enabled.
*/
#ifndef KERN_RTMUTEX_H
#define KERN_RTMUTEX_H
#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <stdint.h>
#include <kern/atomic.h>
#include <kern/init.h>
#include <kern/macros.h>
#include <kern/rtmutex_i.h>
#include <kern/rtmutex_types.h>
struct rtmutex;
static inline bool
rtmutex_locked(const struct rtmutex *rtmutex)
{
uintptr_t owner;
owner = atomic_load(&rtmutex->owner, ATOMIC_RELAXED);
return (owner != 0);
}
/*
* Initialize a real-time mutex.
*/
static inline void
rtmutex_init(struct rtmutex *rtmutex)
{
rtmutex->owner = 0;
}
/*
* Attempt to lock the given real-time mutex.
*
* This function may not sleep.
*
* Return 0 on success, EBUSY if the mutex is already locked.
*/
static inline int
rtmutex_trylock(struct rtmutex *rtmutex)
{
uintptr_t prev_owner;
prev_owner = rtmutex_lock_fast(rtmutex);
if (unlikely(prev_owner != 0)) {
return EBUSY;
}
return 0;
}
/*
* Lock a real-time mutex.
*
* If the mutex is already locked, the calling thread sleeps until the
* mutex is unlocked, and its priority is propagated as needed to prevent
* unbounded priority inversion.
*
* A mutex can only be locked once.
*
* This function may sleep.
*/
static inline void
rtmutex_lock(struct rtmutex *rtmutex)
{
uintptr_t prev_owner;
prev_owner = rtmutex_lock_fast(rtmutex);
if (unlikely(prev_owner != 0)) {
rtmutex_lock_slow(rtmutex);
}
}
/*
* Lock a real-time mutex, with a time boundary.
*
* The time boundary is an absolute time in ticks.
*
* If successful, the mutex is locked, otherwise an error is returned.
* A mutex can only be locked once.
*
* This function may sleep.
*/
static inline int
rtmutex_timedlock(struct rtmutex *rtmutex, uint64_t ticks)
{
uintptr_t prev_owner;
prev_owner = rtmutex_lock_fast(rtmutex);
if (unlikely(prev_owner != 0)) {
return rtmutex_timedlock_slow(rtmutex, ticks);
}
return 0;
}
/*
* Unlock a real-time mutex.
*
* The mutex must be locked, and must have been locked by the calling
* thread.
*/
static inline void
rtmutex_unlock(struct rtmutex *rtmutex)
{
uintptr_t prev_owner;
prev_owner = rtmutex_unlock_fast(rtmutex);
if (unlikely(prev_owner & RTMUTEX_CONTENDED)) {
rtmutex_unlock_slow(rtmutex);
}
}
/*
* Mutex init operations. See kern/mutex.h.
*/
INIT_OP_DECLARE(rtmutex_bootstrap);
INIT_OP_DECLARE(rtmutex_setup);
#endif /* KERN_RTMUTEX_H */
|
