blob: 1919b62a9935d1b46312de0418bc853fe03dad69 (
plain)
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
|
/*
* Copyright (c) 2013 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/>.
*
*
* Lockless synchronization.
*/
#ifndef _KERN_LLSYNC_H
#define _KERN_LLSYNC_H
#include <kern/list.h>
#include <kern/macros.h>
#include <kern/llsync_i.h>
#include <kern/thread.h>
#include <kern/work.h>
#include <machine/mb.h>
/*
* Safely assign a pointer.
*
* This macro enforces memory ordering. It should be used to reference
* objects once they're completely built, so that readers accessing the
* pointer obtain consistent data.
*/
#define llsync_assign_ptr(ptr, value) \
MACRO_BEGIN \
mb_store(); \
(ptr) = (value); \
MACRO_END
/*
* Safely access a pointer.
*
* No memory barrier, rely on data dependency to enforce ordering.
*/
#define llsync_read_ptr(ptr) (ptr)
static inline void
llsync_read_enter(void)
{
thread_preempt_disable();
}
static inline void
llsync_read_exit(void)
{
thread_preempt_enable();
}
/*
* Report that a processor has reached a checkpoint.
*
* Called during context switch.
*/
static inline void
llsync_checkin(unsigned int cpu)
{
llsync_cpus[cpu].checked = 1;
}
/*
* Initialize the llsync module.
*/
void llsync_setup(void);
/*
* Report that a processor will be regularly checking in.
*
* Registered processors perform checkpoint commits and receive checkpoint
* reset interrupts.
*/
void llsync_register_cpu(unsigned int cpu);
/*
* Report that a processor has entered a state in which checking in becomes
* irrelevant (e.g. the idle loop).
*/
void llsync_unregister_cpu(unsigned int cpu);
/*
* Commit a pending checkpoint.
*
* Checking in is a light processor-local operation. Committing a checkpoint
* is a heavier global one, and is performed less often, normally during the
* system timer interrupt.
*/
void llsync_commit_checkpoint(unsigned int cpu);
/*
* Reset the checkpoint pending state of a processor.
*
* Called from interrupt context.
*/
void llsync_reset_checkpoint(unsigned int cpu);
/*
* Defer an operation until all existing read-side references are dropped,
* without blocking.
*/
void llsync_defer(struct work *work);
/*
* Wait for all existing read-side references to be dropped.
*
* This function sleeps, and may do so for a moderately long duration (a few
* system timer ticks).
*/
void llsync_wait(void);
#endif /* _KERN_LLSYNC_H */
|