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
|
/*
* Copyright 2013-2015 Olivier Houchard
* Copyright 2010-2015 Samy Al Bahra.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef CK_SPINLOCK_HCLH_H
#define CK_SPINLOCK_HCLH_H
#include <ck_cc.h>
#include <ck_pr.h>
#include <ck_stdbool.h>
#include <ck_stddef.h>
#ifndef CK_F_SPINLOCK_HCLH
#define CK_F_SPINLOCK_HCLH
struct ck_spinlock_hclh {
unsigned int wait;
unsigned int splice;
int cluster_id;
struct ck_spinlock_hclh *previous;
};
typedef struct ck_spinlock_hclh ck_spinlock_hclh_t;
CK_CC_INLINE static void
ck_spinlock_hclh_init(struct ck_spinlock_hclh **lock,
struct ck_spinlock_hclh *unowned,
int cluster_id)
{
unowned->previous = NULL;
unowned->wait = false;
unowned->splice = false;
unowned->cluster_id = cluster_id;
*lock = unowned;
ck_pr_barrier();
return;
}
CK_CC_INLINE static bool
ck_spinlock_hclh_locked(struct ck_spinlock_hclh **queue)
{
struct ck_spinlock_hclh *head;
bool r;
head = ck_pr_load_ptr(queue);
r = ck_pr_load_uint(&head->wait);
ck_pr_fence_acquire();
return r;
}
CK_CC_INLINE static void
ck_spinlock_hclh_lock(struct ck_spinlock_hclh **glob_queue,
struct ck_spinlock_hclh **local_queue,
struct ck_spinlock_hclh *thread)
{
struct ck_spinlock_hclh *previous, *local_tail;
/* Indicate to the next thread on queue that they will have to block. */
thread->wait = true;
thread->splice = false;
thread->cluster_id = (*local_queue)->cluster_id;
/* Make sure previous->previous doesn't appear to be NULL */
thread->previous = *local_queue;
/* Serialize with respect to update of local queue. */
ck_pr_fence_store_atomic();
/* Mark current request as last request. Save reference to previous request. */
previous = ck_pr_fas_ptr(local_queue, thread);
thread->previous = previous;
/* Wait until previous thread from the local queue is done with lock. */
ck_pr_fence_load();
if (previous->previous != NULL) {
while (ck_pr_load_uint(&previous->wait) == true &&
ck_pr_load_int(&previous->cluster_id) == thread->cluster_id &&
ck_pr_load_uint(&previous->splice) == false)
ck_pr_stall();
/* We're head of the global queue, we're done */
if (ck_pr_load_int(&previous->cluster_id) == thread->cluster_id &&
ck_pr_load_uint(&previous->splice) == false)
return;
}
/* Now we need to splice the local queue into the global queue. */
local_tail = ck_pr_load_ptr(local_queue);
previous = ck_pr_fas_ptr(glob_queue, local_tail);
ck_pr_store_uint(&local_tail->splice, true);
/* Wait until previous thread from the global queue is done with lock. */
while (ck_pr_load_uint(&previous->wait) == true)
ck_pr_stall();
ck_pr_fence_lock();
return;
}
CK_CC_INLINE static void
ck_spinlock_hclh_unlock(struct ck_spinlock_hclh **thread)
{
struct ck_spinlock_hclh *previous;
/*
* If there are waiters, they are spinning on the current node wait
* flag. The flag is cleared so that the successor may complete an
* acquisition. If the caller is pre-empted then the predecessor field
* may be updated by a successor's lock operation. In order to avoid
* this, save a copy of the predecessor before setting the flag.
*/
previous = thread[0]->previous;
/* We have to pay this cost anyways, use it as a compiler barrier too. */
ck_pr_fence_unlock();
ck_pr_store_uint(&(*thread)->wait, false);
/*
* Predecessor is guaranteed not to be spinning on previous request,
* so update caller to use previous structure. This allows successor
* all the time in the world to successfully read updated wait flag.
*/
*thread = previous;
return;
}
#endif /* CK_F_SPINLOCK_HCLH */
#endif /* CK_SPINLOCK_HCLH_H */
|
