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
|
/* sem_waitcommon -- wait on a semaphore, shared code.
Copyright (C) 2003-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <sysdep.h>
#include <futex-internal.h>
#include <internaltypes.h>
#include <semaphore.h>
#include <sys/time.h>
#include <pthreadP.h>
#include <shlib-compat.h>
#include <atomic.h>
static void
__sem_wait_32_finish (struct new_sem *sem);
static void
__sem_wait_cleanup (void *arg)
{
struct new_sem *sem = (struct new_sem *) arg;
__sem_wait_32_finish (sem);
}
/* Wait until at least one token is available, possibly with a timeout.
This is in a separate function in order to make sure gcc
puts the call site into an exception region, and thus the
cleanups get properly run. TODO still necessary? Other futex_wait
users don't seem to need it. */
static int
__attribute__ ((noinline))
do_futex_wait (struct new_sem *sem, const struct timespec *abstime)
{
int err;
err = futex_abstimed_wait_cancelable (&sem->value, SEM_NWAITERS_MASK,
abstime, sem->private);
return err;
}
/* Fast path: Try to grab a token without blocking. */
static int
__new_sem_wait_fast (struct new_sem *sem, int definitive_result)
{
unsigned int v;
int ret = 0;
__sparc32_atomic_do_lock24(&sem->pad);
v = sem->value;
if ((v >> SEM_VALUE_SHIFT) == 0)
ret = -1;
else
sem->value = v - (1 << SEM_VALUE_SHIFT);
__sparc32_atomic_do_unlock24(&sem->pad);
return ret;
}
/* Slow path that blocks. */
static int
__attribute__ ((noinline))
__new_sem_wait_slow (struct new_sem *sem, const struct timespec *abstime)
{
unsigned int v;
int err = 0;
__sparc32_atomic_do_lock24(&sem->pad);
sem->nwaiters++;
pthread_cleanup_push (__sem_wait_cleanup, sem);
/* Wait for a token to be available. Retry until we can grab one. */
v = sem->value;
do
{
if (!(v & SEM_NWAITERS_MASK))
sem->value = v | SEM_NWAITERS_MASK;
/* If there is no token, wait. */
if ((v >> SEM_VALUE_SHIFT) == 0)
{
__sparc32_atomic_do_unlock24(&sem->pad);
err = do_futex_wait(sem, abstime);
if (err == ETIMEDOUT || err == EINTR)
{
__set_errno (err);
err = -1;
goto error;
}
err = 0;
__sparc32_atomic_do_lock24(&sem->pad);
/* We blocked, so there might be a token now. */
v = sem->value;
}
}
/* If there is no token, we must not try to grab one. */
while ((v >> SEM_VALUE_SHIFT) == 0);
sem->value = v - (1 << SEM_VALUE_SHIFT);
__sparc32_atomic_do_unlock24(&sem->pad);
error:
pthread_cleanup_pop (0);
__sem_wait_32_finish (sem);
return err;
}
/* Stop being a registered waiter (non-64b-atomics code only). */
static void
__sem_wait_32_finish (struct new_sem *sem)
{
__sparc32_atomic_do_lock24(&sem->pad);
if (--sem->nwaiters == 0)
sem->value &= ~SEM_NWAITERS_MASK;
__sparc32_atomic_do_unlock24(&sem->pad);
}
|
