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
|
/* Try to Lock a mutex. Generic version.
Copyright (C) 2002, 2005, 2008 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <pthread.h>
#include <pt-internal.h>
#define LOSE do { * (int *) 0 = 0; } while (1)
/* Lock MUTEX, return EBUSY if we can't get it. */
int
__pthread_mutex_trylock (struct __pthread_mutex *mutex)
{
int err;
struct __pthread *self;
const struct __pthread_mutexattr *attr = mutex->attr;
if (attr == __PTHREAD_ERRORCHECK_MUTEXATTR)
attr = &__pthread_errorcheck_mutexattr;
if (attr == __PTHREAD_RECURSIVE_MUTEXATTR)
attr = &__pthread_recursive_mutexattr;
__pthread_spin_lock (&mutex->__lock);
if (__pthread_spin_trylock (&mutex->__held) == 0)
/* Acquired the lock. */
{
#if defined(ALWAYS_TRACK_MUTEX_OWNER)
#ifndef NDEBUG
self = _pthread_self ();
if (self)
/* The main thread may take a lock before the library is fully
initialized, in particular, before the main thread has a
TCB. */
{
assert (! mutex->owner);
mutex->owner = _pthread_self ();
}
#endif
#endif
if (attr)
switch (attr->mutex_type)
{
case PTHREAD_MUTEX_NORMAL:
break;
case PTHREAD_MUTEX_RECURSIVE:
mutex->locks = 1;
case PTHREAD_MUTEX_ERRORCHECK:
mutex->owner = _pthread_self ();
break;
default:
LOSE;
}
__pthread_spin_unlock (&mutex->__lock);
return 0;
}
err = EBUSY;
if (attr)
{
self = _pthread_self ();
switch (attr->mutex_type)
{
case PTHREAD_MUTEX_NORMAL:
break;
case PTHREAD_MUTEX_ERRORCHECK:
/* We could check if MUTEX->OWNER is SELF, however, POSIX
does not permit pthread_mutex_trylock to return EDEADLK
instead of EBUSY, only pthread_mutex_lock. */
break;
case PTHREAD_MUTEX_RECURSIVE:
if (mutex->owner == self)
{
mutex->locks ++;
err = 0;
}
break;
default:
LOSE;
}
}
__pthread_spin_unlock (&mutex->__lock);
return err;
}
strong_alias (__pthread_mutex_trylock, _pthread_mutex_trylock);
strong_alias (__pthread_mutex_trylock, pthread_mutex_trylock);
|
