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
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
|
/* Thread creation.
Copyright (C) 2000, 2002, 2005, 2007 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 <assert.h>
#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <bits/atomic.h>
#include <pt-internal.h>
#ifdef HAVE_USELOCALE
# include <locale.h>
#endif
/* The total number of pthreads currently active. This is defined
here since it would be really stupid to have a threads-using
program that doesn't call `pthread_create'. */
__atomic_t __pthread_total;
/* The entry-point for new threads. */
static void
entry_point (void *(*start_routine)(void *), void *arg)
{
#ifdef HAVE_USELOCALE
/* A fresh thread needs to be bound to the global locale. */
uselocale (LC_GLOBAL_LOCALE);
#endif
pthread_exit (start_routine (arg));
}
/* Create a thread with attributes given by ATTR, executing
START_ROUTINE with argument ARG. */
int
pthread_create (pthread_t *thread, const pthread_attr_t *attr,
void *(*start_routine)(void *), void *arg)
{
int err;
struct __pthread *pthread;
err = __pthread_create_internal (&pthread, attr, start_routine, arg);
if (! err)
*thread = pthread->thread;
return err;
}
/* Internal version of pthread_create. See comment in
pt-internal.h. */
int
__pthread_create_internal (struct __pthread **thread,
const pthread_attr_t *attr,
void *(*start_routine)(void *), void *arg)
{
int err;
struct __pthread *pthread;
const struct __pthread_attr *setup;
sigset_t sigset;
/* Allocate a new thread structure. */
err = __pthread_alloc (&pthread);
if (err)
goto failed;
/* Use the default attributes if ATTR is NULL. */
setup = attr ? attr : &__pthread_default_attr;
/* Initialize the thread state. */
pthread->state = (setup->detachstate == PTHREAD_CREATE_DETACHED
? PTHREAD_DETACHED : PTHREAD_JOINABLE);
/* If the user supplied a stack, it is not our responsibility to
setup a stack guard. */
if (setup->stackaddr)
pthread->guardsize = 0;
else
pthread->guardsize = (setup->guardsize <= setup->stacksize
? setup->guardsize : setup->stacksize);
/* Find a stack. There are several scenarios: if a detached thread
kills itself, it has no way to deallocate its stack, thus it
leaves PTHREAD->stack set to true. We try to reuse it here,
however, if the user supplied a stack, we cannot use the old one.
Right now, we simply deallocate it. */
if (pthread->stack)
{
if (setup->stackaddr != __pthread_default_attr.stackaddr)
{
__pthread_stack_dealloc (pthread->stackaddr,
pthread->stacksize);
pthread->stackaddr = setup->stackaddr;
pthread->stacksize = setup->stacksize;
}
}
else
{
err = __pthread_stack_alloc (&pthread->stackaddr,
setup->stacksize);
if (err)
goto failed_stack_alloc;
pthread->stacksize = setup->stacksize;
pthread->stack = 1;
}
/* Allocate the kernel thread and other required resources. */
err = __pthread_thread_alloc (pthread);
if (err)
goto failed_thread_alloc;
#ifdef ENABLE_TLS
pthread->tcb = _dl_allocate_tls (NULL);
if (!pthread->tcb)
goto failed_thread_tls_alloc;
pthread->tcb->tcb = pthread->tcb;
#endif /* ENABLE_TLS */
/* And initialize the rest of the machine context. This may include
additional machine- and system-specific initializations that
prove convenient. */
err = __pthread_setup (pthread, entry_point, start_routine, arg);
if (err)
goto failed_setup;
/* Initialize the system-specific signal state for the new
thread. */
err = __pthread_sigstate_init (pthread);
if (err)
goto failed_sigstate;
/* Set the new thread's signal mask and set the pending signals to
empty. POSIX says: "The signal mask shall be inherited from the
creating thread. The set of signals pending for the new thread
shall be empty." If the currnet thread is not a pthread then we
just inherit the process' sigmask. */
if (__pthread_num_threads == 1)
err = sigprocmask (0, 0, &sigset);
else
err = __pthread_sigstate (_pthread_self (), 0, 0, &sigset, 0);
assert_perror (err);
err = __pthread_sigstate (pthread, SIG_SETMASK, &sigset, 0, 1);
assert_perror (err);
/* Increase the total number of threads. We do this before actually
starting the new thread, since the new thread might immediately
call `pthread_exit' which decreases the number of threads and
calls `exit' if the number of threads reaches zero. Increasing
the number of threads from within the new thread isn't an option
since this thread might return and call `pthread_exit' before the
new thread runs. */
__atomic_inc (&__pthread_total);
/* Store a pointer to this thread in the thread ID lookup table. We
could use __thread_setid, however, we only lock for reading as no
other thread should be using this entry (we also assume that the
store is atomic). */
pthread_rwlock_rdlock (&__pthread_threads_lock);
__pthread_threads[pthread->thread - 1] = pthread;
pthread_rwlock_unlock (&__pthread_threads_lock);
/* At this point it is possible to guess our pthread ID. We have to
make sure that all functions taking a pthread_t argument can
handle the fact that this thread isn't really running yet. */
/* Schedule the new thread. */
err = __pthread_thread_start (pthread);
if (err)
goto failed_starting;
/* At this point the new thread is up and running. */
*thread = pthread;
return 0;
failed_starting:
__pthread_setid (pthread->thread, NULL);
__atomic_dec (&__pthread_total);
failed_sigstate:
__pthread_sigstate_destroy (pthread);
failed_setup:
#ifdef ENABLE_TLS
_dl_deallocate_tls (pthread->tcb, 1);
failed_thread_tls_alloc:
#endif /* ENABLE_TLS */
__pthread_thread_dealloc (pthread);
__pthread_thread_halt (pthread, 0);
failed_thread_alloc:
__pthread_stack_dealloc (pthread->stackaddr, pthread->stacksize);
pthread->stack = 0;
failed_stack_alloc:
__pthread_dealloc (pthread);
failed:
return err;
}
|
