1 /* Copyright (C) 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public License as
7 published by the Free Software Foundation; either version 2.1 of the
8 License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If
17 not, see <http://www.gnu.org/licenses/>. */
18
19 #include <errno.h>
20 #include <setjmp.h>
21 #include <signal.h>
22 #include <stdbool.h>
23 #include <sysdep.h>
24 #include <bits/kernel-features.h>
25 #include <pthreadP.h>
26 #include "kernel-posix-timers.h"
27
28
29 /* List of active SIGEV_THREAD timers. */
30 struct timer *__active_timer_sigev_thread;
31 /* Lock for the __active_timer_sigev_thread. */
32 pthread_mutex_t __active_timer_sigev_thread_lock = PTHREAD_MUTEX_INITIALIZER;
33
34
35 struct thread_start_data
36 {
37 void (*thrfunc) (sigval_t);
38 sigval_t sival;
39 };
40
41
42 #ifdef __NR_timer_create
43 /* Helper thread to call the user-provided function. */
44 static void *
timer_sigev_thread(void * arg)45 timer_sigev_thread (void *arg)
46 {
47 /* The parent thread has all signals blocked. This is a bit
48 surprising for user code, although valid. We unblock all
49 signals. */
50 sigset_t ss;
51 __sigemptyset (&ss);
52 INTERNAL_SYSCALL_DECL (err);
53 INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &ss, NULL, _NSIG / 8);
54
55 struct thread_start_data *td = (struct thread_start_data *) arg;
56
57 void (*thrfunc) (sigval_t) = td->thrfunc;
58 sigval_t sival = td->sival;
59
60 /* The TD object was allocated in timer_helper_thread. */
61 free (td);
62
63 /* Call the user-provided function. */
64 thrfunc (sival);
65
66 return NULL;
67 }
68
69
70 /* Helper function to support starting threads for SIGEV_THREAD. */
71 static attribute_noreturn void *
timer_helper_thread(void * arg)72 timer_helper_thread (void *arg)
73 {
74 /* Wait for the SIGTIMER signal, allowing the setXid signal, and
75 none else. */
76 sigset_t ss;
77 __sigemptyset (&ss);
78 __sigaddset (&ss, SIGTIMER);
79
80 /* Endless loop of waiting for signals. The loop is only ended when
81 the thread is canceled. */
82 while (1)
83 {
84 siginfo_t si;
85
86 /* sigwaitinfo cannot be used here, since it deletes
87 SIGCANCEL == SIGTIMER from the set. */
88
89 int oldtype = LIBC_CANCEL_ASYNC ();
90
91 /* XXX The size argument hopefully will have to be changed to the
92 real size of the user-level sigset_t. */
93 int result = INLINE_SYSCALL (rt_sigtimedwait, 4, &ss, &si, NULL,
94 _NSIG / 8);
95
96 LIBC_CANCEL_RESET (oldtype);
97
98 if (result > 0)
99 {
100 if (si.si_code == SI_TIMER)
101 {
102 struct timer *tk = (struct timer *) si.si_ptr;
103
104 /* Check the timer is still used and will not go away
105 while we are reading the values here. */
106 pthread_mutex_lock (&__active_timer_sigev_thread_lock);
107
108 struct timer *runp = __active_timer_sigev_thread;
109 while (runp != NULL)
110 if (runp == tk)
111 break;
112 else
113 runp = runp->next;
114
115 if (runp != NULL)
116 {
117 struct thread_start_data *td = malloc (sizeof (*td));
118
119 /* There is not much we can do if the allocation fails. */
120 if (td != NULL)
121 {
122 /* This is the signal we are waiting for. */
123 td->thrfunc = tk->thrfunc;
124 td->sival = tk->sival;
125
126 pthread_t th;
127 (void) pthread_create (&th, &tk->attr,
128 timer_sigev_thread, td);
129 }
130 }
131
132 pthread_mutex_unlock (&__active_timer_sigev_thread_lock);
133 }
134 else if (si.si_code == SI_TKILL)
135 /* The thread is canceled. */
136 pthread_exit (NULL);
137 }
138 }
139 }
140
141
142 /* Control variable for helper thread creation. */
143 pthread_once_t __helper_once attribute_hidden;
144
145
146 /* TID of the helper thread. */
147 pid_t __helper_tid attribute_hidden;
148
149
150 /* Reset variables so that after a fork a new helper thread gets started. */
151 static void
reset_helper_control(void)152 reset_helper_control (void)
153 {
154 __helper_once = PTHREAD_ONCE_INIT;
155 __helper_tid = 0;
156 }
157
158
159 void
160 attribute_hidden
__start_helper_thread(void)161 __start_helper_thread (void)
162 {
163 /* The helper thread needs only very little resources
164 and should go away automatically when canceled. */
165 pthread_attr_t attr;
166 (void) pthread_attr_init (&attr);
167 (void) pthread_attr_setstacksize (&attr, PTHREAD_STACK_MIN);
168
169 /* Block all signals in the helper thread but SIGSETXID. To do this
170 thoroughly we temporarily have to block all signals here. The
171 helper can lose wakeups if SIGCANCEL is not blocked throughout,
172 but sigfillset omits it SIGSETXID. So, we add SIGCANCEL back
173 explicitly here. */
174 sigset_t ss;
175 sigset_t oss;
176 sigfillset (&ss);
177 __sigaddset (&ss, SIGCANCEL);
178 INTERNAL_SYSCALL_DECL (err);
179 INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &ss, &oss, _NSIG / 8);
180
181 /* Create the helper thread for this timer. */
182 pthread_t th;
183 int res = pthread_create (&th, &attr, timer_helper_thread, NULL);
184 if (res == 0)
185 /* We managed to start the helper thread. */
186 __helper_tid = ((struct pthread *) th)->tid;
187
188 /* Restore the signal mask. */
189 INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &oss, NULL,
190 _NSIG / 8);
191
192 /* No need for the attribute anymore. */
193 (void) pthread_attr_destroy (&attr);
194
195 /* We have to make sure that after fork()ing a new helper thread can
196 be created. */
197 pthread_atfork (NULL, NULL, reset_helper_control);
198 }
199 #endif
200
201 #ifndef __ASSUME_POSIX_TIMERS
202 # include <nptl/sysdeps/pthread/timer_routines.c>
203 #endif
204