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f7a9f785 | 1 | /* Copyright (C) 2003-2016 Free Software Foundation, Inc. |
09402f5b UD |
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 | |
59ba27a6 PE |
16 | License along with the GNU C Library; see the file COPYING.LIB. If |
17 | not, see <http://www.gnu.org/licenses/>. */ | |
09402f5b | 18 | |
d7ba1313 | 19 | #include <errno.h> |
09402f5b UD |
20 | #include <setjmp.h> |
21 | #include <signal.h> | |
22 | #include <stdbool.h> | |
c6bb095e | 23 | #include <sysdep-cancel.h> |
5f5004df | 24 | #include <nptl/pthreadP.h> |
09402f5b UD |
25 | #include "kernel-posix-timers.h" |
26 | ||
27 | ||
f160a450 UD |
28 | /* List of active SIGEV_THREAD timers. */ |
29 | struct timer *__active_timer_sigev_thread; | |
30 | /* Lock for the __active_timer_sigev_thread. */ | |
31 | pthread_mutex_t __active_timer_sigev_thread_lock = PTHREAD_MUTEX_INITIALIZER; | |
32 | ||
33 | ||
a6375d11 UD |
34 | struct thread_start_data |
35 | { | |
36 | void (*thrfunc) (sigval_t); | |
37 | sigval_t sival; | |
38 | }; | |
39 | ||
40 | ||
09402f5b UD |
41 | /* Helper thread to call the user-provided function. */ |
42 | static void * | |
43 | timer_sigev_thread (void *arg) | |
44 | { | |
fa0e226b UD |
45 | /* The parent thread has all signals blocked. This is a bit |
46 | surprising for user code, although valid. We unblock all | |
47 | signals. */ | |
48 | sigset_t ss; | |
49 | sigemptyset (&ss); | |
50 | INTERNAL_SYSCALL_DECL (err); | |
51 | INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &ss, NULL, _NSIG / 8); | |
52 | ||
a6375d11 UD |
53 | struct thread_start_data *td = (struct thread_start_data *) arg; |
54 | ||
55 | void (*thrfunc) (sigval_t) = td->thrfunc; | |
56 | sigval_t sival = td->sival; | |
57 | ||
58 | /* The TD object was allocated in timer_helper_thread. */ | |
59 | free (td); | |
09402f5b UD |
60 | |
61 | /* Call the user-provided function. */ | |
a6375d11 | 62 | thrfunc (sival); |
09402f5b UD |
63 | |
64 | return NULL; | |
65 | } | |
66 | ||
67 | ||
68 | /* Helper function to support starting threads for SIGEV_THREAD. */ | |
5f5004df UD |
69 | static void * |
70 | timer_helper_thread (void *arg) | |
09402f5b | 71 | { |
fd4af664 UD |
72 | /* Wait for the SIGTIMER signal, allowing the setXid signal, and |
73 | none else. */ | |
09402f5b | 74 | sigset_t ss; |
09402f5b | 75 | sigemptyset (&ss); |
fd4af664 | 76 | __sigaddset (&ss, SIGTIMER); |
09402f5b UD |
77 | |
78 | /* Endless loop of waiting for signals. The loop is only ended when | |
79 | the thread is canceled. */ | |
80 | while (1) | |
81 | { | |
82 | siginfo_t si; | |
83 | ||
d7ba1313 UD |
84 | /* sigwaitinfo cannot be used here, since it deletes |
85 | SIGCANCEL == SIGTIMER from the set. */ | |
86 | ||
d7ba1313 UD |
87 | /* XXX The size argument hopefully will have to be changed to the |
88 | real size of the user-level sigset_t. */ | |
c6bb095e | 89 | int result = SYSCALL_CANCEL (rt_sigtimedwait, &ss, &si, NULL, _NSIG / 8); |
d7ba1313 UD |
90 | |
91 | if (result > 0) | |
09402f5b | 92 | { |
e7608d77 UD |
93 | if (si.si_code == SI_TIMER) |
94 | { | |
95 | struct timer *tk = (struct timer *) si.si_ptr; | |
a6375d11 | 96 | |
f160a450 UD |
97 | /* Check the timer is still used and will not go away |
98 | while we are reading the values here. */ | |
99 | pthread_mutex_lock (&__active_timer_sigev_thread_lock); | |
a6375d11 | 100 | |
f160a450 UD |
101 | struct timer *runp = __active_timer_sigev_thread; |
102 | while (runp != NULL) | |
103 | if (runp == tk) | |
104 | break; | |
105 | else | |
106 | runp = runp->next; | |
107 | ||
108 | if (runp != NULL) | |
109 | { | |
110 | struct thread_start_data *td = malloc (sizeof (*td)); | |
111 | ||
112 | /* There is not much we can do if the allocation fails. */ | |
113 | if (td != NULL) | |
114 | { | |
115 | /* This is the signal we are waiting for. */ | |
116 | td->thrfunc = tk->thrfunc; | |
117 | td->sival = tk->sival; | |
118 | ||
119 | pthread_t th; | |
120 | (void) pthread_create (&th, &tk->attr, | |
121 | timer_sigev_thread, td); | |
122 | } | |
a6375d11 | 123 | } |
f160a450 UD |
124 | |
125 | pthread_mutex_unlock (&__active_timer_sigev_thread_lock); | |
e7608d77 UD |
126 | } |
127 | else if (si.si_code == SI_TKILL) | |
128 | /* The thread is canceled. */ | |
129 | pthread_exit (NULL); | |
09402f5b UD |
130 | } |
131 | } | |
132 | } | |
133 | ||
5f5004df UD |
134 | |
135 | /* Control variable for helper thread creation. */ | |
136 | pthread_once_t __helper_once attribute_hidden; | |
137 | ||
138 | ||
139 | /* TID of the helper thread. */ | |
140 | pid_t __helper_tid attribute_hidden; | |
141 | ||
142 | ||
143 | /* Reset variables so that after a fork a new helper thread gets started. */ | |
144 | static void | |
145 | reset_helper_control (void) | |
146 | { | |
147 | __helper_once = PTHREAD_ONCE_INIT; | |
148 | __helper_tid = 0; | |
149 | } | |
150 | ||
151 | ||
152 | void | |
153 | attribute_hidden | |
154 | __start_helper_thread (void) | |
155 | { | |
156 | /* The helper thread needs only very little resources | |
157 | and should go away automatically when canceled. */ | |
158 | pthread_attr_t attr; | |
159 | (void) pthread_attr_init (&attr); | |
2c1094bd | 160 | (void) pthread_attr_setstacksize (&attr, __pthread_get_minstack (&attr)); |
5f5004df | 161 | |
fd4af664 UD |
162 | /* Block all signals in the helper thread but SIGSETXID. To do this |
163 | thoroughly we temporarily have to block all signals here. The | |
164 | helper can lose wakeups if SIGCANCEL is not blocked throughout, | |
8558d715 UD |
165 | but sigfillset omits it SIGSETXID. So, we add SIGCANCEL back |
166 | explicitly here. */ | |
fa0e226b UD |
167 | sigset_t ss; |
168 | sigset_t oss; | |
169 | sigfillset (&ss); | |
0086214c | 170 | __sigaddset (&ss, SIGCANCEL); |
fa0e226b UD |
171 | INTERNAL_SYSCALL_DECL (err); |
172 | INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &ss, &oss, _NSIG / 8); | |
173 | ||
5f5004df UD |
174 | /* Create the helper thread for this timer. */ |
175 | pthread_t th; | |
176 | int res = pthread_create (&th, &attr, timer_helper_thread, NULL); | |
177 | if (res == 0) | |
178 | /* We managed to start the helper thread. */ | |
179 | __helper_tid = ((struct pthread *) th)->tid; | |
180 | ||
fa0e226b UD |
181 | /* Restore the signal mask. */ |
182 | INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &oss, NULL, | |
183 | _NSIG / 8); | |
184 | ||
5f5004df UD |
185 | /* No need for the attribute anymore. */ |
186 | (void) pthread_attr_destroy (&attr); | |
187 | ||
188 | /* We have to make sure that after fork()ing a new helper thread can | |
189 | be created. */ | |
190 | pthread_atfork (NULL, NULL, reset_helper_control); | |
191 | } |