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2b778ceb | 1 | /* Copyright (C) 2003-2021 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 | 16 | License along with the GNU C Library; see the file COPYING.LIB. If |
5a82c748 | 17 | not, see <https://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> |
3c79234c | 24 | #include <pthreadP.h> |
09402f5b UD |
25 | #include "kernel-posix-timers.h" |
26 | ||
27 | ||
f160a450 | 28 | /* List of active SIGEV_THREAD timers. */ |
30639e79 | 29 | struct timer *__timer_active_sigev_thread; |
f160a450 | 30 | |
2c16cb88 | 31 | /* Lock for _timer_active_sigev_thread. */ |
30639e79 | 32 | pthread_mutex_t __timer_active_sigev_thread_lock = PTHREAD_MUTEX_INITIALIZER; |
f160a450 | 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 | { | |
27d83441 | 45 | __libc_signal_unblock_sigtimer (NULL); |
fa0e226b | 46 | |
a6375d11 | 47 | struct thread_start_data *td = (struct thread_start_data *) arg; |
a6375d11 UD |
48 | void (*thrfunc) (sigval_t) = td->thrfunc; |
49 | sigval_t sival = td->sival; | |
50 | ||
51 | /* The TD object was allocated in timer_helper_thread. */ | |
52 | free (td); | |
09402f5b UD |
53 | |
54 | /* Call the user-provided function. */ | |
a6375d11 | 55 | thrfunc (sival); |
09402f5b UD |
56 | |
57 | return NULL; | |
58 | } | |
59 | ||
60 | ||
61 | /* Helper function to support starting threads for SIGEV_THREAD. */ | |
2c16cb88 | 62 | static _Noreturn void * |
5f5004df | 63 | timer_helper_thread (void *arg) |
09402f5b | 64 | { |
09402f5b UD |
65 | /* Endless loop of waiting for signals. The loop is only ended when |
66 | the thread is canceled. */ | |
67 | while (1) | |
68 | { | |
69 | siginfo_t si; | |
70 | ||
2c16cb88 | 71 | while (__sigwaitinfo (&sigtimer_set, &si) < 0); |
27d83441 | 72 | if (si.si_code == SI_TIMER) |
09402f5b | 73 | { |
27d83441 AZ |
74 | struct timer *tk = (struct timer *) si.si_ptr; |
75 | ||
76 | /* Check the timer is still used and will not go away | |
77 | while we are reading the values here. */ | |
2c16cb88 | 78 | __pthread_mutex_lock (&__timer_active_sigev_thread_lock); |
a6375d11 | 79 | |
2c16cb88 | 80 | struct timer *runp = __timer_active_sigev_thread; |
27d83441 AZ |
81 | while (runp != NULL) |
82 | if (runp == tk) | |
83 | break; | |
84 | else | |
85 | runp = runp->next; | |
a6375d11 | 86 | |
27d83441 AZ |
87 | if (runp != NULL) |
88 | { | |
89 | struct thread_start_data *td = malloc (sizeof (*td)); | |
f160a450 | 90 | |
27d83441 AZ |
91 | /* There is not much we can do if the allocation fails. */ |
92 | if (td != NULL) | |
f160a450 | 93 | { |
27d83441 AZ |
94 | /* This is the signal we are waiting for. */ |
95 | td->thrfunc = tk->thrfunc; | |
96 | td->sival = tk->sival; | |
f160a450 | 97 | |
27d83441 | 98 | pthread_t th; |
2c16cb88 | 99 | __pthread_create (&th, &tk->attr, timer_sigev_thread, td); |
27d83441 | 100 | } |
e7608d77 | 101 | } |
27d83441 | 102 | |
2c16cb88 | 103 | __pthread_mutex_unlock (&__timer_active_sigev_thread_lock); |
09402f5b UD |
104 | } |
105 | } | |
106 | } | |
107 | ||
5f5004df UD |
108 | |
109 | /* Control variable for helper thread creation. */ | |
7c241325 | 110 | pthread_once_t __timer_helper_once = PTHREAD_ONCE_INIT; |
5f5004df UD |
111 | |
112 | ||
113 | /* TID of the helper thread. */ | |
7c241325 | 114 | pid_t __timer_helper_tid; |
5f5004df UD |
115 | |
116 | ||
117 | /* Reset variables so that after a fork a new helper thread gets started. */ | |
2c16cb88 FW |
118 | void |
119 | __timer_fork_subprocess (void) | |
5f5004df | 120 | { |
2c16cb88 FW |
121 | __timer_helper_once = PTHREAD_ONCE_INIT; |
122 | __timer_helper_tid = 0; | |
5f5004df UD |
123 | } |
124 | ||
125 | ||
126 | void | |
2c16cb88 | 127 | __timer_start_helper_thread (void) |
5f5004df UD |
128 | { |
129 | /* The helper thread needs only very little resources | |
130 | and should go away automatically when canceled. */ | |
131 | pthread_attr_t attr; | |
2c16cb88 FW |
132 | __pthread_attr_init (&attr); |
133 | __pthread_attr_setstacksize (&attr, __pthread_get_minstack (&attr)); | |
5f5004df | 134 | |
ba9f6ee9 | 135 | /* Block all signals in the helper thread but SIGSETXID. */ |
fa0e226b | 136 | sigset_t ss; |
ba9f6ee9 FW |
137 | __sigfillset (&ss); |
138 | __sigdelset (&ss, SIGSETXID); | |
139 | int res = __pthread_attr_setsigmask_internal (&attr, &ss); | |
140 | if (res != 0) | |
141 | { | |
2c16cb88 | 142 | __pthread_attr_destroy (&attr); |
ba9f6ee9 FW |
143 | return; |
144 | } | |
fa0e226b | 145 | |
5f5004df UD |
146 | /* Create the helper thread for this timer. */ |
147 | pthread_t th; | |
2c16cb88 | 148 | res = __pthread_create (&th, &attr, timer_helper_thread, NULL); |
5f5004df UD |
149 | if (res == 0) |
150 | /* We managed to start the helper thread. */ | |
2c16cb88 | 151 | __timer_helper_tid = ((struct pthread *) th)->tid; |
5f5004df UD |
152 | |
153 | /* No need for the attribute anymore. */ | |
2c16cb88 | 154 | __pthread_attr_destroy (&attr); |
5f5004df | 155 | } |