155 lines
4.0 KiB
C
155 lines
4.0 KiB
C
/* Copyright (C) 2003-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <setjmp.h>
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#include <signal.h>
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#include <stdbool.h>
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#include <sysdep-cancel.h>
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#include <pthreadP.h>
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#include "kernel-posix-timers.h"
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/* List of active SIGEV_THREAD timers. */
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struct timer *__timer_active_sigev_thread;
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/* Lock for _timer_active_sigev_thread. */
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pthread_mutex_t __timer_active_sigev_thread_lock = PTHREAD_MUTEX_INITIALIZER;
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struct thread_start_data
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{
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void (*thrfunc) (sigval_t);
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sigval_t sival;
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};
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/* Helper thread to call the user-provided function. */
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static void *
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timer_sigev_thread (void *arg)
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{
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signal_unblock_sigtimer ();
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struct thread_start_data *td = (struct thread_start_data *) arg;
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void (*thrfunc) (sigval_t) = td->thrfunc;
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sigval_t sival = td->sival;
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/* The TD object was allocated in timer_helper_thread. */
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free (td);
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/* Call the user-provided function. */
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thrfunc (sival);
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return NULL;
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}
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/* Helper function to support starting threads for SIGEV_THREAD. */
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static _Noreturn void *
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timer_helper_thread (void *arg)
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{
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/* Endless loop of waiting for signals. The loop is only ended when
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the thread is canceled. */
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while (1)
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{
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siginfo_t si;
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while (__sigwaitinfo (&sigtimer_set, &si) < 0);
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if (si.si_code == SI_TIMER)
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{
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struct timer *tk = (struct timer *) si.si_ptr;
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/* Check the timer is still used and will not go away
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while we are reading the values here. */
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__pthread_mutex_lock (&__timer_active_sigev_thread_lock);
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struct timer *runp = __timer_active_sigev_thread;
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while (runp != NULL)
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if (runp == tk)
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break;
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else
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runp = runp->next;
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if (runp != NULL)
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{
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struct thread_start_data *td = malloc (sizeof (*td));
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/* There is not much we can do if the allocation fails. */
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if (td != NULL)
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{
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/* This is the signal we are waiting for. */
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td->thrfunc = tk->thrfunc;
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td->sival = tk->sival;
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pthread_t th;
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__pthread_create (&th, &tk->attr, timer_sigev_thread, td);
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}
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}
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__pthread_mutex_unlock (&__timer_active_sigev_thread_lock);
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}
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}
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}
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/* Control variable for helper thread creation. */
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pthread_once_t __timer_helper_once = PTHREAD_ONCE_INIT;
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/* TID of the helper thread. */
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pid_t __timer_helper_tid;
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/* Reset variables so that after a fork a new helper thread gets started. */
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void
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__timer_fork_subprocess (void)
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{
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__timer_helper_once = PTHREAD_ONCE_INIT;
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__timer_helper_tid = 0;
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}
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void
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__timer_start_helper_thread (void)
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{
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/* The helper thread needs only very little resources
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and should go away automatically when canceled. */
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pthread_attr_t attr;
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__pthread_attr_init (&attr);
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__pthread_attr_setstacksize (&attr, __pthread_get_minstack (&attr));
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/* Block all signals in the helper thread but SIGSETXID. */
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sigset_t ss;
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__sigfillset (&ss);
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__sigdelset (&ss, SIGSETXID);
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int res = __pthread_attr_setsigmask_internal (&attr, &ss);
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if (res != 0)
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{
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__pthread_attr_destroy (&attr);
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return;
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}
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/* Create the helper thread for this timer. */
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pthread_t th;
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res = __pthread_create (&th, &attr, timer_helper_thread, NULL);
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if (res == 0)
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/* We managed to start the helper thread. */
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__timer_helper_tid = ((struct pthread *) th)->tid;
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/* No need for the attribute anymore. */
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__pthread_attr_destroy (&attr);
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}
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