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/* Copyright (C) 2006-2020 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* We define a special synchronization primitive for AIO. POSIX
conditional variables would be ideal but the pthread_cond_*wait
operations do not return on EINTR. This is a requirement for
correct aio_suspend and lio_listio implementations. */
#include <assert.h>
#include <signal.h>
#include <nptl/pthreadP.h>
#include <futex-internal.h>
#define DONT_NEED_GAI_MISC_COND 1
#define GAI_MISC_NOTIFY(waitlist) \
do { \
if (*waitlist->counterp > 0 && --*waitlist->counterp == 0) \
futex_wake ((unsigned int *) waitlist->counterp, 1, FUTEX_PRIVATE); \
} while (0)
#define GAI_MISC_WAIT(result, futex, timeout, cancel) \
do { \
volatile unsigned int *futexaddr = &futex; \
unsigned int oldval = futex; \
\
if (oldval != 0) \
{ \
pthread_mutex_unlock (&__gai_requests_mutex); \
\
int status; \
do \
{ \
if (cancel) \
status = futex_reltimed_wait_cancelable ( \
(unsigned int *) futexaddr, oldval, timeout, FUTEX_PRIVATE); \
else \
status = futex_reltimed_wait ((unsigned int *) futexaddr, \
oldval, timeout, FUTEX_PRIVATE); \
if (status != EAGAIN) \
break; \
\
oldval = *futexaddr; \
} \
while (oldval != 0); \
\
if (status == EINTR) \
result = EINTR; \
else if (status == ETIMEDOUT) \
result = EAGAIN; \
else \
assert (status == 0 || status == EAGAIN); \
\
pthread_mutex_lock (&__gai_requests_mutex); \
} \
} while (0)
#define gai_start_notify_thread __gai_start_notify_thread
#define gai_create_helper_thread __gai_create_helper_thread
extern inline void
__gai_start_notify_thread (void)
{
sigset_t ss;
sigemptyset (&ss);
int sigerr __attribute__ ((unused));
sigerr = pthread_sigmask (SIG_SETMASK, &ss, NULL);
assert_perror (sigerr);
}
extern inline int
__gai_create_helper_thread (pthread_t *threadp, void *(*tf) (void *),
void *arg)
{
pthread_attr_t attr;
/* Make sure the thread is created detached. */
pthread_attr_init (&attr);
pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
/* The helper thread needs only very little resources. */
(void) pthread_attr_setstacksize (&attr,
__pthread_get_minstack (&attr)
+ 4 * PTHREAD_STACK_MIN);
/* Block all signals in the helper thread. To do this thoroughly we
temporarily have to block all signals here. */
sigset_t ss;
sigset_t oss;
sigfillset (&ss);
int sigerr __attribute__ ((unused));
sigerr = pthread_sigmask (SIG_SETMASK, &ss, &oss);
assert_perror (sigerr);
int ret = pthread_create (threadp, &attr, tf, arg);
/* Restore the signal mask. */
sigerr = pthread_sigmask (SIG_SETMASK, &oss, NULL);
assert_perror (sigerr);
(void) pthread_attr_destroy (&attr);
return ret;
}
#include_next <gai_misc.h>
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