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glibc/sysdeps/nptl/gai_misc.h
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/* Copyright (C) 2006-2014 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 | |
<http://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 <pthreadP.h> | |
#include <lowlevellock.h> | |
#define DONT_NEED_GAI_MISC_COND 1 | |
#define GAI_MISC_NOTIFY(waitlist) \ | |
do { \ | |
if (*waitlist->counterp > 0 && --*waitlist->counterp == 0) \ | |
lll_futex_wake (waitlist->counterp, 1, LLL_PRIVATE); \ | |
} while (0) | |
#define GAI_MISC_WAIT(result, futex, timeout, cancel) \ | |
do { \ | |
volatile int *futexaddr = &futex; \ | |
int oldval = futex; \ | |
\ | |
if (oldval != 0) \ | |
{ \ | |
pthread_mutex_unlock (&__gai_requests_mutex); \ | |
\ | |
int oldtype; \ | |
if (cancel) \ | |
oldtype = LIBC_CANCEL_ASYNC (); \ | |
\ | |
int status; \ | |
do \ | |
{ \ | |
status = lll_futex_timed_wait (futexaddr, oldval, timeout, \ | |
LLL_PRIVATE); \ | |
if (status != -EWOULDBLOCK) \ | |
break; \ | |
\ | |
oldval = *futexaddr; \ | |
} \ | |
while (oldval != 0); \ | |
\ | |
if (cancel) \ | |
LIBC_CANCEL_RESET (oldtype); \ | |
\ | |
if (status == -EINTR) \ | |
result = EINTR; \ | |
else if (status == -ETIMEDOUT) \ | |
result = EAGAIN; \ | |
else \ | |
assert (status == 0 || status == -EWOULDBLOCK); \ | |
\ | |
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); | |
INTERNAL_SYSCALL_DECL (err); | |
INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &ss, NULL, _NSIG / 8); | |
} | |
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); | |
INTERNAL_SYSCALL_DECL (err); | |
INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &ss, &oss, _NSIG / 8); | |
int ret = pthread_create (threadp, &attr, tf, arg); | |
/* Restore the signal mask. */ | |
INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &oss, NULL, | |
_NSIG / 8); | |
(void) pthread_attr_destroy (&attr); | |
return ret; | |
} | |
#include_next <gai_misc.h> |