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128 lines
4.0 KiB
C
128 lines
4.0 KiB
C
/* Copyright (C) 2006-2018 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
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License as published by the Free Software Foundation; either
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version 2.1 of the 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; if not, see
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<http://www.gnu.org/licenses/>. */
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/* We define a special synchronization primitive for AIO. POSIX
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conditional variables would be ideal but the pthread_cond_*wait
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operations do not return on EINTR. This is a requirement for
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correct aio_suspend and lio_listio implementations. */
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#include <assert.h>
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#include <signal.h>
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#include <nptl/pthreadP.h>
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#include <futex-internal.h>
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#define DONT_NEED_GAI_MISC_COND 1
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#define GAI_MISC_NOTIFY(waitlist) \
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do { \
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if (*waitlist->counterp > 0 && --*waitlist->counterp == 0) \
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futex_wake ((unsigned int *) waitlist->counterp, 1, FUTEX_PRIVATE); \
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} while (0)
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#define GAI_MISC_WAIT(result, futex, timeout, cancel) \
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do { \
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volatile unsigned int *futexaddr = &futex; \
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unsigned int oldval = futex; \
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\
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if (oldval != 0) \
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{ \
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pthread_mutex_unlock (&__gai_requests_mutex); \
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\
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int oldtype; \
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if (cancel) \
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oldtype = LIBC_CANCEL_ASYNC (); \
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\
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int status; \
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do \
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{ \
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status = futex_reltimed_wait ((unsigned int *) futexaddr, oldval, \
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timeout, FUTEX_PRIVATE); \
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if (status != EAGAIN) \
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break; \
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\
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oldval = *futexaddr; \
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} \
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while (oldval != 0); \
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\
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if (cancel) \
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LIBC_CANCEL_RESET (oldtype); \
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\
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if (status == EINTR) \
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result = EINTR; \
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else if (status == ETIMEDOUT) \
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result = EAGAIN; \
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else \
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assert (status == 0 || status == EAGAIN); \
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\
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pthread_mutex_lock (&__gai_requests_mutex); \
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} \
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} while (0)
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#define gai_start_notify_thread __gai_start_notify_thread
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/* For some reason, with clang this define causes a linktime failure
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building libanl.so. */
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#ifndef __clang__
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#define gai_create_helper_thread __gai_create_helper_thread
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#endif
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extern inline void
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__gai_start_notify_thread (void)
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{
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sigset_t ss;
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sigemptyset (&ss);
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int sigerr __attribute__ ((unused));
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sigerr = pthread_sigmask (SIG_SETMASK, &ss, NULL);
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assert_perror (sigerr);
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}
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extern inline int
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__gai_create_helper_thread (pthread_t *threadp, void *(*tf) (void *),
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void *arg)
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{
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pthread_attr_t attr;
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/* Make sure the thread is created detached. */
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pthread_attr_init (&attr);
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pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
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/* The helper thread needs only very little resources. */
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(void) pthread_attr_setstacksize (&attr,
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__pthread_get_minstack (&attr)
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+ 4 * PTHREAD_STACK_MIN);
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/* Block all signals in the helper thread. To do this thoroughly we
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temporarily have to block all signals here. */
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sigset_t ss;
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sigset_t oss;
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sigfillset (&ss);
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int sigerr __attribute__ ((unused));
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sigerr = pthread_sigmask (SIG_SETMASK, &ss, &oss);
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assert_perror (sigerr);
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int ret = pthread_create (threadp, &attr, tf, arg);
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/* Restore the signal mask. */
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sigerr = pthread_sigmask (SIG_SETMASK, &oss, NULL);
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assert_perror (sigerr);
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(void) pthread_attr_destroy (&attr);
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return ret;
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}
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#include_next <gai_misc.h>
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