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118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
/* sem_timedwait -- wait on a semaphore. Generic futex-using version.
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Copyright (C) 2003-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
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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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#include <errno.h>
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#include <sysdep.h>
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#include <lowlevellock.h>
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#include <internaltypes.h>
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#include <semaphore.h>
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#include <sys/time.h>
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#include <pthreadP.h>
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#include <shlib-compat.h>
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extern void __sem_wait_cleanup (void *arg) attribute_hidden;
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/* This is in a seperate function in order to make sure gcc
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puts the call site into an exception region, and thus the
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cleanups get properly run. */
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static int
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__attribute__ ((noinline))
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do_futex_timed_wait (struct new_sem *isem, struct timespec *rt)
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{
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int err, oldtype = __pthread_enable_asynccancel ();
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err = lll_futex_timed_wait (&isem->value, 0, rt,
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isem->private ^ FUTEX_PRIVATE_FLAG);
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__pthread_disable_asynccancel (oldtype);
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return err;
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}
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int
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sem_timedwait (sem_t *sem, const struct timespec *abstime)
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{
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struct new_sem *isem = (struct new_sem *) sem;
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int err;
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if (atomic_decrement_if_positive (&isem->value) > 0)
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return 0;
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if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
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{
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__set_errno (EINVAL);
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return -1;
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}
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atomic_increment (&isem->nwaiters);
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pthread_cleanup_push (__sem_wait_cleanup, isem);
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while (1)
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{
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struct timeval tv;
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struct timespec rt;
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int sec, nsec;
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/* Get the current time. */
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__gettimeofday (&tv, NULL);
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/* Compute relative timeout. */
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sec = abstime->tv_sec - tv.tv_sec;
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nsec = abstime->tv_nsec - tv.tv_usec * 1000;
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if (nsec < 0)
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{
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nsec += 1000000000;
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--sec;
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}
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/* Already timed out? */
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if (sec < 0)
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{
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__set_errno (ETIMEDOUT);
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err = -1;
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break;
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}
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/* Do wait. */
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rt.tv_sec = sec;
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rt.tv_nsec = nsec;
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err = do_futex_timed_wait(isem, &rt);
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if (err != 0 && err != -EWOULDBLOCK)
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{
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__set_errno (-err);
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err = -1;
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break;
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}
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if (atomic_decrement_if_positive (&isem->value) > 0)
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{
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err = 0;
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break;
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}
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}
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pthread_cleanup_pop (0);
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atomic_decrement (&isem->nwaiters);
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return err;
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}
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