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/* Lock a mutex with a timeout. Generic version.
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Copyright (C) 2000-2018 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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#include <pthread.h>
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#include <assert.h>
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#include <pt-internal.h>
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#define LOSE do { * (int *) 0 = 0; } while (1)
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/* Try to lock MUTEX, block until *ABSTIME if it is already held. As
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a GNU extension, if TIMESPEC is NULL then wait forever. */
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int
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__pthread_mutex_timedlock_internal (struct __pthread_mutex *mutex,
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const struct timespec *abstime)
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{
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error_t err;
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int drain;
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struct __pthread *self;
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const struct __pthread_mutexattr *attr = mutex->__attr;
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if (attr == __PTHREAD_ERRORCHECK_MUTEXATTR)
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attr = &__pthread_errorcheck_mutexattr;
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if (attr == __PTHREAD_RECURSIVE_MUTEXATTR)
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attr = &__pthread_recursive_mutexattr;
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__pthread_spin_lock (&mutex->__lock);
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if (__pthread_spin_trylock (&mutex->__held) == 0)
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/* Successfully acquired the lock. */
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{
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#ifdef ALWAYS_TRACK_MUTEX_OWNER
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# ifndef NDEBUG
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self = _pthread_self ();
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if (self != NULL)
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/* The main thread may take a lock before the library is fully
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initialized, in particular, before the main thread has a
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TCB. */
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{
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assert (mutex->__owner == NULL);
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mutex->__owner = _pthread_self ();
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}
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# endif
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#endif
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if (attr != NULL)
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switch (attr->__mutex_type)
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{
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case PTHREAD_MUTEX_NORMAL:
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break;
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case PTHREAD_MUTEX_RECURSIVE:
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mutex->__locks = 1;
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case PTHREAD_MUTEX_ERRORCHECK:
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mutex->__owner = _pthread_self ();
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break;
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default:
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LOSE;
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}
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__pthread_spin_unlock (&mutex->__lock);
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return 0;
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}
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/* The lock is busy. */
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self = _pthread_self ();
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assert (self);
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if (attr == NULL || attr->__mutex_type == PTHREAD_MUTEX_NORMAL)
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{
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#if defined(ALWAYS_TRACK_MUTEX_OWNER)
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assert (mutex->__owner != self);
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#endif
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}
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else
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{
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switch (attr->__mutex_type)
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{
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case PTHREAD_MUTEX_ERRORCHECK:
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if (mutex->__owner == self)
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{
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__pthread_spin_unlock (&mutex->__lock);
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return EDEADLK;
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}
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break;
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case PTHREAD_MUTEX_RECURSIVE:
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if (mutex->__owner == self)
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{
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mutex->__locks++;
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__pthread_spin_unlock (&mutex->__lock);
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return 0;
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}
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break;
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default:
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LOSE;
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}
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}
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#if !defined(ALWAYS_TRACK_MUTEX_OWNER)
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if (attr != NULL && attr->__mutex_type != PTHREAD_MUTEX_NORMAL)
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#endif
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assert (mutex->__owner);
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if (abstime != NULL && (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000))
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return EINVAL;
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/* Add ourselves to the queue. */
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__pthread_enqueue (&mutex->__queue, self);
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__pthread_spin_unlock (&mutex->__lock);
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/* Block the thread. */
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if (abstime != NULL)
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err = __pthread_timedblock (self, abstime, CLOCK_REALTIME);
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else
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{
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err = 0;
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__pthread_block (self);
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}
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__pthread_spin_lock (&mutex->__lock);
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if (self->prevp == NULL)
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/* Another thread removed us from the queue, which means a wakeup message
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has been sent. It was either consumed while we were blocking, or
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queued after we timed out and before we acquired the mutex lock, in
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which case the message queue must be drained. */
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drain = err ? 1 : 0;
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else
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{
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/* We're still in the queue. Noone attempted to wake us up, i.e. we
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timed out. */
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__pthread_dequeue (self);
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drain = 0;
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}
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__pthread_spin_unlock (&mutex->__lock);
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if (drain)
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__pthread_block (self);
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if (err)
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{
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assert (err == ETIMEDOUT);
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return err;
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}
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#if !defined(ALWAYS_TRACK_MUTEX_OWNER)
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if (attr != NULL && attr->__mutex_type != PTHREAD_MUTEX_NORMAL)
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#endif
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{
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assert (mutex->__owner == self);
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}
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if (attr != NULL)
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switch (attr->__mutex_type)
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{
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case PTHREAD_MUTEX_NORMAL:
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break;
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case PTHREAD_MUTEX_RECURSIVE:
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assert (mutex->__locks == 0);
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mutex->__locks = 1;
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case PTHREAD_MUTEX_ERRORCHECK:
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mutex->__owner = self;
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break;
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default:
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LOSE;
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}
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return 0;
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}
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int
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pthread_mutex_timedlock (struct __pthread_mutex *mutex,
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const struct timespec *abstime)
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{
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return __pthread_mutex_timedlock_internal (mutex, abstime);
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}
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