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a88c926368
2003-02-05 Ulrich Drepper <drepper@redhat.com> * sysdeps/pthread/bits/libc-lock.h (__libc_once): Set control variable for non-libpthread case to the same value the pthread_once function would use.
127 lines
3.8 KiB
C
127 lines
3.8 KiB
C
/* Copyright (C) 2003 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Martin Schwidefsky <schwidefsky@de.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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <endian.h>
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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 <pthread.h>
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#include <pthreadP.h>
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#include <shlib-compat.h>
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void
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__attribute__ ((visibility ("hidden")))
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__condvar_cleanup (void *arg)
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{
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pthread_cond_t *cond = (pthread_cond_t *) arg;
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/* We are going to modify shared data. */
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lll_mutex_lock (cond->__data.__lock);
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/* This thread is not waiting anymore. Adjust the sequence counters
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appropriately. */
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++cond->__data.__wakeup_seq;
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++cond->__data.__woken_seq;
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/* We are done. */
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lll_mutex_unlock (cond->__data.__lock);
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}
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int
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__pthread_cond_wait (cond, mutex)
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pthread_cond_t *cond;
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pthread_mutex_t *mutex;
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{
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struct _pthread_cleanup_buffer buffer;
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/* Make sure we are along. */
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lll_mutex_lock (cond->__data.__lock);
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/* Now we can release the mutex. */
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__pthread_mutex_unlock_internal (mutex);
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/* We have one new user of the condvar. */
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++cond->__data.__total_seq;
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/* Before we block we enable cancellation. Therefore we have to
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install a cancellation handler. */
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__pthread_cleanup_push (&buffer, __condvar_cleanup, cond);
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/* The current values of the wakeup counter. The "woken" counter
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must exceed this value. */
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unsigned long long int val;
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unsigned long long int seq;
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val = seq = cond->__data.__wakeup_seq;
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/* The futex syscall operates on a 32-bit word. That is fine, we
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just use the low 32 bits of the sequence counter. */
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#if BYTE_ORDER == LITTLE_ENDIAN
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int *futex = ((int *) (&cond->__data.__wakeup_seq));
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#elif BYTE_ORDER == BIG_ENDIAN
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int *futex = ((int *) (&cond->__data.__wakeup_seq)) + 1;
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#else
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# error "No valid byte order"
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#endif
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while (1)
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{
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/* Prepare to wait. Release the condvar futex. */
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lll_mutex_unlock (cond->__data.__lock);
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/* Enable asynchronous cancellation. Required by the standard. */
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int oldtype = __pthread_enable_asynccancel ();
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/* Wait until woken by signal or broadcast. Note that we
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truncate the 'val' value to 32 bits. */
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lll_futex_wait (futex, (unsigned int) val);
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/* Disable asynchronous cancellation. */
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__pthread_disable_asynccancel (oldtype);
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/* We are going to look at shared data again, so get the lock. */
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lll_mutex_lock(cond->__data.__lock);
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/* Check whether we are eligible for wakeup. */
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val = cond->__data.__wakeup_seq;
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if (cond->__data.__woken_seq >= seq
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&& cond->__data.__woken_seq < val)
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break;
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}
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/* Another thread woken up. */
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++cond->__data.__woken_seq;
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/* We are done with the condvar. */
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lll_mutex_unlock (cond->__data.__lock);
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/* The cancellation handling is back to normal, remove the handler. */
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__pthread_cleanup_pop (&buffer, 0);
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/* Get the mutex before returning. */
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__pthread_mutex_lock_internal (mutex);
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return 0;
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}
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versioned_symbol (libpthread, __pthread_cond_wait, pthread_cond_wait,
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GLIBC_2_3_2);
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