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/* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <pthreadP.h>
/* Wait on barrier. */
int
pthread_barrier_wait (barrier)
pthread_barrier_t *barrier;
{
struct pthread_barrier *ibarrier = (struct pthread_barrier *) barrier;
int result = 0;
/* Make sure we are alone. */
lll_lock (ibarrier->lock);
/* One more arrival. */
--ibarrier->left;
/* Are these all? */
if (ibarrier->left == 0)
{
/* Yes. Increment the event counter to avoid invalid wake-ups and
tell the current waiters that it is their turn. */
++ibarrier->curr_event;
/* Wake up everybody. */
lll_futex_wake (&ibarrier->curr_event, INT_MAX);
/* This is the thread which finished the serialization. */
result = PTHREAD_BARRIER_SERIAL_THREAD;
}
else
{
/* The number of the event we are waiting for. The barrier's event
number must be bumped before we continue. */
unsigned int event = ibarrier->curr_event;
do
{
/* Before suspending, make the barrier available to others. */
lll_unlock (ibarrier->lock);
/* Wait for the event counter of the barrier to change. */
lll_futex_wait (&ibarrier->curr_event, event);
/* We are going to access shared data. */
lll_lock (ibarrier->lock);
}
while (event == ibarrier->curr_event);
}
/* Make sure the init_count is stored locally or in a register. */
unsigned int init_count = ibarrier->init_count;
/* If this was the last woken thread, unlock. */
if (atomic_exchange_and_add (&ibarrier->left, 1) == init_count - 1)
/* We are done. */
lll_unlock (ibarrier->lock);
return result;
}
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