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glibc/nptl/pthread_barrier_wait.c
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/* Copyright (C) 2003-2015 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, see | |
<http://www.gnu.org/licenses/>. */ | |
#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, ibarrier->private ^ FUTEX_PRIVATE_FLAG); | |
/* 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, | |
ibarrier->private ^ FUTEX_PRIVATE_FLAG); | |
/* 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; | |
/* Before suspending, make the barrier available to others. */ | |
lll_unlock (ibarrier->lock, ibarrier->private ^ FUTEX_PRIVATE_FLAG); | |
/* Wait for the event counter of the barrier to change. */ | |
do | |
lll_futex_wait (&ibarrier->curr_event, event, | |
ibarrier->private ^ FUTEX_PRIVATE_FLAG); | |
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_increment_val (&ibarrier->left) == init_count) | |
/* We are done. */ | |
lll_unlock (ibarrier->lock, ibarrier->private ^ FUTEX_PRIVATE_FLAG); | |
return result; | |
} | |
weak_alias (__pthread_barrier_wait, pthread_barrier_wait) |