/* Copyright (C) 2003, 2004, 2007 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, 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; }