96 lines
2.7 KiB
C
96 lines
2.7 KiB
C
/* Copyright (C) 2002-2018 Free Software Foundation, Inc.
|
|
Contributed by Zack Weinberg <zack@codesourcery.com>
|
|
|
|
This file is part of GCC.
|
|
|
|
GCC is free software; you can redistribute it and/or modify it under
|
|
the terms of the GNU General Public License as published by the Free
|
|
Software Foundation; either version 3, or (at your option) any later
|
|
version.
|
|
|
|
GCC 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 General Public License
|
|
for more details.
|
|
|
|
Under Section 7 of GPL version 3, you are granted additional
|
|
permissions described in the GCC Runtime Library Exception, version
|
|
3.1, as published by the Free Software Foundation.
|
|
|
|
You should have received a copy of the GNU General Public License and
|
|
a copy of the GCC Runtime Library Exception along with this program;
|
|
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
/* Threads compatibility routines for libgcc2 for VxWorks.
|
|
These are out-of-line routines called from gthr-vxworks.h. */
|
|
|
|
#include "tconfig.h"
|
|
#include "tsystem.h"
|
|
#include "gthr.h"
|
|
|
|
#if defined(__GTHREADS)
|
|
#include <vxWorks.h>
|
|
#ifndef __RTP__
|
|
#include <vxLib.h>
|
|
#endif
|
|
#include <taskLib.h>
|
|
#ifndef __RTP__
|
|
#include <taskHookLib.h>
|
|
#else
|
|
# include <errno.h>
|
|
#endif
|
|
|
|
/* Init-once operation.
|
|
|
|
This would be a clone of the implementation from gthr-solaris.h,
|
|
except that we have a bootstrap problem - the whole point of this
|
|
exercise is to prevent double initialization, but if two threads
|
|
are racing with each other, once->mutex is liable to be initialized
|
|
by both. Then each thread will lock its own mutex, and proceed to
|
|
call the initialization routine.
|
|
|
|
So instead we use a bare atomic primitive (vxTas()) to handle
|
|
mutual exclusion. Threads losing the race then busy-wait, calling
|
|
taskDelay() to yield the processor, until the initialization is
|
|
completed. Inefficient, but reliable. */
|
|
|
|
int
|
|
__gthread_once (__gthread_once_t *guard, void (*func)(void))
|
|
{
|
|
if (guard->done)
|
|
return 0;
|
|
|
|
#ifdef __RTP__
|
|
__gthread_lock_library ();
|
|
#else
|
|
while (!vxTas ((void *)&guard->busy))
|
|
{
|
|
#ifdef __PPC__
|
|
/* This can happen on powerpc, which is using all 32 bits
|
|
of the gthread_once_t structure. */
|
|
if (guard->done)
|
|
return 0;
|
|
#endif
|
|
taskDelay (1);
|
|
}
|
|
#endif
|
|
|
|
/* Only one thread at a time gets here. Check ->done again, then
|
|
go ahead and call func() if no one has done it yet. */
|
|
if (!guard->done)
|
|
{
|
|
func ();
|
|
guard->done = 1;
|
|
}
|
|
|
|
#ifdef __RTP__
|
|
__gthread_unlock_library ();
|
|
#else
|
|
guard->busy = 0;
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
#endif /* __GTHREADS */
|