blob: 78b677647a3e42ca01258f8ab079a65cb5c68831 [file] [log] [blame]
/* Copyright (C) 2002-2019 Free Software Foundation, Inc.
Contributed by Zack Weinberg <>
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
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
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
<>. */
/* 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>
#include <taskLib.h>
#ifndef __RTP__
#include <taskHookLib.h>
# include <errno.h>
/* 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. */
__gthread_once (__gthread_once_t *guard, void (*func)(void))
if (guard->done)
return 0;
#ifdef __RTP__
__gthread_lock_library ();
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;
taskDelay (1);
/* 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 ();
guard->busy = 0;
return 0;
#endif /* __GTHREADS */