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/* Copyright (C) 2008-2021 Free Software Foundation, Inc.
Contributed by Richard Henderson <rth@redhat.com>.
This file is part of the GNU Transactional Memory Library (libitm).
Libitm 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 of the License, or
(at your option) any later version.
Libitm 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/>. */
/* Provide access to the futex system call. */
#include "libitm_i.h"
#include "futex.h"
#include <futex_bits.h>
#include <errno.h>
namespace GTM HIDDEN {
#define FUTEX_WAIT 0
#define FUTEX_WAKE 1
#define FUTEX_PRIVATE_FLAG 128
static int gtm_futex_wait = FUTEX_WAIT | FUTEX_PRIVATE_FLAG;
static int gtm_futex_wake = FUTEX_WAKE | FUTEX_PRIVATE_FLAG;
void
futex_wait (std::atomic<int> *addr, int val)
{
long res;
res = sys_futex0 (addr, gtm_futex_wait, val);
if (__builtin_expect (res == -ENOSYS, 0))
{
gtm_futex_wait = FUTEX_WAIT;
gtm_futex_wake = FUTEX_WAKE;
res = sys_futex0 (addr, FUTEX_WAIT, val);
}
if (__builtin_expect (res < 0, 0))
{
if (res == -EWOULDBLOCK || res == -ETIMEDOUT)
;
else if (res == -EFAULT)
GTM_fatal ("futex failed (EFAULT %p)", addr);
else
GTM_fatal ("futex failed (%s)", strerror(-res));
}
}
long
futex_wake (std::atomic<int> *addr, int count)
{
long res = sys_futex0 (addr, gtm_futex_wake, count);
if (__builtin_expect (res == -ENOSYS, 0))
{
gtm_futex_wait = FUTEX_WAIT;
gtm_futex_wake = FUTEX_WAKE;
res = sys_futex0 (addr, FUTEX_WAKE, count);
}
if (__builtin_expect (res < 0, 0))
GTM_fatal ("futex failed (%s)", strerror(-res));
else
return res;
}
} // namespace GTM
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