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/* Mutex implementation for libgomp plugins.
Copyright (C) 2025-2026 Free Software Foundation, Inc.
Contributed by BayLibre
This file is part of the GNU Offloading and Multi Processing Library
(libgomp).
Libgomp 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.
Libgomp 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/>. */
/* This is a minimal implementation of the gomp_mutex_t spinlocks, but
without all the dependencies used by the config/linux/mutex implementation.
At the time of writing, this is only used by simple_alloc which has
short-lived locks and should be fine with these. The actual locks are in
a header file, so only the fallback "slow" functions are needed here. */
#include "config.h"
#include <unistd.h>
#include "libgomp.h"
#ifndef HAVE_SYNC_BUILTINS
#error "HAVE_SYNC_BUILTINS is required to build this"
#endif
void
gomp_mutex_lock_slow (gomp_mutex_t *mutex, int oldval)
{
while (oldval == 1)
{
usleep (1);
oldval = __atomic_exchange_n (mutex, 1, __ATOMIC_ACQUIRE);
}
}
void
gomp_mutex_unlock_slow (gomp_mutex_t *mutex)
{
GOMP_PLUGIN_fatal ("gomp_mutex_unlock_slow should be unreachable");
}
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