/* 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 voidgomp_mutex_lock_slow (gomp_mutex_t *mutex, int oldval){  while (oldval == 1)    {      usleep (1);      oldval = __atomic_exchange_n (mutex, 1, __ATOMIC_ACQUIRE);    }} voidgomp_mutex_unlock_slow (gomp_mutex_t *mutex){  GOMP_PLUGIN_fatal ("gomp_mutex_unlock_slow should be unreachable");}