1 /* Copyright (C) 2005, 2009 Free Software Foundation, Inc. 2 Contributed by Richard Henderson <rth@redhat.com>. 3 4 This file is part of the GNU OpenMP Library (libgomp). 5 6 Libgomp is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3, or (at your option) 9 any later version. 10 11 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY 12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 13 FOR A PARTICULAR PURPOSE. See the GNU General Public License for 14 more details. 15 16 Under Section 7 of GPL version 3, you are granted additional 17 permissions described in the GCC Runtime Library Exception, version 18 3.1, as published by the Free Software Foundation. 19 20 You should have received a copy of the GNU General Public License and 21 a copy of the GCC Runtime Library Exception along with this program; 22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 <http://www.gnu.org/licenses/>. */ 24 25 /* This is a Linux specific implementation of a mutex synchronization 26 mechanism for libgomp. This type is private to the library. This 27 implementation uses atomic instructions and the futex syscall. */ 28 29 #ifndef GOMP_MUTEX_H 30 #define GOMP_MUTEX_H 1 31 32 typedef int gomp_mutex_t; 33 34 #define GOMP_MUTEX_INIT_0 1 35 36 static inline void gomp_mutex_init (gomp_mutex_t *mutex) 37 { 38 *mutex = 0; 39 } 40 41 extern void gomp_mutex_lock_slow (gomp_mutex_t *mutex); 42 static inline void gomp_mutex_lock (gomp_mutex_t *mutex) 43 { 44 if (!__sync_bool_compare_and_swap (mutex, 0, 1)) 45 gomp_mutex_lock_slow (mutex); 46 } 47 48 extern void gomp_mutex_unlock_slow (gomp_mutex_t *mutex); 49 static inline void gomp_mutex_unlock (gomp_mutex_t *mutex) 50 { 51 /* Warning: By definition __sync_lock_test_and_set() does not have 52 proper memory barrier semantics for a mutex unlock operation. 53 However, this default implementation is written assuming that it 54 does, which is true for some targets. 55 56 Targets that require additional memory barriers before 57 __sync_lock_test_and_set to achieve the release semantics of 58 mutex unlock, are encouraged to include 59 "config/linux/ia64/mutex.h" in a target specific mutex.h instead 60 of using this file. */ 61 int val = __sync_lock_test_and_set (mutex, 0); 62 if (__builtin_expect (val > 1, 0)) 63 gomp_mutex_unlock_slow (mutex); 64 } 65 66 static inline void gomp_mutex_destroy (gomp_mutex_t *mutex) 67 { 68 } 69 70 #endif /* GOMP_MUTEX_H */ 71