1 /* Copyright (C) 2008, 2009, 2011 Free Software Foundation, Inc.
2 Contributed by Jakub Jelinek <jakub@redhat.com>.
4 This file is part of the GNU OpenMP Library (libgomp).
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)
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
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.
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/>. */
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.
29 A ptrlock has four states:
31 1 Owned by me, I get to write a pointer to ptrlock.
32 2 Some thread is waiting on the ptrlock.
33 >2 Ptrlock contains a valid pointer.
34 It is not valid to gain the ptrlock and then write a NULL to it. */
36 #ifndef GOMP_PTRLOCK_H
37 #define GOMP_PTRLOCK_H 1
39 typedef void *gomp_ptrlock_t;
41 static inline void gomp_ptrlock_init (gomp_ptrlock_t *ptrlock, void *ptr)
46 extern void *gomp_ptrlock_get_slow (gomp_ptrlock_t *ptrlock);
47 static inline void *gomp_ptrlock_get (gomp_ptrlock_t *ptrlock)
51 if ((uintptr_t) *ptrlock > 2)
55 if (__atomic_compare_exchange_n (ptrlock, &oldval, 1, false,
56 MEMMODEL_ACQUIRE, MEMMODEL_ACQUIRE))
59 return gomp_ptrlock_get_slow (ptrlock);
62 extern void gomp_ptrlock_set_slow (gomp_ptrlock_t *ptrlock);
63 static inline void gomp_ptrlock_set (gomp_ptrlock_t *ptrlock, void *ptr)
65 void *wait = __atomic_exchange_n (ptrlock, ptr, MEMMODEL_RELEASE);
66 if ((uintptr_t) wait != 1)
67 gomp_ptrlock_set_slow (ptrlock);
70 static inline void gomp_ptrlock_destroy (gomp_ptrlock_t *ptrlock)
74 #endif /* GOMP_PTRLOCK_H */