diff options
Diffstat (limited to 'linuxthreads/spinlock.h')
| -rw-r--r-- | linuxthreads/spinlock.h | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/linuxthreads/spinlock.h b/linuxthreads/spinlock.h index 96010e4636..d1da3c1094 100644 --- a/linuxthreads/spinlock.h +++ b/linuxthreads/spinlock.h @@ -12,6 +12,25 @@ /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */ /* GNU Library General Public License for more details. */ + +/* There are 2 compare and swap synchronization primitives with + different semantics: + + 1. compare_and_swap, which has acquire semantics (i.e. it + completes befor subsequent writes.) + 2. compare_and_swap_with_release_semantics, which has release + semantics (it completes after previous writes.) + + For those platforms on which they are the same. HAS_COMPARE_AND_SWAP + should be defined. For those platforms on which they are different, + HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS has to be defined. */ + +#ifndef HAS_COMPARE_AND_SWAP +#ifdef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS +#define HAS_COMPARE_AND_SWAP +#endif +#endif + #if defined(TEST_FOR_COMPARE_AND_SWAP) extern int __pthread_has_cas; @@ -29,6 +48,18 @@ static inline int compare_and_swap(long * ptr, long oldval, long newval, #elif defined(HAS_COMPARE_AND_SWAP) +#ifdef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS + +static inline int +compare_and_swap_with_release_semantics (long * ptr, long oldval, + long newval, int * spinlock) +{ + return __compare_and_swap_with_release_semantics (ptr, oldval, + newval); +} + +#endif + static inline int compare_and_swap(long * ptr, long oldval, long newval, int * spinlock) { @@ -48,6 +79,10 @@ static inline int compare_and_swap(long * ptr, long oldval, long newval, #endif +#ifndef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS +#define compare_and_swap_with_release_semantics compare_and_swap +#endif + /* Internal locks */ extern void internal_function __pthread_lock(struct _pthread_fastlock * lock, |