diff options
Diffstat (limited to 'include/asm-arm/spinlock.h')
| -rw-r--r-- | include/asm-arm/spinlock.h | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/include/asm-arm/spinlock.h b/include/asm-arm/spinlock.h index 406ca97a8ab2..01b7c26a3038 100644 --- a/include/asm-arm/spinlock.h +++ b/include/asm-arm/spinlock.h @@ -199,7 +199,21 @@ static inline void __raw_read_unlock(raw_rwlock_t *rw) : "cc"); } -#define __raw_read_trylock(lock) generic__raw_read_trylock(lock) +static inline int __raw_read_trylock(raw_rwlock_t *rw) +{ + unsigned long tmp, tmp2 = 1; + + __asm__ __volatile__( +"1: ldrex %0, [%2]\n" +" adds %0, %0, #1\n" +" strexpl %1, %0, [%2]\n" + : "=&r" (tmp), "+r" (tmp2) + : "r" (&rw->lock) + : "cc"); + + smp_mb(); + return tmp2 == 0; +} /* read_can_lock - would read_trylock() succeed? */ #define __raw_read_can_lock(x) ((x)->lock < 0x80000000) |