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Diffstat (limited to 'include/asm-powerpc/semaphore.h')
-rw-r--r-- | include/asm-powerpc/semaphore.h | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/include/asm-powerpc/semaphore.h b/include/asm-powerpc/semaphore.h new file mode 100644 index 00000000000..57369d2cade --- /dev/null +++ b/include/asm-powerpc/semaphore.h @@ -0,0 +1,95 @@ +#ifndef _ASM_POWERPC_SEMAPHORE_H +#define _ASM_POWERPC_SEMAPHORE_H + +/* + * Remove spinlock-based RW semaphores; RW semaphore definitions are + * now in rwsem.h and we use the generic lib/rwsem.c implementation. + * Rework semaphores to use atomic_dec_if_positive. + * -- Paul Mackerras (paulus@samba.org) + */ + +#ifdef __KERNEL__ + +#include <asm/atomic.h> +#include <asm/system.h> +#include <linux/wait.h> +#include <linux/rwsem.h> + +struct semaphore { + /* + * Note that any negative value of count is equivalent to 0, + * but additionally indicates that some process(es) might be + * sleeping on `wait'. + */ + atomic_t count; + wait_queue_head_t wait; +}; + +#define __SEMAPHORE_INITIALIZER(name, n) \ +{ \ + .count = ATOMIC_INIT(n), \ + .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ +} + +#define __DECLARE_SEMAPHORE_GENERIC(name, count) \ + struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) + +#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1) +#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0) + +static inline void sema_init (struct semaphore *sem, int val) +{ + atomic_set(&sem->count, val); + init_waitqueue_head(&sem->wait); +} + +static inline void init_MUTEX (struct semaphore *sem) +{ + sema_init(sem, 1); +} + +static inline void init_MUTEX_LOCKED (struct semaphore *sem) +{ + sema_init(sem, 0); +} + +extern void __down(struct semaphore * sem); +extern int __down_interruptible(struct semaphore * sem); +extern void __up(struct semaphore * sem); + +static inline void down(struct semaphore * sem) +{ + might_sleep(); + + /* + * Try to get the semaphore, take the slow path if we fail. + */ + if (unlikely(atomic_dec_return(&sem->count) < 0)) + __down(sem); +} + +static inline int down_interruptible(struct semaphore * sem) +{ + int ret = 0; + + might_sleep(); + + if (unlikely(atomic_dec_return(&sem->count) < 0)) + ret = __down_interruptible(sem); + return ret; +} + +static inline int down_trylock(struct semaphore * sem) +{ + return atomic_dec_if_positive(&sem->count) < 0; +} + +static inline void up(struct semaphore * sem) +{ + if (unlikely(atomic_inc_return(&sem->count) <= 0)) + __up(sem); +} + +#endif /* __KERNEL__ */ + +#endif /* _ASM_POWERPC_SEMAPHORE_H */ |