android_kernel_motorola_sm6225/include/asm-ia64/semaphore.h
Zoltan Menyhart 4b16bfbf8f [IA64] Fix bug in ia64 specific down() function
Chen, Kenneth W wrote:
> The memory order semantics for include/asm-ia64/semaphore.h:down()
> doesn't look right.  It is using atomic_dec_return, which eventually
> translate into ia64_fetch_and_add() that uses release semantics.
> Shouldn't it use acquire semantics?

Use ia64_fetchadd() instead of atomic_dec_return()

Acked-by: Ken Chen <kenneth.w.chen@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2006-01-17 14:04:00 -08:00

100 lines
2.1 KiB
C

#ifndef _ASM_IA64_SEMAPHORE_H
#define _ASM_IA64_SEMAPHORE_H
/*
* Copyright (C) 1998-2000 Hewlett-Packard Co
* Copyright (C) 1998-2000 David Mosberger-Tang <davidm@hpl.hp.com>
*/
#include <linux/wait.h>
#include <linux/rwsem.h>
#include <asm/atomic.h>
struct semaphore {
atomic_t count;
int sleepers;
wait_queue_head_t wait;
};
#define __SEMAPHORE_INITIALIZER(name, n) \
{ \
.count = ATOMIC_INIT(n), \
.sleepers = 0, \
.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)
{
*sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
}
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 int __down_trylock (struct semaphore * sem);
extern void __up (struct semaphore * sem);
/*
* Atomically decrement the semaphore's count. If it goes negative,
* block the calling thread in the TASK_UNINTERRUPTIBLE state.
*/
static inline void
down (struct semaphore *sem)
{
might_sleep();
if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)
__down(sem);
}
/*
* Atomically decrement the semaphore's count. If it goes negative,
* block the calling thread in the TASK_INTERRUPTIBLE state.
*/
static inline int
down_interruptible (struct semaphore * sem)
{
int ret = 0;
might_sleep();
if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)
ret = __down_interruptible(sem);
return ret;
}
static inline int
down_trylock (struct semaphore *sem)
{
int ret = 0;
if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)
ret = __down_trylock(sem);
return ret;
}
static inline void
up (struct semaphore * sem)
{
if (ia64_fetchadd(1, &sem->count.counter, rel) <= -1)
__up(sem);
}
#endif /* _ASM_IA64_SEMAPHORE_H */