150 lines
3.1 KiB
C
150 lines
3.1 KiB
C
#ifndef _ALPHA_SEMAPHORE_H
|
|
#define _ALPHA_SEMAPHORE_H
|
|
|
|
/*
|
|
* SMP- and interrupt-safe semaphores..
|
|
*
|
|
* (C) Copyright 1996 Linus Torvalds
|
|
* (C) Copyright 1996, 2000 Richard Henderson
|
|
*/
|
|
|
|
#include <asm/current.h>
|
|
#include <asm/system.h>
|
|
#include <asm/atomic.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/wait.h>
|
|
#include <linux/rwsem.h>
|
|
|
|
struct semaphore {
|
|
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)
|
|
|
|
static inline void sema_init(struct semaphore *sem, int val)
|
|
{
|
|
/*
|
|
* Logically,
|
|
* *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
|
|
* except that gcc produces better initializing by parts yet.
|
|
*/
|
|
|
|
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 *);
|
|
extern void __down_failed(struct semaphore *);
|
|
extern int down_interruptible(struct semaphore *);
|
|
extern int __down_failed_interruptible(struct semaphore *);
|
|
extern int down_trylock(struct semaphore *);
|
|
extern void up(struct semaphore *);
|
|
extern void __up_wakeup(struct semaphore *);
|
|
|
|
/*
|
|
* Hidden out of line code is fun, but extremely messy. Rely on newer
|
|
* compilers to do a respectable job with this. The contention cases
|
|
* are handled out of line in arch/alpha/kernel/semaphore.c.
|
|
*/
|
|
|
|
static inline void __down(struct semaphore *sem)
|
|
{
|
|
long count;
|
|
might_sleep();
|
|
count = atomic_dec_return(&sem->count);
|
|
if (unlikely(count < 0))
|
|
__down_failed(sem);
|
|
}
|
|
|
|
static inline int __down_interruptible(struct semaphore *sem)
|
|
{
|
|
long count;
|
|
might_sleep();
|
|
count = atomic_dec_return(&sem->count);
|
|
if (unlikely(count < 0))
|
|
return __down_failed_interruptible(sem);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* down_trylock returns 0 on success, 1 if we failed to get the lock.
|
|
*/
|
|
|
|
static inline int __down_trylock(struct semaphore *sem)
|
|
{
|
|
long ret;
|
|
|
|
/* "Equivalent" C:
|
|
|
|
do {
|
|
ret = ldl_l;
|
|
--ret;
|
|
if (ret < 0)
|
|
break;
|
|
ret = stl_c = ret;
|
|
} while (ret == 0);
|
|
*/
|
|
__asm__ __volatile__(
|
|
"1: ldl_l %0,%1\n"
|
|
" subl %0,1,%0\n"
|
|
" blt %0,2f\n"
|
|
" stl_c %0,%1\n"
|
|
" beq %0,3f\n"
|
|
" mb\n"
|
|
"2:\n"
|
|
".subsection 2\n"
|
|
"3: br 1b\n"
|
|
".previous"
|
|
: "=&r" (ret), "=m" (sem->count)
|
|
: "m" (sem->count));
|
|
|
|
return ret < 0;
|
|
}
|
|
|
|
static inline void __up(struct semaphore *sem)
|
|
{
|
|
if (unlikely(atomic_inc_return(&sem->count) <= 0))
|
|
__up_wakeup(sem);
|
|
}
|
|
|
|
#if !defined(CONFIG_DEBUG_SEMAPHORE)
|
|
extern inline void down(struct semaphore *sem)
|
|
{
|
|
__down(sem);
|
|
}
|
|
extern inline int down_interruptible(struct semaphore *sem)
|
|
{
|
|
return __down_interruptible(sem);
|
|
}
|
|
extern inline int down_trylock(struct semaphore *sem)
|
|
{
|
|
return __down_trylock(sem);
|
|
}
|
|
extern inline void up(struct semaphore *sem)
|
|
{
|
|
__up(sem);
|
|
}
|
|
#endif
|
|
|
|
#endif
|