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/* SMP- and interrupt-safe semaphores.
* PA-RISC version by Matthew Wilcox
*
* Linux/PA-RISC Project (http://www.parisc-linux.org/)
* Copyright (C) 1996 Linus Torvalds
* Copyright (C) 1999-2001 Matthew Wilcox < willy at debian d0T org >
* Copyright (C) 2000 Grant Grundler < grundler a debian org >
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _ASM_PARISC_SEMAPHORE_H
#define _ASM_PARISC_SEMAPHORE_H
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/rwsem.h>
#include <asm/system.h>
/*
* The `count' is initialised to the number of people who are allowed to
* take the lock. (Normally we want a mutex, so this is `1'). if
* `count' is positive, the lock can be taken. if it's 0, no-one is
* waiting on it. if it's -1, at least one task is waiting.
*/
struct semaphore {
spinlock_t sentry;
int count;
wait_queue_head_t wait;
};
#define __SEMAPHORE_INITIALIZER(name, n) \
{ \
.sentry = SPIN_LOCK_UNLOCKED, \
.count = 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)
{
*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);
}
static inline int sem_getcount(struct semaphore *sem)
{
return sem->count;
}
asmlinkage void __down(struct semaphore * sem);
asmlinkage int __down_interruptible(struct semaphore * sem);
asmlinkage void __up(struct semaphore * sem);
/* Semaphores can be `tried' from irq context. So we have to disable
* interrupts while we're messing with the semaphore. Sorry.
*/
static inline void down(struct semaphore * sem)
{
might_sleep();
spin_lock_irq(&sem->sentry);
if (sem->count > 0) {
sem->count--;
} else {
__down(sem);
}
spin_unlock_irq(&sem->sentry);
}
static inline int down_interruptible(struct semaphore * sem)
{
int ret = 0;
might_sleep();
spin_lock_irq(&sem->sentry);
if (sem->count > 0) {
sem->count--;
} else {
ret = __down_interruptible(sem);
}
spin_unlock_irq(&sem->sentry);
return ret;
}
/*
* down_trylock returns 0 on success, 1 if we failed to get the lock.
* May not sleep, but must preserve irq state
*/
static inline int down_trylock(struct semaphore * sem)
{
unsigned long flags;
int count;
spin_lock_irqsave(&sem->sentry, flags);
count = sem->count - 1;
if (count >= 0)
sem->count = count;
spin_unlock_irqrestore(&sem->sentry, flags);
return (count < 0);
}
/*
* Note! This is subtle. We jump to wake people up only if
* the semaphore was negative (== somebody was waiting on it).
*/
static inline void up(struct semaphore * sem)
{
unsigned long flags;
spin_lock_irqsave(&sem->sentry, flags);
if (sem->count < 0) {
__up(sem);
} else {
sem->count++;
}
spin_unlock_irqrestore(&sem->sentry, flags);
}
#endif /* _ASM_PARISC_SEMAPHORE_H */
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