semaphore.h

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/*
 * Copyright (c) 2008 Intel Corporation
 * Author: Matthew Wilcox <[email protected]>
 *
 * Distributed under the terms of the GNU GPL, version 2
 *
 * Please see kernel/semaphore.c for documentation of these functions
 */
#ifndef __LINUX_SEMAPHORE_H
#define __LINUX_SEMAPHORE_H

#include <linux/list.h>
#include <linux/spinlock.h>

/* Please don't access any members of this structure directly */
struct semaphore {
    raw_spinlock_t      lock;
    unsigned int        count;
    struct list_head    wait_list;
};

#define __SEMAPHORE_INITIALIZER(name, n)                \
{                                   \
    .lock       = __RAW_SPIN_LOCK_UNLOCKED((name).lock),    \
    .count      = n,                        \
    .wait_list  = LIST_HEAD_INIT((name).wait_list),     \
}

#define DEFINE_SEMAPHORE(name)  \
    struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)

static inline void sema_init(struct semaphore *sem, int val)
{
    static struct lock_class_key __key;
    *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
    lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0);
}

extern void down(struct semaphore *sem);
extern int __must_check down_interruptible(struct semaphore *sem);
extern int __must_check down_killable(struct semaphore *sem);
extern int __must_check down_trylock(struct semaphore *sem);
extern int __must_check down_timeout(struct semaphore *sem, long jiffies);
extern void up(struct semaphore *sem);

#endif /* __LINUX_SEMAPHORE_H */