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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (c) 2008 Intel Corporation
* Author: Matthew Wilcox <willy@linux.intel.com>
*
* Please see kernel/locking/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), \
}
/*
* Unlike mutexes, binary semaphores do not have an owner, so up() can
* be called in a different thread from the one which called down().
* It is also safe to call down_trylock() and up() from interrupt
* context.
*/
#define DEFINE_SEMAPHORE(_name, _n) \
struct semaphore _name = __SEMAPHORE_INITIALIZER(_name, _n)
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 */
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