include/linux/semaphore.h

0001 /* SPDX-License-Identifier: GPL-2.0-only */
0002 /*
0003  * Copyright (c) 2008 Intel Corporation
0004  * Author: Matthew Wilcox <willy@linux.intel.com>
0005  *
0006  * Please see kernel/locking/semaphore.c for documentation of these functions
0007  */
0008 #ifndef __LINUX_SEMAPHORE_H
0009 #define __LINUX_SEMAPHORE_H
0010
0011 #include <linux/list.h>
0012 #include <linux/spinlock.h>
0013
0014 /* Please don't access any members of this structure directly */
0015 struct semaphore {
0016     raw_spinlock_t      lock;
0017     unsigned int        count;
0018     struct list_head    wait_list;
0019 };
0020
0021 #define __SEMAPHORE_INITIALIZER(name, n)                \
0022 {                                   \
0023     .lock       = __RAW_SPIN_LOCK_UNLOCKED((name).lock),    \
0024     .count      = n,                        \
0025     .wait_list  = LIST_HEAD_INIT((name).wait_list),     \
0026 }
0027
0028 #define DEFINE_SEMAPHORE(name)  \
0029     struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
0030
0031 static inline void sema_init(struct semaphore *sem, int val)
0032 {
0033     static struct lock_class_key __key;
0034     *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
0035     lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0);
0036 }
0037
0038 extern void down(struct semaphore *sem);
0039 extern int __must_check down_interruptible(struct semaphore *sem);
0040 extern int __must_check down_killable(struct semaphore *sem);
0041 extern int __must_check down_trylock(struct semaphore *sem);
0042 extern int __must_check down_timeout(struct semaphore *sem, long jiffies);
0043 extern void up(struct semaphore *sem);
0044
0045 #endif /* __LINUX_SEMAPHORE_H */