1 /* 2 * Copyright (c) 2008 Intel Corporation 3 * Author: Matthew Wilcox <willy@linux.intel.com> 4 * 5 * Distributed under the terms of the GNU GPL, version 2 6 * 7 * Please see kernel/locking/semaphore.c for documentation of these functions 8 */ 9 #ifndef __LINUX_SEMAPHORE_H 10 #define __LINUX_SEMAPHORE_H 11 12 #include <linux/list.h> 13 #include <linux/spinlock.h> 14 15 /* Please don't access any members of this structure directly */ 16 struct semaphore { 17 raw_spinlock_t lock; 18 unsigned int count; 19 struct list_head wait_list; 20 }; 21 22 #define __SEMAPHORE_INITIALIZER(name, n) \ 23 { \ 24 .lock = __RAW_SPIN_LOCK_UNLOCKED((name).lock), \ 25 .count = n, \ 26 .wait_list = LIST_HEAD_INIT((name).wait_list), \ 27 } 28 29 #define DEFINE_SEMAPHORE(name) \ 30 struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1) 31 32 static inline void sema_init(struct semaphore *sem, int val) 33 { 34 static struct lock_class_key __key; 35 *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val); 36 lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0); 37 } 38 39 extern void down(struct semaphore *sem); 40 extern int __must_check down_interruptible(struct semaphore *sem); 41 extern int __must_check down_killable(struct semaphore *sem); 42 extern int __must_check down_trylock(struct semaphore *sem); 43 extern int __must_check down_timeout(struct semaphore *sem, long jiffies); 44 extern void up(struct semaphore *sem); 45 46 #endif /* __LINUX_SEMAPHORE_H */ 47