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3e456101 | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
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2 | /* |
3 | * Copyright (c) 2008 Intel Corporation | |
4 | * Author: Matthew Wilcox <willy@linux.intel.com> | |
5 | * | |
2dd6fd2e | 6 | * Please see kernel/locking/semaphore.c for documentation of these functions |
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7 | */ |
8 | #ifndef __LINUX_SEMAPHORE_H | |
9 | #define __LINUX_SEMAPHORE_H | |
10 | ||
11 | #include <linux/list.h> | |
12 | #include <linux/spinlock.h> | |
13 | ||
714493cd | 14 | /* Please don't access any members of this structure directly */ |
64ac24e7 | 15 | struct semaphore { |
8292c9e1 | 16 | raw_spinlock_t lock; |
b17170b2 | 17 | unsigned int count; |
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18 | struct list_head wait_list; |
19 | }; | |
20 | ||
21 | #define __SEMAPHORE_INITIALIZER(name, n) \ | |
22 | { \ | |
8292c9e1 | 23 | .lock = __RAW_SPIN_LOCK_UNLOCKED((name).lock), \ |
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24 | .count = n, \ |
25 | .wait_list = LIST_HEAD_INIT((name).wait_list), \ | |
26 | } | |
27 | ||
48380368 PZ |
28 | /* |
29 | * Unlike mutexes, binary semaphores do not have an owner, so up() can | |
30 | * be called in a different thread from the one which called down(). | |
31 | * It is also safe to call down_trylock() and up() from interrupt | |
32 | * context. | |
33 | */ | |
34 | #define DEFINE_SEMAPHORE(_name, _n) \ | |
35 | struct semaphore _name = __SEMAPHORE_INITIALIZER(_name, _n) | |
febc88c5 | 36 | |
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37 | static inline void sema_init(struct semaphore *sem, int val) |
38 | { | |
39 | static struct lock_class_key __key; | |
40 | *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val); | |
41 | lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0); | |
42 | } | |
43 | ||
64ac24e7 | 44 | extern void down(struct semaphore *sem); |
64ac24e7 | 45 | extern int __must_check down_interruptible(struct semaphore *sem); |
f06d9686 | 46 | extern int __must_check down_killable(struct semaphore *sem); |
64ac24e7 | 47 | extern int __must_check down_trylock(struct semaphore *sem); |
f1241c87 | 48 | extern int __must_check down_timeout(struct semaphore *sem, long jiffies); |
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49 | extern void up(struct semaphore *sem); |
50 | ||
51 | #endif /* __LINUX_SEMAPHORE_H */ |