| 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
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| 2 | /* |
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| 3 | * Copyright (c) 2008 Intel Corporation |
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| 4 | * Author: Matthew Wilcox <willy@linux.intel.com> |
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| 5 | * |
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| 6 | * Please see kernel/locking/semaphore.c for documentation of these functions |
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| 7 | */ |
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| 8 | #ifndef __LINUX_SEMAPHORE_H |
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| 9 | #define __LINUX_SEMAPHORE_H |
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| 10 | |
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| 11 | #include <linux/list.h> |
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| 12 | #include <linux/spinlock.h> |
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| 13 | |
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| 14 | /* Please don't access any members of this structure directly */ |
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| 15 | struct semaphore { |
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| 16 | raw_spinlock_t lock; |
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| 17 | unsigned int count; |
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| 18 | struct list_head wait_list; |
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| 19 | |
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| 20 | #ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER |
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| 21 | unsigned long last_holder; |
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| 22 | #endif |
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| 23 | }; |
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| 24 | |
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| 25 | #ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER |
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| 26 | #define __LAST_HOLDER_SEMAPHORE_INITIALIZER \ |
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| 27 | , .last_holder = 0UL |
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| 28 | #else |
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| 29 | #define __LAST_HOLDER_SEMAPHORE_INITIALIZER |
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| 30 | #endif |
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| 31 | |
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| 32 | #define __SEMAPHORE_INITIALIZER(name, n) \ |
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| 33 | { \ |
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| 34 | .lock = __RAW_SPIN_LOCK_UNLOCKED((name).lock), \ |
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| 35 | .count = n, \ |
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| 36 | .wait_list = LIST_HEAD_INIT((name).wait_list) \ |
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| 37 | __LAST_HOLDER_SEMAPHORE_INITIALIZER \ |
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| 38 | } |
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| 39 | |
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| 40 | /* |
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| 41 | * Unlike mutexes, binary semaphores do not have an owner, so up() can |
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| 42 | * be called in a different thread from the one which called down(). |
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| 43 | * It is also safe to call down_trylock() and up() from interrupt |
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| 44 | * context. |
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| 45 | */ |
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| 46 | #define DEFINE_SEMAPHORE(_name, _n) \ |
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| 47 | struct semaphore _name = __SEMAPHORE_INITIALIZER(_name, _n) |
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| 48 | |
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| 49 | static inline void sema_init(struct semaphore *sem, int val) |
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| 50 | { |
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| 51 | static struct lock_class_key __key; |
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| 52 | *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val); |
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| 53 | lockdep_init_map(lock: &sem->lock.dep_map, name: "semaphore->lock" , key: &__key, subclass: 0); |
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| 54 | } |
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| 55 | |
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| 56 | extern void down(struct semaphore *sem); |
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| 57 | extern int __must_check down_interruptible(struct semaphore *sem); |
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| 58 | extern int __must_check down_killable(struct semaphore *sem); |
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| 59 | extern int __must_check down_trylock(struct semaphore *sem); |
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| 60 | extern int __must_check down_timeout(struct semaphore *sem, long jiffies); |
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| 61 | extern void up(struct semaphore *sem); |
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| 62 | extern unsigned long sem_last_holder(struct semaphore *sem); |
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| 63 | |
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| 64 | #endif /* __LINUX_SEMAPHORE_H */ |
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| 65 | |
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