LXR linux/include/linux/semaphore.h

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * Copyright (c) 2008 Intel Corporation
   4 * Author: Matthew Wilcox <willy@linux.intel.com>
   5 *
   6 * Please see kernel/locking/semaphore.c for documentation of these functions
   7 */
   8#ifndef __LINUX_SEMAPHORE_H
   9#define __LINUX_SEMAPHORE_H
  10
  11#include <linux/list.h>
  12#include <linux/spinlock.h>
  13
  14/* Please don't access any members of this structure directly */
  15struct semaphore {
  16        raw_spinlock_t          lock;
  17        unsigned int            count;
  18        struct list_head        wait_list;
  19};
  20
  21#define __SEMAPHORE_INITIALIZER(name, n)                                \
  22{                                                                       \
  23        .lock           = __RAW_SPIN_LOCK_UNLOCKED((name).lock),        \
  24        .count          = n,                                            \
  25        .wait_list      = LIST_HEAD_INIT((name).wait_list),             \
  26}
  27
  28#define DEFINE_SEMAPHORE(name)  \
  29        struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
  30
  31static inline void sema_init(struct semaphore *sem, int val)
  32{
  33        static struct lock_class_key __key;
  34        *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
  35        lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0);
  36}
  37
  38extern void down(struct semaphore *sem);
  39extern int __must_check down_interruptible(struct semaphore *sem);
  40extern int __must_check down_killable(struct semaphore *sem);
  41extern int __must_check down_trylock(struct semaphore *sem);
  42extern int __must_check down_timeout(struct semaphore *sem, long jiffies);
  43extern void up(struct semaphore *sem);
  44
  45#endif /* __LINUX_SEMAPHORE_H */
  46