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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - include/linux/rwsem-spinlock.h
1 /* rwsem-spinlock.h: fallback C implementation
3 * Copyright (c) 2001 David Howells (dhowells@redhat.com).
4 * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de>
5 * - Derived also from comments by Linus
8 #ifndef _LINUX_RWSEM_SPINLOCK_H
9 #define _LINUX_RWSEM_SPINLOCK_H
11 #ifndef _LINUX_RWSEM_H
12 #error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead"
17 * the rw-semaphore definition
18 * - if activity is 0 then there are no active readers or writers
19 * - if activity is +ve then that is the number of active readers
20 * - if activity is -1 then there is one active writer
21 * - if wait_list is not empty, then there are processes waiting for the semaphore
26 struct list_head wait_list
;
27 #ifdef CONFIG_DEBUG_LOCK_ALLOC
28 struct lockdep_map dep_map
;
32 #define RWSEM_UNLOCKED_VALUE 0x00000000
34 extern void __down_read(struct rw_semaphore
*sem
);
35 extern int __down_read_trylock(struct rw_semaphore
*sem
);
36 extern void __down_write(struct rw_semaphore
*sem
);
37 extern void __down_write_nested(struct rw_semaphore
*sem
, int subclass
);
38 extern int __down_write_trylock(struct rw_semaphore
*sem
);
39 extern void __up_read(struct rw_semaphore
*sem
);
40 extern void __up_write(struct rw_semaphore
*sem
);
41 extern void __downgrade_write(struct rw_semaphore
*sem
);
42 extern int rwsem_is_locked(struct rw_semaphore
*sem
);
44 #endif /* __KERNEL__ */
45 #endif /* _LINUX_RWSEM_SPINLOCK_H */