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git.proxmox.com Git - mirror_ubuntu-eoan-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"
15 #include <linux/spinlock.h>
16 #include <linux/list.h>
20 #include <linux/types.h>
25 * the rw-semaphore definition
26 * - if activity is 0 then there are no active readers or writers
27 * - if activity is +ve then that is the number of active readers
28 * - if activity is -1 then there is one active writer
29 * - if wait_list is not empty, then there are processes waiting for the semaphore
34 struct list_head wait_list
;
35 #ifdef CONFIG_DEBUG_LOCK_ALLOC
36 struct lockdep_map dep_map
;
40 #ifdef CONFIG_DEBUG_LOCK_ALLOC
41 # define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
43 # define __RWSEM_DEP_MAP_INIT(lockname)
46 #define __RWSEM_INITIALIZER(name) \
47 { 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __RWSEM_DEP_MAP_INIT(name) }
49 #define DECLARE_RWSEM(name) \
50 struct rw_semaphore name = __RWSEM_INITIALIZER(name)
52 extern void __init_rwsem(struct rw_semaphore
*sem
, const char *name
,
53 struct lock_class_key
*key
);
55 #define init_rwsem(sem) \
57 static struct lock_class_key __key; \
59 __init_rwsem((sem), #sem, &__key); \
62 extern void FASTCALL(__down_read(struct rw_semaphore
*sem
));
63 extern int FASTCALL(__down_read_trylock(struct rw_semaphore
*sem
));
64 extern void FASTCALL(__down_write(struct rw_semaphore
*sem
));
65 extern void FASTCALL(__down_write_nested(struct rw_semaphore
*sem
, int subclass
));
66 extern int FASTCALL(__down_write_trylock(struct rw_semaphore
*sem
));
67 extern void FASTCALL(__up_read(struct rw_semaphore
*sem
));
68 extern void FASTCALL(__up_write(struct rw_semaphore
*sem
));
69 extern void FASTCALL(__downgrade_write(struct rw_semaphore
*sem
));
71 static inline int rwsem_is_locked(struct rw_semaphore
*sem
)
73 return (sem
->activity
!= 0);
76 #endif /* __KERNEL__ */
77 #endif /* _LINUX_RWSEM_SPINLOCK_H */