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(name.wait_lock), LIST_HEAD_INIT((name).wait_list) \
48 __RWSEM_DEP_MAP_INIT(name) }
50 #define DECLARE_RWSEM(name) \
51 struct rw_semaphore name = __RWSEM_INITIALIZER(name)
53 extern void __init_rwsem(struct rw_semaphore
*sem
, const char *name
,
54 struct lock_class_key
*key
);
56 #define init_rwsem(sem) \
58 static struct lock_class_key __key; \
60 __init_rwsem((sem), #sem, &__key); \
63 extern void __down_read(struct rw_semaphore
*sem
);
64 extern int __down_read_trylock(struct rw_semaphore
*sem
);
65 extern void __down_write(struct rw_semaphore
*sem
);
66 extern void __down_write_nested(struct rw_semaphore
*sem
, int subclass
);
67 extern int __down_write_trylock(struct rw_semaphore
*sem
);
68 extern void __up_read(struct rw_semaphore
*sem
);
69 extern void __up_write(struct rw_semaphore
*sem
);
70 extern void __downgrade_write(struct rw_semaphore
*sem
);
71 extern int rwsem_is_locked(struct rw_semaphore
*sem
);
73 #endif /* __KERNEL__ */
74 #endif /* _LINUX_RWSEM_SPINLOCK_H */
This page took 0.032171 seconds and 5 git commands to generate.