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- /* rwsem-spinlock.h: fallback C implementation
- *
- * Copyright (c) 2001 David Howells (dhowells@redhat.com).
- * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de>
- * - Derived also from comments by Linus
- */
- #ifndef _LINUX_RWSEM_SPINLOCK_H
- #define _LINUX_RWSEM_SPINLOCK_H
- #ifndef _LINUX_RWSEM_H
- #error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead"
- #endif
- #include <linux/spinlock.h>
- #include <linux/list.h>
- #ifdef __KERNEL__
- #include <linux/types.h>
- struct rwsem_waiter;
- /*
- * the rw-semaphore definition
- * - if activity is 0 then there are no active readers or writers
- * - if activity is +ve then that is the number of active readers
- * - if activity is -1 then there is one active writer
- * - if wait_list is not empty, then there are processes waiting for the semaphore
- */
- struct rw_semaphore {
- __s32 activity;
- spinlock_t wait_lock;
- struct list_head wait_list;
- #ifdef CONFIG_DEBUG_LOCK_ALLOC
- struct lockdep_map dep_map;
- #endif
- };
- #ifdef CONFIG_DEBUG_LOCK_ALLOC
- # define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
- #else
- # define __RWSEM_DEP_MAP_INIT(lockname)
- #endif
- #define __RWSEM_INITIALIZER(name) \
- { 0, __SPIN_LOCK_UNLOCKED(name.wait_lock), LIST_HEAD_INIT((name).wait_list) \
- __RWSEM_DEP_MAP_INIT(name) }
- #define DECLARE_RWSEM(name) \
- struct rw_semaphore name = __RWSEM_INITIALIZER(name)
- extern void __init_rwsem(struct rw_semaphore *sem, const char *name,
- struct lock_class_key *key);
- #define init_rwsem(sem) \
- do { \
- static struct lock_class_key __key; \
- \
- __init_rwsem((sem), #sem, &__key); \
- } while (0)
- extern void FASTCALL(__down_read(struct rw_semaphore *sem));
- extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem));
- extern void FASTCALL(__down_write(struct rw_semaphore *sem));
- extern void FASTCALL(__down_write_nested(struct rw_semaphore *sem, int subclass));
- extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem));
- extern void FASTCALL(__up_read(struct rw_semaphore *sem));
- extern void FASTCALL(__up_write(struct rw_semaphore *sem));
- extern void FASTCALL(__downgrade_write(struct rw_semaphore *sem));
- static inline int rwsem_is_locked(struct rw_semaphore *sem)
- {
- return (sem->activity != 0);
- }
- #endif /* __KERNEL__ */
- #endif /* _LINUX_RWSEM_SPINLOCK_H */
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