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116 lines
2.3 KiB
116 lines
2.3 KiB
20 years ago
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/* rwsem.h: R/W semaphores, public interface
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*
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* Written by David Howells (dhowells@redhat.com).
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* Derived from asm-i386/semaphore.h
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*/
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#ifndef _LINUX_RWSEM_H
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#define _LINUX_RWSEM_H
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#include <linux/linkage.h>
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#define RWSEM_DEBUG 0
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#ifdef __KERNEL__
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#include <linux/config.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <asm/system.h>
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#include <asm/atomic.h>
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struct rw_semaphore;
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#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
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#include <linux/rwsem-spinlock.h> /* use a generic implementation */
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#else
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#include <asm/rwsem.h> /* use an arch-specific implementation */
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#endif
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#ifndef rwsemtrace
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#if RWSEM_DEBUG
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extern void FASTCALL(rwsemtrace(struct rw_semaphore *sem, const char *str));
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#else
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#define rwsemtrace(SEM,FMT)
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#endif
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#endif
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/*
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* lock for reading
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*/
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static inline void down_read(struct rw_semaphore *sem)
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{
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might_sleep();
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rwsemtrace(sem,"Entering down_read");
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__down_read(sem);
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rwsemtrace(sem,"Leaving down_read");
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}
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/*
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* trylock for reading -- returns 1 if successful, 0 if contention
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*/
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static inline int down_read_trylock(struct rw_semaphore *sem)
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{
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int ret;
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rwsemtrace(sem,"Entering down_read_trylock");
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ret = __down_read_trylock(sem);
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rwsemtrace(sem,"Leaving down_read_trylock");
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return ret;
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}
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/*
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* lock for writing
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*/
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static inline void down_write(struct rw_semaphore *sem)
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{
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might_sleep();
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rwsemtrace(sem,"Entering down_write");
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__down_write(sem);
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rwsemtrace(sem,"Leaving down_write");
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}
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/*
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* trylock for writing -- returns 1 if successful, 0 if contention
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*/
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static inline int down_write_trylock(struct rw_semaphore *sem)
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{
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int ret;
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rwsemtrace(sem,"Entering down_write_trylock");
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ret = __down_write_trylock(sem);
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rwsemtrace(sem,"Leaving down_write_trylock");
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return ret;
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}
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/*
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* release a read lock
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*/
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static inline void up_read(struct rw_semaphore *sem)
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{
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rwsemtrace(sem,"Entering up_read");
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__up_read(sem);
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rwsemtrace(sem,"Leaving up_read");
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}
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/*
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* release a write lock
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*/
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static inline void up_write(struct rw_semaphore *sem)
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{
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rwsemtrace(sem,"Entering up_write");
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__up_write(sem);
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rwsemtrace(sem,"Leaving up_write");
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}
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/*
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* downgrade write lock to read lock
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*/
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static inline void downgrade_write(struct rw_semaphore *sem)
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{
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rwsemtrace(sem,"Entering downgrade_write");
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__downgrade_write(sem);
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rwsemtrace(sem,"Leaving downgrade_write");
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}
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#endif /* __KERNEL__ */
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#endif /* _LINUX_RWSEM_H */
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