eb92f4ef32
Add sem_is_read/write_locked functions to the read/write semaphores, along the same lines of the *_is_locked spinlock functions. The swap token tuning patch uses sem_is_read_locked; sem_is_write_locked is added for completeness. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
67 lines
1.7 KiB
C
67 lines
1.7 KiB
C
/* $Id: rwsem.h,v 1.5 2001/11/18 00:12:56 davem Exp $
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* rwsem.h: R/W semaphores implemented using CAS
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*
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* Written by David S. Miller (davem@redhat.com), 2001.
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* Derived from asm-i386/rwsem.h
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*/
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#ifndef _SPARC64_RWSEM_H
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#define _SPARC64_RWSEM_H
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#ifndef _LINUX_RWSEM_H
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#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
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#endif
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#ifdef __KERNEL__
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <asm/rwsem-const.h>
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struct rwsem_waiter;
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struct rw_semaphore {
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signed int count;
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spinlock_t wait_lock;
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struct list_head wait_list;
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};
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#define __RWSEM_INITIALIZER(name) \
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{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) }
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#define DECLARE_RWSEM(name) \
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struct rw_semaphore name = __RWSEM_INITIALIZER(name)
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static __inline__ void init_rwsem(struct rw_semaphore *sem)
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{
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sem->count = RWSEM_UNLOCKED_VALUE;
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spin_lock_init(&sem->wait_lock);
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INIT_LIST_HEAD(&sem->wait_list);
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}
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extern void __down_read(struct rw_semaphore *sem);
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extern int __down_read_trylock(struct rw_semaphore *sem);
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extern void __down_write(struct rw_semaphore *sem);
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extern int __down_write_trylock(struct rw_semaphore *sem);
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extern void __up_read(struct rw_semaphore *sem);
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extern void __up_write(struct rw_semaphore *sem);
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extern void __downgrade_write(struct rw_semaphore *sem);
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static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
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{
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return atomic_add_return(delta, (atomic_t *)(&sem->count));
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}
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static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
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{
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atomic_add(delta, (atomic_t *)(&sem->count));
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}
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static inline int rwsem_is_locked(struct rw_semaphore *sem)
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{
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return (sem->count != 0);
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}
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#endif /* __KERNEL__ */
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#endif /* _SPARC64_RWSEM_H */
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