forked from luck/tmp_suning_uos_patched
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 $
|
|
* rwsem.h: R/W semaphores implemented using CAS
|
|
*
|
|
* Written by David S. Miller (davem@redhat.com), 2001.
|
|
* Derived from asm-i386/rwsem.h
|
|
*/
|
|
#ifndef _SPARC64_RWSEM_H
|
|
#define _SPARC64_RWSEM_H
|
|
|
|
#ifndef _LINUX_RWSEM_H
|
|
#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
|
|
#endif
|
|
|
|
#ifdef __KERNEL__
|
|
|
|
#include <linux/list.h>
|
|
#include <linux/spinlock.h>
|
|
#include <asm/rwsem-const.h>
|
|
|
|
struct rwsem_waiter;
|
|
|
|
struct rw_semaphore {
|
|
signed int count;
|
|
spinlock_t wait_lock;
|
|
struct list_head wait_list;
|
|
};
|
|
|
|
#define __RWSEM_INITIALIZER(name) \
|
|
{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) }
|
|
|
|
#define DECLARE_RWSEM(name) \
|
|
struct rw_semaphore name = __RWSEM_INITIALIZER(name)
|
|
|
|
static __inline__ void init_rwsem(struct rw_semaphore *sem)
|
|
{
|
|
sem->count = RWSEM_UNLOCKED_VALUE;
|
|
spin_lock_init(&sem->wait_lock);
|
|
INIT_LIST_HEAD(&sem->wait_list);
|
|
}
|
|
|
|
extern void __down_read(struct rw_semaphore *sem);
|
|
extern int __down_read_trylock(struct rw_semaphore *sem);
|
|
extern void __down_write(struct rw_semaphore *sem);
|
|
extern int __down_write_trylock(struct rw_semaphore *sem);
|
|
extern void __up_read(struct rw_semaphore *sem);
|
|
extern void __up_write(struct rw_semaphore *sem);
|
|
extern void __downgrade_write(struct rw_semaphore *sem);
|
|
|
|
static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
|
|
{
|
|
return atomic_add_return(delta, (atomic_t *)(&sem->count));
|
|
}
|
|
|
|
static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
|
|
{
|
|
atomic_add(delta, (atomic_t *)(&sem->count));
|
|
}
|
|
|
|
static inline int rwsem_is_locked(struct rw_semaphore *sem)
|
|
{
|
|
return (sem->count != 0);
|
|
}
|
|
|
|
#endif /* __KERNEL__ */
|
|
|
|
#endif /* _SPARC64_RWSEM_H */
|