[mirror_ubuntu-zesty-kernel.git] / include / asm-sh / rwsem.h

/*
 * include/asm-ppc/rwsem.h: R/W semaphores for SH using the stuff
 * in lib/rwsem.c.
 */

#ifndef _ASM_SH_RWSEM_H
#define _ASM_SH_RWSEM_H

#ifdef __KERNEL__
#include <linux/list.h>
#include <linux/spinlock.h>
#include <asm/atomic.h>
#include <asm/system.h>

/*
 * the semaphore definition
 */
struct rw_semaphore {
	long		count;
#define RWSEM_UNLOCKED_VALUE		0x00000000
#define RWSEM_ACTIVE_BIAS		0x00000001
#define RWSEM_ACTIVE_MASK		0x0000ffff
#define RWSEM_WAITING_BIAS		(-0x00010000)
#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
	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)

extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem);
extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);

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);
}

/*
 * lock for reading
 */
static inline void __down_read(struct rw_semaphore *sem)
{
	if (atomic_inc_return((atomic_t *)(&sem->count)) > 0)
		smp_wmb();
	else
		rwsem_down_read_failed(sem);
}

static inline int __down_read_trylock(struct rw_semaphore *sem)
{
	int tmp;

	while ((tmp = sem->count) >= 0) {
		if (tmp == cmpxchg(&sem->count, tmp,
				   tmp + RWSEM_ACTIVE_READ_BIAS)) {
			smp_wmb();
			return 1;
		}
	}
	return 0;
}

/*
 * lock for writing
 */
static inline void __down_write(struct rw_semaphore *sem)
{
	int tmp;

	tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
				(atomic_t *)(&sem->count));
	if (tmp == RWSEM_ACTIVE_WRITE_BIAS)
		smp_wmb();
	else
		rwsem_down_write_failed(sem);
}

static inline int __down_write_trylock(struct rw_semaphore *sem)
{
	int tmp;

	tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
		      RWSEM_ACTIVE_WRITE_BIAS);
	smp_wmb();
	return tmp == RWSEM_UNLOCKED_VALUE;
}

/*
 * unlock after reading
 */
static inline void __up_read(struct rw_semaphore *sem)
{
	int tmp;

	smp_wmb();
	tmp = atomic_dec_return((atomic_t *)(&sem->count));
	if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)
		rwsem_wake(sem);
}

/*
 * unlock after writing
 */
static inline void __up_write(struct rw_semaphore *sem)
{
	smp_wmb();
	if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
			      (atomic_t *)(&sem->count)) < 0)
		rwsem_wake(sem);
}

/*
 * implement atomic add functionality
 */
static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
{
	atomic_add(delta, (atomic_t *)(&sem->count));
}

/*
 * downgrade write lock to read lock
 */
static inline void __downgrade_write(struct rw_semaphore *sem)
{
	int tmp;

	smp_wmb();
	tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
	if (tmp < 0)
		rwsem_downgrade_wake(sem);
}

/*
 * implement exchange and add functionality
 */
static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
{
	smp_mb();
	return atomic_add_return(delta, (atomic_t *)(&sem->count));
}

static inline int rwsem_is_locked(struct rw_semaphore *sem)
{
	return (sem->count != 0);
}

#endif /* __KERNEL__ */
#endif /* _ASM_SH_RWSEM_H */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* include/asm-ppc/rwsem.h: R/W semaphores for SH using the stuff
	3	* in lib/rwsem.c.
	4	*/
	5
	6	#ifndef _ASM_SH_RWSEM_H
	7	#define _ASM_SH_RWSEM_H
	8
	9	#ifdef __KERNEL__
	10	#include <linux/list.h>
	11	#include <linux/spinlock.h>
	12	#include <asm/atomic.h>
	13	#include <asm/system.h>
	14
	15	/*
	16	* the semaphore definition
	17	*/
	18	struct rw_semaphore {
	19	long count;
	20	#define RWSEM_UNLOCKED_VALUE 0x00000000
	21	#define RWSEM_ACTIVE_BIAS 0x00000001
	22	#define RWSEM_ACTIVE_MASK 0x0000ffff
	23	#define RWSEM_WAITING_BIAS (-0x00010000)
	24	#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
	25	#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
	26	spinlock_t wait_lock;
	27	struct list_head wait_list;
1da177e4 LT	28	};
1da177e4 LT	29
1da177e4 LT	30	#define __RWSEM_INITIALIZER(name) \
1da177e4 LT	31	{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \
61f4c3d6	32	LIST_HEAD_INIT((name).wait_list) }
1da177e4 LT	33
	34	#define DECLARE_RWSEM(name) \
	35	struct rw_semaphore name = __RWSEM_INITIALIZER(name)
	36
	37	extern struct rw_semaphore rwsem_down_read_failed(struct rw_semaphore sem);
	38	extern struct rw_semaphore rwsem_down_write_failed(struct rw_semaphore sem);
	39	extern struct rw_semaphore rwsem_wake(struct rw_semaphore sem);
	40	extern struct rw_semaphore rwsem_downgrade_wake(struct rw_semaphore sem);
	41
	42	static inline void init_rwsem(struct rw_semaphore *sem)
	43	{
	44	sem->count = RWSEM_UNLOCKED_VALUE;
	45	spin_lock_init(&sem->wait_lock);
	46	INIT_LIST_HEAD(&sem->wait_list);
1da177e4 LT	47	}
	48
	49	/*
	50	* lock for reading
	51	*/
	52	static inline void __down_read(struct rw_semaphore *sem)
	53	{
	54	if (atomic_inc_return((atomic_t *)(&sem->count)) > 0)
	55	smp_wmb();
	56	else
	57	rwsem_down_read_failed(sem);
	58	}
	59
	60	static inline int __down_read_trylock(struct rw_semaphore *sem)
	61	{
	62	int tmp;
	63
	64	while ((tmp = sem->count) >= 0) {
	65	if (tmp == cmpxchg(&sem->count, tmp,
	66	tmp + RWSEM_ACTIVE_READ_BIAS)) {
	67	smp_wmb();
	68	return 1;
	69	}
	70	}
	71	return 0;
	72	}
	73
	74	/*
	75	* lock for writing
	76	*/
	77	static inline void __down_write(struct rw_semaphore *sem)
	78	{
	79	int tmp;
	80
	81	tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
	82	(atomic_t *)(&sem->count));
	83	if (tmp == RWSEM_ACTIVE_WRITE_BIAS)
	84	smp_wmb();
	85	else
	86	rwsem_down_write_failed(sem);
	87	}
	88
	89	static inline int __down_write_trylock(struct rw_semaphore *sem)
	90	{
	91	int tmp;
	92
	93	tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
	94	RWSEM_ACTIVE_WRITE_BIAS);
	95	smp_wmb();
	96	return tmp == RWSEM_UNLOCKED_VALUE;
	97	}
	98
	99	/*
	100	* unlock after reading
	101	*/
	102	static inline void __up_read(struct rw_semaphore *sem)
	103	{
	104	int tmp;
	105
	106	smp_wmb();
	107	tmp = atomic_dec_return((atomic_t *)(&sem->count));
	108	if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)
	109	rwsem_wake(sem);
	110	}
111
112	/*
113	* unlock after writing
114	*/
115	static inline void __up_write(struct rw_semaphore *sem)
116	{
117	smp_wmb();
118	if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
119	(atomic_t *)(&sem->count)) < 0)
120	rwsem_wake(sem);
121	}
122
123	/*
124	* implement atomic add functionality
125	*/
126	static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
127	{
128	atomic_add(delta, (atomic_t *)(&sem->count));
129	}
130
131	/*
132	* downgrade write lock to read lock
133	*/
134	static inline void __downgrade_write(struct rw_semaphore *sem)
135	{
136	int tmp;
137
138	smp_wmb();
139	tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
140	if (tmp < 0)
141	rwsem_downgrade_wake(sem);
142	}
143
144	/*
145	* implement exchange and add functionality
146	*/
147	static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
148	{
149	smp_mb();
150	return atomic_add_return(delta, (atomic_t *)(&sem->count));
151	}
152
eb92f4ef RVR	153	static inline int rwsem_is_locked(struct rw_semaphore *sem)
	154	{
	155	return (sem->count != 0);
	156	}
	157
1da177e4 LT	158	#endif /* __KERNEL__ */
1da177e4 LT	159	#endif /* _ASM_SH_RWSEM_H */