[mirror_ubuntu-zesty-kernel.git] / include / linux / lockref.h

#ifndef __LINUX_LOCKREF_H
#define __LINUX_LOCKREF_H

/*
 * Locked reference counts.
 *
 * These are different from just plain atomic refcounts in that they
 * are atomic with respect to the spinlock that goes with them.  In
 * particular, there can be implementations that don't actually get
 * the spinlock for the common decrement/increment operations, but they
 * still have to check that the operation is done semantically as if
 * the spinlock had been taken (using a cmpxchg operation that covers
 * both the lock and the count word, or using memory transactions, for
 * example).
 */

#include <linux/spinlock.h>

struct lockref {
	spinlock_t lock;
	unsigned int count;
};

extern void lockref_get(struct lockref *);
extern int lockref_get_not_zero(struct lockref *);
extern int lockref_get_or_lock(struct lockref *);
extern int lockref_put_or_lock(struct lockref *);

#endif /* __LINUX_LOCKREF_H */
Commit	Line	Data
0f8f2aaa WL	1	#ifndef __LINUX_LOCKREF_H
	2	#define __LINUX_LOCKREF_H
	3
	4	/*
	5	* Locked reference counts.
	6	*
	7	* These are different from just plain atomic refcounts in that they
	8	* are atomic with respect to the spinlock that goes with them. In
	9	* particular, there can be implementations that don't actually get
	10	* the spinlock for the common decrement/increment operations, but they
	11	* still have to check that the operation is done semantically as if
	12	* the spinlock had been taken (using a cmpxchg operation that covers
	13	* both the lock and the count word, or using memory transactions, for
	14	* example).
	15	*/
	16
	17	#include <linux/spinlock.h>
	18
	19	struct lockref {
	20	spinlock_t lock;
	21	unsigned int count;
	22	};
	23
2f4f12e5 LT	24	extern void lockref_get(struct lockref *);
	25	extern int lockref_get_not_zero(struct lockref *);
	26	extern int lockref_get_or_lock(struct lockref *);
	27	extern int lockref_put_or_lock(struct lockref *);
0f8f2aaa WL	28
0f8f2aaa WL	29	#endif /* __LINUX_LOCKREF_H */