103 lines
2.6 KiB
C
103 lines
2.6 KiB
C
|
/* SPDX-License-Identifier: GPL-2.0 */
|
||
|
|
#ifndef _LINUX_REFCOUNT_H
|
||
|
|
#define _LINUX_REFCOUNT_H
|
||
|
|
|
||
|
|
#include <linux/atomic.h>
|
||
|
|
#include <linux/mutex.h>
|
||
|
|
#include <linux/spinlock.h>
|
||
|
|
#include <linux/kernel.h>
|
||
|
|
|
||
|
|
/**
|
||
|
|
* refcount_t - variant of atomic_t specialized for reference counts
|
||
|
|
* @refs: atomic_t counter field
|
||
|
|
*
|
||
|
|
* The counter saturates at UINT_MAX and will not move once
|
||
|
|
* there. This avoids wrapping the counter and causing 'spurious'
|
||
|
|
* use-after-free bugs.
|
||
|
|
*/
|
||
|
|
typedef struct refcount_struct {
|
||
|
|
atomic_t refs;
|
||
|
|
} refcount_t;
|
||
|
|
|
||
|
|
#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
|
||
|
|
|
||
|
|
/**
|
||
|
|
* refcount_set - set a refcount's value
|
||
|
|
* @r: the refcount
|
||
|
|
* @n: value to which the refcount will be set
|
||
|
|
*/
|
||
|
|
static inline void refcount_set(refcount_t *r, unsigned int n)
|
||
|
|
{
|
||
|
|
atomic_set(&r->refs, n);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* refcount_read - get a refcount's value
|
||
|
|
* @r: the refcount
|
||
|
|
*
|
||
|
|
* Return: the refcount's value
|
||
|
|
*/
|
||
|
|
static inline unsigned int refcount_read(const refcount_t *r)
|
||
|
|
{
|
||
|
|
return atomic_read(&r->refs);
|
||
|
|
}
|
||
|
|
|
||
|
|
#ifdef CONFIG_REFCOUNT_FULL
|
||
|
|
extern __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r);
|
||
|
|
extern void refcount_add(unsigned int i, refcount_t *r);
|
||
|
|
|
||
|
|
extern __must_check bool refcount_inc_not_zero(refcount_t *r);
|
||
|
|
extern void refcount_inc(refcount_t *r);
|
||
|
|
|
||
|
|
extern __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r);
|
||
|
|
|
||
|
|
extern __must_check bool refcount_dec_and_test(refcount_t *r);
|
||
|
|
extern void refcount_dec(refcount_t *r);
|
||
|
|
#else
|
||
|
|
# ifdef CONFIG_ARCH_HAS_REFCOUNT
|
||
|
|
# include <asm/refcount.h>
|
||
|
|
# else
|
||
|
|
static inline __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r)
|
||
|
|
{
|
||
|
|
return atomic_add_unless(&r->refs, i, 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline void refcount_add(unsigned int i, refcount_t *r)
|
||
|
|
{
|
||
|
|
atomic_add(i, &r->refs);
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline __must_check bool refcount_inc_not_zero(refcount_t *r)
|
||
|
|
{
|
||
|
|
return atomic_add_unless(&r->refs, 1, 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline void refcount_inc(refcount_t *r)
|
||
|
|
{
|
||
|
|
atomic_inc(&r->refs);
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r)
|
||
|
|
{
|
||
|
|
return atomic_sub_and_test(i, &r->refs);
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline __must_check bool refcount_dec_and_test(refcount_t *r)
|
||
|
|
{
|
||
|
|
return atomic_dec_and_test(&r->refs);
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline void refcount_dec(refcount_t *r)
|
||
|
|
{
|
||
|
|
atomic_dec(&r->refs);
|
||
|
|
}
|
||
|
|
# endif /* !CONFIG_ARCH_HAS_REFCOUNT */
|
||
|
|
#endif /* CONFIG_REFCOUNT_FULL */
|
||
|
|
|
||
|
|
extern __must_check bool refcount_dec_if_one(refcount_t *r);
|
||
|
|
extern __must_check bool refcount_dec_not_one(refcount_t *r);
|
||
|
|
extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock);
|
||
|
|
extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock);
|
||
|
|
|
||
|
|
#endif /* _LINUX_REFCOUNT_H */
|