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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_REFCOUNT_H
#define _LINUX_REFCOUNT_H
#include <linux/atomic.h>
#include <linux/compiler.h>
#include <linux/limits.h>
#include <linux/spinlock_types.h>
struct mutex;
/**
* struct refcount_t - variant of atomic_t specialized for reference counts
* @refs: atomic_t counter field
*
* The counter saturates at REFCOUNT_SATURATED 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, 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
#define REFCOUNT_MAX (UINT_MAX - 1)
#define REFCOUNT_SATURATED UINT_MAX
extern __must_check bool refcount_add_not_zero(int i, refcount_t *r);
extern void refcount_add(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(int i, refcount_t *r);
extern __must_check bool refcount_dec_and_test(refcount_t *r);
extern void refcount_dec(refcount_t *r);
#else
#define REFCOUNT_MAX INT_MAX
#define REFCOUNT_SATURATED (INT_MIN / 2)
# ifdef CONFIG_ARCH_HAS_REFCOUNT
# include <asm/refcount.h>
# else
static inline __must_check bool refcount_add_not_zero(int i, refcount_t *r)
{
return atomic_add_unless(&r->refs, i, 0);
}
static inline void refcount_add(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(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);
extern __must_check bool refcount_dec_and_lock_irqsave(refcount_t *r,
spinlock_t *lock,
unsigned long *flags);
#endif /* _LINUX_REFCOUNT_H */
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