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