diff -drupN a/include/linux/refcount.h b/include/linux/refcount.h --- a/include/linux/refcount.h 1970-01-01 03:00:00.000000000 +0300 +++ b/include/linux/refcount.h 2022-06-12 05:28:14.000000000 +0300 @@ -0,0 +1,102 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_REFCOUNT_H +#define _LINUX_REFCOUNT_H + +#include +#include +#include +#include + +/** + * struct 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 +# 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 */