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/* $OpenBSD: kref.h,v 1.1 2019/04/14 10:14:53 jsg Exp $ */
/*
* Copyright (c) 2015 Mark Kettenis
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef _LINUX_KREF_H
#define _LINUX_KREF_H
#include <sys/types.h>
#include <sys/rwlock.h>
#include <sys/atomic.h>
#include <linux/atomic.h>
#include <linux/compiler.h>
#include <linux/refcount.h>
struct kref {
uint32_t refcount;
};
static inline void
kref_init(struct kref *ref)
{
ref->refcount = 1;
}
static inline unsigned int
kref_read(const struct kref *ref)
{
return atomic_read(&ref->refcount);
}
static inline void
kref_get(struct kref *ref)
{
atomic_inc_int(&ref->refcount);
}
static inline int
kref_get_unless_zero(struct kref *ref)
{
if (ref->refcount != 0) {
atomic_inc_int(&ref->refcount);
return (1);
} else {
return (0);
}
}
static inline int
kref_put(struct kref *ref, void (*release)(struct kref *ref))
{
if (atomic_dec_int_nv(&ref->refcount) == 0) {
release(ref);
return 1;
}
return 0;
}
static inline void
kref_sub(struct kref *ref, unsigned int v, void (*release)(struct kref *ref))
{
if (atomic_sub_int_nv(&ref->refcount, v) == 0)
release(ref);
}
static inline int
kref_put_mutex(struct kref *kref, void (*release)(struct kref *kref),
struct rwlock *lock)
{
if (!atomic_add_unless(&kref->refcount, -1, 1)) {
rw_enter_write(lock);
if (likely(atomic_dec_and_test(&kref->refcount))) {
release(kref);
return 1;
}
rw_exit_write(lock);
return 0;
}
return 0;
}
#endif
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